Relationship between glutathione, nitric oxide and prostaglandin F2 alpha in functional and regressing rat corpus luteum

M.B REARTE; ALICIA. B MOTTA

St John's College, Cambridge, UK

Congreso; 6 th International Congress on the Cell Biology of Reproduction; 2002

Introduction: The mechanism of corpus luteum (CL) regression has been related to an increased generation of reactive oxygen species (ROS)1. Protection against ROS in cells is provided by enzimes, antioxidant vitamins and metabolites, e.g. glutayhione (GSH)2. In previous studies of the mechanism of CL regression we reported that ovarian nitric oxide (NO) increased prostaglandin F2α (PGF2α) and disminshed serum progesterone (P) during luteolysis3. However, at mid stage of CL development ovarian nitric oxide synthase (NOS) activity was unexpectedly found higher than during regression. Thus, we decided to compare the relationship between NO, GSH and PGF2α on ovarian rat tissue with functional and regressing CLs. Methods: Immature female Wistar rats were given 15IU/rat PMSG inducing formation of CL that remained functional for 9±1 days. For inducing luteolysis: rats were injected with a synthetic PGF2α (3mg/Kg-body weight: ILIREN). Ovarian tissues from rats: i) on mid stage of CL development (functional CLs) and ii) with regressing CLs were used. Ovarina explants5 were cultured for 18h with different treatments: a competitive NOS inhibitor (L-NAME:L-nitro-arginine methyl ester: 600µM) or a long-life NO donor (DETA-NONOate: diethyl-aminetriamine: 10-8-10-4M). At the end of the incubation period media were collected for total GSH determination by Tieze method6 and both P and PGF2α by specific radioimmunoassays. Results: In ovarian tissue with functional CLs, L-NAME inhibited both total GSH and P levels. In contrast, DETA-NONOate increased GSH and P production. After luteolysis induced by PGF2α, total GSH was diminished compared with controls, but when L-NAME was added during the incubation period, GSH inhibition was completely abolished. Conclusion: We propose that during early stage of CL development, NO produced by ovarian tissue could increase GSH content. On the contraty, during luteolysis, PGF2α and No productions, would lead to an impairment in GSH production within the ovary. Thses resutls indicate that NO could act with a dual action (protective or pro-oxidant) in the CL development.