GABA- and peptide-immunoreactivities co-localize in the rat central extended amygdala.

The central amygdaloid nucleus and the lateral bed nucleus of the stria terminalis are two similar telencephalic structures belonging to the central extended amygdala. These regions contain numerous peptidergic and GABAergic neurones which maintain the neurones projecting to the brain stem under tight intrinsic control. Using immunocytochemistry in colchicine-treated rats, we showed that, in the lateral subdivision of the central amygdaloid nucleus and in the dorsal part of the lateral bed nucleus of the stria terminalis, a population of GABAergic neurones is able to co-synthesize either corticotropin-releasing factor or methionine-enkephalin, but never both peptides. These results suggest that, in the GABAergic intrinsic circuits of the central extended amygdala, co-liberated peptides can have a modulatory role on GABAergic actions.