Prenatal stress alters the developmental pattern of behavioral indices of sexual maturation and copulation in male rats.

Gestation and pre-puberty are critical periods during which several environmental factors can drastically affect the adequate development of subjects. Considering that stress is one of the most common factors to which subjects may be exposed during gestation, the present study evaluated the effects of prenatal stress on the behavioral indices of sexual maturation in male rats, including genital grooming (GG), preputial separation (PS), and spontaneous penile erections (SPE) during puberty, and on copulatory parameters during adulthood. Stress was exerted by immobilizing the female rats once per day for 2h from days 14-21 of pregnancy. The young rats born to the dams in the stressed group (SG) later presented a delayed occurrence of PS with a delayed onset and lower frequency and duration of GG compared to a control group (CG). Less than half of the subjects in SG presented SPE, and those that did showed delayed onset and lower frequency and duration. In adulthood, fewer subjects in SG showed sexual behavior responses (intromission and ejaculation), and their mount and intromission latencies on the first day they ejaculated were longer than those of the CG rats. Findings from this study provide additional evidence that stress caused by immobilization during the third period of pregnancy exerts a negative effect in the short-term (i.e., around puberty) by altering the typical development of GG and SPE and the occurrence of PS, while also demonstrating that this effect persists in the long-term, when it affects the performance of copulatory behavior in mature male rats.