Cooperative functions of manganese and thiol redox system against oxidative stress in human spermatozoa

AIMS: In this study, the effects of 0.1 mM Mn(2+) on thiol components (total thiols [TSH], glutathione reduced [GSH], glutathione oxidized [GSSG] and redox ratio [GSH/ GSSG]) have been determined in human spermatozoa. SETTINGS AND DESIGN: The subjects of the study were healthy males having more than 75% motility and 80 × 10(6) sperms/mL. MATERIALS AND METHODS: Fresh semen was suspended in phosphate-buffered saline (PBS) (pH 7.2) and this suspension was divided into eight equal fractions. All fractions, control (containing PBS) and experimental (treated/untreated with [ferrous ascorbate, FeAA - 200 FeSO(4) μM, 1000 μM ascorbic acid, nicotine (0.5 mM) and FeAA + nicotine], supplemented/unsupplemented with Mn(2+) [0.1 mM]), were incubated for 2 h at 37°C. These fractions were assessed for determining the thiol components. STATISTICAL ANALYSIS: The data were statistically analyzed by Students “t” test. RESULTS AND CONCLUSIONS: Ferrous ascorbate, nicotine and ferrous ascorbate + nicotine induced oxidative stress and decreased GSH and redox ratio (GSH/GSSG ratio) but increased the TSH and GSSG levels. Mn(2+) supplementation improved TSH, GSH and redox ratio (GSH/GSSG) but decreased the GSSG level under normal and oxidative stress conditions. Thiol groups serve as defense mechanisms of sperm cells to fight against oxidative stress induced by stress inducers such as ferrous ascorbate, nicotine and their combination (ferrous ascorbate + nicotine). In addition, Mn(2+) supplementation maintains the thiol level by reducing oxidative stress.