O-022 Kisspeptin system and FSH are up-regulated in long-term restricted fed male sea bass Sebastián Escobar1, Alicia Felip1, Silvia Zanuy 1 and Manuel Carrillo1*. 1Instituto Acuicultura Torre de la Sal IATS-CSIC, Castellón, Spain*Corresponding author. Email: m.carrillo@csic.es Under intensive culture sea bass anticipates puberty preventing further normal somatic growth. Changes in energy homeostasis affect reproduction through certain metabolic signals, integrated by the brain, which influence the kiss/gpr54 and GnRH systems and thus puberty. Therefore, a tight connection between feeding, lipid storage and onset of puberty can be established. Thus, two groups of juvenile male sea bass were set up during 14 months, one normally feed and one kept under maintenance feed restriction. The experimental period included pre-gametogenesis (April), early gametogenesis (September), and spawning (January-March). Animals were sacrificed monthly, at critical reproductive times and morphometric indexes, gonadal morphology, brain peptides expression of and hormone plasma levels evaluated. In experimental fish GSI (gonad), IHS (liver) and MFI (fat) decreased drastically. At onset of gametogenesis the testicle of these fish exhibited higher apoptosis than controls. At spawning, their spermiation time was delayed and the rate of running fish was lower compared to controls. Moreover, at this time experimental fish exhibited lower GnRH1 pituitary content than controls resulting in a low synthesis and release of LH and LHR gonadal expression, which very likely decreased plasma sexual steroid levels. Low levels of 11-KT probably accounted for the lower rate of spermiation and the reduced GSI in restricted fed fish. By contrast, plasma FSH and expression of its receptor in testes as well as kisspeptin receptor 2 mRNA expression in the hypothalamus were up-regulated by the restrictive feeding during the breeding season. Thus, although restrictive feeding provoked an important depression of MFI respect to controls it was not able to entirely block gametogenesis but, significantly decreased rates of spermatogenesis and delayed the rhythms of maturation. Summarizing, restrictive feeding had marked effects on the regulation of the GnRH-gonadotropin-kisspeptin systems indirectly or directly affecting the reproductive process. Acknowledgements: LIFECYCLE(FP7-222719-1), PROMETEO/2010/003 and AQUAGENOMICS(CSD2007-00002). JAE-Predoc-CSIC to S.E.

Ponencia presentada en el 8º Congreso de la Asociación Ibérica de Endocrinología Comparada celebrado en Madrid del 5 al 7 septiembre 2011

Peer Reviewed