Efectos de la castración y administración de esteroides sexuales sobre la regulación del sistema kisspeptina en el hipotálamo de lubinas adultas (Dicentrarchus labrax L.)

Abstract

The existence of two diferent kiss and gpr54 genes, whose products probably play a critical role in the regulation of the gonadotropic axis, has been reported in sea bass (Dicentrarchus labrax L.). To test the hypothesis that sex steroids regulate kiss/gpr54 gene expression, we analyzed the expression of these genes in adult male and female sea bass according to the following experimental design. In the case of males three groups were organized as follows: gonad-intact fish containing empty silastic implants (sham-control), castrated fish (GDX) implanted with either testosterone containing (GDX+T) or empty (GDX-T) silastic implants. In the case of females, three groups were established including: gonad-intact fish containing empty silastic implants (sham-control), castrated fish (OVX) implanted with either estradiol-17beta containing (OVX+E2) or empty (OVX-E2) silastic implants. Blood, brain and pituitary samples were periodically collected after sex steroid replacement for hormonal and molecular analysis. The participation of sexual steroids in the feedback control of the kisspeptin and GnRH/gonadotropin systems are discussed.