F. Benhizia et al., EFFECTS OF A FISH-OIL LARD DIET ON RAT PLASMA-LIPOPROTEINS, LIVER FAS, AND LIPOLYTIC ENZYMES, American journal of physiology: endocrinology and metabolism, 30(6), 1994, pp. 50000975-50000982
The effects of a fish oil concentrate on blood lipids and lipoproteins
were examined in relation to their effects on liver fatty acid syntha
se (FAS), 3-hydroxy-3methylglutaryl-CoA (HMG-CoA) reductase, adipose t
issue lipoprotein lipase (LPL), and hepatic triglyceride lipase (H-TGL
). For 15 days, a-mo-old rats were fed a control diet (10% of calories
from fat, 4% fat by weight) or diets with 50% of calories (25% wt/wt)
provided by lard, lard and fish oil concentrate (35%/15%), or lard an
d corn oil (35%/15%). The high-lard diet increased plasma chylomicron
and liver triglycerides. The high-lard diet greatly decreased FAS, HMG
-CoA reductase, and LPL activities; it also reduced H-TGL activity. Co
mpared with the lard diet, the lard-fish oil diet decreased plasma TG
by drastically lowering chylomicron (4-fold, P < 0.001) and very-low-d
ensity lipoprotein levels(P < 0.001). It also reduced high-density lip
oprotein levels. The lard-fish oil diet prevented hepatic triglyceride
accumulation and decreased FAS activity and mass by 3.5-fold (P < 0.0
01) but did not further decrease HMG-CoA reductase activity. Adipose t
issue LPL activity was 2.5-fold (P < 0.001) higher with the lard-fish
oil diet than with the lard diet, and H-TGL activity decreased signifi
cantly (-32%, P < 0.01), despite unaltered levels of H-TGL mRNA. These
effects were significant with only 10% fish oil concentrate in the la
rd diet. They were not observed viith the lard-corn oil diet. Thus inc
lusion of fish oil concentrate in a lard diet results in a marked decr
ease in plasma chylomicron and very-low-density lipoprotein levels ass
ociated with an almost total suppression of hepatic FAS and a sustaine
d adipose tissue LPL activity. The decreased H-TGL activity may be a s
econdary adaptation to the induced hypolipidemia or may result from a
specific posttranscriptional inhibition of H-TGL gene expression by fi
sh oil n-3 fatty acids.