QUANTITATIVE DISTRIBUTION OF PROTEIN-KINASE-C ALPHA-MESSENGER RNA, BETA-MESSENGER RNA, GAMMA-MESSENGER RNA, AND EPSILON-MESSENGER RNA IN THE HIPPOCAMPUS OF CONTROL AND NICTITATING-MEMBRANE CONDITIONED RABBITS

We used oligonucleotide in situ hybridization and film autoradiography to quantitate the distributions of protein kinase C (PKC) alpha, beta , gamma, and epsilon mRNAs in subregions of rabbit hippocampus. Levels of each of the hippocampal PKC isozyme mRNAs and patterns of their re gional distributions were remarkably invariant between individuals. Wi thin stratum pyramidale, the highest levels of PKC alpha mRNA were in the CA2 region, while PKC beta mRNA was maximally expressed in CA1, an d PKC epsilon mRNA in CA3; PKC gamma mRNA was abundantly expressed thr oughout Ammon's horn. Previous experiments employing quantitative auto radiography for [H-3]PDBU (Olds et al., Science, 245 (1989) 866-869) r evealed an increase in membrane-bound PKC in the CA1 region of rabbit hippocampus up to 3 days following classical conditioning of the nicti tating membrane response. We report here that there were no difference s in levels of PKC alpha, beta, gamma, or epsilon mRNA between conditi oned and control rabbits in any hippocampal region one day after train ing. These data are consistent with the hypothesis that PKC is post-tr anslationally activated and translocated to the membrane during memory storage.