Evidence for dopamine D-2 receptors on cholinergic interneurons in the rat caudate-putamen

The aziridinium ion of ethylcholine (AF64A) is a neurotoxin that has demonstrated selectivity for cholinergic neurons. Unilateral stereotaxic injection of AF64A into the caudate-putamen of rats, resulted in a decrease in dopamine D-2 receptors as evidenced by a decrease in 3H]-sulpiride binding. Dopamine D-1 receptors, labeled with 3H]-SCH 23390, were unchanged. The efficacy of the lesion was demonstrated by the reduction of Na+-dependent high affinity choline uptake sites labeled with 3H]-hemicholinium-3. These data indicate that a population of D-2 receptors are postsynaptic on cholinergic interneurons within the striatum of rat brain.