Intense arousal of novel male mice in proximity to previously inseminated females: Inactivation of males via chlorpromazine does not diminish the capacity to disrupt pregnancy

In the course of investigating early pregnancy disruptions by novel males, intense behavioral interactions and chemical emissions were observed among males housed in proximity to inseminated females. These interactions were e vident despite wire-mesh separations between males and females. Experiments were designed to examine whether such arousal plays a role in pregnancy di sruption. During the first 5 days of pregnancy, inseminated CF-1 strain fem ale mice were either left undisturbed or exposed to novel outbred males. Ph ysical separations between males did not diminish the frequency of pregnanc y disruption. Subsequently, we investigated whether heavy sedation of novel males tia chronic chlorpromazine administration would diminish the capacit y to disrupt pregnancy. Pregnancy was disrupted to the same degree in femal es exposed to drug-treated males and those exposed to alert competing males given vehicle injections. These data show an unprecedented degree, of arou sal and pheromonal emission among competing males but suggest that these fa ctors are not critical for the capacity to disrupt pregnancy.