An Aberration of Glucose Metabolism and Steroidogenesis in Adrenals of Thiamin-Deficient Rats1

Rats were fed a thiamin-deficient(TD) casein-sucrose diet for 32-35 days and controls were pair-fed the same diet with thiamin added. When compared to the pair-fed controls, TD rats had significantly lower rises in plasma corticosterone in response to ether vapor and to ACTH injection. The half-time of iv injected radioactive corticosterone was similar in both groups. Quartered adrenals from TD rats produced significantly less corticosterone in response to ACTH added to the incubation media than adrenals from pair-fed controls. Severe thiamin deficiency was confirmed by the markedly decreased in vitro transketolase activity observed in adrenal and red blood cell (RBC) and by the low activity of pyruvate decarboxylase observed in adrenals. A marked in vitro thiamin pyrophosphate effect was observed only in the activities of RBC transketolase and adrenal pyruvate decarboxylase of TD rats. The effect was trivial in RBC's and adrenals from pair-fed controls. ACTH produced negligible stimulation of 1-14C- and 6-14C-glucose oxidation in quartered adrenals from thiamindeficient animals, whereas a significant increase was observed in pair-fed controls. The activity of hexose monophosphate pathway dehydrogenase and of cytosol malic enzyme was not significantly affected by thiamin deficiency as compared to pair-fed controls. It is concluded that adrenal glucose catabolism and steroidogenesis in response to ACTH are impaired in thiamin deficiency. This effect of thiamin deficiency on adrenal glucose catabolism may result in diminished NADPH and cyclic AMP formation and thereby interfere with the steroidogenic action of ACTH. (Endocrinology91: 1206, 1972)