Demonstration of extrahypothalamic peptide secreting neurons. A morphologic contribution to the investigation of psychotropic effects of neurohormones.

Visualized by immunocytochemistry vasopression and neurophysin are observed in perikarya of the supraoptic and paraventricular nuclei and their fibers going to the neurohypophysis. In addition to these classical sites, vasopressin and neurophysin are located in perikarya of the organum vasculosum of the lamina terminalis and of the suprachiasmatic nuclei. Outside the hypothalamus, neurophysin-positive perikarya are found in the triangular nucleus of the septum which is a part of the limbic system. Vasopressin and neurophysin are contained in two types of extrahypothalamic fibers. Large caliber fibers are found in the amygdala, small caliber fibers in the septum and thalamus. The presence of neurosecretory perikarya and fibers outside the hypothalamus may be related to psychotropic effects of peptide hormones.