Regulatory effects of urinary pheromones on puberty in the mouse

Abstract

Application of 0.03 ml/day of adult male mouse urine to the oral nasal grooves of postweanling female mice accelerated the onset of first estrus by 4-6 days relative to animals similarly exposed to tap water. Exposure to male urine for 3 successive days between the ages of 21-29 days was sufficient to induce earlier puberty. The older the mouse at the time of first exposure to male mouse urine, the faster its subsequent sexual development. Exposure to male urine tended to shorten the interval between vaginal opening and first estrus indicating that the pheromone does not 'trigger' puberty, but instead accelerates the process of sexual maturation. Puberty was hastened by exposure to urine from either preputialectomized male mice or adult male rats, indicating that the preputial gland does not contain the priming pheromone and that the pheromone is not unique to the male mouse. Urine from castrated male mice was ineffective. In contrast to the acceleratory effect of male urine, urine from grouped adult female mice retarded sexual maturation. The urine of both sexes of adult mice therefore contain pheromones that affect sexual development of the female, but the pheromones are opposite in their regulatory effects on puberty. Relationships between body weight and puberty were not consistent among the 3 experiments and the data do not support the concept of a causal relation between puberty and body weight, although under some conditions they are indeed correlated.