Regional levels of GABA and glutamate in mouse brain following exposure to pain

Based on previous studies from this laboratory, a study of the effects of pain on regional brain levels of GABA and glutamate were performed using male CFl mice. Gas-chromatographic analysis revealed no significant differences in these substrates in “subcortical” areas. In the “cortical” areas, pain produced a significant elevation of GABA levels and a small, but significant, decrease in glutamate levels. Neither of these changes was observed in animals pretreated with morphine before exposure to pain. Restraint stress failed to produce the same changes. The ratio of GABA to glutamate was a reliable index of exposure to pain.