Hormonal and Behavioral Characteristics of Prenatally Stressed Female Rats in an Experimental Model of Depression

Changes in behavior and hypothalamo-hypophyseal-adrenal system (HHAC) activity were studied in adult prenatally stressed female rats in an experimental model of depression, i.e., learned helplessness. Females born to intact mothers were found not to form depression-like behavior, as evidenced by the absence of changes in HHAC activity, despite reductions in locomotor activity in the open field and increases in the duration of immobility in the forced swimming test. At the same time, females born to mothers stressed during the last weeks of pregnancy showed changes in behavior and HHAC activity analogous to those found in our previous studies of these animals in the stress-restress paradigm. These results lead to the conclusion that prenatal stress modifies animals’ sensitivity to intense stressors. This is apparent in the specific pattern of HHAC activity after stressing, independently of the type of stress.