Pyridoxine and Atherosclerosis: Role of Pyridoxine in the Metabolism of Lipids and Glycosaminoglycans in Rats Fed Normal and High Fat, High Cholesterol Diets Containing 16 % Casein

Abstract

The effect of administration of low and high doses of pyridoxine on the metabolism of lipids and glycosaminoglycans was studied in rats fed normal and high fat, high cholesterol diets. Low doses of pyridoxine (0.005 mg/100 g body wt) caused increased concentrations of cholesterol and triglycerides in the serum and aorta in animals fed normal and high fat, high cholesterol diets. Administration of high doses of pyridoxine (5.0 mg/100 g body wt) caused decrease in the concentration of these lipids in these tissues except in the case of the aorta in the animals fed a normal diet. Low doses of pyridoxine generally caused a decrease in the concentration of many glycosaminoglycan fractions in the aorta in rats fed normal and high fat, high cholesterol diets, while high doses caused an increase. The activity of glucosaminephosphate isomerase (glutamine-forming) and UDPglucose dehydrogenase, both key enzymes in the biosynthetic pathway of glycosaminoglycans, decreased in rats given low doses of pyridoxine and increased in rats given high doses. The activity of many enzymes concerned with the degradation of glycosaminoglycans, hyaluronoglucosidase, .beta.-glucuronidase, .beta.-N-acetylglucosaminidase, aryl sulfatase and cathepsin D, generally increased in rats fed low doses of the pyridoxine and decreased in those given high doses. The concentration of hepatic 3''-phosphoadenosine-5''-phosphosulfate and the activity of the sulfate-activating system and of aryl sulfotransferase decreased when the dose of pyridoxine was low and increased when the dose was high.