Symmetrical distribution of amino acid neurotransmitters in the right and left cerebral cortex of the rat.

The level and activity of seven amino acids were examined in both the right and left areas of the cerebral cortex of the rat in order to determine their respective symmetrical distribution. In the first experiment, alanine, glycine, threonine, serine, GABA, aspartate, and glutamate were measured in six different regions of the cortex: medial, sulcal, and dorsal prefrontal as well as parietal, temporal, and occipital. The differences in the level of these amino acids in symmetrical regions of either side of the cortex were not statistically significant. In the second experiment, the in vivo synthesis from the [14C]glucose precursor of three amino acids, glutamate, glutamine, and GABA was measured using the cortical push-pull perfusion technique in the freely moving rat. Although differences in synthesis were found between the prefrontal and parietal areas of the cortex, no changes occurred between right and left hemispheres. These results indicate that for the resting levels of the amino acids examined in this study, no differential asymmetric distribution exists between right or left cortical regions of the rat's brain.