PRECOCIOUS PUBERTY IN CHICKS (GALLUS-DOMESTICUS) INDUCED BY CENTRAL INJECTIONS OF NEUROPEPTIDE-Y

The objective of the study was to determine the role of neuropeptide Y (NPY) and biogenic amines on the onset of puberty in birds. Male broi ler chicks were administered chronic intracerebroventricular (ICV) inj ections of 5 mug NPY which produced sexually precocious chicks, determ ined by advanced secondary sex characteristics. One or two weeks follo wing the beginning of a series of NPY injections, the preoptic area (P OA), bed nucleus of the pallial commissure (nCPa), paraventricular nuc leus (PVN), and median eminence (ME) were analyzed for biogenic amines . Levels of L-dopa, the precursor of dopamine (DA) were increased with in the ME of chicks that responded to treatments by showing advanced s exual maturation when an amino acid decarboxylase blocker was administ ered prior to sacrifice. The PVN of respondents showed several changes in biogenic amines, while the nCPa displayed a biogenic amine metabol ite of unknown identity which was significantly lower in respondent ch icks. In contrast to mammals, L-dopa was detectable within the nCPa, P VN, and ME regardless of whether an enzymatic blocker of amino acid de carboxylase was administered to chicks prior to sacrifice. Results sug gest that increased brain levels of NPY and DA, the latter specificall y occurring within the ME, are associated with the onset of puberty. D ue to the several significant differences found in biogenic amino leve ls within the PVN of respondent chicks, this nucleus, similar to the M E may be a highly active and integrative neural structure during the o nset of puberty in chicks.