Chronic myo-inositol increases rat brain phosphatidylethanolamine plasmalogen

Background: Oral myo-inositol (12-18 g/day) has shown beneficial effect in placebo-controlled studies of major depression, panic disorder, and obsessi ve compulsive disorder, and preliminary data suggest it also map be effecti ve in bipolar depression. Evidence linking antidepressant activity to membr ane phospholipid alterations suggested the examination of acute and chronic myoinositol effects on rat brain membrane phospholipid metabolism. Methods: With both P-31 nuclear magnetic resonance (NMR) and quantitative h igh-performance thin-layer chromatography (HPTLC; hydrolysis) methods, rat brain phospholipid levels were measured after acute (n = 20, each group) an d chronic myo-inositol administration (n = 10, each group), With P-31 NMR, we measured myoinositol rat brain levels after acute and chronic myoinosito l administration. Results: Brain myo-inositol increased by 17% after acute myo-inositol admin istration and by 5% after chronic administration, as compared with the cont rol groups. Chronic myo-inositol administration increased brain phosphatidy lethanolamine (PtdEtn) plasmalogen by 10% and decreased brain PtdEtn by 5%, thus increasing the ratio PtdEtn plasmalogen (PtdEtn-Plas)/PtdEtn by 15%. Phosphatidylethanolamine plasmalogen levels quantified by P-31 NMR and HPTL C were highly correlated. The validity and reliability of the P-31 NMR meth od for phospholipid analysis were demonstrated with phospholipid standards. Conclusions: The observed alteration in the PtdEtn-Plas/PtdEtn ratio could provide insights into the therapeutic effect of myo-inositol in affective d isorders. Biol Psychiatry 2001;49:444-453 (C) 2001 Society of Biological Ps ychiatry.