[Effect of polyphenols on vascular dilation in rats receiving a high-fat diet]

Consumption of a high-fat diet (HFD) leads to the development of metabolic syndrome (MS), and the use of polyphenols can have a protective effect, reducing the severity of MS and preventing disorders of the cardiovascular system. The aim of the study was to test the hypothesis of a possible protective effect of polyphenol (resveratrol and quercetin) usage on the reactivity of the mesenteric arteries in Wistar rats fed an excessive amount of fat in the diet.

The study included 4 groups of Wistar rats: the HFD group (n=15) received HFD (50% fat by calories), groups HFD+R (n=10) and HFD+Q (n=10) were fed HFD, and resveratrol and quercetin were administered intragastrically at a dose of 50 mg/kg body weight, respectively; rats of the control group (SD, n=15) received a standard diet. After 8 weeks, the reactions of the mesenteric arteries preconfigured with phenylephrine to acetylcholine (ACh) and sodium nitroprusside (NP), estimated as percentage of the contraction amplitude to phenylephrine, were studied in the absence and with the use of NO-synthase blockers (L-NAME). The diameter of the vessels was measured in the MMC program using in vivo microphotography and video recording.

Administration of polyphenols under HFD had a protective effect on the severity of MS: it prevented an increase in blood pressure, reduced dyslipidemia and visceral obesity, which are characteristic of HFD. Evaluation of the functional state of the mesenteric arteries (in vivo) showed that the use of resveratrol and quercetin prevented inhibition of the dilation of the mesenteric arteries to ACh: total vascular reactivity with a stepwise increase in the concentration of ACh (in the range of 10-10-10-5 М) in HFD+R and HFD+Q rats did not differ from the control, whereas in the HFD group it was 33.9% less than in the SD group. At the ACh concentration of 10-5 M, the amplitude of mesenteric artery vasodilation in the HFD rats was reduced and amounted to 85.0±5.2 vs 106.1±6.4% in control rats (р<0.001), and in the rats treated with polyphenols it did not differ from the control (103.9±8.6% for HFD+R, 99.8±6.3% for HFD +Q). Blockade of NO-synthase reduced the amplitude of dilation in HFD rats by 46.6%, while in the control group - by 68.7%, in HFD+R group - by 68.4%, in HFD+Q group - by 71.3%. Reactivity to NP did not differ between the groups.

The consumption of polyphenols (resveratrol and quercetin) with excessive fat intake reduces the severity of MS: loweres visceral obesity, improves carbohydrate and lipid metabolism, prevents blood pressure rise. Data have been obtained confirming the hypothesis of the protective effect of polyphenols in HFD on the functional state of the mesenteric arteries of rats: resveratrol or quercetin intake prevents the development of endothelial dysfunction characteristic of HFD, preserving NO-dependent vasodilation mechanisms.