Role of taurine supplementation to prevent exercise-induced oxidative stress in healthy young men

Summary. To evaluate the protective effects of taurine supplementation on exercise-induced oxidative stress and exercise performance, eleven men aged 18–20 years were selected to participate in two identical bicycle ergometer exercises until exhaustion. Single cell gel assay (SCG assay) was used to study DNA damage in white blood cells (WBC). Pre-supplementation of taurine, a significant negative correlation was found between plasma taurine concentration before exercise and plasma thiobaribituric-acid reactive substance (TBARS) 6hr after exercise (r=–0.642, p<0.05). WBC showed a significant increase in DNA strand breakage 6hr and 24hr after exercise. Seven-day taurine supplementation reduced serum TBARS before exercise (p<0.05) and resulted in a significantly reduced DNA migration 24hr after exercise (p<0.01). Significant increases were also found in VO₂max, exercise time to exhaustion and maximal workload in test with taurine supplementation (p<0.05). After supplementation, the change in taurine concentration showed positive correlations with the changes in exercise time to exhaustion and maximal workload. The results suggest that taurine may attenuate exercise-induced DNA damage and enhance the capacity of exercise due to its cellular protective properties.     

Long-term taurine supplementation reduces mortality rate in streptozotocin-induced diabetic rats

Summary. Oxidative stress is implicated in the pathogenesis of diabetes mellitus. Taurine and vitamin E+selenium supplementation has some benefits in experimental models of diabetes mellitus. This study evaluates whether taurine and vitamin E+selenium supplementations reduce a hard end-point such as mortality due to diabetes. Streptozotocin-induced diabetic rats were fed with standard diet or taurine (5%, w/w) or vitamin E (500UI/Kg)+selenium (8mg/Kg) enriched diets. Taurine significantly decreased mortality rate (p<0.04), while vitamin E failed to increase survival. In the late phase of the disease, taurine significantly decreased glycaemia, being vitamin E ineffective. No correlation between glycaemia and survival was found. None of supplementations modified body weight. Thus, only taurine decreases the mortality rate and glycaemia. These results encourage new research in the field, since classical hypoglycaemic agents are unable to decrease mortality in diabetic patients.     

Pattern visual evoked potentials in the early diagnosis of optic neuropathy in the course of Graves' ophthalmopathy

THE AIM OF THE STUDY: To investigate by means of pattern visual evoked potentials (PVEPs) early neuropathic changes in Graves' ophthalmopathy (GO) patients without any clinical symptoms of optic neuropathy in order to evaluate the prevalence of subclinical optic neuropathy in GO patients and to elucidate whether there is a relationship between PVEP (P100 and N75 latency), intraocular pressure (IOP) and exophthalmometry. MATERIAL AND METHODS: Two groups of patients were examined: 15 patients with GO without clinical signs of dysthyroid optic neuropathy (DON) and 12 healthy controls. The correlations between the N75 and P100 latencies, IOP and Hertel exophthalmometry were investigated. RESULTS: The mean PVEP N75 and P100 latencies were significantly delayed in the GO uncomplicated with DON in comparison with controls (LP100- 106.2 +/- 4.4 ms vs. 102.4 +/- 2.7 ms, p < 0.01 and LN75- 79.0 +/- 3.7 ms vs. 73.9 +/- 2.8 ms, p < 0.001). In GO patients we documented a positive correlation between the LN75 latency and exophthalmometric readings (R = 0.51; p < 0.01). The value of LP100 and LN75 was above the normal limit in 5/30 eyes (17%) and in 3/30 eyes (10%) respectively. CONCLUSIONS: The assessment of PVEPs (especially the P100 latency) in GO patients without clinical signs of DON is a useful tool for the early diagnosis of optic nerve involvement.     

Beneficial effects of taurine on serum lipids in overweight or obese non-diabetic subjects

Summary. Taurine has beneficial effects on lipid metabolism in experimental animals fed with high-cholesterol or high fat diets. Whether taurine benefits lipid metabolism in humans has rarely been investigated. The aim of this study was to evaluate the effects of taurine on serum lipids in overweight or obese young adults. Thirty college students (age: 20.3±1.7 years) with a body mass index (BMI) 25.0kg/m², and with no evidence of diabetes mellitus were selected and assigned to either the taurine group (n=15) or the placebo group (n=15) by double-blind randomization. Taurine 3g/day or placebo was taken orally for 7 weeks. Triacylglycerol (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and plasma glucose were measured before and after supplementation. The atherogenic index (AI) was calculated as (TC–HDL-C)/HDL-C. There were no differences in any baseline parameter between the two groups. Taurine supplementation decreased TG and AI significantly. Body weight also reduced significantly in the taurine group. These results suggest that taurine produces a beneficial effect on lipid metabolism and may have an important role in cardiovascular disease prevention in overweight or obese subjects.     

Taurine protected myocardial mitochondria injury induced by hyperhomocysteinemia in rats

Summary. Taurine can protect against cardiovascular diseases, whereas elevated levels of plasma homocysteine are associated with atherosclerotic and thromboembolic cardiovascular diseases. To illustrate the effects of taurine on hyperhomocysteinemia, we observed the myocardial mitochondria dysfunction in the rats with hyperhomocysteinemia induced by diet methionine loading, and the therapeutic effect of taurine. A methionine diet increased plasma homocysteine concentration (133.51±27.91mol/L vs 12.31±2.58mol/L in control, P<0.01), stimulated the production of reactive oxygen species (ROS) in the myocardial mitochondria, and inhibited the activities of mitochondrial Mn-superoxide dismutase and catalase. The ⁴⁵Ca uptake and Ca²⁺-ATPase activity in the myocardial mitochondria were significantly lowered in rats with hyperhomocysteinemia. Taurine supplements effectively attenuated the hyperhomocysteinemia-induced ROS production and inhibition of Mn-superoxide dismutase and catalase activities in the myocardial mitochondria, and increased its ⁴⁵Ca uptake and Ca²⁺-ATPase activity. Thus, taurine antagonizes the oxidative stress injury in the myocardial mitochondria induced by the hyperhomocysteinemia.     

Effects of taurine in glucose and taurine administration

Summary. Taurine has several biological processes such as hypoglycemic action, antioxidation, detoxification, etc. To assess the effect of taurine administration on the guinea pigs with hyperglycemia, blood glucose, C-peptide levels together with morphologic alterations in the pancreatic ultrastructure were investigated in terms of hypoglycemic action and malondialdehyde and total sulfhydryl group levels with regard to oxidation-antioxidation relation. Animals were divided into four groups of six. Glucose supplementation group was administrated a single dose of glucose (400mg/kg, i.p.) injection. Glucose and taurine supplementation group was administrated glucose treatment (a single dose, 400mg/kg, i.p.) following taurine (a single dose, 200mg/kg, i.p.). Taurine and glucose supplementation group was administered taurine treatment (a single dose, 200mg/kg, i.p.) following glucose treatment (a single dose, 400mg/kg, i.p.). Control animals received no treatment. Blood samples were collected at the end of the experiments for the determination of glucose, C-peptide (indicator of insulin secretion), lipid peroxidation (thiobarbituric acid reactive substances), and total sulfhydryl groups levels. Pancreatic tissue samples were then collected and processed for transmission electron microscopy. The findings showed that glucose supplementation following taurine administration significantly decreased blood glucose level by increasing C-peptide level and the pancreatic secretion stimulated morphologically and insignificantly changed thiobarbituric acid reactive substances and total sulfhydryl group levels. These observations suggest that taurine administration may be useful in hyperglycemia because of its hypoglycemic and protective effects.     

Dietary Taurine Supplementation Ameliorates Diabetic Retinopathy via Anti-excitotoxicity of Glutamate in Streptozotocin-induced Sprague-Dawley Rats

The purpose of this study was to investigate whether taurine ameliorate the diabetic retinopathy, and to further explore the underlying mechanisms. The Sprague-Dawley rats were injected with streptozotocin to establish experimental diabetic model, then fed without or with 1.2% taurine for additional 4–12 weeks. After that, the protective effects of dietary taurine supplementation on diabetic retinopathy were estimated. Our results showed that chronic taurine supplement effectively improved diabetic retinopathy as changes of histopathology and ultrastructure. The supplementation could not lower plasma glucose concentration (P > 0.05), but caused an elevation in taurine content and a decline in levels of glutamate and γ-aminobutyric acid (GABA) in diabetic retina (P < 0.05). Moreover, chronic taurine supplementation increased glutamate transporter (GLAST) expression (P < 0.05), decreased intermediate filament glial fibrillary acidic protein (GFAP) and N-methyl-d-aspartate receptor subunit 1 (NR1) expression in diabetic retina (P < 0.05). These results demonstrated that chronic taurine supplementation ameliorates diabetic retinopathy via anti-excitotoxicity of glutamate in rats.     

Cysteine-induced hypoglycemic brain damage: an alternative mechanism to excitotoxicity

Summary. Central neural damage caused by L-cysteine (L-Cys) was first reported more than 30 years ago. Nevertheless, the exact mechanisms of L-Cys-mediated neurotoxicity are still unclear. Preliminary study in mice demonstrated that, following L-Cys injection, animals developed tachypnea, tremor, convulsions, and death in conjunction with documented hypoglycemia. The aim of the present study was to further investigate the mechanism of L-Cys-mediated hypoglycemic effect and neural damage. Neonatal ICR mice (n=6) were injected with L-Cys (0.5–1.5mg/g body weight [BW]), and their blood glucose and insulin levels were determined up to 90min following the injection. Experiments were repeated in chemically (streptozotocin [STZ]) pancreatectomized animals. Brain histology was assessed. Mice injected with L-Cys exhibited dose-dependent neurotoxicity and higher mortality as compared with controls. L-Cys (1.2–1.5mg/g BW) caused severe hypoglycemia (glucose<42mg/dl) (P<0.001). In STZ-treated (diabetic) animals, L-Cys (1.5mg/g BW) increased plasma insulin levels 2.3-fold and decreased serum glucose levels by 50% (P<0.01). Brain histology revealed destruction of as much as 51% of hippocampal neurons in the L-Cys-treated mice but not in the glucose-resuscitated animals. These findings suggest that L-Cys injection can cause pronounced hypoglycemia and central neural damage which is glucose reversible. Since L-Cys is chemically different from the other excitatory amino acids (glutamate and aspartate), L-Cys-mediated neurotoxicity may be connected to its hypoglycemic effect.     

Plasma amino acids and sports injuries

Summary. The aim of this study was to explore the relationship between changes in plasma amino acids and the incidence of sports injuries during a soccer season. Fourteen plasma amino acids were assayed at monthly intervals in 12 young soccer players during a whole soccer season. Based on the number and severity of injuries the soccer players were divided into an injury-prone and a non-injury-prone group. The mean plasma level of the amino acid glycine was significantly lower (P=0.009) in the injury-prone group than the other group, while the mean plasma levels of tyrosine, tryptophan and lysine were higher in the injury-prone group during this period (P<0.05). However there were no significant differences in the calculated plasma tryptophan and tyrosine/large neutral amino acids ratios. Significant linear time trends were observed for taurine, ornithine, lysine and the tryptophan/large neutral amino acids ratio.These results indicate that the plasma concentrations of glycine and to a lesser extent those of tyrosine, tryptophan and lysine may be promising peripheral markers for injury-proneness in young soccer players. Whether a role for glycine substitution will be indicative to reduce the occurrence of sports injuries will need to be investigated in future studies.     

Validity of elevated interstitial levels of taurine as a predictor of myocardial ischemic injury

Summary. The microdialysis (MD) technique allows for continuous in vivo monitoring of dynamic changes in the interstitial levels of energy-related metabolites. The release of taurine from the myocyte has been suggested as a marker of ischemic injury. The relationship between (interstitial) taurine release and the degree of myocardial ischemic injury was evaluated following a 40min long ischemia in a porcine heart-infarct-model. Different protocols of ischemia and reperfusion were used in order to achieve a graded level of myocardial injury. Both interstitial peak levels and the area under curve of taurine obtained during ischemia and reperfusion correlated with the degree of ischemic injury (assessed by developed infarct size estimation). The release of taurine in the myocardium measured by the MD-technique correlated with the degree of ischemic injury during ongoing ischemic insult. Hence, taurine determination in the MD-setting represents a powerful tool to follow the development of myocardial ischemic injury over time.     

Characteristics of basal taurine release in the rat striatum measured by microdialysis

Summary. Taurine is a sulfur-containing amino acid thought to be an osmoregulator, neurotransmitter or neuromodulator in the brain. Our objective was to establish how much taurine is released in the striatum and examine the mechanisms controlling extracellular taurine concentrations under resting conditions. The experiments were made on rats by microdialysis in vivo. Changes in taurine were compared with those in glutamate, glycine and the non-neuroactive amino acid threonine. Using the zero net flux approach we showed the extracellular concentration of taurine to be 25.2±5.1M. Glutamate was increased by tetrodotoxin and decreased by Ca²⁺ omission, glycine and threonine were not affected and both treatments increased extracellular taurine. The basal taurine release was increased by the taurine transport inhibitor guanidinoethanesulfonate and reduced by the anion channel blocker 4-acetamido-4-isothiocyanatostilbene-2,2-disulfonic acid.     

The effect of taurine administration on vitamin C levels of several tissues in mice

Summary. Taurine (2-aminoethane sulphonic acid), a sulphur-containing beta amino acid, is the most prevalent free intracellular amino acid in many human and animal tissues. Vitamin C metabolism is also fluenced by sulphur-containing amino acids. The aim of this study is to investigate the effect of taurine administration on the vitamin C levels of plasma and several tissues (brain, liver, kidneys) in mice with incisional skin wounds. Animals were divided into two as control and taurine groups. Taurine was freshly dissolved in sterile saline and administered daily (60µl, ip) for five days in the taurine group. At the end of the fifth day, the animals were killed by decapitation. The brain, liver and kidneys were immediately removed. Vitamin C levels were measured in plasma and several tissues. The administration of taurine had no effect on the plasma vitamin C levels (P>0.05) but significantly increased in liver and kidneys (P<0.001). In conclusion, taurine may affect the vitamin C metabolism in tissues by different mechanisms.     

γ-氨基丁酸、荷包牡丹碱和L-谷氨酸钠对猫和家兔同侧和对侧图形视觉诱发电位的影响

在猫和家兔大脑半球一侧视区17/18交界处施加γ—氨基丁酸(GABA)、荷包牡丹碱和L—谷氨酸钠,以及用氯化钾和冷冻阻遏的方法,记录对侧和同侧皮层相应处图形视觉诱发电位(PVEP)的变化。讨论了GABA、荷包牡丹碱和L—谷氨酸钠对猫和兔的对侧和同侧PVEP的影响。     

Myocardial taurine,development and vulnerability to ischemia

Summary. Depleting intracellular taurine in heart cells improves their resistance to ischemia and reperfusion injury. The aim of this work was to see whether physiologically low levels of endogenous taurine also reflect a reduced vulnerability of the myocardium to cardiac insults. The myocardial concentration of taurine was measured during different stages of development and compared with vulnerability to ischemia and reperfusion injury in the rat and in pediatric patients undergoing cardiac surgery.Rat hearts with relatively lower levels of taurine were significantly more resistant to an ischemic inult and there was a strong negative correlation between taurine content and recovery. Childrens hearts had significantly lower taurine levels compared to infants hearts which was consistent with their known increased resistance to an ischemic cardioplegic insult (Imura et al., 2001). This work shows that the changes in the concentration of myocardial taurine during development correlate with vulnerability to ischemia where low myocardial taurine is associated with improved recovery upon reperfusion.     

Optimal and effective oral dose of taurine to prolong exercise performance in rat

Summary. The aim of this study was to determine the effective and optimum dose of taurine for exercise performance and to maintain tissue taurine concentration. Rats received a respective daily dose of 0, 20, 100, and 500mg/kg body weight of taurine (EC and ET-1, -2, -3 groups, respectively) for two weeks, and then, were subjected to treadmill until exhaustion. The running time to exhaustion was significantly prolonged by 25% and 50% in the ET-2 and -3 groups, respectively, compared to that in the EC group accompanied with maintenance of taurine tissue concentrations. Furthermore, the oxidative glutathione per total glutathione ratio in tissues was inhibited in the ET-2 and -3 groups whereas it was higher in the EC group than in both the no exercise and taurine-administered groups. Therefore the effective and optimal doses of oral taurine administration for two weeks on a transient exercise performance were between 100 and 500mg/kg/day.     

Chemotherapy-induced hemolytic uremic syndrome: Description of a potential animal model

Hemolytic uremic syndrome (HUS) is an uncommon complication of chemotherapy that contributes to the morbidity of oncology and bone marrow transplant patients. The pathogenesis is not well understood and no established clinical animal model exists. We studied four rhesus monkeys (RM) that developed fatal HUS following high-dose chemotherapy. Microangiopathic hemolytic anemia (pre-Hct 40% and day 5–8 Hct 31 % (P <.05), increased BUN (168 mg/dl), creatinine (8.2 mg/dl), and lactate dehydrogenase (1458 IU/L) (mean day 5–8 measurements) were observed. Platelets counts decreased to 39±15 × 10⁹/l from a mean of 397±31 × 10⁹/L (P < .0001). vWF, AT_III, thrombin:anti-thrombin complex (T:AT) and prothrombin fragment F1.2 levels were not different from a control group (N = 2). The data presented describe chemotherapy-induced HUS with typical clinical and laboratory features which may provide an animal model for the study of this important syndrome.     

Taurine concentration in the brain and in the plasma following intraperitoneal injections

Summary. The effect of different taurine doses (0.050, 0.125, 0.250, 0.500 and 1.000g/kg) administered intraperitoneally to Wistar rats was studied in both the plasma and the hippocampal microdialysate content.The samples were analyzed by reverse phased HPLC for the microdialysate samples and by HPLC with ion-exchange post-column derivatization (ninhydrin) for the plasma samples.In both plasma and microdialysate, we observed a dose dependent increase of taurine concentration. The AUC curves obtained from both microdialysate and plasma samples showed that the increase of taurine concentrations were linear. The mean ratio between AUCs microdialysate and plasma was 1.63±0.21 showing thus an unbalance between plasma and brain taurine content; a mechanism which enhance taurine transfer from the plasma to the brain was assumed.     

Relative value of the inion and mid-parietal locations as additional recording sites in pattern reversal visual evoked potentials

Although the P100 response of pattern reversal visual evoked potentials (PRVEPs) is most commonly recorded from the midline occipital site (MO), the response at this location can occasionally be absent or poorly defined due to anatomical variability of the visual cortex. In these cases, the American Electroencephalographic Society Evoked Potential Guidelines recommends recording from the mid-parietal (MP) and Inion electrode sites. In this study, we compared the amplitude of the P100 component recorded simultaneously from MO, MP and the Inion. PRVEPs obtained following stimulation with 30′ check sizes from 155 consecutive patients (310 eyes) over a 2 year period were analyzed. At each of the 3 recording sites, the peak amplitude of P100 was calculated as N75-P100, P100-N145, and the sum of N75-P100 and P100-N145. There was a statistically significant difference between the electrode sites for all 3 methods of amplitude measurement (one-way ANOVA; P<0.0001). For each method of measurement, there was no significant difference between P100 amplitude at MO or the Inion, but a significantly reduced amplitude at MP compared to both the MO and Inion electrode sites (post hoc Scheffe, P<0.05). The P100 amplitude was highest at the Inion in 18% of responses, including cases where the amplitude at that site was at least twice that at MO. In no case was the amplitude highest at MP. Our results indicate that the Inion is a better recording site compared to MP when acquiring PRVEPs, is often complementary to MO, and should be the first additional site to be used when extra channels are available.     

Taurine restores ethanol-induced depletion of antioxidants and attenuates oxidative stress in rat tissues

Summary. Ethanol by its property of generating free radicals during the course of its metabolism causes damage to cell structure and function. The study investigates the protective effects of the antioxidant aminoacid taurine on ethanol-induced lipid peroxidation and antioxidant status. Male Wistar rats of body weight 170–190g were divided into 4 groups and maintained for 28 days as follows: a control group and taurine-supplemented control group, taurine supplemented and unsupplemented ethanol-fed group. Ethanol was administered to rats at a dosage of 3g/kg body weight twice daily and taurine was provided in the diet (10g/kg diet). Lipid peroxidation products and antioxidant potential were quantitated in plasma and in following tissues liver, brain, kidney and heart.Increased levels of thiobarbituric acid substances (TBARS) and lipid hydroperoxides (LHP) in plasma and tissues, decreased activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were observed in hemolysate and tissues of ethanol-fed rats. The contents of reduced glutathione (GSH), -tocopherol and ascorbic acid in plasma and tissues were significantly reduced in these animals as compared to control animals. Simultaneous administration of taurine along with ethanol attenuated the lipid peroxidation process and restored the levels of enzymatic and non-enzymatic antioxidants. We propose that taurine may have a bioprotective effect on ethanol-induced oxidative stress.     

Relation of olfactory event-related potentials to changes in stimulus concentration

Objective: The aim of this study was to investigate the influence of odorant concentration on the olfactory event-related potential (OERP).Design and Methods: OERP were evaluated in 8 men and 8 women (17–34 years of age) in response to 4 concentrations of vanillin (7, 28, 56 and 84% v/v). Sixteen presentations of each concentration (stimulus duration 200 ms, interval 40 s, flow 8 l/min) were applied in a randomized order. EEG recordings were made at 3 midline sites (pos. Fz, Cz, Pz). Amplitudes and latencies of four peaks were measured (latencies in ms at Pz after stimulation with 84% v/v vanillin): P1 (277), N1 (348), P2 (412) and P3 (496). Statistical analysis was performed with MANOVAs (`concentration', `recording site'=within-subject-factors; `age' as covariate).Results: With increasing stimulus concentration amplitudes became significantly larger; this was most pronounced for P3 (P1N1: F=2.90, P<0.05; N1P2: F=5.15, P<0.01; N1P3: F=35.7, P<0.001; P3: F=38.6; P<0.001). Correspondingly, latencies shortened with increasing concentrations (P1: F=25.2; N1: 17.51; P2: 14.8; P3: 13.4; all P<0.001). While there was no correlation between OERP amplitudes and butanol odor detection thresholds, latencies were the shorter the lower the subjects' thresholds (coefficients of correlations for peak latencies at Cz for 84% v/v: P1 r₁₅=minus0.59; N1 r₁₅=minus0.58; P2 r₁₅=minus0.55; P3 r₁₅=minus0.45).Conclusions: The results indicated that both OERP amplitudes and latencies are related to the concentration of olfactory stimuli. They also suggested that latencies exhibit a stronger relation to changes in stimulus intensity compared to OERP amplitudes.