STAGES OF ESTROUS MEDIATE THE STRESS-INDUCED IMPAIRMENT OF ASSOCIATIVE LEARNING IN THE FEMALE RAT

EXPOSURE to a stressful event facilitates classical eyeblink condition ing in male rats and impairs conditioning in females. The contribution of stages of estrous to the stress-induced impairment of eyeblink con ditioning was evaluated. Females in proestrus, estrus and diestrus wer e either exposed to an acute stressor of intermittent tailshocks or sw im stress and compared to unstressed females in the three stages. Fema les in proestrus, when estrogen levels are high, acquired the conditio ned response at a facilitated rate relative to females in other stages . However, exposure to a stressor of either intermittent tailshocks or inescapable swim stress severely impaired acquisition in females duri ng proestrus. These results suggest that the enhancing effect of estro gen on procedural memory formation is disrupted by previous exposure t o a stressful event. (C) 1998 Rapid Science Ltd.