Effects of short-term toluene exposure on ligand binding to muscarinic acetylcholine receptors in the rat frontal cortex and hippocampus.
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.
Tsuga
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Division of Health Effects Research, National Institute of Industrial Health, Kawasaki, Kanagawa 214-8585, Japan.
Honma
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D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D002217:Carbachol / Q000378:metabolism / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005625:Frontal Lobe / Q000187:drug effects / Q000378:metabolism*; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D019570:Inhalation Exposure; D008297:Male; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D019832:N-Methylscopolamine / Q000378:metabolism; D011869:Radioligand Assay; D051381:Rats; D011916:Rats, Inbred F344; D011976:Receptors, Muscarinic / Q000378:metabolism*; D013997:Time Factors; D014050:Toluene / Q000633:toxicity*; D014316:Tritium
D011976:Receptors, Muscarinic; D014316:Tritium; D014050:Toluene; D002217:Carbachol; D019832:N-Methylscopolamine