Rosiglitazone suppresses FSH and IGF-1 induced downstream PI3K/Akt pathway mediated granulosa cell function involving PPARg and PTEN: Potential targets of fertility regulation

Abstract

Nuclear receptor peroxisome proliferative activated receptor gamma (PPARg) is a prominent targeted molecule in ovarian syndrome. Rosiglitazone, a potent drug administered during Polycystic ovarian syndrome (PCOS), executes its effects through this receptor. However, the exact mechanism through which Rosiglitazone induces PPARg and mediates its action in ovary is not well documented. In the present study, we delineated the signaling pathway for Rosiglitazone action in granulosa cell functioning by using buffalo granulosa cell model. Experiments were performed in serum free primary buffalo granulosa cell culture when cells were follicle stimulating hormone (FSH) responsive with pre-ovulatory phenotype. The cells were incubated with Rosiglitazone alone or in combination with FSH (25 ng/ml) and IGF-1(50 ng/ml). Results showed that Rosiglitazone (25 µM) inhibited FSH and insulin like growth factor-1 (IGF-1) induced granulosa cell proliferation, aromatase, GATA-4, IGF-1 mRNA and oestradiol-17β production. Western blot analysis of total cell lysates revealed that Rosiglitazone intervene with the FSH and IGF-1 signaling by decreasing p-Akt. In addition, Rosiglitazone was found to up-regulate PPAR g and (PTEN) in granulosa cells. PPARg antagonist (GW9662) had no effect on p-Akt level, as well as on steroidogenesis. PTEN inhibitor bpV(pic) revived Akt phosphorylation to the level of control. In conclusion, the present study demonstrated that Rosiglitazone attenuated FSH and IGF-1 induced downstream PI3K/Akt pathway mediated granulosa cell function ( proliferation and steroidogenesis) involving PPARg and PTEN . The elucidated signaling pathway and participating molecules, PPARg and PTEN, could be potential targets while developing novel molecules in PCOS management and fertility regulation