Protective effect of ursodeoxycholic acid on liver mitochondrial function in rats with alloxan-induced diabetes: link with oxidative stress

Ursodeoxycholic and chenodeoxycholic bile acids attenuate systemic and liver inflammation induced by lipopolysaccharide in rats

Bacterial lipopolysaccharide (LPS) induces general inflammation, by activating pathways involving cytokine production, blood coagulation, complement system activation, and acute phase protein release. The key cellular players are leukocytes and endothelial cells, that lead to tissue injury and organ failure. The aim of this study was to explore the anti-inflammatory, antioxidant, and cytoprotective properties of two bile acids, ursodeoxycholic acid (UDCA) and chenodeoxycholic acid (CDCA) in LPS-induced endotoxemia in rats. The experiment involved six distinct groups of Wistar rats, each subjected to different pretreatment conditions: control and LPS groups were pretreated with propylene glycol, as a bile acid solvent, while the other groups were pretreated with UDCA or CDCA for 10 days followed by an LPS injection on day 10. The results showed that both UDCA and CDCA reduced the production of pro-inflammatory cytokines: TNF-α, GM-CSF, IL-2, IFNγ, IL-6, and IL-1β and expression of nuclear factor-κB (NF-κB) induced by LPS. In addition, pretreatment with these bile acids showed a positive impact on lipid profiles, a decrease in ICAM levels, an increase in antioxidant activity (SOD, |CAT, GSH), and a decrease in prooxidant markers (H2O2 and O2-). Furthermore, both bile acids alleviated LPS-induced liver injury. While UDCA and CDCA pretreatment attenuated homocysteine levels in LPS-treated rats, only UDCA pretreatment showed reductions in other serum biochemical markers, including creatine kinase, lactate dehydrogenase, and high-sensitivity troponin I. It can be concluded that both, UDCA and CDCA, although exerted slightly different effects, can prevent the inflammatory responses induced by LPS, improve oxidative stress status, and attenuate LPS-induced liver injury.

Therapeutic benefit of ursodeoxycholic acid in tamoxifen-induced hepatotoxicity in Wistar rats

Background. The clinical use of tamoxifen (TAM) may cause hepatotoxicity. Ursodeoxycholic acid (UDCA) has promising liver protective activity. This study assessed the protective effect of UDCA on TAM-induced hepatotoxicity in rats.Material and methods. Thirty five adult female Wistar rats were grouped into 7 of n=5/group. The rats were treated for 10 days as follows: Group 1: Water (10 mL/kg/day; placebo control) per oral [p.o], group 2: Ethanol 1% (1mL/kg/day; vehicle control) intraperitoneally (i.p), group 3: UDCA (40 mg/kg/day/p.o) and group 4: TAM (45 mg/kg/day) i.p. Groups 5-7 were pretreated with UDCA (10, 20 and 40 mg/kg), before daily treatment with TAM (45 mg/kg/day) i.p, respectively. On day 11, blood samples were collected and assessed for serum liver biomarkers. Liver samples were evaluated for oxidative stress markers and histology.Results. Significantly (p<0.05) decreased body weight and significantly (p<0.01) increased liver weight occurred in TAM- treated rats when compared to placebo control. TAM significantly (p<0.001) increased serum alkaline phosphatase, lactate dehydrogenase, gamma-glutamyl transferase, aminotransferases, bilirubin, high density lipoprotein cholesterol levels and liver malondialdehyde levels when compared to control. TAM significantly (p<0.001) decreased liver glutathione, catalase, glutathione peroxidase, superoxide dismutase, serum total protein, albumin total cholesterol, low density lipoprotein cholesterol and triglyceride levels when compared to control. Steatosis and necrotic changes occurred in TAM-treated rats. UDCA pretreatment significantly prevents TAM-induced changes in serum biochemical markers, and oxidative stress indices in a dose-related fashion when compared to TAM. UDCA prevents TAM-induced changes in liver histology.Conclusion. UDCA may be clinically effective for TAM associated hepatotoxicity.

Bile acids-gut microbiota crosstalk contributes to the improvement of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) occurs that cannot effectively use the insulin. Insulin Resistance (IR) is a significant characteristic of T2DM which is also an essential treatment target in blood glucose regulation to prevent T2DM and its complications. Bile acids (BAs) are one group of bioactive metabolites synthesized from cholesterol in liver. BAs play an important role in mutualistic symbiosis between host and gut microbiota. It is shown that T2DM is associated with altered bile acid metabolism which can be regulated by gut microbiota. Simultaneously, BAs also reshape gut microbiota and improve IR and T2DM in the bidirectional communications of the gut-liver axis. This article reviewed the findings on the interaction between BAs and gut microbiota in improving T2DM, which focused on gut microbiota and its debinding function and BAs regulated gut microbiota through FXR/TGR5. Meanwhile, BAs and their derivatives that are effective for improving T2DM and other treatments based on bile acid metabolism were also summarized. This review highlighted that BAs play a critical role in the glucose metabolism and may serve as therapeutic targets in T2DM, providing a reference for discovering and screening novel therapeutic drugs.

Pharmacological Effects of Secondary Bile Acid Microparticles in Diabetic Murine Model

AIM

Examine bile acids effects in Type 2 diabetes.

BACKGROUND

In recent studies, the bile acid ursodeoxycholic acid (UDCA) has shown potent antiinflammatory effects in obese patients while in type 2 diabetics (T2D) levels of the pro-inflammatory bile acid lithocholic acid were increased, and levels of the anti-inflammatory bile acid chenodeoxycholic acid were decreased, in plasma.

OBJECTIVE

Hence, this study aimed to examine applications of novel UDCA microparticles in diabetes.

METHODS

Diabetic balb/c adult mice were divided into three equal groups and gavaged daily with either empty microcapsules, free UDCA, or microencapsulated UDCA over two weeks. Their blood, tissues, urine, and faeces were collected for blood glucose, inflammation, and bile acid analyses. UDCA resulted in modulatory effects on bile acids profile without antidiabetic effects suggesting that bile acid modulation was not directly linked to diabetes treatment.

RESULTS

UDCA resulted in modulatory effects on bile acids profile without antidiabetic effects suggesting that bile acid modulation was not directly linked to diabetes treatment.

CONCLUSION

Bile acids modulated the bile profile without affecting blood glucose levels.

Bile acid-based dual-functional prodrug nanoparticles for bone regeneration through hydrogen peroxide scavenging and osteogenic differentiation of mesenchymal stem cells

A high level of reactive oxygen species (ROS) such as hydrogen peroxide (H₂O₂) upregulates pro-inflammatory cytokines and inhibits the osteogenic differentiation of mesenchymal stem cells (MSCs), which are key factors in bone regeneration. Ursodeoxycholic acid (UDCA), a hydrophilic bile acid, has antioxidant and anti-inflammatory activities and also plays beneficial roles in bone regeneration by stimulating the osteogenic differentiation of MSCs while suppressing their adipogenic differentiation. Despite its remarkable capacity for bone regeneration, multiple injections of UDCA induce adverse side effects such as mechanical stress and contamination in bone defects. To fully exploit the beneficial roles of UDCA, a concept polymeric prodrug was developed based on the hypothesis that removal of overproduced H₂O₂ will potentiate the osteogenic functions of UDCA. In this work, we report bone regenerative nanoparticles (NPs) formulated from a polymeric prodrug of UDCA (PUDCA) with UDCA incorporated in its backbone through H₂O₂-responsive peroxalate linkages. The PUDCA NPs displayed potent antioxidant and anti-inflammatory activities in MSCs and induced osteogenic rather than adipogenic differentiation of the MSCs. In rat models of bone defect, the PUDCA NPs exhibited significantly better bone regeneration capacity and anti-inflammatory effects than equivalent amounts of UDCA. We anticipate that PUDCA NPs have tremendous translational potential as bone regenerative agents.

Ursodeoxycholic acid abrogates gentamicin-induced hepatotoxicity in rats: Role of NF-κB-p65/TNF-α, Bax/Bcl-xl/Caspase-3, and eNOS/iNOS pathways

AIM

The present study focused on the possible underlying protective mechanisms of UDCA against GNT-induced hepatic injury.

METHODS

For achieving this goal, adult male rats were allocated into 4 groups: normal control (received vehicle), GNT (100 mg/kg, i.p. for 8 days), UDCA (60 mg/kg, P.O. for 15 days), and GNT + UDCA (received UDCA for 15 days and GNT started from the 7th day and lasted for 8 days).

RESULTS

The results revealed that UDCA significantly improved GNT-induced hepatic injury, oxidative stress, apoptosis, and inflammatory response. Interestingly, UDCA inhibited apoptosis by marked down-regulation of the Bax gene, Caspase-3, and cleaved Caspase-3 protein expressions while the level of Bcl-xL gene significantly increased. Moreover, UDCA strongly inhibited the inflammatory response through the down-regulation of both NF-κB-p65 and TNF-α accompanied by IL-10 elevation. Furthermore, the obtained results ended with the restored of mitochondria function that confirmed by electron microscopy. Histological analysis showed that UDCA remarkably ameliorated the histopathological changes induced by GNT.

SIGNIFICANCE

UDCA may be a promising agent that can be used to prevent hepatotoxicity observed in GNT treatment. This effect could be attributed to, at least in part, the ability of UDCA to modulate NF-κB-p65/TNF-α, Bax/Bcl-xl/Caspase-3, and eNOS/iNOS signaling pathways.

Modulatory Nano/Micro Effects of Diabetes Development on Pharmacology of Primary and Secondary Bile Acids Concentrations

BACKGROUND

Recent studies have suggested that hyperglycaemia influences the bile acid profile and concentrations of secondary bile acids in the gut.

INTRODUCTION

This study aimed to measure changes in the bile acid profile in the gut, tissues, and faeces in type 1 Diabetes (T1D) and Type 2 Diabetes (T2D).

METHODS

T1D and T2D were established in a mouse model. Twenty-one seven-weeks old balb/c mice were randomly divided into three equal groups, healthy, T1D and T2D. Blood, tissue, urine and faeces samples were collected for bile acid measurements.

RESULTS

Compared with healthy mice, T1D and T2D mice showed lower levels of the primary bile acid, chenodeoxycholic acid, in the plasma, intestine, and brain, and higher levels of the secondary bile acid, lithocholic acid, in the plasma and pancreas. Levels of the bile acid ursodeoxycholic acid were undetected in healthy mice but were found to be elevated in T1D and T2D mice.

CONCLUSION

Bile acid profiles in other organs were variably influenced by T1D and T2D development, which suggests similarity in effects of T1D and T2D on the bile acid profile, but these effects were not always consistent among all organs, possibly since feedback mechanisms controlling enterohepatic recirculation and bile acid profiles and biotransformation are different in T1D and T2D.

Betulin attenuated liver damage by prevention of hepatic mitochondrial dysfunction in rats with alcoholic steatohepatitis

Betulin, a pentacyclic triterpene, possesses antioxidant, anti-inflammatory and hepatoprotective properties. The aim of this study was to evaluate the impact of liver mitochondria in hepatoprotection of betulin using a rat model of alcoholic steatohepatitis induced by ethanol administration (4 g/kg, intragastric) for 8 weeks. The treatment with betulin (50 and 100 mg/kg b.w., intragastric) during this period attenuated the histological signs of steatohepatitis and lowered the serum and liver triglyceride contents, as well as the serum activities of aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase. Betulin (100 mg/kg) decreased the liver/body weight ratio and inhibited the increase in the serum levels of TNFα, IL-1β, TGFβ, and hyaluronic acid, demonstrating hepatoprotective, anti-inflammatory, and antifibrotic potential. Betulin also inhibited the formation of superoxide anions in mitochondria and the end-products of lipid peroxidation in liver tissue, the amount of which was significantly increased in ethanol-treated rats. The disturbances in mitochondrial respiration, uncoupling of oxidative phosphorylation and decreasing of mitochondrial complex I, II, and IV activities in rats with steatohepatitis, were reverted by betulin administration. The increased susceptibility of mitochondria to Ca2+-induced permeability transition pore formation in the hepatitis group was improved in rats treated with betulin. In conclusion, betulin, having antioxidant properties, exerts a beneficial effect in the rat model of alcoholic steatohepatitis via prevention of liver mitochondria dysfunction, which may be attributed to the inhibition of mitochondrial permeability transition.

Impact of ursodeoxycholic acid on circulating lipid concentrations: a systematic review and meta-analysis of randomized placebo-controlled trials

Objective

The aim of this meta-analysis of randomized placebo-controlled trials was to examine whether ursodeoxycholic acid treatment is an effective lipid-lowering agent.

Methods

PubMed-Medline, SCOPUS, Web of Science and Google Scholar databases were searched in order to find randomized controlled trials evaluating the effect of ursodeoxycholic acid on lipid profile. A random-effect model and the generic inverse variance weighting method were used for quantitative data synthesis. Sensitivity analysis was conducted using the leave-one-out method. A random-effects meta-regression model was performed to explore the association between potential confounders and the estimated effect size on plasma lipid concentrations.

Results

Meta-analysis of 20 treatment arms revealed a significant reduction of total cholesterol following ursodeoxycholic acid treatment (WMD: − 13.85 mg/dL, 95% CI: -21.45, − 6.25, p < 0.001). Nonetheless, LDL-C (WMD: -6.66 mg/dL, 95% CI: -13.99, 0.67, p = 0.075), triglycerides (WMD: − 1.42 mg/dL, 95% CI: -7.51, 4.67, p = 0.648) and HDL-C (WMD: -0.18 mg/dL, 95% CI: -5.23, 4.87, p = 0.944) were not found to be significantly altered by ursodeoxycholic acid administration. In the subgroup of patients with primary biliary cirrhosis, ursodeoxycholic acid reduced total cholesterol (WMD: − 29.86 mg/dL, 95% CI: -47.39, − 12.33, p = 0.001) and LDL-C (WMD: -37.27 mg/dL, 95% CI: -54.16, − 20.38, p < 0.001) concentrations without affecting TG and HDL-C.

Conclusion

This meta-analysis suggests that ursodeoxycholic acid therapy might be associated with significant total cholesterol lowering particularly in patients with primary biliary cirrhosis.

Ursodeoxycholic Acid Regulates Hepatic Energy Homeostasis and White Adipose Tissue Macrophages Polarization in Leptin-Deficiency Obese Mice

Obesity has been shown to play a role in the pathogenesis of several forms of metabolic syndrome, including non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes. Ursodeoxycholic acid (UDCA) has been shown to possess antioxidant and anti-inflammatory properties and prevents mitochondrial dysfunction in the progression of obesity-associated diseases. The aim of the study was to evaluate the mechanisms of UDCA during obesity-linked hepatic mitochondrial dysfunction and obesity-associated adipose tissue macrophage-induced inflammation in obese mice. UDCA significantly decreased lipid droplets, reduced free fatty acids (FFA) and triglycerides (TG), improved mitochondrial function, and enhanced white adipose tissue browning in ob/ob mice. This is associated with increased hepatic energy expenditure, mitochondria biogenesis, and incorporation of bile acid metabolism (Abca1, Abcg1 mRNA and BSEP, FGFR4, and TGR5 protein). In addition, UDCA downregulated NF-κB and STAT3 phosphorylation by negative regulation of the expression of SOCS1 and SOCS3 signaling. These changes were accompanied by decreased angiogenesis, as shown by the downregulation of VEGF, VCAM, and TGF-βRII expression. Importantly, UDCA is equally effective in reducing whole body adiposity. This is associated with decreased adipose tissue expression of macrophage infiltration (CD11b, CD163, and CD206) and lipogenic capacity markers (lipofuscin, SREBP-1, and CD36). Furthermore, UDCA significantly upregulated adipose browning in association with upregulation of SIRT-1-PGC1-α signaling in epididymis adipose tissue (EWAT). These results suggest that multi-targeted therapies modulate glucose and lipid biosynthesis fluxes, inflammatory response, angiogenesis, and macrophage differentiation. Therefore, it may be suggested that UDCA treatment may be a novel therapeutic agent for obesity.

Chemical induction of hepatic apoptosis in rodents

The urge of identifying new pharmacological interventions to prevent or attenuate liver injury is of critical importance and needs an expanded experimental toolbox. Hepatocyte injury and cellular death is a prominent feature behind the pathology of liver diseases. Several research activities focused on identifying chemicals and hepatotoxicants that induce cell death by apoptosis, in addition to presenting its corresponding signaling pathway. Although such efforts provided further understanding of the mechanisms of cell death, it has also raised confusion concerning identifying the involvement of several modes of cell death including apoptosis, necrosis and fibrosis. The current review highlights the ability of several chemicals and potential hepatotoxicants to induce liver damage in rodents by means of apoptosis while the probable involvement of other modes of cell death is also exposed. Thus, several chemical substances including hepatotoxins, mycotoxins, hyperglycemia inducers, metallic nanoparticles and immunosuppressant drugs are reviewed to explore the hepatic cytotoxic spectrum they could exert on hepatocytes of rodents. In addition, the current review address the mechanism by which hepatotoxicity is initiated in hepatocytes in different rodents aiding the researcher in choosing the right animal model for a better research outcome.

Potential Applications of Gliclazide in Treating Type 1 Diabetes Mellitus: Formulation with Bile Acids and Probiotics

A major advancement in therapy of type 1 diabetes mellitus (T1DM) is the discovery of new treatment which avoids and even replaces the absolute requirement for injected insulin. The need for multiple drug therapy of comorbidities associated with T1DM increases demand for developing novel therapeutic alternatives with new mechanisms of actions. Compared to other sulphonylurea drugs used in the treatment of type 2 diabetes mellitus, gliclazide exhibits a pleiotropic action outside pancreatic β cells, the so-called extrapancreatic effects, such as antiinflammatory and cellular protective effects, which might be beneficial in the treatment of T1DM. Results from in vivo experiments confirmed the positive effects of gliclazide in T1DM that are even more pronounced when combined with other hypoglycaemic agents such as probiotics and bile acids. Even though the exact mechanism of interaction at the molecular level is still unknown, there is a clear synergistic effect between gliclazide, bile acids and probiotics illustrated by the reduction of blood glucose levels and improvement of diabetic complications. Therefore, the manipulation of bile acid pool and intestinal microbiota composition in combination with old drug gliclazide could be a novel therapeutic approach for patients with T1DM.

High-Loading Dose of Microencapsulated Gliclazide Formulation Exerted a Hypoglycaemic Effect on Type 1 Diabetic Rats and Incorporation of a Primary Deconjugated Bile Acid, Diminished the Hypoglycaemic Antidiabetic Effect

BACKGROUND AND OBJECTIVE

Gliclazide is a drug commonly used in type 2 diabetes mellitus. Recently, gliclazide has shown desirable pharmacological effects such as immunoregulatory and anti-clotting effects, which suggests potential applications in type 1 diabetes mellitus (T1DM). Gliclazide has variable absorption after oral administration, and thus using targeted-delivery techniques, such as microencapsulation, may optimise gliclazide absorption and potential applications in T1DM. Bile acids such as cholic acid have shown microcapsule-stabilising and controlled-release effects, and thus their incorporation into gliclazide microcapsules may further optimise gliclazide release, absorption and antidiabetic effects. Accordingly, this study aimed to examine the hypoglycaemic effects of gliclazide microcapsules with and without cholic acid, in a rat model of T1DM.

METHODS

Thirty-five alloxan-induced T1DM rats were randomly divided into five equal groups and gavaged a single dose of empty microcapsules, gliclazide, gliclazide microcapsules, gliclazide-cholic acid or gliclazide-cholic acid microcapsules. Blood samples were collected over 10 h post-dose and analysed for blood glucose and gliclazide serum concentrations.

RESULTS

Gliclazide microcapsules exerted a hypoglycaemic effect in the diabetic rats, and cholic acid incorporation diminished the hypoglycaemic effects, which suggests the lack of synergistic effects between gliclazide and cholic acid. In addition, neither microencapsulation nor cholic acid incorporation optimised gliclazide absorption which suggests that hypoglycaemic effects of gliclazide are independent of its absorption and serum concentrations. This also suggests that hypoglycaemic effects of gliclazide may be associated with gut-metabolic activation rather than gut-targeted delivery and systemic absorption.

CONCLUSION

Gliclazide microcapsules exerted hypoglycaemic effects in T1DM rats independent of insulin and thus may have potentials in treatment of T1DM.

The roles of bile acids and applications of microencapsulation technology in treating Type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) is an autoimmune disease characterized by the loss of glycemic control. Recent studies have shown significant inflammation and disturbed bile acid homeostasis, associated with T1DM. Bile acids are endogenously produced as a result of cholesterol catabolism in the liver and solely metabolized by gut microflora. This review investigates their potential oral delivery in T1DM using targeted delivery and encapsulation technologies. A sensitive and selective search was carried out using different search engines and databases. Keywords used included diabetes mellitus, bile acids and inflammation. To conclude, bile acids have a significant impact on diabetes symptoms and, when microencapsulated, may be used as an adjunct therapy to supplement T1DM treatment.

Ursodeoxycholic acid decreases age-related adiposity and inflammation in mice

Ursodeoxycholic acid (UDCA), a natural, hydrophilic nontoxic bile acid, is clinically effective for treating cholestatic and chronic liver diseases. We investigated the chronic effects of UDCA on age-related lipid homeostasis and underlying molecular mechanisms. Twenty-week-old C57BL/6 male and female mice were fed a diet with or without 0.3% UDCA supplementation for 25 weeks. UDCA significantly reduced weight gain, adiposity, hepatic triglyceride, and hepatic cholesterol without incidental hepatic injury. UDCA-mediated hepatic triglyceride reduction was associated with downregulated hepatic expression of peroxisome proliferator-activated receptor-γ, and of other genes involved in lipogenesis (Chrebp, Acaca, Fasn, Scd1, and Me1) and fatty acid uptake (Ldlr, Cd36). The inflammatory cytokines Tnfa, Ccl2, and Il6 were significantly decreased in liver and/or white adipose tissues of UDCA-fed mice. These data suggest that UDCA exerts beneficial effects on age-related metabolic disorders by lowering the hepatic lipid accumulation, while concurrently reducing hepatocyte and adipocyte susceptibility to inflammatory stimuli. [BMB Reports 2016; 49(2): 105-110]

Amelioration of Hyperglycaemia, Oxidative Stress and Dyslipidaemia in Alloxan-Induced Diabetic Wistar Rats Treated with Probiotic and Vitamin C

Clinical and experimental evidence suggests that hyperglycaemia is responsible for the oxidative stress in diabetes mellitus. The study was designed to investigate the comparative effects of probiotic and vitamin C (Vit-C) treatments on hyperglycaemia, oxidative stress and dyslipidaemia in alloxan-induced diabetic rats. Type 1 diabetes (T1DM) was induced in male Wistar rats by a single intraperitoneal (i.p.) injection of alloxan (150 mg/kg). Six groups of the animals received the following treatment regimens for four weeks: (1) Normal saline, per os; (2) alloxan (150 mg/kg, i.p.); (3) alloxan (150 mg/kg) + insulin (4 U/kg, subcutaneously); (4) alloxan (150 mg/kg) + probiotic (4.125 × 10⁶ CFU/100 mL per os); (5) alloxan (150 mg/kg) + Vit-C (100 mg/kg, i.m.); (6) alloxan (150 mg/kg) + probiotic (4.125 × 10⁶ CFU/100 mL per os) + Vit-C (100 mg/kg, intramuscularly). Probiotic + Vit-C decreased (p < 0.05) blood glucose concentration in diabetic treated group, when compared with the untreated diabetic group. Probiotic + Vit-C reduced malondialdehyde concentration, in the serum, brain and kidneys, respectively, but increased the activity of antioxidant enzymes. Probiotic and Vit-C may be more effective than Vit-C alone, in ameliorating hyperglycaemia, oxidative stress and dyslipidaemia in alloxan-induced diabetic rats.

Effect of Solanum surattense on mitochondrial enzymes in diabetic rats and in vitro glucose uptake activity in L6 myotubes

BACKGROUND

S. surattense is widely used in Siddha medicine for various ailments.

OBJECTIVE

The aim was to evaluate the impact of alcoholic leaf-extract of S. surattense on mitochondrial enzymes in streptozotocin (STZ) induced diabetic rats and to study the in vitro muscle glucose uptake activity on L6 myotubes.

MATERIALS AND METHODS

The male albino Wistar rats were randomly divided into five groups of six animals each. Diabetes was induced by intraperitoneal injection of STZ (40 mg/kg body weight). After being confirmed the diabetic rats were treated with alcoholic leaf-extract of S. surattense (100 mg/kg body weight) for 45 days. The biochemical estimations (liver mitochondrial enzymes, antioxidants, thiobarbituric acid reactive substances [TBARS]) and histopathological studies were performed. Further, the in vitro muscle glucose uptake activity in L6 myotubes and messenger RNA (mRNA) expression of glucose transporter-4 (GLUT-4) was performed.

RESULTS

In diabetic rats, the activities of liver mitochondrial enzymes were found to be significantly lowered. The mitochondrial TBARS level increased, whereas the activities/level of enzymatic and non-enzymatic antioxidants decreased in diabetic rats. Administration of S. surattense to diabetic rats significantly reversed the above parameters toward normalcy. Furthermore in diabetic rats, the histopathological studies showed growth of adipose tissue and shrinkage of islets in the pancreas, liver showed fatty change with mild inflammation of portal triad, and kidney showed messangial capillary proliferation of glomeruli and fatty infiltration of tubules. Treatment with S. surattense brought back these changes to near normalcy. The extract was analyzed for in vitro muscle glucose uptake activity in L6 myotubes and mRNA expression of GLUT-4 by semi-quantitative reverse transcriptase-polymerase chain reaction. One nano gram per millilitre of S. surattense leaf-extract gave 115% glucose uptake on L6 myotubes. It also showed elevated levels of GLUT-4 mRNA transcripts, when compared with control cells.

CONCLUSION

These studies strongly support the anti-diabetic nature of S. surattense.

Protective effects of dietary avocado oil on impaired electron transport chain function and exacerbated oxidative stress in liver mitochondria from diabetic rats

Electron transport chain (ETC) dysfunction, excessive ROS generation and lipid peroxidation are hallmarks of mitochondrial injury in the diabetic liver, with these alterations also playing a role in the development of non-alcoholic fatty liver disease (NAFLD). Enhanced mitochondrial sensitivity to lipid peroxidation during diabetes has been also associated to augmented content of C22:6 in membrane phospholipids. Thus, we aimed to test whether avocado oil, a rich source of C18:1 and antioxidants, attenuates the deleterious effects of diabetes on oxidative status of liver mitochondria by decreasing unsaturation of acyl chains of membrane lipids and/or by improving ETC functionality and decreasing ROS generation. Streptozocin-induced diabetes elicited a noticeable increase in the content of C22:6, leading to augmented mitochondrial peroxidizability index and higher levels of lipid peroxidation. Mitochondrial respiration and complex I activity were impaired in diabetic rats with a concomitant increase in ROS generation using a complex I substrate. This was associated to a more oxidized state of glutathione, All these alterations were prevented by avocado oil except by the changes in mitochondrial fatty acid composition. Avocado oil did not prevented hyperglycemia and polyphagia although did normalized hyperlipidemia. Neither diabetes nor avocado oil induced steatosis. These results suggest that avocado oil improves mitochondrial ETC function by attenuating the deleterious effects of oxidative stress in the liver of diabetic rats independently of a hypoglycemic effect or by modifying the fatty acid composition of mitochondrial membranes. These findings might have also significant implications in the progression of NAFLD in experimental models of steatosis.

Hypoglycemic activity and acute oral toxicity of chromium methionine complexes in mice

The hypoglycemic activity of chromium methionine (CrMet) in alloxan-induced diabetic (AID) mice was investigated and compared with those of chromium trichloride hexahydrate (CrCl3·6H2O) and chromium nicotinate (CrNic) through a 15-day feeding experiment. The acute oral toxicity of CrMet was also investigated in ICR (Institute for Cancer Research) mice by a single oral gavage. The anti-diabetic activity of CrMet was explored in detail from the aspects of body weight (BW), blood glucose, triglyceride, total cholesterol, liver glycogen levels, aspartate transaminase (AST) and alanine transaminase (ALT) levels. The obtained results showed that CrMet had beneficial effects on glucose and lipid metabolism, and might possess hepatoprotective efficacy for diabetes. Daily treatment with 500 and 1000μg Cr/kg BW of CrMet in AID mice for 15 days indicated that this low-molecular-weight organic chromium complex had better bioavailability and more beneficial effects on diabetics than CrCl3·6H2O. CrMet also had advantage over CrNic in the control of AST and ALT activities. Acute toxicity studies revealed that CrMet had low toxicity potential and relatively high safety margins in mice with the LD50 value higher than 10.0g/kg BW. These findings suggest that CrMet might be of potential value in the therapy and protection of diabetes.

Ursodeoxycholic acid decreases sodium-glucose cotransporter (SGLT2) expression and oxidative stress in the kidney of diabetic rats

Oxidative stress has been associated with diabetic complications like nephropathies. Recent studies indicate that ursodeoxycholic acid (UDCA) may be beneficial preventing diabetes-induced oxidative stress and secondary complications. Thus, we study if the UDCA-treatment decreases the expression of sodium-glucose cotransporter (SGLT2) and the oxidative stress in the kidney of diabetic rats.

METHODS

The diabetes model was established by intraperitoneal injection of streptozotocin (50mg/kg). SGLT2 expression was evaluated by western blot and RT-PCR. Oxidative stress was assessed by catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase activities (SOD) and immunohistochemical analysis of 3-nitrotyrosine (3-NT).

RESULTS

Streptozotocin-induced diabetes caused hyperglycemia and lower body weight. The SGLT2 expression and mRNA levels increased in cortex of kidney from diabetic rats. The CAT activity decreased in cortex and medulla from diabetic rats, otherwise the GPx activity increased. Furthermore the 3-NT staining of kidney from diabetic rats increased compared to control rats. The UDCA treatment was able to decrease hyperglycemia and prevents the SGLT2 over-expression, restores the CAT and GPX activities and decreases 3-NT staining.

CONCLUSION

The UDCA treatment prevents the over-expression of SGLT2 and oxidative stress in kidney of diabetic rats.

Enhanced anti-diabetic activity of a combination of chromium(III) malate complex and propolis and its acute oral toxicity evaluation

In order to obtain the additional benefit of anti-diabetic activity and protective effects of liver injury for diabetes, the anti-diabetic effect and acute oral toxicity of a combination of chromium(III) malate complex (Cr(2)(LMA)(3)) and propolis were assessed. The anti-diabetic activity of the combination of the Cr(2)LMA(3) and propolis was compared with Cr(2)(LMA)(3) and propolis alone in alloxan-induced diabetic mice by daily oral gavage for a period of 2 weeks. Acute oral toxicity of the combination of the Cr(2)LMA(3) and propolis was tested using ICR mice at the dose of 1.0-5.0 g/kg body mass by a single oral gavage and observed for a period of 2 weeks. The results of the anti-diabetic activity of the combination from the aspects of blood glucose level, liver glycogen level, and the activities of aspartate transaminase, alanine transaminase, and alkaline phosphatase indicated that the increased anti-diabetic activity and the protective efficacy of liver injury for diabetes were observed. In acute toxicity study, LD(50) (median lethal dose) value for the combination was greater than 5.0 g/kg body mass. The combination of Cr(2)LMA(3) and propolis might represent the nutritional supplement with potential therapeutic value to control blood glucose and exhibit protective efficacy of liver injury for diabetes and non-toxicity in acute toxicity.

Ursodeoxycholic acid treatment of hepatic steatosis: a (13)C NMR metabolic study

Ursodeoxycholic acid (UDCA) is commonly used for the treatment of hepatobiliary disorders. In this study, we tested whether a 4-week treatment with this bile acid (12-15 mg/kg/day) could improve hepatic fatty acid oxidation in obese Zucker rats - a model for nonalcoholic fatty liver disease and steatosis. After 24 h of fasting, livers were perfused with physiological concentrations of [U-(13) C]nonesterified fatty acids and [3-(13) C]lactate/[3-(13) C]pyruvate. Steatosis was associated with abundant intracellular glucose, lactate, alanine and methionine, and low concentrations of choline and betaine. Steatotic livers also showed the highest output of glucose and lactate. Glucose and glycolytic products were mostly unlabeled, indicating active glycogenolysis and glycolysis after 24 h of fasting. UDCA treatment resulted in a general amelioration of liver metabolic abnormalities with a decrease in intracellular glucose and lactate, as well as their output. Hepatic betaine and methionine were also normalized after UDCA treatment, suggesting the amelioration of anti-oxidative defenses. Choline levels were not affected by the bile acid, which may indicate a deficient synthesis of very-low-density lipoproteins. The percentage contribution of [U-(13) C]nonesterified fatty acids to acetyl-coenzyme A entering the tricarboxylic acid (TCA) cycle was significantly lower in livers from Zucker obese rats relative to control rats: 23.1 ± 4.9% versus 44.1 ± 2.7% (p < 0.01). UDCA treatment did not alter significantly fatty acid oxidation in control rats, but improved significantly oxidation in Zucker obese rats to 46.0 ± 6.1% (p > 0.05), comparable with control group values. The TCA cycle activity subsequent to fatty acid oxidation was reduced in steatotic livers and improved when UDCA was administered (0.24 ± 0.04 versus 0.37 ± 0.05, p = 0.05). We further suggest that the mechanism of action of UDCA is either related to the activity of the farnesoid receptor, or to the amelioration of the anti-oxidative defenses and cell nicotinamide adenine dinucleotide (NAD(+) /NADH) ratio, favoring TCA cycle activity and β-oxidation.

Early hyperglycemia following alloxan administration in vivo is not associated with altered hepatic mitochondrial function: acceptable model for type 1 diabetes?

Alloxan and oxidative stress, which have been detected in livers of laboratory animals shortly after in vivo alloxan administration, cause in vitro mitochondrial dysfunction, thus questioning alloxan diabetes as an acceptable model for type 1 diabetes, a model that cannot legitimately be used to investigate mitochondrial metabolism in a diabetic state. In the current study, the blood glucose concentration increased in the drug-treated group of Sprague–Dawley rats (compared with the placebo group) 45 or 60 min after alloxan treatment, whereas at 30 min the blood glucose concentration was unchanged. State 4, state 3, respiratory control, efficiency of oxidative phosphorylation, and mitochondrial ATP synthase activity, assayed using glutamate plus malate, pyruvate plus malate, or succinate as a substrate, were not negatively altered during the entire study. These results indicated that early increases of blood glucose concentration, after in vivo alloxan administration, did not lead to liver mitochondrial dysfunction, suggesting that alloxan diabetes can be used for the study of liver mitochondrial respiration in a diabetic state.

Double antioxidant activities of rosiglitazone against high glucose-induced oxidative stress in hepatocyte

Chronic hyperglycemia is the hallmark of diabetes and its complication. High glucose-induced excessive reactive oxygen species (ROS) production has been considered to play an important role in the development of diabetes. However, the influence of high glucose on the liver remains to be clarified. Rosiglitazone (RSG) is a member of thiazolidinediones (TDZs) family, which is the ligand of the of nuclear transcription factor peroxisome proliferator-activated receptor-γ (PPARγ), being used clinically for the treatment of type 2 diabetic patients through their insulin-sensitizing effect. In the present study, we investigated the cytotoxicity of high glucose in QZG hepatocytes and evaluated the protective effect of RSG. The results showed that high glucose significantly reduced cell viability through generation of ROS via activation of PKC, which was inhibited by RSG. On the one hand, RSG notably inhibited the activation of PKC induced by high glucose independent of PPARγ, leading to the decrease of ROS generation. On the other hand, RSG notably increased the expression of key antioxidant transcription factor Nrf2 and antioxidant enzyme HO-1 in a PPARγ-dependent manner, leading to the elimination of excessive ROS. In addition, RSG also inhibited the decrease of COX-2 expression induced by high glucose through activating PPARγ. Furthermore, the activation of Akt and MAPKs was involved in the effect of RSG on Nrf2, HO-1 and COX-2. In summary, our study supports the hypothesis that RSG protect hepatocytes from high glucose-induced toxicity through PPARγ-dependent and PPARγ-independent pathways.

The correlation between NF-κB inhibition and disease activity by coadministration of silibinin and ursodeoxycholic acid in experimental colitis

NF-κB is one of the most important nuclear factors responsible for overexpression of proinflammatory cytokines. This is demonstrated by increased NF-κB activity and other dependent immune factors in inflammatory bowel disease (IBD). Anti-inflammatory effects of silibinin and ursodeoxycholic acid (UDCA) along with their NF-κB inhibitory property are thought to be beneficial in colitis. Trinitrobenzene sulfonic acid was used to induce colitis rat models. After instillation, 48 rats were treated with oral silibinin, UDCA alone or a combination of both. Intraperitoneal dexamethasone was used in the control group. After 12 days of treatment, colonic samples were tested for the severity of mucosal damage macroscopically and microscopically. The levels of activated NF-κB, IL-1β, TNF-α, myeloperoxidase, thiobarbituric acid reactive substances (TBARS), protein carbonyl, and the antioxidant power of the bowel homogenates were determined. The results indicated a significant reduction in NF-κB activity as well as the levels of IL-1β, TNF-α, TBARS, protein carbonyl, myeloperoxidase activity, and an improvement in antioxidant power of colitis in treated rats. Combination therapy resulted in a more prominent improvement in bowel antioxidant power and myeloperoxidase activity. In conclusion, combination of silibinin and UDCA by inhibition of NF-κB and other relevant inflammatory factors of colitis is a good candidate for management of Crohn's disease.

Changes in hepatic gene expression upon oral administration of taurine-conjugated ursodeoxycholic acid in ob/ob mice

Nonalcoholic fatty liver disease (NAFLD) is highly prevalent and associated with considerable morbidities. Unfortunately, there is no currently available drug established to treat NAFLD. It was recently reported that intraperitoneal administration of taurine-conjugated ursodeoxycholic acid (TUDCA) improved hepatic steatosis in ob/ob mice. We hereby examined the effect of oral TUDCA treatment on hepatic steatosis and associated changes in hepatic gene expression in ob/ob mice. We administered TUDCA to ob/ob mice at a dose of 500 mg/kg twice a day by gastric gavage for 3 weeks. Body weight, glucose homeostasis, endoplasmic reticulum (ER) stress, and hepatic gene expression were examined in comparison with control ob/ob mice and normal littermate C57BL/6J mice. Compared to the control ob/ob mice, TUDCA treated ob/ob mice revealed markedly reduced liver fat stained by oil red O (44.2±5.8% vs. 21.1±10.4%, P<0.05), whereas there was no difference in body weight, oral glucose tolerance, insulin sensitivity, and ER stress. Microarray analysis of hepatic gene expression demonstrated that oral TUDCA treatment mainly decreased the expression of genes involved in de novo lipogenesis among the components of lipid homeostasis. At pathway levels, oral TUDCA altered the genes regulating amino acid, carbohydrate, and drug metabolism in addition to lipid metabolism. In summary, oral TUDCA treatment decreased hepatic steatosis in ob/ob mice by cooperative regulation of multiple metabolic pathways, particularly by reducing the expression of genes known to regulate de novo lipogenesis.