Glucose homeostasis in thyroxine-treated BHE/cdb rats fed corn oil or hydrogenated coconut oil

Abstract

Glucose turnover was assessed in BHE rats fed either a 6% corn or hydrogenated coconut oil diet and treated with 10 μg thyroxine (T 4/100 g body weight/day or untreated. Regardless of fat souce, measures of fractional irreversible glucose turnover and Cori cycle activity were higher in T 4-treated rats than in control rats. T 4 also increased the alanine to glucose conversion. Treatment with T 4 resulted in less muscle and hepatic glycogen. Lipogenesis was greatly increased in the rats fed hydrogenated coconut oil and this effect was potentiated by T 4 treatment. Blood glucose levels were also lower in this group, suggesting that this blood glucose lowering was due to a combination of treatment effects on glycogenolysis and lipogenesis. It would appear that the main effect of T 4 was to alter the sources of glucose in the total glucose pool in the body, and that the differences in glucose oxidation, synthesis, and recycling were a reflection of the body's adaptation to this reduction.