Effects of chronic modification of dietary fat and carbohydrate on the insulin, corticosterone and metabolic responses of rats fed acutely with glucose, fructose or ethanol.

1. Male rats were fed for 14 days on powdered diets containing (by weight) 53% of starch, or on diets in which 20g of starch per 100g of diet was replaced by lard or corn oil. They were then fed acutely by stomach tube with a single dose of glucose, fructose or ethanol of equivalent energy contents, or with 0.15m-NaCl. The serum concentrations of corticosterone, insulin, glucose, glycerol, triacylglycerol and cholesterol were measured up to 6h after this treatment. 2. Feeding saline (0.9% NaCl) acutely to the rats maintained on the three powdered diets produced a small transient increase in circulating corticosterone that was similar to that in rats maintained on the normal 41B pelleted diet. 3. Feeding glucose acutely to the rats on the powdered diets produced peak concentrations of corticosterone that were 2-3-fold higher than those seen in rats maintained on the 41B diet. The duration of this response increased in the order starch diet