NITRIC-OXIDE MEDIATES HUMAN CHORIONIC GONADOTROPIN-INDUCED PROSTAGLANDIN-E GENERATION IN RAT OOCYTE-CUMULUS COMPLEXES

To determine whether nitric oxide (NO) generation mediates human chori onic gonadotrophin (hCG)-induced prostaglandin E (PGE) secretion by oo cyte-cumulus complexes (OCC), the secretion of PGE by cultured rat OCC in the presence of NO donors and NO synthase (NOS) inhibitors was cha racterized. NO donors (sodium nitroprusside and 3-morpholinosydnonimin e-hydrochloride) increased PGE accumulation in OCC to values similar t o those obtained in the presence of hCG. The three NOS inhibitors test ed (N-G-nitro-L-arginine methyl ester, N-G-monomethyl-L-arginine and a minoguanidine) prevented the hCG-induced PGE accumulation in cultured OCC. This effect appears to be specific since D-enantiomers N-G-nitro- D-arginine methyl ester and N-G-monomethyl-D-arginine had no effect. T he present results suggest that NO mediates the hCG-induced accumulati on of PGE in rat OCC, a process which may occur in vivo in preovulator y follicles prior to ovulation.