Dietary lipoic acid supplementation prevents fructose-induced hypertension in rats

Abstract

Background and aims: In fructose-induced hypertension in Wistar-Kyoto (WKY) rats, excess endogenous aldehydes bind sulfhydryl groups of membrane proteins, alter membrane Ca2+ channels and increase cytosolic free calcium and blood pressure. The thiol compound N-acetyl cysteine prevents such hypertension by binding these aldehydes and normalizing membrane Ca2+ channels and cytosolic free calcium. The aim of this work was to investigate whether dietary supplementation of an endogenous fatty acid, alpha-lipoic acid, another thiol compound known to increase cysteine and glutathione, prevents this hypertension and its associated biochemical and histopathological changes.

Methods and results: Starting at seven weeks of age, animals were divided into three groups of six animals each and treated as follows: control (normal diet and normal drinking water); fructose (normal diet and 4% fructose in drinking water); fructose + lipoic acid (diet supplemented with lipoic acid 500 mg/kg feed and 4% fructose in drinking water). After 14 weeks, systolic blood pressure, platelet [Ca2+]i, plasma glucose and insulin and kidney and aortic aldehyde conjugates were significantly higher in the fructose group. These also displayed smooth muscle cell hyperplasia in the small arteries and arterioles of the kidneys.

Conclusion: Dietary alpha-lipoic acid supplementation in fructose-treated WKY rats may prevent their increase in systolic blood pressure by normalizing cytosolic [Ca2+], blood glucose and insulin, kidney and aortic aldehyde conjugates and preventing adverse renal vascular changes.