Mackerel oil and atherosclerosis in pigs

Abstract

In 35 pigs atherosclerosis was induced by balloon abrasion and a diet containing 2% (w/w) cholesterol and 7% (w/w) lard fat. After 4 months of induction nine animals were killed (I) for analysis of the extent of atherosclerosis, while the diet of the other 26 pigs was changed to a low cholesterol diet containing either 9% (w/w) lard fat (L), 9% (w/w) fish oil (F) or 4.5% (w/w) lard fat and 4.5% (w/w) fish oil (LF). This diet was continued for 3 months to induce regression of atherosclerosis. The cholesterol-rich diet increased plasma total cholesterol, but did not affect plasma triglycerides. Low-cholesterol feeding decreased plasma total cholesterol in all three groups, but triglycerides only in LF and F. Lipid infiltration of the aortic wall was similar in I, L, LF and F. In the denudated coronary arteries of I mean luminal encroachment was 11 +/- 2%. This was similar in L (13 +/- 4%) but significantly lower (P less than 0.05) in LF (6 +/- 2%) and in F (3 +/- 1%). In the non-abraded coronary arteries of I mean luminal encroachment was 1.3 +/- 0.3%. For F and LF similar values were found, but in L there was an increase to 11 +/- 3% during low-cholesterol feeding. ADP-induced platelet aggregation was lower in LF and F than in L. Thromboxane A2 production was only reduced in F, while the production of the weak thromboxane A3 agonist was larger in F than in LF. It is concluded that fish oil retards the progression of and causes regression of coronary atherosclerosis.

Reduced proteoglycan binding of low density lipoproteins from monkeys (Macaca fascicularis) fed a fish oil versus lard diet.

“…In both dietary phases of the study, significant differences (/><0.05) in the number of LDL particles complexed to 1 versus lard. In phase 1, the mean number of LDL particles bound per microgram PG was 5.31±0.83 (xlO 12 ; mean±SEM) for LDL from animals fed the lard diet compared with 1.00±0.27 (xlO 12 ) for LDL from animals consuming the fish oil diet. When the experimental diets were reversed in phase 2 of the study, PG binding properties of the LDL were also reversed.…”

“…When the experimental diets were reversed in phase 2 of the study, PG binding properties of the LDL were also reversed. The mean number of LDL particles bound per microgram PG was 6.00±0.52 (xlO 12 ) and 3.56±0.67 (xlO 12 ) for LDL from animals fed the lard and fish oil diets, respectively. Figure 6 illustrates the change in LDL binding to PG for each animal in the study.…”

“…2 -5 Recently in a multiple risk factor intervention trial (MRFIT), a significant decline in risk of CHD was associated with increased consumption of &>-3 fatty acids when risk values were adjusted for age, race, blood pressure, plasma lipids, and cigarette smoking. 6 In addition, - 12 The cardioprotective effects of <w-3 fatty acids may result through several mechanisms. Considerable interest has focused on the decreased potential for thrombotic and inflammatory events due to substitution of cell membrane arachidonic acid (in animal fat-rich diets) by eicosapentaenoic acid (in fish oil-rich diets).…”

Development and regression of atherosclerosis in pigs. Effects of n-3 fatty acids, their incorporation into plasma and aortic plaque lipids, and granulocyte function.

“…39 In the delipidated extracts, DNA contents were measured as previously described. 25 For fatty acid analysis, plasma and aortic lipids were separated by thin-layer chromatography on Kieselgel 60 F254 plates (Merck, Darmstadt, FRG) activated at 110°C for 1 hour. The solvent system contained n-hexane/diethyl ether/acetic acid (60:40:1, vol/vol/vol).…”

Fish oil and the prevention and regression of atherosclerosis

“…For instance, fish off might change the physical and chemical state of plaque lipids, as well as the fluidity of plaque cellular components. So far, only four studies [28,76,106,107] reported on the additive effects of fish oil on the regression of atherosclerosis (Table 7). In swine, atherosclerosis was induced by endothelial denudation and high cholesterol feeding for 4 months, after which the animals were put on a low-cholesterol, fish oil (two doses) containing diet for 3 months [106].…”