Taurine-diabetes interaction: from involvement to protection

Taurine Supplementation for 48-Months Improved Glucose Tolerance and Changed ATP-Related Enzymes in Avians

Avians differ from mammals, especially in brain architecture and metabolism. Taurine, an amino acid basic to metabolism and bioenergetics, has been shown to have remarkable effects on metabolic syndrome and ameliorating oxidative stress reactions across species. However, less is known regarding these metabolic relationships in the avian model. The present study serves as a preliminary report that examined how taurine might affect avian metabolism in an aged model system. Two groups of pigeons (Columba livia) of mixed sex, a control group and a group that received 48 months of taurine supplementation (0.05% w/v) in their drinking water, were compared by using blood panels drawn from their basilic vein by a licensed veterinarian. From the blood panel data, taurine treatment generated higher levels of three ATP-related enzymes: glutamate dehydrogenase (GLDH), lactate dehydrogenase (LDH), and creatine kinase (CK). In this preliminary study, the role that taurine treatment might play in the adult aged pigeon's metabolism on conserved traits such as augmenting insulin production as well as non-conserved traits maintaining high levels of ATP-related enzymes was examined. It was found that taurine treatment influenced the avian glucose metabolism similar to mammals but differentially effected avian ATP-related enzymes in a unique way (i.e., ∼×2 increase in CK and LDH with a nearly ×4 increase in GLDH). Notably, long-term supplementation with taurine had no negative effect on parameters of lipid and protein metabolism nor liver enzymes. The preliminary study suggests that avians may serve as a unique model system for investigating taurine metabolism across aging with long-term health implications (e.g., hyperinsulinemia). However, the suitability of using the model would require researchers to tightly control for age, sex, dietary intake, and exercise conditions as laboratory-housed avian present with very different metabolic panels than free-flight avians, and their metabolic profile may not correlate one-to-one with mammalian data.

Early taurine administration as a means for halting the cytokine storm progression in COVID-19 patients

Around the world, more than 6.2 million individuals have died as a result of coronavirus disease 2019 (COVID-19). According to a recent survey conducted among immunologists, epidemiologists, and virologists, this disease is expected to become endemic. This implies that the disease could have a continuous presence and/or normal frequency in the population. Pharmacological interventions to prevent infection, as well as to treat the patients at an early phase of illness to avoid hospitalization are essential additions to the vaccines. Taurine is known to inhibit the generation of all inflammatory mediators linked to the cytokine storm. It can also protect against lung injury by suppressing increased oxidants production and promoting the resolution of the inflammatory process. Neutrophil lactoferrin degranulation stimulated by taurine may have antiviral effects against SARS-CoV-2, limiting viral replication. It is hypothesized that if taurine is administered early in the onset of COVID-19 disease, it may stop the cytokine storm from progressing, lowering morbidity and mortality.

Amino Acid Nanofibers Improve Glycemia and Confer Cognitive Therapeutic Efficacy to Bound Insulin

Diabetes poses a high risk for debilitating complications in neural tissues, regulating glucose uptake through insulin-dependent and predominantly insulin-independent pathways. Supramolecular nanostructures provide a flexible strategy for combinatorial regulation of glycemia. Here, we compare the effects of free insulin to insulin bound to positively charged nanofibers comprised of self-assembling amino acid compounds (AACs) with an antioxidant-modified side chain moiety (AAC2) in both in vitro and in vivo models of type 1 diabetes. Free AAC2, free human insulin (hINS) and AAC2-bound-human insulin (AAC2-hINS) were tested in streptozotocin (STZ)-induced mouse model of type 1 diabetes. AAC2-hINS acted as a complex and exhibited different properties compared to free AAC2 or hINS. Mice treated with the AAC2-hINS complex were devoid of hypoglycemic episodes, had improved levels of insulin in circulation and in the brain, and increased expression of neurotransmitter taurine transporter, Slc6a6. Consequently, treatment with AAC2-hINS markedly advanced both physical and cognitive performance in mice with STZ-induced and genetic type 1 diabetes compared to treatments with free AAC2 or hINS. This study demonstrates that the flexible nanofiber AAC2 can serve as a therapeutic platform for the combinatorial treatment of diabetes and its complications.

Taurine supplementation in conjunction with exercise modulated cytokines and improved subcutaneous white adipose tissue plasticity in obese women

Interventions that can modulate subcutaneous white adipose tissue (scWAT) function, such as exercise training and nutritional components, like taurine, modulate the inflammatory process, therefore, may represent strategies for obesity treatment. We investigated the effects of taurine supplementation in conjunction with exercise on inflammatory and oxidative stress markers in plasma and scWAT of obese women. Sixteen obese women were randomized into two groups: Taurine supplementation group (Tau, n = 8) and Taurine supplementation + exercise group (Tau + Exe, n = 8). The intervention was composed of daily taurine supplementation (3 g) and exercise training for 8 weeks. Anthropometry, body fat composition, and markers of inflammatory and oxidative stress were determined in plasma and scWAT biopsy samples before and after the intervention. We found that, although taurine supplementation increased taurine plasma levels, no changes were observed for the anthropometric characteristics. However, Tau alone decreased interleukin-6 (IL-6), and in conjunction with exercise (Tau + Exe), increased anti-inflammatory interleukins (IL-15 and IL10), followed by reduced IL1β gene expression in the scWAT of obese women. Tau and Tau + Exe groups presented reduced adipocyte size and increased connective tissue and multilocular droplets. In conclusion, taurine supplementation in conjunction with exercise modulated levels of inflammatory markers in plasma and scWAT, and improved scWAT plasticity in obese women, promoting protection against obesity-induced inflammation. TRN NCT04279600 retrospectively registered on August 18, 2019.

Therapeutic Effectiveness of Gardenia jasminoides on Type 2 Diabetic Rats: Mass Spectrometry-Based Metabolomics Approach

Gardenia jasminoides fruits, a kind of traditional Chinese medicine (TCM), have shown prospects in the prevention of diabetes and its complications. However, due to their chemical diversity and multiple biological targets, the effective mechanism remains largely unknown. In this study, mass spectrometry-based metabolomics was applied to uncover the underlying therapeutic mechanism of G. jasminoides on type 2 diabetes (T2D) and its clinical complications. We established a T2D rat model using high-fat diet and identified 45 urinary endogenous metabolites as potential diagnostic biomarkers for T2D rats. After treatment with G. jasminoides, pathologic symptoms of T2D rats were significantly improved and some of the diagnostic biomarkers were significantly regulated. Bioinformatics analysis demonstrated that these therapeutic biomarkers were involved in bile acid biosynthesis, amino acid metabolism, vitamin B metabolism, taurine metabolism, etc., which indicated potential therapeutic mechanisms of G. jasminoides on T2D and its complications.

Metabolomics approach revealed robust changes in amino acid and biogenic amine signatures in patients with schizophrenia in the early course of the disease

The primary objective of this study was to evaluate how schizophrenia (SCH) spectrum disorders and applied antipsychotic (AP) treatment affect serum level of amino acids (AAs) and biogenic amines (BAs) in the early course of the disorder. We measured 21 different AAs and 10 BAs in a sample of antipsychotic (AP)-naïve first-episode psychosis (FEP) patients (n = 52) at baseline, after 0.6-year as well as after 5.1-year treatment compared to control subjects (CSs, n = 37). Serum levels of metabolites were determined with AbsoluteIDQ p180 kit using flow injection analysis tandem mass spectrometry and liquid chromatography technique. Elevated level of taurine and reduced level of proline and alpha-aminoadipic acid (alpha-AAA) were established as metabolites with significant change in AP-naïve FEP patients compared to CSs. The following 0.6-year treatment restored these alterations. However, further continuous 5.1-year AP treatment changed the metabolic profile substantially. Significantly elevated levels of asparagine, glutamine, methionine, ornithine and taurine, alongside with decreased levels of aspartate, glutamate and alpha-AAA were observed in the patient group compared to CSs. These biomolecule profile alterations provide further insights into the pathophysiology of SCH spectrum disorders and broaden our understanding of the impact of AP treatment in the early stages of the disease.

Ameliorative effects of taurine against diabetes: a review

Diets in rats and humans have shown promising results. Taurine improved glucagon activity, promoted glycemic stability, modified glucose levels, successfully addressed hyperglycemia via advanced glycation end-product control, improved insulin secretion and had a beneficial effect on insulin resistance. Taurine treatment performed well against oxidative stress in brain, increased the secretion of required hormones and protected against neuropathy, retinopathy and nephropathy in diabetes compared with the control. Taurine has been observed to be effective in treatments against diabetic hepatotoxicity, vascular problems and heart injury in diabetes. Taurine was shown to be effective against oxidative stress. The mechanism of action of taurine cannot be explained by one pathway, as it has many effects. Several of the pathways are the advanced glycation end-product pathway, PI3-kinase/AKT pathway and mitochondrial apoptosis pathway. The worldwide threat of diabetes underscores the urgent need for novel therapeutic measures against this disorder. Taurine (2-aminoethane sulfonic acid) is a natural compound that has been studied in diabetes and diabetes-induced complications.

Prophylactic role of taurine and its derivatives against diabetes mellitus and its related complications

Taurine is a conditionally essential amino acid present in the body in free form. Mammalian taurine is synthesized in the pancreas via the cysteine sulfinic acid pathway. Anti-oxidation and anti-inflammation are two main properties through which it exerts its therapeutic effects. Many studies have shown its excellent therapeutic potential against diabetes mellitus and related complications like diabetic neuropathy, retinopathy, nephropathy, hematological dysfunctions, reproductive dysfunctions, liver and pancreas related complications etc. Not only taurine, a number of its derivatives have also been reported to be important in ameliorating diabetic complications. The present review has been aimed to describe the importance of taurine and its derivatives against diabetic metabolic syndrome and related complications.

The effect of long-term taurine supplementation and fructose feeding on glucose and lipid homeostasis in Wistar rats

The nonprotein amino acid taurine has been shown to counteract the negative effects of a high-fructose diet in rats with regard to insulin resistance and dyslipidemia. Here we examined the long-term (26 weeks) effects of oral taurine supplementation (2% in the drinking water) in fructose-fed Wistar rats.The combination of fructose and taurine caused a significant increase in fasting glucose compared to the control diet without changing hepatic phosphoenol pyruvate carboxykinase mRNA levels. The combination of fructose and taurine also improved glucose tolerance compared to control. Neither a high-fructose diet nor taurine supplementation induced significant changes in body weight, body fat or total calorie intake, fasting insulin levels, HOMA-IR, or insulin-induced Akt phosphorylation in skeletal muscle.Fructose alone caused a decrease in liver triglyceride content, with taurine supplementation preventing this. There was no effect of long-term fructose diet and/or taurine supplementation on plasma triglycerides, plasma nonesterified fatty acids, as well as plasma HDL, LDL, and total cholesterol.In conclusion, the study suggests that long-term taurine supplementation improves glucose tolerance and normalize hepatic triglyceride content following long-term fructose feeding. However, as the combination of taurine and fructose also increased fasting glucose levels, the beneficial effect of taurine supplementation towards amelioration of glucose intolerance and insulin resistance may be questionable.

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.

Taurine may not alleviate hyperglycemia-mediated endoplasmic reticulum stress in human adipocytes

In obesity and diabetes, adipocytes show significant endoplasmic reticulum (ER) stress. Hyperglycemia-induced ER stress has not been studied in adipocyte differentiation and adipokine expression. Taurine has been known to protect the cells against ER stress. This study examined the effect of taurine on ER stress-induced adipocyte differentiation and adipokine expression to explain the therapeutic effect of taurine on diabetes and obesity. To do this, human preadipocytes were differentiated into adipocytes, in the presence or absence of taurine, under ER stress conditions. Changes in adipokine expression in adipocytes stimulated with IL-1β were investigated in the presence or absence of taurine. Human preadipocytes were treated with thapsigargin (10 nM) or high glucose concentrations (100 mM) as ER stress inducers during differentiation into adipocytes. Thapsigargin inhibited the differentiation of adipocytes in a dose-dependent manner, but the high glucose concentration treatment did not. Taurine 100 mM treatment did not block the inhibition of differentiation of preadipcytes into adipocytes. Furthermore, the high glucose concentration treatment inhibited the expression of adiponectin and increased the expression of leptin in human adipocytes. However, taurine treatment did not affect the expression of two adipokines. In conclusion, the therapeutic mechanism of taurine in diabetes and obesity does not appear to occur by alleviating hyperglycemia-mediated ER stress. To clarify the molecular mechanism by which taurine improves diabetic symptoms and obesity in animal models, the protective effect of taurine against hyperglycemia- or overnutrition-mediated ER stress should be further evaluated under various conditions or types of ER stress.

Perinatal taurine imbalance alters the interplay of renin-angiotensin system and estrogen on glucose-insulin regulation in adult female rats

Perinatal taurine depletion followed by high sugar intake (postweaning) alters the renin-angiotensin system (RAS) and glucose regulation in adult female rats. This study tests the hypothesis that in adult female rats, RAS and estrogen contribute to insulin resistance resulting from perinatal taurine imbalance. Female Sprague-Dawley rats were fed normal rat chow with 3% β-alanine (taurine depletion, TD), 3% taurine (taurine supplementation, TS), or water alone (control, C) from conception to weaning. Their female offspring were fed normal rat chow with 5% glucose in water (TDG, TSG, CG) or water alone (TDW, TSW, CW) throughout the experiment. At 7-8 weeks of age, animals were studied with or without captopril inhibition of the RAS and with or without estrogen receptor inhibition by tamoxifen. Compared to CW and CG groups, perinatal taurine depletion but not supplementation slightly increased plasma insulin levels. High sugar intake slightly increased plasma insulin only in TSG. Captopril treatment significantly increased plasma insulin in all groups except CG (the greatest increase was in TDG). Changes in insulin resistance and insulin secretion paralleled the changes in plasma insulin levels. In contrast, tamoxifen treatment increased insulin resistance and decreased insulin secretion only in TDG and this group displayed hyperglycemia and glucose intolerance. These data indicate that perinatal taurine imbalance alters the interplay of RAS and estrogen on glucose-insulin regulation in adult female rats.

Taurine in adipocytes prevents insulin-mediated H2O2 generation and activates Pka and lipolysis

Among many actions assigned to taurine (Tau), the most abundant amino acid in numerous mammalian tissues, it prevents high-fat diet-induced obesity with increasing resting energy expenditure. To sustain this Tau action, the goal of the present study was to explore the acute effects of Tau on baseline and on adrenaline, insulin and their second messengers to modulate lipolysis in white adipose tissue (WAT) cells from rat epididymis. The Tau effects in this topic were compared with those recorded with Gly, Cys and Met. Tau on its own did not modify baseline lipolysis. Tau raised isoproterenol- and dibutyryl-cAMP (Bt2cAMP)-activated glycerol release. Gly diminished Bt2cAMP-activated glycerol release, and Cys and Met had no effect. Cyclic AMP-dependent activation of protein kinase A (PKA) in cell-free extracts decreased slightly by Gly and was unaltered by Cys, Met, and Tau. PKA catalytic activity in cell-free extracts was stimulated by Tau and unchanged by Cys, Gly and Met. Gly and Tau effects on PKA disappeared when these amino acids were withdrawn by gel filtration. Insulin-mediated NADPH-oxidase (NOX) raises H2O2 pool, which promotes PKA subunit oxidation, and precludes its cAMP activation; thus, lipolysis is diminished. Tau, but not Cys, Gly and Met, inhibited, by as much as 70%, insulin-mediated H2O2 pool increase. These data suggested that Tau raised lipolysis in adipocytes by two mechanisms: stimulating cAMP-dependent PKA catalytic activity and favoring PKA activation by cAMP as a consequence of lowering the H2O2 pool.