Fish reproduction is under the control of pituitary gonadotropins, the follicle stimulating hormone (Fsh) and lutenizing hormone (Lh). Although the structural duality of these hormones is well known, their individual and dual roles are not well establish in most teleost fish. In sea bass, as in other fish species, Fsh would act at early stages of spermatogenesis, whereas Lh would participate on the final events. Here, we aimed to better understand the role of both gonadotropins during gonadal recrudescence in male sea bass. Accordingly, we used a somatic gene transfer technique as an alternative to the traditional hormonal therapies. Intramuscular injections with plasmids containing Fsh or Lh sequences were sequentially administered and their effects on plasma hormone levels and gonad gene expression were evaluated. Exogenous Fsh activated spermatogenesis, and up-regulated the expression of genes involved in this process. Conversely, Lh alone had no relevant effects on the gonadal stage of maturation compared to controls. It can be concluded that Fsh but not LH tiggers spermatogenesis in sea bass, while LH potentiates the actions of Fsh allowing the progression of the spermatogenic process.

Trabajo presentado en el XIII Congreso Nacional de Acuicultura: "En equilibrio con el medio ambiente", celebrado en Barcelona (España), del 21 al 24 de noviembre 2011