Changes in lipid metabolism and antioxidant defense status in spontaneously hypertensive rats and Wistar rats fed a diet enriched with fructose and saturated fatty acids.

Larger doses of fructose and saturated fat have been associated with oxidative stress and development of hypertension. The effects of modest amounts of fructose and saturated fatty acids on oxidative stress are unknown. To increase knowledge on this question, 10-wk-old spontaneously hypertensive rats and Wistar rats were fed for 8 wk with a control diet or an experimental diet enriched with fructose (18%) and saturated fatty acids (11%; FS diet). The total antioxidant status of organs and red blood cells was assayed by monitoring the rate of free radical-induced red blood cell hemolysis. Sensitivity of very low-density lipoprotein and low-density lipoprotein (VLDL-LDL) to copper-induced lipid peroxidation was determined as the production of thiobarbituric acid-reactive substances. Antioxidant enzymes and vitamins were also measured to establish the oxidative stress effect. The FS diet did not affect blood pressure in either strain, but it increased plasma insulin concentrations only in Wistar rats without affecting those of glucose of either strain. The FS diet significantly enhanced plasma and VLDL-LDL triacylglycerol concentrations without affecting concentrations of VLDL-LDL thiobarbituric acid-reactive substances. The decreased content of arachidonic acid and total polyunsaturated fatty acids in VLDL-LDL by the FS diet may have prevented lipid peroxidation in this fraction. Moreover, FS consumption by both strains was accompanied by a significant increase in total antioxidant capacity of adipose tissue, muscle, heart, and liver. This may have resulted from increased tissue ascorbic acid levels and glutathione peroxidase and glutathione reductase activities in tissues. These findings clearly indicate that the FS diet did not alter blood pressure of spontaneously hypertensive rats and Wistar rats. The FS diet resulted in hypertriglyceridemia but increased the total antioxidant status, which may prevent lipid peroxidation in these rats.

Girard A ，Madani S ，El Boustani ES ，Belleville J ，Prost J ... -  《NUTRITION》

Fructose-enriched diet modifies antioxidant status and lipid metabolism in spontaneously hypertensive rats.

Girard A ，Madani S ，Boukortt F ，Cherkaoui-Malki M ，Belleville J ，Prost J ... -  《NUTRITION》

Influence of alpha-lipoic acid on lipid peroxidation and antioxidant defence system in blood of insulin-resistant rats.

High fructose feeding induces insulin resistance and hyperinsulinaemia in rats. A role for oxidative stress in the occurrence of insulin resistance has been suggested by several workers. The aim of this study was to investigate the effect of alpha-lipoic acid (LA) on oxidant-antioxidant balance in rats fed on a high-fructose diet that showed characteristic features of insulin resistance. Male Wistar rats weighing 150-170 g were divided into seven groups. The control group received the control diet containing starch. The fructose group was given a high-fructose diet (>60% of total calories). The third and fourth groups were given fructose diet and were administered two different doses of LA at a low dose (35 mg/kg body weight) and high dose (70 mg/kg body weight) using olive oil as vehicle. The fifth group received fructose diet and olive oil. The sixth group received control diet and was administered LA (70 mg/kg body weight). And, the seventh group received the control diet and olive oil. Products of lipid peroxidation and activities of enzymic antioxidants, namely superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase and glutathione reductase, in red blood cells were assayed. Levels of non-enzymic antioxidants alpha-tocopherol, ascorbic acid and reduced glutathione were determined in plasma. The levels of lipid peroxides, diene conjugates and thiobarbituric acid-reactive substances were significantly higher in fructose-fed rats. Inadequate antioxidant system was observed in high-fructose-fed rats. Treatment of fructose rats mitigated the imbalance between peroxidation and antioxidant defence system at both the doses tested. Increases in glucose, triglycerides, free fatty acids, insulin and insulin resistance were observed in fructose-fed rats. LA administration prevented these alterations and improved insulin sensitivity. Significant positive correlations were obtained between insulin resistance and lipid peroxidation indices. Increased lipid peroxidation and deficient antioxidant system are observed in high-fructose-fed rats. LA administration preserves the antioxidant system and lowers lipid peroxidation. The findings suggest an interrelationship between lipid peroxidation and insulin resistance.

Thirunavukkarasu V ，Anuradha CV 《DIABETES OBESITY & METABOLISM》

Globularia alypum aqueous extract decreases hypertriglyceridemia and ameliorates oxidative status of the muscle, kidney, and heart in rats fed a high-fructose diet.

Fructose is widely used as a food ingredient and has potential to increase oxidative stress. Moreover, the beneficial health effects of plant polyphenols are frequently attributed to their potent antioxidant effects. We hypothesized that administration of Globularia alypum (Ga) aqueous extract would reduce metabolic disorders and oxidative stress induced in rats fed a high-fructose diet. Male Wistar rats (n = 24) weighing 242 ± 13 g were divided into 4 groups and fed, during 14 week, diets containing 20% casein and 61% cornstarch (control diet, or C) or fructose (F), and Ga supplementation (0.5%; CGa and FGa). Compared with control group, rats fed a high-fructose diet increased plasma triglycerides (TG; +48%) and very low-density lipoprotein-TG (+45%) levels. In addition, thiobarbituric acid reactive substances were increased in the liver (+31%), heart (+55%), and muscle (+58%). Moreover, activities of superoxide dismutase in the liver and heart, catalase in liver and glutathione peroxidase in the heart were diminished. In the FGa group, a hypertriglyceridemic effect was observed concomitantly with a low level of TG in very low-density lipoprotein and high-density lipoprotein 2, compared with the F group. Thiobarbituric acid reactive substance concentrations were reduced in the kidney (-42%)and muscle (-76%), and antioxidant enzymes activity was increased for superoxide dismutase in the muscle (+81%) and heart (+28%), and for glutathione peroxidase, in the kidney (+70%) and heart (+30%). In conclusion, the Ga extract has a beneficial effect on plasma TG and gives a promising perspective for hypertriglyceridemia treatment. Moreover, in the muscle and kidney, Ga is effective by lowering lipid peroxidation and improves antioxidant enzymes.

Taleb-Dida N ，Krouf D ，Bouchenak M 《-》

Abdominal adipose tissue: early metabolic dysfunction associated to insulin resistance and oxidative stress induced by an unbalanced diet.

Rebolledo OR ，Marra CA ，Raschia A ，Rodriguez S ，Gagliardino JJ ... -  《HORMONE AND METABOLIC RESEARCH》