Cholinergic projections from the basal forebrain of rat to the amygdala

Cholinergic afferents to the amygdala from the basal forebrain were studied using di-isopropyl fluorophosphate-AChE histochemistry in combination with retrograde tracing using various fluo-rescent dyes. Cells sending their axons to the amygdala and staining intensely for AChE were located mainly in the nucleus of the substantia innominata. They also were found in the ventral part of the globus pallidus, the horizontal limb of the nucleus tractus diagonalis Broca, and the nucleus interstitialis ansae lenticularis. A correspondence was established between these cells and cells staining for choline acetyltransferase by immunohistochemistry in both distribution and morphology. Non-cholinergic neurons which send their axons to the amygdala also were found in the substantia innominata complex. It has been well established that there is a high con-centration of “marker ” enzymes for cholinergic neurons, i.e., choline acetyltransferase (ChAT) and AChE, in the amygdaloid complex (Palkovits et al., 1974; Ben Ari et al., 1977). Recently, immunohistochemical staining usin