Endocrine Abstracts

Background: Polycystic ovary syndrome (PCOS) is a common endocrine disorder, affecting 5–10% of women of reproductive age. The underlying pathogenesis is complex and incompletely understood. There is evidence that gonadotropin and gonadotropin receptor action play a role in the pathogenesis of PCOS with genome wide association studies in PCOS also implicating altered gonadotropin action in the aetiology of PCOS. Furthermore, our recent studies have demonstrated that gonadotrophin receptor signaling is tightly regulated by the endocytic pathway. However, the precise mechanisms resulting in altered gonadotropin receptor activity in PCOS are unclear.

Objectives: 1. To measure gene and protein expression of LH/hCG and FSH receptors in granulosa lutein cells (GLC) from women with and without PCOS. 2. To measure in-vitro second messenger cAMP generation in GLC from women with and without PCOS after treatment with FSH and LH. 3. To assess the role of receptor internalization on signalling in GLC from women with and without PCOS.

Materials and methods: GLC were isolated from follicular fluid collected at the time of oocyte retrieval. RNA was extracted from the cells and gene expression analysed by RT-qPCR. Protein was extracted and expression analysed by immunohistochemistry. GLC were cultured and treated with LH or FSH with or without pre treatment with Dyngo-4a, a dynamin inhibitor, and cAMP assay performed.

Results: Gene and protein expression of LH/hCG receptor and it’s known splice variants were similar in GLC from women with and without PCOS. Gene expression of FSHR was higher in GLC from women with PCOS than controls (4-fold, P<0.05). LH-dependent cAMP levels were significantly higher (2.5 fold, P<0.05) in GLC from women with PCOS compared to control. Pre-treatment of GLCs with Dyngo4a, which inhibits dynamin dependent receptor internalisation, inhibited both LHR and FSHR cAMP generation (70–80%) equally in both control and PCOS.

Conclusion: There is higher FSH receptor expression in GLC from women with PCOS. Although gene and protein expression are similar in normal and PCOS GLC, LH/hCG receptor signal activation in GLC from women with polycystic ovary syndrome is amplified. Receptor internalisation is required for normal cAMP generation in both normal and PCOS GLCs.