Significant Changes in the Amounts of Neurotransmitter and Related Substances in Rat Brain Induced by Subacute Exposure to Low Levels of Toluene and Xylene

Abstract

Rats were exposed to toluene and xylene at 200-800 ppm for 30 days. After exposure, changes in the dopamine, norepinephrine, serotonin, acetylcholine (ACh), cyclic AMP, cyclic GMP, GABA, glutamic acid, glutamine, aspartic acid, taurine, glycine and alanine content of different areas of the brain were investigated. ACh ih the striatum and whole brain were reduced dosedependently by toluene and xylene. The reduction at 800 ppm of the solvents was in the range of 10 to 20% of the ACh content of the control rats. Toluene and xylene caused different changes in monoamine content other than ACh, but the changes were not dose-dependent. Among the seven free amino acids that are the main amino acid components of the brain, the glutamine content was increased by toluene and xylene at 800 ppm. Decrease in ACh and increase in glutamine in the brain appear to be phenomena common to many kinds of organic solvents including toluene and xylene after acute and subacute exposure.