Effects of dietary protein type on the response of lipid metabolism to orotic acid in rats

The effects of orotic acid supplementation to casein, egg protein, soy protein and wheat gluten diets on the lipids of liver and serum were compared. When orotic acid was added, the contents of total lipids and triacylglycerol in the liver of the casein group were significantly higher or tended to be higher than those of the other three dietary groups. Dietary orotic acid had no effect on the food intake. The liver weight, and liver total lipids, triacylglycerol, cholesterol and phospholipids were increased or tended to be increased by the addition of orotic acid. The serum triacylglycerol level was decreased by the addition of orotic acid to either the casein or soy protein diet. Thus, the response to liver lipid accumulation induced by orotic acid feeding depended on the dietary protein type.     

Effect of dietary fiber on the lipid metabolism and immune function of aged Sprague-Dawley rats

Eight-month-old Sprague-Dawley rats were fed on diets containing dietary fiber at the 5% level for 3 weeks to examine the effect on the lipid metabolism and immune function. Among cellulose, guar gum, partially hydrolyzed guar gum (PHGG), glucomannan and highly methoxylated pectin, guar gum induced a significant decrease in the food intake and weight gain, as well as a significant increase in the liver weight. In addition, the epidydimal adipose tissue weight of the rats fed on PHGG was significantly higher than that of the rats fed on cellulose. There was no significant effect on the serum lipid levels, but the serum IgG level of the rats fed on guar gum was significantly lower than that of the rats fed on cellulose. The IgA and IgG productivity in mesenteric lymph node (MLN) lymphocytes was significantly higher in the rats fed on guar gum, glucomannan and pectin than in those fed on cellulose, while the effect on Ig productivity in spleen lymphocytes was not as marked. In addition, only guar gum induced a significant increase of IgM productivity in MLN lymphocytes when compared to the cellulose group. These results suggest that enhancement of the immune function by dietary fiber is mainly expressed in the gut immune system.     

Effects of dietary sea squirt (Halocynthia roretzi) on lipid metabolism in rats

The effect of dietary sea squirt ( Halocynthia roretzi) on lipid metabolism in rats was investigated. Rats were fed sea squirt muscle (Experiment 1); sea squirt muscle, defatted sea squirt muscle and its hexane extract (Experiment 2); and whole body sea squirt and its parts as muscle or viscera (Experiment 3). All of the diets contained the same levels of protein (20%) and lipid (7%). In experiment 1, serum total cholesterol (T-Ch), very-low-density lipoprotein plus low-density lipoprotein (VLDL+LDL)-Ch, triglyceride (TG), phospholipid (PL) and nonesterified fatty acid (NEFA) levels were reduced by 20% dietary sea squirt muscle ingestion; steroid excretions into feces were enhanced by the same diet. In experiment 2, serum T-Ch, (VLDL+LDL)-Ch, TG, PL and NEFA levels were significantly reduced and steroid excretions into feces were significantly enhanced by ingestion of the sea squirt muscle hexane extract. Ingestion of defatted sea squirt muscle also reduced these serum lipid levels, but not as much as did that of whole sea squirt muscle. In experiment 3, serum T-Ch and HDL-Ch levels were significantly elevated by the 10% sea squirt viscera ingestion.     

Effects of diabetes on the dietary lipid alteration of R3230AC mammary carcinoma growth in rats

To examine the effects of diabetes on the alteration of R3230AC mammary tumor growth by dietary lipids, streptozotocin-induced diabetic rats were fed diets containing either 20% corn oil (HF), 20% hydrogenated cottonseed oil (HCTO), or 0% fat (FF). Diabetes resulted in lower tumor weights and body weights compared to those of intact animals. Unlike intact animals, relative tumor weight (g tumor/100 g body wt) of diabetic animals fed HF diets were not greater than those from animals fed FF diets. However, in these diabetic animals, growth of tumors in HF-fed rats was faster than in HCTO-fed rats, a relationship similar to that seen in intact rats. A surprising result was the almost twofold greater tumor weight/100 g body wt observed in diabetic FF-fed rats compared to those fed HCTO diets. Insulin binding to tumor plasma membranes from diabetic animals was higher in rats fed HF diets than in rats fed FF or HCTO diets. The tumor plasma membrane fatty acid composition of diabetic rats fed FF and HCTO diets displayed higher proportions of the monounsaturates (C18:1 and C21:1) and decreased amounts of the polyunsaturates (C18:2 and C20:4) compared to the levels observed in membranes from HF-fed rats. These results, as well as the insulin binding data, were similar to those obtained using intact animals. The data presented here indicate that the more rapid growth of the R3230AC mammary tumor seen in intact animals fed high polyunsaturated fat vs fat-free diets did not occur in diabetic animals.     

Influence of dietary hexachlorocyclohexane isomers on lipid metabolism in albino rats

Dietary intake of beta- and gamma-hexachlorocyclohexane (beta- and gamma-HCH) by albino rats for two weeks (at 800 ppm level) resulted in impairment of lipid metabolism, viz. hyperlipemia and fatty metamorphosis of liver. Liver fat content was increased by both beta- and gamma-HCH. Significant increases were observed in triglyceride and phospholipid fractions of blood in these experimental animals. The incorporation of [14C]acetate and palmitate into liver and blood lipids was higher in HCH pretreated animals, suggesting a higher rate of fat synthesis in liver and of secretion as well.     

Effects of castor oil on lipid metabolism in rats

Weanling rats were given diets contained castor oil (CAO-diet), coconut oil (CO-diet), or high-oleic safflower oil (HO-diet) each 10% (wt). No growth retardations were observed on the CAO-diets. The CAO-diet group showed significantly lower serum cholesterol and hepatic triacylglycerols than the HO-diet group. Ricinoleic acid was found at an extremely low level in perirenal adipose tissue.     

Dietary soybean protein moderates the deleterious disturbance of lipid metabolism caused by exogenous oxidized cholesterol in rats.

Effects of dietary protein on oxidized cholesterol-induced disturbance of lipid metabolism were examined in 4 week old male Sprague-Dawley rats, using casein and soybean protein as dietary protein source. The rats were given one of the two proteins in 0. 078% cholesterol (control), 0.25% cholesterol or 0.25% oxidized cholesterol mixture (containing 0.078% cholesterol) diets. Dietary oxidized cholesterol, compared to cholesterol, tended to inhibit hepatic sterol biosynthesis in casein-fed rats, whereas this inhibitory action was slightly moderated by intake of soybean protein. As a result, the hepatic 3-hydroxy-3-methylglutaryl-CoA reductase activity was rather higher in the rats fed oxidized cholesterol than in those fed cholesterol in the soybean protein-fed group. The hepatic cholesterol 7alpha-hydroxylase activity tended to be higher in the rats fed oxidized cholesterol than in those fed control diet in the soybean protein-fed group, despite the fact that oxidized cholesterol lowered the hydroxylase activity in the casein-fed group. On the other hand, dietary oxidized cholesterol tended to slightly enhance the hepatic Delta6 desaturase activity in the casein-fed group; however, this observation was not shown in the soybean protein-fed group. Moreover, dietary soybean protein facilitated fecal oxidized cholesterol excretion and simultaneously inhibited the accumulation of oxidized cholesterol in serum and liver. In conclusion, dietary soybean protein alleviated the deleterious actions of exogenous oxidized cholesterol on hepatic cholesterol and linoleic acid metabolism, although these efficacies were not necessarily significant. A great part of these moderations may be exerted by the specific hypocholesterolemic function of soybean protein, such as the stimulation of fecal oxidized cholesterol excretion, the change of hormonal release and modulation of lipoprotein catabolism.     

微量元素对糖尿病大鼠糖脂代谢的影响

目的观察微量元素铬对糖尿病大鼠糖脂代谢的影响。方法选糖尿病大鼠经灌胃给予有机铬水溶液治疗12周后,分别观察口服有机铬200μg/d及400μg/d的糖尿病大鼠空腹血糖及血脂水平(血清总胆固醇、甘油三酯、低密度脂蛋白和高密度脂蛋白)。实验分为4组:1组为正常对照组;2组为铬200μg/d组;3组为铬400μg/d组;4组为糖尿病对照组。结果有机铬具有明显降低血糖、血清总胆固醇、低密度脂蛋白和甘油三酯及升高高密度脂蛋白的作用(P0.05~P0.01)。结论有机铬能明显改善糖尿病大鼠的糖脂代谢。     

The influence of dietary protein on ascorbic acid metabolism in rats

1. d-Glucuronolactone reductase, l-gulonolactone oxidase, uronolactonase, dehydroascorbatase, l-gulonate dehydrogenase and l-gulonate decarboxylase have been measured in the tissues of rats fed on diets containing variable amounts of protein. Rats fed on a protein-free or a 2% casein diet for 15 days showed a marked decline in the activities of d-glucuronolactone reductase, l-gulonolactone oxidase, uronolactonase and dehydroascorbatase in the liver, and no change in l-gulonate dehydrogenase and l-gulonate decarboxylase activities in the kidney when compared with rats fed on diets containing 9%, 18% or 25% casein. Giving diets containing 60% or 88% casein to rats did not appreciably alter the activities of uronolactonase, dehydroascorbatase, l-gulonate dehydrogenase and l-gulonate decarboxylase, but inhibited considerably the activities of d-glucuronolactone reductase and l-gulonolactone oxidase in the liver, resulting in decreased synthesis of ascorbic acid. 2. Rats fed on a 25% casein diet showed maximal weight gain, higher tissue reserve of ascorbic acid and higher urinary excretion of both ascorbic acid and glucuronic acid when compared with rats fed on diets containing lower or higher amounts of protein.     

Effects of moderate riboflavin deficiency on lipid metabolism in rats

Dietary riboflavin intake of the people in Taiwan has been inadequate, while the fat intake has been increasing remarkably in recent years. Therefore, the effects of a moderate riboflavin deficiency on lipid metabolism in growing young rats fed diets containing 10, 25, or 40 percent calories of fat for 5 weeks were studied. The riboflavin deficiency status of the rats was certified by increased activity coefficients of erythrocyte glutathione reductase. Serum total lipids and cholesterol levels were significantly lower (P less than 0.05) in the medium fat-riboflavin deficient group. In the high fat-riboflavin deficient group, the growth and dietary intake were depressed and the liver weight/100 g body weight increased markedly (P less than 0.001). The liver total lipids, triglycerides, cholesterol and lipid peroxides of the high fat-riboflavin deficient group showed significant increases (P less than 0.025, P less than 0.025, P less than 0.05 and P less than 0.025 respectively), as compared with the pair-fed control groups. However, the increases were not significant in the medium fat and the low fat groups. The present study indicates that a high fat-riboflavin deficient diet would have adverse effects on lipid metabolism.     

Effects of dietary carbohydrate on cholesterol metabolism in rats and rabbits.

Semipurified diets produce a marked hypercholesterolemia in rabbits and tend to elevate the level of plasma cholesterol in rats. They also decrease rates of oxidation of [26-14C]cholesterol to respiratory 14CO2 and excretion of label in fecal lipid, compared with commercial feed. In both species, the hypercholesterolemia was prevented and the rate of oxidation of [26-14C]cholesterol increased by using unmodified potato starch as the carbohydrate component of the semipurified diets. Potato starch was poorly digested by rats but appeared to be well utilized by rabbits. A semipurifed diet containing cooked potato starch gave results in rats comparable to those obtained with diets containing other types of carbohydrate. Cooked potato starch produced diarrhea in rabbits, thus complicating interpretation of the results. When the diarrhea was treated with antibiotics, the results were similar to those obtained with other carbohydrates. Rats fed commercial diet which had been heated in an oven or autoclaved had higher plasma levels than those fed untreated commercial diet but no significant differences in rates of oxidation or excretion of cholesterol were observed.     

Effects of dietary oyster extract on lipid metabolism, blood pressure, and blood glucose in SD rats, hypertensive rats, and diabetic rats

Oyster extract was prepared by hydrolysis of oyster protein with proteases, Aloase (a protease from Bacillus subtilis), and Pancitase (a protease from Aspergillus oryzae). Rats were fed a diet containing 20% casein (the control diet) or 15% casein and 5% oyster extract (the oyster extract diet) as the protein source. The oyster extract diet exerted a significant reduction in serum cholesterol and liver triglyceride concentrations as compared with the control diet in Sprague-Dawley (SD) rats fed cholesterol-supplemented diets for 4 weeks. The activities of cytosolic fatty acid synthase and glucose-6-phosphate dehydrogenase were significantly lower in the oyster extract group than in the control group in the liver of SD rats. Hepatic cholesterol and triglyceride concentrations were significantly lower in spontaneously hypertensive (SH) rats and Otsuka Long-Evans Tokushima Fatty (OLETF) rats, type 2 diabetic rats, fed the oyster extract diet, for 4 weeks and 4 months respectively, than in those fed the control diet in the cholesterol-free diet. Blood pressure was significantly lower in the oyster extract group than in the control group at the 2nd and 4th weeks after the beginning of feeding experimental diets in SH rats. These results suggest that oyster extract prepared by hydrolysis of oyster induces triglyceride-lowering activity in the liver through a decrease in hepatic lipogenesis in SD rats, and that it exerts the antihypertensive effect in SH rats.     

Effects of acute and chronic sleep loss on immune modulation of rats

Sleep deprivation is now recognized as an increasingly common condition inherent to modern society, and one that in many ways, is detrimental to certain physiological systems, namely, immune function. Although sleep is now viewed by a significant body of researchers as being essential for the proper working of a host of defense systems, the consequences of a lack of sleep on immune function remains to be fully comprehended. The aim of the current study was to investigate how paradoxical sleep deprivation (PSD) for 24 and 96 h and sleep restriction (SR) for 21 days by the modified multiple-platform method, and their respective 24-h recovery periods, affect immune activation in rats. To this end, we assessed circulating white blood cell counts, lymphocyte count within immune organs, as well as Ig and complement production. The data revealed that PSD for 96 h increased complement C3 and corticosterone concentration in relation to the control group. In contrast, the spleen weight, total leukocytes, and lymphocytes decreased during SR for 21 days when compared with the control group, although production of a certain class of immunoglobulin, the IgM, did increase. After recovery sleep, lymphocyte count in axillary lymph nodes grew when rats had rebound sleep after PSD for 24 h, neutrophils increased after PSD 96 h and lymphocytes numbers were higher after SR 21 days. Such alterations during sleep deprivation suggest only minor alterations of nonspecific immune parameters during acute PSD, and a significant impairment in cellular response during chronic SR.     

Effects of altered photoperiod on circadian clock and lipid metabolism in rats

Disruption of circadian clock timekeeping due to changes in the photoperiod enhances the risk of lipid metabolism disorders and metabolic syndrome. However, the effects of altered photoperiods on the circadian clock and lipid metabolism are not well understood. To explore the effects of altered photoperiods, we developed a rat model where rats were exposed to either short-day or long-day conditions. Our findings demonstrated that altered photoperiods mediated circadian clocks by partly disrupting rhythmicity and shifting phase values of clock genes. We also showed that compared to long-day conditions, rats under short-day conditions exhibited more photoperiodic changes in a variety of physiological outputs related to lipid metabolism, such as significant increases in serum triglyceride (TG), high-density lipoprotein, and leptin levels, as well as increased body weight, fat:weight ratio, and hepatic TG levels. These increments were gained possibly through upregulated expression of forkhead box O1 (FoxO1), which partly mediates the expression of peroxisome proliferator-activated receptorα (PPARα) to increase the expression of phosphoenolpyruvate carboxykinase (PEPCK), peroxisome proliferator-activated receptor-g coactivator-1β (PGC1β), and fatty acid synthase (Fasn). In addition, the oscillation rhythms of FoxO1, PEPCK, PGC1β, and Fasn expression levels in the livers of rats exposed to a short-day photoperiod were more robust than those exposed to a long-day photoperiod. These findings suggest that a change in photoperiod can partly disrupt the circadian rhythmcity of clock genes, impair lipid metabolism, and promote obesity.     

Dietary effect of guar gum and its partially hydrolyzed product on the lipid metabolism and immune function of Sprague-Dawley rats

The dietary effect of the water-soluble dietary fibers (WSDF), guar gum, partially hydrolyzed guar gum (PHGG), glucomannan, highly methoxylated (HM) pectin, on the serum lipid level and immunoglobulin (Ig) production of Sprague-Dawley rats was compared with that of water-insoluble cellulose. Although serum total cholesterol and triglyceride levels were significantly lower in the rats fed with WSDF than in those fed with cellulose, a decrease in the level of phospholipids was only observed in the rats that had been fed on guar gum or glucomannan. In addition, all WSDF feeding enhanced IgA productivity in the spleen and mesenteric lymph node lymphocytes, although the increase in serum IgA level was only observed in the rats fed on WSDF, and not on PHGG. When mesenteric lymph node lymphocytes were cultured in the presence of various concentrations of guar gum or glucomannan, no significant increase in Ig production was apparent. These data suggest that WSDF indirectly enhanced the Ig production of lymphocytes, and that serum lipid reduction and IgA production-enhancing activities of WSDF were dependent on their molecular sizes.