Effects of MCH and GnRH on somatolactin secretion from the organ-cultured pituitary of Cichlasoma dimerus (Teleostei, Perciformes)

CÁNEPA, MAXIMILIANO; POZZI, ANDREA; MAGGESE, MARÍA CRISTINA; VISSIO, PAULA

Pinamar, Buenos Aires, Argentina

Congreso; XX Reunión anual Sociedad Argentina de Neuroquímica (SAN); 2005

SAN, SAIB, PABMB

Effects of MCH and GnRH on somatolactin secretion from the organ-cultured pituitary of Cichlasoma dimerus (Teleostei, Perciformes) Cánepa, M., Pozzi, A*., Maggese, M.C. & Vissio, P.G. Laboratorio de Embriología Animal, DBBE, *IFIByNE (CONICET), FCEyN, UBA. Ciudad Universitaria, Buenos Aires. Argentina. Mail: paulav@bg.fcen.uba.ar Somatolactin (SL), is a hormone belonging to the GH/PRL family, produced in the pars intermedia of teleost pituitary. The function is uncertain and there is very scarce information on the regulation of SL secretion from the pituitary. Two forms of SL were detected in C.dimerus (32 and 28 kD), the first corresponding to a glycosilated form and the faster migrating band corresponding to a deglycosylated form. By double immunohystochemistry we find a close association between SL cells and both GnRH and MCH fibers. Analysis by immunoblots of in vitro culture of pituitaries of C. dimerus showed on day 2 of culture a depressed SL secretion. Both GnRH and MCH stimulated the SL release in a dose-dependet manner. On the other hand, MCH stimulated a transient release of SL, since after the release we observed a decrease to the basal level, which is reverted by GnRH addition. In all the cases both forms of SL (glycosylated and nonglycosylated) have similar rates of release. Our results demonstrated that MCH and GnRH regulate the SL release. Such hypothalamic regulation implies physiologica