Immunodetection of NGF, trkA, p75 and inhibin alpha-subunit in interstitial cells of golden hamsters treated with hCG

The aim of this study was to investigate the effect of luteinizing hormone (LH) surge on expression of nerve growth factor (NGF), trkA, p75 and inhibin alpha-subunit in ovarian interstitial cells of golden hamsters after human chorionic gonadotropin (hCG) treatment. NGF, two NGF receptors (trkA, p75) and inhibin alpha-subunit were immunolocalized by immunohistochemistry, and gonadotropins, steroid hormones and immunoreactive (ir-) inhibin concentrations were measured by radioimmunoassay. Stronger positive staining of NGF, trkA and p75 were found in interstitial cells at 6, 12 and 18 h after hCG injection in the treated group compared with the control groups. Inhibin alpha-subunit staining was found in interstitial cells at 12 and 18 h after hCG injection in the treatment group, but not in the control group. Plasma concentrations of progesterone increased significantly from 6 to 18 h after hCG treatment, whereas plasma concentrations of estradiol-17beta significantly decreased compared with the control group. An increased plasma concentration of FSH and decreased concentrations of ir-inhibin from 6 to 18 h after hCG treatment verified the negative relationship. There were no significant changes in the concentrations of LH in the hCG-treated group. In contrast, the typical preovulatory LH surge was found at 1700 h on day 4 (proestrus) in the control group. These results suggested that LH surge can induce expression of NGF, trkA, p75 and inhibin alpha-subunit in ovarian interstitial cells and that NGF, trkA, p75 and inhibin alpha-subunit may have a paracrine or autocrine role in modulation of ovarian interstitial cell function in golden hamsters.