Introduction: Prenatal exposure to physical stress could affect the behavioral function of offspring after birth and also in puberty.The aim of this study was to determine the effect of prenatal exposures to chronic heterogeneous stress on anxiety-like behaviors in adult male offspring in rats.

Materials & methods: In this experimental study, 10 pregnant rats were used in control and stress groups (n = 5). The Stress group was exposed to heterogeneous stress from the day of 9 to 19 of pregnancy (10 days). After the end of pregnancy and childbirth, 10 adult male offsprings from each group were selected, using the elevated plus-maze(EPM), the anxiety-like behaviors were studied.

Findings: Exposure to stress during pregnancy significantly increased the time spent (P<0.001) and the number of entries (P<0.01) into open arms of the elevated plus maze in the offspring's of stress group compared with the control group. While the time spent in the closed arms (P<0.05) significantly decreased than that in the control group. Time to stay in the center, the number of entries into closed arm and delayed to the first entry into the open arm showed no significant difference between the two groups.

Discussion & Conclusions: Exposure to stress during pregnancy reduced anxiety-like behaviors in rats. Probably, the impact of stress during pregnancy on the incidence of these behaviors can change depending on sex and age. More research in this area could help clarify the issue.