Orexin/hypocretin neurons: chemical phenotype and possible interactions with melanin-concentrating hormone neurons.
We showed earlier that a specific neuron population of the rat lateral hypothalamus, differing from the codistributed melanin-concentrating hormone (MCH) neurons, express both dynorphin (DYN) and secretogranin II (SgII) genes. We demonstrated later that this population corresponds in fact to the newly identified orexin/hypocretin (OX/Hcrt) neurons. In the present study, by revisiting the chemical phenotype of these neurons, we confirm that all of them contain DYN B- and SgII-immunoreactive materials. The roles played by these peptide/protein in OX/Hcrt neurons are still unclear. Double immunocytochemical stainings highlight putative somasomatic, axosomatic and axodendritic contacts between OX/Hcrt and MCH neurons. Adding OX/Hcrt to the culture medium of hypothalamic slices from 8-day-old rats results either in a significant increase of MCH mRNA after 24 h survival or a strong fall after 10 days culture. These results taken together suggest that OX/Hcrt can directly and/or indirectly affect MCH expression, and that both OX/Hcrt and MCH neuron populations interact to respond in a coordinated manner to central and peripheral signals.
Bayer
Laurence
L
CNRS FRE 2174, Laboratoire d'Histologie, Faculté de Médecine, Place Saint-Jacques, 25030 cedex, Besançon, France.
Mairet-Coello
Georges
G
Risold
Pierre-Yves
PY
Griffond
Bernadette
B
D000818:Animals; D002352:Carrier Proteins / Q000096:biosynthesis / Q000494:pharmacology*; D002450:Cell Communication / Q000502:physiology; D002864:Chromogranins; D004399:Dynorphins / Q000096:biosynthesis*; D004723:Endorphins / Q000096:biosynthesis*; D007026:Hypothalamic Area, Lateral / Q000166:cytology / Q000187:drug effects*; D007028:Hypothalamic Hormones / Q000096:biosynthesis*; D007150:Immunohistochemistry / Q000379:methods; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008543:Melanins / Q000096:biosynthesis*; D009474:Neurons / Q000378:metabolism* / Q000502:physiology; D009479:Neuropeptides / Q000096:biosynthesis / Q000494:pharmacology*; D000068797:Orexins; D010907:Pituitary Hormones / Q000096:biosynthesis*; D014176:Protein Biosynthesis; D011506:Proteins; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution / Q000502:physiology
D002352:Carrier Proteins; D002864:Chromogranins; D004723:Endorphins; D007028:Hypothalamic Hormones; D047908:Intracellular Signaling Peptides and Proteins; D008543:Melanins; D009479:Neuropeptides; D000068797:Orexins; D010907:Pituitary Hormones; D011506:Proteins; C019463:melanin-concentrating hormone; D004399:Dynorphins; C036200:rimorphin