In vivo meal model for the evaluation of agents which affect the absorption of triglyceride and cholesterol

A meal model in which rats were trained to consume within 2 hr a high fat meal containing glycerol tri[1- 14 C]oleate and [ 3 H]cholesterol was compared to the corn oil bolus model. In the meal model, dietary triglyceride was absorbed from the small intestine faster during the first 6–8 hr and more completely than intubated corn oil, as determined by analysis of intestinal contents, serum radioactivity, serum triglycerides, adipose tissue and liver lipids. The effects of Cholestyramine, Colestipol and Pluronic L-101 (1% dietary admixes) on these variables were evaluated for 5 days in the meal model. Lipid absorption during a 72-hr period was reduced by all compounds. The per cent excretion of glycerol tri[1- 14 C]oleate was increased significantly by Pluronic L-101 (10-fold), Cholestyramine (5.7-fold) and Colestipol (2.7-fold). The excretion of [ 3 H]cholesterol was enhanced significantly by Cholestyramine (1.6-fold) and Colestipol (1.3-fold). The following observations were made 4hr after the initiation of the meal. Pluronic L-101 increased significantly the retention of glycerol tri[1- 14 C]oleate and [ 3 H]cholesterol in stomach (380 and 375 per cent, respectively), and of glycerol tri[1- 14 C]oleate in the small intestine (1100 per cent). The percent of intestinal lipid remaining as triglyce-ride from the intestinal lumen was increased significantly by Pluronic L-101 (160 per cent). Pluronic L-101 reduced significantly [ 14 C]lipid and [ 3 H]cholesterol in liver; Cholestyramine and Colestipol suppressed only [ 3 H]cholesterol. In adipose tissue, Pluronic L-101 treatment reduced significantly [ 14 C]lipid content only; Cholestyramine and Colestipol suppressed selectively [ 3 H]cholesterol. After 5 days of treatment, only Pluronic L-101 treatment resulted in significantly reduced serum triglycerides (32 per cent), cholesterol (21 per cent) and glucose (15 per cent). These data suggest that this in vivo meal-feeding model provides a physiological technique for evaluating agents affecting lipid absorption.