Metabolic Syndrome in the Rat: Females are Protected Against the Pro-Oxidant Effect of a High Sucrose Diet

Abstract

Metabolic syndrome is more prevalent in men than in women. In an experimental dietary model of metabolic syndrome, the high-fructose–fed rat, oxidative stress has been observed in males. Given that estradiol has been documented to exert an antioxidant effect, we investigated whether female rats were better protected than males against the adverse effects of a high-sucrose diet, and we studied the influence of hormonal status in female rats. Males and females were first fed a sucrose-based or starch-based diet for 2 weeks. In the males, the plasma triglyceride (TG)-raising effect of sucrose was accompanied by significantly lowered plasma α-tocopherol and a significantly lowered α-tocopherol/TG ratio (30%), suggesting that vitamin E depletion may predispose lipoproteins to subsequent oxidative stress. In males, after exposure of heart tissue homogenate to iron-induced lipid peroxidation, thiobarbituric reactive substances were significantly higher in the sucrose-fed than in the starch-fed rats. In contrast, in sucrose-fed females, neither a decrease in vitamin E/TG ratio nor an increased susceptibility of heart tissue to peroxidation was observed, despite both a significantly decreased heart superoxide dismutase activity (14%) and a significant 3-fold increase in plasma nitric oxide concentration compared with starch-fed females. The influence of hormonal status in female rats was then assessed using intact, ovariectomized, or estradlol-supplemented ovariectomized female rats fed the sucrose or starch diet for 2 weeks. After exposure of heart tissue to iron-induced lipid peroxidation, higher susceptibility to peroxidation was found only in ovariectomized females fed the sucrose diet compared with the starch group and not in intact females or ovariectomized females supplemented with estradiol. Thus, estrogens, by their effects on antioxidant capacity, might explain the sexual difference in the pro-oxidant effect of sucrose diet resulting in metabolic syndrome in rats.

Metabolic syndrome susceptibility of suckling male and female rats given oral administration of natural honey compared with cane syrup

“…However, there was no gender differences in our neonatal rats fed with cane syrup. This plausibly confirmed that the resistance to MetS by the female rats reported by these workers [28] is associated with age and the hormonal factor responsible manifest at adult age of the rodent's life [29]. 3.96±0.20 3.74±0.34 * value highly significant (p < 0.0001) across the column; No significant difference (p ≥ 0.05) in the other circulating metabolic substrates amongst the control and treatment groups after 10-day treatment.…”

“…Male rats are not known to be resistant to abdominal obesity, hyperglycaemia, dyslipidaemia and other risk factors of renal and metabolic diseases. As documented by some researchers [7], adult female rodents are less susceptible to the adverse effects of sucrose consumption [28]. However, there was no gender differences in our neonatal rats fed with cane syrup.…”

Fructose-mediated stress signaling in the liver: implications for hepatic insulin resistance

“…Increases in the fructose load to the liver, through diets enriched with sucrose or fructose or via portal vein fructose infusion, can alter the bnormalQ postprandial intrahepatic milieu [12,[59][60][61][62][63][64]. We propose that these changes serve as signals of nutrient excess and elicit rapid responses that ultimately influence hepatic gene expression and insulin action.…”

Modulation of aortic vascular reactivity by sex hormones in a male rat model of metabolic syndrome

“…Alternatively, female rats appear to have a protection against diet-induced pathological alterations, such as hypertension and oxidative stress (Roberts et al, 2001;Busserolles et al, 2002).…”