Effect of thiamine deprivation on thiamine metabolism in mice

Mice were made deficient by thiamin deprivation. Thiamin pyrophosphokinase and thiamin pyrophosphatase activities were measured, and their changes were compared to transketolase (TK), pyruvate and alpha-ketoglutarate dehydrogenase (DG) activities and thiamin pyrophosphate (TPP) level in the same tissues. Thiamin pyrophosphokinase activity was increased on day 10 of thiamin deficiency and remained unchanged within the next period of investigation. Thiamin pyrophosphatase activity decreased after 5 days and was enhanced in 10, 15 and 20 days of deficiency. This fact may be related to the regulatory role of the enzyme in the intertissue vitamin distribution and transport. The liver TPP level was the earliest and most specific indicator of the thiamin status as thiamin deficiency developed, and pyruvate DG was more drastically inhibited than alpha-ketoglutarate DG. Blood TK was more sensitive to thiamin deprivation than liver TK. In both cases we obtained a more (20-40% in blood) or less (5-10% in liver) pronounced TPP-stimulatory effect of transketolase activity.