title: Diel plasma testosterone rhythms in male Microtus montanus, the montane vole, under long and short photoperiods.
abstract: Diel plasma testosterone rhythms were examined in adult male Microtus montanus, a seasonal breeder which displays nocturnal locomotor activity under long photoperiod and diurnal activity under short photoperiod. Under 16 hr light:8 hr dark (16L:8D), plasma testosterone levels peak during the light at 11.8 ng/ml. Under 8L:16D, plasma testosterone peaks during the dark at 5 ng/ml.
mesh_terms: D000818:Animals; D003411:Arvicolinae / Q000097:blood*; D002940:Circadian Rhythm / Q000187:drug effects*; D008027:Light; D008297:Male; D010507:Periodicity; D013739:Testosterone / Q000097:blood*
chemical_list: D013739:Testosterone