title: Melanin-concentrating hormone neurons discharge in a reciprocal manner to orexin neurons across the sleep-wake cycle.
abstract: Neurons containing melanin-concentrating hormone (MCH) are codistributed with neurons containing orexin (Orx or hypocretin) in the lateral hypothalamus, a peptide and region known to be critical for maintaining wakefulness. Evidence from knockout and c-Fos studies suggests, however, that the MCH neurons might play a different role than Orx neurons in regulating activity and sleep-wake states. To examine this possibility, neurons were recorded across natural sleep-wake states in head-fixed rats and labeled by using the juxtacellular technique for subsequent immunohistochemical identification. Neurons identified as MCH+ did not fire during wake (W); they fired selectively during sleep, occasionally during slow wave sleep (SWS) and maximally during paradoxical sleep (PS). As W-Off/Sleep-On, the MCH neurons discharged in a reciprocal manner to the W-On/Sleep-Off Orx neurons and could accordingly play a complementary role to Orx neurons in sleep-wake state regulation and contribute to the pathophysiology of certain sleep disorders, such as narcolepsy with cataplexy.
authors.affiliation: Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada H3A 2B4.
authors.forename: Oum Kaltoum
authors.initials: OK
authors.lastname: Hassani
authors.forename: Maan Gee
authors.initials: MG
authors.lastname: Lee
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Jones
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D007028:Hypothalamic Hormones / Q000378:metabolism*; D007031:Hypothalamus / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008297:Male; D008543:Melanins / Q000378:metabolism*; D008954:Models, Biological; D009474:Neurons / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism*; D000068797:Orexins; D010455:Peptides / Q000737:chemistry; D010907:Pituitary Hormones / Q000378:metabolism*; D051381:Rats; D020318:Rats, Long-Evans; D012890:Sleep / Q000502:physiology; D012895:Sleep, REM / Q000502:physiology; D014851:Wakefulness / Q000502:physiology
chemical_list: D007028:Hypothalamic Hormones; D047908:Intracellular Signaling Peptides and Proteins; D008543:Melanins; D009479:Neuropeptides; D000068797:Orexins; D010455:Peptides; D010907:Pituitary Hormones; C019463:melanin-concentrating hormone