Tomoyuki Higuchi

Effect of Collagen Hydrolysates from Salmon and Trout Skins on the Lipid Profile in Rats

The effect of collagen hydrolysates from fish skins on lipid profile was assessed in rats administered chum salmon or rainbow trout collagen peptide. Single oral administration of soybean oil with or without one of either type of fish collagen peptide demonstrated that rat plasma triglycerides were significantly decreased 2 h later after the intake of oil and peptide mixtures (p < 0.05). The free and peptide forms of hydroxyproline derived from fish collagen peptides were statistically higher than those of zero time after oral administration. To test the effect of fish collagen peptides on continuous administration, rats were fed an AIN-93G purified diet containing 0.17% fish collagen peptide. The peptide groups had lower levels of plasma total lipids and triglycerides compared with the control group. However, the body, liver, and fat weights of rats were not significantly different between groups. These results suggest that fish collagen hydrolysates affect lipid absorption and metabolism in rats and may be useful in suppressing the transient increase of plasma triglycerides.

Reduction in Plasma Glucose after Lipid Changes in Mice Fed Fish Oil, Docosahexaenoic Acid, and Eicosapentaenoic Acid Diets

Background/Aim: Effects of the dietary docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and fish oil on weekly changes in plasma glucose, total cholesterol, triacylglycerol, and phospholipid concentrations of male Crlj:CD-1 mice were investigated. Method: Animals were fed five different experimental diets which contained 6.0% lard (lard diet), 6.0% fish oil (fish oil diet), 1.5% DHA-ethyl ester + 4.5% lard (DHA diet), 0.4% EPA-ethyl ester + 5.6% lard (EPA diet), and 1.5% DHA-ethyl ester + 0.4% EPA ethyl ester + 4.1% lard (DHA+EPA diet) for 17 weeks. Glucose and lipid concentrations in plasma collected at weeks 0, 1, 2, 4, 6, 8, 12, and 16 were measured. Results: Plasma phospholipid concentrations were significantly lower in mice fed the fish oil and DHA+EPA diets than in those fed the lard diet at week 2. Plasma total cholesterol and glucose concentrations were significantly lower in the fish oil diet group than in the lard diet group at weeks 6 and 8, respectively. Conclusion: These results indicate that the decreases in plasma glucose concentrations in response to intakes of DHA and EPA in mice take place over a longer period of time than similar decreases in the plasma lipid concentrations.

Effect of Erabu Sea Snake (Laticauda semifasciata) Lipids on the Swimming Endurance of Mice

Background/Aim: This study was designed to investigate the effect of Erabu sea snake (Laticauda semifasciata) lipids on the swimming endurance of mice. Method: Twelve-week-old male Crlj: CD-1 (ICR) mice were fed one of three experimental diets containing 6% lard, fish oil or sea snake lipids for 16 weeks. Swimming exercise was conducted in an acrylic plastic tank filled with 25 cm of water maintained at 23°C. Every 4 weeks, the mice were made to perform swimming exercises with loads attached to their tails, corresponding to approximately 1 or 2% of their body weights. Results: The group fed the sea snake lipid diet exhibited significantly improved swimming endurance compared with the lard diet group (p < 0.05); however, this result was not observed in the fish oil diet group. In the sea snake lipid diet group, plasma and muscle lactates were significantly lower, and plasma glucose and muscle glycogen were significantly higher than in the lard diet group (p < 0.05). Conclusion: These results suggest that the intake of sea snake lipids enhanced the swimming endurance of the mice by delaying the accumulation of lactate during swimming exercise.

A comparative study of the effects of erabu sea snake (Laticauda semifasciata) lipids, green tea extract and conjugated linoleic acid on the swimming endurance of mice.

The aim of this study was to assess the interaction between physical and biochemical parameters in mice fed 1 % sea snake lipids (SSL) and compare these with animals fed diets containing 0.2 % green tea extract (GTE) or 0.5 % conjugated linoleic acid (CLA). The swimming times of the SSL group were significantly increased at Weeks 12 and 16 (p<0.001), and those of the GTE group, at Week 12 (p<0.005), but not those of the control or CLA group, compared with those at Week 0. The increase tended to be significant in the SSL group compared with the control group at Week 12 (p=0.09). Both the SSL and GTE groups had significantly longer swimming times than the CLA group at Weeks 12 and 16 (p<0.001). After 5 minutes of swimming exercise, the SSL group exhibited significantly lower levels of plasma and muscle lactates (p<0.01), and plasma non-esterified fatty acid (NEFA) (p<0.001) than the control group. There were no significant differences in any of plasma glucose, muscle and liver glycogens, muscle lactate dehydrogenase (LDH), carnitine palmitoyltransferase (CPT), or monocarboxylate transporter 1 (MCT1) between SSL and control groups. The results suggest that the intake of 1 % SSL improved endurance more than the intake of 0.2 % GTE or 0.5 % CLA in mice. This action may involve the promotion of lactate oxidation for utilization.

Effects of Yogurt Supplemented with Fish Oil on Plasma Lipid and Glucose Concentrations, and Liver Lipid Contents in Mice

The aim of this study is to clarify the effects of yogurt supplemented with fish oil on plasma lipid and glucose concentrations, and hepatic lipid contents in mice. Male Crlj:CD-1 (ICR) mice were fed five experimental diets for 12 weeks. The experimental diets were as follows: without yogurt and fish oil (control diet); 10% (w/w) yogurt without fish oil [10% FO(-)]; 10% yogurt with fish oil [10% FO(+)]; 30% yogurt without fish oil [30% FO(-)]; 30% yogurt with fish oil [30% FO(+)]. Plasma triacylglycerol concentrations in the 10% FO(+) and 30% FO(-) groups were significantly lower than that in the control diet group (p < 0.05 and p < 0.05, respectively). Plasma total cholesterol and phospholipid concentrations were significantly lower in the 30% FO(+) group than in the control diet group (p < 0.005). Concentrations tended to be lower with supplementation with fish oil. Plasma glucose concentrations in the 10% FO(+) and 30% FO(+) groups were significantly lower than those in the control diet group (p < 0.005 and p < 0.01, respectively). Hepatic triacylglycerol and total cholesterol contents in the 30% FO(+) group were significantly lower than those in the control diet group (p < 0.05 and p < 0.005, respectively). These results suggest that plasma triacylglycerol and glucose concentrations are effectively decreased by supplementation of yogurt with fish oil.

Effect of lipids from erabu sea snake, Laticauda semifasciata, on plasma glucose, insulin, and adipocytokine concentrations of normal and streptozotocin-diabetic mice

Aims: To clarify the influence of Erabu sea snake lipid on levels of plasma insulin and adipocyte-derived hormones. Methods: Normal male mice (6 months) and streptozotocin-diabetic mice (a single administration, 150 mg/kg i.p.) were fed diets containing 10% fat as either lard or a mixture of 5% lard and 5% sea snake lipid for 4 months. Results: The normal mice on the sea snake lipid diet had a significantly lower plasma glucose concentration (198 ± 16 mg/dl; 148 ± 11 mg/dl) than those mice on the lard diet. Although plasma insulin concentrations were not influenced by the dietary fat type, leptin (10 ± 1 ng/ml; 16 ± 2 ng/ml) and adiponectin (18 ± 1 µg/ml; 21 ± 1 µg/ml) concentrations were significantly higher in the sea snake lipid group than in the lard group. However, these effects of a sea snake lipid intake were not evident in the streptozotocin-diabetic mice. Conclusion: The results suggest that the decrease in plasma glucose following the intake of sea snake lipids could be related to a corresponding increase in leptin and adiponectin level.