Hypotriglyceridemic effect of n-3 fatty acids derived from tuna oh. or per1lla oil in rats

Abstract

In this study, we have compared the hypotriglyceridemic effect of n-3 fatty acids in rats fed diets containing different levels of tuna oil (27.2% DHA) or penlla oil (49.4% a-linolemc acid) mixed with beef tallow. Sprague-Dawley rats weighing between 300330g were fed a nutritionally complete se mi-synthetic diet containing tfl%(w/w) fat from one of the following sources'100% beef tallow (BT); 10. 40. or 70% of tuna oil plus 90. 60. or 30% of beef tallow (TIO, T40. or T70); 10. 40, 70% of perilla oil plus %. 60. or 30% of beef tallow (PIG, P40. or P70). for different feeding periods (10. 30. or 90 days). Triglycéride concentration of plasma was significantly lowered by tuna oil or perilla oil feeding, compared with beef tallow feeding, and this hypotriglyceridemic effect was more remarkable with higher content of tuna oil or perilla oil in diet and longer feeding period. Mitochondria! and peroxisomal β-oxidations of fatty acids were higher m tuna oii or perilla oil-fed groups than m beef tallow-fed group Tuna oil feeding caused greater peroxisomal β-oxidation compared with perilla oil feeding. Activities of ac\l-CoA 1.2-diac\lgl\cerol ac\ Itransferase and phosphatidate phosphohjdrolasc were lowest in tuna oiT-fed groups, followed b> perilla oil-fed groups and then beef tallow-fed group. The activities of these enzymes decreased with higher content of tuna oil (TIO > T40 sl'70) in diet but slightly increased(not significant) with higher content of perilla oil (PIO < P40 s" P70) in diet, which trend was showed in triglycéride concentration of liver. Hepatic triglycéride secretion was lower in tuna oil or perilla oil-led groups than in beef tallow-fed group. Lipoprotein lipase (LPL) activity of epididymal fat pad was higher in tuna oil fed-groups than in periîla oil and beef tallow-fed groups and LPL activity of heart was highest in perilla oil-fed groups, followed by tuna oil-fed groups and then beef tallow-fed group These data suggest that hypotriglyceridemic effect of tuna oil is due to an increase in fatty acids β-oxidation (especially in pcroxisome) and lipoprotien-catabolizing enzyme (LPL) activities of peripheral tissues, and/or a decrease of activities of enzymes related to triglycéride synthesis and triglycéride secretion in liver Trigl>ceride-lowering effect of perilla oil resulted mainl> from a decrease in hepatic trigl>ceride secretion as well as from an increase m fatty acids [I-oxidation and LPL activity of bean.