The present study was undertaken to measure the activities of several hepatic enzymes of regulatory importance in the pathways of lipogenesis and gluconeogenesis in rats fed diets marginally deficient in copper (1.2 micrograms Cu/g of diet) and containing either fructose, glucose, or starch as the carbohydrate sources. Although all copper-deficient rats exhibited the characteristic signs of copper deficiency, they were more pronounced in rats fed the diet containing fructose. Except for the activity of phosphoenolpyruvate carboxykinase which was unaffected either by copper deficiency or by the type of dietary carbohydrate, the hepatic activities of glucose-6-phosphate dehydrogenase, malic enzyme, L-alpha-glycerophosphate dehydrogenase and fructose 1,6-diphosphatase were unaffected by copper deficiency but were affected by the type of carbohydrate in the diet. Fructose produced the greatest increase in enzymatic activities, whereas starch produced the least activity and glucose induced an intermediate effect. These results indicate that the deleterious effects of a fructose diet deficient in copper on biochemical and physiological indices could not be due to an immediate metabolite of fructose. However, the involvement of a subsequent metabolite of fructose in the mechanism of copper utilization and/or requirement cannot be excluded.

Animals↗

PubMed1984

Effect of dietary sucrose on the SHR/N-corpulent rat: a new model for insulin-independent diabetes.

A new congenic strain of genetically obese rat, SHR/N-corpulent (cp), was studied. Young male corpulent (cp/cp) and lean (cp/+ or +/+) rats approximately 5 wk of age were fed a diet containing 54% carbohydrate as either sucrose or cooked cornstarch for 9 wk. A phenotype effect was observed with body weight, fasting levels of serum insulin, triglyceride and total cholesterol, levels of serum insulin and glucose after an oral glucose load, and level of urine glucose (corpulent greater than lean), and with systolic blood pressure (corpulent less than lean). Only lean rats were hypertensive. Corpulent rats were hyperinsulinemic, hyperlipidemic, exhibited glycosuria, and were hyperglycemic after an oral glucose load. Lean rats were hyperinsulinemic, but normoglycemic. A diet effect (sucrose greater than starch) was observed with body weight, level of serum glucose after an oral glucose load, and urine volume in both corpulent and lean rats, and with levels of serum insulin and total urine glucose in corpulent rats. Corpulent rats fed sucrose had 20 to 40% higher levels of serum glucose and insulin after an oral glucose load, and twice the amount of total urine glucose, than did corpulent rats fed starch. The data demonstrate that corpulent rats have metabolic characteristics associated with insulin-independent diabetes in humans and that sucrose is more diabetogenic than starch. Manifestation of hyperglycemia in this model may be the result of superimposing obesity on an insulin-resistant genetic background.

Animals↗

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