Distribution of pro-opiomelanocortin-derived peptides and enkephalins in the rat central nucleus of the amygdala.

The distribution and origin of beta-endorphin (BE) and alpha-melanocyte stimulating hormone (alpha-MSH) terminals was studied in the central nucleus of the rat amygdala (CNA). The distributions of BE and alpha-MSH within the CNA were compared to that of Met- and Leu-enkephalin (ENK). BE and a-MSH terminals were found mainly in the medial subdivision of the CNA, and originated, at least in part, from the arcuate nucleus region of the hypothalamus. ENK terminals were found in both the medial and lateral subdivisions of the CNA, although a considerably higher density of terminals was seen within the lateral subdivision. This differential distribution of proopiomelanocortins and ENKs may reflect different functions for these endogenous opiates in the CNA.