Increased protein kinase C isoform γ in the hippocampus of pentylenetetrazol-induced chemoshocked mouse

Abstract

Protein kinase C (PKC) activity, Western blot analysis of PKCα, -β and -γ, endogenous substrate protein phosphorylation and Western blot analysis of neuromodulin were studied in the cortex, striatum, hippocampus and cerebellum of mouse brain after pentylenetetrazol-induced chemoshock. The PKC isozymes and endogenous substrates in the crude cytosolic and membrane fractions of these four brain regions were partially purified by DE-52 columns eluted with buffer containing 100 or 200 mM KCI. Almost the same PKC activity in the cortex, striatum, hippocampus and cerebellum was found. This kinase activity was increased in the membrane fractions of hippocampus from chemoshocked mice, while that in other brain regions was not changed. On further analysis by immunoblotting, this increased activity was found to be due to the increase of PKCγ isozyme. The in vitro phosphorylation of neuromodulin was also found to be increased in the hippocampus of chemoshocked mice, while the level of neuromodulin was not changed after chemoshock. Therefore, an increase of PKCγ alone, but not neuromodulin, in the hippocampus contributed to the increased phosphorylation of this substrate in chemoshocked mice.