Changes on the reproductive stage of impuber males European sea bass (Dicentrarchus labrax) after administration of recombinant single-chain FSH

Trabajo presentado en el 7º Congresso de la Assiaçao Ibérica de Endocrinologia Comparativa, celebrado en Porto (Portugal), del 6 al 9 de septiembre de 2009Follicle-stimulating hormone is the main gonadotropin stimulating the early stages of gametogenesis. FSH key role is supposed to be the activation of Sertoli cells proliferation as well as the proliferation of germ cells associated to them. It has been suggested that FSH acts on spermatogenesis alone or by its effects on the production and secretion of androgens. Due to the different results obtained in diverse species, its definitive function has not been yet established. In this study we evaluate the effect of a recombinant single-chain FSH on gonad recrudescence of impuber sea bass. Fish were injected at day 0 and 3 with 0.5µg of scFSH produced by CHO cell line; animals injected with culture medium were used as control. FSH effects were analyzed by monitoring changes of plasma 11-ketotestosterone (11-kt) and gonadal morphology. Changes in gene expression of LH receptor, FSH receptor and Anti-Müllerian Hormone were also evaluated by real-time PCR. Three days after the first injection an increase of plasma 11-kt levels was detected being higher than in control groups until day 15. Changes of gonad structure were observed at day 7, where a strong increase of proliferation was detected. As a result, an increment in the number of cyst of spermatocytes and spermatids was observed, as compared to control groups, which remained immature, showing only spermatogonia type A and B. The increase of plasma FSH provoked suppression on Anti-Müllerian hormone encoding transcript and an increase in LHR mRNA. This findings support the probable role of FSH as the initial signal of the spermatogenesis process enhancing cell proliferation via Sertoli cells activation and as androgen inductor via Leydig cells