title: Melatonin does not influence the expression of c-fos in the suprachiasmatic nucleus of rats and hamsters.
abstract: We have assessed whether melatonin can induce c-fos expression at various circadian phases, and whether melatonin can inhibit photically induced c-fos expression in the suprachiasmatic nucleus (SCN) in both rats and Syrian hamsters. Subcutaneous administration of melatonin at a dose of 100 microg/kg neither induced expression of Fos, the protein product of the c-fos proto-oncogene, nor inhibited the expression of Fos-like immunoreactivity (Fos-lir) induced by a light pulse in the SCN of rats and hamsters. In situ hybridization studies also demonstrated the absence of induction by acute melatonin treatments of c-fos mRNA in the SCN. Taken together, these results demonstrate that melatonin effects on SCN cells involve signal transduction pathways that do not include regulation of c-fos gene expression.
authors.affiliation: Department of Psychology, Dalhousie University, Halifax, NS, Canada.
authors.forename: V
authors.initials: V
authors.lastname: Kumar
authors.forename: D M
authors.initials: DM
authors.lastname: Goguen
authors.forename: M E
authors.initials: ME
authors.lastname: Guido
authors.forename: B
authors.initials: B
authors.lastname: Rusak
mesh_terms: D000818:Animals; D002940:Circadian Rhythm; D006224:Cricetinae; D003624:Darkness; D005786:Gene Expression Regulation / Q000187:drug effects; D016762:Genes, fos / Q000187:drug effects*; D017403:In Situ Hybridization; D008027:Light; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D008647:Mesocricetus; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D013045:Species Specificity; D013493:Suprachiasmatic Nucleus / Q000187:drug effects / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects*
chemical_list: D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D008550:Melatonin