Effect of alcohol on blood glucose and antioxidant enzymes in the liver and kidney of diabetic rats

Alcohol promotes liver fibrosis in high fat diet induced diabetic rats

OBJECTIVES

Type 2 diabetes (T2DM) and alcoholism are considered to be lifestyle-associated independent risk factors in fatty liver diseases (FLD) mediated cirrhosis and hepatocellular carcinoma (HCC). A combined effect of both these conditions may exacerbate the pathological changes and a pre-clinical exploration of this is expected to provide a mechanical detail of the pathophysiology. The present study aims to understand the effect of alcohol on pre- diabetic and type 2 diabetic female Wistar rats.

METHODS

In this experimental study, 12 Wistar rats (180-220 g) were randomly assigned into three groups: Normal (fed normal rat chow), alcohol (20 %) fed diabetic (HFD + STZ), and pre-diabetic rats (HFD alone). After, two months of the experimental period, blood and liver tissues were collected lipid metabolic alteration, liver injury, and fibrosis were determined following biochemical and histological methods. Data were analyzed using one-way ANOVA and Dunnett's Post Hoc test.

RESULTS

Significant dyslipidemia was observed in the liver tissues of diabetic and pre-diabetic rats following alcohol ingestion. A significant (p<0.05) increase in lipid peroxidation status, and hepatic marker enzyme activities (p<0.0001) were observed in diabetic animals. In corroborating with these observations, hematoxylin and eosin staining of hepatic tissue revealed the presence of sinusoidal dilation along with heavily damaged hepatocytes and inflammatory cell infiltration. Further, significantly (p<0.001) increased hepatic hydroxyproline content and extended picrosirius red stained areas of collagen in liver tissue indicated initiation of fibrosis in alcohol-fed diabetic rats.

CONCLUSIONS

Overall, the results indicate that alcohol consumption in T2DM conditions is more deleterious than pre diabetic conditions in progressing to hepatic fibrosis.

Mitochondrial dysfunction: A promising therapeutic target for liver diseases

The liver is an important metabolic and detoxification organ and hence demands a large amount of energy, which is mainly produced by the mitochondria. Liver tissues of patients with alcohol-related or non-alcohol-related liver diseases contain ultrastructural mitochondrial lesions, mitochondrial DNA damage, disturbed mitochondrial dynamics, and compromised ATP production. Overproduction of mitochondrial reactive oxygen species induces oxidative damage to mitochondrial proteins and mitochondrial DNA, decreases mitochondrial membrane potential, triggers hepatocyte inflammation, and promotes programmed cell death, all of which impair liver function. Mitochondrial DNA may be a potential novel non-invasive biomarker of the risk of progression to liver cirrhosis and hepatocellular carcinoma in patients infected with the hepatitis B virus. We herein present a review of the mechanisms of mitochondrial dysfunction in the development of acute liver injury and chronic liver diseases, such as hepatocellular carcinoma, viral hepatitis, drug-induced liver injury, alcoholic liver disease, and non-alcoholic fatty liver disease. This review also discusses mitochondrion-centric therapies for treating liver diseases.

Antioxidant therapy for hepatic diseases: a double-edged sword

Liver diseases are complex conditions, significantly influenced by oxidative stress. This comprehensive review assesses the therapeutic role of antioxidants like l-ascorbic acid and α tocopherol, beta-carotene, various minerals, and plant-based ingredients in mitigating oxidative stress-induced liver diseases. The manuscript delves into the critical influence of genetic and epigenetic factors on disease susceptibility, progression, and response to antioxidant therapy. While animal studies suggest antioxidant efficacy in liver disease treatment, human trials remain inconclusive, and caution is advised due to its possible potential pro-oxidant effects. Moreover, the interactions of antioxidants with other drugs necessitate careful consideration in the management of polypharmacy in liver disease patients. The review underscores the need for further research to establish the clinical benefits of antioxidants with understanding of possible antioxidant toxicities to elucidate the intricate interplay of genetic, epigenetic, and environmental factors in liver diseases. The aim is to foster a better understanding of the knowledge on hepatic disease management with judicial antioxidant therapies.

Endoplasmic reticulum stress in the pathogenesis of alcoholic liver disease

The endoplasmic reticulum (ER) plays a pivotal role in protein synthesis, folding, and modification. Under stress conditions such as oxidative stress and inflammation, the ER can become overwhelmed, leading to an accumulation of misfolded proteins and ensuing ER stress. This triggers the unfolded protein response (UPR) designed to restore ER homeostasis. Alcoholic liver disease (ALD), a spectrum disorder resulting from chronic alcohol consumption, encompasses conditions from fatty liver and alcoholic hepatitis to cirrhosis. Metabolites of alcohol can incite oxidative stress and inflammation in hepatic cells, instigating ER stress. Prolonged alcohol exposure further disrupts protein homeostasis, exacerbating ER stress which can lead to irreversible hepatocellular damage and ALD progression. Elucidating the contribution of ER stress to ALD pathogenesis may pave the way for innovative therapeutic interventions. This review delves into ER stress, its basic signaling pathways, and its role in the alcoholic liver injury.

Ginger Root Extract Improves GI Health in Diabetic Rats by Improving Intestinal Integrity and Mitochondrial Function

Background Emerging research suggests hyperglycemia can increase intestinal permeability. Ginger and its bioactive compounds have been reported to benefit diabetic animals due to their anti-inflammatory and antioxidant properties. In this study, we revealed the beneficial effect of gingerol-enriched ginger (GEG) on intestinal health (i.e., barrier function, mitochondrial function, and anti-inflammation) in diabetic rats. Methods Thirty-three male Sprague Dawley rats were assigned to three groups: low-fat diet (control group), high-fat-diet (HFD) + streptozotocin (single low dose 35 mg/kg body weight (BW) after 2 weeks of HFD feeding) (DM group), and HFD + streptozotocin + 0.75% GEG in diet (GEG group) for 42 days. Glucose tolerance tests (GTT) and insulin tolerance tests (ITT) were conducted at baseline and prior to sample collection. Total pancreatic insulin content was determined by ELISA. Total RNA of intestinal tissues was extracted for mRNA expression using qRT-PCR. Results Compared to the DM group, the GEG group had improved glucose tolerance and increased pancreatic insulin content. Compared to those without GEG (DM group), GEG supplementation (GEG group) increased the gene expression of tight junction (Claudin-3) and antioxidant capacity (SOD1), while it decreased the gene expression for mitochondrial fusion (MFN1), fission (FIS1), biogenesis (PGC-1α, TFAM), mitophagy (LC3B, P62, PINK1), and inflammation (NF-κB). Conclusions Ginger root extract improved glucose homeostasis in diabetic rats, in part, via improving intestinal integrity and mitochondrial dysfunction of GI health.

The acute effect of thiamine on serum insulin levels and some biochemical parameters in excessive alcohol-consuming rats

There are studies that present metabolic disorders in alcohol drinkers are associated with thiamine deficiency. Therefore, in the present study, it was aimed to investigate the effectiveness of thiamine in rats with binge drinking model. For this purpose, total 21 spraque dawley rats were divided into three equal groups as control, alcohol and thiamine+alcohol groups. The thiamine+ethanol group was given thiamine at a daily dose of 100 mg/kg by oral gavage, starting 2 days before the ethanol administration. Alcohol and thiamine+alcohol groups were given 3.45g/kg/day ethanol as 20%. At the end of the study, while serum total bile acid, total bilirubin and insulin levels increased in rats in the alcohol group compared to the rats in the control group; total protein and albumin levels decreased (P&lt;0.05). In the thiamine + alcohol group, LDL-cholesterol, total cholesterol, bile acid levels and AST enzyme activity increased, while ALT enzyme activity and total protein levels decreased compared to the control group (P&lt;0.05). There was no statistically significant result in the values in the thiamine+alcohol group compared to the alcohol group. It has been concluded that acutely administered thiamine supplementation had no effect on alcohol-induced biochemical parameter changes in binge-drinking animals. In this sense, studies with longer-term thiamine use are needed.

Synthesis and preparation of vitamin A coupled butein-loaded solid lipid nanoparticles for liver fibrosis therapy in rats

The development of a therapeutic system for hepatic fibrosis has become a research hotspot to date. Butein, a simple chalcone derivative, displays anti-fibrotic effects through different pathways. However, impurities, low solubility, and low concentration in the target tissue hinder therapy with herbal ingredients. Hepatic stellate cells (HSCs), the vitamin A (VA) storage cells, as the main contributors to liver fibrogenesis, are not readily accessible to drugs owing to their anatomical location. Targeted delivery of therapeutics to the activated HSCs is therefore critical for successful treatment. For these reasons, the current study aimed at increasing butein delivery to the liver. Hence, high purity butein was synthesized in three steps. A novel VA-Myrj52 ester conjugate was also synthesized using all-trans retinoic acid and a hydrophilic emulsifier (Myrj52) as a targeting agent. Next, butein was encapsulated inside the novel VA-modified solid lipid nanoparticles (VA-SLNs) and studied in vitro and in vivo. According to our evaluations, negatively charged SLNs with a mean diameter of 150 nm and entrapment efficacy of 75 % were successful in liver fibrosis amelioration. Intraperitoneal (i.p.) injection of VA-SLNs in fibrotic rats, for four weeks long, reduced serum AST and ALT by 58% (P, 0.001) and 72% (P, 0.05), respectively, concerning the CCl₄ group. Additionally, histologic damage score decline and normalization of tissue oxidative stress markers collectively confirmed the efficacy of formulations in hepatic fibrosis and kidney damage amelioration.

Oxidative Stress, Genomic Integrity, and Liver Diseases

Excess reactive oxygen species production and free radical formation can lead to oxidative stress that can damage cells, tissues, and organs. Cellular oxidative stress is defined as the imbalance between ROS production and antioxidants. This imbalance can lead to malfunction or structure modification of major cellular molecules such as lipids, proteins, and DNAs. During oxidative stress conditions, DNA and protein structure modifications can lead to various diseases. Various antioxidant-specific gene expression and signal transduction pathways are activated during oxidative stress to maintain homeostasis and to protect organs from oxidative injury and damage. The liver is more vulnerable to oxidative conditions than other organs. Antioxidants, antioxidant-specific enzymes, and the regulation of the antioxidant responsive element (ARE) genes can act against chronic oxidative stress in the liver. ARE-mediated genes can act as the target site for averting/preventing liver diseases caused by oxidative stress. Identification of these ARE genes as markers will enable the early detection of liver diseases caused by oxidative conditions and help develop new therapeutic interventions. This literature review is focused on antioxidant-specific gene expression upon oxidative stress, the factors responsible for hepatic oxidative stress, liver response to redox signaling, oxidative stress and redox signaling in various liver diseases, and future aspects.

Can we reduce oxidative stress with liver transplantation?

Background

The aim of this study was to determine the levels of lipid peroxidation (MDA) and antioxidants such as reduced glutathione (GSH), catalase (CAT) and superoxide dismutase (SOD) in the blood serum of patients with cirrhosis and liver transplantation.

Methods

In this study, serum malondialdehyde acid (MDA) levels, superoxide dismutase (SOD), reduced glutathione (GSH), and catalase (CAT) activities were measured spectrophotometrically and compared to the results of the healthy control group.

Results

SOD, CAT and GSH activities were significantly decreased in the patient groups compared to the healthy control group (p<0.05). MDA levels were significantly higher in the patient group compared to the healthy control group (p <0.05).

Conclusions

In conclusion, this study demonstrated that oxidative stress may play an important role in the development of liver cirrhosis and in liver transplantation. This study is the first one to show how MDA, SOD, CAT and GSH levels change in liver cirrhosis and liver transplantation, while further studies are essential to investigate antioxidant enzymes and oxidative stress status in patients with cirrhosis and liver transplantation.

N-acetylcysteine relieves neurologic signs of acute ethanol hangover in rats

Introduction: Alcohol abuse is one of the grave social and medical problems in many countries, including Russia. Alcohol not only negatively affects health, social and family relationships, but also a person’s performance. Hangover, which is a one of the negative consequences of alcohol intake, is a complex of neurological and somatic symptoms that occur when ethanol is almost completely metabolized to acetaldehyde. This condition, despite the severity and potential economic damage, remains poorly understood, and there are no effective medicines to treat it.

Aim: to provide an experimental basis for the possibility of using N-acetylcysteine (NAC), a precursor of glutathione, as a medicine for prevention of the neurological and cognitive impairments due to alcohol intoxication.

Materials and Methods: The study used male Wistar rats, which were intraperitoneally injected with ethanol at a dose of 3 g/kg to simulate acute ethanol intoxication. Sixty minutes before the injection, the animals from the experimental groups were gavaged with NAC (1 g/kg) or with an equivalent volume of saline. Immediately after awakening and 3 h after it, the animals were assessed for neurological deficits, motor skills, spontaneous motor activity, and cognitive functions. After the completion of the behavioral tests, the animals were euthanized to assess the level of glutathione, triglycerides (TGs), and malonic dialdehyde (MDA) in liver homogenates, and to determine the activity of enzymatic antioxidant systems and serum aminotransferases.

Results and Discussion: The ethanol intoxication in the animals from the control group was associated with pronounced signs of neurological and cognitive impairments, including low spontaneous motor and exploratory activity, impaired fine motor skills in the adhesive test, and cognitive function decline in the Morris water maze test. The rats which had received NAC before ethanol injection demonstrated better fine motor skills in the adhesive test, a higher level of spontaneous motor activity and better performance in the Morris water maze test (in comparison to the animals treated with saline before alcohol intoxication). In the animals which had received NAC, the levels of glutathione, MDA, and TGs, as well as the activity of liver antioxidant enzymes, were closer to the values of the intact rats to a greater extent than in the animals that had been injected with ethanol and received saline.

Conclusion: Orally administered NAC before acute ethanol intoxication led to a decrease in the severity of neurological deficiency in rats and reduced the amnesic effect of ethanol. This could be due to an improvement of ethanol metabolism and a decrease in the severity of disorders associated with oxidative stress and liver dysfunction.

The possible role of CREB-BDNF signaling pathway in neuroprotective effects of minocycline against alcohol-induced neurodegeneration: molecular and behavioral evidences

Abuse of alcohol triggers neurodegeneration in human brain. Minocycline has characteristics conferring neuroprotection. Current study evaluates the role of the CREB-BDNF signaling pathway in mediating minocycline's neuroprotective effects against alcohol-induced neurodegeneration. Seventy adult male rats were randomly split into groups 1 and 2 that received saline and alcohol (2 g/kg/day by gavage, once daily), respectively, and groups 3, 4, 5, and 6 were treated simultaneously with alcohol and minocycline (10, 20, 30 and 40 mg/kg I.P, respectively) for 21 days. Group 7 received minocycline alone (40 mg/kg, i.p) for 21 days. Morris water maze (MWM) has been used to assess cognitive activity. Hippocampal neurodegenerative and histological parameters as well as cyclic AMP response element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) levels were assessed. Alcohol impaired cognition, and concurrent therapy with various minocycline doses attenuated alcohol-induced cognition disturbances. Additionally, alcohol administration boosted lipid peroxidation and levels of glutathione in oxidized form (GSSG), tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β), and Bax protein, while decreased reducing type of glutathione (GSH), Bcl-2 protein, phosphorylated CREB, and BDNF levels in rat hippocampus. Alcohol also decreased the activity in the hippocampus of superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione reductase (GR). In comparison, minocycline attenuated alcohol-induced neurodegeneration; elevating expression levels of P-CREB and BDNF and inhibited alcohol induced histopathological changes in both dentate gyrus (DG) and CA1 of hippocampus. Thus, minocycline is likely to provide neuroprotection against alcohol-induced neurodegeneration through mediation of the P-CREB/BDNF signaling pathway.

Diabetic complications and oxidative stress: The role of phenolic-rich extracts of saw palmetto and date palm seeds

Recently, we reported that the date palm seed (DP) and saw palmetto seed (SP) extracts possessed a great amount of phenolic contents with potent antioxidant, antimicrobial, and anti-inflammatory activities. Therefore, this study aimed to assess the role of DP and SP phenolic-rich extracts in modulating diabetic complications and oxidative stress in the STZ- diabetic rat. DP and SP extracts significantly inhibited both microbial and pancreatic α-amylases. The STZ-induced diabetic rat groups treated with DP and SP extracts exhibited reversed hyperglycemia (40% and 54%, p < .001-.01) and body weight (70%, p < .001) alteration close to normal. Moreover, DP and SP extracts modulated serious damages in the structures of the pancreas, kidney, and liver of diabetic rats. DP and SP extracts improved the decline of the activities of antioxidant enzymes: Catalase, glutathione-S-transferase, glutathione reductase, and glutathione peroxidase in liver, kidney, and pancreas of the diabetic rats. PRACTICAL APPLICATIONS: Generally, date seed is a rich source of dietary fibers, polyphenols, and antioxidants and used in foods and pharmaceuticals. Our study reported that date palm seed (DP) and saw palmetto seed (SP) phenolic-rich extracts attenuated diabetes and its complications, probably tissue regeneration and normalizing the oxidative stress in the STZ-induced diabetic rat.

Renoprotective effect of Capsicum annum against ethanol-induced oxidative stress and renal apoptosis

The present study explored the ameliorative potency of aqueous extract of Capsicum annum (AqCA), against oxidative imbalance and renal toxicity induced by ethanol. Randomly grouped male Wistar rats (n = 6), were marked as ethanol-treated (2 g/kg bw, i.p.), CA₁₂₅ (125 mg/kg bw, i.p.), CA₂₅₀ (250 mg/kg bw, i.p.), ethanol pre-treated with CA (similar doses), and control (0.5 ml normal saline, i.p.), and treated for 30 consecutive days. Biochemical analysis of tissue and serum parameters was performed, along with histopathological and histochemical studies. Also, we performed TUNEL assay and western blotting for our experimental groups. Statistical analysis revealed significant (p ≤ .001) alteration in the levels of antioxidant enzymes, serum urea, creatinine, pro-inflammatory cytokines, and cleaved caspases, along with histopathological alterations in the ethanol-treated group. Prior treatment with AqCA prevented ethanol-induced alterations in tissue and serum parameters. These findings indicate that the extract of CA can protect renal cells from ethanol-induced damage by inhibiting oxidative stress, inflammatory response, and apoptosis. PRACTICAL APPLICATIONS: Chronic alcohol consumption is a major public health concern that leads to various diseases and social problems as well. It affects both the affluent and non-affluent society equally. Alcohol (ethanol) is a renowned hepato-toxicant and a well-documented risk factor for oxidative stress, with less known effect on the kidney. Thus, it is essential to investigate the effect of alcohol metabolism on the kidney to find a remedy to prevent it. The present investigation depicts the anti-oxidative and anti-inflammatory role of Capsicum annum against ethanol-induced renal damage. The outcome of this study can be utilized in the future for phytotherapeutic herbal drug formulation. Besides, the bioactive components identified in the study can be further explored by researchers or pharmaceutical corporates for potential therapeutic purpose against renal impairment.

Alcohol Consumption Can be a "Double-Edged Sword" for Chronic Kidney Disease Patients

Excessive drinking of alcohol is becoming a worldwide problem, and people have recognized that there exists a close relationship between chronic kidney disease (CKD) and alcohol consumption. However, there are many inconsistencies between experimental and clinical studies on alcohol consumption and kidney damage. The possible reason for this contradictory conclusion is the complex drinking pattern of humans and some bioactivators in wine. In addition, the design itself of the clinical studies can also produce conflicting interpretations of the results. Considering the benefits of light-to-moderate alcohol consumption, we recommend that CKD patients continue light-to-moderate drinking, which is beneficial to them. Because alcohol consumption can lead to adverse events, we do not advise non-drinkers to start to drink. Although light-to-moderate alcohol consumption may not pose a risk to patients with CKD, the patients’ condition needs to be considered. Consumption of even small amounts of alcohol can be associated with increased death risk. Additional clinical and experimental studies are needed to clarify the effect of alcohol on the kidneys and alcohol consumption on CKD patients.

Bio-accessible milk casein derived tripeptide (LLY) mediates overlapping anti- inflammatory and anti-oxidative effects under cellular (Caco-2) and in vivo milieu

Inflammation and oxidative stress are closely linked patho-physiological processes which occur concurrently in many diseased conditions. Recently, interdependence between these two processes explains the antioxidant paradox associated with failure to select appropriate agents required for prevention of diseases known to be induced by oxidative stress. Present study established the overlapping anti-inflammatory and anti-oxidative potential along with bio-accessibility of milk casein derived tripeptide (LLY). Tripeptide exhibited anti-inflammatory response under ex vivo conditions by suppressing (P<.01) mice splenocytes proliferation and modulating their cytokines (IFN-γ, IL-10 and TGF-β) with improved phagocytosis of peritoneal macrophages. Conversely, tripeptide displayed extraordinary radical scavenging ability and cellular anti-oxidative potential using chemical assays and H₂O₂ induced oxidative stress model on Caco-2 cells. Under cellular assessment, on one hand tripeptide inhibited (P<.01) intracellular ROS generation and reduced MDA and protein carbonyls but on the other also increased (P<.01) the activity of anti-oxidative enzyme, catalase without much effect on SOD and GPx. This anti-oxidative potential was further established by studying relative expression of genes (Nrf-2 and Keap1) and Nrf-2 nuclear translocation associated with anti-oxidative signaling in Caco-2 cells. Bio-accessibility of tripeptide and its intact transport across Caco-2 cell monolayer was also found to be 1.72±0.22% through PepT1 mediated transport mechanism. Besides, tripeptide displayed strong anti-oxidative and anti-inflammatory potential under in vivo conditions in mice against ethanol induced oxidative stress by elevating (P<.01) liver GSH content and by decreasing (P<.01) the activities of anti-oxidative enzymes, MDA along with reduced expression of CYP2E1, PPAR-α, TNF-α and COX-2 genes than ethanol control.

Alcoholic Beverage Consumption and Chronic Diseases

Epidemiological and experimental studies have consistently linked alcoholic beverage consumption with the development of several chronic disorders, such as cancer, cardiovascular diseases, diabetes mellitus and obesity. The impact of drinking is usually dose-dependent, and light to moderate drinking tends to lower risks of certain diseases, while heavy drinking tends to increase the risks. Besides, other factors such as drinking frequency, genetic susceptibility, smoking, diet, and hormone status can modify the association. The amount of ethanol in alcoholic beverages is the determining factor in most cases, and beverage types could also make an influence. This review summarizes recent studies on alcoholic beverage consumption and several chronic diseases, trying to assess the effects of different drinking patterns, beverage types, interaction with other risk factors, and provide mechanistic explanations.

Hypoglycemic, hypolipidemic and antioxidant effects of pioglitazone, insulin and synbiotic in diabetic rats

AIM

The objective of the study was to assess the effect of combination treatment of insulin, pioglitazone and synbiotic on streptozotocin (STZ)-induced diabetic rats.

MATERIALS AND METHODS

Diabetes mellitus was induced chemically by intraperitoneal administration of STZ (40 mg/kg b.wt) to male Sprague-Dawley rats. The rats were divided randomly into six groups of six rats in each. Group 1 was maintained as a normal control. Group 2 was maintained as diabetic control; Group 3 was treated with insulin; Group 4 with insulin + synbiotic; Group 5 with insulin + pioglitazone; and Group 6 with insulin + synbiotic + pioglitazone. All the animals were treated for 60 days.

RESULTS

Body weights, and concentration of reduced glutathione (GSH), and high-density lipoproteins cholesterol were significantly (p<0.05) reduced, whereas the concentration of blood glucose, total cholesterol, triglycerides, protein carbonyls and thiobarbituric acid reacting substances, and the activity of GSH peroxidase were significantly (p<0.05) elevated in Group 2 at the end of 8(th) week as compared to Group 1. The treatment Groups 3, 4, 5 and 6 revealed improvement in all the parameters, and the highest improvement was observed in combination Group 6.

CONCLUSION

From this study, it is concluded that combination of insulin, pioglitazone and synbiotic is useful in treating diabetes.

The Role of Oxidative Stress and Antioxidants in Liver Diseases

A complex antioxidant system has been developed in mammals to relieve oxidative stress. However, excessive reactive species derived from oxygen and nitrogen may still lead to oxidative damage to tissue and organs. Oxidative stress has been considered as a conjoint pathological mechanism, and it contributes to initiation and progression of liver injury. A lot of risk factors, including alcohol, drugs, environmental pollutants and irradiation, may induce oxidative stress in liver, which in turn results in severe liver diseases, such as alcoholic liver disease and non-alcoholic steatohepatitis. Application of antioxidants signifies a rational curative strategy to prevent and cure liver diseases involving oxidative stress. Although conclusions drawn from clinical studies remain uncertain, animal studies have revealed the promising in vivo therapeutic effect of antioxidants on liver diseases. Natural antioxidants contained in edible or medicinal plants often possess strong antioxidant and free radical scavenging abilities as well as anti-inflammatory action, which are also supposed to be the basis of other bioactivities and health benefits. In this review, PubMed was extensively searched for literature research. The keywords for searching oxidative stress were free radicals, reactive oxygen, nitrogen species, anti-oxidative therapy, Chinese medicines, natural products, antioxidants and liver diseases. The literature, including ours, with studies on oxidative stress and anti-oxidative therapy in liver diseases were the focus. Various factors that cause oxidative stress in liver and effects of antioxidants in the prevention and treatment of liver diseases were summarized, questioned, and discussed.

Mangiferin from Salacia chinensis prevents oxidative stress and protects pancreatic β-cells in streptozotocin-induced diabetic rats

Oxidative stress in diabetic tissues is a consequence of free radical accumulation with concurrently impaired natural antioxidants status and results in oxidative tissue damage. The present study investigated the protective effects of mangiferin against pancreatic β-cell damage and on the antioxidant defense systems in streptozotocin (STZ)-induced diabetic rats. Diabetes was experimentally induced by a single intraperitoneal injection of STZ. Oxidative stress biomarkers such as tissue malondialdehyde, hydroperoxides, reduced glutathione (GSH) content, and nonenzymatic antioxidants were measured. Biochemical observations were further substantiated with histological examination and ultrastructural studies in the pancreas of diabetic, glibenclamide and mangiferin-treated diabetic rats (dosage of 40 mg/kg body weight daily for 30 days). Oral administration of mangiferin and glibenclamide to diabetic rats significantly decreased the level of blood glucose and increased levels of insulin. Additionally, mangiferin treatment significantly modulated the pancreatic nonenzymatic antioxidants status (vitamin C, vitamin E, ceruloplasmin, and reduced GSH content) and other oxidative stress biomarkers. The histoarchitecture of diabetic rats showed degenerated pancreas with lower β-cell counts, but mangiferin treatment effectively regenerated insulin secreting islet cells. The electron microscopic study revealed damaged nuclear envelope and mitochondria and fewer secretory granules in pancreas of diabetic rats; however, mangiferin treatment nearly normalized pancreatic architecture. The present findings suggest that mangiferin treatment exerts a therapeutic protective nature in diabetes by decreasing oxidative stress and protecting against pancreatic β-cell damage, which may be attributable to its antioxidative properties.

Chronic alcohol consumption, type 2 diabetes mellitus, insulin-like growth factor-I (IGF-I), and growth hormone (GH) in ethanol-treated diabetic rats

AIMS

Alcohol has deleterious influences on glucose metabolism which may contribute to the development of type 2 diabetes mellitus (T2DM). Insulin-like growth factor I (IGF-I) and growth hormone (GH), which interact with insulin to modulate metabolic control, have been shown to be related to impaired glucose tolerance. This study was conducted to assess the possibility that altered circulating IGF-I and GH levels contribute to the exacerbation of T2DM by alcohol use in type 2 diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats and non-diabetic Long-Evans Tokushima Otsuka (LETO) rats.

MAIN METHOD

OLETF rats were pair-fed a Lieber-DeCarli Regular Ethanol diet and LETO rats were pair-fed a control diet for 6 weeks. At 6 weeks, an Intraperitoneal Glucose Tolerance Test (IP-GTT) was performed and IGF-I and GH levels were evaluated.

KEY FINDINGS

Prior to an IP-GTT, OLETF-Ethanol (O-E) group had significantly a decrease in the mean glucose levels compared to OLETF-Control (O-C) group. At 120 min post IP-GTT, the O-E group had significantly an increase in the mean glucose levels compared to O-C group. The serum IGF-I levels were significantly lower and the serum GH levels were significantly higher in the O-E group than in L-C group.

SIGNIFICANCE

These results suggest that IGF-I and GH are prominent in defining the risk and development of T2DM, and may be adversely affected by heavy alcohol use, possibly mediating its diabetogenic effects. Thus, the overall glucose intolerance in the setting of alcoholism may be attributable to inappropriate alteration of IGF-I and GH levels.