Protein changes associated with cobalt-induced epileptic activity in rat cerebral cortex.

In cobalt-induced epileptogenic cortex in rats, a marked increase in two proteins of about 84 kDa and 70 kDa, a slight increase in 12-kDa and 10-kDa proteins and a decrease in a protein of about 57 kDa were noted, as determined by SDS-polyacrylamide gel electrophoresis. The initiation of these protein changes was ahead of the generation of epileptogenic activities. The anticonvulsant drugs phenytoin (PHT) and phenobarbital (PB) attenuated the cobalt-induced epileptogenic activities, but failed to suppress the protein changes. Among these proteins, a 70-kDa protein, when injected intracortically into the motor region of the normal rat cerebrum, evoked epileptic discharges on the electrocorticograph and behavioral seizure, which were abolished by prior treatment with PHT or PB. These findings suggest that the above protein changes are not an indirect offshoot of secondary stimulation of neurons by neurotransmitters or neuromodulators, and that P70 may contribute to the generation of epileptic seizure activities.