Differential localization of four subspecies of protein kinase C in the rat striatum and substantia nigra

Abstract

The distribution of protein kinase C (PKC) subspecies and their colocalization with neurotransmitters were examined in the rat striatum and substantia nigra (SN), using immunocytochemistry. The α- and βI-PKC immunoreactivies were seen predominantly in the perikarya of the neurons in the striatum and SN. In contrast, the βII- and γ-PKC immunoreactivities were abundant in both the perikarya and the neuropils in the striatum and only in the neuropils in the SN. From electron microscopic studies, the α- and βI-PKC immunoreactivities were seen adjacent to the plasma membrane, while the βII-PKC immunoreactivity was observed in the cytoplasm around the Golgi complex. The γ-PKC immunoreaction was dense throughout the cytoplasm. The double-staining and lesion studies revealed that the α-PKC-immunopositive neurons in the striatum were intrinsic cholinergic neurons, and that most of the α-PKC-immunoreactive neurons in the SN were dopaminergic neurons. The βI-PKC-immunoreactive neurons were intrinsic GABAergic neurons in the striatum. Moreover, most of the βII- and γ-PKC-immunoreactive neurons were medium-sized neurons projecting to the SN, and over 90% of GABAergic neurons in the caudate-putamen contained βII-PKC. The βII-PKC-immunoreactive neurons showed no γ-PKC immunoreactivity, and the γ-PKC-immunoreactive neurons were not βII-PKC immunoreactive. These findings suggest that α-PKC is related to the function of the nigral dopaminergic and the striatal cholinergic neurons, and that the βI-PKC is involved in the function of the striatal intrinsic GABAergic neurons. The βII- and γ-PKC may also modulate a specific neuronal function in the striatonigral system.