Galanin lacks binding sites in the porcine pituitary and has no detectable effect on oxytocin and vasopressin release from rat neurosecretory endings

Abstract

High concentrations of immunoreactive galanin-like material in rat hypothalamus, median eminence and neurohypophysis have been reported in the literature suggesting a regulatory role of galanin on hormone release from the anterior and posterior lobe of the pituitary. We studied binding of iodinated galanin to crude membrane preparations from porcine anterior hypothalamus, anterior and neurointermediate lobe of the hypophysis. In contrast to the hypothalamus where specific binding of 125I-galanin was found, there was no displaceable galanin binding in membranes of the anterior or neurointermediate lobe of porcine pituitaries. Effects of galanin on oxytocin and vasopressin release were investigated using isolated neurosecretory endings from rat neurohypophyses. Galanin had no detectable effect on the release of oxytocin or vasopressin.