Mechanisms underlying Li+ effects in glutamatergic and GABAergic neurotransmissions in the adult rat brain and in primary cultures of neural cells as revealed by 13C NMR.

We investigated by (13)C nuclear magnetic resonance (NMR) the mechanisms underlying Li(+) effects on glutamatergic and GABAergic neurotransmission systems in the adult rat brain and in primary cultures of cortical neurons and astrocytes during the metabolism of (1-(13)C) glucose or (2-(13)C) acetate. Adult male rats receiving a single dose of Li(+) intraperitoneally (7 mmol/kg) were infused 2 hr later, for 60 min, with (1-(13)C) glucose (80 mumol/min/kg) or (2-(13)C) acetate (240 micromol/min/kg). High-resolution (13)C NMR spectra of brain extracts prepared after the infusion revealed that Li(+) significantly decreased the incorporation of (13)C in glutamate and GABA (gamma-aminobutyric acid) carbons from (1-(13)C) glucose, but not from (2-(13)C) acetate.