Expression of peroxisome proliferator-activated receptors is regulated by gonadotropins and steroid hormones in in vitro porcine ovarian follicles

Abstract

The peroxisome proliferator-activated receptors (PPARs) are a family of transcription factors which are involved in the regulation of different processes such as lipid metabolism, inflammation, angiogenesis, tissue remodeling and steroidogenesis. Our previous data described the ovarian expression of PPAR isoforms (-α, -γ and -β), and the increase of PPAR-α and PPAR-γ in porcine ovarian follicles during the estrous cycle. The current studies were undertaken to test the hypothesis that gonadotropin and steroid hormones can regulate the expression of PPAR isoforms in the ovary. Medium follicles (4 - 6 mm) at 10 - 12 days of the estrous cycle were obtained from mature crossbred gilts. Ovarian follicles were exposed to gonadotropins FSH and LH at 50, 100 and 150 ng/ml, and to steroid hormones such as progesterone (P4), testosterone (T) and estradiol (E2) at 10^-8, 10^-7, 10^-6 M for 24 hours. Then mRNA and protein expression of PPAR-α/γ/β via real time PCR and Western blot, respectively, were measured. We observed that FSH increased both mRNA and protein expression of all PPAR isoforms, while LH only increased PPAR-α/γ. We have also noted that P4 and E2 significantly increased expression of PPAR-α/γ without having an effect on β isoform, while T had no effect on all PPARs expression. Our study clearly showed that local regulators of ovarian activity, both gonadotropin and steroid hormones are regulators of PPAR isoforms expression in porcine ovarian follicles.