RELATIONSHIP BETWEEN PROSTAGLANDIN-F2-ALPHA AND ENDOGENOUS NITRIC-OXIDE DURING THE CORPUS-LUTEUM REGRESSION IN THE RAT

In a previous report, we demonstrated that endogenous nitric oxide (NO ) produced by ovarian rat tissue is involved in the demise of the corp us luteum. This effect appears to be mediated by modulation of ovarian prostaglandin synthesis, but the sex steroids could also be involved. In the present study, we investigated the effect of endogenous NO in ovarian rat tissue during luteal regression and its possible correlati on with prostaglandin F-2 alpha (PGF(2 alpha)) synthesis and luteal st eroidogenesis. By means of a competitive nitric oxide synthase (NOs) i nhibitor (N-beta-monomethyl-L-arginine; L-NMMA) (3000 mu m) we demonst rated that during the luteolytic phase, endogenous NO inhibited proges terone production and increased luteolytic PGF(2 alpha) synthesis in o varian tissue from pseudopregnant rats.