NITRIC-OXIDE MEDIATES INCREASED PROSTAGLANDIN-E PRODUCTION BY OOCYTE-CUMULUS COMPLEXES IN THE NON-INSULIN-DEPENDENT DIABETIC RAT

Previous work described an increase in prostaglandin E (PGE) productio n by oocyte-cumulus complexes (OVA) obtained from non-insulin-dependen t diabetic rats. More recently, it has been found that in control OVA nitric oxide (NO) mediates hCG-induced PGE secretion. To determine whe ther increases in PGE secretion by diabetic OVA are mediated by NO, th e present study has evaluated the secretion of PGE by diabetic OVA, cu ltured in the absence or presence of hCG, NO donors (sodium nitropruss ide (NP) and 3-morpholino-sydnonimine-hydrochloride (SIN-1)), and a NO synthase inhibitor (N(G)monomethyl-L-arginine; L-NMMA). hCG, NP and S IN-1 increased PGE secretion by diabetic OVA. L-NMMA did not modify ba sal secretion of PGE by control OVA but lowered PGE production in diab etic OVA to control values. L-NMMA prevented the hCG-induced PGE accum ulation in control and diabetic OVA, and the quantities of PGE produce d were similar to those of control OVA but lower than in diabetic OVA incubated in the absence of hCG. The effect of L-NMMA seems to be spec ific since N(G)monomethyl-D-arginine had no effect. NO synthase activi ty was higher in diabetic ovaries than in controls. The present result s suggest that NO mediates the increased PGE production by diabetic OV A, probably a result of overproduction of NO.