CIRCADIAN RHYTHM OF PLASMA TESTOSTERONE IN THE MALE DJUNGARIAN HAMSTER (PHODOPUS SUNGORUS)

Abstract
A marked circadian rhythm of plasma testosterone was found in male Djungarian hamsters. Maximal values in the evening just prior to activity onset were about 12 times higher than minimum values in the early morning. The peak of serum testosterone concentration coincides with onset of oestrus in females.