Reduction of Lipogenic Enzymes by Shellfish Triglycerides in Rat Liver

Abstract

When rats were fed for 2 weeks on 3% fat diets containing 0.5 or 1%corbicula (Corbicula japonica PRIME), clam (Tapes japonica) or oyster (Callocorchina) triglycerides, serum and liver triglyceride levels were significantly lowered. The activities of hepatic glucose-6-phosphate dehydrogenase, malic enzyme and acetyl-CoA carboxylase were markedly reduced in the rats. Cholesterol synthesis by liver slices was also reduced. The results of immunochemical titrations and Ouchterlony double-diffusion analysis indicated that the decreases in the activities of acetyl-CoA carboxylase and glucose-6-phosphate dehydrogenase were due to decreases in the enzyme quantities. The shellfish triglycerides include a high percentage of long chain and polyunsaturated fatty acids, which are common to and characteristic of the three kinds of shellfish. They would be effective components in these observations.

The fat and protein fractions of freshwater clam (Corbicula fluminea) extract reduce serum cholesterol and enhance bile acid biosynthesis and sterol excretion in hypercholesterolaemic rats fed a high-cholesterol diet

“…However, the amount of plant sterols in the FCE used in our previous studies was not enough to explain this hypercholesterolaemic effect ( 5 , 6 ) , as compared with another study that investigated the hypocholesterolaemic effects of phytosterols ( 9 ) . It has also been noted that TAG prepared from freshwater clams have hypocholesterolaemic actions ( 4 ) . It seems possible that the hypocholesterolaemic actions of TAG from freshwater clams are elicited by PUFA ( 4 ) .…”

“…It has also been noted that TAG prepared from freshwater clams have hypocholesterolaemic actions ( 4 ) . It seems possible that the hypocholesterolaemic actions of TAG from freshwater clams are elicited by PUFA ( 4 ) . We have recently found that FCE exerted hypocholesterolaemic effects by increasing the faecal excretion of bile acids and by inducing CYP7A1 gene expression in hypercholesterolaemic rats fed a high-cholesterol diet ( 5 ) or a xenobiotic-containing diet ( 6 ) .…”

Dietary freshwater clam (Corbicula fluminea) extract suppresses accumulation of hepatic lipids and increases in serum cholesterol and aminotransferase activities induced by dietary chloretone in rats

“…Iritani et al 31) indicated that triglycerides prepared from the freshwater clam Corbicula japonica caused a reduction in hepatic levels of G6PD and ME. The sum Notes: Levels of mRNA for Cyp1a1 and Cyp2b1 were measured by northern blotting.…”

“…31) They speculated that these long-chain polyunsaturated fatty acids might be the active triglyceride components in freshwater clams that reduce lipogenesis. 31) Moreover, n-3 polyunsaturated fatty acids exert protective effects against liver injury by reducing TNF-α in the non-genetic model of non-alcoholic steatohepatitis in rats.…”

“…31) They speculated that these long-chain polyunsaturated fatty acids might be the active triglyceride components in freshwater clams that reduce lipogenesis. 31) Moreover, n-3 polyunsaturated fatty acids exert protective effects against liver injury by reducing TNF-α in the non-genetic model of non-alcoholic steatohepatitis in rats. 32) In fat fractions of FCE, the concentrations of oleic and linoleic acids (which are the major fatty acids in corn oil [control oil]) are less than one-thirteenth and one-fiftieth, respectively, of the concentrations found in corn oil.…”