Taurine alters respiratory gas exchange and nutrient metabolism in type 2 diabetic rats

OBJECTIVE: To assess the effect of taurine supplementation on respiratory gas exchange, which might reflect the improved metabolism of glucose and/or lipid in the type 2 diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats. RESEARCH METHODS AND PROCEDURES: Male OLETF rats (16 weeks of age) were randomly divided into two groups: unsupplemented group and taurine-supplemented (3% in drinking water) group. After 9 weeks of treatment, indirect calorimetry and insulin tolerance tests were conducted. The amounts of visceral fat pads, tissue glycogen, the blood concentrations of glucose, triacylglycerol, taurine, and electrolytes, and the level of hematocrit were compared between groups. A nondiabetic rat strain (Long-Evans Tokushima Otsuka) was used as the age-matched normal control. RESULTS: The indirect calorimetry showed that the treatment of OLETF rats with taurine could reduce a part of postprandial glucose oxidation possibly responsible for the increase of triacylglycerol synthesis in the body. Taurine supplementation also improved hyperglycemia and insulin resistance and increased muscle glycogen content in the OLETF rats. Supplementation with taurine increased the blood concentration of taurine and electrolyte and fluid volume, all of which were considered to be related to the improvement of metabolic disturbance in OLETF rats. DISCUSSION: Taurine supplementation may be an effective treatment for glucose intolerance and fat/lipid accumulation observed in type 2 diabetes associated with obesity. These metabolic changes might be ascribed, in part, to the alteration of circulating blood profiles, where the improved hyperglycemia and/or the blood accumulation of taurine itself would play roles.     

Decreased blood levels of lactic acid and urinary excretion of 3-methylhistidine after exercise by chronic taurine treatment in rats

Taurine is reported to increase contractility of skeletal muscle and cardiac myocyte, which can increase exercise performance. The present study aimed to clarify taurine's effect on chronic endurance exercise, especially accumulation of lactic acid (LA), a marker of fatigue and ability of aerobic exercise, and urinary secretion of 3-methylhistidine (3-MH), a marker of muscle breakdown in rats. After exercise blood levels of LA and urinary excretion of 3-MH were significantly increased and this increase was significantly less in those with chronic treatment of taurine. Taurine treatment also significantly decreased fat accumulation and blood levels of cholesterol and triglyceride, which might improve insulin resistance and utilization of fat and glucose. These results indicate taurine treatment is useful for reducing physical fatigue and muscle damage during exercise training in rats, presumably due to antioxidant property and improvement of muscle and cardiac functions by taurine.     

牛磺酸对幼鼠脑神经保护作用和机制研究

目的　观察牛磺酸 (Tau)对幼鼠脑神经的保护作用 ,并对其可能机制进行探讨。方法　用 0 .1 μmol/L亚硒酸钠与不同浓度的 Tau共同加入到原代培养 2 d的新生小鼠大脑皮质神经元中 ,用 MTT检测和 DNA片段琼脂糖凝胶电泳法分析其保护性作用 ;并选用健康清洁级、断乳SD雌鼠 3 2只 ,按体重随机分为 4组 ,分别饲予补充不同水平 Tau的实验饲料 ,观察对照组及补充Tau组幼鼠脑发育及代谢的影响。结果　 1 .Tau可明显提高神经元的存活率 ;2 .一定浓度的 Tau可阻断或部分阻断由亚硒酸钠诱导的典型 DNA梯型 ;3 .Tau可促进脑细胞的增殖活性 ,增加脑重 ;4.补充 Tau能明显提高脑 Tau积累、蛋白质和 ACh E水平 ,且有一定的剂量反应关系。结论　补充 Tau具有较强的神经保护作用 ,可能是通过改变某些蛋白质即某些基因的表达而实现的。     

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.     

Antihyperglycemic effect of stem bark powder from paper mulberry (Broussonetia kazinoki Sieb.) in type 2 diabetic Otsuka Long-Evans Tokushima fatty rats

The effect of stem bark powder from paper mulberry (PMSB) on serum glucose, insulin, fructosamine, and lipid concentrations, as well as enzyme activities that serve as liver injury markers, was investigated in genetically diabetic Otsuka Long-Evans Tokushima fatty (OLETF) rats. Both nondiabetic Long-Evans Tokushima Otsuka (LETO) rats and diabetic OLETF rats (30 weeks old) were fed a semisynthetic diet with or without 50 g/kg PMSB for 8 weeks and then compared. The OLETF control rats showed a high amount of daily water intake in comparison to those in the LETO group. The concentrations of glucose, fructosamine, total lipid, triglyceride, total cholesterol, and high-density lipoprotein-cholesterol and the activities of aspartate aminotransferase and alanine aminotransferase (ALT) in serum were higher in the OLETF control rats than those in the LETO control rats. However, PMSB ingestion decreased the serum levels of glucose, fructosamine, triglyceride, and total cholesterol and the activity of ALT in the OLETF rats, but not in the LETO rats. The concentration of serum insulin was also significantly increased by PMSB consumption in the OLETF rats compared to the OLETF control rats. These results suggest that PMSB might have an antihyperglycemic effect in the OLETF rat and that the increased blood insulin level would be an important regulatory factor for improving hyperglycemia in the current animal model.     

Stimulation of chenodeoxycholic acid excretion in hypercholesterolemic mice by dietary taurine

The effects of dietary taurine on fecal steroid excretion and bile acid pool size were investigated in Jcl: ICR strain mice. The mice were fed on semi-purified diets for five weeks: 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 (C-CA + 5% taurine). The changes in fecal steroid excretion were studied as a function of time and the bile acid pool size was estimated. Dietary taurine affected fecal bile acid excretion both quantitatively and qualitatively. No change in bile acid pool size was observed. The fecal excretion of bile acids increased in taurine-supplemented mice. The increase in the fecal neutral steroid excretion was less than that in C-CA fed mice. The proportion of chenodeoxycholic acid (CDCA) and the related bile acids to total bile acids increased both in the fecal bile acids and in the bile acid pool. Therefore, the protective effect of dietary taurine against cholesterol gallstone formation may be related to the stimulation of bile acid synthesis, especially of CDCA and related compounds.     

The 10trans, 12cis isomer of conjugated linoleic acid promotes energy metabolism in OLETF rats

OBJECTIVE: We investigated the effect of conjugated linoleic acid (CLA) on energy metabolism in Otsuka Long-Evans Tokushima Fatty (OLETF) rats. METHODS: In experiment 1, male OLETF rats were fed either control diet, 10% safflower oil or CLA diet, 9% safflower oil plus 1% CLA for 4 wk. In experiment 2, male OLETF rats were fed either 9c,11t-CLA diet, 9% safflower oil plus 1% 9c,11t-CLA-rich oil or 10t,12c-CLA diet, 9% safflower oil plus 1% 10t,12c-CLA-rich oil for 10 d. RESULTS: In experiment 1, after 4 wk of feeding, serum and hepatic triacylglycerol concentrations in the CLA group were decreased significantly as compared with the control group. The CLA diet increased oxygen consumption and energy expenditure as compared with the control diet in OLETF rats. In experiment 2, a significant reduction of serum and hepatic triacylglycerol concentrations was seen in the 10t,12c-CLA group as opposed to the 9c,11t-CLA group. Oxygen consumption and energy expenditure were significantly higher in the 10t,12c-CLA group than in the 9c,11t-CLA group. CONCLUSIONS: These results demonstrated that the hypolipidemic effect and the enhancement of energy metabolism by CLA can be attributed to the effect of the 10t,12c-CLA isomer.     

S-adenosyl-L-methionine increases skeletal muscle mitochondrial DNA density and whole body insulin sensitivity in OLETF rats

Both mitochondrial dysfunction and alterations in mitochondrial DNA (mtDNA) are implicated in type 2 diabetes mellitus and insulin resistance. Evidence also suggests that metabolism of S-adenosyl-L-methionine (SAM), the universal methyl donor for biological methylation, is associated with mitochondrial dysfunction and insulin resistance. We investigated the effect of SAM on mtDNA density and insulin sensitivity using the Otsuka Long-Evans Tokushima Fatty (OLETF) rat, an animal model of type 2 diabetes mellitus and insulin resistance. To determine the short-term effect on mtDNA density, SAM (15 mg.kg-1.d-1) was administered intraperitoneally for 7 d to 6 male, 57-wk-old OLETF rats and 6 Long-Evans Tokushima Otsuka (LETO) rats of the same age as a nondiabetic control. To determine the long-term effect, the same dose of SAM was administered daily to 5 male, 6-wk-old OLETF rats until the age of 25 wk; 7 control OLETF rats received vehicle and 7 LETO rats were untreated. Skeletal muscle mtDNA density was measured by either competitive or multiplex PCR and insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp. SAM treatment for 1 wk increased skeletal muscle mtDNA density of both OLETF and LETO rats. The long-term SAM treatment significantly reduced body weight gain as well as increased skeletal muscle mtDNA density and whole body insulin sensitivity in OLETF rats compared with their vehicle-treated controls. Furthermore, in all 3 groups, skeletal muscle mtDNA density correlated with insulin sensitivity (r=0.752, P<0.001). In conclusion, SAM treatment increased mtDNA density in the skeletal muscle, improved whole body insulin sensitivity, and prevented body weight gain in OLETF rats.     

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.     

Effect of taurine on total parenteral nutrition-associated cholestasis

A decrease in the formation/secretion of bile has been well documented in animals on total parenteral nutrition (TPN). Either an excess or an imbalance of amino acids (AA) has been most often implicated. In view of recent work showing that taurine promotes bile flow, bile acid secretion, and protects against hepatotoxic bile acids, the effect of adding taurine (15 mg/dL) to an AA solution was examined in guinea pigs on TPN for 3 days. The TPN-taurine group had a larger bile flow than the group without taurine and had bile acid secretory rates (BASR) similar to those of controls who were on saline by central catheter and had free access to food. Bile composition showed an increase in the secondary bile acid, 7-ketolithocholate and a concomitant decrease in chenodeoxycholate (CDC) in both experimental groups. Taurine led to a reversal of the usual predominance of glycine over taurine conjugated bile acids as well as to increases in HCO3 in cholesterol secretion. In response to a challenge with a large load of CDC, the TPN-taurine animals increased their BASR beyond those observed in the two other groups. These observations suggest that the addition of taurine to TPN solutions could play a role in the prevention of altered biliary function associated with AA solutions.     

Taurine prevents hypercholesterolemia in ovariectomized rats fed corn oil but not in those fed coconut oil

We studied whether the type of dietary fatty acid influences the preventive effect of taurine on the ovarian hormone deficiency-induced increase in plasma cholesterol concentration in 6-mo-old ovariectomized rats. Rats were fed one of the following four diets for 28 d: purified diets based on corn oil, which is rich in linoleic acid, with or with out taurine (50 g/kg) or purified diets based on coconut oil, which is rich in lauric and myristic acids, with or without taurine. Body mass gain, food intake, liver weight and plasma apolipoprotein (apo) A-I, apo B, LDL and VLDL concentrations were not affected by the diets. On the other hand, taurine lowered the plasma total cholesterol concentration (P < 0.02) in rats fed corn oil, but not in those fed coconut oil. In rats fed both types of oils, taurine increased the LDL receptor mRNA level (P < 0.01), hepatic cholesterol 7alpha-hydroxylase activity (P < 0.01) and fecal bile acid excretion (P < 0.01). Taurine increased the HMG-CoA reductase mRNA level (P < 0.02) in the liver of rats fed coconut oil, but not in those fed corn oil. Taurine increased liver total lipid (P < 0.05) and triglyceride (P < 0.05) concentrations in rats fed corn oil, but not in those fed coconut oil. These results indicate that the effect of taurine on ovarian hormone deficiency-induced changes in cholesterol metabolism is influenced by the type of dietary fatty acids.     

Antidiabetic effect of probiotic dahi containing Lactobacillus acidophilus and Lactobacillus casei in high fructose fed rats

OBJECTIVE: We investigated the effect of low-fat (2.5%) dahi containing probiotic Lactobacillus acidophilus and Lactobacillus casei on progression of high fructose-induced type 2 diabetes in rats. METHODS: Diabetes was induced in male albino Wistar rats by feeding 21% fructose in water. The body weight, food and water intakes, fasting blood glucose, glycosylated hemoglobin, oral glucose tolerance test, plasma insulin, liver glycogen content, and blood lipid profile were recorded. The oxidative status in terms of thiobarbituric acid-reactive substances and reduced glutathione contents in liver and pancreatic tissues were also measured. RESULTS: Values for blood glucose, glycosylated hemoglobin, glucose intolerance, plasma insulin, liver glycogen, plasma total cholesterol, triacylglycerol, low-density lipoprotein cholesterol, very low-density lipoprotein cholesterol, and blood free fatty acids were increased significantly after 8 wk of high fructose feeding; however, the dahi-supplemented diet restricted the elevation of these parameters in comparison with the high fructose-fed control group. In contrast, high-density lipoprotein cholesterol decreased slightly and was retained in the dahi-fed group. The dahi-fed group also exhibited lower values of thiobarbituric acid-reactive substances and higher values of reduced glutathione in liver and pancreatic tissues compared with the high fructose-fed control group. CONCLUSION: The probiotic dahi-supplemented diet significantly delayed the onset of glucose intolerance, hyperglycemia, hyperinsulinemia, dyslipidemia, and oxidative stress in high fructose-induced diabetic rats, indicating a lower risk of diabetes and its complications.     

Taurine modulates platelet aggregation in cats and humans

To explore the relationship between whole-body taurine status and function, the taurine concentration in plasma and platelets was measured and evaluated in terms of ex vivo collagen-induced platelet aggregation in taurine-depleted cats and taurine-supplemented humans. Taurine status exerted a significant effect on platelet aggregability. Platelets from taurine-depleted cats were twice as sensitive to aggregation as platelets from cats receiving taurine. On the other hand, platelets from humans with normal taurine status increased resistance to aggregation by 30-70% when supplemented with taurine at 400 or 1600 mg/d, respectively. Decreased platelet aggregability was associated with increased platelet taurine and glutathione concentrations and decreased thromboxane release on aggregation. These data indicate that taurine in vivo stabilizes platelets against aggregation such that during taurine depletion platelets become overly sensitive whereas during supplementation their tendency to aggregate is depressed.     

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.     

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.     

The effect of taurine on plasma cholesterol concentration in genetic type 2 diabetic GK rats

The purpose of this study is to investigate the effect of taurine on the plasma cholesterol concentration in genetic type 2 diabetic rats fed cholesterol-free or high-cholesterol diets. Diabetic rats (GK male rats) and normal rats (Wistar male rats) were fed either a cholesterol-free or cholesterol-enriched (1% cholesterol + 0.25% sodium cholate) diet supplemented with or without 3% taurine for 21 or 14 d. Compared to the normal rats, diabetic rats showed a high glucose concentration in their blood and plasma, but it was not affected by taurine feeding. The plasma insulin concentration was higher in the diabetic rats than in the normal rats. At the start of the experiment, the plasma cholesterol concentration was significantly higher in the diabetic rats than in the normal rats. Taurine did not affect the plasma cholesterol level in rats fed the cholesterol-free diet. However, taurine feeding significantly increased the plasma HDL-cholesterol concentration in the diabetic rats fed the cholesterol-free diet. In both the diabetic and normal rats fed the cholesterol diet, the plasma cholesterol concentration was significantly lower in rats fed the diet supplemented with taurine than in the rats fed the control diet. It was concluded that taurine has a hypocholesterolemic effect in both diabetic and normal rats fed diets containing cholesterol. Moreover, these results suggest that taurine seems to affect the HDL-cholesterol metabolism in diabetic rats fed a cholesterol-free diet.     

Effect of a low protein diet on bile flow and composition in rats

The effect of feeding a low protein (LP) diet on bile flow and biliary lipid and protein secretion was studied with young female rats. Animals fed a 8% protein diet (LP) for 4, 8 and 12 wk had a significantly lower bile flow and a lower biliary bile acid and protein secretion rate compared with rats fed a 26% protein (normal) diet (NP). The bile acid-independent fraction of bile flow was significantly increased. The slope of the regression line to zero bile acid was markedly smaller in the LP than in the NP group, indicating lower bile acid-dependent bile flow. Biliary phospholipid and cholesterol secretion rates were significantly higher in the LP than in the NP group, demonstrating an uncoupling between bile acid and lipid secretion at the low rates of bile acid secretion. The percentage increase for these parameters was of similar magnitude (30%). Absolute concentrations of bile acid, phospholipid and cholesterol were significantly higher in LP-fed rats than in NP rats, while relative concentration of bile acid was lower and those of cholesterol and phospholipid were higher. Analysis of biliary bile acids showed that the percent contribution of chenodeoxycholic acid and of deoxycholic acid increased significantly in the LP-fed rats, while that of cholic acid decreased. These data indicate that the lower bile flow in the rats fed LP can be attributed to lower bile salt-dependent flow associated with significantly lower choleretic potency of bile acids secreted.     

Muscle lipid metabolism and insulin secretion are altered in insulin-resistant rats fed a high sucrose diet

Feeding rats a sucrose rich diet (SRD) induces hypertriglyceridemia and insulin resistance. The purposes of this study were to determine the time course of changes in lipid and glucose metabolism in the gastrocnemius muscle, both in the basal state and after the euglycemic hyperinsulinemic clamp, in rats fed a SRD for 3, 15 or 30 wk, and to analyze the changes in glucose-stimulated insulin secretion from perifused isolated islets from SRD-fed rats and their relationships to peripheral insulin insensitivity. A control group of rats was fed a control diet (CD) for the same period of time. After 3 wk of consuming the SRD, long-chain acyl CoA (LCACoA) levels in muscle were greater than in rats fed the CD, an early indication of the disturbance of lipid metabolism. Neither glycogen storage nor glucose oxidation were impaired at this time. Moreover, the biphasic patterns of glucose-stimulated insulin secretion showed a marked increase in the first peak, which helped maintain normoglycemia in SRD-fed rats. After 15 or 30 wk of consuming the SRD, triglyceride and LCACoA levels in muscles were greater than in rats fed the CD. Glucose oxidation as well as insulin-stimulated glycogen synthase activity and glycogen storage were lower than in rats fed the CD. Moreover, the altered pattern of insulin secretion further deteriorated. This was accompanied by peripheral insulin resistance and moderate hyperglycemia. Our results indicate that the dyslipemia present in rats chronically fed a SRD may play an important role in the progressive deterioration of insulin secretion and sensitivity in this animal model.     

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.