Characterization of the melanin-concentrating hormone neurons activated during paradoxical sleep hypersomnia in rats.
Although the main nodes of the neuronal network that regulate paradoxical sleep (PS), also called rapid eye movement sleep, have been identified in rodents, it still needs to be more thoroughly described. We have recently shown that 58% of a hypothalamic neuronal population, the melanin-concentrating hormone (MCH) neurons, are activated after a PS hypersomnia and that MCH, when injected intracerebroventricularly, induces a dose-dependent increase in PS. This suggests that MCH plays a role in PS regulation. Two subpopulations of MCH neurons have been distinguished neurochemically, one that coexpresses cocaine and amphetamine-regulated transcript (CART) and sends ascending projections to the septum and the hippocampus, the other, the non-CART MCH neurons, send descending projections to the lower brainstem and the spinal cord. In order to better characterize the PS-activated MCH neurons it is interesting to determine whether they belong to the first, the second, or both subgroups. We therefore undertook an MCH, CART, and Fos triple immunolabeling study in PS hypersomniac rats. We showed that the MCH neurons activated during PS are part of both subpopulations since we found CART and non-CART MCH-activated neurons. Based on these results and the literature, we propose that MCH could be involved in memory processes and in the inhibition of muscle tone during PS.
Hanriot
Lucie
L
Centre National de Recherche Scientifique UMR5167, Université de Lyon, Université Lyon1, Institut Fédératif des Neurosciences de Lyon, Lyon, 69372, France.
Camargo
Nutabi
N
Courau
Anne Claire
AC
Leger
Lucienne
L
Luppi
Pierre Hervé
PH
Peyron
Christelle
C
D000818:Animals; D002452:Cell Count / Q000379:methods; D006970:Disorders of Excessive Somnolence / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology*; D005583:Fourier Analysis; D005786:Gene Expression Regulation / Q000502:physiology*; D007028:Hypothalamic Hormones / Q000378:metabolism*; D007031:Hypothalamus / Q000473:pathology; D008297:Male; D008543:Melanins / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D016761:Oncogene Proteins v-fos / Q000378:metabolism; D010907:Pituitary Hormones / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012892:Sleep Deprivation / Q000150:complications; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein
D007028:Hypothalamic Hormones; D008543:Melanins; D009419:Nerve Tissue Proteins; D016761:Oncogene Proteins v-fos; D010907:Pituitary Hormones; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein; C019463:melanin-concentrating hormone