Duration of the luteotrophic memory of the stud male odors formed in the female mouse

Abstract

Presence of the stud male prevents the novel male-induced block to early pregnancy in mice, while reexposure to the stud male after the pregnancy block induces pseudopregnancy in the females. These two phenomena involve luteotrophy in the female, and a (luteotrophic) memory of the stud male characteristics formed in her is necessary for such a luteotrophic response. Two experiments were conducted to evaluate the effective duration of the "luteotrophic memory" of the stud male odors formed in the female mouse. The first experiment investigated whether exposure to excreta of the stud male at different intervals will induce pseudopregnancy in pregnancy-blocked females; some females mated with a second male and experienced a second consecutive pregnancy failure before the exposure to the excreta of the first stud male. The females, mated once or twice, failed to exhibit pseudopregnancy when exposure to the excreta of the first stud male was begun 8 or 9 days after the first mating. In the second experiment, each pregnancy-blocked female was mated with the (alien) male that induced failure of the first pregnancy and then housed with simultaneous access to the excreta of another alien male and that of the first stud male. Excreta of the first stud male did not prevent failure of the second pregnancy. The results indicate that the (luteotrophic) memory of the stud male-originating olfactory cues formed in the female or its effectiveness in reactivating the luteotrophic system (when the female is reexposed to the odors of the first stud male) lasts only up to about day 7 postcoitum. The present results also show that exposure to only the excreta of the stud male can prevent the pheromonal block to pregnancy or induce pseudopregnancy after pregnancy block in the female mouse.