Diminished levels of prostaglandin E in type I diabetic oocyte-cumulus complexes. Influence of nitric oxide and superoxide dismutase

In the present work the prostaglandin E (PGE) production by ovulated, immat ure and in vitro matured oocyte-cumulus complexes (OCC) was evaluated in a rat model of type I diabetes induced by streptozotocin (60 mg kg(-1)). A di minished number of ovulated OCC were found in the type I diabetic rat. In c ontrast to the increment in PGE generation found previously in OCC: and emb ryos from type II diabetic rats, it was found that PGE production by type I diabetic OCC was diminished in comparison with the controls. Nitric oxide synthase (NOS) activity is enhanced in proestrous ovaries from type I diabe tic rats, but cGMP levels are diminished. SIN-1 (300 mu M), a nitric oxide donor, significantly enhanced PGE generation by control OCC, but was unable to modify the PGE levels in type I diabetic OCC. L-NMMA, a nitric oxide in hibitor that diminished PGE values in type II diabetic OCC, did not modify PGE generation in either control and type I diabetic OCC. Superoxide dismut ase (SOD, 1000 U mL(-1)), and SOD (1000 U mL(-1)) plus SIN-1 (300 mu M), en hanced PGE generation by both control and diabetic OCC. The present results suggest that even when nitric oxide (NO) is overproduced in diabetic ovari es, the NO-PGE pathway is impaired in type I diabetic OCC. As SOD additions are able to increase PGE generation by diabetic OCC, high concentrations o f foe oxygen radicals might be quenching the NO, impairing its physiologica l functions.