Neuroanatomical characterization of the kisspeptin systems in the brain of the european sea bass (D. labrax): GnRH1 interactions

Trabajo presentado en el 8º Congreso de la Asociación Ibérica de Endocrinología Comparada celebrado en Madrid (España) del 5 al 7 septiembre 2011Kisspeptins are a family of peptides involved in the control of reproduction in vertebrates. They were first identified by their capacity to inhibit tumor metastasis through the receptor GPR54. It has been largely demonstrated that the kisspeptin system plays an essential role in the neuroendocrine control of puberty and reproduction by stimulating the GnRH neurons and subsequently releasing gonadotropin hormones. In sea bass, an economically-important marine teleost fish, two ligands and two receptors coded by different genes have been identified and molecularly characterized. However, there are few studies concerning their expression pattern in the fish brain so far. Thus, we report the neuroanatomical distribution of the cells expressing the two kiss genes and their cognate receptors in the brain of adult sea bass by in situ hybridization. Our findings indicate that kiss1-expressing cells are located at the level of the habenular nucleus and the mediobasal hypothalamus where a strong expression of kiss1 messengers is observed just above the pituitary stalk. Additionally, kiss1 messengers were also detected in the pituitary gland. In contrast, kiss2-expressing cells were observed around the nucleus of the lateral recess and in the anterior preoptic areaInterestingly, the kiss1r was also expressed in the habenula but, in addition it was found in the anterior ventral preoptic region. The kiss2r had a much wider expression in the ventral, lateral and dorsal parts of the telencephalon, the entopeduncular nucleus, the preoptic region and the hypothalamus. Double staining showed that GnRH1 neurons express the kiss2r in the anterior ventral preoptic area. In conclusion, this work represents the first neuroanatomical analysis of the kisspeptin systems in the sea bass brain and suggests a critical role of these peptides in the control of reproduction