DISTRIBUTION OF BETA-ENDORPHIN-LIKE IMMUNOREACTIVE STRUCTURES IN THE CHICKEN AND QUAIL BRAIN AS DEMONSTRATED WITH A NEW HOMOLOGOUS ANTIBODY-DIRECTED AGAINST A SYNTHETIC PEPTIDE

A polyclonal rabbit antibody was raised against a synthetic peptide fr agment located at the C-terminal end of turkey beta-endorphin (beta-EN D) and used to analyze the distribution of beta-END-immunoreactive-lik e structures in the quail and chicken brain. Three major groups of imm unopositive cells were detected in the preoptic area-hypothalamus comp lex. A thin layer of immunopositive cells was parallel and adjacent to the ventral edge of the brain in the preoptic and anterior hypothalam ic region, a more numerous group of immunoreactive perikarya was locat ed along the walls of the third ventricle in these same regions, and, finally, a few scattered cells were found in a more lateral position o n both the internal and external sides of the tip of the fasciculus pr osencephali lateralis. The periventricular cell population extended in the caudal direction until the posterior hypothalamus. Labelled fiber s were always associated with these immunoreactive perikarya, and they were also found in the adjacent hypothalamic regions. A dense innerva tion of the median eminence was also detected. These data are compared with previous studies in mammals and birds that had identified more r estricted populations of immunoreactive cells and the possible sources of the observed discrepancy are discussed. The functional significanc e of the present data is also briefly analyzed. (C) 1994 Wiley-Liss, I nc.