Diurnal Changes in the Concentrations of Plasma Lipids, Sugars, Insulin and Corticosterone in Rats fed Diets Containing Various Carbohydrates

Abstract

Rats were fed diets with sucrose or starch as the carbohydrate source and in another experiment with glucose and fructose. After 30 days, groups of 5 rats were killed at 2 h intervals over a period of 24 hours. Plasma triglyceride concentrations were higher in sucrose-fed rats than in those fed starch, and in fructose-fed rats than in those fed glucose. This was also true of free fatty acid concentrations. Visible lipemia was observed in some rats fed a diet with sucrose or fructose. There was little difference in plasma glucose concentrations between the groups, but sucrose or fructose feeding increased fructose concentrations. The differences between plasma insulin concentrations of rats fed fructose and glucose was less than those previously seen. The corticosterone concentrations were also not greatly different. A diurnal rhythm was observed in the concentrations of plasma triglyceride, free fatty acid, corticosterone and to a lesser extent insulin. The implications of these results are discussed in relation to the hyperlipidemic effect of sucrose.