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 hypothalamus, is widely distributed in many extrahypothalamic central nervous 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 current study, we investigated whether aging and stress are associated with changes in ovarian ir-CRH in the rat. Healthy young (3–4 mo) and old (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 proestrous, and old females were in constant anestrous. Pre-immobilization corticosterone (CORT) levels were similar in both age groups; immobilization produced a dramatic increase in CORT in both groups; however, the increase was smaller in the old rats, although this did not reach statistical significance (P < 0.06). Immunoreactive CRH was detected in the ovaries of all rats, and its distribution and intensity were quantified masked to the age and treatment group, in the theca, granulosa, stroma, and corpus luteum. At baseline, ir-CRH was 50% lower in old than in young rats in the theca and stroma by both distribution and intensity. Stress was associated with a decrease of ir-CRH levels in the theca in both age groups, albeit to a significantly lesser extent in old rats (old 35% versus young 70%). These data suggest a functional and, perhaps, developmental role for ovarian CRH.