Gonadotropin-releasing hormone positively regulates steroidogenesis via extracellular signal-regulated kinase in rat Leydig cells

Gonadotropin-releasing hormone （GnRH） is secreted from neurons within the hypothalamus and is necessary for reproductive function in all vertebrates. GnRH is also found in organs outside of the brain and plays an important role in Leydig cell steroidogenesis in the testis. However, the signalling pathways mediating this function remain largely unknown. In this study, we investigated whether components of the mitogen-activated protein kinase （MAPK） pathways are involved in GnRH agonist （GnRHa）-induced testis steroidogenesis in rat Leydig cells. Primary cultures of rat Leydig cells were established. The expression of 3β-hydroxysteroid dehydrogenase （3β-HSD） and the production of testosterone in response to GnRHa were examined at different doses and for different durations by RT-PCR, Western blot analysis and radioimmunoassay （RIA）. The effects of GnRHa on ERK1/2, JNK and p38 kinase activation were also investigated in the presence or absence of the MAPK inhibitor PD-98059 by Western blot analysis. GnRHa induced testosterone production and upregulated 3β-HSD expression at both the mRNA and protein levels; it also activated ERK1/2, but not JNK and p38 kinase. Although the maximum effects of GnRHa were observed at a concentration of 100 nmnol L-1 after 24 h, activation of ERKI/2 by GnRHa reached peak at 5 min and it returned to the basal level within 60 min. PD-98059 completely blocked the activation of ERKI/2, the upregulation of 3β-HSD and testosterone production. Our data show that GnRH positively regulates steroidogenesis via ERK signalling in rat Leydig cells. ERK1/2 activation by GnRH may be responsible for the induction of 3β-HSDgene expression and enzyme production, which may ultimately modulate steroidogenesis in rat Leydig cells.

Follicle-stimulating hormone autoantibody is involved in idiopathic spermatogenic dysfunction

Aim： To detect the anti-follicle-stimulating hormone （FSH） antibody in idiopathic infertile patients and fertile subjects in order to determine the role of this antibody in patients with spermatogenic dysfunction. Methods： The anti-FSH antibody in serum was detected by an enzyme-linked immunosorbent assay （ELISA）. The functional and structural integrity of the sperm membrane was evaluated with hypo-osmotic swelling （HOS） test and the ultrastructure of the spermatozoa was investigated by transmission electron microscopy （TEM）. Results： The extent of positive FSH antibody in the patients with oligozoospermia and/or asthenozoospermia was significantly higher than that in the fertile subjects and infertile patients with normal sperm concentration and motility, but it was significantly lower than that in the patients with azoospermia. The extent of anti-FSH antibody in the patients with azoospermia was significantly greater than that in patients with oligospermia and/or asthenospermia, infertile people with normal sperm density and motility and fertile people. The hypo-osmotic swelling test showed that the percentage of HOS-positive spermatozoa （swollen） was 45.1% ±3.5% in the FSH antibody-positive group and 59.1% ± 6.2% in the FSH antibody-negative control group. The percentage of functional membrane damage to spermatozoa was significantly higher in the anti- FSH antibody-positive group than in the control group. TEM showed that the outer acrosomal membrane was located far from the nucleus, and detachment of the acrosome was found in the FSH autoantibody-positive group. Conclusion： These data suggest that the presence of anti-FSH antibody is strongly correlated with the sperm quantity and quality in idiopathic male infertility. Anti-FSH antibody may be an important factor causing spermatogenic dysfunction and infertility.