Effect of lithium on phosphoinositide metabolism in human brain: a proton decoupled (31)P magnetic resonance spectroscopy study.

BACKGROUND: The objective of our study was to evaluate whether lithium increases brain phosphomonoester (PME) levels in human subjects. METHODS: Proton decoupled (31)P magnetic resonance spectra were obtained from eight healthy volunteers before and after the administration of lithium carbonate, 450 mg b.i.d., for 7 and 14 days. RESULTS: Pairwise comparisons of the mole percent PME revealed a significant increase from baseline at day 7 and day 14 of lithium administration. CONCLUSIONS: An increase in PME concentration with 7 and 14 days of lithium administration in the human brain in vivo was observed. Because the inositol-1-monophosphate contributes to the PME peak, this result suggests that some of the initial actions of lithium may occur through a reduction of myo-inositol, which in turn may initiate a cascade of secondary changes at different levels of signal transduction process and gene expression in brain, effects that are ultimately responsible for the therapeutic benefits of lithium.