Changes in acetylcholine metabolism in rat brain after a short-term exposure to toluene and n-hexane

To clarify the effects of organic solvents on the central nervous system (CNS), we exposed rats to toluene or n-hexane gas or a mixture of the two compounds at 1000-8000 ppm for 8 h, and measured acetylcholine (ACh) content, choline acetyltransferase (ChAT) and acetylcholine esterase (AChE) activities in homogenized rat hippocampus. ACh was increased at low concentrations of the solvents, but was markedly reduced at high concentrations. ChAT activity was significantly reduced at high concentrations of solvent mixtures. AChE activity was increased by solvents. We concluded that both the decrease in ChAT activity and the increase in AChE activity were the cause of the decrease in ACh content.