Potential role of kinins in the effects of taurine in high-fructose-fed rats

Ameliorative effect of taurine against diabetes and renal-associated disorders (Review)

To develop novel therapeutic methods for both diabetic and renal disorders, scientists had initially focused on elucidating the molecular mechanisms of taurine in established cell lines and mouse models. Although a large amount of data have been revealed, taurine has been confirmed to be the next step of novel promising therapeutic interventions against diabetic disorders. Taurine appears to ameliorate diabetes 1-related complications in various organs through its antioxidant, anti-inflammatory and anti-hormonal actions. In type 2 diabetes, taurine has been positively implicated in glucose homeostasis, exerting potent hypoglycemic, anti-obesity, hypotensive and hypolipidemic effects. Of particular interest is that taurine provides protection against renal dysfunction, including hypertension and proteinuria, specific glomerular and tubular disorders, acute and chronic renal conditions, and diabetic nephropathy. The ameliorative effects of taurine against renal disorders are based on its osmoregulatory properties, its association with signaling pathways and its association with the renin-angiotensin-aldosterone system (RAAS). Further clinical studies are required to ensure the importance of research findings.

Metabolic Syndrome and Its Components Are Associated With Altered Amino Acid Profile in Chinese Han Population

OBJECTIVE

Recent studies have found that the levels of plasma amino acids, such as branched-chain amino acids and aromatic amino acids, were associated with visceral obesity, insulin resistance, future development of diabetes and cardiovascular diseases. However, few studies have involved a Chinese Han population. This study aimed to examine the association between amino acid profile and metabolic syndrome (MetS) and its components in the Chinese Han population.

METHODS

This is a cross-sectional study, which enrolled a cohort of 473 participants from a community. We employed the isotope internal standard method to determine the plasma concentrations of 28 amino acids using high-performance liquid chromatography-tandem mass spectrometry (LC/MS). Participants were divided into MetS (n = 72) and non-MetS groups (n = 401) to analyze the association between amino acids and MetS and its components.

RESULTS

The prevalence of MetS was 15.2% according to the criteria. Plasma concentrations of isoleucine (Ile), leucine (Leu), valine (Val), tyrosine (Tyr), tryptophan (Trp), phenylalanine (Phe), glutamic acid (Glu), aspartic acid (Asp), alanine (Ala), histidine (His), methionine (Met), asparagine (Asn), and proline (Pro) were significantly higher in the MetS group than those in the non-MetS group (P < 0.05), but taurine (Tau) was significantly lower (P < 0.05). When MetS components were increased, the concentrations of these 13 amino acids significantly increased (P < 0.05), but Tau concentration was significantly decreased (P < 0.05). We extracted the amino acid profile by principal component analysis (PCA), PC1 and PC2, which extracted from the 14 amino acids, were significantly associated with MetS (odds ratio, 95% confidence interval: 1.723, 1.325-2.085 and 1.325, 1.043-1.684, respectively). A total of 260 non-MetS participants were followed up effectively, and 42 participants developed new-onset MetS within 5 years. We found that the amino acid profile of PC1 was linked to the occurrence of future MetS. Decreased Tau was correlated with the future development of MetS.

CONCLUSION

Participants with MetS exhibit an abnormal amino acid profile, and its components gradually increase when these amino acids are altered. Amino acid PCA profile can be employed for assessing and monitoring MetS risk. Finally, decreased Tau may be linked to the future development of MetS.

Taurine Supplementation Reduces Renal Nerve Activity in Male Rats in which Renal Nerve Activity was Increased by a High Sugar Diet

This study tests the hypothesis that taurine supplementation reduces sugar-induced increases in renal sympathetic nerve activity related to renin release in adult male rats. After weaning, male rats were fed normal rat chow and drank water containing 5% glucose (CG) or water alone (CW) throughout the experiment. At 6-7 weeks of age, each group was supplemented with or without 3% taurine in drinking water until the end of experiment. At 7-8 weeks of age, blood chemistry and renal nerve activity were measured in anesthetized rats. Body weights slightly and significantly increased in CG compared to CW groups but were not significantly affected by taurine supplementation. Plasma electrolytes except bicarbonate, plasma creatinine, and blood urea nitrogen were not significantly different among the four groups. Mean arterial pressure significantly increased in both taurine treated groups compared to CW, while heart rates were not significantly different among the four groups. Further, all groups displayed similar renal nerve firing frequencies at rest and renal nerve responses to sodium nitroprusside and phenylephrine infusion. However, compared to CW group, CG significantly increased the power density of renin release-related frequency component, decreased that of sodium excretion-related frequency component, and decreased that of renal blood flow-related frequency component. Taurine supplementation completely abolished the effect of high sugar intake on renal sympathetic activity patterns. These data indicate that in adult male rats, high sugar intake alters the pattern but not firing frequency of sympathetic nerve activity to control renal function, and this effect can be improved by taurine supplementation.

Impact of chronic administration of anabolic androgenic steroids and taurine on blood pressure in rats

Supraphysiological administration of anabolic androgenic steroids has been linked to increased blood pressure. The widely distributed amino acid taurine seems to be an effective depressor agent in drug-induced hypertension. The purpose of this study was to assess the impact of chronic high dose administration of nandrolone decanoate (DECA) and taurine on blood pressure in rats and to verify the potentially involved mechanisms. The study was conducted in 4 groups of 8 adult male Wistar rats, aged 14 weeks, treated for 12 weeks with: DECA (A group); vehicle (C group); taurine (T group), or with both drugs (AT group). Systolic blood pressure (SBP) was measured at the beginning of the study (SBP₁), 2 (SBP₂) and 3 months (SBP₃) later. Plasma angiotensin-converting enzyme (ACE) activity and plasma end products of nitric oxide metabolism (NO_x) were also determined. SBP₃ and SBP₂ were significantly increased compared to SBP₁ only in the A group (P<0.002 for both). SBP₂, SBP₃ and ACE activity showed a statistically significant increase in the A vs C (P<0.005), andvs AT groups (P<0.05), while NO_x was significantly decreased in the A and AT groups vs controls (P=0.01). ACE activity was strongly correlated with SBP₃ in the A group (r=0.71, P=0.04). These findings suggest that oral supplementation of taurine may prevent the increase in SBP induced by DECA, an effect potentially mediated by angiotensin-converting enzyme.

Radiation protection following nuclear power accidents: a survey of putative mechanisms involved in the radioprotective actions of taurine during and after radiation exposure

There are several animal experiments showing that high doses of ionizing radiation lead to strongly enhanced leakage of taurine from damaged cells into the extracellular fluid, followed by enhanced urinary excretion. This radiation-induced taurine depletion can itself have various harmful effects (as will also be the case when taurine depletion is due to other causes, such as alcohol abuse or cancer therapy with cytotoxic drugs), but taurine supplementation has been shown to have radioprotective effects apparently going beyond what might be expected just as a consequence of correcting the harmful consequences of taurine deficiency per se. The mechanisms accounting for the radioprotective effects of taurine are, however, very incompletely understood. In this article an attempt is made to survey various mechanisms that potentially might be involved as parts of the explanation for the overall beneficial effect of high levels of taurine that has been found in experiments with animals or isolated cells exposed to high doses of ionizing radiation. It is proposed that taurine may have radioprotective effects by a combination of several mechanisms: (1) during the exposure to ionizing radiation by functioning as an antioxidant, but perhaps more because it counteracts the prooxidant catalytic effect of iron rather than functioning as an important scavenger of harmful molecules itself, (2) after the ionizing radiation exposure by helping to reduce the intensity of the post-traumatic inflammatory response, and thus reducing the extent of tissue damage that develops because of severe inflammation rather than as a direct effect of the ionizing radiation per se, (3) by functioning as a growth factor helping to enhance the growth rate of leukocytes and leukocyte progenitor cells and perhaps also of other rapidly proliferating cell types, such as enterocyte progenitor cells, which may be important for immunological recovery and perhaps also for rapid repair of various damaged tissues, especially in the intestines, and (4) by functioning as an antifibrogenic agent. A detailed discussion is given of possible mechanisms involved both in the antioxidant effects of taurine, in its anti-inflammatory effects and in its role as a growth factor for leukocytes and nerve cells, which might be closely related to its role as an osmolyte important for cellular volume regulation because of the close connection between cell volume regulation and the regulation of protein synthesis as well as cellular protein degradation. While taurine supplementation alone would be expected to exert a therapeutic effect far better than negligible in patients that have been exposed to high doses of ionizing radiation, it may on theoretical grounds be expected that much better results may be obtained by using taurine as part of a multifactorial treatment strategy, where it may interact synergistically with several other nutrients, hormones or other drugs for optimizing antioxidant protection and minimizing harmful posttraumatic inflammatory reactions, while using other nutrients to optimize DNA and tissue repair processes, and using a combination of good diet, immunostimulatory hormones and perhaps other nontoxic immunostimulants (such as beta-glucans) for optimizing the recovery of antiviral and antibacterial immune functions. Similar multifactorial treatment strategies may presumably be helpful in several other disease situations (including severe infectious diseases and severe asthma) as well as for treatment of acute intoxications or acute injuries (both mechanical ones and severe burns) where severely enhanced oxidative and/or nitrative stress and/or too much secretion of vasodilatory neuropeptides from C-fibres are important parts of the pathogenetic mechanisms that may lead to the death of the patient. Some case histories (with discussion of some of those mechanisms that may have been responsible for the observed therapeutic outcome) are given for illustration of the likely validity of these concepts and their relevance both for treatment of severe infections and non-infectious inflammatory diseases such as asthma and rheumatoid arthritis.

High sugar intake via the renin-angiotensin system blunts the baroreceptor reflex in adult rats that were perinatally depleted of taurine

Perinatal taurine depletion leads to several physiological impairments in adult life, in part, due to taurine’s effects on the renin-angiotensin system, a crucial regulator of growth and differentiation during early life. The present study tests the hypothesis that perinatal taurine depletion predisposes adult female rats to impaired baroreceptor control of arterial pressure by altering the renin-angiotensin system. Female Sprague Dawley (SD) rats were fed normal rat chow and from conception to weaning drank 3% beta-alanine in water (taurine depletion, TD) or water alone (Control, C). Female offspring ate a normal rat chow and drank water with (G) or without (W) 5% glucose throughout the experiment. To test the possible role of the renin-angiotensin system, 50% of the rats received captopril (an angiotensin converting enzyme inhibitor, 400 mg/L) from 7 days before parameter measurements until the end of experiment. At 7-8 weeks of age, arterial pressure, heart rate, baroreflex control of heart rate and renal nerve activity were studied in either conscious, freely moving or anesthetized rats. Perinatal taurine depletion did not alter resting mean arterial pressure or heart rate in the adult female offspring that received either high or normal sugar intake. Captopril treatment slightly decreased mean arterial pressure but not heart rate in all groups. Compared to controls, only the TDG rats displayed blunted baroreflex responses. Captopril treatment normalized baroreflex sensitivity in TDG. The present data indicate that in perinatal taurine depleted female rats, the renin-angiotensin system underlines the ability of high sugar intake to blunt baroreceptor responses.

Sex dependent effects of perinatal taurine exposure on the arterial pressure control in adult offspring

The present study tests the sex-dependent effect of perinatal taurine exposure on arterial pressure control in adults. Female Sprague-Dawley rats were fed normal rat chow with 3% beta-alanine (taurine depletion,TD), 3% taurine (taurine supplementation,TS) or water alone (C) from conception to weaning. Their male and female offspring were then fed normal rat chow and tap water with 5% glucose (C with glucose, CG; TD with glucose, TDG; TS with glucose, TSG) or water alone (CW, TDW or TSW). At 7-8 weeks of age, they were studied in a conscious condition. Body weights were lower in male and female TDG and male TDW rats. Kidney to body weights increased in female TSW but not TSG. Plasma sodium and potassium were not significantly different among males. Among females, plasma sodium levels were lower in all glucose treated groups while plasma potassium levels were lower only in TDG. Hematocrit, fasting blood glucose, and glucose tolerance were not significantly different between the sexes. Mean arterial pressure increased in male TDG, TSW, and TSG while in the females, mean arterial pressure increased in TabstractDW, TDG, and TSG. Heart rates were not significantly different between the sexes. The present data indicate that perinatal taurine exposure alters arterial pressure control of adult rats and this effect is gender specific.

TAURINE ATTENUATES HYPERTENSION AND RENAL DYSFUNCTION INDUCED BY CYCLOSPORINE A IN RATS

Cyclosporine A (CsA) is the first-line immunosuppressant used for the management of solid organ transplantation and autoimmune diseases. Nephrotoxicity is the major limitation of CsA use. Recent evidence suggests that reactive oxygen species (ROS) play an important role in mediating CsA-induced hypertension and nephrotoxicity. Taurine, the major intracellular free beta-amino acid, is known to be an endogenous anti-oxidant and membrane-stabilizing agent. The present study was designed to investigate the effects of taurine on CsA-induced oxidative stress, hypertension and renal dysfunction. 2. Animals were assigned into four groups of seven rats each as follows: (i) control group, receiving vehicle (olive oil; 1 mL/kg, s.c.); (ii) CsA group, given CsA (25 mg/kg per day, s.c.) for 21 days; (iii) taurine group, supplemented with taurine (1% in the drinking water); and (iv) taurine + CsA group, treated with taurine 3 days before and concurrently during CsA injections for 21 days. 3. Cyclosporine A administration elevated blood pressure, reduced serum nitric oxide (NO) levels and deteriorated renal function, as assessed by increased serum creatinine levels and proteinuria and reduced urine flow rate and creatinine clearance compared with vehicle-treated rats. Cyclosporine A induced oxidative stress, as indicated by increased renal tissue concentrations of thiobarbituric acid-reactive substances and reduced concentrations of renal glutathione, glutathione peroxidase and superoxide dismutase. Conversely, no change was noted in renal catalase activity. Moreover, the kidneys of CsA-treated rats showed interstitial inflammation and renal tubular atrophy. 4. Taurine markedly reduced elevated blood pressure, attenuated renal dysfunction and the reduction in serum NO levels and counteracted the deleterious effects of CsA on oxidative stress markers. Furthermore, taurine ameliorated CsA-induced morphological changes. 5. These data clearly indicate the protective potential of taurine against CsA-induced hypertension and nephrotoxicity and suggest a significant contribution of its anti-oxidant property to this beneficial effect.