Excitant amino acid projections from rat amygdala and thalamus to nucleus accumbens

High affinity uptake of D-[ 3H]aspartate, [ 3H]choline and [ 3H]GABA was examined in synaptosomal-containing preparations of rat nucleus accumbens septi 7 to 10 days after unilateral or bilateral N-methyl-D-aspartate lesions confined to the parataenial nucleus of the thalamus or the basolateral nucleus of the amygdala. Uptake of both D-[ 3H]aspartate and [ 3H]choline was significantly reduced (11% and 14% less than control, respectively) by unilateral lesion of the thalamus, whereas [ 3H]GABA uptake was unaffected. Bilateral thalamic lesions significantly reduced D-[ 3H]aspartate uptake (11% less than control) into homogenates of the nucleus accumbens, whilst [ 3h]GABA uptake was unaltered. D-[ 3H]asparatate uptake was significantly reduced (26% less than control) following unilateral lesion of the amygdala, whereas both [ 3H]GABA and [ 3H]choline uptake were unaffected. Bilateral amygdaloid lesions significantly increased D-[ 3H]aspartate uptake (39% greater than control), whilst uptake of [ 3H]GABA was not affected. The results implicate glutamate and/or aspartate as putative neurotransmitters in afferent projections from the basolateral amygdala and the parataenial thalamus to the nucleus accumbens. Thalamic afferents to the nucleus accumbens may also utilize acetylcholine as their transmitter.