Consumption of carbohydrate solutions enhances energy intake without increased body weight and impaired insulin action in rat skeletal muscles

Abstract

In the present study, we investigated whether replacement of tap water by fructose or sucrose solutions affect rat body weight and insulin action in skeletal muscles. Rats were fed standard rodent chow ad libitum with water, or water containing fructose (10.5% or 35%) or sucrose (10.5% or 35%) for 11 weeks. Body weight and energy intake from chow and drinking solutions were measured. Urinary catecholamines secretion was determined after 50-60 days. At the end of the feeding period, soleus and epitrochlearis were removed for in vitro measurements of glucose uptake (with tracer amount of 2-[3H]-deoxy-D-glucose) and PKB Ser473 phosphorylation (assessed by Western Blot) with or without insulin. Fructose and sucrose solutions enhanced daily energy intake by about 15% without increasing rat body weight. Secretion of urinary noradrenaline was higher in rats drinking a 35% sucrose solution than in rats drinking water. In the other groups, urinary noradrenaline secretion was similar to rats consuming water. Urinary adrenaline secretion was similar in all groups. Insulin-stimulated glucose uptake and insulin-stimulated PKB phosphorylation were not reduced by intake of fructose or sucrose solution. Fructose and sucrose solutions enhanced energy intake but did not increase body weight. Although noradrenaline may regulate body weight in rats drinking 35% sucrose solution, body weight seems to be regulated by other mechanisms. Intake of fructose or sucrose solution did not impair insulin-stimulated glucose uptake or signaling in skeletal muscles.