Peptidergic efferents from the intercalated nuclei of the amygdala to the parabrachial nucleus in the rat.

The peptide content of the intercalated nuclei (ICN) of the amygdala and their projection to the parabrachial nucleus was studied in the rat using the combined retrograde transport-immunofluorescence method. Neurotensin, and to a lesser extent, corticotropin-releasing factor and somatostatin, were found within ICN neurons which innervate the parabrachial nucleus. Enkephalin and somatostatin terminals were particularly dense around ICN neurons that project to the parabrachial nucleus. Our results indicate a functional link between the ICN and the lateral subdivision of the central nucleus of the amygdala based on their similar peptidergic projections to the parabrachial nucleus.