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Department of Neurology, Cornell University Medical College, Burke Rehabilitation Center, 785 Mamaroneck Avenue, White Plains, NY 10605
Although thiamin deficiency is associated with impaired acetylcholine metabolism, the functional significance of the cholinergic lesion is controversial. Therefore, we tested the effect of cholinergic drugs on abnormal open-field behaviors in rats that were treated with a thiamin-deficient diet and thiamin antagonists. After only 1 day of treatment, staring increased significantly in rats given pyrithiamin, a centrally acting thiamine antagonist, but not in rats given oxythiamin, which acts only peripherally. Sniffing, resting and grooming were not altered by either treatment. The acetylcholinesterase inhibitor physostigmine was as effective as thiamin in decreasing staring in pyrithiamin-treated rats, but its peripherally acting analogue neostigmine had no effect. The central muscarinic blocker, atropine, blocked the effect of physostigmine. Methatropine, which acts only peripherally, did not. Arecoline, a direct muscarinic agonist, was as effective as physostigmine in decreasing staring. Nicotine had no effect, and the nicotinic ganglionic blocker mecamylamine did not block the effect of physostigmine. Increased staring behavior in pyrithiamin-treated rats appears to reflect an early central cholinergic muscarinic deficit.
KEY WORDS: thiamin deficiency open-field behavior acetylcholine pyrithiamin
1 This work was supported by National Institutes of Health grant NS15125. the Winifred Masterson Burke Relief Foundation, the Will Rogers Institute and the Brown and Williamson Tobacco Company.
Manuscript received 8 March 1982.