Possible involvement of Melanin-Concentrating Hormone in somatic growth in Cichlasoma dimerus.

PEREZ SIRKIN, DANIELA; CÁNEPA, MAXIMILIANO; PANDOLFI, MATÍAS; VISSIO, PAULA G.

Huerta Grande, Córdoba

Congreso; IRCN First Joint Meeting of the Argentine Society for Neurosciences (SAN) and the Argentine Workshop in neurosciences (TAN); 2009

Argentine Society for Neurosciences (SAN) and the Argentine Workshop in neurosciences (TAN)

In vertebrates, hypothalamus produces neuropeptides that stimulates (orexigenic) or inhibits (anorexigenic) food intake. Melanin-concentrating hormone (MCH) is a neuropeptide synthesized in the hypothalamus and is related to body color regulation in non mammals. In mammals, it is implicated in feeding behaviour and energy homeostasis. In teleost fish, contradictory results were found, while in goldfish MCH has an anorexigenic function, in barfin flounder has an orexigenic one. The aims of the present study were: 1) To examine the distribution of MCH in relation to two classical orexigenic neuropeptides: orexin and neuropeptide Y (NPY), 2) To examine the effect of fasting over on MCH brain expression and 3) To examine the effect of background colour (white background (WB): high MCH levels and black background (BB): low MCH levels) on somatic growth. C. dimerus was chosen as experimental model since shows dramatic colour changes under different environmental and physiological conditions. The full length sequence of MCH (GQ253057) and the phylogenetic analysis shows that C. dimerus is close similar to barfin flounder and is high distant to goldfish. The MCH, orexin and NPY neurons and fibers show and overlap distribution in some regions of the hypothalamus suggesting interactions among them. The fasted fish showed an increased MCH expression compared with the fed fish suggesting an orexigenic function. Finally juvenile animals reared in WB showed an augment in somatic growth compared with BB-reared animals (p< 0.05). These results suggest that MCH, together with orexin and NPY, regulates appetite leading to an augment in somatic growth.