AGING AND ACUTE STRESS DECREASE CORTICOTROPIN-RELEASING HORMONE IN THE OVARY OF THE FISCHER 344 N RAT/

Corticotropin-releasing hormone (CRH), originally isolated from the hy pothalamus, is widely distributed in many extrahypothalamic central ne rvous system sites, and in the periphery. Immunoreactive (ir)-CRH has been identified in rat and human inflammatory sites, in rat testicular Leydig cells, and in rat thecal and stromal ovarian cells. In the cur rent study, we investigated whether aging and stress are associated wi th changes in ovarian ir-CRH in the rat. Healthy young (3-4 mo) and ol d (24 mo) female Fischer 344/N rats (6 per group) were studied in the morning, before and after being stressed by 120 min of immobilization, and were sacrificed by decapitation. Young females were all in proest rous, and old females were in constant anestrous. Pre-immobilization c orticosterone (CORT) levels were similar in both age groups; immobiliz ation produced a dramatic increase in CORT in both groups; however, th e increase was smaller in the old rats, although this did not reach st atistical significance (P < 0.06). Immunoreactive CRH was detected in the ovaries of all rats, and its distribution and intensity were quant ified masked to the age and treatment group, in the theca, granulosa, stroma, and corpus luteum. At baseline, ir-CRH was 50% lower in old th an in young rats in the theca and stroma by both distribution and inte nsity. Stress was associated with a decrease of ir-CRH levels in the t heca in both age groups, albeit to a significantly lesser extent in ol d rats (old 35% versus young 70%). These data suggest a functional and , perhaps, developmental role for ovarian CRH.