Crowding or ACTH treatment of pregnant mice affects adult copulatory behavior of male offspring.

Sexual behavior of male offspring from female mice chronically crowded during Days 12-17 of pregnancy was investigated. In an 80-min test pairing with a sexually experienced female primed with estradiol and progesterone injections, males from crowded mothers displayed poorer copulation than controls: mount and intromission latencies were longer, number of mounts and intromissions lower, and ejaculations within the test period were abolished. Daily injections of 500 micrograms testosterone propionate improved copulatory vigor in offspring from crowded mothers. A second series of experiments investigated the effects of ACTH treatment of females during the same period of pregnancy. A low dose rate (1 IU injected daily) had little effect but male offspring from females injected daily with 8 IU displayed longer intromission latency and fewer mounts and intromissions than controls. Daily injections of 500 micrograms testosterone propionate improved copulatory vigor, although mount frequency remained depressed. The similarity of the effects on male offspring copulation of crowding their mothers during pregnancy or ACTH treatment during pregnancy suggest mediation by similar mechanisms, implicating involvement of maternal pituitary-adrenocortical secretions during pregnancy in the production of these behavioral deficits. Postnatal influences were minimized by fostering all litters at birth to untreated dams.