Effects of vitamin E on nicotine-induced lipid peroxidation in rat granulosa cells: Folliculogenesis.

In this study, we investigated the mechanism of oxidative damage induced by nicotine and the efficacy of vitamin E, an integral component of cellular membranes, against the damage in follicular/granulosa cells of rat ovaries. The animals were randomly divided into 4 groups; control, nicotine, nicotine + vitaminE, vitamin E (n = 8, per each group). Nicotine and vitamin E were administrated intraperitoneally 1 mg/kg/day and 200 mg/kg/day, respectively, once daily for 2 weeks. Nicotine increased lipid peroxide levels such as lipid peroxide (LPO) and malondialdehyde (MDA) in serum, 4-hydroxynonenal (4-HNE) in granulosa cells and apoptotic granulosa cells in the ovary. Positive correlation occurred between the findings of LPO markers and TUNEL labeling. Level of 17-β estradiol (E), number of follicles and granulosa cell proliferation decreased with nicotine treatment and negatively correlated with LPO levels and apoptosis in granulosa cells. Ultrastructural study of nicotine treated rat ovaries showed mitochondrial damage and autophagosomes in the granulosa cells. The administration of nicotine and vitamin E together, revealed an increase in E level, granulosa cell proliferation and the number of healthy follicles associated with decrease in LPO, MDA, 4-HNE levels and TUNEL reactivity in a manner correlated with each other, compared to the nicotine group. Vitamin E showed to alleviate mitochondrial damage and decrease the number of autophagosomes in granulosa cells. These results suggest that lipid peroxidation may be one of the nicotine' damage mechanisms on folliculogenesis and vitamin E may prevent nicotine-induced follicular damage through reducing lipid peroxidation level in granulosa cells.