Evidence for different aetiologies of low estradiol response to FSH: age-related accelerated luteinization of follicles or presence of ovarian autoantibodies.

BACKGROUND: We found granulosa cells of low responders (LR) expressed more LH receptors, suggesting that follicles were more luteinized than normal responders (NR). The objectives were to test the hypothesis that follicles of LR were more luteinized than follicles of NR, and to determine if LR with (LR+) and without (LR-) ovarian antibodies differed. METHODS: Hormone levels and ovarian autoantibodies (OVAB) were measured in follicular fluid from mature follicles (>17 mm), and in serum obtained on the day of oocyte retrieval during controlled ovarian stimulation. The gonadotrophin response was defined as a ratio of peak estradiol/number of FSH ampoules. RESULTS: NR (32.5 +/- 4.6 years; n = 11) were similar in age to LR+ (33.4 +/- 4.2 years; n = 9) and were younger than LR- (37.1 +/- 3.8 years; n = 12) (P = 0.03). Likewise, dehydroepiandrosterone sulphate was lower in LR- compared with LR+ or NR (P < 0.01). FSH, progesterone, inhibin-A and vascular endothelial growth factor levels were higher in follicular fluid of LR than NR. LR- and LR+ differed. For example, the follicular fluid progesterone/estradiol ratio was similar in NR (11.1 +/- 8.9) and LR+ (9.8 +/- 6.6) but was lower than LR- (22.9 +/- 19.6) (P = 0.05). Serum hormone levels did not reflect follicular fluid hormone profiles. CONCLUSIONS: In the absence of ovarian antibodies, low responses are associated with higher age and accelerated luteinization of mature follicles, rather than diminished responsiveness. Ovarian antibody may be an additional tool to predict and individualize treatment regimens in poor responders.

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 receptor and luteinizing hormone receptor (FSH-R and LH-R) expression is altered on granulosa cells (GC) of women with low oestradiol responses to FSH. Cells were obtained from mature follicles (>17 mm) following controlled ovarian stimulation. For comparison, chinese hamster ovary (CHO) cells transfected with FSH-R or LH-R were also assessed. FSH-R and LH-R expression were detected by flow cytometry. Receptors were labelled with FSH-R antibodies, or with excess FSH or human chorionic gonadotrophin (HCG) and anti-FSH or HCG 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 peak oestradiol response. Low and normal response groups were defined using a ratio of peak oestradiol/number of FSH ampoules. FSH receptor expression was not different on GCs from low and normal responders. However, LH-R expression was higher on GCs of low responders compared to those of normal responders (P = 0.04 ) suggesting a trend to more advanced luteinization. Access of hormone to follicles was not reduced in low responders. Thus, differences in gonadotrophin receptor expression, hormone binding, and access of hormones to follicles do not appear to account for low oestradiol responses to FSH.