REGULATION OF THE OVARIAN OXIDATIVE STATUS BY LEPTIN DURING THE OVULATORY PROCESS IN RATS

BILBAO M; DI YORIO M; GALARZA R; CECILIA L. VARONE; ALICIA FALETTI

REPRODUCTION

BIOSCIENTIFICA LTD

Lugar: Bristol; Año: 2015 vol. 149 p. 357 - 366

1470-1626

Leptin exerts both stimulatory and inhibitory effects on the ovulatory process. Here, we investigated whether these opposite effects involve changes in the oxidative status in response to different levels of leptin. To this end, we performed both in vivo and in vitro assays using ovaries of immature rats primed with gonadotropins to induce ovulation. Superoxide dismutase (SOD) and catalase activity, lipid peroxidation, glutathione content, and reactive oxygen species (ROS) were studied as oxidative damage-related parameters. The expression of Bcl-2, Bax and caspase-3 were measured by Western blot as apoptosis-related biomarkers. The acute treatment with leptin, which inhibits ovulation, decreased SOD activity and increased active caspase-3 expression. No differences were found in catalase activity, lipid peroxidation or total glutathione. In contrast, the daily administration of leptin, which induces ovulation, decreased glutathione content, ROS levels, and Bax and active caspase-3 expression, but caused no changes in other parameters. In addition, the daily administration of leptin induced follicular growth, measured by the number of antral follicles in ovarian sections. Using ovarian explant cultures, we found increased Bcl-2 expression and decreased SOD activity at low and high concentrations of leptin, respectively. Thus, leptin can modulate the oxidative status of the ovarian tissue, during the ovulatory process, by acting on different targets according to its circulating levels. At low concentration, leptin seems to have a protective role against the oxidative stress, whereas at high concentrations, this protein seems to be involved in cell death.