Reversion by taurine but not by glycine of ovarian hormone deficiency - induced hypercholesterolemia in aged rats is associated with increased fecal bile acids

The effect of taurine and glycine on the ovarian hormone deficiency-associated increase in plasma cholesterol concentration were studied in ovariectomized (ovx) 10-month-old retired breeder female rats. Rats was randomly assigned to four treatment groups: sham-operated+a casein-based cholesterol-free diet (C-diet, sham-C); ovx+C diet (ovx-C); ovx+C diet supplemented by taurine (50 g/kg diet, ovx-T); and ovx+C diet supplemented with glycine (50 g/kg diet, ovx-G). Rats were fed these diets for 28 d and killed at midnight in a fed state. Plasma and liver cholesterol concentrations in ovx-C were significantly higher than in sham-C. Bile flow, biliary bile acid secretion and fecal bile acid excretion were not significantly different between sham-C and ovx-C. Plasma cholesterol concentrations in ovx-T and ovx-G were significantly lower than those in ovx-C. Liver cholesterol concentration in ovx-G was significantly higher than in ovx-C but not in ovx-T. Cholesterol 7a-hydroxylase, bile flow, biliary bile acid secretion and fecal bile acid excretion in ovx-T were significantly higher than in ovx-C, but not in ovx-G. These results indicate that in the case of taurine but not glycine, increased fecal bile acid excretion is one of the factors in the prevention of the ovarian hormone deficiency-associated increase in plasma cholesterol concentration.     

Predominant conjugation with glycine of biliary and lumen bile acids in rats fed on pectin

1. Bile acids were analysed in the bile and lumen samples of rats which received a cholesterol-free or cholesterol-enriched (5 g/kg) diet free from fibre, or containing cellulose or citrus pectin at the level of 100 g/kg. 2. Dietary pectin but not cellulose increased biliary bile acid concentration and excretion. Dietary cholesterol did not affect biliary bile acids quantitatively. 3. Biliary bile acids were almost exclusively conjugated with glycine or taurine in the various experimental situations. The predominant portion of bile acids in rats fed on the cholesterol-free diet was conjugated with taurine when the diet was either free from fibre or contained cellulose; the ratio of bile acids conjugated with glycine: those conjugated with taurine (G:T) was less than 0.2. In contrast, with pectin as a fibre source, the conjugation with glycine increased enormously (G:T increased to approximately 4). Cholesterol enrichment of the diet also increased the glycine conjugation in all groups of rats. Even in this situation, the G:T was highest in rats fed on pectin. 4. Pectin, but not cellulose, increased the bile acid content of the small intestine and caecum, both in rats fed on the cholesterol-free and cholesterol-enriched diets. Cholesterol feeding doubled the bile acid content of the caecum in rats fed on a fibre-free diet or a cellulose diet, but not in those fed on pectin. No such effect of cholesterol was observed in the small intestine, except for the ileal bile acid content in rats fed on cellulose. 5. A considerable portion of the bile acids in the small intestine was deconjugated. The extent of the deconjugation was higher in the ileum than in the jejunum. As in the bile, G:T in rats fed on pectin (3-5.5) were higher than those in the other groups (0.05-1.05) in various situations. Also, cholesterol feeding considerably increased the ratio in all groups of rats. 6. The observed dietary alteration of the partition of bile acids between glycine and taurine may be of physiological significance in regulating bile acid and lipid metabolism in rats.     

The effect of taurine on the cholesterol metabolism in rats fed diets supplemented with cholestyramine or high amounts of bile acid

The effects of taurine on serum cholesterol levels and hepatic cholesterol 7alpha-hydroxylase activity (CYP7A1) were studied in rats fed cholestyramine or high amounts of sodium cholate in order to alter the intestinal pool of bile acids. Rats were fed a diet supplemented with 1% cholesterol and 0.25% sodium cholate (high cholesterol, control; C), and C supplemented with 4% cholestyramine (CH) or 0.75% sodium cholate (BA) for 14 d. Taurine groups were fed the diet supplemented with 3% taurine (CT, CHT and BAT). Compared to rats fed C and BA diets, serum cholesterol levels were significantly reduced in rats fed CT and BAT diets, but a significant reduction of serum cholesterol by taurine feeding was not observed in the CHT group as compared to the CH group. An increase in hepatic CYP7A1 activity due to taurine intake was observed in the CT and BAT groups. However, the simultaneous administration of cholestyramine and taurine (CHT group) did not increase hepatic CYP7A1 activity compared the intake of cholestyramine only (CH group). A significant increase in fecal bile acid excretion due to taurine intake was found only in rats fed the CT diet. In conclusion, it is suggested that taurine facilitates hepatic CYP7A1 activity regardless of the enlarged intestinal pool of bile acids due to increased intake of exogenous bile acid, and then reduces the serum cholesterol concentration.     

Excessive cholesterolemic response in analbuminemic rats fed a cholesterol-rich diet containing casein.

Female Nagase analbuminemic rats and Sprague-Dawley rats were fed purified diets with or without 1% cholesterol and containing either soybean protein or casein. After consuming the cholesterol-free diets, the analbuminemic rats had significantly higher plasma cholesterol and triglyceride concentrations than the Sprague-Dawley rats. The higher plasma cholesterol levels were essentially in the low density and high density lipoproteins. Based on the fact that the analbuminemic rats excreted more bile acids in feces it is possible that the higher baseline plasma cholesterol concentrations in Nagase analbuminemic rats were partly caused by overproduction of cholesterol. The Nagase analbuminemic rats displayed a greater cholesterolemic response to cholesterol feeding than Sprague-Dawley rats, but only if casein was the protein source in the diet. Casein vs. soybean protein in either cholesterol-free or high cholesterol diets reduced bile acid excretion in Sprague-Dawley but not in Nagase analbuminemic rats. The increased sensitivity to casein plus cholesterol feeding in Nagase analbuminemic rats may be caused by a lack of inhibition of de novo cholesterol synthesis.     

Cholesterol-lowering in hamsters fed rice bran at various levels, defatted rice bran and rice bran oil.

This study was conducted to determine the relative cholesterol-lowering effects of several levels of full-fat rice bran in hamsters. In addition, the separate effects of defatted rice bran and/or crude rice bran oil were investigated at levels equivalent to those present in 43.7% full-fat rice bran. Diets containing 10.9, 21.8, 32.8 or 43.7% full-fat rice bran, 35% defatted rice bran and/or 9% rice bran oil were fed to 4-wk-old male hamsters. All diets contained 10% total dietary fiber, 9% fat and 3.2% nitrogen; hypercholesterolemic diets contained 0.3% cholesterol; two diets were cholesterol-free, i.e., 10% cellulose and 43.7% full-fat rice bran. After 21 d, plasma and liver cholesterol, plasma triglycerides and liver weights were significantly greater in hamsters fed the 10% cellulose diet with 0.3% cholesterol compared with those fed the cholesterol-free cellulose diet. In animals fed cholesterol-free diets, plasma cholesterol values were significantly lower in those fed the 43.7% full-fat rice bran diet than in those fed the cellulose diet. In animals fed cholesterol-containing diets, plasma and liver cholesterol were significantly lower in animals fed the 43.7% full-fat rice bran diet than in those fed the cellulose diet. Plasma cholesterol reductions were significantly correlated to the level of rice bran in the diet. In cholesterol-fed hamsters, total liver cholesterol content was significantly lower in those fed the defatted rice bran diet with rice bran oil compared with those fed the cellulose diet. Full-fat rice bran was the only treatment that significantly lowered both plasma and liver cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dietary taurine alters ascorbic acid metabolism in rats fed diets containing polychlorinated biphenyls

The effect of dietary taurine on ascorbic acid metabolism and hepatic drug-metabolizing enzymes was investigated in rats fed diets containing polychlorinated biphenyls (PCB) to determine whether taurine has an adaptive and protective function in xenobiotic-treated animals. Young male Wistar rats (60 g) were fed diets containing 0 or 0.2 g/kg diet PCB with or without 30 g/kg diet of taurine for 14 d. The rats fed the PCB-containing diets had greater liver weight, higher ascorbic acid concentrations in the liver and spleen and greater hepatic cytochrome P-450 contents than control rats that were not treated with PCB (P < 0.01). In PCB-fed rats, urinary ascorbic acid excretion was enhanced, and serum cholesterol concentration (especially HDL-cholesterol) was significantly elevated compared with those in control rats. Dietary taurine significantly potentiated the increases in the urinary excretion of ascorbic acid and the rise in the levels of cytochrome P-450 which were caused by PCB treatment. On the other hand, the supplementation of taurine to control diet did not alter these variables. Taurine may enhance the hepatic drug-metabolizing systems, leading to the stimulation of the ascorbic acid metabolism in rats fed diets containing PCB.     

Dietary taurine or glycine supplementation reduces plasma and liver cholesterol and triglyceride concentrations in rats fed a cholesterol-free diet

The effects of dietary supplementation of taurine or glycine, the two amino acids involved in bile acid conjugation in the liver, on plasma and hepatic lipid concentrations were evaluated in rats fed a cholesterol-free diet. Three groups of male rats (140150g) were fed a cholesterol-free diet (CFD), a taurine-supplemented diet (TSD; CFD + 1.5% taurine) or a glycine-supplemented diet (GSD; CFD + 1.5% glycine) for 5 weeks. There was no significant difference in organ weights and cumulative body weight gain between groups at the end of the experimental period. Plasma triglyceride level was significantly lower in rats fed the TSD (53% decrease, P<0.001) compared to those fed the CFD. Both TSD and GSD significantly lowered the plasma levels of total cholesterol (40% decrease in TSD, p<0.001 and 27% decrease in GSD, p<0.001, respectively) and LDL-plus VLDL-cholesterol (50% decrease in TSD, p<0.05 and 39% decrease in GSD, p<0.01, respectively) compared to the values for CFD. Liver cholesterol concentration was not significantly influenced by the dietary supplementation of taurine or glycine. However, both TSD and GSD showed significantly lower hepatic triglyceride concentrations (43% and 53% decreases in TSD and GSD, p<0.001, respectively), and elevated hepatic free fatty acid levels (77% increases in both groups, p<0.001) compared to the values for CFD. These results suggest the possible roles of dietary taurine or glycine as hypocholesterolemic and/or hypotriglyceridemic agents.     

Dietary taurine enhances cholesterol degradation and reduces serum and liver cholesterol concentrations in rats fed a high-cholesterol diet.

The effect of taurine on hypercholesterolemia induced by feeding a high-cholesterol (HC) diet (10g/kg) to rats was examined. When various amounts of taurine (0.25, 0.5, 1, 2.5, 5, 10, 20, 30, 40 or 50 g/kg diet) were supplemented to HC for 2 wk, serum total cholesterol gradually and significantly decreased in a dose-dependent manner and normalized at the dose of 10 g taurine/kg, compared with the control (cholesterol free) diet group. By contrast, serum HDL-cholesterol was elevated by taurine supplementation. The HC diet caused a significant decrease in the concentration of taurine in serum, liver and heart compared to that in the control group, and the effective dose of supplemental taurine to improve its reduction was 2.5 g/kg diet. In the hypercholesterolemic rats fed the HC diet, the excretion of fecal bile acids and hepatic cholesterol 7 alpha-hydroxylase (CYP7A1) activity and its mRNA level increased significantly, and the supplementation of taurine further enhanced these indexes, indicating an increase in cholesterol degradation. The abundance of mRNA for Apo A-I, one of the main components of HDL, was reduced by HC and recovered by taurine supplementation. Agarose gel electrophoresis revealed that, in hypercholesterolemic rats fed the HC diet, the serum level of the heavier VLDL increased significantly, but taurine repressed this increase and normalized this pattern. Significant correlations were observed between the time- and dose-dependent increases of CYP7A1 gene expression and the decrease of blood cholesterol concentration in rats fed the HC diet supplemented with taurine (time, r = -0.538, P < 0.01, n = 32; dose, r = -0.738, P < 0.001, n = 20). These results suggest that the hypocholesterolemic effects of taurine observed in the hypocholesterolemic rats fed the HC diet were mainly due to the enhancement of cholesterol degradation and the excretion of bile acid.     

High dietary iron concentrations enhance the formation of cholesterol oxidation products in the liver of adult rats fed salmon oil with minimal effects on antioxidant status

The aim of this study was to investigate the effect of high dietary iron concentrations on the antioxidant status of rats fed two different types of fat. Four groups of male adult Sprague-Dawley rats were fed diets with adequate (50 mg iron supplemented per kg diet) or high (500 mg iron supplemented per kg diet) iron concentrations with either lard or salmon oil as dietary fat at 100 g/kg for 12 wk. The antioxidant status of the rats was profoundly influenced by the type of fat. Rats fed salmon oil diets had higher concentrations of thiobarbituric acid-reactive substances (TBARS) (P < 0.001), various cholesterol oxidation products (COP) (P < 0.001), total and oxidized glutathione (P < 0.05) and a lower concentration of alpha-tocopherol (P < 0.05) in liver and plasma than rats fed lard diets. The iron concentration of the diet did not influence the concentrations of TBARS, the activities of superoxide dismutase and glutathione peroxidase or the concentration of alpha-tocopherol in plasma or liver. The activity of catalase (P < 0.01) and the concentrations of total, oxidized and reduced glutathione (P < 0.05) in liver were slightly but significantly higher in rats fed high iron diets than in rats fed adequate iron diets, irrespective of the dietary fat. Rats fed the high iron diets with salmon oil, moreover, had higher concentrations of various COP in the liver (P < 0.001) than rats fed adequate iron diets with salmon oil. These results suggest that feeding a high iron diet does not generally affect the antioxidant status of rats but enhances the formation of COP, particularly if the diet is rich in polyunsaturated fatty acids.     

Effects of taurine on plasma and liver lipids, erythrocyte ouabain sensitive Na efflux and platelet aggregation in Sprague Dawley rats

The effects of taurine on plasma and liver cholesterol, erythrocyte ouabain sensitive Na efflux and platelet aggregation were examined in Sprague Dawley rats fed control or 0.5% cholesterol with 0.2% cholate diet. Plasma and liver levels of total cholesterol were increased significantly (p<0.05) in rats fed cholesterol diet compared to the control, and taurine significantly decreased the elevated plasma level of cholesterol in rats fed cholesterol diet (p<0.05). HDL-cholesterol was decreased in groups fed the cholesterol diet regardless of taurine supplementation and the difference between groups with and without cholesterol was significant (p<0.01). Plasma triglyceride was decreased and liver triglyceride was increased both significantly (p<0.05) in rats fed cholesterol compared to the control. Plasma and liver triglyceride in rats fed taurine was decreased significantly compared to the control (p<0.05). Intracellular Na tended to be lower in rats fed cholesterol or taurine and higher in rats fed cholesterol plus taurine compared to the control. Na efflux through Na-K ATPase and the passive leak of Na was somewhat reduced in rats fed cholesterol or taurine and was augmented in rats fed cholesterol plus taurine compared to the control, which showed a similar trend to the intracellular Na. Taurine supplementation caused a suppression of Na efflux in groups fed control diet and restored the suppressed Na efflux in groups fed cholesterol. Platelet aggregation was significantly decreased in the group fed taurine compared to the control (p<0.05) and the group fed cholesterol plus taurine was also a little lower in aggregation than the group fed cholesterol. Microscopic examination showed that taurine prevented fatty liver in rats fed cholesterol diet. Taurine known for stimulating Na-K ATPase in some cell types rather decreased erythrocyte ouabain sensitive Na-K ATPase in the present study. Taurine had hypolipidemic and hypocholesterolemic effects and inhibited platelet aggregation which may be favorable for prevention of cardiovascular diseases.     

Lipoprotein lipid and protein responses to dietary fat and diabetes in rats

Dietary and insulin-deficiency types of hyperlipidemia were compared in adult normal and streptozotocin-induced diabetic male breeder rats. High beef tallow, high corn oil or low fat diets (BT, CO and LF, respectively) were fed ad libitum for 2 months. Glucose and insulin were measured in plasma and total cholesterol, free cholesterol, cholesteryl ester, triglycerides and apoproteins in very low density, low density and high density lipoproteins (VLDL, LDL and HDL, respectively). Diet did not affect plasma glucose or insulin levels. LDL-triglycerides were higher in BT and diabetic than in CO and LF rats. HDL-free cholesterol levels were higher in CO- and LF-than in BT-fed rats. Diabetes resulted in a decrease in HDL-cholesterol. Diabetic animals had higher HDL-apoA-I (apolipoprotein A-I) levels than did CO- and LF- but not BT-fed rats. VLDL-triglycerides were higher in diabetic than in normal rats, with no dietary differences in normal rats. In LDL, apoB levels were lower and apoE levels were higher in LF-fed rats than in animals fed high fat diets. Diabetes resulted in an increase in LDL-apoB but a decrease in LDL-apoE. HDL-apoE levels were higher, although HDL-apoA-I levels were lower in LF than in high fat-fed rats. The results related to lipoprotein composition supported the hypothesis that excess intake of a diet high in saturated fat may contribute to a metabolic pattern that resembles that of a diabetic state.     

大鼠饲料中补充牛磺酸对血、肝胆固醇水平的影响

本文采用半合成低胆固醇或高胆固醇饲料研究添加不同剂量的牛磺酸对wistar大鼠血及肝中胆固醇水平的影响。结果表明:牛磺酸对大鼠血胆固醇水平的作用与实验期长短和饲料中添加牛磺酸的含量有关。在第三周末,实验组大鼠血胆固醇、血甘油三酯及肝胆固醇水平显著低于对照组,但肝脂肪总量无明显变化;高胆固醇饲料中添加牛磺酸后,大鼠血清高密度脂蛋白胆固醇水平有升高趋势,致动脉粥样硬化指数明显改善,提示牛磺酸可能有促进肝胆固醇分解并对预防动脉粥样硬化的发生有作用。     

Soluble dietary fiber and cholesterol influence in vivo hepatic and intestinal cholesterol biosynthesis in rats.

Ninety-six male Sprague-Dawley rats were randomly assigned to eight dietary treatments. Rats were fed, with ad libitum access, diets containing 10% dietary fiber as cellulose (control), pectin, psyllium or oat bran with or without 0.3% added cholesterol for 3 wk. Among cholesterol-fed rats, liver total cholesterol was significantly lower in rats fed diets supplemented with either pectin or psyllium compared with those fed cellulose. In contrast, rats fed oat bran with cholesterol had significantly higher liver cholesterol concentrations compared with cellulose-fed animals. Liver total lipid concentrations were significantly lower in groups fed pectin and psyllium with or without dietary cholesterol compared with cellulose-fed controls. Pectin feeding with or without dietary cholesterol significantly lowered plasma total cholesterol compared with cellulose feeding. Oat bran had no effect on plasma total cholesterol compared with control diets. Hepatic sterol synthesis was significantly greater for animals fed soluble dietary fibers compared with those fed cellulose, but the effect on intestinal sterol synthesis was less pronounced.     

Dietary cholesterol-fat type combinations and carbohydrate and lipid metabolism in rats and mice

In rats fed semipurified cholesterol-free diets, dietary corn oil induced higher levels of liver cholesterol, but lower concentrations of plasma cholesterol, plasma triglycerides and blood D-3-hydroxybutyric acid, than did coconut fat. Addition of cholesterol to the diets (1%, w/w) greatly increased liver cholesterol levels but did not affect the corn oil effect upon liver and plasma cholesterol. In contrast, dietary cholesterol prevented the corn oil effects upon plasma triglycerides and blood D-3-hydroxybutyric acid. Liver glycogen levels in rats increased significantly after cholesterol feeding, the effect being independent of dietary fat type. In mice, dietary corn oil, compared to coconut fat, elevated liver cholesterol only when the diet contained cholesterol. Corn oil caused an increase of liver glycogen in mice in the presence, but not in the absence of dietary cholesterol. This study shows that dietary cholesterol-fat type combinations influence various aspects of lipid and carbohydrate metabolism in rats and mice.     

Dietary grape seed tannins affect lipoproteins, lipoprotein lipases and tissue lipids in rats fed hypercholesterolemic diets

The effects of monomeric and polymeric grape seed tannins on rat plasma lipoproteins, lipoprotein lipase, hepatic lipase and aortic and hepatic lipid concentration were studied. Male Sprague-Dawley rats received either a normal diet (with no added cholesterol and no tannins), a control diet (hypercholesterolemic diet) or hypercholesterolemic diets supplemented with 2% tannin monomers or 2% polymers 3 or 9 wk. Plasma total cholesterol, triacylglycerol, LDL cholesterol and VLDL concentrations were significantly higher and the HDL cholesterol concentration lower in controls and in rats fed the diet supplemented with monomers compared with rats fed polymeric tannins at both time points. Lipoprotein lipase and hepatic lipase activities were significantly higher in control and in monomer-fed groups than in the polymer-fed group. Hepatic and aortic cholesterol and triacylglycerol concentrations were significantly higher in control rats and those fed monomers than in the polymer-fed group. Moreover, plasma HDL cholesterol and hepatic lipase activity were closely associated with low aortic cholesterol and triacylglycerol in rats fed polymeric tannins. These rats also exhibited greater fecal excretion of cholesterol and especially bile acids than the control or monomer-fed groups. Thus dietary grape seed tannins have a pronounced anti-hypercholesterolemic effect by enhancing reverse cholesterol transport and also by reducing intestinal cholesterol absorption and increasing bile acid excretion.     

Dietary casein and soybean protein affect the concentrations of serum cholesterol, triglyceride and free amino acids in rats.

This work was undertaken to investigate the concentrations of free amino acids in blood after food was withheld from growing, male Wistar rats fed cholesterol-free, low fat (1 g corn oil/100 g) diets with casein or soybean protein for 2 wk. A diet containing 22.5 or 23.5 g/100 g of soybean protein was hypocholesterolemic compared with a diet containing 20.0 g casein/100 g diet. A comparison of serum amino acids in soybean protein-fed vs. casein-fed rats showed that, whereas concentrations of many amino acids were lower in the soybean protein-fed rats compared with the casein-fed groups, glycine was the only amino acid having a higher concentration. Further, alanine was significantly lower in the soybean protein-fed rats compared with the casein-fed rats, and the protein-induced differences in glycine and alanine concentrations of unfed rats were reproducible. When diets containing 15.0% casein or 30.0% soybean protein, a casein diet supplemented with glycine and a soybean protein diet supplemented with methionine were compared, the changes in serum glycine and alanine correlated with the changes in serum cholesterol. Concentrations of several amino acids, particularly valine, leucine and tyrosine, also changed when serum cholesterol concentrations varied, but these effects could not be explained by our experiments. The results suggest that a change in serum concentration of glycine and alanine of unfed rats may be related to the change in serum cholesterol concentration.     

Effect of dietary taurine on cholesterol gallstone formation and tissue cholesterol contents in mice

The inhibitory effect of dietary taurine on cholesterol gallstone formation was studied using male mice of Jcl:ICR strain. Mice were provided three kinds of semi-purified diet; a cholesterol-free diet (standard), a lithogenic diet containing 0.5% cholesterol and 0.25% sodium cholate (C-CA), and a lithogenic diet supplemented with 5% taurine. The changes of total cholesterol in serum, cholesterol mass in the liver and the gall bladder, and gallstone incidence were studied as a function of time. Gallstone formation was observed only in the mice fed on the C-CA diet for more than 3 weeks. The changes of serum cholesterol concentration were not consistent with gallstone formation. The cholesterol mass of the liver in taurine-supplemented mice decreased after the 3rd week. Cholesterol content of the gall bladder increased with cholesterol gallstone formation. Therefore, the inhibitory effect of dietary taurine on cholesterol gallstone formation may be related to the decrease in cholesterol content of the liver.     

Activity of L-cysteinesulfinate carboxy-lyase and persulfurase in livers of rats fed different levels of sulfate and cysteine.

Activity of L-cysteinesulfinate carboxy-lyase (CSC) and persulfurase was measured in livers of rats fed 15% casein diets supplemented with (1) 0.53% cysteine, (2) 0.40% cysteine, (3) 0.40% cysteine + 0.10% sulfate, (4) 0.42% sulfate, or (5) 0.42% sulfate + 0.40% cysteine. The diets were fed to adult rats for 1 week and to weanling rats for periods of 1 and 4 weeks. At the end of each feeding period, the highest CSC activity was detected in livers from animals fed diet 4, but no differences in CSC activity were detected among livers from the other four groups. Persulfurase activity did not differ significantly among those weanling or adult rats fed the diets for 1 week but was lower among those fed diet 4 than diet 5 for 4 weeks. The acitivity patterns did not parallel those of taurine excretion or conjugation observed previously among rats fed the same diets, and may indicate that factors other than taurine synthesis and ingestion control those processes.     

Dietary effect of omega-3 type polyunsaturated fatty acids on serum and liver lipid levels in rats

The dietary effect of omega-3 type highly polyunsaturated fatty acid concentrate (PUFA mix) was investigated on cholesterol and triglyceride levels in the serum and liver, and high density lipoprotein cholesterol (HDL-cholesterol) levels in the serum. The PUFA mix prepared from squid liver oil contained about 75% of total omega-3 type fatty acids. In rats fed the normal diet to which 3% PUFA mix was added, the levels of triglyceride, total cholesterol and phospholipid in the serum markedly decreased as compared to rats fed a 3% methyl-oleate diet. However, lipid peroxide values in the liver and serum increased in rats fed PUFA mix-diets. In the hypercholesterolemic rats, a 5% PUFA mix-diet caused growth retardation and a corresponding reduction in food intake. Lipid peroxide in the liver and serum were more elevated in rats fed diets containing 1, 3 and 5% PUFA mix than in rats fed diets containing 5% oleate or 5% linoleate. In all the rats on PUFA mix-diets, there were depression of serum total cholesterol and elevation of serum HDL-cholesterol. The ratio of HDL-cholesterol to total cholesterol increased in proportion to the amounts of dietary PUFA mix. Total cholesterol level in the liver was depressed after PUFA mix feeding.     

Alterations in the blood glucose, serum lipids and renal oxidative stress in diabetic rats by supplementation of onion (Allium cepa. Linn)

This study examined the anti-diabetic effect of onion (Allium cepa. Linn) in the streptozotocin (STZ)-induced diabetic rats. Male Sprague-Dawley rats were divided into normal rats fed control diet or supplemented with onion powder (7% w/w) and diabetic rats fed control diet or supplemented with onion powder. Diabetes was induced by a single injection of STZ (60 mg/kg, ip) in citrate buffer. The animals were fed each of the experimental diet for 5 weeks. Blood glucose levels of rats supplemented with onion were lower than those of rats fed control diet in the diabetic rats. Onion also decreased the total serum lipid, triglyceride, and atherogenic index and increased HDL-cholesterol/total cholesterol ratio in the diabetic rats. Glutathione peroxidase, glutathione reductase and glutathione S-transferase activities were high in the diabetic rats compared to normal rats and reverted to near-control values by onion. These results indicate that onion decreased blood glucose, serum lipid levels and reduced renal oxidative stress in STZ-induced diabetic rats and this effect might exert the anti-diabetic effect of onion.