Identification of gonadotropin-responsive genes in fish testis

In all vertebrates, the dual function of testis (production of sexual steroids and production of gametes) is mainly regulated by two gonadotropic pituitary hormones, FSH and LH. However, in fish the biological activities of the two hormones are not still clearly delineated and moreover, their molecular mechanisms are yet poorly understood. In this study we investigated the effects of FSH and LH on testicular gene expression, in the rainbow trout, at two developmental stages I-II and III (I: spermatogonia only, II: active spermatogonia proliferation, III: meiosis onset with the appearance of spermatocytes and round spermatids). Testes were collected from all-male population rainbow trout and incubated in six replicates for 96 hours, at 12°C, in the absence or presence of purified salmonid gonadotropins, FSH and LH (500 ng/mL).