Acceleration and delay of sexual maturation in female mice via chemosignals: circadian rhythm effects.

Two experiments tested whether the male urinary chemosignal that accelerates puberty in female mice or the urinary chemosignal from grouped females that delays puberty are affected by circadian rhythms. The experiments also tested whether there is a circadian component for the response system(s) of the young recipient female mice for the onset of first vaginal estrus. Male urine collected at 0600 h was more effective in inducing earlier maturation than urine collected at 0000, 1200 or 1800 h. Urine from grouped females collected at all four times produced significant delays in first estrus, but urine collected at 0000 h produced longer delays than urine from 0600, 1200 or 1800 h. For male urine, application at 0600 h produced significant acceleration relative to urine treatment at 0000, 1200 or 1800 h. No differences were recorded in age of puberty in females treated with urine from grouped females when urine was applied at the four different time points. Possible interpretations of these results involve circadian variations for various hormones and related physiological processes in both donor and recipient mice.