EXTRAHYPOTHALAMIC NEUROPHYSIN-CONTAINING PERIKARYA, FIBER PATHWAYS AND FIBER CLUSTERS IN THE RAT BRAIN

Abstract

Immunoreactive neurophysin (Np) is demonstrated by the immunoperoxidase technique not only within neurons of the classical hypothalamo-neurohypophyseal system, but also in extrahypothalamic perikarya and fibers. Np-positive perikarya are found in the triangular nucleus of the septum. Np fimus, and course medially in the ST to the central nucleus of the amygdala. Np fibers are found in the brain stem and spinal cord. Fine caliber Np fibers from the suprachiasmatic nucleus ascend to the medial dorsal thalamus and lateral septum. The presence of Np within neurons implies the presence of either vasopressin or oxytocin. Np-positive fibers in extrahypothalamic sites may interact with non-neurosecretory neurons involved in neuroendocrine regulation, or may serve as yet unknown functions.