The physiological roles of chicken LHRH-I and -II (cLHRH-I and -II) in the regulation of gonadotrophin release were investigated in the domestic chicken. Measurements of the neuropeptides, using specific radioimmunoassays, in brain sections cut in three planes or in grossly dissected brain areas, showed that cLHRH-II occurs in low amounts throughout the brain whereas cLHRH-I is most abundant in the diencephalon. Within the diencephalon, the largest amount of cLHRH-I occurred in the median eminence of the hypothalamus. The amount of cLHRH-I in the median eminence was higher (P less than 0.05) in laying than in out-of-lay hens. No cLHRH-II was detected in the median eminence in either reproductive state. The amount of cLHRH-I in the hypothalamus was increased (P less than 0.05) in cockerels at the onset of puberty and in somatically immature birds after castration. There were no correlated changes in the amounts of hypothalamic cLHRH-II measured in the same experimental samples. Active immunization of laying hens against cLHRH-I but not against cLHRH-II resulted in the complete regression of the reproductive system and a depression in the concentration of plasma LH. These observations, taken together, suggest that gonadotrophin secretion in the hen is more likely to be directly regulated by cLHRH-I than by cLHRH-II.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.