Localization of prolactin binding sites in ring dove brain by quantitative autoradiography

Specific binding sites for prolactin have been previously detected and characterized in ring dove brain membranes. In order to map the distribution of these sites, specific binding of 125I-ovine prolactin was examined in slide-mounted sections of 6 male and 6 female ring dove brains by in vitro film autoradiography and densitometry. Analysis of 34 brain regions revealed a sex-specific pattern in specific binding activity. Although no significant sex differences were observed in any individual brain region, a trend in this direction was observed in the preoptic area. Specific binding levels in which the lower limit of the 99% confidence interval was greater than zero were detected in choroid plexus, medial habenula, lateral mesencephalic nucleus, hippocampus, parahippocampal area, preoptic area and 4 hypothalamic sites: paraventricular nucleus, ventromedial nucleus, suprachiasmatic nucleus, and tuberal region. Autoradiographic analysis of specific binding in cerebellum, ventromedial hypothalamus, and hippocampus/parahippocampus yielded relative differences that closely approximated those obtained in binding studies on tissue homogenates from these regions. These results suggest possible sites of prolactin action in altering behavioral state and neuroendocrine function in this species.