Localization of mRNAs for novel, atypical as well as conventional protein kinase C (PKC) isoforms in the brain of developing and mature rats

Using in situ hybridization histochemistry, the localization of mRNAs for 10 isoforms of protein kinase C (PKC) in the rat brain was studied at embryonic and postnatal stages. In the embryonic brain, the gene expression was positive only for PKCε, μ, λ, and ζ with the former three more evident: The expression for PKCμ and λ in the ventricular germinal zone and that for PKCε, ζ, and λ in the mantle zone. In the postnatal brain, the expression for PKCδ, η and θ was detected differentially in a few circumscribed loci such as the thalamus, the habenula, the septum, and the cerebellar granule cells, whereas that for the other isoforms was seen widely in various loci of the gray matter with different intensity. The expression in the cerebellar external granule cell layer was positive only for PKCβ (βI and βII), μ, and λ with that for PKCβ confined to its inner zone. There is a general tendency for all PKC isoforms that the expression levels reach at peaks in early postnatal brain and decreases more or less in adult specimens. This is the first report on the spatio-temporal heterogeneity in the gene expression for the whole members of PKC family in the brain throughout development, especially at embryonic days.