REGULATION OF OVARIAN ANTIOXIDANT VITAMINS, REDUCED GLUTATHIONE, AND LIPID-PEROXIDATION BY LUTEINIZING-HORMONE AND PROSTAGLANDIN-F2-ALPHA

Reactive oxygen species are generated by the rat ovary, and they evoke marked antigonadotropic responses in ovarian cells. Protection against reactive oxygen species is provided by antioxidants such as vitamins C, E, and A, and reduced glutathione (GSH). Our objectives were to establish the ovarian levels of these antioxidants during development and regression of the corpus luteum of the pseudopregnant rat and to determine whether these levels were changed by an acute treatment with either a luteotropic (LH) or luteolytic (prostglandin [PG] F2-alpha) agent. In addition, we evaluated the extent of oxidative activity in the ovary by determining the level of lipid peroxidation. Follicular development was associated with a significant increase in ovarian levels of vitamin A and GSH, whereas levels of vitamins E and C were unchanged. During the luteal phase, vitamin E levels tended to increase, whereas vitamin A and GSH levels decreased. Luteal regression was associated with a marked increase in ovarian levels of vitamins E and A, whereas GSH levels increased only transiently. Acute treatment with LH in the midluteal phase produced a transient decrease in vitamin C levels that was maximal at 4 h. Luteal vitamin E levels were markedly increased 24 h after LH treatment, whereas vitamin A levels were unchanged, and no evidence of lipid peroxidation was seen. Acute treatment with PGF2-alpha produced a transient decrease in luteal vitamin C levels coincident with transient lipid peroxidation and a sustained fall in serum progesterone levels. Ovarian vitamin A levels were elevated 24 h after PGF2-alpha treatment. In summary, a prominent increase in ovarian vitamin E levels was associated with luteal regression and replicated by LH treatment. A marked increase in vitamin A levels was associated with both follicular development and luteal regression and was mimicked by PGF2-alpha treatment. Although a rapid, transient depletion of vitamin C was produced by both PGF2-alpha and LH, luteolysis and lipid peroxidation were associated uniquely with PGF2-alpha. The results suggest that the antioxidant reserve of the ovary is a dynamic state and may be endocrine-regulated.