Proton MRS was used to detect brain alcohol after repeated alcohol exposure in human subjects. MRS detectability measurements were made after administration of an alcoholic drink (0.6 g/kg alcohol) and after an identical drink administrated 6 h later. Between-drink differences in the methyl proton triplet resonance of ethyl alcohol were assessed at statistically equivalent and near-peak blood alcohol concentrations (reflecting brain alcohol concentrations) and statistically equivalent internal standard N-acetyl resonance areas after Drinks 1 and 2, respectively. Brain alcohol detectability was not altered in TE 30-ms spectra but was increased in all five subjects after Drink 2 by an average of 70% in TE 270-ms spectra (p < 0.01). This was accompanied by significant between-drink differences in subjective ratings of alcohol's effects, suggestive of induction of acute alcohol tolerance. These findings suggest increased brain alcohol detectability in TE 270-ms spectra after repeated alcohol exposure that may reflect acute alcohol tolerance.
Recent advances in the methodology of magnetic resonance spectroscopy now permit localized proton (1H) spectroscopy of the human brain in clinical magnetic resonance systems. In this study, localized 1H spectroscopy was used to observe directly the stimulation of brain metabolic activity in patients undergoing electroconvulsive therapy (ECT) and to compare results obtained before and after treatments. Persistent increases in lactate were expected on the basis of animal data but these increases were small and equivocal 1 hour after ECT. In contrast, a large increase in a lipid signal from before to after ECT was observed in 5 patients when short echo times were used. We postulate that a significant portion of this lipid signal is related to maximal activation of the phosphatidylinositol system (increased levels of diacylglycerol and free fatty acids) have generalized inhibitory effects potentially relevant to both the clinical pathophysiology of seizures and the efficacy of ECT in major affective disorders.
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