Hyperlipidemia in rats fed retinoic acid.

This report describes a series of experiments that attempt to characterize the lipidemia accompanying retinoic acid administration. After feeding young adult male Sprague-Dawley rats, 1.2 Retinol Equivalents (R.E.) retinyl acetate plus supplemental retinoic acid (100 microgram/g dry diet) for three days and fasting for 6-8 hr, triglyceride, cholesterol, and phospholipid content of various serum lipoprotein fractions were determined. When compared to unsupplemented controls, both the serum very low density lipoprotein (VLDL) and the high density lipoprotein (HDL) fractions of the retinoic acid-fed rats were found to harbor an elevated triglyceride content. While VLDL cholesterol and phospholipid content were also elevated, total serum cholesterol and phospholipids were not statistically altered. The detergent Triton WR-1339 was used to depress serum triglyceride clearance in order to assess the effects of retinoic acid feeding on serum triglyceride levels. Triglyceride accumulation started earlier after Triton treatment and was greater when rats were fed 100 microgram/g retinoic acid for three days prior to testing. Red and white gastrocnemius muscle, cardiac ventricular muscle, and perirenal adipose tissue were removed from rats following retinoic acid feeding. Analysis of these tissues for lipoprotein lipase (EC 3.1.1.3) activity showed a decrease in adipose tissue, a large depression in both areas of gastrocnemius muscle and no change in cardiac muscle as a result of retinoic acid feeding.