Tsuga_2000_Neurotoxicol.Teratol_22_603

Changes in the binding affinity of the muscarinic acetylcholine receptor agonist carbamylcholine were determined in membranes isolated from the brains of rats exposed to toluene at concentrations of 500-2,000 ppm for 6 h. Membrane fractions of the frontal cortex and hippocampus were prepared and agonist-binding affinities were determined by measuring the displacement of [3H]N-methyl scopolamine-binding activity by carbamylcholine. In the frontal cortex, the affinity of high-affinity carbamylcholine binding was reduced following exposure to toluene at a concentration of 1000 ppm or higher. However, in the hippocampus, the affinity of high-affinity binding of carbamylcholine was increased following exposure to toluene. These observations suggest that toluene exposure affects binding affinity of carbamylcholine, and the effect differs by brain region.