Impairment of acetylcholine synthesis in thiamine deficient rats developed by prolonged tea consumption.

The synthesis of whole brain acetylcholine is reduced in thiamine deficient rats produced by prolonged administration of tea. In those rats fed a normal diet and given tea (1:50, w/v) instead of drinking water for 20 weeks, the conversion of [14C] pyruvate to [14C]acetylcholine decreased by 35%. However, no neurological symptoms were observed. Administration of tea to rats fed a thiamine half-deficient diet for 7-8 weeks caused not only 60% decrease in acetylcholine synthesis but also neurological symptoms. This decreased synthesis of acetylcholine is related to a decline in pyruvate dehydrogenase activity. The results suggest that prolonged administration of tea to rats cause an impairment of acetyl CoA production resulting in a deficit in acetylcholine synthesizing capacity.