Metabolic Effects of Troglitazone on Fructose-Induced Insulin Resistance in the Rat

Abstract

Troglitazone is a new orally active hypoglycemic agent that has been shown to reduce insulin resistance and hyperinsulinemia in both diabetic animal models and non-insulin-dependent diabetes mellitus (NIDDM) subjects. To determine whether this drug could prevent the development of fructose-induced insulin resistance and related abnormalities, we studied the effects of troglitazone on the insulin resistance induced by fructose feeding in rats. Normal male Sprague-Dawley rats were fed a high-fructose diet for 3 weeks with and without troglitazone as a food admixture (0.2%) or were fed normal chow to serve as a control group. In vivo insulin resistnace was measured by the euglycemic hyperinsulinemic clamp technique at two different insulin infusion rates, 29 (submaximal stimulation) and 290 (maximal stimulation) pmol.kg-1.min-1. Fructose feeding markedly reduced submaximal glucose disposal rate (GDR) (113.8 +/- 8.3 vs. 176.0 +/- 5.6 mumol.kg-1.min-1, P < 0.05) and maximal GDR (255.9 +/- 5.6 vs. 313.6 +/- 10.5 mumol.kg-1.min-1, P < 0.05), reduced the suppressibility of submaximal hepatic glucose production (HGP; 45.5 +/- 5.0 vs. 11.7 +/- 5.0 mumol.kg-1.min-1, P < 0.05), and resulted in hypertriglyceridemia and hypertension. Troglitazone treatment completely restored the GDR (submaximal 158.2 +/- 5.6, maximal 305.3 +/- 6.1 mumol.kg-1.min-1) and submaximal HGP (9.4 +/- 2.8 mumol.kg-1.min-1) to control levels and also normalized the elevated plasma triglyceride concentration and systolic blood pressure levels in fructose-fed rats.(ABSTRACT TRUNCATED AT 250 WORDS)