Gonadotrophin receptor expression on human granulosa cells of low and normal responders to FSH

The aim of this study was to determine if follicle stimulating hormone rece ptor and luteinizing hormone receptor (FSH-R and LH-R) expression is altere d on granulosa cells (GC) of women with low oestradiol responses to FSH. Ce lls were obtained from mature follicles (> 17 mm) following controlled ovar ian stimulation. For comparison, chinese hamster ovary (CHO) cells transfec ted with FSH-R or LH-R were also assessed. FSH-R and LH-R expression were d etected by flow cytometry. Receptors were labelled with FSH-R antibodies, o r with excess FSH or human chorionic gonadotrophin (HCG) and anti-FSH or HC G antibodies, and compared to multiple controls. Receptor expression on GCs was more heterogeneous than on CHO cells. Gonadotrophin receptor levels on GCs were not correlated with the number of FSH ampoules administered or pe ak oestradiol response. Low and normal response groups were defined using a ratio of peak oestradiol/number of FSH ampoules. FSH receptor expression w as not different on GCs from low and normal responders. However, LH-R expre ssion was higher on GCs of low responders compared to those of normal respo nders (P = 0.04) suggesting a trend to more advanced luteinization. Access of hormone to follicles was not reduced in low responders. Thus, difference s in gonadotrophin receptor expression, hormone binding, and access of horm ones to follicles do not appear to account for low oestradiol responses to FSH.