Differential distribution of protein kinase C (PKCαβ and PKCγ) isoenzyme immunoreactivity in the chick brain

Abstract

Protein kinase C (PKC) is involved in neural plasticity. The phosphorylation of the myristoylated alanine-rich protein kinase C substrate (MARCKS) in the left intermediate and medial hyperstriatum ventrale (IMHV) of the chick brain has been shown previously to correlate significantly with the strength of learning in filial imprinting. The distribution of PKCα,βI,βII and PKCγ in the brain of 1-day-old dark-reared chicks was determined immunocytochemically, using the monoclonal antibodies MC5 and 36G9, raised against purified PKCαβ and PKCγ, respectively. PKCγ-stained cells were distributed widely in the telencephalon, including all hyperstriatal structures (including the IMHV), the hippocampus, neostriatum, ectostriatum and archistriatum. There were fewer stained cells in the septum and the least cellular staining was in the paleostriatum primitivum. Fluorescent double-labelling with neuron-specific enolase (NSE) and with the glial calcium-binding protein S100 suggested that PKCγ immunoreactivity was present in neurones but not in glia. The distribution of PKCαβ-stained cells was more limited, with staining in the archistriatum, hippocampus and septum but not in the hyperstriatum. However, there was PKCαβ-staining of some fibres in the IMHV (but little elsewhere in the hyperstriatum ventrale), in the neostriatum, paleostriatal complex and the lobus parolfactorius. Double-labelling with NSE and S100 revealed PKCαβ/S100-positive glial cells present in the paleostriatal region only. There was some PKCαβ-staining of putative neurones in the hippocampus, septum and archistriatum. The differential distribution of PKC isoenzymes suggests that in the IMHV some axonal inputs contain PKCαβ whereas some postsynaptic cells contain the γ form of PKC.