Localization of isoenzymes II/III of protein kinase C in the rat visual cortex (area 17), hippocampus and dentate gyrus.

Monoclonal antibodies against type II and type III subspecies of protein kinase C PkC(II/III) were used to map the distribution of these isoenzymes in the visual cortex (area 17), hippocampus and dentate gyrus of the rat. PkC(II/III)-immunocytochemistry resulted in a specific staining of neuropil and of neuronal somata with their proximal dendrites. The majority of immunopositive cells exhibited a punctate distribution of reaction product, while only a few neurons were homogeneously labeled. In the visual cortex stained neurons were distributed throughout all laminae and reached a particularly high density in layers II/III. Moreover, PkC(II/III)-positive neurons were found within the strata pyramidale and radiatum of the hippocampus proper and in the stratum granulosum, the subgranular zone and the hilar region of the dentate gyrus. The present results suggest that PkC(II/III)-positive neurons constitute a distinct population of both projection and local circuit neurons that are not exclusively associated with any one neurotransmitter system.