EFFECT OF INDOMETHACIN ON THE CRH-INDUCED AND VP-INDUCED PITUITARY-ADRENOCORTICAL RESPONSE DURING SOCIAL STRESS

The role of prostaglandins (PGs) on the corticotropin-releasing hormon e (CRH)- and vasopressin (AVP)-induced pituitary-adrenocortical respon se under basal and social stress circumstances was investigated. Crowd ing stress applied for 3 days did not diminish the CRH-elicited cortic osterone response, but it considerably reduced such a response to AVP. In control rats systemic or icy pretreatment with indomethacin, an in hibitor of PGs synthesis, did not affect the corticosterone response t o ip or icy CRH administered 15 min later. By contrast, ip or icy pret reatment with indomethacin considerably reduced the corticosterone res ponse to AVP given by either route in control rats. Similarly, ip pret reatment with indomethacin further reduced the corticosterone response to AVP already diminished by crowding stress. These results indicate that hypothalamic and anterior pituitary PGs are not involved in the C RH-elicited pituitary-adrenocortical response, but they significantly mediate this response to AVP under both basal and social stress circum stances.