Immunocytochemical localization of the alpha-, beta I-, beta II- and gamma-subspecies of protein kinase C in the monkey visual pathway.

We examined the distribution of alpha-, beta I-, beta II- and gamma-subspecies of protein kinase C (PKC) in the monkey visual pathway, including the retina, the lateral geniculate nucleus (LGN) and the visual cortex (area 17). In the retina, alpha-PKC immunoreactivity was found in cone photoreceptor and in bipolar cells. beta I-PKC immunoreactivity was present in the ganglion cell layer and the optic nerve fibers. The beta II- and gamma-PKCs were not found in the retina. In the LGN, intense gamma-PKC immunoreactivity was found in a part of magno and parvo cells. The LGN was negative for the alpha-, beta I- and beta II-PKC. All four PKC subspecies were present in the visual cortex but the distribution was distinct. The beta I-PKC immunoreactive cells were scattered in all layers, while the alpha-PKC immunoreactive cells were prominent in layers II, III, IVb, IVc and VI, and the beta II-PKC immunoreactive cells were found in layers II, III, IVb and VI. The intense gamma-PKC immunoreactivity was present in the neuropils in layers I, IVa, IVc and VI and also in soma and dendrites in layers II and VI. It thus seems likely that each subspecies plays a specific role in neuronal transmission in the visual pathway.