title: Diurnal variations in plasma testosterone concentrations in the male lesser mouse lemur (Microcebus murinus).
abstract: In 6 isolated adult male lesser mouse lemurs, concentrations of testosterone in plasma were determinated at 6-h intervals over a 24-h period. Blood samples were collected at monthly intervals and for a period of 12 months under natural photoperiod. In this nocturnal prosimian, there were no apparent diurnal changes in testosterone concentrations during the non-breeding season (autumn). During seasonal sexual activity (January-August), diurnal changes in testosterone concentrations were characterized by a significant rise during the light phase. The daily testosterone peak occurred about 8.5 h after sunrise from February to July, but at the beginning (January) or at the end (August) of the breeding season, the daily testosterone peak was displaced to the morning. A circannual testosterone rhythm occurred with the highest testosterone values in May/June and the lowest values 6 months later. The dramatic fall in testosterone concentrations after the summer solstice may be associated with a change in the peripheral metabolism of testosterone.
mesh_terms: D000818:Animals; D002940:Circadian Rhythm; D007900:Lemur / Q000097:blood*; D007901:Lemuridae / Q000097:blood*; D008297:Male; D011863:Radioimmunoassay; D012621:Seasons; D013739:Testosterone / Q000097:blood*
chemical_list: D013739:Testosterone