SEQUENTIAL RELATIONSHIP BETWEEN ACTIONS OF CRF AND PGE(2) IN THE BRAIN ON SPLENIC SYMPATHETIC-NERVE ACTIVITY IN RATS

An infusion of corticotropin-releasing factor (CRF, 0.1-5.0 mu g/10 mu l/rat) into the third cerebral ventricle (i.c.v.) for 10 min increase d the splenic sympathetic nerve activity in a dose-dependent manner in urethane + alpha-chloralose anesthetized rats. No changes in the arte rial blood pressure and body temperature were observed. The CRF (1.0 m u g/10 mu l)-induced enhancement of the splenic sympathetic nerve acti vity was completely blocked by an i.c.v. pretreatment with a CRF antag onist, alpha-helical CRF9-41 (alpha-hCRF, 10 mu g/10 mu l). The increa se in the splenic sympathetic nerve activity induced by CRF was not bl ocked by pretreatment with a cyclooxygenase inhibitor, sodium salicyla te (100 mu g/10 mu l). In contrast, the splenic sympathetic nerve acti vity also increased after an i.c.v. injection of prostaglandin E-2 (PG E(2), 1 ng/10 mu l) and the increase was completely blocked by i.c.v. pretreatment with alpha-hCRF, These findings suggested a sequential re lationship between actions of CRF and PGE(2), with an activation of PG E(2) system followed by that of CRF system in the brain resulting in a n increase in the splenic sympathetic nerve activity. (C) 1997 Elsevie r Science B.V.