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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.

SummaryRats were fed on three kinds of diets for two weeks: (I) basal diet, (II) containing 0.1% cholate and (III) containing 0.1% cholesterol and 0.1% cholate. Each dietary group was further divided into subgroups to whose diet was added 0, 5 or 10% (dry weight) of minced oyster (Callocorchina) or clam (Tapes japonica). The serum and liver cholesterol levels of the rats fed the basal diet were reduced by feeding oyster or clam. The serum and liver triglyceride levels of all dietary groups were lowered markedly by feeding oyster or clam. The activities of glucose-6-phosphate dehydrogenase, malic enzyme and acetyl-CoA carboxylase were markedly reduced in the basal groups fed oyster or clam. These effects were observed in 5 and 10% shellfish feeding. These shellfish may be considered hypolipidemic foods.

SummaryThe effects of fasting and refeeding on hepatic Z protein were investigated in rats. When [U-14C]palmityl-CoA was added to the liver cytosol fraction from fat-free refed rats, more binding of labeled palmityl-CoA to the Z-protein region was found than in the case of fasted rats. Also the radioactivities in specific precipitations of the palmityl-CoA binding protein with anti-Z immunoglobulin G were higher in the refed rats. The Z protein which stimulated diacylglycerol acyltransferase may be involved in the change of triacylglycerol synthesis in fasted and refed rat livers. Keywords Z protein, diacylglycerol acyltransferase, fasting and refeed ing Although the individual reactions in microsomal pathways of triacylglycerol synthesis in liver and other tissues are well defined (1-3), the factors which regulate the overall rate of liver triacylglycerol formation are not yet clear. Fallon et al. demonstrated that in rats fed on a high carbohydrate diet triacylglycerol formation in liver increased and correlated well with the activities of microsomal glycerophos phate acyltransferase and phosphatidate phosphatase (3-5). On the other hand, in a previous study using rat liver slices it was shown that triacylglycerol synthesis was markedly affected by fasting or refeeding the animals, phospholipid synthesis being virtually constant (6). It was suggested from the results that the syntheses of triacylglycerols and phospholipids are independently controlled. In view of the fact that triacylglycerols and phospholipids in liver are synthesized from a glycerophosphate to 1, 2-diacylglycerol in a common pathway (1), it seems reasonable to postulate that the synthesis of both lipids is regulated after the 1, 2 -diacylglycerol step rather than during the common steps. The present report provides evidence that the binding activity of palmityl-CoA to the Z protein, which is present in the cytosol of liver (7-9) and stimulates the activity of diacylglycerol acyltransferase (10), was higher in refed rats than in fasted rats.

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