Binding of 125I-cholecystokinin-octapeptide in the paraventricular but not the supraoptic nucleus is increased by ovariectomy

Specific, high affinity binding of 125I-cholecystokinin-octapeptide (CCK) in the paraventricular nucleus was found to be confined to the anterior pole of the posterior magnocellular subdivision (PVHpm). Tissue sampled from intact male and female rats revealed only low CCK binding in the PVHpm; however, binding was greatly increased by ovarietomy. By contrast, binding was uniformly high throughout the supraoptic nucleus of intact males and females and was unaffected by ovariectomy. These results are interpreted in terms of the potential influence of CCK and estrogen on neurosecretion of oxytocin and CCK.