Demonstration of a Specific Metabolic Effect of Dietary Disaccharides in the Rat

Abstract

Male Wistar rats were starved and refed diets containing either 40% carbohydrate as monosaccharides (glucose, fructose, invert sugar) or disaccharides (maltose, sucrose), or 42.2% carbohydrate as glucose. Induction of various liver enzymes and changes in total liver lipid levels by the different dietary sugars were studied. Liver enzymes measured included glucose-6-phosphate dehydrogenase (g6pd), 6-phosphogluconate dehydrogenase (6PGD), malic enzyme (ME), phosphofructokinase (PFK), L-alpha-glycerol phosphate dehydrogenase (LalphaGPD), pyruvate kinase (PK), citrate cleavage enzyme (CCE), acetyl CoA carboxylase (AcCoAC), and fatty acid synthetase (FAS). The responses in enzyme activity to diets containing glucose or invert sugar were used as the basal response. Enzyme responses to refeeding the carbohydrate diets fell into three categories: (1) enzyme activity increased both by the disaccharide configuration of the carbohydrate and by fructose (G6PD, PK, CCE, AcCoAC, FAS); (2) enzyme activity increased only by the disaccharide configuration of the carbohydrate (6PGD, ME); and (3) enzyme activity increased only by fructose (PFK, LalphaGPD). Total liver lipid level was increased both by the disaccharide configuration of the carbohydrate and by fructose. Refeeding diets containing equal molar amounts of glucose or maltose did not abolish the disaccharide effect. The data indicate that the disaccharide configuration of maltose and sucrose may have an effect at the gastrointestinal level, which causes an increased induction of certain enzymes in the liver.

Effects of Different Dietary Carbohydrates on Hepatic Enzymes of Copper-Deficient Rats

“…This is in agreement with other studies that follow long-term feeding of fructose containing sugars (22)(23)(24)(25). In agreement with Cohen et al (22) the activity of PEPCK was unaffected by the type of dietary carbohydrate.…”

Metabolic and behavioural effects of sucrose and fructose/glucose drinks in the rat

“…Studies that have examined the acute effects of equal intake of sucrose or fructose/glucose solution have shown that the insulinogenic index ( P I= P G, 0-180 min) is higher for sucrose than for fructose/glucose [40,41]. Others have reported that acute ingestion of sucrose more effectively elevates hepatic enzymes involved in de novo lipogenesis than free fructose/glucose, including glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, acetyl CoA carboxylase and malic enzyme [42,43]. It follows that ingestion of free fructose/glucose may lead to a greater accumulation or prolonged exposure of hepatocytes to metabolic intermediates of fructose metabolism, which promote inflammation or oxidative stress.…”

Comparative effects of some carbohydrates on serum sugars, triglycerides and digestive hydrolases

“…Howard and Yudkin (1963) and Bucko et al (1969) found that fructose and saccharose were less efficient in that respect than glucose and starch, while Deschodt-Lanckman et al (1971) reported that starch, glucose and saccharose had the same effect, and that only fructose was less stimulatory. It has also been reported that equimolar mixtures of glucose and fructose give different results than those obtained with sucrose (Howard and Yudkin, 1963 ;Thompson et al, 1979 ;Michaelis et al, 1975). Aside Sarda and Desnuelle (1959) at pH 9.0 using a triolein substrate stabilized with gum arabic (triolein 45 ml, 10 p. 100 gum arabic 360 ml).…”