ADRENALECTOMY REVERSES STRESS-INDUCED SUPPRESSION OF LUTEINIZING-HORMONE SECRETION IN LONG-TERM OVARIECTOMIZED RATS

An inhibitory effect of stress on reproductive function is well establ ished. This inhibition involves activation of the hypothalamic-pituita ry-adrenal (HPA) axis, which leads to a suppression of LH secretion. I t has been proposed that this suppression is mediated by a direct effe ct of CRF that is independent of glucocorticoid actions. We tested thi s proposition by examining plasma LH levels in adult rats that were bo th ovariectomized (OVX) and adrenalectomized (ADX). Each animal was su rgically implanted with an indwelling atrial cannula and exposed to in termittent foot shock for 100 min. Blood samples were drawn just prior to putting the animals into the test cage and then at 20-min interval s. Results revealed normal castrate levels of plasma LH in both ADX an d ADX/OVX animals prior to shock. A significant shock-induced suppress ion of LH was observed in OVX animals within 20 min after the onset of shock and remained throughout the duration of the session. In contras t, no evidence was obtained for a suppression of LH in OVX/ADX animals at any time point. Additional studies demonstrated a marked suppressi on of LH in experimentally naive OVX/ADX females implanted with cortic osterone capsules for 2 weeks prior to blood sampling. Overall, these results support a primary role for glucocorticoid actions in the stres s-induced inhibition of reproductive function.