Carbohydrate and lipid metabolism in male and female rats

Abstract

It has been suggested that there is a correlation between plasma triacylglycerol levels, carbohydrate consumption and the incidence of atherosclerosis in man. Fasting triacylglycerol levels have been reported to be related to carbohydrate intake in rats and the nature of the carbohydrate can also affect the levels of the lipid. Dietary sucrose is more hypertriglyceridemic than equicaloric glucose diets. Serum triacylglycerol levels have been also reported to be higher in males than in females, a difference which is maintained on various carbohydrate enriched diets. In this study male and female rats have been used as experimental models to examine the effects of prolonged ingestion of sucrose and glucose, in addition to the normal CDD [R] diet, on some key lipogenic enzymes. Hepatic acetyl CoA carboxylase, fatty acid synthetase, glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and fructose 1,6-bisphosphate aldolase activities were higher in adult females than in males of a comparable age. No sex related difference in the levels of microsomal glycerolphosphate acyltransferase was observed.A comparison of the animals fed on sucrose and glucose supplemented diets shows that the disaccharide increases the activity of the enzymes examined to a greater extent than the monosaccharide with the exception of 6-phosphogluconate dehydrogenase which was lower in the sucrose-fed animals. These dietary effects appear to be common to both sexes and thus the sex differences in enzyme activities are maintained despite the changes in the diet. No sex-related differences in enzyme activities were observed in young rats fed on Dixon diet for 7 days after weaning but adult females had higher enzyme levels than male animals fed on the same diet. Possible differences in hormone levels in male and female rats may account for the sex-related differences observed in this study.