Thyroid stimulating hormone (TSH) receptor on granulosa cells

Abstract

Subclinical hypothyroidism adversely affects ART and pregnancy outcomes. TSH is present in follicular fluid. TSH receptors (TSHR) have been identified in the bovine corpus luteum, rat and human granulosa cells of primary and secondary antral follicles. The TSHR is a G-protein coupled receptor that activates adenylate cyclase to increase cyclic AMP. This investigation evaluates the TSHR in dominant follicles in monkeys and human granulosa cells obtained during retrieval for IVF. We also compared cyclic AMP levels from media of human granulosa cells treated with increasing concentrations of TSH. Basic science research at an academic institution. Monkey ovaries, obtained one day after LH surge were paraffin embedded and serially sectioned. Immunofluorescence (IF) detection was performed using mouse monoclonal anti-TSH receptor antibody and goat anti-mouse IgG with Alexafluor 488 secondary antibody. Human granulosa cells were isolated from follicular fluid aspirates, cultured on fibronectin coated plates overnight, and treated with increasing TSH concentrations for 24 hours. Cyclic AMP was assayed using an EIA kit. Use of the discarded human cells was determined not to be human subjects research by the IRB. Preliminary results reveal the TSHR by IF in monkey dominant follicle granulosa cells, both cumulus and mural, as well as isolated human granulosa cells. Treatment of human granulosa cells with TSH initially increases cAMP (8 fold over control), then decreases with higher TSH concentration (4 fold over control). This is the first report of TSHR presence on the granulosa cells of monkey dominant follicles. The increased cAMP levels in response to TSH stimulation by human granulosa cells suggest the presence of a functional receptor in this in vitro model. Therefore, future studies using cultured human granulosa cells could elucidate a role TSH may have in granulosa cell function.