In vitro1H NMR spectroscopy shows an increase in N-acetylaspartylglutamate and glutamine content in the hippocampus of amygdaloid-kindled rats: NAAG and glutamine in the kindled rat

We examined energy metabolism and amino acid content in the hippocampus of amygdaloid-kindled rats using H-1 NMR spectroscopy. Three weeks after the last stage 5 seizure, kindled rats were killed by microwave irradiation. The hippocampus was dissected out and subjected to MeOH/CHCl3 extraction. All H-1 spectra were analyzed to quantify absolute concentrations using a non-linear least squares method, combined with a prior knowledge of chemical shifts. Saturation effects were compensated for by the T1 measurement of each component. Levels of energy metabolism-related compounds, phosphocreatine, creatine, glucose and succinate were the same in both kindled rats and sham controls. Lactate concentration had a tendency to increase, although this was not statistically significant. When compared with sham controls, levels of aspartate, glutamate, glycine and glutamine, as well as GABA and inositol, were increased in the ipsilateral but not the contralateral hippocampus. In contrast, levels of taurine, alanine and threonine were unchanged. Finally, N-acetylaspartylglutamate content was elevated, whereas N-acetyl-L-aspartate content was unaltered in the ipsilateral hippocampus of kindled animals. Our results suggest that amygdala kindling may affects amino acid metabolism, but not energy metabolism.