Localization of cholecystokinin receptors on neuronal elements in rat caudate nucleus

Various chemical and physical lesions were employed to elucidate the cellular localization of cholecystokinin (CCK) receptors in the rat caudate nucleus. A wide knife cut severing all caudal afferents reduced caudate CCK receptors by ≈ 25%, indicating that some receptors lie on axons and (or) terminals of neurons originating outside of the caudate. However, most CCK receptors appear to be located on neuronal cell bodies intrinsic to the caudate nucleus, since local injections of kainic acid reduced caudate CCK receptors by ≈75%. These are similar to recent data from our laboratory on the concentrations of CCK receptors in the basal ganglia of patients with Huntington's disease, and suggest that CCK may be involved in the regulation of extrapyramidal motor function.