Pregnancy Block Elicited by Urinary Proteins of Male Mice

Abstract
Pregnant mice exposed to male urinary proteins isolated by salting out of excreted urine, bladder urine, or urine from castrated and testosterone-treated males blocked pregnancy in 3-4 days after treatment. Also homogenates of preputial glands evoked the Bruce effect. Females exposed to urinary proteins had shortened oestrous cycle. The results suggest that male mice produce only one pheromone which can evoke different effects depending on a physiological state of the female.