Assessment of Sertoli cell functional reserve and its relationship to sperm parameters

Sertoli cell functional reserve was assessed in normozoospermic men and oligozoospermic patients and its prognostic potential was evaluated for patient selection and treatment. For the first objective, three groups of normo-follicle-stimulating hormone (FSH)/normozoospermic fertile men (n:12), normo-FSH/oligozoospermic (n:21) and hyper-FSH/oligozoospermic subfertile men participated in the study whereas for the second objective 24 normo-FSH oligozoospermic patients volunteered for a pilot therapeutic trial. For the first part, high purity (hp) FSH (225 i.u., i.m.), human chorionic gonadotropin (hCG) (1500 i.u., i.m.) or their combination was given separately at weekly intervals, with samplings at 0, 3, 24 and 48 h. For the pilot trial, rec-FSH (150 i.u./48 h, i.m.) or placebo were prescribed for 6 months. The main outcome measures for the study were inhibin-B (inh-B), insulin-like growth factor (IGF)-I, testosterone and oestradiol concentrations and the main sperm parameters. Bolus administration of hp-FSH or hp-FSH/hCG combination in normozoospermic men resulted in a significant rise of inh-B in normozoospermic men (mean +/- SD, basal: 183.8 +/- 24.2 pg/mL in hp-FSH and 175.2 +/- 23.5 in hp-FSH/hCG treatment; 48 h: 256.1 +/- 34.2 and 246.3 +/- 19.0, respectively, p < 0.001 for both). In oligozoospermic groups basal inh-B concentration was lower than in normozoospermic men (normo-FSH: 117.4 +/- 16.5, hyper-FSH: 81.2 +/- 19.8, p < 0.001 for both) with a post-stimulation increase noted only in normo-FSH patients (hp-FSH 24-h: 132.8 +/- 19.7, p < 0.01; hp-FSH/hCG 0 min: 105.7 +/- 20.1, 24-h: 119.5 +/- 20.6, p < 0.05). Total sperm number and progressive motility showed significant improvements (p < 0.05 for both) after 6 months of rec-FSH treatment in the group of patients with a satisfactory response to hp-FSH stimulation. In conclusion, the basal and reserve activity of Sertoli cells, as judged by inh-B secretion, was higher in normozoospermic than in dyspermic men, with a better therapeutic outcome noted in those patients with an adequate response to hp-FSH stimulation.