Improvement in the expression of hepatic genes involved in fatty acid metabolism in obese rats supplemented with taurine

Bibliometric and Visual Analysis of Global Research on Taurine, Creatine, Carnosine, and Anserine with Metabolic Syndrome: From 1992 to 2022

Red meat and animal-sourced protein are often disparaged as risk factors for developing metabolic syndrome, while emerging research has shown the beneficial effects of dietary taurine, creatine, carnosine, and anserine which are all exclusively abundant in red meat. Thus, it is imperative to highlight the available evidence to help promote red meat as part of a well-balanced diet to optimize human health. In this study, a bibliometric analysis was conducted to investigate the current research status of dietary taurine, creatine, carnosine, and anserine with metabolic syndrome, identify research hotspots, and delineate developmental trends by utilizing the visualization software CiteSpace. A total of 1094 publications were retrieved via the Web of Science Core Collection from 1992 to 2022. There exists a gradual increase in the number of publications on this topic, but there is still much room for research papers to rise. The United States has participated in the most studies, followed by China and Japan. The University of Sao Paulo was the research institute contributing the most; Kyung Ja Chang and Sanya Roysommuti have been identified as the most prolific authors. The analysis of keywords reveals that obesity, lipid profiles, blood pressure, and glucose metabolism, as well as ergogenic aid and growth promoter have been the research hotspots. Inflammation and diabetic nephropathy will likely be frontiers of future research related to dietary taurine, creatine, carnosine, and anserine. Overall, this paper may provide insights for researchers to further delve into this field and enlist the greater community to re-evaluate the health effects of red meat.

An AMP Kinase-pathway dependent integrated stress response regulates ageing and longevity

The purpose of this article is to investigate the role of the AMP-kinase pathway (AMPK pathway) in the induction of a concomitant set of health benefits by exercise, numerous drugs, and health ingredients, all of which are adversely affected by ageing. Despite the AMPK pathway being frequently mentioned in relation to both these health effects and ageing, it appears challenging to understand how the activation of a single biochemical pathway by various treatments can produce such a diverse range of concurrent health benefits, involving so many organs. We discovered that the AMPK pathway functions as an integrated stress response system because of the presence of a feedback loop in it. This evolutionary conserved stress response system detects changes in AMP/ATP and NAD/NADH ratios, as well as the presence of potential toxins, and responds by activating a common protective transcriptional response that protects against aging and promotes longevity. The inactivation of the AMPK pathway with age most likely explains why ageing has a negative impact on the above-mentioned set of health benefits. We conclude that the presence of a feedback loop in the AMP-kinase pathway positions this pathway as an AMPK-ISR (AMP Kinase-dependent integrated stress response) system that responds to almost any type of (moderate) environmental stress by inducing various age-related health benefits and longevity.

Therapeutic Effects of Heterotrigona itama (Stingless Bee) Bee Bread in Improving Hepatic Lipid Metabolism through theActivation of the Keap1/Nrf2 Signaling Pathway in an Obese Rat Model

Bee bread (BB) has traditionally been used as a dietary supplement to treat liver problems. This study evaluated the therapeutic effects of Heterotrigona itama BB from Malaysia on obesity-induced hepatic lipid metabolism disorder via the regulation of the Keap1/Nrf2 pathway. Male Sprague Dawley rats were fed with either a normal diet or high-fat diet (HFD) for 6 weeks to induce obesity. Following 6 weeks, obese rats were treated either with distilled water (OB group), BB (0.5 g/kg body weight/day) (OB + BB group) or orlistat (10 mg/kg body weight/day) (OB + OR group) concurrent with HFD for another 6 weeks. BB treatment suppressed Keap1 and promoted Nrf2 cytoplasmic and nuclear translocations, leading to a reduction in oxidative stress, and promoted antioxidant enzyme activities in the liver. Furthermore, BB down-regulated lipid synthesis and its regulator levels (SIRT1, AMPK), and up-regulated fatty acid β-oxidation in the liver of obese rats, being consistent with alleviated lipid levels, improved hepatic histopathological changes (steatosis, hepatocellular hypertrophy, inflammation and glycogen expression) and prevented progression to non-alcoholic steatohepatitis. These results showed the therapeutic potentials of H. itama BB against oxidative stress and improved lipid metabolism in the liver of obese rats possibly by targeting the Keap1/Nrf2 pathway, hence proposing its role as a natural supplement capable of treating obesity-induced fatty liver disease.

Versatile Triad Alliance: Bile Acid, Taurine and Microbiota

Taurine is the most abundant free amino acid in the body, and is mainly derived from the diet, but can also be produced endogenously from cysteine. It plays multiple essential roles in the body, including development, energy production, osmoregulation, prevention of oxidative stress, and inflammation. Taurine is also crucial as a molecule used to conjugate bile acids (BAs). In the gastrointestinal tract, BAs deconjugation by enteric bacteria results in high levels of unconjugated BAs and free taurine. Depending on conjugation status and other bacterial modifications, BAs constitute a pool of related but highly diverse molecules, each with different properties concerning solubility and toxicity, capacity to activate or inhibit receptors of BAs, and direct and indirect impact on microbiota and the host, whereas free taurine has a largely protective impact on the host, serves as a source of energy for microbiota, regulates bacterial colonization and defends from pathogens. Several remarkable examples of the interaction between taurine and gut microbiota have recently been described. This review will introduce the necessary background information and lay out the latest discoveries in the interaction of the co-reliant triad of BAs, taurine, and microbiota.

Beneficial Effects of Taurine on Metabolic Parameters in Animals and Humans

Taurine (2-aminoethanesulfonic acid) is a non-essential amino acid mainly obtained through diet in humans. Despite the lack of research on the health effects of taurine in animals and humans, it is widely used as a dietary supplement. Evidence from human and animal studies indicates that taurine is involved in conjugation of bile acids and regulation of blood pressure and has anti-oxidative, anti-inflammatory, and anti-obesogenic properties. Taurine can benefit both human and non-human animal health in multiple ways. However, few interventional and epidemiological studies regarding the beneficial impacts of taurine in humans and other animals have been conducted. Here, we review the evidence from animal and human studies showing that taurine protects against dyslipidemia, obesity, hypertension, and diabetes mellitus.

Recent insights into the molecular regulators and mechanisms of taurine to modulate lipid metabolism: a review

Lipid metabolism disorders such as hypertriglyceridemia and hypercholesterolemia are risk factors for cardiovascular diseases and atherosclerosis that are grave public health issues. Taurine, a sulfur-containing non-essential amino acid exerts a wide range of physiological effects that regulate lipid metabolic disorders. Although the effects of taurine on lipid-lowering have been reported in animals and humans, mechanisms elucidating the lipid-lowering action of taurine remain unclear. A series of molecular regulators associated with lipid metabolism have been identified in the past few decades. These include nuclear receptors, transcription factors, and enzymes that undergo important changes during taurine treatment. In this review, we focus on the role of taurine in lipid metabolism and discuss taurine-related interventions in combating lipid disorders.

Activation of the Peroxisome Proliferator-Activated Receptors (PPAR-α/γ) and the Fatty Acid Metabolizing Enzyme Protein CPT1A by Camel Milk Treatment Counteracts the High-Fat Diet-Induced Nonalcoholic Fatty Liver Disease

Camel milk (CM) has a unique composition rich in antioxidants, trace elements, immunoglobulins, insulin, and insulin-like proteins. Treatment by CM demonstrated protective effects against nonalcoholic fatty liver disease (NAFLD) induced by a high-fat cholesterol-rich diet (HFD-C) in rats. CM dampened the steatosis, inflammation, and ballooning degeneration of the hepatocytes. It also counteracted hyperlipidemia, insulin resistance (IR), glucose intolerance, and oxidative stress. The commencement of NAFLD triggered the peroxisome proliferator-activated receptor-α (PPAR-α), carnitine palmitoyl-transferase-1 (CPT1A), and fatty acid-binding protein-1 (FABP1) and decreased the PPAR-γ expression in the tissues of the animals on HFD-C. This was associated with increased levels of the inflammatory cytokines IL-6 and TNF-α and leptin and declined levels of the anti-inflammatory adiponectin. Camel milk treatment to the NAFLD animals remarkably upregulated PPARs (α, γ) and the downstream enzyme CPT1A in the metabolically active tissues involved in cellular uptake and beta-oxidation of fatty acids. The enhanced lipid metabolism in the CM-treated animals was linked with decreased expression of FABP1 and suppression of IL-6, TNF-α, and leptin release with augmented adiponectin production. The protective effects of CM against the histological and biochemical features of NAFLD are at least in part related to the activation of the hepatic and extrahepatic PPARs (α, γ) with consequent activation of the downstream enzymes involved in fat metabolism. Camel milk treatment carries a promising therapeutic potential to NAFLD through stimulating PPARs actions on fat metabolism and glucose homeostasis. This can protect against hepatic steatosis, IR, and diabetes mellitus in high-risk obese patients.

Current innovations in nutraceuticals and functional foods for intervention of non-alcoholic fatty liver disease

As innovations in global agricultural production and food trading systems lead to major dietary shifts, high morbidity rates from non-alcoholic fatty liver disease (NAFLD), accompanied by elevated risk of lipid metabolism-related complications, has emerged as a growing problem worldwide. Treatment and prevention of NAFLD and chronic liver disease depends on the availability of safe, effective, and diverse therapeutic agents, the development of which is urgently needed. Supported by a growing body of evidence, considerable attention is now focused on interventional approaches that combines nutraceuticals and functional foods. In this review, we summarize the pathological progression of NAFLD and discuss the beneficial effects of nutraceuticals and the active ingredients in functional foods. We also describe the underlying mechanisms of these compounds in the intervention of NAFLD, including their effects on regulation of lipid homeostasis, activation of signaling pathways, and their role in gut microbial community dynamics and the gut-liver axis. In order to identify novel targets for treatment of lipid metabolism-related diseases, this work broadly explores the molecular mechanism linking nutraceuticals and functional foods, host physiology, and gut microbiota. Additionally, the limitations in existing knowledge and promising research areas for development of active interventions and treatments against NAFLD are discussed.

D-Pinitol Increases Insulin Secretion and Regulates Hepatic Lipid Metabolism in Msg-Obese Mice

D-pinitol is one of the major inositol found in plants and studies suggest its potential hypoglycemic and hypolipidemic actions in diabetic rodents. Here, we investigated the actions of D-pinitol on adiposity, and in lipid and glycemic homeostasis in monosodium glutamate (MSG)-obese mice. Swiss mice received daily subcutaneous injections of MSG [(4g/kg of body weight (BW)] or saline [1.25g/kg BW; control (CTL)] during their first five days of life. From 90-120 day-old, half of the MSG and CTL groups received 50 mg D-pinitol/kg BW/day (MPIN and CPIN groups) or vehicle (saline; MSG and CTL groups) by gavage. MSG mice displayed higher abdominal adiposity and hepatic triglycerides (TG) deposition, and increased hepatic expression of lipogenic genes (SREBP-1c, ACC-1 and FASN), but downregulation in AMPKα mRNA. MSG mice also exhibited hyperinsulinemia, islet hypersecretion and hypertrophy, glucose intolerance and insulin resistance. D-pinitol did not change adiposity, glucose intolerance, insulin resistance, but increased hepatic triglycerides (TG) content in MPIN mice, which was associated with increases in gene expressions of SREBP-1c and FASN, but reduction in AMPKα. Furthermore, D-pinitol enhanced insulin secretion in MPIN and CPIN groups. Therefore, D-pinitol enhanced glucose-induced insulin secretion, which may account to enhances hepatic lipogenesis and TG deposition in MPIN mice.

Effects of taurine on growth performance, antioxidant capacity, and lipid metabolism in broiler chickens

To investigate the effects of dietary taurine supplementation on growth performance, antioxidant status, and lipid metabolism in broilers, 384 male broilers (Arbor Acres, 1 D of age) were randomly allocated into 4 groups with 8 replicates of 8 birds. Dietary treatments were supplemented with taurine at the level of 0.00, 2.50, 5.00, and 7.50 g/kg of the diet (denoted as CON, TAU1, TAU2, TAU3, respectively). The BW gain from 1 to 21 D and from 22 to 42 D were all increased linearly (linear, P < 0.001) by taurine supplementation. Throughout the trial period, the highest BW gain and favorable gain-to-feed ratio were observed in the TAU2 group. Taurine supplementation increased the antioxidant enzyme activities and decreased (linear, P < 0.001) the content of malondialdehyde in both serum and the liver of broilers and alleviated oxidative damage through enhancing (P < 0.05) the hepatic genes expression of nuclear factor erythroid-2-related factor 2 (NRF2), glutathione peroxidase (GPX), and heme oxygenase-1 (HO-1). Correspondingly, in serum, the activities of hepatic lipase and total lipase were decreased linearly and quadratically (linear and quadratic, P < 0.001) with the increasing inclusion of taurine in the diet. Meanwhile, in serum, the content of triglycerides was significantly decreased (P < 0.05), and except for TAU3, the total cholesterol content was also significantly decreased (P < 0.05) by taurine supplementation. In addition, the hepatic content of triglycerides was significantly decreased (P < 0.05) in the TAU1 and TAU2 groups. Compared with the CON group, the hepatic genes expression of adenosine monophosphate-activated protein kinase alpha (AMPKα), silent 1, (SIRT1) and carnitine palmitoyltransferase 1 (CPT-1) were all increased (P < 0.05), and sterol regulatory element-binding protein-1 (SREBP-1) expression was decreased (P < 0.05) in the TAU2 group. These results indicated that taurine supplementation improved the growth performance, antioxidant capacity, and lipid metabolism of broilers.

Post-weaning exposure to high-sucrose diet induces early non-alcoholic fatty liver disease onset and progression in male mice: role of dysfunctional white adipose tissue

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome, ranging from simple steatosis to non-alcoholic steatohepatitis (NASH) particularly among chronic consumers of added sugar-rich diets. However, the impact of early consumption of such diets on NAFLD onset and progression is unclear. Thus, this study sought to characterise metabolic factors involved in NAFLD progression in young mice fed with a high-sucrose diet (HSD). Male Swiss mice were fed HSD or regular chow (CTR) from weaning for up to 60 or 90 days. Obesity development, glucose homeostasis and serum biochemical parameters were determined at each time-point. At day 90, mice were euthanised and white adipose tissue (WAT) collected for lipolytic function assessment and liver for histology, gene expression and cytokines quantification. At day 60, HSD mice presented increased body mass, hypertriglyceridemia, peripheral insulin resistance (IR) and simple steatosis. Upon 90 days on diet, WAT from HSD mice displayed impaired insulin sensitivity, which coincided with increased fasting levels of glucose and free fatty acids (FFA), as well as NAFLD progression to NASH. Transcriptional levels of lipogenic genes, particularly stearoyl-CoA desaturase-1, were consistently increased, leading to hepatic leukocyte infiltration and pro-inflammatory cytokines spillover. Therefore, our dataset supports IR triggering in the WAT as a major factor for dysfunctional release of FFA towards portal circulation and consequent upregulation of lipogenic genes and hepatic inflammatory onset, which decisively concurred for NAFLD-to-NASH progression in young HSD-fed mice. Notwithstanding, this study forewarns against the early introduction of dietary sugars in infant diet, particularly following breastfeeding cessation.

Taurine Supplementation Increases Post-Exercise Lipid Oxidation at Moderate Intensity in Fasted Healthy Males

Based on the fact that taurine can increase lipid metabolism, the objective of the present study was to evaluate the effects of different doses of acute taurine supplementation on lipid oxidation levels in healthy young men after a single bout of fasting aerobic exercise. A double-blind, acute, and crossover study design was conducted. Seventeen men (age 24.8 ± 4.07y; BMI: 23.9 ± 2.57 kg/m²) participated in the present study. Different doses of taurine (TAU) (3 g or 6 g) or placebo were supplemented 90 min before a single bout of fasting aerobic exercise (on a treadmill at 60% of VO₂ max). The subjects performed three trials, and each one was separated by seven days. Blood samples were collected at baseline and after the exercise protocol of each test to analyze plasma levels of glycerol and taurine. Lipid and carbohydrate oxidation were determined immediately after exercise for 15 min by indirect calorimetry. We observed that TAU supplementation (6 g) increased lipid oxidation (38%) and reduced the respiratory coefficient (4%) when compared to the placebo (p < 0.05). However, no differences in lipid oxidation were observed between the different doses of taurine (3 g and 6 g). For glycerol concentrations, there were no differences between trials. Six grams of TAU supplementation 90 min before a single bout of aerobic exercise in a fasted state was sufficient to increase the lipid oxidation post-exercise in healthy young men.

PPARs and the Development of Type 1 Diabetes

Peroxisome proliferator-activated receptors (PPARs) are a family of transcription factors with a key role in glucose and lipid metabolism. PPARs are expressed in many cell types including pancreatic beta cells and immune cells, where they regulate insulin secretion and T cell differentiation, respectively. Moreover, various PPAR agonists prevent diabetes in the non-obese diabetic (NOD) mouse model of type 1 diabetes. PPARs are thus of interest in type 1 diabetes (T1D) as they represent a novel approach targeting both the pancreas and the immune system. In this review, we examine the role of PPARs in immune responses and beta cell biology and their potential as targets for treatment of T1D.

Taurine supplementation in high-fat diet fed male mice attenuates endocrine pancreatic dysfunction in their male offspring

Obesity in fathers leads to DNA damage and epigenetic changes in sperm that may carry potential risk factors for metabolic diseases to the next generation. Taurine (TAU) supplementation has demonstrated benefits against testicular dysfunction and pancreatic islet impairments induced by obesity, but it is not known if these protective actions prevent the propagation of metabolic disruptions to the next generation; as such, we hypothesized that paternal obesity may increase the probability of endocrine pancreatic dysfunction in offspring, and that this could be prevented by TAU supplementation in male progenitors. To test this, male C57Bl/6 mice were fed on a control diet (CTL) or a high-fat diet (HFD) without or with 5% TAU in their drinking water (CTAU and HTAU) for 4 months. Subsequently, all groups of mice were mated with CTL females, and the F1 offspring were identified as: CTL-F1, CTAU-F1, HFD-F1, and HTAU-F1. HFD-fed mice were normoglycemic, but glucose intolerant and their islets hypersecreted insulin. However, at 90 days of age, HFD-F1 offspring displayed normal glucose homeostasis and adiposity, but reduced glucose-induced insulin release. HFD-F1 islets also exhibited β- and α-cell hypotrophy, and lower δ-cell number per islet. Paternal TAU supplementation prevented the decrease in glucose-induced insulin secretion and normalized β-cell size and δ-cell number, and increased α-cell size/islet in HTAU-F1 mice. In conclusion, HFD consumption by male founders decreases β-cell secretion and islet-cell distribution in their offspring. TAU attenuates the deleterious effects of paternal obesity on insulin secretion and islet-cell morphology in F1 offspring.

Preventive or Curative Administration of Taurine Regulates Lipid Metabolism in the Liver of Rats with Alcoholic Liver Disease

Excessive consumption causes alcoholic liver disease (ALD), which injures hepatocytes and induces imbalance of lipid metabolism. Taurine is known to protect the liver from various liver injuries, and relieve lipid profile. Our previous studies also found that taurine can prevent or cure ALD, reduce fat deposition, but the mechanism remains unclear. In the present study, ALD rat model was established by administration of alcohol, pyrazole and high fat diet. Two percent taurine was administered at the same time or after ALD model establishment. Serum activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), serum and hepatic TC, TG, HDL-C and LDL-C were analyzed. Real-Time RT-PCR was conducted to detect the mRNA expressions of fatty acid synthetase (FAS), acetyl-CoA catboxylase (ACC), carnitine palmitoyl transferase 1 (CPT-1), 3-Hydroxy-3-methyl glutaric acid acyl Coenzyme A reductase (HMGCR), peroxisome proliferators activated receptor α (PPARα) and sterol regulatory element-binding protein 1c (SREBP-1c). The results showed that serum ALT, AST, serum and hepatic TC, TG and LDL-C were higher, while HDL-C in ALD model rats was lower than normal rats, the changes of which can be significantly relieved by taurine administration. mRNA expressions of ACC, FAS, CPT-1, HMGCR, PPARα and SREBP-1c which were significantly changed by ethanol can also be regulated by taurine. The results indicated that taurine can prevent and repair hepatic injury of ALD rats and balance lipid metabolism indexes in the liver, the mechanisms may involves in the regulation of related enzymes and transcriptional regulators participated in lipid metabolism.

Regulation of glucose and lipid metabolism by the pancreatic and extra-pancreatic actions of taurine

The beneficial actions of L-taurine (Tau) against glucose intolerance, obesity, type 2 diabetes (T2D), and non-alcoholic fat liver disease (NAFLD) have been linked to its antioxidant and anti-inflammatory effects, which ameliorate tissue insulin sensitivity. Importantly, there are several lines of evidence that indicate a direct action of Tau on the endocrine pancreas to regulate the secretion and paracrine actions of insulin, glucagon, and somatostatin. Furthermore, Tau can also ameliorate glucose metabolism through the enhancement of insulin signaling. However, some of the benefits of Tau upon intermediary metabolism may manifest via considerable antagonism of the action of insulin. Therefore, this review discusses the mechanisms of action by which Tau may regulate endocrine pancreatic morphofunction, and glucose and lipid homeostasis.

Taurine attenuates the development of hepatic steatosis through the inhibition of oxidative stress in a model of nonalcoholic fatty liver disease in vivo and in vitro

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease. It is characterized by the accumulation of triglyceride within hepatocytes. Taurine is a sulfur-containing-β-amino acid that is widely distributed in mammalian tissues. The objective of this study was to examine the effects of taurine on the development of hepatic steatosis in a model of NAFLD in vivo and in vitro. Male C57BL/6J mice were fed a high-fat diet (HFD) supplemented with 2% (w/v) or 5% (w/v) taurine for 12 weeks. An in vitro study was performed in HepG2 cells loaded with fatty acids. Twelve weeks of supplementation with an HFD increased the hepatic lipid levels and oxidative stress as well as the body weight and liver weight. Taurine significantly suppressed these changes, which was accompanied by a decrease in the hepatic level of thiobarbituric acid-reactive substances (TBARS). In addition, taurine treatment suppressed the HFD-induced reduction of the enzyme activity of hepatic superoxide dismutase and catalase and the reduction of the hepatic level of reduced glutathione and ATP. In HepG2 cells, taurine suppressed the fatty acid-induced lipid accumulation, production of reactive oxygen species and TBARS level, and amelioration of the fatty acid-induced disruption of the mitochondrial membrane potential. These results showed that taurine was effective in alleviating hepatic steatosis by reducing oxidative stress. Taurine may, therefore, be of therapeutic value in reducing the risks associated with NAFLD.

Duodeno-jejunal bypass restores β-cell hypersecretion and islet hypertrophy in western diet obese rats

PURPOSE

Duodeno-jejunal bypass (DJB) operation improves glucose homeostasis in morbid obesity, independently of weight loss or reductions in adiposity, through mechanisms not yet fully elucidated. Herein, we evaluated the effects of DJB upon glucose homeostasis, endocrine pancreatic morphology, and β-cell responsiveness to potentiating agents of cholinergic and cAMP pathways, in western diet (WD) obese rats, at 2 months after operation.

METHODS

From 8 to 18 weeks of age male Wistar rats fed on a WD. After this period, a sham (WD Sham group) or DJB (WD DJB) operations were performed. At 2 months after operation glucose homeostasis was verified.

RESULTS

Body weight was similar between WD DJB and WD Sham rats, but WD DJB rats showed a decrease in Lee index, retroperitoneal and perigonadal fat pads. Also, WD DJB rats displayed reduced fasting glycemia and insulinemia, and increased insulin-induced Akt activation in the gastrocnemius. Islets from WD DJB rats secreted less amounts of insulin, in response to activators of the cholinergic (carbachol and phorbol 12-myristate 13-acetate) and cAMP (forskolin and 3-isobutyl-1-methyl-xantine) pathways. Islets of WD DJB rats had higher sintaxin-1 protein content than WD Sham, but without modification in muscarinic-3 receptor, protein kinase (PK)-Cα, and (PK)-Aα protein amounts. In addition, islets of WD DJB animals showed reduction in islets and β-cell masses.

CONCLUSION

DJB surgery improves fasting glycemia and insulin action in skeletal muscle. Better endocrine pancreatic morphofunction was associated, at least in part, with the regulation of the cholinergic and cAMP pathways, and improvements in syntaxin-1 islet protein content induced by DJB.

Randomised clinical study: the effects of oral taurine 6g/day vs placebo on portal hypertension

BACKGROUND

The amino sulphonic acid taurine reduces oxidative endoplasmatic reticulum stress and inhibits hepatic stellate cell activation, which might lead to reduction of portal pressure in cirrhosis.

AIM

To assess the haemodynamic effects of taurine supplementation in patients with cirrhosis and varices.

METHODS

Patients with hepatic venous pressure gradient (HVPG) ≥12 mm Hg were included in this prospective proof of concept study. Concomitant nonselective beta-blockers therapy was not allowed. Patients received either 4 weeks of oral taurine (6 g/day), or placebo, prior to evaluation of HVPG response.

RESULTS

Thirty patients were screened and 22 included in the efficacy analysis (12 taurine/10 placebo; 64% male, mean age: 52 ± 11 years, Child A: 9%, B:64%, C:27%, ascites:68%). In the taurine group, mean HVPG dropped from 20 mm Hg (±4) at baseline to 18 mm Hg (±4) on day 28 (mean relative change: -12%, P = .0093). In the placebo group, mean HVPG increased from 20 mm Hg (±5) at baseline to 21 mm Hg (±5) on day 28 (mean relative change:+2%, P = .4945). Taurine had no significant effects on systemic haemodynamics. Seven of 12 patients (58%) on taurine achieved a HVPG response >10%, compared to none in the placebo group (P = .0053). In a multivariate linear model, HVPG reduction was significantly larger in the taurine group compared to placebo group (P = .0091 and P = .0109 for absolute and relative change respectively). Treatment-related adverse events included gastrointestinal discomfort and fatigue, and were usually mild and comparable between treatment groups.

CONCLUSION

Taurine is safe and may reduce portal pressure in cirrhotic patients. More studies on the underlying mechanisms of action and long-term effects of taurine supplementation are warranted.

Diet-induced glucose homeostasis dysregulation is enhanced by taurine supplementation in ovariectomized mice

Low levels of estrogens are associated with obesity-related comorbidities. Mice with lower levels of estrogens are thereby more sensitive to the effects of a high-fat-diet (HFD) for the development of glucose intolerance and insulin resistance. Studies in vivo have demonstrated that taurine (TAU) supplementation prevents glucose and insulin resistance. Thus, we aimed to investigate the potential beneficial effects of TAU supplementation on glucose homeostasis of mice with low levels of estrogens fed with a HFD. 3-month-old female C57BL/6J mice underwent bilateral ovariectomy (OVX). After 1 week of recovery, mice were divided into 4 groups and either received: a standard chow diet (OVXC), chow diet plus drinking water enriched with 3% of TAU (OVXCT), HFD (OVXH), and HFD plus supplementation of TAU (OVXHT) for 14 weeks. Exposure to the HFD increased adiposity and plasma levels of glucose and insulin. Contrary to our prediction, the addition of TAU enhanced the deleterious effects of the HFD. Glucose and insulin tolerance tests (ipGTT and ipITT) indicated that mice maintained on the HFD + TAU had worse glucose intolerance and insulin resistance that was linked to lower insulin signaling in skeletal muscle and liver. Insulin secretion of isolated pancreatic islets of OVXH mice was higher than OVXC, and the addition of TAU associated with a HFD did not modulate insulin secretion, suggesting a failure of pancreatic β cells of OVXHT mice. These results suggest that despite the beneficial reports of TAU, it should be used cautiously in situations where the levels of estrogens are low.

Nutrition Supplements to Stimulate Lipolysis: A Review in Relation to Endurance Exercise Capacity

Athletes make great efforts to increase their endurance capacity in many ways. Using nutrition supplements for stimulating lipolysis is one such strategy to improve endurance performance. These supplements contain certain ingredients that affect fat metabolism; furthermore, in combination with endurance training, they tend to have additive effects. A large body of scientific evidence shows that nutrition supplements increase fat metabolism; however, the usefulness of lipolytic supplements as ergogenic functional foods remains controversial. The present review will describe the effectiveness of lipolytic supplements in fat metabolism and as an ergogenic aid for increasing endurance exercise capacity. There are a number of lipolytic supplements available on the market, but this review focuses on natural ingredients such as caffeine, green tea extract, L-carnitine, Garcinia cambogia (hydroxycitric acid), capsaicin, ginseng, taurine, silk peptides and octacosanol, all of which have shown scientific evidence of enhancing fat metabolism associated with improving endurance performance. We excluded some other supplements owing to lack of data on fat metabolism or endurance capacity. Based on the data in this review, we suggest that a caffeine and green tea extract improves endurance performance and enhances fat oxidation. Regarding other supplements, the data on their practical implications needs to be gathered, especially for athletes.

Duodenal-jejunal bypass normalizes pancreatic islet proliferation rate and function but not hepatic steatosis in hypothalamic obese rats

Modifications in life-style and/or pharmacotherapies contribute to weight loss and ameliorate the metabolic profile of diet-induced obese humans and rodents. Since these strategies fail to treat hypothalamic obesity, we have assessed the possible mechanisms by which duodenal-jejunal bypass (DJB) surgery regulates hepatic lipid metabolism and the morphophysiology of pancreatic islets, in hypothalamic obese (HyO) rats. During the first 5 days of life, male Wistar rats received subcutaneous injections of monosodium glutamate (4 g/kg body weight, HyO group), or saline (CTL). At 90 days of age, HyO rats were randomly subjected to DJB (HyO DJB group) or sham surgery (HyO Sham group). HyO Sham rats were morbidly obese, insulin resistant, hypertriglyceridemic and displayed higher serum concentrations of non-esterified fatty acids (NEFA) and hepatic triglyceride (TG). These effects were associated with higher expressions of the lipogenic genes and fatty acid synthase (FASN) protein content in the liver. Furthermore, hepatic genes involved in β-oxidation and TG export were down-regulated in HyO rats. In addition, these rats exhibited hyperinsulinemia, β-cell hypersecretion, a higher percentage of islets and β-cell area/pancreas section, and enhanced nuclear content of Ki67 protein in islet-cells. At 2 months after DJB surgery, serum concentrations of TG and NEFA, but not hepatic TG accumulation and gene and protein expressions, were normalized in HyO rats. Insulin release and Ki67 positive cells were also normalized in HyO DJB islets. In conclusion, DJB decreased islet-cell proliferation, normalized insulinemia, and ameliorated insulin sensitivity and plasma lipid profile, independently of changes in hepatic metabolism.

Taurine Treatment Modulates Circadian Rhythms in Mice Fed A High Fat Diet

Close ties have been made among certain nutrients, obesity, type 2 diabetes and circadian clocks. Among nutrients, taurine has been documented as being effective against obesity and type 2 diabetes. However, the impact of taurine on circadian clocks has not been elucidated. We investigated whether taurine can modulate or correct disturbances in daily rhythms caused by a high-fat diet in mice. Male C57BL/6 mice were divided in four groups: control (C), control + taurine (C+T), high-fat diet (HFD) and HFD + taurine (HFD+T). They were administered 2% taurine in their drinking water for 10 weeks. Mice were euthanized at 6:00, 12:00, 18:00, and 24:00. HFD mice increased body weight, visceral fat and food intake, as well as higher levels of glucose, insulin and leptin, throughout the 24 h. Taurine prevented increments in food intake, body weight and visceral fat, improved glucose tolerance and insulin sensitivity and reduced disturbances in the 24 h patterns of plasma insulin and leptin. HFD downregulated the expression of clock genes Rev-erbα, Bmal1, and Per1 in pancreatic islets. Taurine normalized the gene and protein expression of PER1 in beta-cells, which suggests that it could be beneficial for the correction of daily rhythms and the amelioration of obesity and diabetes.

Prepartum body condition score and plane of nutrition affect the hepatic transcriptome during the transition period in grazing dairy cows

Background

A transcriptomic approach was used to evaluate potential interactions between prepartum body condition score (BCS) and feeding management in the weeks before calving on hepatic metabolism during the periparturient period.

Methods

Thirty-two mid-lactation grazing dairy cows of mixed age and breed were randomly allocated to one of four treatment groups in a 2 × 2 factorial arrangement: two prepartum BCS categories [4.0 (thin, BCS4) and 5.0 (optimal, BCS5); based on a 10-point scale], and two levels of energy intake during the 3 weeks preceding calving (75 and 125 % of estimated requirements). Liver samples were obtained at −7, 7, and 28 d relative to parturition and subsequent RNA was hybridized to the Agilent 44 K Bovine (V2) Microarray chip. The Dynamic Impact Approach was used for pathway analysis, and Ingenuity Pathway Analysis was used for gene network analysis.

Results

The greater number of differentially expressed genes in BCS4 cows in response to prepartum feed allowance (1071 vs 310, over the entire transition period) indicates that these animals were more responsive to prepartum nutrition management than optimally-conditioned cows. However, independent of prepartum BCS, pathway analysis revealed that prepartal feeding level had a marked effect on carbohydrate, amino acid, lipid, and glycan metabolism. Altered carbohydrate and amino acid metabolism suggest a greater and more prolonged negative energy balance postpartum in BCS5 cows overfed prepartum. This is supported by opposite effects of prepartum feeding in BCS4 compared with BCS5 cows in pathways encompassing amino acid, vitamin, and co-factor metabolism. The prepartum feed restriction ameliorates the metabolic adaptation to the onset of lactation in BCS5 cows, while detrimentally affecting BCS4 cows, which seem to better adapt when overfed. Alterations in the glycosaminoglycans synthesis pathway support this idea, indicating better hepatic health status in feed-restricted BCS5 and overfed BCS4 cows. Furthermore, IPA network analysis suggests liver damage in feed-restricted thin cows, likely due to metabolic overload.

Conclusion

Overall, the data support the hypothesis that overfeeding in late-pregnancy should be limited to underconditioned cows, while cows with optimal degree of body condition should be maintained on an energy-restricted diet.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-3191-3) contains supplementary material, which is available to authorized users.

Short Exposure to a High-Sucrose Diet and the First 'Hit' of Nonalcoholic Fatty Liver Disease in Mice

High-sucrose and high-fat diets induce deregulation in the metabolism of lipids and carbohydrates. This study aimed to detect the initial consequences on lipogenesis, gluconeogenesis and insulin signaling in the livers of rodents fed high-fat and/or high-sucrose diets for a short period of time. Male mice received a standard chow (SC), high-fat (HF), high-sucrose (HSu) or high-fat, high-sucrose (HFHSu) diet for 4 weeks. At euthanasia, blood was collected and the liver was removed for histomorphometrical and molecular analysis. The HF, HSu and HFHSu groups presented glucose intolerance, hepatomegaly, liver steatosis and lipid profile alteration when compared to the SC group (p < 0.0005). Additionally, there was an elevation in protein levels involved in lipogenesis (SREBP-1c), gluconeogenesis (PEPCK and G6Pase) and insulin signaling (IRS-1 and Akt) in the livers from the experimental groups compared to the SC group (p < 0.0005). Thus, we conclude that a short-term HF and/or HSu diet promotes glucose intolerance and liver damage in adult male mice. Surprisingly, the short exposure to excess sucrose in the diet promoted glucose intolerance and liver damage even in the absence of an increase in body mass or changes in serum insulin, cholesterol and triacylglycerol levels.

Bile Acid Modifications at the Microbe-Host Interface: Potential for Nutraceutical and Pharmaceutical Interventions in Host Health

Bile acids have emerged as important signaling molecules in the host, as they interact either locally or systemically with specific cellular receptors, in particular the farnesoid X receptor (FXR) and TGR5. These signaling functions influence systemic lipid and cholesterol metabolism, energy metabolism, immune homeostasis, and intestinal electrolyte balance. Through defined enzymatic activities, the gut microbiota can significantly modify the signaling properties of bile acids and therefore can have an impact upon host health. Alterations to the gut microbiota that influence bile acid metabolism are associated with metabolic disease, obesity, diarrhea, inflammatory bowel disease (IBD), Clostridium difficile infection, colorectal cancer, and hepatocellular carcinoma. Here, we examine the regulation of this gut-microbiota-liver axis in the context of bile acid metabolism and indicate how this pathway represents an important target for the development of new nutraceutical (diet and/or probiotics) and targeted pharmaceutical interventions.

Chronic Glucocorticoid-Rich Milieu and Liver Dysfunction

We investigated the impact of chronic hypercorticosteronemia (due to neonatal monosodium L-glutamate, MSG, and treatment) on liver oxidative stress (OS), inflammation, and carbohydrate/lipid metabolism in adult male rats. We evaluated the peripheral concentrations of several metabolic and OS markers and insulin resistance indexes. In liver we assessed (a) OS (GSH and protein carbonyl groups) and inflammatory (IL-1b, TNFa, and PAI-1) biomarkers and (b) carbohydrate and lipid metabolisms. MSG rats displayed degenerated optic nerves, hypophagia, low body and liver weights, and enlarged adipose tissue mass; higher peripheral levels of glucose, triglycerides, insulin, uric acid, leptin, corticosterone, transaminases and TBARS, and peripheral and liver insulin resistance; elevated liver OS, inflammation markers, and glucokinase (mRNA/activity) and fructokinase (mRNA). Additionally, MSG liver phosphofructokinase-2, glucose-6-phosphatase (mRNA and activity) and glucose-6-phosphate dehydrogenase, Chrebp, Srebp1c, fatty acid synthase, and glycerol-3-phosphate (mRNAs) were increased. In conclusion adult MSG rats developed an insulin-resistant state and increased OS and serious hepatic dysfunction characterized by inflammation and metabolic signs suggesting increased lipogenesis. These features, shared by both metabolic and Cushing's syndrome human phenotypes, support that a chronic glucocorticoid-rich endogenous environment mainly impacts on hepatic glucose cycle, displacing local metabolism to lipogenesis. Whether correcting the glucocorticoid-rich environment ameliorates such dysfunctions requires further investigation.

Hypothalamic Obesity in Craniopharyngioma Patients: Disturbed Energy Homeostasis Related to Extent of Hypothalamic Damage and Its Implication for Obesity Intervention

Hypothalamic obesity (HO) occurs in patients with tumors and lesions in the medial hypothalamic region. Hypothalamic dysfunction can lead to hyperinsulinemia and leptin resistance. This review is focused on HO caused by craniopharyngiomas (CP), which are the most common childhood brain tumors of nonglial origin. Despite excellent overall survival rates, CP patients have substantially reduced quality of life because of significant long-term sequelae, notably severe obesity in about 50% of patients, leading to a high rate of cardiovascular mortality. Recent studies reported that both hyperphagia and decreased energy expenditure can contribute to severe obesity in HO patients. Recognized risk factors for severe obesity include large hypothalamic tumors or lesions affecting several medial and posterior hypothalamic nuclei that impact satiety signaling pathways. Structural damage in these nuclei often lead to hyperphagia, rapid weight gain, central insulin and leptin resistance, decreased sympathetic activity, low energy expenditure, and increased energy storage in adipose tissue. To date, most efforts to treat HO have shown disappointing long-term success rates. However, treatments based on the distinct pathophysiology of disturbed energy homeostasis related to CP may offer options for successful interventions in the future.