Reduced Hepatic Triglyceride Secretion in Rats Fed Docosahexaenoic Acid–Rich Fish Oil Suppresses Postprandial Hypertriglyceridemia

Abstract

To evaluate the mechanisms of suppression of postprandial hypertriglyceridemia by fish oil rich in docosahexaenoic acid, the effect on the intestinal absorption of triglyceride, activities of lipoprotein lipase (LPL) and hepatic triglyceride lipase (HTGL) and metabolism of chylomicrons (CM) and CM remnants were compared with that of safflower oil in Sprague-Dawley rats in a series of studies. The feeding of fish oil for 3 wk suppressed postprandial hypertriglyceridemia (study 1). Dietary fish oil did not alter the rate of lymphatic absorption of triglyceride (study 2). The activities of LPL and HTGL were measured at 5 h after the beginning of feeding, when serum triglyceride concentrations were highest in both dietary groups. The activities of LPL in adipose tissue and heart were greater (P< 0.05) and those of HTGL were lower (P < 0.05) in the rats fed fish oil (study 3). In contrast, there were no differences in the activities of LPL and HTGL in postheparin plasma between the fish and safflower oil groups (study 4). The clearance rates of CM and CM remnants were measured by injecting intravenously CM collected from rats fed safflower or fish oils with [14C]triolein and [3H]cholesterol (study 5). Dietary oil did not influence the half-lives of CM or CM remnants. The secretion of triglyceride from the liver of rats injected with Triton WR-1339 was lower (P < 0.05) in the rats fed docosahexaenoic acid, a major component of fish oil, than those fed linoleic acid, a major component of safflower oil (study 6). These observations strongly support the hypothesis that in rats, the principal cause of the suppression of postprandial hypertriglyceridemia by fish oil is the depression of triglyceride secretion from the liver.

Omega-3 fatty acid supplementation accelerates chylomicron triglyceride clearance

“…Since clinically significant fat malabsorption has not been observed with fish oil supplementation, the most likely explanation for the reduced postprandial chylomicronemia is accelerated chylomicron clearance. Indeed, fat absorption was not reduced (30,31) and chylomicron lipids were cleared faster in fish oil-fed rats than in controls (32). However, the enhanced clearance hypothesis has never been directly tested in humans.…”

Soybean β-conglycinin improves carbohydrate and lipid metabolism in Wistar rats

“…In Experiment 2, at the end of the feeding period, after fasting for 6 h from early in the morning, blood was collected from the tail vein. Then, rats were administered tyloxapol (480 mg/kg body weight, SigmaAldrich, St. Louis, USA), an inhibitor of lipolysis, via the jugular vein, and blood was collected from the tail vein after 2 h. 12) Immediately after the blood collection, the rats were sacrificed by exsanguination from the aorta under ether anesthesia. The serum was separated from the blood by centrifugation.…”

Hypocholesterolemic Effects of Microbial Protease-Resistant Fraction of Katsuobushi in Ovariectomized Rats Depend on the Both Oil and Undigested Protein

“…Reduced intestinal absorption of dietary fish oil may contribute to reduced plasma TAG levels in the CϩEX, KBR and DF/ KBRϩEX groups. However, intestinal absorption of dietary fish oil has been reported to be unaltered compared to other oil sources (52,53).…”