Ursodeoxycholic acid ameliorates fructose-induced metabolic syndrome in rats

Natural products as pharmacological modulators of mitochondrial dysfunctions for the treatment of diabetes and its complications: An update since 2010

Diabetes, characterized as a well-known chronic metabolic syndrome, with its associated complications pose a substantial and escalating health and healthcare challenge on a global scale. Current strategies addressing diabetes are mainly symptomatic and there are fewer available curative pharmaceuticals for diabetic complications. Thus, there is an urgent need to identify novel pharmacological targets and agents. The impaired mitochondria have been associated with the etiology of diabetes and its complications, and the intervention of mitochondrial dysfunction represents an attractive breakthrough point for the treatments of diabetes and its complications. Natural products (NPs), with multicenter characteristics, multi-pharmacological activities and lower toxicity, have been caught attentions as the modulators of mitochondrial functions in the therapeutical filed of diabetes and its complications. This review mainly summarizes the recent progresses on the potential of 39 NPs and 2 plant-extracted mixtures to improve mitochondrial dysfunction against diabetes and its complications. It is expected that this work may be useful to accelerate the development of innovative drugs originated from NPs and improve upcoming therapeutics in diabetes and its complications.

Geraniin Ameliorates Hypertensive Vascular Remodelling in a Diet-Induced Obese Animal Model through Antioxidant and Anti-Inflammatory Effects

Geraniin, an ellagitannin, has shown a potent blood pressure-lowering effect in vivo. Therefore, this study aims to further characterize the ability of geraniin to attenuate hypertensive vascular dysfunction, a key feature of cardiovascular disease (CVD) development. Hypertension was induced in male Sprague-Dawley rats through feeding a high-fat diet (HFD) for eight weeks, followed by oral administration of 25 mg/kg/day geraniin for four weeks. The parameters of vascular dysfunction such as the structure and function of blood vessels as well as the vascular oxidative stress and inflammation were evaluated. The outcomes of geraniin-treated rats were compared with those of untreated rats on either a normal diet (ND) or HFD and with HFD-fed rats treated with captopril (40 mg/kg/day). We found that geraniin supplementation effectively ameliorated HFD-induced hypertension and abnormal remodelling of the thoracic aorta by suppressing excessive vascular superoxide (O₂^-) radical generation and overexpression of pro-inflammatory mediators in the circulating leukocytes. Furthermore, compared to the ND-fed rats, geraniin also independently promoted the significant enlargement of the thoracic aortic lumen for blood pressure reduction. Notably, the vascular benefits of geraniin were comparable to that of captopril. Collectively, these data suggest that geraniin can mitigate hypertensive vascular remodelling caused by overnutrition, which potentially abrogates the further development of CVDs.

Outcomes of Pregnancies in Liver Transplant Recipients: Experience of a Single Center in Turkey

BACKGROUND

Liver transplantation is the ultimate treatment for end-stage liver failure. As organ donation systems improve, more reproductive-age women are expected to undergo liver transplantation. Current studies indicate increased risk of some perinatal and maternal complications; however, the available data is still scarce. Therefore, we aimed to evaluate the maternal and fetal outcomes of pregnancies in liver transplant recipients.

METHODS

We retrospectively evaluated liver transplantations performed between 2011 and 2020 in a tertiary center. Perinatal, maternal, fetal outcomes and transplant status were assessed among pregnancies conceived after liver transplantation.

RESULTS

Among 1137 patients, 82 (7.2%) were reproductive-age females. Ten pregnancies in nine patients were identified after liver transplantation. The mean age of patients was 29.3±6.1 at transplantation, and 32.5±5.4 at conception. The mean interval between conception and transplantation was 30.3±11.7 months. There were eight live births (80%), one miscarriage (10%) and one termination (10%). Three patients delivered<37th gestational week (37.5%). The median gestational age at birth was 38.5 (IQR: 5.21) weeks. The mean birth weight of infants was 2669.3±831 g. Two patients were diagnosed with preeclampsia (25%) and acute graft rejection episode was observed in one patient (10%) during pregnancy.

CONCLUSION

Although the incidence of some perinatal complications, such as hypertensive disorders and preterm delivery, is increased in liver transplant recipients, pregnancy after liver transplantation appears to have favorable outcomes for the mother, fetus and transplant with close monitoring by a multidisciplinary team.

Effects of High-Fructose Corn Syrup Intake on Glucocorticoid Metabolism in Rats During Childhood, Adolescence and Adulthood

The consumption of high-fructose corn syrup (HFCS) has been increasing in recent decades, especially among children. Some reports suggest that children and adolescents are more sensitive to the adverse effects of fructose intake than adults. However, the underlying mechanism of the difference in vulnerability between adolescence and adulthood have not yet been elucidated. In this study, we attempted to elucidate the different effects of HFCS intake at different growth stages in rats: childhood and adolescence (postnatal day (PD) 21–60), young adulthood (PD60–100), and adulthood (PD100–140). Since alterations in hepatic glucocorticoid (GC) metabolism can cause diseases including insulin resistance, we focused on GC metabolizing enzymes such as 11 beta-hydroxysteroid dehydrogenase 1 and 2 (Hsd11b1 and Hsd11b2) and steroid 5 alpha-reductase 1 (Srd5a1). Western blotting showed an increase in Hsd11b1 expression and a decrease in Hsd11b2 expression in childhood and adolescence but not in adulthood. We also observed changes in Hsd11b1 and Hsd11b2 activities only in childhood and adolescence, consistent with the results of mRNA and protein expression analysis. The effect of high-fructose intake with regards to GC metabolism may therefore vary with developmental stage. This study provides insight into the adverse effects of fructose on GC metabolism in children in the context of increasing rates of HFCS consumption.

Dietary Supplementation with D-Ribose-L-Cysteine Prevents Hepatic Stress and Pro-Inflammatory Responses in Male Wistar Rats Fed a High-Fructose High-Fat Diet

Diets rich in fats and fructose are associated with the pathogenesis of oxidative stress-induced non-alcoholic fatty liver disease. Therefore, we investigated the effect of D-ribose-L-cysteine (DRLC) in high-fructose high-fat (HFHF) diet-fed rats. Twenty rats (n = 5), divided into four groups, were simultaneously exposed to HFHF and/or DRLC (250 mg/kg) orally during the 8 weeks of the study. Results showed that HFHF precipitated pro-inflammation and selective disruption of the oxidative stress markers. There were significant decreases in the level of antioxidants such as superoxide dismutase (SOD), glutathione peroxidase (GPX), total antioxidant capacity (TAC), hepatic SOD and GPX. Significant increases in serum levels of uric acid (UA), tumour necrosis factor-alpha (TNF-α), C-reactive protein (CRP) and hepatic Xanthine oxidase (XO) were observed in the HFHF compared to the control. In the HFHF + DRLC group, oxidative stress was mitigated due to differences in serum levels of SOD, GPX, TAC, TNF-α, liver SOD, and XO relative to control. The administration of DRLC alone caused significant reductions in malondialdehyde, UA and CRP and a significant increase in SOD compared to the control. DRLC prevents hepatic and systemic oxidative stress and pro-inflammatory events in HFHF diet-fed rats.

Renal Farnesoid X Receptor improves high fructose-induced salt-sensitive hypertension in mice by inhibiting DNM3 to promote nitro oxide production

OBJECTIVE

Farnesoid X Receptor (FXR) is highly expressed in renal tubules, activation of which attenuates renal injury by suppressing inflammation and fibrosis. However, whether renal FXR contributes to the regulation of blood pressure (BP) is poorly understood. This study aimed to investigate the anti-hypertensive effect of renal FXR on high-fructose-induced salt-sensitive hypertension and underlying mechanism.

METHODS

Hypertension was induced in male C57BL/6 mice by 20% fructose in drinking water with 4% sodium chloride in diet (HFS) for 8 weeks. The effects of FXR on NO production were estimated in vitro and in vivo.

RESULTS

Compared with control, HFS intake elevated BP, enhanced renal injury and reduced renal NO levels as well as FXR expression in the kidney of mice. In the mouse renal collecting duct cells mIMCD-K2, FXR agonists promoted NO production by enhancing the expression of neuronal nitric oxide synthase (nNOS) and inducible nitric oxide synthase (iNOS), whereas this effect was diminished by fxr knockdown. We further found that Dynamin 3 (DNM3), a binding protein with nNOS in the renal medulla, was inhibited by FXR and its deficiency elevated NO production in mIMCD-K2 cells. In HFS-fed mice, renal fxr overexpression significantly attenuated hypertension and renal fibrosis, regulated the expression of DNM3/nNOS/iNOS, and increased renal NO levels.

CONCLUSION

Our results demonstrated that renal FXR prevents HFS-induced hypertension by inhibiting DNM3 to promote NO production. These findings provide insights into the role and potential mechanism of renal FXR for the treatment of hypertension.

Metabolic Syndrome: Lessons from Rodent and Drosophila Models

Overweight and obesity are health conditions tightly related to a number of metabolic complications collectively called “metabolic syndrome” (MetS). Clinical diagnosis of MetS includes the presence of the increased waist circumference or so-called abdominal obesity, reduced high density lipoprotein level, elevated blood pressure, and increased blood glucose and triacylglyceride levels. Different approaches, including diet-induced and genetically induced animal models, have been developed to study MetS pathogenesis and underlying mechanisms. Studies of metabolic disturbances in the fruit fly Drosophila and mammalian models along with humans have demonstrated that fruit flies and small mammalian models like rats and mice have many similarities with humans in basic metabolic functions and share many molecular mechanisms which regulate these metabolic processes. In this paper, we describe diet-induced, chemically and genetically induced animal models of the MetS. The advantages and limitations of rodent and Drosophila models of MetS and obesity are also analyzed.

Moderation of gut microbiota and bile acid metabolism by chlorogenic acid improves high-fructose-induced salt-sensitive hypertension in mice

Chlorogenic acid (CGA) is a natural compound with many important pharmacological effects including anti-hypertension. This study aimed to investigate the anti-hypertensive effect of CGA on high-fructose-induced salt-sensitive hypertension and the underlying mechanism. Hypertension was induced in male C57BL/6 mice by 20% fructose in drinking water plus 4% sodium chloride in the diet (HFS) for 8 weeks. CGA (50, 100 or 200 mg kg^-1 d^-1) was orally administered to HFS-treated mice. The blood pressure of mice was recorded via the tail cuff method. The structure of gut microbiota and profiles of bile acids (BAs) in the serum were determined. Here, we found that HFS-elevated systolic blood pressure was greatly attenuated by CGA. The microbiota analysis showed that CGA restructured the HFS-treated gut microbiota, and markedly enriched Klebsiella. Oral administration of a Klebsiella isolate, Klebsiella oxytoca, also exhibited an anti-hypertensive effect in HFS-fed mice. Furthermore, we found that CGA and CGA-enriched K. oxytoca enhanced the expression of colonic Farnesoid X Receptor (FXR), modulated BA metabolism and enriched some BAs including deoxycholic acid (DCA) in the serum of HFS-fed mice. Treatment with DCA improved phenylephrine-induced vasoconstriction in arterioles of mice and attenuated hypertension in HFS-fed mice, suggesting that DCA serves as a link between gut microbiota and blood pressure. Our results clearly demonstrate that CGA attenuates HFS-induced hypertension in mice by modulating gut microbiota and BA metabolism. These findings provide insights into the potential mechanism of CGA for the treatment of hypertension.

Gut microbiota as the critical correlation of polycystic ovary syndrome and type 2 diabetes mellitus

Gut microbiota forms a symbiotic relationship with the host and maintains the ecological balance of the internal and external environment of the human body. However, dysbiosis of the gut microbiota and immune deficiency, as well as environmental changes, can destroy the host-microbial balance, leading to the occurrence of a variety of diseases, such as polycystic ovary syndrome (PCOS), type 2 diabetes mellitus (T2DM), and obesity. Meanwhile, diseases can also affect gut microbiota, forming a vicious cycle. The role of the intestinal microbiota in different diseases have been proven by several studies; however, as a common target of PCOS and T2DM, there are few reports on the treatment of different diseases through the regulation of intestinal microbiota as the critical correlation. This review analyzed the common mechanisms of intestinal microbiota in PCOS and T2DM, including the dysbiosis of gut microbiota, endotoxemia, short-chain fatty acids, biotransformation of bile acids, and synthesis of amino acid in regulating insulin resistance, obesity, chronic inflammation, and mitochondrial dysfunction. The possible therapeutic effects of probiotics and/or prebiotics, fecal microbiota transplantation, bariatric surgery, dietary intervention, drug treatment, and other treatments targeted at regulating intestinal microbiota were also elucidated.

D-ribose-L-cysteine prevents oxidative stress and cardiometabolic syndrome in high fructose high fat diet fed rats

Cardiometabolic syndrome has been linked with dietary modification. Therefore, we investigated the effects of D-ribose-L-cysteine (DRLC) in rats fed with high fructose high fat (HFHF) diet. Twenty rats (n = 5), divided into 4 groups were concurrently exposed to HFHF and/or DRLC (250 mg/kg, p.o) during the 8 weeks study. The result showed that compared to control group, HFHF group had significant impairment in lipid and glucose homeostasis, increased cardiac xanthine oxidase, systolic blood pressure, heart rate, %body weight change and fluid intake. Also, there were significant reductions in HDL-C, cardiac (GPX, NO&GGT), feed intake and relative heart weight in the latter, relative to the former. However, there were no significant differences in most of the observed physical and biochemical changes in HFHF + DRLC group compared to control. DRLC alone did not disrupt the level of biomarkers. Conclusively, DRLC prevented the manifestation of oxidative stress and cardiometabolic syndrome in HFHF-diet fed rats.

Aqueous extract of large cardamom inhibits vascular damage, oxidative stress, and metabolic changes in fructose-fed hypertensive rats

PURPOSE

Since metabolic abnormalities such as elevated glucose level and imbalanced lipid profiles increase the risk for hypertension and cause endothelial dysfunction, we evaluated the effect of aqueous extract of large cardamom (AELC) on fructose-induced metabolic hypertension and oxidative stress.

METHODS

The male Sprague-Dawley rats were divided into 6 groups with 5 rats in each group, and each group was fed with 10% fructose in drinking water for 8 weeks. Starting from week 5, animals were treated with 50, 100, and 200 mg/kg/day AELC or Losartan (10 mg/kg/day). Systolic, diastolic, and mean arterial blood pressure was measured once in every seven days using the tail-cuff method. Vascular function, plasma nitric oxide (NO), glucose, lipid profiles, serum biochemical, and anti-oxidant parameters were also evaluated.

RESULTS

Rats fed with fructose showed higher blood pressure, serum cholesterol, and triglyceride levels, but decreased in the AELC or Losartan treatment group. Treatments with AELC prevented exaggerated plasma glucose and oxidative stress and restored the nitric oxide level in fructose-fed rats. Besides, it also reduced vascular proliferation and improved the relaxation response of acetylcholine in the aorta pre-contracted with phenylephrine.

CONCLUSION

In summary, the obtained results suggest that AELC can prevent and reverse the high blood pressure induced by fructose, probably by restoring nitric oxide level and by improving altered metabolic parameters.

Circulating bile acids as a link between the gut microbiota and cardiovascular health: impact of prebiotics, probiotics and polyphenol-rich foods

Beneficial effects of probiotic, prebiotic and polyphenol-rich interventions on fasting lipid profiles have been reported, with changes in the gut microbiota composition believed to play an important role in lipid regulation. Primary bile acids, which are involved in the digestion of fats and cholesterol metabolism, can be converted by the gut microbiota to secondary bile acids, some species of which are less well reabsorbed and consequently may be excreted in the stool. This can lead to increased hepatic bile acid neo-synthesis, resulting in a net loss of circulating low-density lipoprotein. Bile acids may therefore provide a link between the gut microbiota and cardiovascular health. This narrative review presents an overview of bile acid metabolism and the role of probiotics, prebiotics and polyphenol-rich foods in modulating circulating cardiovascular disease (CVD) risk markers and bile acids. Although findings from human studies are inconsistent, there is growing evidence for associations between these dietary components and improved lipid CVD risk markers, attributed to modulation of the gut microbiota and bile acid metabolism. These include increased bile acid neo-synthesis, due to bile sequestering action, bile salt metabolising activity and effects of short-chain fatty acids generated through bacterial fermentation of fibres. Animal studies have demonstrated effects on the FXR/FGF-15 axis and hepatic genes involved in bile acid synthesis (CYP7A1) and cholesterol synthesis (SREBP and HMGR). Further human studies are needed to determine the relationship between diet and bile acid metabolism and whether circulating bile acids can be utilised as a potential CVD risk biomarker.

IL-6/STAT3 and adipokine modulation using tocilizumab in rats with fructose-induced metabolic syndrome

Metabolic syndrome (MetS) is a low-grade inflammation state that results from an interplay between genetic and environmental factors. The incidence of MetS among individuals with insulin resistance, dyslipidemia, elevated blood pressure, and obesity, which constitute the syndrome, is 40% in the Middle East. The absence of an approved therapeutic agent for MetS is one reason to investigate tocilizumab (TCZ), which might be effective in the treatment of MetS. Results have implicated interleukin 6 (IL-6) in the development of MetS, identifying inflammation as a critical factor in its etiology and offering hope for new therapeutic approaches development. Here, we evaluate whether tocilizumab can be used for metabolic syndrome treatment. We assigned rats to three groups, 8 rats each: a negative-control group, provided with standard rodent chow and water; a fructose-fed group, provided with standard rodent chow and 10% fructose in drinking water for 22 weeks; and a treatment group, fed as per the metabolic syndrome group but treated with tocilizumab (5 mg/kg/week, intraperitoneal) for the final 5 weeks. Treatment with TCZ successfully ameliorated the damaging effects of fructose by stabilizing body weight gain and through the normalization of serum biochemical parameters and histopathological examination. Significant differences in adipokine levels were perceived, resulting in a significant decline in serum leptin and interleukin 6 (IL-6) levels concurrent with adiponectin normalization. Tocilizumab might be an effective agent for the treatment of metabolic syndrome. However, further investigations on human subjects are needed before the clinical application of tocilizumab for this indication.

Effects of TNF-α antagonist infliximab on fructose-induced metabolic syndrome in rats

Public health issues have been raised regarding fructose toxicity and its serious metabolic disorders. Deleterious effects of high fructose intake on insulin sensitivity, body weight, lipid homeostasis have been identified. The new millennium has witnessed the emergence of a modern epidemic, the metabolic syndrome (MS), in approximately 25% of the world's adult population. The current study aimed to investigate the effect of the TNF-α antagonist infliximab on fructose-induced MS in rats. Rats were administered fructose (10%) in drinking water for 12 weeks to induce the experimental MS model. infliximab (5 mg/kg) was injected once weekly intraperitoneally starting on the 13th week for 4 weeks. Increase in body weight, blood glucose level, serum triglycerides (TGs), adiponectin level and blood pressure were present in MS rats. They also prompted increases in serum of leptin, TNF-α, and malondialdehyde (MDA) levels. Treatment with infliximab did not affect body weight, hyperglycemia or hypertension, but decreased serum TGs and increased serum HDL-c levels. Infliximab also decreased adiponectin levels. Surprisingly, infliximab increased MDA above its value in the MS group. These results reflect the fact that infliximab affects the manifestations of MS in rats. Though infliximab reduced TGs, increased HDL-c levels, reversed adiponectin resistance occurred by fructose, the drug failed to combat MS-mediated hyperglycemia, hypertension, and elevated MDA above the insult.

Prolonged ursodeoxycholic acid administration reduces acute ischaemia-induced arrhythmias in adult rat hearts

Acute myocardial ischaemia and reperfusion (I-R) are major causes of ventricular arrhythmias in patients with a history of coronary artery disease. Ursodeoxycholic acid (UDCA) has previously been shown to be antiarrhythmic in fetal hearts. This study was performed to investigate if UDCA protects against ischaemia-induced and reperfusion-induced arrhythmias in the adult myocardium, and compares the effect of acute (perfusion only) versus prolonged (2 weeks pre-treatment plus perfusion) UDCA administration. Langendorff-perfused adult Sprague-Dawley rat hearts were subjected to acute regional ischaemia by ligation of the left anterior descending artery (10 min), followed by reperfusion (2 min), and arrhythmia incidence quantified. Prolonged UDCA administration reduced the incidence of acute ischaemia-induced arrhythmias (p = 0.028), with a reduction in number of ventricular ectopic beats during the ischaemic phase compared with acute treatment (10 ± 3 vs 58 ± 15, p = 0.036). No antiarrhythmic effect was observed in the acute UDCA administration group. Neither acute nor prolonged UDCA treatment altered the incidence of reperfusion arrhythmias. The antiarrhythmic effect of UDCA may be partially mediated by an increase in cardiac wavelength, due to the attenuation of conduction velocity slowing (p = 0.03), and the preservation of Connexin43 phosphorylation during acute ischaemia (p = 0.0027). The potential antiarrhythmic effects of prolonged UDCA administration merit further investigation.

TGR5 Signaling in Hepatic Metabolic Health

TGR5 is a G protein-coupled bile acid receptor that is increasingly recognized as a key regulator of glucose homeostasis. While the role of TGR5 signaling in immune cells, adipocytes and enteroendocrine L cells in metabolic regulation has been well described and extensively reviewed, the impact of TGR5-mediated effects on hepatic physiology and pathophysiology in metabolic regulation has received less attention. Recent studies suggest that TGR5 signaling contributes to improvements in hepatic insulin signaling and decreased hepatic inflammation, as well as metabolically beneficial improvements in bile acid profile. Additionally, TGR5 signaling has been associated with reduced hepatic steatosis and liver fibrosis, and improved liver function. Despite the beneficial effects of TGR5 signaling on metabolic health, TGR5-mediated gallstone formation and gallbladder filling complicate therapeutic targeting of TGR5 signaling. To this end, there is a growing need to identify cell type-specific effects of hepatic TGR5 signaling to begin to identify and target the downstream effectors of TGR5 signaling. Herein, we describe and integrate recent advances in our understanding of the impact of TGR5 signaling on liver physiology and how its effects on the liver integrate more broadly with whole body glucose regulation.

Prolonged overnutrition with fructose or fat induces metabolic derangements in rats by disrupting the crosstalk between the hypothalamus and periphery: Possible amelioration with fenofibrate

Metabolic Syndrome (MetS) increases the risk of developing type 2 diabetes mellitus and cardiovascular complications. The crosstalk between the hypothalamus and periphery is vital for regulating food intake and energy homeostasis. However, it is impaired during MetS. The present study aimed to compare the distinct central and peripheral metabolic derangements induced by a high-fructose drink or high-fat diet, as well as the possible intervention by fenofibrate. Rats were divided into five groups: standard chow diet (SCD) group, high-fructose group (FR), high-fat group (HF), FR plus fenofibrate group (FR-F), and HF plus fenofibrate group (HF-F). FR and HF groups showed hyperglycemia, hyperinsulinemia, hypertriglyceridemia, hyperleptinemia, steatosis, and adipocyte hypertrophy. This was associated with elevated circulating levels of proinflammatory cytokines and free fatty acids (FFAs). The latter mediators are involved in the hypothalamic inflammation and dysregulation of signaling cascades that control food intake and glucose homeostasis. The effects were more pronounced in the HF group than FR group, which were matched with the observed higher levels of plasma FFAs and cytokines. Fenofibrate administration improved not only the peripheral metabolic disturbances, but also the central disturbances associated with insulin resistance induced by FR or HF diet. This study sheds light on the pivotal role of the hypothalamus in diet-induced MetS. Furthermore, the study suggests the utmost importance of developing a standardized model of metabolic syndrome in place of the great diversity between available models, which can induce different effects and negatively impact the validity of prospective studies.

Fructose Feeding and Hyperuricemia: a Systematic Review and Meta-Analysis

High fructose feeding has been suggested to involve in several features of metabolic syndrome including hyperuricemia (HP). We designed and implemented a study to determine the effect size of fructose intake and the relative risk of HP based on the type of fructose feeding (diet or solution), duration of treatment (2–6, 7–10, and > 10 weeks), and animal race. The required information was accepted from international databases, including PubMed/MEDLINE, Science Direct, Scopus, and etc., from 2009 until 2019 on the basis of predetermined eligibility criteria. The data selection and extraction and quality assessment were performed independently by two researchers. Results were pooled as random effects weighting and reported as standardized mean differences with 95% confidence intervals. Thirty-five studies including 244 rats with fructose consumption were included in the final analysis. The heterogeneity rate of parameters was high (I2 = 81.3%, p < 0.001) and estimated based on; 1) type of fructose feeding (diet; I2 = 79.3%, solution 10%; I2 = 83.4%, solution 20%; I2 = 81.3%), 2) duration of treatment (2–6 weeks; I2 = 86.8%, 7–10 weeks; I2 = 76.3%, and > 10 weeks; I2 = 82.8%), 3) the animal race (Wistar; I2 = 78.6%, Sprague-Dawley; I2 = 83.9%). Overall, the pooled estimate for the all parameters was significant (p < 0.001). The results of this study indicated that a significant relationship between HP and fructose intake regardless of the treatment duration, animal race, fructose concentration and route of consumption.

Nicotinamide reduces inflammation and oxidative stress via the cholinergic system in fructose-induced metabolic syndrome in rats

AIMS

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) have been associated with risk factors for metabolic syndrome (MetS). Our objective was to evaluate the effect of nicotinamide (NAM) on the activities, expression and protein content of cholinesterases in a MetS model.

MAIN METHODS

MetS was induced in male rats administrating 40% fructose to the drinking water for 16 weeks. Additionally, from 5th week onward, the carbohydrate solution was replaced by NAM, at several concentrations for 5 h each morning for the next 12 weeks. In the 15th week, the glucose tolerance test was conducted, and blood pressure was measured. After the treatment period had concluded, the biochemical profile; oxidant stress; proinflammatory markers; and the activity, quantity and expression of cholinesterases were evaluated, and molecular docking analysis was performed.

KEY FINDINGS

The MetS group showed anthropometric, hemodynamic and biochemical alterations and increased cholinesterase activity, inflammation and stress markers. In the liver, cholinesterase activity and mRNA, free fatty acid, tumor necrosis factor-alpha (TNF-α), and thiobarbituric acid-reactive substance (TBARS) levels were increased, while reduced glutathione (GSH) levels were decreased. NAM partially or totally decreased risk factors for MetS, markers of stress and inflammation, and the activity (serum and liver) and expression (liver) of cholinesterases. Molecular docking analysis showed that NAM has a greater affinity for cholinesterases than acetylcholine (ACh), suggesting NAM as an inhibitor of cholinesterases.

SIGNIFICANCE

Supplementation with 40% fructose induced MetS, which increased the activity and expression of cholinesterases, oxidative stress and the inflammation. NAM attenuated these MetS-induced alterations and changes in cholinesterases.

The concurrent exposure to aluminium and fructose induces liver injury in rats: Protection by monoammonium glycyrrhizinate

Aluminium is a ubiquitous element that occurs naturally in the soil making human exposure to it unavoidable. It is implicated in the aetiology of different neurodegenerative diseases and can induce liver injury. In addition, insulin resistance (IR) plays an essential role in the pathogenesis and the progression of liver disorders. The increased consumption of fructose contained in soft drinks and western pattern diet results in IR that along with the wide distribution of aluminium make the concurrent exposure conceivable and increase the risk of liver injury. Therefore, the present study explores the hepatotoxic effects of aluminium and fructose administered concurrently and evaluates the possible protection by monoammonium glycyrrhizinate (MAG). Liver injury was induced by the administration of aluminium chloride (34 mg/kg/d) plus 10% (w/v) fructose in drinking water. Male rats were treated with either MAG (40 mg/kg/d) or silymarin (SIL, 100 mg/kg/d). The concurrent administration of aluminium and fructose (FRUAL) induced liver injury manifested as a significant elevation of serum liver enzymes activities, bilirubin level, and prothrombin time, as well as reduction of albumin level. On the other hand, the administration of MAG improved the FRUAL-induced aberrations of liver function tests and hepatic cytoarchitecture. We assume that the MAG-induced suppression of oxidative stress, toll-like receptor 4 pathway activation, inflammation, and apoptosis might play a crucial role in the hepatoprotective effect of MAG in this model. Intriguingly, the hepatoprotective effect MAG against FRUAL-induced liver injury surpasses that of the gold standard SIL, suggesting MAG as a better alternative to SIL.

Effect of imidazoline-1 receptor agonists on renal dysfunction in rats associated with chronic, sequential fructose and ethanol administration

Insulin resistance and chronic alcoholism are risk factors for renal dysfunction. This study investigated the therapeutic effects of two imidazoline-1 receptor (I1R) agonists on renal dysfunction in rats after chronic, sequential fructose and ethanol administration. Daily drinking water was supplemented with fructose (10%, w/v) for 12 weeks and then with ethanol (20%, v/v) for another 8 weeks. Rats were treated with rilmenidine and clonidine in the last two weeks of the study. Blood glucose and serum insulin (sIns) levels, lipid profiles, kidney function and renal histopathology were evaluated at the end of the experiment. Additionally, renal gene expression of nischarin, phosphatidylcholine-specific phospholipase C (PC-PLC) and prostaglandin E2 (PGE2) were measured. Renal levels of superoxide dismutase (SOD), malondialdehyde (MDA), myeloperoxidase (MPO), inducible nitric oxide synthase (iNOS) and total NO (tNO) were detected, and we determined the relative renal gene expression levels of alpha smooth muscle actin (α-SMA), hydroxyproline, interleukin 10 (IL-10), tumour necrosis factor alpha (TNF-α) and caspase-3. The results showed significant deterioration of blood glucose, sIns, lipid profiles, kidney function and renal histopathology in fructose/ethanol-fed rats. Additionally, markers of inflammation, fibrosis, apoptosis and oxidative stress were upregulated. The administration of rilmenidine or clonidine significantly improved blood glucose and sIns levels and reduced renal dysfunction. Our work showed that chronic, sequential fructose and ethanol administration induced fasting hyperglycaemia and renal impairment, and these effects were ameliorated by I1R agonists.

The Function of PPARγ/AMPK/SIRT-1 Pathway in Inflammatory Response of Human Articular Chondrocytes Stimulated by Advanced Glycation End Products

Accumulation of advanced glycation end products (AGEs) in the articular cartilage is a major risk factor for osteoarthritis (OA). To determine the mechanistic basis of AGE action in OA, we treated human articular chondrocytes with AGEs, and found that they not only up-regulated the pro-inflammatory cytokines interleukin (IL)-1β and tumor necrosis factor (TNF)-α, but also inhibited AMP-activated protein kinase (AMPK) phosphorylation and decreased sirtuin 1 (SIRT-1) levels in a concentration- and time-dependent manner. Pioglitazone, a peroxisome proliferator-activated receptor-γ (PPARγ) agonist restored the inhibited AMPK and SIRT-1 by AGEs. Pre-treatment of the cells with the agonists or antagonists of AMPK and SIRT-1 respectively abolished and augmented the inflammatory state induced by AGEs. Furthermore, AMPK agonist also restored the levels of SIRT-1 in the AGE-stimulated chondrocytes. Our findings indicate AGEs induce an inflammatory response in human articular chondrocytes via the PPARγ/AMPK/SIRT-1 pathway, which is therefore a potential target in OA therapy.

Bile-ology: from bench to bedside

Bile acids (BAs) are originally known as detergents essential for the digestion and absorption of lipids. In recent years, extensive research has unveiled new functions of BAs as gut hormones that modulate physiological and pathological processes, including glucose and lipid metabolism, energy expenditure, inflammation, tumorigenesis, cardiovascular disease, and even the central nervous system in addition to cholesterol homeostasis, enterohepatic protection and liver regeneration. BAs are closely linked with gut microbiota which might explain some of their crucial roles in organs. The signaling actions of BAs can also be mediated through specific nuclear receptors and membrane-bound G protein-coupled receptors. Several pharmacological agents or bariatric surgeries have demonstrated efficacious therapeutic effects on metabolic diseases through targeting BA signaling. In this mini-review, we summarize recent advances in bile-ology, focusing on its translational studies.

Gut microbiota and health: connecting actors across the metabolic system

Overweight-related metabolic diseases are an important threat to health in the Western world. Dietary habits are one of the main causative factors for metabolic syndrome, CVD and type 2 diabetes. The human gut microbiota is emerging as an important player in the interaction between diet and metabolic health. Gut microbial communities contribute to human metabolism through fermentation of dietary fibre and the result of intestinal saccharolytic fermentation is production of SCFA. Acetate, propionate and butyrate positively influence satiety, endocrine system, glucose homeostasis, adipogenesis, lipid oxidation, thermoregulation, hepatic gluconeogenesis, endothelial function and gut barrier integrity, and these mechanisms have all been linked to protection from type 2 diabetes, hypertension and cardiovascular health. The gut microbiota is also involved in bile acid metabolism and regulating their cell signalling potential, which has also been shown to modify pathways involved in metabolic health. Similarly, the gut microbiota renders recalcitrant plant polyphenols into biologically active small phenolic compounds which then act systemically to reduce metabolic disease risk. This review summarises how dietary patterns, specific foods and a healthy lifestyle may modulate metabolic health through the gut microbiota and their molecular cross-talk with the host.

Overview of Bile Acids Signaling and Perspective on the Signal of Ursodeoxycholic Acid, the Most Hydrophilic Bile Acid, in the Heart

Bile acids (BA) are classically known as an important agent in lipid absorption and cholesterol metabolism. Nowadays, their role in glucose regulation and energy homeostasis are widely reported. BAs are involved in various cellular signaling pathways, such as protein kinase cascades, cyclic AMP (cAMP) synthesis, and calcium mobilization. They are ligands for several nuclear hormone receptors, including farnesoid X-receptor (FXR). Recently, BAs have been shown to bind to muscarinic receptor and Takeda G-protein-coupled receptor 5 (TGR5), both G-protein-coupled receptor (GPCR), independent of the nuclear hormone receptors. Moreover, BA signals have also been elucidated in other nonclassical BA pathways, such as sphingosine-1-posphate and BK (large conductance calcium- and voltage activated potassium) channels. Hydrophobic BAs have been proven to affect heart rate and its contraction. Elevated BAs are associated with arrhythmias in adults and fetal heart, and altered ratios of primary and secondary bile acid are reported in chronic heart failure patients. Meanwhile, in patients with liver cirrhosis, cardiac dysfunction has been strongly linked to the increase in serum bile acid concentrations. In contrast, the most hydrophilic BA, known as ursodeoxycholic acid (UDCA), has been found to be beneficial in improving peripheral blood flow in chronic heart failure patients and in protecting the heart against reperfusion injury. This review provides an overview of BA signaling, with the main emphasis on past and present perspectives on UDCA signals in the heart.

Rethinking Bile Acid Metabolism and Signaling for Type 2 Diabetes Treatment

PURPOSE OF REVIEW

Herein, we review the role of FXR and TGR5 in the regulation of hepatic bile acid metabolism, with a focus on how our understanding of bile acid metabolic regulation by these receptors has evolved in recent years and how this improved understanding may facilitate targeting bile acids for type 2 diabetes treatment.

RECENT FINDINGS

Bile acid profile is a key regulator of metabolic homeostasis. Inhibition of expression of the enzyme that is required for cholic acid synthesis and thus determines bile acid profile, Cyp8b1, may be an effective target for type 2 diabetes treatment. FXR and, more recently, TGR5 have been shown to regulate bile acid metabolism and Cyp8b1 expression and, therefore, may provide a mechanism with which to target bile acid profile for type 2 diabetes treatment. Inhibition of Cyp8b1 expression is a promising therapeutic modality for type 2 diabetes; however, further work is needed to fully understand the pathways regulating Cyp8b1 expression.

Argan Oil as an Effective Nutri-Therapeutic Agent in Metabolic Syndrome: A Preclinical Study

The present study aims at examining the effects of argan oil on the three main cardiovascular risk factors associated with metabolic syndrome (hypertension, insulin resistance and obesity) and on one of its main complications, neuropathic pain. Male Sprague-Dawley rats had free access to a drinking solution containing 10% d-glucose or tap water for 12 weeks. The effect of argan oil was compared to that of corn oil given daily by gavage during 12 weeks in glucose-fed rats. Glucose-fed rats showed increases in systolic blood pressure, epididymal fat, plasma levels of triglycerides, leptin, glucose and insulin, insulin resistance, tactile and cold allodynia in association with a rise in superoxide anion production and NADPH oxidase activity in the thoracic aorta, epididymal fat and gastrocnemius muscle. Glucose-fed rats also showed rises in B₁ receptor protein expression in aorta and gastrocnemius muscle. Argan oil prevented or significantly reduced all those anomalies with an induction in plasma adiponectin levels. In contrast, the same treatment with corn oil had a positive impact only on triglycerides, leptin, adiponectin and insulin resistance. These data are the first to suggest that argan oil is an effective nutri-therapeutic agent to prevent the cardiovascular risk factors and complications associated with metabolic syndrome.

Impact of Fish Oil Supplementation and Interruption of Fructose Ingestion on Glucose and Lipid Homeostasis of Rats Drinking Different Concentrations of Fructose

Background. Continuous fructose consumption may cause elevation of circulating triacylglycerol. However, how much of this alteration is reverted after the removal of fructose intake is not known. We explored this question and compared the efficacy of this approach with fish oil supplementation. Methods. Male Wistar rats were divided into the following groups: control (C), fructose (F) (water intake with 10% or 30% fructose for 9 weeks), fish oil (FO), and fructose/fish oil (FFO). Fish oil was supplemented only for the last 33 days of fructose ingestion. Half of the F group remained for additional 8 weeks without fructose ingestion (FR). Results. Fructose ingestion reduced food intake to compensate for the increased energy obtained through water ingestion, independent of fructose concentration. Fish oil supplementation exerted no impact on these parameters, but the removal of fructose from water recovered both ingestion behaviors. Plasma triacylglycerol augmented significantly during the second and third weeks (both fructose groups). Fish oil supplementation did not attenuate the elevation in triacylglycerol caused by fructose intake, but the interruption of sugar consumption normalized this parameter. Conclusion. Elevation in triacylglyceridemia may be recovered by removing fructose from diet, suggesting that it is never too late to repair improper dietary habits.

Ursodeoxycholic Acid Suppresses Lipogenesis in Mouse Liver: Possible Role of the Decrease in β-Muricholic Acid, a Farnesoid X Receptor Antagonist

The farnesoid X receptor (FXR) is a major nuclear receptor of bile acids; its activation suppresses sterol regulatory element-binding protein 1c (SREBP1c)-mediated lipogenesis and decreases the lipid contents in the liver. There are many reports showing that the administration of ursodeoxycholic acid (UDCA) suppresses lipogenesis and reduces the lipid contents in the liver of experimental animals. Since UDCA is not recognized as an FXR agonist, these effects of UDCA cannot be readily explained by its direct activation of FXR. We observed that the dietary administration of UDCA in mice decreased the expression levels of SREBP1c and its target lipogenic genes. Alpha- and β-muricholic acids (MCA) and cholic acid (CA) were the major bile acids in the mouse liver but their contents decreased upon UDCA administration. The hepatic contents of chenodeoxycholic acid and deoxycholic acid (DCA) were relatively low but were not changed by UDCA. UDCA did not show FXR agonistic or antagonistic potency in in vitro FXR transactivation assay. Taking these together, we deduced that the above-mentioned change in hepatic bile acid composition induced upon UDCA administration might cause the relative increase in the FXR activity in the liver, mainly by the reduction in the content of β-MCA, a farnesoid X receptor antagonist, which suggests a mechanism by which UDCA suppresses lipogenesis and decreases the lipid contents in the mouse liver.

Formation of Fructose-Mediated Advanced Glycation End Products and Their Roles in Metabolic and Inflammatory Diseases

Fructose is associated with the biochemical alterations that promote the development of metabolic syndrome (MetS), nonalcoholic fatty liver disease, and type 2 diabetes. Its consumption has increased in parallel with MetS. It is metabolized by the liver, where it stimulates de novo lipogenesis. The triglycerides synthesized lead to hepatic insulin resistance and dyslipidemia. Fructose-derived advanced glycation end products (AGEs) may be involved via the Maillard reaction. Fructose has not been a main focus of glycation research because of the difficulty in measuring its adducts, and, more importantly, because although it is 10 times more reactive than glucose, its plasma concentration is only 1% of that of glucose. In this focused review, I summarize exogenous and endogenous fructose metabolism, fructose glycation, and in vitro, animal, and human data. Fructose is elevated in several tissues of diabetic patients where the polyol pathway is active, reaching the same order of magnitude as glucose. It is plausible that the high reactivity of fructose, directly or via its metabolites, may contribute to the formation of intracellular AGEs and to vascular complications. The evidence, however, is still unconvincing. Two areas that have been overlooked so far and should be actively explored include the following: 1) enteral formation of fructose AGEs, generating an inflammatory response to the receptor for AGEs (which may explain the strong association between fructose consumption and asthma, chronic bronchitis, and arthritis); and 2) inactivation of hepatic AMP-activated protein kinase by a fructose-mediated increase in methylglyoxal flux (perpetuating lipogenesis, fatty liver, and insulin resistance). If proven correct, these mechanisms would put the fructose-mediated Maillard reaction in the limelight again as a contributing factor in chronic inflammatory diseases and MetS.

Bariatric surgery in managing diabetes mellitus

PURPOSE OF REVIEW

Obesity is a worldwide epidemic, having profound effects on Western populations. Bariatric surgery has long been employed to treat obesity and its related comorbidities. Over time, researchers have amassed significant data to support bariatric surgery in the pursuit of treating diabetes mellitus. This review serves to introduce the most recent findings and their relation to the various bariatric surgical options as bariatric surgery will continue to cement itself in the treatment paradigm of diabetes mellitus.

RECENT FINDINGS

Numerous studies performed in the past 10 years have demonstrated the improvement or cessation of diabetes with bariatric surgical intervention. In comparing the vertical sleeve gastrectomy and Roux-en-Y gastric bypass, data demonstrate a more beneficial response of diabetes to the Roux-en-Y gastric bypass, and an even further exaggerated response with the biliopancreatic diversion/duodenal switch. The benefit has long been established, but what causes the improvement in diabetes mellitus after bariatric surgery? Recent data suggest a decrease in circulating bile salts as well as changes to inflammatory markers and circulating cytokines. Furthermore, tailoring of existing surgical procedures has led to the development of the SIPS procedure, and its benefit is demonstrated in bypassing a large portion of intestine while eliminating an enteroenterostomy, helping to reduce short gut syndrome and resultant diarrhea.

SUMMARY

The surgical climate within the bariatric field is changing and will continue to do so in the future. As the understanding of the causes or mechanisms in which bariatric surgery improves metabolic disorders becomes more evident, the process of individualizing care for specific patients will become more prevalent.

Animal models of metabolic syndrome: a review

Metabolic syndrome (MetS) consists of several medical conditions that collectively predict the risk for cardiovascular disease better than the sum of individual conditions. The risk of developing MetS in human depends on synergy of both genetic and environmental factors. Being a multifactorial condition with alarming rate of prevalence nowadays, establishment of appropriate experimental animal models mimicking the disease state in humans is crucial in order to solve the difficulties in evaluating the pathophysiology of MetS in human. This review aims to summarize the underlying mechanisms involved in the pathophysiology of dietary, genetic, and pharmacological models of MetS. Furthermore, we will discuss the usefulness, suitability, pros and cons of these animal models. Even though numerous animal models of MetS have been established, further investigations on the invention of new animal model and clarification of plausible mechanisms are still necessary to confer a better understanding to researchers on the selection of animal models for their studies.

Fructose Beverage Consumption Induces a Metabolic Syndrome Phenotype in the Rat: A Systematic Review and Meta-Analysis

A high intake of refined carbohydrates, particularly the monosaccharide fructose, has been attributed to the growing epidemics of obesity and type-2 diabetes. Animal studies have helped elucidate the metabolic effects of dietary fructose, however, variations in study design make it difficult to draw conclusions. The aim of this study was to review the effects of fructose beverage consumption on body weight, systolic blood pressure and blood glucose, insulin and triglyceride concentrations in validated rat models. We searched Ovid Embase Classic + EmbaseMedline and Ovid Medline databases and included studies that used adolescent/adult male rats, with fructose beverage consumption for >3 weeks. Data from 26 studies were pooled by an inverse variance weighting method using random effects models, expressed as standardized mean differences (SMD) with 95% confidence intervals (CI). Overall, 10%–21% w/v fructose beverage consumption was associated with increased rodent body weight (SMD, 0.62 (95% CI: 0.18, 1.06)), systolic blood pressure (SMD, 2.94 (95% CI: 2.10, 3.77)) and blood glucose (SMD, 0.77 (95% CI: 0.36, 1.19)), insulin (SMD, 2.32 (95% CI: 1.57, 3.07)) and triglyceride (SMD, 1.87 (95% CI: 1.39, 2.34)) concentrations. Therefore, the consumption of a low concentration fructose beverage is sufficient to cause early signs of the metabolic syndrome in adult rats.

α-Amyrin attenuates high fructose diet-induced metabolic syndrome in rats

This study investigated the effect of α-amyrin (a pentacyclic triterpene) on high-fructose diet (HFD)-induced metabolic syndrome in rats. Male Wistar rats were randomly distributed into different groups. The control group was fed normal rat chow diet. The HFD group was fed HFD (60%; w/w) for 42 days. Pioglitazone (10 mg/kg, orally, once daily) was used as a standard drug. α-Amyrin was administered in 3 doses (50, 100, and 200 mg/kg, orally, once daily along with HFD). Plasma glucose, total cholesterol, triglycerides, and high-density lipoprotein cholesterol (HDL-C) were estimated. Changes in blood pressure, oral glucose tolerance, and insulin tolerance were measured. Hepatic oxidative stress as well as messenger RNA (mRNA) and protein levels of peroxisome proliferator-activated receptor alpha (PPAR-α) were analyzed. A significant increase in systolic blood pressure, plasma glucose, total cholesterol, and plasma triglycerides and a significant decrease in HDL-C were observed in HFD rats as compared with control rats. Glucose tolerance and insulin tolerance were also significantly impaired with HFD. α-Amyrin prevented these changes in a dose-dependent manner. Hepatic oxidative stress as well as micro- and macrovesicular fatty changes in hepatocytes caused by HFD were also attenuated by α-amyrin. α-Amyrin preserved the hepatic mRNA and protein levels of PPAR-α, which was reduced in HFD group. This study thus demonstrates that α-amyrin attenuates HFD-induced metabolic syndrome in rats.

Protective effect of ursodeoxycholic acid, resveratrol, and N-acetylcysteine on nonalcoholic fatty liver disease in rats

CONTEXT

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. Resveratrol (RSV) and N-acetylcysteine (NAC) are safe representatives of natural and synthetic antioxidants, respectively.

OBJECTIVE

The objective of this study was to evaluate protective effects of RSV and NAC, compared with ursodeoxycholic acid (UDCA), on experimental NAFLD.

MATERIALS AND METHODS

NAFLD was induced by feeding rats a methionine choline-deficient diet (MCDD) for four cycles, each of 4 d of MCDD feeding and 3 d of fasting. Animals were divided into normal control, steatosis control, and five treatment groups, receiving UDCA (25 mg/kg/d), RSV (10 mg/kg/d), NAC (20 mg/kg/d), UDCA + RSV, and UDCA + NAC orally for 28 d. Liver integrity markers (liver index and serum transaminases), serum tumor necrosis factor-α (TNF-α), glucose, albumin, renal functions (urea, creatinine), lipid profile (total cholesterol; TC, triglycerides, high density lipoproteins, low density lipoproteins; LDL-C, very low density lipoproteins, leptin), and oxidative stress markers (hepatic malondialdehyde; MDA, glutathione; GSH, glutathione-S-transferase; GST) were measured using automatic analyzer, colorimetric kits, and ELISA kits, supported by a liver histopathological study.

RESULTS

RSV and NAC administration significantly improved liver index (RSV only), alanine transaminase (52, 52%), TNF-α (70, 70%), glucose (69, 80%), albumin (122, 114%), MDA (55, 63%), GSH (160, 152%), GST (84, 84%), TC (86, 86%), LDL-C (83, 81%), and leptin (59, 70%) levels compared with steatosis control values. A combination of RSV or NAC with UDCA seems to ameliorate their effects.

DISCUSSION AND CONCLUSION

RSV and NAC are effective on NAFLD through antioxidant, anti-inflammatory, and lipid-lowering potentials, where as RSV seems better than UDCA or NAC.

Protective effect of curcumin in fructose-induced metabolic syndrome and in streptozotocin-induced diabetes in rats

OBJECTIVE

The aim of this study was to investigate the effect of pre-treatment with curcumin on metabolic changes induced by two different pathophysiological mechanisms in rats (fructose diet and streptozotocin (STZ)-induced diabetes mellitus).

MATERIALS AND METHODS

Five groups with 10 rats per group were investigated: control group (healthy rats), fructose diet groups without any pre-treatment (FD), fructose diet groups with curcumin pre-treatment (FDC), STZ-induced diabetes mellitus without any pre-treatment (SID) and STZ-induced diabetes mellitus with curcumin pre-treatment (SIDC). Systolic blood pressure, and several metabolic and oxidative stress parameters were assessed.

RESULTS

Systolic blood pressure significantly increased in all groups compared with control group (P<0.001), with significantly lower values on groups with curcumin pre-treatment compared with the group without any pre-treatment and same inducement (FDS vs. FD P<0.0001, SIDC vs. SID P<0.0001). High-density lipoprotein (HDL)-cholesterol was significantly lower in all groups compared with control group (P<0.05) while triglycerides (P<0.05), aspartate aminotransferase (AST, P<0.0001) and alanine aminotransferase (ALT, P<0.0001) were significantly higher. Within the group with same induction, curcumin pre-treatment significantly improved metabolic (total cholesterol, glycaemia, triglycerides, AST, ALT; P<0.05) and oxidative stress parameters (total oxidative status (NOx), Thiol, and malondialdehyde (MDA), P<0.02) compared to untreated groups.

CONCLUSION

The pre-treatment with curcumin in our experimental models significantly improved metabolic (total cholesterol, triglycerides, AST and ALT) as well as oxidative stress parameters (MDA, NOx, and Thiol) in both fructose diet and in STZ-induced diabetes in rats. These properties of curcumin may serve to improve the metabolic and oxidative stress conditions in patients with these pathological features.

Histopathologic and metabolic effect of ursodeoxycholic acid treatment on PCOS rat model

The aim of this study was to determine the effect of ursodeoxycholic acid (UDCA) treatment on a polycystic ovary syndrome (PCOS) rat model. Thirty-two female Wistar-Albino rats were randomly divided into four groups as follows - group 1: sham group (n: 8), group 2: letrozole-induced PCOS group (n: 8), group 3: letrozole-induced PCOS plus metformin-treated (500 mg/kg) group (n: 8) and group 4: letrozole-induced PCOS plus UDCA (150 mg/kg)-treated group (n: 8). Histopathologic examination of the ovaries, circulating estrone (E1), estradiol (E2), testosterone, androstenedione, glucose, insulin and lipid profiles were evaluated. Histopathologic examination results revealed that groups 3 and 4 had significantly lower cystic and atretic follicles compared to group 2. Besides, group 4 had significantly higher antral follicles than group 2 (8.5 ± 2.9 versus 5.4 ± 1.1; p: 0.001). Furthermore, total testosterone (4.9 ± 2.8 versus 8.8 ± 2.9; p= 0.004) and insulin levels were significantly lower in group 4 compared to group 2 (1.7 ± 0.08 versus 2.1 ± 0.5; p = 0.02). However, lipid parameters, E1, E2, glucose and HOMA-IR were comparable between the groups. Our study results demonstrated that UDCA therapy improves ovarian morphology and decreases total testosterone and insulin levels.

Consequences of bile salt biotransformations by intestinal bacteria

Emerging evidence strongly suggest that the human "microbiome" plays an important role in both health and disease. Bile acids function both as detergents molecules promoting nutrient absorption in the intestines and as hormones regulating nutrient metabolism. Bile acids regulate metabolism via activation of specific nuclear receptors (NR) and G-protein coupled receptors (GPCRs). The circulating bile acid pool composition consists of primary bile acids produced from cholesterol in the liver, and secondary bile acids formed by specific gut bacteria. The various biotransformation of bile acids carried out by gut bacteria appear to regulate the structure of the gut microbiome and host physiology. Increased levels of secondary bile acids are associated with specific diseases of the GI system. Elucidating methods to control the gut microbiome and bile acid pool composition in humans may lead to a reduction in some of the major diseases of the liver, gall bladder and colon.

Functional foods as potential therapeutic options for metabolic syndrome

Obesity as part of metabolic syndrome is a major lifestyle disorder throughout the world. Current drug treatments for obesity produce small and usually unsustainable decreases in body weight with the risk of major adverse effects. Surgery has been the only treatment producing successful long-term weight loss. As a different but complementary approach, lifestyle modification including the use of functional foods could produce a reliable decrease in obesity with decreased comorbidities. Functional foods may include fruits such as berries, vegetables, fibre-enriched grains and beverages such as tea and coffee. Although health improvements continue to be reported for these functional foods in rodent studies, further evidence showing the translation of these results into humans is required. Thus, the concept that these fruits and vegetables will act as functional foods in humans to reduce obesity and thereby improve health remains intuitive and possible rather than proven.

Geraniol, alone and in combination with pioglitazone, ameliorates fructose-induced metabolic syndrome in rats via the modulation of both inflammatory and oxidative stress status

Geraniol (GO) potent antitumor and chemopreventive effects are attributed to its antioxidant and anti-inflammatory properties. In the current study, the potential efficacy of GO (250 mg/kg) in ameliorating metabolic syndrome (MetS) induced by fructose in drinking water was elucidated. Moreover, the effect of pioglitazone (5 and 10 mg/kg; PIO) and the possible interaction of the co-treatment of GO with PIO5 were studied in the MetS model. After 4 weeks of treatment, GO and/or PIO reduced the fasting blood glucose and the glycemic excursion in the intraperitoneal glucose tolerance test. GO and PIO5/10 restrained visceral adiposity and partly the body weight gain. The decreased level of peroxisome proliferator activated receptor (PPAR)-γ transcriptional activity in the visceral adipose tissue of MetS rats was increased by single treatment regimens. Though GO did not affect MetS-induced hyperinsulinemia, PIO5/10 lowered it. Additionally, GO and PIO5/10 suppressed glycated hemoglobin and the receptor for advanced glycated end products (RAGE). These single regimens also ameliorated hyperuricemia, the disrupted lipid profile, and the elevated systolic blood pressure evoked by MetS. The rise in serum transaminases, interleukin-1β, and tumor necrosis factor-α, as well as hepatic lipid peroxides and nitric oxide (NO) was lowered by the single treatments to different extents. Moreover, hepatic non-protein thiols, as well as serum NO and adiponectin were enhanced by single regimens. Similar effects were reached by the combination of GO with PIO5; however, a potentiative interaction was noted on fasting serum insulin level, while synergistic effects were reflected as improved insulin sensitivity, as well as reduced RAGE and triglycerides. Therefore, GO via the transcriptional activation of PPAR-γ reduces inflammation and free radical injury produced by MetS. Thereby, these effects provide novel mechanistic insights on GO management of MetS associated critical risk factors. Moreover, the co-administration of GO to PIO5 exalted the antidiabetic drug anti-MetS efficacy.