Prevention of hypercholesterolemia and atherosclerosis in the hyperlipidemia- and atherosclerosis-prone Japanese (LAP) quail by taurine supplementation

Abstract

The effects of taurine supplementation on the serum cholesterol levels and the progression of atherosclerosis were investigated in the hyperlipidemia- and atherosclerosis-prone Japanese (LAP) quail. The ingestion of a high-cholesterol diet containing 1% cholesterol by LAP quails for 60 days resulted in a marked elevation in serum non-HDL cholesterol and triglyceride, as well as severe aortic lesions with lipid droplets. An immunohistochemical study showed that the lesion consisted of mainly lipid-rich macrophages and T cells. Sixty-day taurine supplementation (1% in drinking tap water) to LAP quails fed high-cholesterol diet containing 1% cholesterol significantly reduced serum non-HDL cholesterol from 4,549 to 2,350 mg/dl. The serum triglyceride level also decreased after taurine supplementation from 703 to 392 mg/dl. Although the HDL cholesterol level significantly decreased due to the high-cholesterol diet, it recovered to the control level fed a regular diet in response to taurine. Bile acid production was stimulated and hepatic cholesterol was reduced by taurine supplementation. A quantitative analysis using aortic cross-sections showed that areas of oil-red O positive lipid accumulation significantly decreased by 74% after taurine supplementation. These results demonstrated the lipid-lowering and anti-atherosclerotic effects of taurine in a diet-induced hyperlipidemic LAP quail model. The prevention of atherosclerosis by taurine is mainly attributed to an improvement in the serum cholesterol and triglyceride levels, which may be related to changes in the hepatic cholesterol metabolism.

Dietary Taurine Reduces Hepatic Secretion of Cholesteryl Ester and Enhances Fatty Acid Oxidation in Rats Fed a High-Cholesterol Diet

“…Providing taurine as 5% of the diet for 14 d significantly decreased concentrations of cholesterol, especially cholesteryl esters in both serum and liver. Ketone body production and incorporation of exogenous [1][2][3][4][5][6][7][8][9][10][11][12][13][14] C]oleate into ketone bodies in liver perfusate were consistently higher during a 4-h perfusion period in taurine-fed rats than in control rats. The elevation was accompanied by increased activity of liver mitochondrial carnitine palmitoyltransferase, a rate-limiting enzyme for fatty acid oxidation.…”

“…Taurine (2-aminoethanesulfonic acid) was provided by Taisho Pharmaceutical (Saitama, Japan), while [1][2][3][4][5][6][7][8][9][10][11][12][13][14] C]oleic acid was purchased from Amersham Life Science (Buckinghamshire, England). Oleic acid and palmitoyl-CoA were obtained from Sigma Chemicals (St. Louis, MO).…”

“…In the present study, we therefore employed oleic acid as an exogenous fatty acid substrate. At the beginning of recirculation, 5 mL of 20 m M potassium [1][2][3][4][5][6][7][8][9][10][11][12][13][14] C]oleate (100 mol; specific activity, 0.25 MBq/ mmol) was added as an exogenous fatty acid, and the same solution was continuously infused at a rate of 4.5 mL/h (90 mol) by a mechanical infusion pump. At 1-h intervals, 20 mL of perfusate was taken for analyses of ketones and lipids.…”

“…Dietary taurine exhibits various physiologic and pharmacological actions, including hypocholesterolemic and antiatherogenic effects, in experimental animals, especially rats, mice, and Japanese (LAP) quail fed high cholesterol diets (1)(2)(3)(4)(5)(6). These beneficial effects of taurine have recently been reproduced in humans ( 7 , 8 ).…”

“…We therefore undertook a more detailed examination of fatty acid metabolism using an exogenous [1][2][3][4][5][6][7][8][9][10][11][12][13][14] C]oleic acid, and found for the first time that the reduced hepatic synthesis and secretion of cholesteryl ester resulting from dietary taurine intake stimulates oxidation of exogenous fatty acid at the expense of esterification.…”