Summary. The role of glutathione (GSH) in cellular protection mechanisms in round spermatids from hamsters was studied. Isolated spermatids were largely depleted of GSH by treating the cells for 2 h with the GSH conjugating agent diethyl maleate (DEM). This treatment resulted in a 90% decrease of the cellular GSH content, but did not affect the ATP content. Exposure of isolated spermatids to cumene hydroperoxide (CHP), a compound which is detoxicated by the GSH redox cycle, showed that the cytotoxicity of the peroxide was markedly potentiated by GSH depletion of the cells. The cytotoxicity was reflected by the cellular ATP content. A decrease of the ATP content of the GSH-depleted spermatids was observed at 5–6-fold lower CHP concentrations, as compared to control cells. An increased cytotoxicity in GSH-depleted cells was also observed using 1-chloro-2,4-dinitrobenzene (CDNB), which is a reactive compound that is detoxicated by glutathione conjugation. The induction of single-strand DNA breaks by gamma radiation was 3–5-fold higher in GSH-depleted spermatids as compared to control cells. This radiation-induced damage was estimated under hypoxic conditions (500 p.p.m. O₂ in N₂). GSH depletion did not affect the repair of single-strand DNA breaks following the irradiation. The present results indicate that cellular GSH has an important function in the defence mechanisms of round spermatids against peroxides, electrophilic xenobiotics and radiation-induced DNA damage.

Keywords: glutathione; spermatids; Sertoli cells; gamma-radiation; xenobiotics; hamster

Normally cyclic heifers (n = 34) received 2500 iu pregnant mares' serum gonadotrophin (PMSG) i.m. at day 10 of oestrus, and 15 mg prostaglandin (PG) i.m. at day 12. Thereafter, a monoclonal antibody against PMSG was administered i.v. before (n = 24), at (n = 6) or shortly after (n = 4) the preovulatory LH surge. Peripheral blood concentrations of LH and oestradiol were compared; follicular development was monitored by daily ultrasound scanning; and the numbers of preovulatory-sized follicles and ovulations were counted 96 h after injection of PG following death. Anti-PMSG treatment before the LH surge inhibited the LH surge in 16 heifers (67%). In these heifers, the initial increase in oestradiol concentration upon PMSG stimulation to 167.5 ± 35.0 pmol l⁻¹ was terminated immediately after anti-PMSG treatment and decreased rapidly to basal values, while the number of preovulatory-sized follicles remained constant until 68 h after PG injection; on average 0.4 ± 0.1 ovulations were counted. In the remaining eight heifers, five animals showed an immediate, but temporary, 20–60% drop in oestradiol concentration after anti-PMSG treatment. In all eight heifers 25% of the preovulatory-sized follicles ovulated. Treatment with anti-PMSG at or shortly after the LH surge did not affect the pattern of oestradiol concentration, but a significantly higher ovulation rate was observed in the animals treated shortly after the LH surge: 20.3 ± 2.6 versus 6.3 ± 2.3 in animals treated at the LH surge, which corresponded to 76% and 24% of the preovulatory-sized follicles monitored shortly before the period of multiple ovulations. Thus, neutralization of PMSG at any time before the maximum concentration of the preovulatory LH surge severely suppresses the functionality of the majority or all of the stimulated follicles, which is dependent on the time of injection of anti-PMSG. Although the follicles retain their size, they lose the potential to ovulate. It is concluded that interfollicular asynchrony of development is present at the time the LH surge occurs.