Effects of anodal polarization on protein kinase Cγ (PKCγ) in the rat brain

An anodal direct current of 0.3 microA or 30.0 microA was unilaterally applied for 30 min or 3 hr to the surface of the sensorimotor cortex of rats, and the effects of anodal polarization on protein kinase C (PKCgamma) activity were examined. The brains were processed by means of immunocytochemistry using the monoclonal antibody 36G9 raised against purified PKCgamma. In sham-operated animals, PKCgamma-like-immunoreactivity (PKCgamma LI) was noted in neuronal cytoplasm, as well as in processes in the cerebral cortex and in the hippocampus. Anodal polarization with 3.0 miroA for 30 min resulted in a pronounced increase in the number of PKCgamma-like-positive neurons in accordance with the intensity of immunostaining in the cerebral cortex, and an increase in the polarized hemispheres was highlighted by repeated applications of the currents. Polarization with 0.3 microA for 3 hr also increased the PKCgamma LI, but 0.3 microA for 30 min or 30.0 microA for any duration had no effects. The effect of polarization on PKCgamma activity, as evaluated by the intensity of immunostaining and the number of neurons, began to increase 1 h after polarization, peaked at 3 hr and thereafter decreased to the control levels by 72 hr. These results indicated the involvement of the gamma-isoform of PKC in the neurochemical mechanism of long-standing central and behavioral changes induced by anodal polarization.