Inhibin B plasma concentrations in oligozoospermic subjects before and after therapy with follicle stimulating hormone

The aim of this study was to investigate inhibin B and follicle stimulating hormone (FSH) secretion in a large group of oligozoospermic subjects affec ted by different degrees of testicular damage, before and after FSH treatme nt. A total of 135 oligozoospermic subjects (sperm count <20 x 10(6)/ml) we re evaluated fur seminal parameters and FSH, luteinizing hormone (LH), test osterone and inhibin B plasma concentrations. Testicular structure was anal ysed with bilateral fine needle aspiration cytology, Inhibin B showed an in verse correlation with FSH, no correlation with sperm concentration and a s ignificant relationship with intratesticular spermatid number, demonstratin g that testicular spermatids play an important role in the control of inhib in B production. Twenty-five subjects with sperm counts <10 x 10(6)/ml were treated with FSH; 11 of these had basal FSH and inhibin B plasma concentra tions in the normal range (group A), while in seven subjects FSH was elevat ed (>7 IU/l) with normal inhibin B (group B), and in seven patients FSH was high and inhibin B reduced (<80 pg/ml) (group C), During treatment, in gro up A patients inhibin B plasma concentrations increased significantly after 2, 3 and 4 weeks of FSH administration and declined thereafter to pre-trea tment concentrations. Groups B and C did not show any modification during t he treatment. In the same period, in group A FSH increased significantly af ter 2, 3 and 4 weeks and subsequently declined, In groups Il and C, FSH inc reased significantly after 2 weeks and remained elevated during the followi ng period. The results of the present study confirm the significant inverse correlation between inhibin B and FSH plasma concentrations in subjects wi th disturbed spermatogenesis, and demonstrate that inhibin B reflects Serto li cell function and their interaction with spermatids, FSH and inhibin B c oncentrations are an expression of the spermatogenic status of seminiferous tubules, FSH treatment seems to modify inhibin B plasma concentrations onl y in subjects with normal basal FSH and inhibin B, independently from the e ffects of this therapy on sperm production.