Immunocytochemical localization of atrial natriuretic factor, galanin and calcitonin gene-related peptide within the rat interpeduncular nucleus.

The immunocytochemical localization of atrial natriuretic factor (ANF), galanin (GAL), and calcitonin gene-related peptide (CGRP) in specific subnuclei of the interpeduncular nucleus (IPN) was determined by immunocytochemistry in rats with and without intraventricular colchicine injection. ANF-positive processes were present within the ovoid regions of the rostral subnucleus, the dorsal lateral subnuclei, and were densely concentrated along the medial aspects of the lateral subnuclei in the caudal half of the IPN. GAL-positive processes were concentrated within the lateral subnuclei, in a narrow band extending over the central and intermediate subnuclei, and within the central subnuclei. GAL-positive cell bodies were present in a narrow band ventral to the rostral subnucleus, and in the ventrolateral corners of the caudal IPN. CGRP-positive processes were primarily localized within the dorsal lateral subnuclei and dorsal aspects of the lateral subnuclei. The presence of ANF, GAL and CGRP peptides within the IPN in patterns similar to previously described localizations of substance P, vasoactive intestinal peptide, serotonin and Leu-enkephalin provides a morphologic basis for modulation of complex physiological actions yet to be elucidated.