C-FOS EXPRESSION MEDIATED BY N-METHYL-D-ASPARTATE RECEPTORS FOLLOWINGANODAL POLARIZATION IN THE RAT-BRAIN

c-Fos protein-like immunoreactivity (IR) was investigated in the rat b rain following an application of weak anodal direct current to the sur face of the unilateral sensorimotor cortex in an attempt to elucidate the cellular and molecular bases of central plasticity. Anodal polariz ation resulted in a massive increase in c-Fos protein-like IR in neuro ns of the cingulate, piriform, frontoparietal cortices, and hippocampu s ipsilateral to the polarization. The effects were dependent upon the duration and intensity of currents applied. The time-dependent induct ion of c-Fos protein-like IR was maximal at 1 h, became weaker by 6 h, and almost returned to the baseline within 24 h following polarizatio n. When MK-801 l-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-im hydr ogen maleate], a noncompetitive antagonist for N-methyl-D-aspartate (N MDA) receptors, was injected intraperitoneally, the induction of this nuclear protein was reduced or completely blocked in both hemispheres, except around the polarized point itself, as a function of the time a nd dosage. These results suggest that the proto-oncogene c-fos is rapi dly and transiently activated in the brain following anodal polarizati on and this activation is mediated by NMDA receptors. (C) 1995 Academi c Press,