title: Daily melatonin injections inhibit short-day-induced testicular regression in hamsters.
abstract: Daily injections of melatonin were found to retard testicular regression in hamsters exposed to LD 10:14, if the injections occurred in the morning (i.e., 0.5 h after lights on), but not if they occurred in the afternoon (i.e., 6 h after lights on). These results indicate that appropriately times injections of melatonin can at least partially block the inhibitory effects of short days on gonadal activity in the photoperiodic hamster.
mesh_terms: D000818:Animals; D002940:Circadian Rhythm; D006224:Cricetinae / Q000502:physiology*; D008027:Light; D008297:Male; D008550:Melatonin / Q000008:administration & dosage / Q000494:pharmacology*; D008647:Mesocricetus / Q000502:physiology*; D009929:Organ Size / Q000187:drug effects; D012669:Seminal Vesicles / Q000033:anatomy & histology; D013737:Testis / Q000033:anatomy & histology / Q000187:drug effects* / Q000502:physiology
chemical_list: D008550:Melatonin