Jump to content

Ventrolateral preoptic nucleus: Difference between revisions

From Wikipedia, the free encyclopedia
Browse history interactively
← Previous edit
Content deleted Content added
VisualWikitext
OAbot (talk | contribs)
Bots
439,234 edits
m Open access bot: add pmc identifier to citation with #oabot.
Citation bot (talk | contribs)
Bots
5,384,885 edits
Altered journal. Added url. | Use this bot. Report bugs. | Suggested by Headbomb | #UCB_toolbar
 
(22 intermediate revisions by 15 users not shown)
Line 1: Line 1:
{{short description|Nucleus of the anterior hypothalamus}}
{{cs1 config|name-list-style=vanc|display-authors=6}}
{{Infobox brain
{{Infobox brain
| Name = Ventrolateral Preoptic Nucleus
| Name = Ventrolateral preoptic nucleus
| Image = Hypothalamus_small.gif
| Image = Hypothalamus_small.gif
| Caption = The VLPO is located at the anterior of the Hypothalamus. It is also called the intermediate nucleus of the preoptic area
| Caption = The VLPO is located at the anterior of the hypothalamus. It is also called the intermediate nucleus of the preoptic area
| Acronym = VLPO or IPA
| Acronym = VLPO or IPA
| part_of = Preoptic nucleus
| part_of = Preoptic nucleus
}}
}}

The '''ventrolateral preoptic nucleus''' ('''VLPO'''), also known as the '''intermediate nucleus of the preoptic area''' ('''IPA'''), is a small cluster of [[neuron]]s situated in the anterior [[hypothalamus]], sitting just above and to the side of the [[optic chiasm]] in the brain of humans and other animals.<ref name=":0">{{Cite journal|last=Saper|first=Clifford B.|last2=Fuller|first2=Patrick M.|last3=Pedersen|first3=Nigel P.|last4=Lu|first4=Jun|last5=Scammell|first5=Thomas E.|date=2010|title=Sleep State Switching|journal=Neuron|language=en|volume=68|issue=6|pages=1023–1042|doi=10.1016/j.neuron.2010.11.032|pmc=3026325}}</ref><ref name=":1">{{Cite journal|last=Saper|first=Clifford B.|last2=Scammell|first2=Thomas E.|last3=Lu|first3=Jun|date=2005|title=Hypothalamic regulation of sleep and circadian rhythms|journal=Nature|language=en|volume=437|issue=7063|pages=1257–1263|doi=10.1038/nature04284|issn=0028-0836}}</ref> The brain's sleep-promoting nuclei (e.g., the VLPO, [[parafacial zone]], [[nucleus accumbens core]], and [[lateral hypothalamic]] [[melanin-concentrating hormone|MCH]] neurons),<ref name="PZ primary source">{{cite journal | vauthors = Anaclet C, Ferrari L, Arrigoni E, Bass CE, Saper CB, Lu J, Fuller PM | title = The GABAergic parafacial zone is a medullary slow wave sleep-promoting center | journal = Nat. Neurosci. | volume = 17 | issue = 9 | pages = 1217–1224 | date = September 2014 | pmid = 25129078 | pmc = 4214681 | doi = 10.1038/nn.3789 | quote = In the present study we show, for the first time, that activation of a delimited node of GABAergic neurons located in the medullary PZ can potently initiate SWS and cortical SWA in behaving animals.&nbsp;... For now however it remains unclear if the PZ is interconnected with other sleep– and wake–promoting nodes beyond the wake–promoting PB.&nbsp;... The intensity of cortical slow–wave–activity (SWA: 0.5–4Hz) during SWS is also widely accepted as a reliable indicator of sleep need&nbsp;... In conclusion, in the present study we demonstrated that all polygraphic and neurobehavioral manifestation of SWS, including SWA, can be initiated in behaving animals by the selective activation of a delimited node of GABAergic medullary neurons.| url = https://dash.harvard.edu/bitstream/handle/1/14351306/4214681.pdf?sequence=1 }}</ref><ref name="ARAS, sleep, and the parafacial zone review">{{cite journal | vauthors = Schwartz MD, Kilduff TS | title = The Neurobiology of Sleep and Wakefulness | journal = The Psychiatric Clinics of North America | volume = 38 | issue = 4 | pages = 615–644 | date = December 2015 | pmid = 26600100 | pmc = 4660253 | doi = 10.1016/j.psc.2015.07.002 | quote = More recently, the medullary parafacial zone (PZ) adjacent to the facial nerve was identified as a sleep-promoting center on the basis of anatomical, electrophysiological and chemo- and optogenetic studies.<sup>23, 24</sup> GABAergic PZ neurons inhibit glutamatergic parabrachial (PB) neurons that project to the BF,<sup>25</sup> thereby promoting NREM sleep at the expense of wakefulness and REM sleep.&nbsp;... Sleep is regulated by GABAergic populations in both the preoptic area and the brainstem; increasing evidence suggests a role for the melanin-concentrating hormone cells of the lateral hypothalamus and the parafacial zone of the brainstem}}</ref><ref name="GABAergic neurons review">{{cite journal | vauthors = Brown RE, McKenna JT | title = Turning a Negative into a Positive: Ascending GABAergic Control of Cortical Activation and Arousal | journal = Front. Neurol. | volume = 6 | issue = | pages = 135 | date = June 2015 | pmid = 26124745 | pmc = 4463930 | doi = 10.3389/fneur.2015.00135 | quote = The sleep-promoting action of GABAergic neurons located in the preoptic hypothalamus (6–8) is now well-known and accepted (9). More recently, other groups of sleep-promoting GABAergic neurons in the lateral hypothalamus (melanin-concentrating hormone neurons) and brainstem [parafacial zone; (10)] have been identified.}}</ref><ref name="Slow-wave sleep and NAcc core A2AR neurons - Sept 2017 primary source">{{cite journal | vauthors = Oishi Y, Xu Q, Wang L, Zhang BJ, Takahashi K, Takata Y, Luo YJ, Cherasse Y, Schiffmann SN, de Kerchove d'Exaerde A, Urade Y, Qu WM, Huang ZL, Lazarus M | title = Slow-wave sleep is controlled by a subset of nucleus accumbens core neurons in mice | journal = Nature Communications | volume = 8 | issue = 1 | pages = 734 | date = September 2017 | pmid = 28963505 | pmc = 5622037 | doi = 10.1038/s41467-017-00781-4 | quote = Here, we show that chemogenetic or optogenetic activation of excitatory adenosine A2A receptor-expressing indirect pathway neurons in the core region of the NAc strongly induces slow-wave sleep. Chemogenetic inhibition of the NAc indirect pathway neurons prevents the sleep induction, but does not affect the homoeostatic sleep rebound.}}</ref> together with the [[ascending reticular activating system|ascending arousal system]] which includes components in the brainstem, hypothalamus and basal forebrain, are the interconnected neural systems which control states of arousal, sleep, and transitions between these two states.<ref name=":0" /><ref name="ARAS, sleep, and the parafacial zone review" /><ref name="GABAergic neurons review" /> The VLPO is active during [[sleep]], particularly during [[non-rapid eye movement sleep]] (NREM sleep),<ref name=":2">{{Cite journal|last=Sherin|first=J. E.|last2=Shiromani|first2=P. J.|last3=McCarley|first3=R. W.|last4=Saper|first4=C. B.|date=1996-01-12|title=Activation of Ventrolateral Preoptic Neurons During Sleep|journal=Science|language=en|volume=271|issue=5246|pages=216–219|doi=10.1126/science.271.5246.216|pmid=8539624|issn=0036-8075}}</ref> and releases inhibitory [[neurotransmitter]]s, mainly [[gamma-Aminobutyric acid|GABA]] and [[galanin]], which inhibit neurons of the [[ascending reticular activating system|ascending arousal system]] that are involved in [[wakefulness]] and arousal.<ref name=":0" /><ref>{{Cite journal|last=Brown|first=Ritchie E.|last2=Basheer|first2=Radhika|last3=McKenna|first3=James T.|last4=Strecker|first4=Robert E.|last5=McCarley|first5=Robert W.|date=2012|title=Control of Sleep and Wakefulness|journal=Physiological Reviews|language=en|volume=92|issue=3|pages=1087–1187|doi=10.1152/physrev.00032.2011|pmid=22811426|pmc=3621793|issn=0031-9333}}</ref> The VLPO is in turn innervated by neurons from several components of the ascending arousal system.<ref name=":3">{{Cite journal|last=Gallopin|first=Thierry|last2=Fort|first2=Patrice|last3=Eggermann|first3=Emmanuel|last4=Cauli|first4=Bruno|last5=Luppi|first5=Pierre-Hervé|last6=Rossier|first6=Jean|last7=Audinat|first7=Etienne|last8=Mühlethaler|first8=Michel|last9=Serafin|first9=Mauro|date=2000|title=Identification of sleep-promoting neurons in vitro|journal=Nature|language=en|volume=404|issue=6781|pages=992–995|doi=10.1038/35010109|pmid=10801127|issn=0028-0836}}</ref> The VLPO is activated by the endogenous sleep-promoting substances [[adenosine]]<ref>{{Cite journal|last=Scammell|first=T.E|last2=Gerashchenko|first2=D.Y|last3=Mochizuki|first3=T|last4=McCarthy|first4=M.T|last5=Estabrooke|first5=I.V|last6=Sears|first6=C.A|last7=Saper|first7=C.B|last8=Urade|first8=Y|last9=Hayaishi|first9=O|date=2001|title=An adenosine A2a agonist increases sleep and induces Fos in ventrolateral preoptic neurons|journal=Neuroscience|volume=107|issue=4|pages=653–663|doi=10.1016/s0306-4522(01)00383-9|issn=0306-4522}}</ref><ref name = "Gallopin2005"/> and [[prostaglandin D2]].<ref name="Scammell1998">
The '''ventrolateral preoptic nucleus''' ('''VLPO'''), also known as the '''intermediate nucleus of the preoptic area''' ('''IPA'''), is a small cluster of [[neuron]]s situated in the anterior [[hypothalamus]], sitting just above and to the side of the [[optic chiasm]] in the brain of humans and other animals.<ref name="Saper_2010">{{cite journal | vauthors = Saper CB, Fuller PM, Pedersen NP, Lu J, Scammell TE | title = Sleep state switching | journal = Neuron | volume = 68 | issue = 6 | pages = 1023–1042 | date = December 2010 | pmid = 21172606 | pmc = 3026325 | doi = 10.1016/j.neuron.2010.11.032 }}</ref><ref name="Saper_2005">{{cite journal | vauthors = Saper CB, Scammell TE, Lu J | title = Hypothalamic regulation of sleep and circadian rhythms | journal = Nature | volume = 437 | issue = 7063 | pages = 1257–1263 | date = October 2005 | pmid = 16251950 | doi = 10.1038/nature04284 | s2cid = 1793658 }}</ref> The brain's sleep-promoting nuclei (e.g., the VLPO, [[parafacial zone]], [[nucleus accumbens core]], and [[lateral hypothalamic]] [[melanin-concentrating hormone|MCH]] neurons),<ref name="PZ primary source">{{cite journal | vauthors = Anaclet C, Ferrari L, Arrigoni E, Bass CE, Saper CB, Lu J, Fuller PM | title = The GABAergic parafacial zone is a medullary slow wave sleep-promoting center | journal = Nat. Neurosci. | volume = 17 | issue = 9 | pages = 1217–1224 | date = September 2014 | pmid = 25129078 | pmc = 4214681 | doi = 10.1038/nn.3789 | quote = In the present study we show, for the first time, that activation of a delimited node of GABAergic neurons located in the medullary PZ can potently initiate SWS and cortical SWA in behaving animals.&nbsp;... For now however it remains unclear if the PZ is interconnected with other sleep– and wake–promoting nodes beyond the wake–promoting PB.&nbsp;... The intensity of cortical slow–wave–activity (SWA: 0.5–4Hz) during SWS is also widely accepted as a reliable indicator of sleep need&nbsp;... In conclusion, in the present study we demonstrated that all polygraphic and neurobehavioral manifestation of SWS, including SWA, can be initiated in behaving animals by the selective activation of a delimited node of GABAergic medullary neurons.| url = https://dash.harvard.edu/bitstream/handle/1/14351306/4214681.pdf?sequence=1 }}</ref><ref name="ARAS, sleep, and the parafacial zone review">{{cite journal | vauthors = Schwartz MD, Kilduff TS | title = The Neurobiology of Sleep and Wakefulness | journal = The Psychiatric Clinics of North America | volume = 38 | issue = 4 | pages = 615–644 | date = December 2015 | pmid = 26600100 | pmc = 4660253 | doi = 10.1016/j.psc.2015.07.002 | quote = More recently, the medullary parafacial zone (PZ) adjacent to the facial nerve was identified as a sleep-promoting center on the basis of anatomical, electrophysiological and chemo- and optogenetic studies.<sup>23, 24</sup> GABAergic PZ neurons inhibit glutamatergic parabrachial (PB) neurons that project to the BF,<sup>25</sup> thereby promoting NREM sleep at the expense of wakefulness and REM sleep.&nbsp;... Sleep is regulated by GABAergic populations in both the preoptic area and the brainstem; increasing evidence suggests a role for the melanin-concentrating hormone cells of the lateral hypothalamus and the parafacial zone of the brainstem}}</ref><ref name="GABAergic neurons review">{{cite journal | vauthors = Brown RE, McKenna JT | title = Turning a Negative into a Positive: Ascending GABAergic Control of Cortical Activation and Arousal | journal = Front. Neurol. | volume = 6 | pages = 135 | date = June 2015 | pmid = 26124745 | pmc = 4463930 | doi = 10.3389/fneur.2015.00135 | quote = The sleep-promoting action of GABAergic neurons located in the preoptic hypothalamus (6–8) is now well-known and accepted (9). More recently, other groups of sleep-promoting GABAergic neurons in the lateral hypothalamus (melanin-concentrating hormone neurons) and brainstem [parafacial zone; (10)] have been identified.| doi-access = free }}</ref><ref name="Slow-wave sleep and NAcc core A2AR neurons - Sept 2017 primary source">{{cite journal | vauthors = Oishi Y, Xu Q, Wang L, Zhang BJ, Takahashi K, Takata Y, Luo YJ, Cherasse Y, Schiffmann SN, de Kerchove d'Exaerde A, Urade Y, Qu WM, Huang ZL, Lazarus M | title = Slow-wave sleep is controlled by a subset of nucleus accumbens core neurons in mice | journal = Nature Communications | volume = 8 | issue = 1 | pages = 734 | date = September 2017 | pmid = 28963505 | pmc = 5622037 | doi = 10.1038/s41467-017-00781-4 | quote = Here, we show that chemogenetic or optogenetic activation of excitatory adenosine A2A receptor-expressing indirect pathway neurons in the core region of the NAc strongly induces slow-wave sleep. Chemogenetic inhibition of the NAc indirect pathway neurons prevents the sleep induction, but does not affect the homoeostatic sleep rebound.}}</ref> together with the [[ascending reticular activating system|ascending arousal system]] which includes components in the brainstem, hypothalamus and basal forebrain, are the interconnected neural systems which control states of arousal, sleep, and transitions between these two states.<ref name="Saper_2010" /><ref name="ARAS, sleep, and the parafacial zone review" /><ref name="GABAergic neurons review" /> The VLPO is active during [[sleep]], particularly during [[non-rapid eye movement sleep]] (NREM sleep),<ref name="Sherin_1996">{{cite journal | vauthors = Sherin JE, Shiromani PJ, McCarley RW, Saper CB | title = Activation of ventrolateral preoptic neurons during sleep | journal = Science | volume = 271 | issue = 5246 | pages = 216–219 | date = January 1996 | pmid = 8539624 | doi = 10.1126/science.271.5246.216 | s2cid = 19804653 }}</ref> and releases inhibitory [[neurotransmitter]]s, mainly [[gamma-Aminobutyric acid|GABA]] and [[galanin]], which inhibit neurons of the [[ascending reticular activating system|ascending arousal system]] that are involved in [[wakefulness]] and arousal.<ref name="Saper_2010" /><ref>{{cite journal | vauthors = Brown RE, Basheer R, McKenna JT, Strecker RE, McCarley RW | title = Control of sleep and wakefulness | journal = Physiological Reviews | volume = 92 | issue = 3 | pages = 1087–1187 | date = July 2012 | pmid = 22811426 | pmc = 3621793 | doi = 10.1152/physrev.00032.2011 }}</ref> The VLPO is in turn innervated by neurons from several components of the ascending arousal system.<ref name="Gallopin_2000">{{cite journal | vauthors = Gallopin T, Fort P, Eggermann E, Cauli B, Luppi PH, Rossier J, Audinat E, Mühlethaler M, Serafin M | title = Identification of sleep-promoting neurons in vitro | journal = Nature | volume = 404 | issue = 6781 | pages = 992–995 | date = April 2000 | pmid = 10801127 | doi = 10.1038/35010109 | s2cid = 4364527 }}</ref><ref>{{cite journal | vauthors = Walter A, van der Spek L, Hardy E, Bemelmans AP, Rouach N, Rancillac A | title = Structural and functional connections between the median and the ventrolateral preoptic nucleus | journal = Brain Structure & Function | volume = 224 | issue = 9 | pages = 3045–3057 | date = December 2019 | pmid = 31493023 | doi = 10.1007/s00429-019-01935-4 }}</ref> The VLPO is activated by the endogenous sleep-promoting substances [[adenosine]]<ref>{{cite journal | vauthors = Scammell TE, Gerashchenko DY, Mochizuki T, McCarthy MT, Estabrooke IV, Sears CA, Saper CB, Urade Y, Hayaishi O | title = An adenosine A2a agonist increases sleep and induces Fos in ventrolateral preoptic neurons | journal = Neuroscience | volume = 107 | issue = 4 | pages = 653–663 | date = 2001 | pmid = 11720788 | doi = 10.1016/s0306-4522(01)00383-9 | s2cid = 45189308 }}</ref><ref name = "Gallopin2005"/> and [[prostaglandin D2]].<ref name="Scammell1998">
{{Cite journal | author=Scammell T| title=Activation of ventrolateral preoptic neurons by the somnogen prostaglandin D2 | journal=[[PNAS]] | volume=95 | issue=13 | year=1998 | pages= 7754–7759| doi=10.1073/pnas.95.13.7754| pmid=9636223 | pmc=22747}}
{{cite journal | vauthors = Scammell T, Gerashchenko D, Urade Y, Onoe H, Saper C, Hayaishi O | title = Activation of ventrolateral preoptic neurons by the somnogen prostaglandin D2 | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 95 | issue = 13 | pages = 7754–7759 | date = June 1998 | pmid = 9636223 | pmc = 22747 | doi = 10.1073/pnas.95.13.7754 | doi-access = free }}
</ref> The VLPO is inhibited during wakefulness by the arousal-inducing neurotransmitters [[norepinephrine]] and [[acetylcholine]].<ref name=":3" /> The role of the VLPO in sleep and wakefulness, and its association with [[sleep disorder]]s – particularly [[insomnia]] and [[narcolepsy]] – is a growing area of neuroscience research.
</ref><ref>{{cite journal | vauthors = Scharbarg E, Walter A, Lecoin L, Gallopin T, Lemaître F, Guille-Collignon M, Rouach N, Rancillac A | title = Prostaglandin D<sub>2</sub> Controls Local Blood Flow and Sleep-Promoting Neurons in the VLPO via Astrocyte-Derived Adenosine | journal = ACS Chemical Neuroscience | volume = 14 | issue = 6 | pages = 1063–1070 | date = March 2023 | pmid = 36847485 | doi = 10.1021/acschemneuro.2c00660 | url = https://hal.science/hal-04007074/file/31-Scharbarg%20et%20al%202023%20VA.pdf }}</ref> The VLPO is inhibited during wakefulness by the arousal-inducing neurotransmitters [[norepinephrine]] and [[acetylcholine]].<ref name="Gallopin_2000" /><ref>{{cite journal | vauthors = Sangare A, Dubourget R, Geoffroy H, Gallopin T, Rancillac A | title = Serotonin differentially modulates excitatory and inhibitory synaptic inputs to putative sleep-promoting neurons of the ventrolateral preoptic nucleus | journal = Neuropharmacology | volume = 109 | pages = 29–40 | date = October 2016 | pmid = 27238836 | doi = 10.1016/j.neuropharm.2016.05.015 | url = https://www.hal.inserm.fr/inserm-02121065v2/file/Serotonin%20differentially%20modulates%20excitatory.pdf }}</ref> The role of the VLPO in sleep and wakefulness, and its association with [[sleep disorder]]s – particularly [[insomnia]] and [[narcolepsy]] – is a growing area of neuroscience research.


==Structure==
==Structure==


At least 80% of neurons in the VLPO that project to the ascending arousal system are GABAergic (neurons that produce GABA).<ref name="Sherin 1998">
At least 80% of neurons in the VLPO that project to the ascending arousal system are GABAergic (neurons that produce GABA).<ref name="Sherin 1998">
{{Cite journal | author=Sherin J | title=Innervation of Histaminergic Tuberomammillary Neurons by GABAergic and Galaninergic Neurons in the Ventrolateral Preoptic Nucleus of the Rat | journal=[[The Journal of Neuroscience]] | volume=18 | issue = 12 | year=1998 | pages=4705–4721 | doi=10.1523/JNEUROSCI.18-12-04705.1998 }}
{{Cite journal | author=Sherin J | title=Innervation of Histaminergic Tuberomammillary Neurons by GABAergic and Galaninergic Neurons in the Ventrolateral Preoptic Nucleus of the Rat | journal=[[The Journal of Neuroscience]] | volume=18 | issue = 12 | year=1998 | pages=4705–4721 | doi=10.1523/JNEUROSCI.18-12-04705.1998 | pmid=9614245 | pmc=6792696 | doi-access=free }}
</ref>
</ref>
''In vitro'' studies in rats have shown that many neurons in the VLPO that are inhibited by norepinephrine or acetylcholine are multipolar triangular shaped cells with low threshold spikes.<ref name=":3" /> These triangular multipolar neurons exist in two sub-populations in the VLPO:
''In vitro'' studies in rats have shown that many neurons in the VLPO that are inhibited by norepinephrine or acetylcholine are multipolar triangular shaped cells with low threshold spikes.<ref name="Gallopin_2000" /> These triangular multipolar neurons exist in two sub-populations in the VLPO:
*Type 1 – inhibited by serotonin.
*Type 1 – inhibited by serotonin.
*Type 2 – excited by serotonin and adenosine.
*Type 2 – excited by serotonin and adenosine.


⚫
As adenosine accumulates during wakefulness<ref name="Gallopin2005">{{cite journal | vauthors = Gallopin T, Luppi PH, Cauli B, Urade Y, Rossier J, Hayaishi O, Lambolez B, Fort P | title = The endogenous somnogen adenosine excites a subset of sleep-promoting neurons via A2A receptors in the ventrolateral preoptic nucleus | journal = Neuroscience | volume = 134 | issue = 4 | pages = 1377–1390 | year = 2005 | pmid = 16039802 | doi = 10.1016/j.neuroscience.2005.05.045 | s2cid = 27732204 }}
As adenosine accumulates during wakefulness<ref name="Gallopin2005">
</ref><ref>{{cite journal | vauthors = Scharbarg E, Daenens M, Lemaître F, Geoffroy H, Guille-Collignon M, Gallopin T, Rancillac A | title = Astrocyte-derived adenosine is central to the hypnogenic effect of glucose | journal = Scientific Reports | volume = 6 | issue = 1 | pages = 19107 | date = January 2016 | pmid = 26755200 | pmc = 4709579 | doi = 10.1038/srep19107 }}</ref> it is likely that type 2 cells play a role in sleep induction.
{{Cite journal | author=Gallopin T | title=The endogenous somnogen adenosine excites a subset of sleep-promoting neurons via A2A receptors in the ventrolateral preoptic nucleus |journal=[[Neuroscience (journal)|Neuroscience]] | volume=134 | year=2005 | pages=1377–1390 | doi= 10.1016/j.neuroscience.2005.05.045 | pmid=16039802 | issue=4}}
</ref> it is likely that type 2 cells play a role in sleep induction.


The remaining third of neurons in the VLPO are excited by norepinephrine. Their role is unclear.
The remaining third of neurons in the VLPO are excited by norepinephrine. Their role is unclear.

In mice, all galaninergic neurons of the VLPO are inhibited by norepinephrine and excited by adenosine, although serotonin still differentiates Type 1 and Type 2 neurons.<ref>{{cite journal | vauthors = Sangare A, Dubourget R, Geoffroy H, Gallopin T, Rancillac A | title = Serotonin differentially modulates excitatory and inhibitory synaptic inputs to putative sleep-promoting neurons of the ventrolateral preoptic nucleus | journal = Neuropharmacology | volume = 109 | pages = 29–40 | date = October 2016 | pmid = 27238836 | doi = 10.1016/j.neuropharm.2016.05.015 | url = https://www.hal.inserm.fr/inserm-02121065v2/file/Serotonin%20differentially%20modulates%20excitatory.pdf }}</ref><ref>{{cite journal | vauthors = Rancillac A | title = Serotonin and sleep-promoting neurons | journal = Oncotarget | volume = 7 | issue = 48 | pages = 78222–78223 | date = November 2016 | pmid = 27861160 | pmc = 5346632 | doi = 10.18632/oncotarget.13419 }}</ref>


==Function==
==Function==
Line 29: Line 33:
===Sleep/wakefulness===
===Sleep/wakefulness===
[[File:VLPO Flip-Flop Switch Hypothesis.png|thumb|400px|Schematic representation of the Flip-Flop Switch Hypothesis]]
[[File:VLPO Flip-Flop Switch Hypothesis.png|thumb|400px|Schematic representation of the Flip-Flop Switch Hypothesis]]
In the early 20th century, von Economo noted that humans who had encephalitis with lesions in the anterior hypothalamus had insomnia, and proposed a sleep-promoting influence from that area.<ref name=":1" /> Animal studies in the mid-20th century in rats and cats confirmed that very large lesions in the preoptic area and basal forebrain resulted in insomnia<ref name="Nauta1946">
In the early 20th century, [[Constantin von Economo]] noted that humans who had encephalitis with lesions in the anterior hypothalamus had insomnia, and proposed a sleep-promoting influence from that area.<ref name="Saper_2005" /> Animal studies in the mid-20th century in rats and cats confirmed that very large lesions in the preoptic area and basal forebrain resulted in insomnia<ref name="Nauta1946">
{{Cite journal | author=Nauta W | title=Hypothalamic regulation of sleep in rats | journal=[[Journal of Neurophysiology]] | volume=9 | year=1946 | pages=285–314| doi=10.1152/jn.1946.9.4.285 | pmid=20991815 }}
{{Cite journal | author=Nauta W | title=Hypothalamic regulation of sleep in rats | journal=[[Journal of Neurophysiology]] | volume=9 | year=1946 | pages=285–314| doi=10.1152/jn.1946.9.4.285 | pmid=20991815 }}
</ref><ref name="McGinty1968">
</ref><ref name="McGinty1968">
{{Cite journal | author=McGinty D | title=Sleep Suppression after Basal Forebrain Lesions in the Cat | journal=[[Science (journal)|Science]] | volume=160 | year=1968 | pages=1253–1255 | doi=10.1126/science.160.3833.1253 | pmid=5689683 | issue=3833}}
{{Cite journal | author=McGinty D | title=Sleep Suppression after Basal Forebrain Lesions in the Cat | journal=[[Science (journal)|Science]] | volume=160 | year=1968 | pages=1253–1255 | doi=10.1126/science.160.3833.1253 | pmid=5689683 | issue=3833| s2cid=24677928 }}
</ref> but did not identify the cell group that was responsible. In 1996, Sherin and colleagues reported the presence of a cell group in the VLPO that expresses cFos (a protein often found in neurons that have recently been active) during sleep, and that these neurons contain the inhibitory neurotransmitters GABA and galanin.<ref name="Sherin 1998" /><ref name=":2" /> . These same neurons were found to innervate components of the ascending arousal system, including the [[tuberomammillary nucleus]] (TMN) and other components of the lateral hypothalamus; the [[Raphe nuclei|raphe nuclei;]] the [[locus coeruleus]] (LC); the [[Pedunculopontine nucleus|pedunculopontine]] (PPT) and [[laterodorsal tegmental nucleus|laterodorsal tegmental nuclei]] (LDT); and the parabrachial nucleus (PB). More recent studies using opto- or chemogenetic activation of VLPO neurons have confirmed that they promote sleep.<ref>{{Cite journal|last=Kroeger|first=Daniel|last2=Absi|first2=Gianna|last3=Gagliardi|first3=Celia|last4=Bandaru|first4=Sathyajit S.|last5=Madara|first5=Joseph C.|last6=Ferrari|first6=Loris L.|last7=Arrigoni|first7=Elda|last8=Münzberg|first8=Heike|last9=Scammell|first9=Thomas E.|date=2018|title=Galanin neurons in the ventrolateral preoptic area promote sleep and heat loss in mice|journal=Nature Communications|language=en|volume=9|issue=1|pages=|doi=10.1038/s41467-018-06590-7|issn=2041-1723|pmc=6175893}}</ref>
</ref> but did not identify the cell group that was responsible. In 1996, Sherin and colleagues reported the presence of a cell group in the VLPO that expresses cFos (a protein often found in neurons that have recently been active) during sleep, and that these neurons contain the inhibitory neurotransmitters GABA and galanin.<ref name="Sherin 1998" /><ref name="Sherin_1996" /> These same neurons receive inputs from the median preoptic nucleus (MnPO) <ref>{{cite journal | vauthors = Walter A, van der Spek L, Hardy E, Bemelmans AP, Rouach N, Rancillac A | title = Structural and functional connections between the median and the ventrolateral preoptic nucleus | journal = Brain Structure & Function | volume = 224 | issue = 9 | pages = 3045–3057 | date = December 2019 | pmid = 31493023 | doi = 10.1007/s00429-019-01935-4 }}</ref> and were found to innervate components of the ascending arousal system, including the [[tuberomammillary nucleus]] (TMN) and other components of the lateral hypothalamus; the [[raphe nuclei]]; the [[locus coeruleus]] (LC); the [[Pedunculopontine nucleus|pedunculopontine]] (PPT) and [[laterodorsal tegmental nucleus|laterodorsal tegmental nuclei]] (LDT); and the parabrachial nucleus (PB). More recent studies using opto- or chemogenetic activation of VLPO neurons have confirmed that they promote sleep.<ref>{{cite journal | vauthors = Kroeger D, Absi G, Gagliardi C, Bandaru SS, Madara JC, Ferrari LL, Arrigoni E, Münzberg H, Scammell TE, Saper CB, Vetrivelan R | title = Galanin neurons in the ventrolateral preoptic area promote sleep and heat loss in mice | journal = Nature Communications | volume = 9 | issue = 1 | pages = 4129 | date = October 2018 | pmid = 30297727 | pmc = 6175893 | doi = 10.1038/s41467-018-06590-7 }}</ref>


The sleep-promoting effects of the VLPO neurons is thought to be due to release of GABA and possibly galanin that suppresses firing of arousal system neurons. As the VLPO is also inhibited by neurotransmitters released by components of the arousal systems, such as acetylcholine and norepinephrine,<ref name=":3" /> a current theory has proposed that the VLPO and the arousal system form a "flip-flop" circuit.<ref name=":0" /><ref name=":1" /> This term from electrical engineering denotes a circuit in which mutual inhibition means that each component of the circuit, as it turns on, turns the other off, resulting in rapid transitions from one state (wake or sleep) to the other, with minimal time in transition states. This theory has been used to create mathematical models that explain much of the wake-sleep behavior in animals, including in pathological states and responses to drugs.<ref name=":0" /><ref>{{Cite journal|last=Phillips|first=A.J.K.|last2=Robinson|first2=P.A.|date=2007|title=A Quantitative Model of Sleep-Wake Dynamics Based on the Physiology of the Brainstem Ascending Arousal System|journal=Journal of Biological Rhythms|language=en|volume=22|issue=2|pages=167–179|doi=10.1177/0748730406297512|pmid=17440218|issn=0748-7304}}</ref><ref>{{Cite journal|last=Fulcher|first=Ben D.|last2=Phillips|first2=Andrew J. K.|last3=Postnova|first3=Svetlana|last4=Robinson|first4=Peter A.|date=2014|editor-last=Mistlberger|editor-first=Ralph E.|title=A Physiologically Based Model of Orexinergic Stabilization of Sleep and Wake|journal=PLoS ONE|language=en|volume=9|issue=3|pages=e91982|doi=10.1371/journal.pone.0091982|pmid=24651580|issn=1932-6203}}</ref> [[Orexin]] neurons in the posterior lateral hypothalamus potentiate neurons in the ascending arousal system and help stabilize the brain in the waking state (and consolidated wakefulness, which builds up homeostatic sleep drive, helps stabilize the brain during later sleep). The loss of orexin neurons in the disorder narcolepsy destabilizes the wake-sleep switch, resulting in overwhelming sleep episodes during the waking day, as well as more frequent awakenings from sleep at night.<ref name=":0" />
The sleep-promoting effects of the VLPO neurons is thought to be due to release of GABA and possibly galanin that suppresses firing of arousal system neurons. As the VLPO is also inhibited by neurotransmitters released by components of the arousal systems, such as acetylcholine and norepinephrine,<ref name="Gallopin_2000" /> a current theory has proposed that the VLPO and the arousal system form a "flip-flop" circuit.<ref name="Saper_2010" /><ref name="Saper_2005" /> This term from electrical engineering denotes a circuit in which mutual inhibition means that each component of the circuit, as it turns on, turns the other off, resulting in rapid transitions from one state (wake or sleep) to the other, with minimal time in transition states. This theory has been used to create mathematical models that explain much of the wake-sleep behavior in animals, including in pathological states and responses to drugs.<ref name="Saper_2010" /><ref>{{cite journal | vauthors = Phillips AJ, Robinson PA | title = A quantitative model of sleep-wake dynamics based on the physiology of the brainstem ascending arousal system | journal = Journal of Biological Rhythms | volume = 22 | issue = 2 | pages = 167–179 | date = April 2007 | pmid = 17440218 | doi = 10.1177/0748730406297512 | s2cid = 31817324 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Fulcher BD, Phillips AJ, Postnova S, Robinson PA | title = A physiologically based model of orexinergic stabilization of sleep and wake | journal = PLOS ONE | volume = 9 | issue = 3 | pages = e91982 | date = 2014 | pmid = 24651580 | pmc = 3961294 | doi = 10.1371/journal.pone.0091982 | doi-access = free | veditors = Mistlberger RE }}</ref> [[Orexin]] neurons in the posterior lateral hypothalamus potentiate neurons in the ascending arousal system and help stabilize the brain in the waking state (and consolidated wakefulness, which builds up homeostatic sleep drive, helps stabilize the brain during later sleep). The loss of orexin neurons in the disorder narcolepsy destabilizes the wake-sleep switch, resulting in overwhelming sleep episodes during the waking day, as well as more frequent awakenings from sleep at night.<ref name="Saper_2010" />


===Circadian rhythm===
===Circadian rhythm===
There is a strong [[circadian rhythm|circadian rhythm of sleep in]] mammals. The “master clock” for circadian rhythms in mammals is the [[suprachiasmatic nucleus]] (SCN). The SCN has little if any projection directly to the VLPO neurons. Instead, they project strongly to the adjacent subparaventricular zone, which in turn contains inhibitory GABAergic neurons that innervate the dorsomedial nucleus of the hypothalamus.<ref name=":4">{{Cite journal|last=Chou|first=Thomas C.|last2=Scammell|first2=Thomas E.|last3=Gooley|first3=Joshua J.|last4=Gaus|first4=Stephanie E.|last5=Saper|first5=Clifford B.|last6=Lu|first6=Jun|date=2003|title=Critical Role of Dorsomedial Hypothalamic Nucleus in a Wide Range of Behavioral Circadian Rhythms|journal=The Journal of Neuroscience|volume=23|issue=33|pages=10691–10702|doi=10.1523/jneurosci.23-33-10691.2003|issn=0270-6474}}</ref><ref>{{Cite journal|last=Vujovic|first=Nina|last2=Gooley|first2=Joshua J.|last3=Jhou|first3=Thomas C.|last4=Saper|first4=Clifford B.|date=2015|title=Projections from the subparaventricular zone define four channels of output from the circadian timing system: Projections from the SPZ|journal=Journal of Comparative Neurology|language=en|volume=523|issue=18|pages=2714–2737|doi=10.1002/cne.23812|pmid=26010698|pmc=4607558}}</ref> Lesions of the dorsomedial nucleus almost completely eliminate the circadian rhythm of sleep. GABAergic neurons in the dorsomedial nucleus innervate the VLPO, and glutamatergic neurons innervate the lateral hypothalamus, suggesting that the dorsomedial nucleus mainly promotes wakefulness during the active period (daytime for humans).<ref name=":4" />
There is a strong [[circadian rhythm|circadian rhythm of sleep in]] mammals. The “master clock” for circadian rhythms in mammals is the [[suprachiasmatic nucleus]] (SCN). The SCN has little if any projection directly to the VLPO neurons. Instead, they project strongly to the adjacent subparaventricular zone, which in turn contains inhibitory GABAergic neurons that innervate the dorsomedial nucleus of the hypothalamus.<ref name="Chou_2003">{{cite journal | vauthors = Chou TC, Scammell TE, Gooley JJ, Gaus SE, Saper CB, Lu J | title = Critical role of dorsomedial hypothalamic nucleus in a wide range of behavioral circadian rhythms | journal = The Journal of Neuroscience | volume = 23 | issue = 33 | pages = 10691–10702 | date = November 2003 | pmid = 14627654 | pmc = 6740926 | doi = 10.1523/jneurosci.23-33-10691.2003 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Vujovic N, Gooley JJ, Jhou TC, Saper CB | title = Projections from the subparaventricular zone define four channels of output from the circadian timing system | journal = The Journal of Comparative Neurology | volume = 523 | issue = 18 | pages = 2714–2737 | date = December 2015 | pmid = 26010698 | pmc = 4607558 | doi = 10.1002/cne.23812 }}</ref> Lesions of the dorsomedial nucleus almost completely eliminate the circadian rhythm of sleep. GABAergic neurons in the dorsomedial nucleus innervate the VLPO, and glutamatergic neurons innervate the lateral hypothalamus, suggesting that the dorsomedial nucleus mainly promotes wakefulness during the active period (daytime for humans).<ref name="Chou_2003" />


==Clinical significance==
==Clinical significance==
Line 47: Line 51:
</ref>
</ref>


Lesions in the VLPO in rats results in 50-60% decrease in NREM sleep time and prolonged [[insomnia]].<ref>{{Cite journal|last=Lu|first=Jun|last2=Greco|first2=Mary Ann|last3=Shiromani|first3=Priyattam|last4=Saper|first4=Clifford B.|date=2000|title=Effect of Lesions of the Ventrolateral Preoptic Nucleus on NREM and REM Sleep|journal=The Journal of Neuroscience|volume=20|issue=10|pages=3830–3842|doi=10.1523/jneurosci.20-10-03830.2000|issn=0270-6474}}</ref> More recent research suggests that stress-induced insomnia could be due to an imbalance of input to arousal system and VLPO neurons.<ref>{{Cite journal|last=Cano|first=G.|last2=Mochizuki|first2=T.|last3=Saper|first3=C. B.|date=2008|title=Neural Circuitry of Stress-Induced Insomnia in Rats|journal=Journal of Neuroscience|language=en|volume=28|issue=40|pages=10167–10184|doi=10.1523/JNEUROSCI.1809-08.2008|issn=0270-6474}}</ref>
Lesions in the VLPO in rats results in 50-60% decrease in NREM sleep time and prolonged [[insomnia]].<ref>{{cite journal | vauthors = Lu J, Greco MA, Shiromani P, Saper CB | title = Effect of lesions of the ventrolateral preoptic nucleus on NREM and REM sleep | journal = The Journal of Neuroscience | volume = 20 | issue = 10 | pages = 3830–3842 | date = May 2000 | pmid = 10804223 | pmc = 6772663 | doi = 10.1523/jneurosci.20-10-03830.2000 | doi-access = free }}</ref> More recent research suggests that stress-induced insomnia could be due to an imbalance of input to arousal system and VLPO neurons.<ref>{{cite journal | vauthors = Cano G, Mochizuki T, Saper CB | title = Neural circuitry of stress-induced insomnia in rats | journal = The Journal of Neuroscience | volume = 28 | issue = 40 | pages = 10167–10184 | date = October 2008 | pmid = 18829974 | pmc = 2693213 | doi = 10.1523/JNEUROSCI.1809-08.2008 | doi-access = free }}</ref>


===Sedative/hypnotic drugs===
===Sedative/hypnotic drugs===
Many sedative/hypnotic drugs act by binding to and potentiating GABA-A receptors. These include older drugs such as ethanol, chloral hydrate and barbiturates, as well as newer benzodiazepines and "non-benzodiazepine" drugs (such as zolpidem, which bind to the same receptor but have a different chemical configuration), and even anesthetics such as propofol and isoflurane. As the VLPO inputs to the arousal system use this same receptor, these drugs at low doses essentially act by potentiating the VLPO, producing a sleepy state. Animal studies show that VLPO neurons show cFos activation after sedative doses of these drugs,<ref>{{Cite journal|last=Lu|first=Jun|last2=Nelson|first2=Laura E.|last3=Franks|first3=Nick|last4=Maze|first4=Mervyn|last5=Chamberlin|first5=Nancy L.|last6=Saper|first6=Clifford B.|date=2008|title=Role of endogenous sleep-wake and analgesic systems in anesthesia|journal=The Journal of Comparative Neurology|language=en|volume=508|issue=4|pages=648–662|doi=10.1002/cne.21685|pmid=18383504|pmc=4924624}}</ref> and that VLPO lesions produce resistance to their sedative effects. <ref>{{Cite journal|last=Moore|first=Jason T.|last2=Chen|first2=Jingqiu|last3=Han|first3=Bo|last4=Meng|first4=Qing Cheng|last5=Veasey|first5=Sigrid C.|last6=Beck|first6=Sheryl G.|last7=Kelz|first7=Max B.|date=2012|title=Direct Activation of Sleep-Promoting VLPO Neurons by Volatile Anesthetics Contributes to Anesthetic Hypnosis|journal=Current Biology|language=en|volume=22|issue=21|pages=2008–2016|doi=10.1016/j.cub.2012.08.042}}</ref> However, at high doses that produce a surgical plane of anesthesia, these drugs have much more widespread inhibitory effects, that do not depend upon the VLPO.<ref>{{Cite journal|last=Eikermann|first=Matthias|last2=Vetrivelan|first2=Ramalingam|last3=Grosse-Sundrup|first3=Martina|last4=Henry|first4=Mark E.|last5=Hoffmann|first5=Ulrike|last6=Yokota|first6=Shigefumi|last7=Saper|first7=Clifford B.|last8=Chamberlin|first8=Nancy L.|date=2011|title=The ventrolateral preoptic nucleus is not required for isoflurane general anesthesia|journal=Brain Research|language=en|volume=1426|pages=30–37|doi=10.1016/j.brainres.2011.10.018|pmid=22041226|pmc=3215917}}</ref>
Many [[sedative]]/hypnotic drugs act by binding to and potentiating GABA-A receptors. These include older drugs such as ethanol, chloral hydrate and barbiturates, as well as newer benzodiazepines and "non-benzodiazepine" drugs (such as zolpidem, which bind to the same receptor but have a different chemical configuration), and even anesthetics such as propofol and isoflurane. As the VLPO inputs to the arousal system use this same receptor, these drugs at low doses essentially act by potentiating the VLPO, producing a sleepy state. Animal studies show that VLPO neurons show cFos activation after sedative doses of these drugs,<ref>{{cite journal | vauthors = Lu J, Nelson LE, Franks N, Maze M, Chamberlin NL, Saper CB | title = Role of endogenous sleep-wake and analgesic systems in anesthesia | journal = The Journal of Comparative Neurology | volume = 508 | issue = 4 | pages = 648–662 | date = June 2008 | pmid = 18383504 | pmc = 4924624 | doi = 10.1002/cne.21685 }}</ref> and that VLPO lesions produce resistance to their sedative effects.<ref>{{cite journal | vauthors = Moore JT, Chen J, Han B, Meng QC, Veasey SC, Beck SG, Kelz MB | title = Direct activation of sleep-promoting VLPO neurons by volatile anesthetics contributes to anesthetic hypnosis | journal = Current Biology | volume = 22 | issue = 21 | pages = 2008–2016 | date = November 2012 | pmid = 23103189 | pmc = 3628836 | doi = 10.1016/j.cub.2012.08.042 }}</ref> However, at high doses that produce a surgical plane of anesthesia, these drugs have much more widespread inhibitory effects, that do not depend upon the VLPO.<ref>{{cite journal | vauthors = Eikermann M, Vetrivelan R, Grosse-Sundrup M, Henry ME, Hoffmann U, Yokota S, Saper CB, Chamberlin NL | title = The ventrolateral preoptic nucleus is not required for isoflurane general anesthesia | journal = Brain Research | volume = 1426 | pages = 30–37 | date = December 2011 | pmid = 22041226 | pmc = 3215917 | doi = 10.1016/j.brainres.2011.10.018 }}</ref> Studies have shown that multiple sedative/hypnotic drugs that act by potentiating GABA-A receptors, including ethanol, chloral hydrate, propofol and gas anesthetics such as [[isoflurane]], at sedative doses increase the activity of the VLPO neurons in mice.<ref name="Moore2012">
<br />{{Reflist}}Studies have shown that multiple sedative/hypnotic drugs that act by potentiating GABA-A receptors, including ethanol, chloral hydrate, propofol and gas anesthetics such as [[isoflurane]], at sedative doses increase the activity of the VLPO neurons in mice.<ref name="Moore2012">
{{Cite journal | author=Moore J | title=Direct Activation of Sleep-Promoting VLPO Neurons by Volatile Anesthetics Contributes to Anesthetic Hypnosis | journal=[[Current Biology]] | volume=22 | issue=21 | year=2012 | pages=2008–2016| doi=10.1016/j.cub.2012.08.042| pmid=23103189 | pmc=3628836 }}
{{Cite journal | author=Moore J | title=Direct Activation of Sleep-Promoting VLPO Neurons by Volatile Anesthetics Contributes to Anesthetic Hypnosis | journal=[[Current Biology]] | volume=22 | issue=21 | year=2012 | pages=2008–2016| doi=10.1016/j.cub.2012.08.042| pmid=23103189 | pmc=3628836 }}
</ref> This finding suggests that at relatively low sedative doses, these medications may have a common mechanism of action, which includes potentiating the firing of VLPO neurons. High doses used in surgical anesthesia, however, reduce activity of neurons throughout the nervous system.
</ref> This finding suggests that at relatively low sedative doses, these medications may have a common mechanism of action, which includes potentiating the firing of VLPO neurons. High doses used in surgical anesthesia, however, reduce activity of neurons throughout the nervous system.


==References==
==References==
{{Reflist}}


==External links==
==External links==
* {{BrainInfo|ancil|-1174961713}}
* {{BrainInfo|ancil|-1174961713}}

⚫
{{cite journal |vauthors=Gallopin T, Luppi PH, Cauli B, Urade Y, Rossier J, Hayaishi O, Lambolez B, Fort P | title=The endogenous somnogen adenosine excites a subset of sleep-promoting neurons via A2A receptors in the ventrolateral preoptic nucleus | journal=Neuroscience | volume= 134| pages=1377–90| year=2005 | pmid=16039802 | doi=10.1016/j.neuroscience.2005.05.045 | issue=4}}


{{Diencephalon}}
{{Diencephalon}}

Latest revision as of 03:17, 29 September 2024

Ventrolateral preoptic nucleus
The VLPO is located at the anterior of the hypothalamus. It is also called the intermediate nucleus of the preoptic area
Details
Part ofPreoptic nucleus
Identifiers
Acronym(s)VLPO or IPA
NeuroNames3122
Anatomical terms of neuroanatomy

The ventrolateral preoptic nucleus (VLPO), also known as the intermediate nucleus of the preoptic area (IPA), is a small cluster of neurons situated in the anterior hypothalamus, sitting just above and to the side of the optic chiasm in the brain of humans and other animals.[1][2] The brain's sleep-promoting nuclei (e.g., the VLPO, parafacial zone, nucleus accumbens core, and lateral hypothalamic MCH neurons),[3][4][5][6] together with the ascending arousal system which includes components in the brainstem, hypothalamus and basal forebrain, are the interconnected neural systems which control states of arousal, sleep, and transitions between these two states.[1][4][5] The VLPO is active during sleep, particularly during non-rapid eye movement sleep (NREM sleep),[7] and releases inhibitory neurotransmitters, mainly GABA and galanin, which inhibit neurons of the ascending arousal system that are involved in wakefulness and arousal.[1][8] The VLPO is in turn innervated by neurons from several components of the ascending arousal system.[9][10] The VLPO is activated by the endogenous sleep-promoting substances adenosine[11][12] and prostaglandin D2.[13][14] The VLPO is inhibited during wakefulness by the arousal-inducing neurotransmitters norepinephrine and acetylcholine.[9][15] The role of the VLPO in sleep and wakefulness, and its association with sleep disorders – particularly insomnia and narcolepsy – is a growing area of neuroscience research.

Structure

[edit]

At least 80% of neurons in the VLPO that project to the ascending arousal system are GABAergic (neurons that produce GABA).[16] In vitro studies in rats have shown that many neurons in the VLPO that are inhibited by norepinephrine or acetylcholine are multipolar triangular shaped cells with low threshold spikes.[9] These triangular multipolar neurons exist in two sub-populations in the VLPO:

  • Type 1 – inhibited by serotonin.
  • Type 2 – excited by serotonin and adenosine.

As adenosine accumulates during wakefulness[12][17] it is likely that type 2 cells play a role in sleep induction.

The remaining third of neurons in the VLPO are excited by norepinephrine. Their role is unclear.

In mice, all galaninergic neurons of the VLPO are inhibited by norepinephrine and excited by adenosine, although serotonin still differentiates Type 1 and Type 2 neurons.[18][19]

Function

[edit]

Sleep/wakefulness

[edit]
Schematic representation of the Flip-Flop Switch Hypothesis

In the early 20th century, Constantin von Economo noted that humans who had encephalitis with lesions in the anterior hypothalamus had insomnia, and proposed a sleep-promoting influence from that area.[2] Animal studies in the mid-20th century in rats and cats confirmed that very large lesions in the preoptic area and basal forebrain resulted in insomnia[20][21] but did not identify the cell group that was responsible. In 1996, Sherin and colleagues reported the presence of a cell group in the VLPO that expresses cFos (a protein often found in neurons that have recently been active) during sleep, and that these neurons contain the inhibitory neurotransmitters GABA and galanin.[16][7] These same neurons receive inputs from the median preoptic nucleus (MnPO) [22] and were found to innervate components of the ascending arousal system, including the tuberomammillary nucleus (TMN) and other components of the lateral hypothalamus; the raphe nuclei; the locus coeruleus (LC); the pedunculopontine (PPT) and laterodorsal tegmental nuclei (LDT); and the parabrachial nucleus (PB). More recent studies using opto- or chemogenetic activation of VLPO neurons have confirmed that they promote sleep.[23]

The sleep-promoting effects of the VLPO neurons is thought to be due to release of GABA and possibly galanin that suppresses firing of arousal system neurons. As the VLPO is also inhibited by neurotransmitters released by components of the arousal systems, such as acetylcholine and norepinephrine,[9] a current theory has proposed that the VLPO and the arousal system form a "flip-flop" circuit.[1][2] This term from electrical engineering denotes a circuit in which mutual inhibition means that each component of the circuit, as it turns on, turns the other off, resulting in rapid transitions from one state (wake or sleep) to the other, with minimal time in transition states. This theory has been used to create mathematical models that explain much of the wake-sleep behavior in animals, including in pathological states and responses to drugs.[1][24][25] Orexin neurons in the posterior lateral hypothalamus potentiate neurons in the ascending arousal system and help stabilize the brain in the waking state (and consolidated wakefulness, which builds up homeostatic sleep drive, helps stabilize the brain during later sleep). The loss of orexin neurons in the disorder narcolepsy destabilizes the wake-sleep switch, resulting in overwhelming sleep episodes during the waking day, as well as more frequent awakenings from sleep at night.[1]

Circadian rhythm

[edit]

There is a strong circadian rhythm of sleep in mammals. The “master clock” for circadian rhythms in mammals is the suprachiasmatic nucleus (SCN). The SCN has little if any projection directly to the VLPO neurons. Instead, they project strongly to the adjacent subparaventricular zone, which in turn contains inhibitory GABAergic neurons that innervate the dorsomedial nucleus of the hypothalamus.[26][27] Lesions of the dorsomedial nucleus almost completely eliminate the circadian rhythm of sleep. GABAergic neurons in the dorsomedial nucleus innervate the VLPO, and glutamatergic neurons innervate the lateral hypothalamus, suggesting that the dorsomedial nucleus mainly promotes wakefulness during the active period (daytime for humans).[26]

Clinical significance

[edit]

Insomnia

[edit]

Elderly human patients with more galanin neurons in their intermediate nucleus (the human equivalent of the VLPO galanin neurons in rodents) have better, more continuous sleep. A reduced number of VLPO neurons is associated with more fragmented sleep (more awakenings throughout the night).[28]

Lesions in the VLPO in rats results in 50-60% decrease in NREM sleep time and prolonged insomnia.[29] More recent research suggests that stress-induced insomnia could be due to an imbalance of input to arousal system and VLPO neurons.[30]

Sedative/hypnotic drugs

[edit]

Many sedative/hypnotic drugs act by binding to and potentiating GABA-A receptors. These include older drugs such as ethanol, chloral hydrate and barbiturates, as well as newer benzodiazepines and "non-benzodiazepine" drugs (such as zolpidem, which bind to the same receptor but have a different chemical configuration), and even anesthetics such as propofol and isoflurane. As the VLPO inputs to the arousal system use this same receptor, these drugs at low doses essentially act by potentiating the VLPO, producing a sleepy state. Animal studies show that VLPO neurons show cFos activation after sedative doses of these drugs,[31] and that VLPO lesions produce resistance to their sedative effects.[32] However, at high doses that produce a surgical plane of anesthesia, these drugs have much more widespread inhibitory effects, that do not depend upon the VLPO.[33] Studies have shown that multiple sedative/hypnotic drugs that act by potentiating GABA-A receptors, including ethanol, chloral hydrate, propofol and gas anesthetics such as isoflurane, at sedative doses increase the activity of the VLPO neurons in mice.[34] This finding suggests that at relatively low sedative doses, these medications may have a common mechanism of action, which includes potentiating the firing of VLPO neurons. High doses used in surgical anesthesia, however, reduce activity of neurons throughout the nervous system.

References

[edit]
  1. ^ a b c d e f Saper CB, Fuller PM, Pedersen NP, Lu J, Scammell TE (December 2010). "Sleep state switching". Neuron. 68 (6): 1023–1042. doi:10.1016/j.neuron.2010.11.032. PMC 3026325. PMID 21172606.
  2. ^ a b c Saper CB, Scammell TE, Lu J (October 2005). "Hypothalamic regulation of sleep and circadian rhythms". Nature. 437 (7063): 1257–1263. doi:10.1038/nature04284. PMID 16251950. S2CID 1793658.
  3. ^ Anaclet C, Ferrari L, Arrigoni E, Bass CE, Saper CB, Lu J, et al. (September 2014). "The GABAergic parafacial zone is a medullary slow wave sleep-promoting center" (PDF). Nat. Neurosci. 17 (9): 1217–1224. doi:10.1038/nn.3789. PMC 4214681. PMID 25129078. In the present study we show, for the first time, that activation of a delimited node of GABAergic neurons located in the medullary PZ can potently initiate SWS and cortical SWA in behaving animals. ... For now however it remains unclear if the PZ is interconnected with other sleep– and wake–promoting nodes beyond the wake–promoting PB. ... The intensity of cortical slow–wave–activity (SWA: 0.5–4Hz) during SWS is also widely accepted as a reliable indicator of sleep need ... In conclusion, in the present study we demonstrated that all polygraphic and neurobehavioral manifestation of SWS, including SWA, can be initiated in behaving animals by the selective activation of a delimited node of GABAergic medullary neurons.
  4. ^ a b Schwartz MD, Kilduff TS (December 2015). "The Neurobiology of Sleep and Wakefulness". The Psychiatric Clinics of North America. 38 (4): 615–644. doi:10.1016/j.psc.2015.07.002. PMC 4660253. PMID 26600100. More recently, the medullary parafacial zone (PZ) adjacent to the facial nerve was identified as a sleep-promoting center on the basis of anatomical, electrophysiological and chemo- and optogenetic studies.23, 24 GABAergic PZ neurons inhibit glutamatergic parabrachial (PB) neurons that project to the BF,25 thereby promoting NREM sleep at the expense of wakefulness and REM sleep. ... Sleep is regulated by GABAergic populations in both the preoptic area and the brainstem; increasing evidence suggests a role for the melanin-concentrating hormone cells of the lateral hypothalamus and the parafacial zone of the brainstem
  5. ^ a b Brown RE, McKenna JT (June 2015). "Turning a Negative into a Positive: Ascending GABAergic Control of Cortical Activation and Arousal". Front. Neurol. 6: 135. doi:10.3389/fneur.2015.00135. PMC 4463930. PMID 26124745. The sleep-promoting action of GABAergic neurons located in the preoptic hypothalamus (6–8) is now well-known and accepted (9). More recently, other groups of sleep-promoting GABAergic neurons in the lateral hypothalamus (melanin-concentrating hormone neurons) and brainstem [parafacial zone; (10)] have been identified.
  6. ^ Oishi Y, Xu Q, Wang L, Zhang BJ, Takahashi K, Takata Y, et al. (September 2017). "Slow-wave sleep is controlled by a subset of nucleus accumbens core neurons in mice". Nature Communications. 8 (1): 734. doi:10.1038/s41467-017-00781-4. PMC 5622037. PMID 28963505. Here, we show that chemogenetic or optogenetic activation of excitatory adenosine A2A receptor-expressing indirect pathway neurons in the core region of the NAc strongly induces slow-wave sleep. Chemogenetic inhibition of the NAc indirect pathway neurons prevents the sleep induction, but does not affect the homoeostatic sleep rebound.
  7. ^ a b Sherin JE, Shiromani PJ, McCarley RW, Saper CB (January 1996). "Activation of ventrolateral preoptic neurons during sleep". Science. 271 (5246): 216–219. doi:10.1126/science.271.5246.216. PMID 8539624. S2CID 19804653.
  8. ^ Brown RE, Basheer R, McKenna JT, Strecker RE, McCarley RW (July 2012). "Control of sleep and wakefulness". Physiological Reviews. 92 (3): 1087–1187. doi:10.1152/physrev.00032.2011. PMC 3621793. PMID 22811426.
  9. ^ a b c d Gallopin T, Fort P, Eggermann E, Cauli B, Luppi PH, Rossier J, et al. (April 2000). "Identification of sleep-promoting neurons in vitro". Nature. 404 (6781): 992–995. doi:10.1038/35010109. PMID 10801127. S2CID 4364527.
  10. ^ Walter A, van der Spek L, Hardy E, Bemelmans AP, Rouach N, Rancillac A (December 2019). "Structural and functional connections between the median and the ventrolateral preoptic nucleus". Brain Structure & Function. 224 (9): 3045–3057. doi:10.1007/s00429-019-01935-4. PMID 31493023.
  11. ^ Scammell TE, Gerashchenko DY, Mochizuki T, McCarthy MT, Estabrooke IV, Sears CA, et al. (2001). "An adenosine A2a agonist increases sleep and induces Fos in ventrolateral preoptic neurons". Neuroscience. 107 (4): 653–663. doi:10.1016/s0306-4522(01)00383-9. PMID 11720788. S2CID 45189308.
  12. ^ a b Gallopin T, Luppi PH, Cauli B, Urade Y, Rossier J, Hayaishi O, et al. (2005). "The endogenous somnogen adenosine excites a subset of sleep-promoting neurons via A2A receptors in the ventrolateral preoptic nucleus". Neuroscience. 134 (4): 1377–1390. doi:10.1016/j.neuroscience.2005.05.045. PMID 16039802. S2CID 27732204.
  13. ^ Scammell T, Gerashchenko D, Urade Y, Onoe H, Saper C, Hayaishi O (June 1998). "Activation of ventrolateral preoptic neurons by the somnogen prostaglandin D2". Proceedings of the National Academy of Sciences of the United States of America. 95 (13): 7754–7759. doi:10.1073/pnas.95.13.7754. PMC 22747. PMID 9636223.
  14. ^ Scharbarg E, Walter A, Lecoin L, Gallopin T, Lemaître F, Guille-Collignon M, et al. (March 2023). "Prostaglandin D2 Controls Local Blood Flow and Sleep-Promoting Neurons in the VLPO via Astrocyte-Derived Adenosine" (PDF). ACS Chemical Neuroscience. 14 (6): 1063–1070. doi:10.1021/acschemneuro.2c00660. PMID 36847485.
  15. ^ Sangare A, Dubourget R, Geoffroy H, Gallopin T, Rancillac A (October 2016). "Serotonin differentially modulates excitatory and inhibitory synaptic inputs to putative sleep-promoting neurons of the ventrolateral preoptic nucleus" (PDF). Neuropharmacology. 109: 29–40. doi:10.1016/j.neuropharm.2016.05.015. PMID 27238836.
  16. ^ a b Sherin J (1998). "Innervation of Histaminergic Tuberomammillary Neurons by GABAergic and Galaninergic Neurons in the Ventrolateral Preoptic Nucleus of the Rat". The Journal of Neuroscience. 18 (12): 4705–4721. doi:10.1523/JNEUROSCI.18-12-04705.1998. PMC 6792696. PMID 9614245.
  17. ^ Scharbarg E, Daenens M, Lemaître F, Geoffroy H, Guille-Collignon M, Gallopin T, et al. (January 2016). "Astrocyte-derived adenosine is central to the hypnogenic effect of glucose". Scientific Reports. 6 (1): 19107. doi:10.1038/srep19107. PMC 4709579. PMID 26755200.
  18. ^ Sangare A, Dubourget R, Geoffroy H, Gallopin T, Rancillac A (October 2016). "Serotonin differentially modulates excitatory and inhibitory synaptic inputs to putative sleep-promoting neurons of the ventrolateral preoptic nucleus" (PDF). Neuropharmacology. 109: 29–40. doi:10.1016/j.neuropharm.2016.05.015. PMID 27238836.
  19. ^ Rancillac A (November 2016). "Serotonin and sleep-promoting neurons". Oncotarget. 7 (48): 78222–78223. doi:10.18632/oncotarget.13419. PMC 5346632. PMID 27861160.
  20. ^ Nauta W (1946). "Hypothalamic regulation of sleep in rats". Journal of Neurophysiology. 9: 285–314. doi:10.1152/jn.1946.9.4.285. PMID 20991815.
  21. ^ McGinty D (1968). "Sleep Suppression after Basal Forebrain Lesions in the Cat". Science. 160 (3833): 1253–1255. doi:10.1126/science.160.3833.1253. PMID 5689683. S2CID 24677928.
  22. ^ Walter A, van der Spek L, Hardy E, Bemelmans AP, Rouach N, Rancillac A (December 2019). "Structural and functional connections between the median and the ventrolateral preoptic nucleus". Brain Structure & Function. 224 (9): 3045–3057. doi:10.1007/s00429-019-01935-4. PMID 31493023.
  23. ^ Kroeger D, Absi G, Gagliardi C, Bandaru SS, Madara JC, Ferrari LL, et al. (October 2018). "Galanin neurons in the ventrolateral preoptic area promote sleep and heat loss in mice". Nature Communications. 9 (1): 4129. doi:10.1038/s41467-018-06590-7. PMC 6175893. PMID 30297727.
  24. ^ Phillips AJ, Robinson PA (April 2007). "A quantitative model of sleep-wake dynamics based on the physiology of the brainstem ascending arousal system". Journal of Biological Rhythms. 22 (2): 167–179. doi:10.1177/0748730406297512. PMID 17440218. S2CID 31817324.
  25. ^ Fulcher BD, Phillips AJ, Postnova S, Robinson PA (2014). Mistlberger RE (ed.). "A physiologically based model of orexinergic stabilization of sleep and wake". PLOS ONE. 9 (3): e91982. doi:10.1371/journal.pone.0091982. PMC 3961294. PMID 24651580.
  26. ^ a b Chou TC, Scammell TE, Gooley JJ, Gaus SE, Saper CB, Lu J (November 2003). "Critical role of dorsomedial hypothalamic nucleus in a wide range of behavioral circadian rhythms". The Journal of Neuroscience. 23 (33): 10691–10702. doi:10.1523/jneurosci.23-33-10691.2003. PMC 6740926. PMID 14627654.
  27. ^ Vujovic N, Gooley JJ, Jhou TC, Saper CB (December 2015). "Projections from the subparaventricular zone define four channels of output from the circadian timing system". The Journal of Comparative Neurology. 523 (18): 2714–2737. doi:10.1002/cne.23812. PMC 4607558. PMID 26010698.
  28. ^ Lim A (2014). "Sleep is related to neuron numbers in the ventrolateral preoptic/intermediate nucleus in older adults with and without Alzheimer's disease". Brain. 137 (Pt 10): 2847–61. doi:10.1093/brain/awu222. PMC 4163039. PMID 25142380.
  29. ^ Lu J, Greco MA, Shiromani P, Saper CB (May 2000). "Effect of lesions of the ventrolateral preoptic nucleus on NREM and REM sleep". The Journal of Neuroscience. 20 (10): 3830–3842. doi:10.1523/jneurosci.20-10-03830.2000. PMC 6772663. PMID 10804223.
  30. ^ Cano G, Mochizuki T, Saper CB (October 2008). "Neural circuitry of stress-induced insomnia in rats". The Journal of Neuroscience. 28 (40): 10167–10184. doi:10.1523/JNEUROSCI.1809-08.2008. PMC 2693213. PMID 18829974.
  31. ^ Lu J, Nelson LE, Franks N, Maze M, Chamberlin NL, Saper CB (June 2008). "Role of endogenous sleep-wake and analgesic systems in anesthesia". The Journal of Comparative Neurology. 508 (4): 648–662. doi:10.1002/cne.21685. PMC 4924624. PMID 18383504.
  32. ^ Moore JT, Chen J, Han B, Meng QC, Veasey SC, Beck SG, et al. (November 2012). "Direct activation of sleep-promoting VLPO neurons by volatile anesthetics contributes to anesthetic hypnosis". Current Biology. 22 (21): 2008–2016. doi:10.1016/j.cub.2012.08.042. PMC 3628836. PMID 23103189.
  33. ^ Eikermann M, Vetrivelan R, Grosse-Sundrup M, Henry ME, Hoffmann U, Yokota S, et al. (December 2011). "The ventrolateral preoptic nucleus is not required for isoflurane general anesthesia". Brain Research. 1426: 30–37. doi:10.1016/j.brainres.2011.10.018. PMC 3215917. PMID 22041226.
  34. ^ Moore J (2012). "Direct Activation of Sleep-Promoting VLPO Neurons by Volatile Anesthetics Contributes to Anesthetic Hypnosis". Current Biology. 22 (21): 2008–2016. doi:10.1016/j.cub.2012.08.042. PMC 3628836. PMID 23103189.
[edit]
Retrieved from "https://en.wikipedia.org/enwiki/w/index.php?title=Ventrolateral_preoptic_nucleus&oldid=1248364223"