Differences in the expression of inhibin receptors and activin receptors in normal human ovaries and their significance

Abstract

To explore the differences in the expression of inhibin (INH) receptors and activin (ACT) receptors in the follicular/luteinic phase in normal human ovaries and their relationship with female endocrine hormone levels. Real time PCR and immunohistochemistry were used to determine the expression of inhibin receptors (INHR) genes, activin receptors (ACTR) genes. Serum estradiol (E2), follicle stimulating hormone (FSH), luteinizing hormone (LH), INHB, ACTA levels were determined by a solid quantitative sandwich enzyme immunoassay technique (Sandwich ELISA) in 21 women during follicular phase and another 21 women during luteinic phase, the correlations between each gene and each hormone were analyzed. (1) ACT type I and II receptors genes (ACTR I A, ACTR I B, ACTR II A, ACTR II B) and INH receptor beta-glycan genes were expressed higher in the follicular phase than in the luteinic phase: ACTR I A (0.50 +/- 0.17 vs 0.36 +/- 0.18; P < 0.05), ACTR I B (0.050 +/- 0.019 vs 0.036 +/- 0.020; P < 0.05), ACTR II A (0.10 +/- 0.04 vs 0.07 +/- 0.04; P < 0.05), ACTR II B (0.28 +/- 0.10 vs 0.19 +/- 0.11; P < 0.05), beta-glycan (0.26 +/- 0.10 vs 0.17 +/- 0.09; P < 0.01). (2) The intensities of ACTR I A, ACTR II A, beta-glycan immunostaining in human normal ovaries in the follicular phase were significantly stronger compared to those in luteinic phase. In the follicular phase beta-glycan expression was positively correlated with serum E2, FSH, LH, INHB levels. The correlation coefficient was 0.53 (P < 0.05), 0.74 (P < 0.01), 0.85 (P < 0.01) and 0.76 (P < 0.01) respectively. In normal human ovary in the follicular phase INH and ACT bind their receptors and down-regulate or up-regulate FSH, thus influencing the follicular development.