The effect of diazepam on brain levels of S-adenosyl-L-methionine and S-adenosyl-L-homocysteine: possible correlation with protection from methionine sulfoximine seizures.

Administration of the long latency convulsant, L-methionine-d,1-sulfoximine (MSO) results in an increase in brain methylation flux. We determined the effects of the anticonvulsant, diazepam (DZ) on MSO seizures and on brain levels of S-adenosyl-L-methionine (AdoMet) and S-adenosyl-L-homocysteine (AdoHcy) to indicate possible alterations in the brain methylation pathway. We report a dose related inhibition of MSO seizures by DZ. In addition, DZ significantly increased brain levels of AdoMet and AdoHcy and reversed the MSO-induced decreases in AdoMet and AdoHcy. DZ also blocked the MSO induced increase in the methylation index (AdoMet/AdoHcy). The data indicates an inhibition of MSO induced increases in brain methylation by DZ. Possible mechanisms for the effect of DZ on the cerebral methylation pathway are discussed.