The stimulation of cerebral N2-methyl- and N22-dimethyl guanine-specific tRNA methyltransferases by methionine sulfoximine: An study

Abstract

The administration of a single convulsant dose or of multiple subconvulsant doses of L-methionine-dl-sulfoximine (MSO) to 18-day old rats results in a significant elevation of the specific activity of cerebral tRNA methyltransferases, as determined in an assay, using heterologous or species-homologous tRNAs as substrates. The increase was detectable as early as 90 min after MSO and persisted throughout the entire 5-6 h preconvulsant period. The 14[C]-methyl tRNA was purified, and hydrolyzed to its constituent bases and their distribution was quantitated by high performance liquid chromatography. A marked increase in the formation of 14[C]-N2-methyl- and 14[C]-N22-dimethyl guanine was noted in the MSO-treated animals, demonstrating a specific stimulation by MSO of the cerebral N2-methyl and/or N22-dimethyl guanine-specific tRNA methyltransferases.