Pituitary gonadotropins Fsh and Lh drive teleost reproduction but their specific roles are not well established. It has been suggested that Fsh would act at early stages of spermatogenesis and Lh would support the final ones. Here we analyzed the effects of Fsh and Lh administration, alone or sequentially, in immature yearling sea bass at the time of testicular recrudescence. Plasmids coding for Fsh and Lh were administered intramuscularly and their effect on gonad morphology, plasma hormone levels and gonad gene expression analyzed. Sequential exogenous administration of Fsh/Lh significantly increased plasma 11-KT. Fsh treatment resulted in the highest proportion of testes with cysts of spermatocytes, 36 days after first injection instead Lh treated and control fish remained mainly immature. Fsh treatment also increased gene expression of germinal cell markers, such as piwi, pcna and scp3. Lh alone prompted that of steroidogenic enzymes like cyp17a1, cyp17a2 and 3ßhsd. Results allow concluding that Fsh but not Lh triggers spermatogenesis in sea bass, while Lh potentiates the action of Fsh allowing the progression of spermatogenesis.

Resumen del trabajo presentado en el 7th International Symposium on Fish Endocrinology, celebrado en Buenos Aires (Argentina), del 1 al 6 de septiembre de 2012

Supported by MICINN (AGL2008-02937), EU Project LIFECYCLE (FP7-222719-1) and GV REPROBASS (PROMETEO/2010/003).