MESSENGER-RNA LEVELS OF CA2-INDEPENDENT FORMS OF PROTEIN-KINASE-C IN POSTISCHEMIC GERBIL BRAIN BY NORTHERN BLOT ANALYSIS()

To investigate the role of Ca2+-independent forms of protein kinase C (PKC) in ischemic neuronal injury, mRNA expression of PKC was studied by Northern blot analysis. Ischemia was produced in gerbils by 10-min bilateral carotid artery occlusion and was followed by recirculation f or 15 min, 6 h, and 24 h. Brains of postischemic and sham-operated ani mals were removed, forebrains fresh frozen, and processed for Northern blot analysis. Three synthetic oligonucleotide probes based on publis hed cDNA sequences of rat brain PKC for the isozymes delta, epsilon, a nd zeta were utilized for hybridization. Northern blot analysis showed increased hybridization signal for all three PKC isozymes examined in the 6- and 24-h postischemic groups. Of these, the twofold increases in the expression of PKC delta and zeta were statistically significant in comparison to the control. These results suggest that the mRNA lev els of Ca2+-independent forms of PKC, in particular, delta and zeta, a re temporally stimulated by ischemic injury in the brain and may imply an important role of the enzyme in postischemic neuronal damage. Howe ver, since the protein itself was not examined in this study, the sign ificance of the increased expression cannot be ascertained. However, i t may reflect a compensatory response to the loss of PKC reported to o ccur in the reperfusion phase.