GLUTATHIONE OXIDATION IS ASSOCIATED WITH ALTERED MICROTUBULE FUNCTIONAND DISRUPTED FERTILIZATION IN MATURE HAMSTER OOCYTES

We hypothesized that depletion of glutathione (GSH) with diamide, a re latively specific GSH oxidant, may alter the meiotic spindle apparatus in mature hamster oocytes. Immunofluorescent analysis of oocytes expo sed to diamide for 1.5 or 3 h revealed time-and concentration-dependen t disruption of spindle morphology accompanied by chromosome clumping. In oocytes first cultured in diamide for 1.5 h and then in diamide-fr ee medium for 1.5 or 3 h, microtubules appeared to repolymerize, but n ormal spindle structure was not regained. HPLC confirmed that diamide oxidized oocyte GSH under conditions identical to those associated wit h spindle-related abnormalities. Exposure of oocytes to 25 or 50 mu M diamide before in vitro fertilization did not affect their ability to undergo fertilization. A significant proportion of the fertilized oocy tes that had been exposed to 50 mu M diamide before insemination exhib ited abnormal multiple female pronuclei with an apparently normal male pronucleus. These observations indicate that mature hamster oocytes a re susceptible to oxidative stress during the critical period that pre cedes fertilization and provide further evidence that GSH plays import ant roles in oocyte spindle function and pronucleus development.