The contribution of endogenous mono-ADP-ribosylation to kindling-induced epileptogenesis.

We examined the alteration of endogenous mono ADP-ribosylation in the hippocampus of amygdaloid kindled rats to clarify the neurochemical basis of epilepsy. A significant increase of the ADP-ribosylation on the 38 kDa protein was observed in the hippocampal membrane of the kindled rat. Several antiepileptics (phenytoin, phenobarbital, carbamazepine, sodium valproate) significantly decreased the ADP-ribosylation on the 38 kDa protein and effaced the increase in the kindled group. The ADP-ribosylation was largely increased by sodium nitroprusside, a nitric oxide generating compound, in both the kindled and control groups. Carbamazepine could not affect the ADP-ribosylation in the presence of sodium nitroprusside. Twenty amino acids from the N-terminus of the ADP-ribosylated 38 kDa protein were determined by sequential analysis. The sequence was completely identical to that of glyceraldehyde-3-phosphate dehydrogenase. These results indicate that the endogenous mono-ADP-ribosylation which increased in the kindled group and decreased by the antiepileptics might be a specific reaction associated with the mechanisms of epileptogenesis.