PRINCIPAL INVOLVEMENT OF CYCLOOXYGENASE-1-DERIVED PROSTAGLANDINS IN THE C-FOS EXPRESSION OF THE RAT HIND BRAIN FOLLOWING VISCERAL STIMULATION WITH ACETIC-ACID

We investigated the relationship between c-fos expression in the hind brain and peritoneal prostaglandin (PG) synthesis after visceronocicep tive stimulation with acetic acid in rats. Time-course studies on the mRNA expression for c-fos in the hind brain and cyclooxygenase (COX) i soforms in the peritoneal cells, as well as on the peritoneal 6-keto-P GF(1 alpha) accumulation, after stimulation indicated that COX-1 but n ot COX-2 was responsible for the peritoneal synthesis of PGs which wer e suggested to evoke c-fos expression in the hind brain. Pharmacologic al experiments using mofezolac, a preferential inhibitor against COX-1 , and NS-398, a selective inhibitor against COX-2, confirmed the invol vement of COX-1 derived PGs in the induction of c-fos expression in th e hind brain following the noxious stimulation. (C) 1997 Elsevier Scie nce B.V.