HUMAN CHORIONIC-GONADOTROPIN INDUCES NITRIC-OXIDE SYNTHASE MESSENGER-RNA IN MOUSE PERITONEAL-MACROPHAGES

We examined the effects of human chorionic gonadotropin (hCG) on the p roduction of nitric oxide (NO) by mouse peritoneal macrophages. hCG ha d no effect on NO synthesis by itself, whereas recombinant interferon- gamma (rIFN-gamma) alone had modest activity. When hCG was used in com bination with rIFN-gamma, there was a marked cooperative induction of NO synthesis in a dose-dependent manner. The optimal effect of hCG on NO synthesis was shown at 6 h after treatment with rIFN-gamma. This in crease in NO synthesis was reflected as increased amount of inducible NO synthase (iNOS) mRNA. N-G-monomethyl-L-arginine, and arginase inhib ited rIFN-gamma-plus-hCG-induced NO production. On the basis of these observations, we conclude that hCG activates expression of iNOS mRNA i n mouse peritoneal macrophages accompanied by NO accumulation via path way dependent on L-arginine in the culture medium. (C) 1996 Academic P ress, Inc.