Distribution of somatostatin in the rat brain: telencephalon and diencephalon.

The distribution of somatostatin (SRIF) was examined using the unlabeled antibody enzyme method of immunocytochemistry on thick 30-50 microns Vibratome sections. The greatest population of SRIF-neurons was observed along the ventricular wall in the preoptic area and anterior hypothalamus. Dense accumulations of fibers were observed in the suprachiasmatic, ventromedial and arcuate nuclei, the internal and external zone of the median eminence, the organum vasculosum of the lamina terminalis and the subfornical organ. Extrahypothalamic sites of SRIF-containing neurons and fibers were also observed throughout the telencephalon. The widespread distribution of SRIF is consistent with radioimmunoassay data and suggests a diverse physiological role for somatostatin.