Kyung Ja Chang

The Effect of Dietary Taurine Supplementation on Plasma and Liver Lipid Concentrations and Free Amino Acid Concentrations in Rats Fed a High-Cholesterol Diet

The purpose of this study was to investigate the effect of dietary taurine supplementation on plasma and liver lipid concentrations, and free amino acid concentrations in rats fed a high-cholesterol diet. Twenty male rats (body weight 151 +/- 1.9 g) were randomly divided into two groups. The rats in the control group were fed on 1.5% cholesterol diet (control) and those in the experimental group were fed with 1.5% cholesterol and 1.5% taurine diet (TSD). All rats were fed with the experimental diets and deionized water ad libitum for 5 weeks. The plasma glucose and lipid concentrations were measured using commercial kits with enzymatic methods and liver lipid concentrations with the Folch method. The concentrations of free amino acids in plasma were determined with an automated amino acid analyzer based on ion-exchange chromatography. There were no significant differences in the body weight gain, food intake and food efficiency ratio between the control and experimental groups. The rats fed TSD had significantly lower liver weight and liver weight/body weight ratio than those fed control diet. The plasma concentrations of total cholesterol, glucose and LDL-cholesterol were significantly reduced in the rats fed TSD compared to those fed control diet. The rats fed TSD showed significantly decreased liver levels of cholesterol and triglyceride. The HDL-cholesterol level was higher in the rats fed TSD than those fed control diet. The plasma taurine concentrations were not significantly different between two groups. They exhibited significant negative correlation with the plasma total cholesterol and liver triglyceride concentrations. These results suggest the possible role of taurine as a hypocholesterolemic agent in the rats fed a high cholesterol diet. Taurine supplementation did not cause any characteristic changes in the plasma aminogram pattern, body weight gain, and food intake.

Effects of taurine supplementation on lipid peroxidation, blood glucose and blood lipid metabolism in streptozotocin-induced diabetic rats.

The purpose of this study was to determine the effect of taurine on several complications of diabetes, including oxidative stress, glucose intolerance and blood lipid profile. Sprague Dawley male rats were fed an experimental diet for 7 weeks, at which time they were maintained on drinking water with or without 1% taurine. The experimental period was 7 weeks and the rats were administered streptozotocin (STZ) to induce diabetes. Thiobarbituric acid reactive substances (TBARS) content was increased following the STZ injection, but was lowered by prior treatment with taurine. The primary diabetic symptoms, such as polydipsia and polyuria, were ameliorated in rats supplemented with taurine before the STZ injection. Plasma triglyceride (TG) levels of the diabetic group were decreased by taurine supplementation, although plasma total cholesterol (T-chol) and HDL cholesterol (HDL-chol) were not different among the groups. LDL cholesterol (LDL-chol) levels of the control group were significantly decreased by taurine supplementation, however, the time of taurine administration affected the response of the diabetic group; only diabetic rats treated with taurine after the administration of STZ showed a decrease in LDL cholesterol. Therefore, taurine inhibits lipid peroxidation and decreases blood TG and LDL-chol levels, however, the time and dose of taurine supplementation are variables that need to be considered in the treatment of diabetes.

Taurine Protects the Liver against Lipid Peroxidation and Membrane Disintegration during Rat Hepatocarcinogenesis

The purpose of this study was to determine the effects of taurine supplementation on both hepatic morphological changes and the extent of hepatic lipid peroxidation and membrane disintegration during rat hepatocarcinogenesis. Sprague Dawley rats were fed high fat diets containing 15% corn oil and were maintained on drinking water with or without 1% taurine. Two weeks after the appropriate feeding regimen, hepatocarcinogenesis was induced by a modification of the Solt and Farber method. This involved a 8 week protocol, including diethylnitrosamine initiation, 3 weeks of 2-acetylaminofluorene feeding and finally a 70% partial hepatectomy. Morphological changes of the hepatocyte were observed by transmission electron microscopy (TEM). Hepatocytes of the carcinogen-treated rat not exposed to taurine contained normal nuclei, but the endoplasmic reticulum (ER) and the mitochondria (Mi) were almost destroyed. By contrast, although the hepatocytes from the taurine supplemented group contained some irregular contour nuclei, the ER and Mi were normal. In the carcinogen-treated groups, lipid peroxidation was decreased because of the activation of several detoxifying enzymes. Glutathione S-transferase (GST) activity increased in the carcinogen-treated groups but less so in the group supplemented with taurine before treatment with the carcinogen. In the group supplemented with taurine prior to treatment with the carcinogen, glutathione peroxidase (GPx) activity was higher than in the carcinogen-treated group lacking taurine exposure. Consistent with the severe destruction to the membrane in the carcinogen-treated rats, hepatic glucose-6-phosphatase (G6Pase) activity, an index of membrane stability, was also decreased. However, both the fall in G6Pase activity and the degree of membrane damage was reduced in the carcinogen-treated animals receiving oral taurine. These results suggest that taurine appears to inhibit lipid peroxidation, to alter the activity of the defense enzymes and to protect the liver against membrane disintegration during rat hepatocarcinogenesis.

Taurine ameliorates hyperglycemia and dyslipidemia by reducing insulin resistance and leptin level in Otsuka Long-Evans Tokushima fatty (OLETF) rats with long-term diabetes

This study aimed to determine whether taurine supplementation improves metabolic disturbances and diabetic complications in an animal model for type 2 diabetes. We investigated whether taurine has therapeutic effects on glucose metabolism, lipid metabolism, and diabetic complications in Otsuka Long-Evans Tokushima fatty (OLETF) rats with long-term duration of diabetes. Fourteen 50-week-old OLETF rats with chronic diabetes were fed a diet supplemented with taurine (2%) or a non-supplemented control diet for 12 weeks. Taurine reduced blood glucose levels over 12 weeks, and improved OGTT outcomes at 6 weeks after taurine supplementation, in OLETF rats. Taurine significantly reduced insulin resistance but did not improve β-cell function or islet mass. After 12 weeks, taurine significantly decreased serum levels of lipids such as triglyceride, cholesterol, high density lipoprotein cholesterol, and low density lipoprotein cholesterol. Taurine significantly reduced serum leptin, but not adiponectin levels. However, taurine had no therapeutic effect on damaged tissues. Taurine ameliorated hyperglycemia and dyslipidemia, at least in part, by improving insulin sensitivity and leptin modulation in OLETF rats with long-term diabetes. Additional study is needed to investigate whether taurine has the same beneficial effects in human diabetic patients.

Ethanol extract of lotus (Nelumbo nucifera) root exhibits an anti-adipogenic effect in human pre-adipocytes and anti-obesity and anti-oxidant effects in rats fed a high-fat diet

Lotus (Nelumbo Nucifera) root, a well-known medicinal plant in Asia, is reported to have various therapeutic benefits, including anti-diabetes, anti-hypertension, and anti-hyperlipidaemia. We hypothesized that the ethanol extract of lotus root (ELR) would exhibit an anti-adipogenic effect in human pre-adipocytes as well as anti-obesity and anti-oxidant effects in rats fed a high-fat diet. Treatment with ELR in human pre-adipocytes resulted in inhibition of lipid accumulation and attenuated expression of adipogenic transcription factors such as peroxisome proliferator-activated receptor gamma and adipocyte marker genes, such as glucose transporter 4 and leptin. Administration of ELR resulted in a significant decrease in relative weights of adipose tissues in rats fed a high-fat diet. Consumption of a high-fat diet resulted in an increase in serum total cholesterol (TC) and triglyceride (TG) levels; however, administration of ELR resulted in a decrease in the levels of TC and TG. Administration of ELR resulted in a decrease in the level of serum leptin and insulin. Administration of ELR in rats fed a high-fat diet resulted in a decrease in hepatic thiobarbituric acid reactive substance content, elevated by a high-fat diet and an increase in superoxide dismutase activity and hepatic glutathione content. These results suggest that lotus root exerts anti-oxidant and anti-obesity effects and could be used as a functional and nutraceutical ingredient in combatting obesity-related diseases.

Immunohistochemical Localization of Insulin in Pancreatic β-Cells of Taurine-Supplemented or Taurine-Depleted Diabetic Rats

The purpose of this study was to observe the effects of taurine supplementation or depletion on the immunohistochemical localization of insulin in pancreas of streptozotocin-induced diabetic rats. Male Sprague-Dawley rats were fed for 7 weeks with a purified diet that was supplemented with 0, 1, 2 or 3% taurine in their drinking water. To induce taurine depletion, rats were treated with 5% beta-alanine in their drinking water. After 3 weeks, diabetes was induced by streptozotocin injection (50 mg/kg body-weight). The pancreatic tissue was stained immunocytochemically, using an antibody to insulin, and examined by light microscopy. The insulin levels in pancreatic beta-cells of the diabetic group that received no taurine-supplement were significantly decreased, compared to the non-diabetic group. The levels of insulin in beta-cell of 1% and 2% taurine-supplemented diabetic groups were significantly higher than those of the diabetic group, whereas the levels in the group receiving 3% taurine were not significantly different from that of non-diabetic rats. Therefore, it may be suggested that taurine protect pancreatic beta-cells against destruction by ptozotocin injection in a dose-dependent way.

Anti-obesity and hypolipidaemic effects of Nelumbo nucifera seed ethanol extract in human pre-adipocytes and rats fed a high-fat diet.

BACKGROUND We conducted this investigation in order to examine the anti-obesity and hypolipidaemic effects of Nelumbo nucifera seed ethanol extract (NSEE) in vitro and in vivo. METHODS To study the anti-obesity effect of NSEE in vitro and in vivo, human pre-adipocytes were treated with NSEE, and male Sprague-Dawley rats were fed with a normal diet and a high-fat diet with or without NSEE, respectively. RESULTS In vitro treatment with NSEE resulted in inhibition of lipid accumulation and decreased expression of peroxisome proliferator-activated receptor gamma (PPARγ), glucose transporter 4 (GLUT4), and leptin in cultured human adipocytes, indicating that it inhibited the differentiation of pre-adipocytes into adipocytes. Administration of NSEE resulted in significantly reduced body weight gain and adipose tissue weights in rats. Serum triglyceride and leptin level of the high-fat diet + NSEE group was significantly lower, compared to the high-fat group. CONCLUSION These results demonstrate an inhibitory effect of NSEE on adipogenesis. In addition, NSEE had a beneficial effect, reducing adipose tissue weights, ameliorating blood lipid profile, and modulating serum leptin level in rats fed a high-fat diet. Therefore, we suggest that lotus seed has a potential to be developed as an effective agent against obesity-related diseases.

Effect of Taurine and β-Alanine on Morphological Changes of Pancreas in Streptozotocin-Induced Rats

In order to determine the effects of taurine supplementation or depletion on the morphological changes of pancreatic beta-cells in streptozotocin-induced diabetic rats, Sprague-Dawley male rats were fed the purified diets supplemented with 1, 2 or 3% taurine or 5% beta-alanine in their drinking water for 7 weeks. After 3 weeks, diabetes was induced by streptozotocin injection (50 mg/kg body-weight). Pancreatic morphology was observed by transmission electron microscopy. The pancreatic beta-cell of the non-diabetic (CO) group had the many secretory granules, rough endoplasmic reticulum and rod shaped mitochondria. However, the beta-cells of non taurine-supplemented diabetic (EO) group were severely damaged, showing depleted secretory granules. In the 1% taurine-supplemented diabetic group, the beta-cells were less damaged compared to the EO group and had some apparently normal secretory granules, but most of rough endoplasmic reticulum and mitochondria was destroyed. The beta-cell of 2% taurine-supplemented diabetic group had swollen rough endoplasmic reticulum, round-shaped mitochondria and some apparently normal secretory granules. The beta-cell of 3% taurine-supplemented diabetic group was little different from that of non-diabetic group. The pancreatic beta-cell of taurine-depleted diabetic group was not destroyed but had many small secretory granules which appeared immature. This was reflected in the blood glucose concentrations of this group. Therefore, taurine may prevent insulin-dependent diabetes by protection of the pancreatic beta-cell and may also preserve normal secretory granules. From these results, taurine supplementation may be recommended for prevention and treatment of diabetes.

Comparative Analysis of Antioxidant Activity and Functional Components of the Ethanol Extract of Lotus (Nelumbo nucifera) from Various Growing Regions

The variations in antioxidant activity and concentration of functional components in the ethanol extracts of lotus seeds and rhizomes based on the growing region and dryness were investigated. Free radical scavenging activity, total phenolic and flavonoid content, and concentration of several specific flavonoids and alkaloids in the ethanol extracts of lotus were measured. Antioxidant activity and its correlative total phenolic content varied characteristically depending on the growing region and dryness. High-perfomance liquid chromatography analysis showed that the ethanol extracts of lotus seeds from Vietnam (Ho Chi Minh City), raw rhizomes from Korea (Siheung), and dried rhizomes from Japan (Nigata) had the greatest specific flavonoid content. The ethanol extracts of seeds from China (Hubei), raw rhizomes from Japan (Nigata), and dried rhizomes from Korea (Siheung) had the greatest specific alkaloid content. Astragaline, rutin, isoquercetin, nuciferine, dauricine, isoliensinine, and neferine were identified in lotus rhizomes for the first time in this study.

Serum osteopontin concentration is decreased by exercise-induced fat loss but is not correlated with body fat percentage in obese humans.

To evaluate the extent to which fat mass contributes to serum osteopontin (OPN) concentration, we investigated whether serum OPN levels are decreased by exercise-induced fat mass loss and whether they are associated with body fat percentage in obese humans. Twenty‑three female college students were recruited to participate in an 8‑week body weight control program. Body composition [body weight, soft lean mass, body fat mass, body fat percentage, waist-hip ratio and body mass index (BMI)] were assessed prior to and following the program. Serum lipid profiles and serum adiponectin, leptin and osteopontin levels were measured from serum collected prior to and following the program. To understand the effect of fat mass loss on the serum levels of adipokine, which is mainly produced in adipose tissue, the leptin and adiponectin levels were also measured prior to and following the program. Serum leptin levels (mean ± standard error of the mean) decreased significantly following the program (from 9.82±0.98 to 7.23±0.67 ng/ml) and were closely correlated with body fat percentage. In addition, serum adiponectin levels were negatively correlated with body fat percentage, while serum adiponectin levels were not significantly altered. By contrast, serum OPN levels decreased significantly following the program (from 16.03±2.34 to 10.65±1.22 ng/ml). However, serum OPN levels were not correlated with body fat percentage, suggesting that serum OPN levels are controlled by several other factors in humans. In conclusion, a high expression of OPN in adipose tissues may not be correlated with serum OPN levels in obese humans. Thus, tissues or physiological factors other than fat mass may have a greater contribution to the serum OPN levels.