L-methionine decreases dendritic spine density in mouse frontal cortex.

Schizophrenia postmortem brain is characterized by gamma aminobutyric acid downregulation and by decreased dendritic spine density in frontal cortex. Protracted L-methionine treatment exacerbates schizophrenia symptoms, and our earlier work (Tremolizzo et al. and Dong et al.) has shown that L-methionine decreases reelin and GAD67 transcription in mice which is prevented by co-administration of valproate. In this study, we observed a decrease in spine density following L-methionine treatment, which was prevented by co-administration of valproate. Together with our earlier findings conducted under the same experimental conditions, we suggest that downregulation of spine density in L-methionine-treated mice may be because of the decreased expression of reelin and that valproate may prevent spine downregulation by inhibiting the methylation induced decrease in reelin.