Effectiveness of taurine in protecting biomembrane against oxidant

Effects of different methionine sources on production and reproduction performance, egg quality and serum biochemical indices of broiler breeders

Objective

The study was conducted to evaluate the effects of different methionine (Met) sources on production performance, reproduction performance, egg quality and serum biochemical indices in broiler breeders.

Methods

After receiving a basal diet (containing 0.25% Met) for a 2-wk pretreatment period, a total of 360 39-wk-old Lingnan yellow broiler breeders were randomly allocated to four treatments with six replicates each (15 birds per replicate). Breeders were fed with basal diets (control) or diets supplemented with DL-methionine (DLM), DL-2-hydroxy-4-methylthio butytric calcium (MHA-Ca) and coated DL-Met (CME) respectively.

Results

The results showed that CME supplementation promoted laying rate and decreased feed-to-egg ratio (F/E) (p<0.05), DLM and MHA-Ca supplementation decreased F/E (p<0.05) when compared with control group. The rate of fertility, hatchability and birthrate were higher (p<0.05) in DLM, MHA-Ca, and CME groups than control group. Compared with control group, CME increased the eggshell thickness (p<0.05); MHA-Ca improved the eggshell thickness, shell ratio and eggshell strength (p<0.05). Results also showed that CME elevated the concentration of total protein in serum (p<0.05); MHA-Ca improved the concentration of calcium in serum (p<0.05). The concentration of serum uric acid in DLM, MHA-Ca, and CME groups was lower than that in control group (p<0.05). Besides, CME had higher concentrations of serum taurine, cysteine and cystanthionine (p<0.05) while MHA-Ca and DLM promoted the serum taurine concentration (p<0.05) compared with control group.

Conclusion

Based on the results, it was concluded that Met supplementation could enhance the production and reproduction performance as well as the antioxidant status and egg quality of broiler breeders. In terms of improving the production performance, reproduction performance and antioxidant performance, CME was superior to DLM and MHA-Ca; but in regard to the enhancement of eggshell quality and serum Ca concentration, MHA-Ca was superior to DLM and CME.

Peroxynitrite induced decrease in Na+, K+-ATPase activity is restored by taurine

AIM: Peroxynitrite (ONOO^-) is a powerful oxidant shown to damage membranes. In the present study, the effect of taurine on changes of liver plasma membrane Na⁺, K⁺-ATPase induced by ONOO^- was investigated.

METHODS: Liver plasma membrane was exposed to ONOO^- with or without taurine. Na⁺, K⁺-ATPase activity and lipid peroxidation as thiobarbituric acid reactive substances (TBARS) levels were measured.

RESULTS: Different concentrations of ONOO^- (100, 200, 500, and 1000 μmol/L) were found to decrease liver plasma membrane Na⁺, K⁺-ATPase activity significantly. The depletion of enzyme activity was not concentration dependent. Effects of different concentrations of taurine on liver plasma membrane Na⁺, K⁺-ATPase activity were also measured. Taurine did not cause any increase in enzyme activity. When plasma membranes were treated with 200 μmol/L ONOO^- with different concentrations of taurine, a restoring effect of taurine on enzyme activity was observed. TBARS levels were also measured and taurine was found to decrease the elevated values.

CONCLUSION: Taurine is observed to act as an antioxidant of ONOO^- to decrease lipid peroxidation and thus affect liver plasma membrane Na⁺, K⁺-ATPase by restoring its activity.

Hypochlorous acid-induced oxidative damage of human red blood cells: effects of tert-butyl hydroperoxide and nitrite on the HOCl reaction with erythrocytes

Hypochlorous acid, one of the most powerful biological oxidants, is believed to be important in the pathogenesis of some diseases. The purpose of this study was to further characterise the membrane and intracellular events which resulted in HOCl-induced oxidative impairments and haemolysis of human erythrocytes and interaction of different oxidative agents, which accumulated during respiratory burst, in the process of RBS oxidation. The sequence of cellular events after red blood cell exposure to HOCl: cell morphological transformations, oxidation of cellular constituents, enzyme modifications, and haemolysis have been evaluated. It was shown that HOCl-treated cells underwent colloid-osmotic haemolysis, preceded by rapid morphological transformations and membrane structural transitions. The activation energy of the process of haemolysis (after removal of the excess of oxidative agent) was estimated to be 146+/-22 kJ/mol at temperatures above the break point of Arrhenius plot (31-32 degrees C). This value corresponds to the activation energy of the process of protein denaturation. Modification of erythrocytes by HOCl inhibited membrane acetylcholinesterase (uncompetitive type of inhibition), depleted intracellular glutathione, activated intracellular glutathione peroxidase, but did not induce membrane lipid peroxidation. The presence of other oxidants, nitrite or tert-butyl hydroperoxide (t-BHP), promoted the oxidative damage induced by HOCl and led to new oxidative reactions.

Ethanol and amino acids in the central nervous system: assessment of the pharmacological actions of acamprosate

Ethanol induces alterations in the central nervous system by differentially interfering with a number of neurotransmitter systems, although the mechanisms by which such effects are executed are not well understood. The present review therefore, is designed to ascertain the effect of ethanol on both excitatory and inhibitory amino acid neurotransmitters, as well as the sulphonated amino acid taurine, assayed by the microdialysis technique within specific brain regions of rat during different types of alcohol intoxication, acute and chronic, as well as during the withdrawal period. Such an understanding of these pharmacological actions of ethanol on neurotransmitters is essential in order to provide the impetus for the development of appropriate therapeutic intervention to ameliorate the multitude of neurochemical disorders induced by ethanol. In addition the possible mode of action of a new therapeutic drug for the treatment of alcoholism, acamprosate will be discussed. The first part of this review will be limited to studies of the effect of ethanol on both amino acid neurotransmitters and the sulphonated amino acid taurine, a possible neuromodulator. While, the second part will seek to establish the possible mechanism of action of a new therapeutic drug, acamprosate, which is used to combat the effects of ethanol, particularly during the craving period, as well as maintaining abstinence in weaned alcoholics.

The mechanisms of taurine mediated protection against cell damage induced by hypoxia and reoxygenation

Taurine administered during hypoxia markedly reduced the cell damage due to O2 deficiency and reoxygenation. Different mechanisms are responsible for the improved survival of the renal cell cultures. Taurine markedly reduces the osmoregulatory deterioration during hypoxia and reoxygenation. Calcium homeostasis was markedly improved. Ca2+ efflux during hypoxia as well as Ca2+ overload during reoxygenation was significantly reduced by the amino acid. The effect of taurine was partly comparable to the effect induced by Ca2+ channel blockers. One of the effects mainly responsible for cellular protection seems to be the taurine-induced acceleration of cellular growth processes in spite of hypoxia and reoxygenation. The spectrum of cytoprotective effects of taurine predisposes this substance to be a physiological protective agent responsible for cellular homeostasis or enantiostasis.

Protective effect of taurine on hypoxia and reoxygenation-induced damage of human colon cells (HT 29)

In this experimental model, taurine administered during hypoxia markedly reduced the cell damage due to O2 deficiency, and the beneficial effect outlasted the period of reoxygenation. The mechanisms for the improved survival rates are postulated to be a reduced osmoregulatory disturbance of cellular integrity, improved Ca2+ homeostasis and induction of accelerated cellular growth processes. In our simplified cell culture model the UW solution seems to be the most appropriate solution for the cold (hypoxic) preservation of human colon cells. We conclude, that within this experimental model and under these experimental conditions, taurine supplementation of the conventionally used preservation solutions improved the solutions markedly. Considering our previous studies, taurine seems to be a potent endogenous protective agent against cellular deterioration due to hypoxia and reoxygenation.

Beneficial effects of taurine on mouse zygotes developing in protein-free culture medium

The objectives of this study were to determine if mouse zygotes from outbred mice can develop in simple culture medium in the absence of bovine serum albumin (BSA), and if taurine can be used as a medium supplement to improve development. Zygotes from 2 stocks of outbred mice (CD-1 and CF-1) were cultured in simple embryo culture medium (TE medium) lacking BSA and with or without taurine (24 mM), or in regular TE medium with BSA. The presence of BSA had little or no effect on development, but development to post-blastocyst endpoints was enhanced when CD-1 zygotes were cultured in medium containing taurine. In addition, when CD-1 blastocysts were transferred to pseudopregnant animals, embryos cultured in the presence of taurine developed into fetuses more often than those cultured in medium without taurine, and their weights were higher than those of embryos cultured in regular TE medium with BSA. These beneficial effects of taurine do not appear to be the nonspecific effects of a fixed nitrogen source, because the addition of glycine to BSA-free TE medium did not have similar beneficial effects. It was concluded that mouse zygotes from outbred mice do not require BSA for their preimplantation development in culture and that the presence of taurine in preimplantation culture medium is beneficial not only for preimplantation development of the zygotes, but also for their post-blastocyst development.

Protecting effect of taurine against hypoxic cell damage in renal tubular cells cultured in different transplant preservation solutions

We conclude that, within this experimental model and under these experimental conditions, taurine supplementation of standard kidney preservation solutions improves survival of kidney cells during hypoxic preservation. The protective effect depends on the taurine concentration, the hypoxic preservation time and the used preservation solution. Physiological taurine concentrations are effective during short hypoxic periods, whereas pharmacological taurine concentrations seem to be needed for longer periods of hypoxia. Within this experimental model University of Wisconsin solution seems to be more effective than Euro collins solution.

Taurine and niacin offer a novel therapeutic modality in prevention of chemically-induced pulmonary fibrosis in hamsters

The bleomycin (BL)-hamster model of interstitial pulmonary fibrosis (IPF) is generally associated with increased lung lipid peroxidation, measured as malondialdehyde equivalent (MDAE), calcium and collagen content; and superoxide dismutase (SOD), prolyl hydroxylase (PH) and poly(ADP-ribose) polymerase activities. We found that combined treatment with taurine in drinking water (1%) and niacin IP (250 mg/kg) daily, significantly decreased the BL-induced increases in lung MDAE and calcium content, and SOD, PH and poly(ADP-ribose) polymerase activities. This treatment almost completely ameliorated the BL-induced increases in the lung collagen accumulation as well. Findings of a similar nature were also demonstrated when taurine (2.5%) and niacin (2.5%) were supplemented in the diet of hamsters used in the same BL model of IPF. The diet supplemented with taurine (2.5%), niacin (2.5%), or taurine (2.5%) + niacin (2.5%) also reduced AD-induced increases in lung collagen accumulation, phospholipids, MDAE and SOD activity. It was concluded that diet supplemented with taurine and/or niacin would completely or partially ameliorate chemically-induced pulmonary fibrosis.