Effects of melatonin on streptozotocin-induced diabetic liver injury in rats

Hepatoprotective potential of alpha-lipoic acid against gliclazide-induced liver injury in high-glucose-exposed human liver cells and experimental type 2 diabetic rats

Growing clinical evidence shows that sulfonylurea therapy for patients with type 2 diabetic mellitus (T2DM) contributes to progressive worsening of their liver. The present study presents hepatotoxicity induced by gliclazide, a second-generation sulfonylurea, and alpha-lipoic acid (ALA) as a novel and promising drug for T2DM treatment. Normal human liver cells (HL-7702) were incubated with high-glucose DMEM in the presence or absence of gliclazide and ALA for 72 h, and cell viability and death were measured by flow cytometry. Next, Sprague-Dawley rats were subjected to 12 h of fasting, and fasting blood glucose was measured. The rats were randomized into four groups: HC (healthy control; n = 7), T2DM (diabetic rats without treatment; n = 9), GLC (diabetic rats with 15 mg/kg gliclazide treatment; n = 7) and GLC+ALA (diabetic rats with gliclazide and 60 mg/kg ALA treatment; n = 7). T2DM was induced by a bolus administration of 110 mg/kg nicotinamide and 55 mg/kg streptozotocin intraperitoneally. The experimental protocol lasted for 6 weeks after which the animals were sacrificed and pancreas, liver and blood samples were collected for biochemical, histological and molecular analyses. Compared to healthy control (HC) group, exposure of HL-7702 cells to high glucose induced significant cell death by 19 % (p < 0.001), which was exacerbated with gliclazide treatment by 29 % (p < 0.0001) but markedly reduced by 6 % to near HC value following ALA treatment. In vivo, GLC-treated rats had severe liver damage characterized by increased hepatocellular vacuolation, and significant expression of ED-1, iNOS and caspase-3 as well as markedly high levels of liver enzymes (aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase compared to T2DM rats. Interestingly, ALA administration prevented these pathological changes and protected the diabetic liver to levels comparable to HC rats. ALA showed hepatoprotective effect against gliclazide-induced hepatotoxicity by suppressing inflammation and apoptosis while activating antioxidant pathway in the diabetic liver. Abbreviations: ALA, Alpha-lipoic acid; ALT, Alanine aminotransferase; ALP, Alkaline phosphatase; AMPK, Adenosine monophosphate-activated protein kinase; AST, Aspartate aminotransferase; ATP, Adenosine triphosphate; DMEM, Dulbecco's Modified Eagle Medium; EDTA, ethylenediaminetetraacetic acid; FBG, Fasting blood glucose; FBS, Fetal bovine serum; GLC, Gliclazide; GLUT4, Glucose transporter type 4; GSH, Glutathione; H&E, Hematoxylin/Eosin; HbA1c, Glycosylated haemoglobin A1c; HC, Healthy control; HG, Hyperglycemic group; HOMA-β, Homeostasis model assessment of β-cell function; IL-1β, Interleukin-1β; IL-6, Interleukin-6; iNOS, Inducible nitric oxide synthase; KATP, ATP-dependent potassium channels; MDA, Malondialdehyde; MPTP, Mitochondrial permeability transition pore; NO, Nitric oxide; P/S, Penicillin/streptomycin; PAS, Periodic acid-Schiff; RIA, Radioimmunoassay; ROS, Reactive oxygen species; SOD, Superoxide dismutase; T2DM, Type 2 diabetes mellitus; TBARS, Thiobarbituric acid reactive substances; TNF-α, Tumor necrosis factor-alpha.

Melatonin increases AKT and SOD gene and protein expressions in diabetic rats

Diabetes mellitus (DM) is a chronic metabolic disease marked by hyperglycemia due to insulin deficiency or insulin resistance leading to many chronic complications. It is thus important to manage diabetes effectively in order to prevent and or delay these complications. Melatonin is produced by the pineal gland and regulates the wake-sleep circadian rhythm. Existing evidence suggests that melatonin may be effective in the management of DM. However, the evidence on the mechanism of the beneficial effect melatonin as a treatment for DM is limited. In this study, we investigated the effect of melatonin treatment on blood glucose, insulin (INS), AKT and superoxide dismutase (SOD) gene levels in diabetic rats. Non-diabetic and diabetic rats were treated orally for 4 weeks with either 25 mg or 50 mg/kg body weight of melatonin. At the end of the study, pancreatic and liver tissues morphology, glucose homeostasis, serum insulin and SOD levels, hepatic gene and protein expression of SOD as protecting antioxidant enzyme and AKT as central element involved in PI3K/AKT insulin signaling pathway were estimated. Melatonin treated diabetic rats showed reduced hyperglycemia, and increased serum insulin and SOD levels. In addition, melatonin induced an increased gene and protein expression of SOD and AKT. In conclusion, melatonin may play a role in treating diabetic rats via stimulation of insulin secretion, insulin signaling and reduction in oxidative stress.

Antidiabetic effects of polyherbal mixture made of Centaurium erythraea, Cichorium intybus and Potentilla erecta

ETHNOPHARMACOLOGICAL RELEVANCE

The polyherbal mixture made of Centaurium erythraea aerial parts and Cichorium intybus roots and Potentilla erecta rhizomes has been used for centuries to treat both the primary and secondary complications of diabetes.

AIM OF THE STUDY

As a continuation of our search for the most effective herbal mixture used as an ethnopharmacological remedy for diabetes, this study aimed to compare the in vitro biological activities of this polyherbal mixture and its individual ingredients, and, most importantly, to validate the ethnopharmacological value of the herbal mixture through evaluation of its phytochemical composition, its potential in vivo toxicity and its effect on diabetes complications.

MATERIALS AND METHODS

Phytochemical analysis was performed using HPLC-UV. Antioxidant activity was estimated via the DPPH test. Potential cytotoxicity/anticytotoxicity was assessed using an in vitro RBCs antihemolytic assay and an in vivo sub-chronic oral toxicity method. Antidiabetic activity was evaluated using an in vitro α-amylase inhibition assay and in vivo using a chemically induced diabetic rat model.

RESULTS

The HPLC-UV analysis revealed the presence of p-hydroxybenzoic acid, p-hydroxybenzoic acid derivative, catechin, five catechin derivatives, epicatechin, isoquercetin, hyperoside, rutin, four quercetin derivatives, caffeic acid, and four caffeic acid derivatives in the polyherbal mixture decoction. Treatment with the decoction has shown no toxic effects. The antioxidant and cytoprotective activities of the polyherbal mixture were higher than the reference's ones. Its antidiabetic activity was high in both in vitro and in vivo studies. Fourteen days of treatment with the decoction (15 g/kg) completely normalized blood glucose levels of diabetic animals, while treatments with insulin and glimepiride only slightly lowered glycemic values. In addition, lipid status of treated animals as well as levels of serum AST, ALT, ALP, creatinine, urea and MDA were completely normalized. In addition, the polyherbal mixture completely restored the histopathological changes of the liver, kidneys and all four Cornu ammonis regions of the hippocampus.

CONCLUSIONS

The polyherbal mixture was effective in the prevention of both primary and secondary diabetic complications such as hyperlipidemia, increased lipid peroxidation, non-alcoholic fatty liver disease, nephropathy and neurodegeneration.

Okra [Abelmoschus esculentus (L.) Moench] improved blood glucose and restored histopathological alterations in splenic tissues in a rat model with streptozotocin-induced type 1 diabetes through CD8+ T cells and NF-kβ expression

Diabetes mellitus is a complex metabolic syndrome that involves dysfunction of spleen and other lymphoid organs. Medicinal plants, including okra (Abelmoschus esculentus (L.) Moench), were used widely for diabetes treatment. Scarce data are available about the potential anti-diabetic effects of okra, the histopathological alterations in splenic tissues and the mechanistic pathways underlying this association. The current research investigated the effects of okra pod extract on the biochemical parameters and expression of CD8+ T cells and nuclear factor kappa (NF-k) B and releasing proinflammatory cytokines in spleen in streptozotocin (STZ)-induced diabetic rat models. A total of 50 mature male Wister albino rats were divided into five isolated groups; the first served as control (untreated) animals, the second (DM group) diabetes induced by STZ (at a dose of 45 mg/kg body weight, administered intraperitoneally), the third group (DM + Insulin): diabetic rats administered insulin subcutaneously (10 units/kg bw/day) daily for 4 weeks, the fourth group was administrated 400 mg/kg okra extract daily for 4 weeks, and diabetic induced rats in the fifth group were administrated 400 mg/kg okra extract daily for 4 weeks. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity in Abelmoschus esculentus (L.) Moench was studied, and the content of phenolic compounds in okra pods was estimated using high-performance liquid chromatography. Diabetes induction led to decreased body weight, increased blood glucose levels. Capsular thickness was significantly increased, white pulp was widely dispersed, and mature lymphocytes in the periphery were also drastically decreased, with thick follicular arteries, necrosis, and depletion of lymphocytes in the germinal center. Red pulp revealed severe congestion and degenerative changes, deposition of hemosiderin granules and lymphocytic depletion. In addition, collagen fiber deposition was increased also in this group. The induction of diabetes exaggerated NF-kβ expression and mediated downregulation of the expression of CD8+ T cells in spleen tissue. Interestingly, oral administration of okra extracts post diabetes induction could mitigate and reverse such adverse effects. Altogether, our study points out the potential benefits of okra in improving blood glucose levels and restoring histopathological alterations in splenic tissues through CD8+ T cells and NF-kβ expression in a diabetic rat model.

Therapeutic treatments for diabetes mellitus-induced liver injury by regulating oxidative stress and inflammation

Diabetes mellitus (DM) is a metabolic disease that affects all systems in the body, including the liver. Numerous studies have reported that chronic DM etiology and pathogenesis complications implicate oxidative stress, generating reactive oxygen species, such as superoxide anions and free radicals. In addition, pro-inflammatory reactions are also underlying functions closely related to oxidative stress that further exacerbate pathological DM states. The liver is especially susceptible to hyperglycemia-induced oxidative stress and the related inflammation. Thus, anti-oxidation and anti-inflammation therapies are promising strategies for treating liver damage. This review summarizes therapeutic treatments attenuating the generation of oxidative stress and pro-inflammation, which also cause DM-induced liver injury. Although the treatments have several impediments to be solved, these remedies may have clinically important implications under the absence of effective drugs for the damaged liver in DM patients.

The effects of camelina sativa oil and high-intensity interval training on liver function and metabolic outcomes in male type 2 diabetic rats

Objectives

The purpose of this study was to evaluate the independent and combined effects of camelina sativa oil and high-intensity interval training (HIIT) on liver function, and metabolic outcomes in streptozotocin-induced diabetic rats.

Methods

Forty male Wistar rats were randomly assigned to five equal groups (8 per group): Normal control (NC), diabetic control (DC), diabetic + camelina sativa oil (300 mg/kg by oral gavage per day; D + CSO), diabetic + HIIT (running on a treadmill 5 days/week for 8 weeks; D + HIIT), diabetic + camelina sativa oil + HIIT (D + CSO +  HIIT).

Results

In all three intervention groups (D + CSO, D + HIIT, and D + CSO + HIIT) compared to the DC, hepatic TNF-α, MDA, and histopathology markers, decreased and hepatic PGC-1α, and PPAR-γ increased (p < 0.05). However, the effect of D + CSO was greater than D + HIIT alone. Hepatic TG decreased significantly in D + HIIT and D + CSO + HIIT compared to other groups (p < 0.001). Fasting plasma glucose in all three intervention groups (D + CSO, D + HIIT, and D + CSO + HIIT) and HOMA-IR in D + CSO and D + CSO + HIIT were decreased compared to DC (p < 0.001). Only hepatic TAC and fasting plasma insulin remained unaffected in the three diabetic groups (p < 0.001). Overall, D + CSO + HIIT had the largest effect on all outcomes.

Conclusions

At the doses and treatment duration used in the current study, combination of CSO and HIIT was beneficial for reducing liver function and metabolic outcomes other than CSO and HIIT alone.

Oxidative stress in liver of streptozotocin-induced diabetic mice fed a high-fat diet: A treatment role of Artemisia annua L

Objective. The aim of this study was the investigation of a treatment role of Artemisia annua L. (AA) on liver dysfunction and oxidative stress in high-fat diet/streptozotocin-induced diabetic (HFD/STZ) mice. Methods. Sixty mice were divided into 12 groups including control, untreated diabetic, and treated diabetic ones with metformin (250 mg/kg), and doses of 100, 200, and 400 mg/kg of water (hot and cold) and alcoholic (methanol) extracts of AA. Type 2 diabetes mellitus (T2DM) was induced in mice by high-fat diet for 8 weeks and STZ injection in experimental animals. After treatment with doses of 100, 200 or 400 mg/kg of AA extracts in HFD/STZ diabetic mice for 4 weeks, oxidative stress markers such as malondialdehyde (MDA), glutathione (GSH), and free radicals (ROS) were determined in the liver tissue in all groups. Results. Diabetic mice treated with metformin and AA extracts showed a significant decrease in ROS and MDA concentrations and a notable increase in GSH level in the liver. Effectiveness of higher doses of AA extracts (200 and 400 mg/kg), especially in hot-water and alcoholic ones, were similar to and/or even more effective than metformin. Conclusion. Therapeutic effects of AA on liver dysfunction showed that antioxidant activity of hot-water and alcoholic AA extracts were similar or higher than of metformin.

Evaluation of Pleurotus Mushroom Effects on Histopathological Changes in Organs of Diabetic Rats

Diabetes mellitus (DM) is a metabolic disorder that can be categorized mainly into type 1 and type 2. Diabetes type 1 is caused due to β-cell destruction, whereas type 2 is caused by the resistance of cell receptors. Many therapies are available for the management of diabetes, but they have some side effects, and as a result of this, people are attracted to natural treatments. Pleurotus mushrooms are well documented for their medicinal attributes and their role in the treatment of diseases like cancer, infectious disease, neurodiseases, and inflammatory disease. The protective mechanism of the Pleurotus fossulatus (P. fossulatus) mushroom and its detailed histological study on kidneys and the liver in diabetic conditions were unexplored. The present study evaluated the effects of P. fossulatus aqueous extract on histological changes in the diabetic rat model. Male Wistar albino rats were used to create the diabetic model by using streptozotocin (STZ) intraperitoneal (IP) injection. The animals were separated into five different groups, with six animals in each. Only group I, animals that did not receive STZ, was considered a normal control. Group II was a diabetic control and received normal saline, and group III was a drug control and received metformin as a standard drug. Groups IV and V were dosing groups, which received the aqueous extract of P. fossulatus in 250 mg/kg and 500 mg/kg of body weight concentrations, labeled as T1 and T2 groups, respectively. The T1 and T2 groups clearly showed their potential to reverse the histopathological changes in the kidney and liver. However, the T2 group was more effective than the T1 group, as results indicate that functions of the glomerulus and its structural deformity were restored to their near-natural form in the T2 group. In the case of the liver, the histological changes like the dilatation of sinusoids, more numbers of the Kupffer cell formation, and necrosis were restored in the T2 group. All these results proved the potential of P. fossulatus against the side effects of diabetes. It could protect the organs from developing diabetic nephropathy (DN) and liver-related diseases like cirrhosis and nonalcoholic fatty liver disease (NAFLD).

Hibiscus sabdariffa L. polyphenolic-rich extract promotes muscle glucose uptake and inhibits intestinal glucose absorption with concomitant amelioration of Fe2+ -induced hepatic oxidative injury

In this current study, the antidiabetic effectiveness of Hibiscus sabdariffa and its protective function against Fe²⁺ -induced oxidative hepatic injury were elucidated using in vitro, in silico, and ex vivo studies. The oxidative damage was induced in hepatic tissue by incubation with 0.1 mMolar ferrous sulfate (FeSO4) and then treated with different concentrations of crude extracts (ethyl acetate, ethanol, and aqueous) of H. sabdariffa flowers for 30 min at 37°C. When compared to ethyl acetate and aqueous extracts, the ethanolic extract displayed the most potent scavenging activity in ferric-reducing antioxidant power (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and nitric oxide (NO) assays, with IC₅₀ values of 2.8 μl/ml, 3.3 μl/ml, and 9.2 μl/ml, respectively. The extracts significantly suppressed α-glucosidase and α-amylase activities (p < .05), with the ethanolic extract demonstrating the highest activity. H. sabdariffa significantly (p < .05) raised reduced glutathione (GSH) levels while simultaneously decreasing malondihaldehyde (MDA) and NO levels and increasing superoxide dismutase (SOD) and catalase activity in Fe²⁺ induced oxidative hepatic injury. The extract of the plant inhibited intestinal glucose absorption and increased muscular glucose uptake. The extract revealed the presence of several phenolic compounds when submitted to gas chromatography-mass Spectroscopy (GC-MS) screening, which was docked with α-glucosidase and α- amylase. The molecular docking displayed the compound 4-(3,5-Di-tert-butyl-4-hydroxyphenyl)butyl acrylate strongly interacted with α-glucosidase and α-amylase and had the lowest free binding energy compared to other compounds and acarbose. These results suggest that H. sabdariffa has promising antioxidant and antidiabetic activity. PRACTICAL APPLICATIONS: In recent years, there has been increased concern about the side effects of synthetic anti-diabetic drugs, as well as their expensive cost, especially in impoverished nations. This has instigated a radical shift towards the use of traditional plants, which are rich in phytochemicals many years ago. Among these plants, H. sabdariffa has been used to treat diabetes in traditional medicine. In this present study, H. sabdariffa extracts demonstrated the ability to inhibit carbohydrate digesting enzymes, facilitate muscle glucose uptake and attenuate oxidative stress in oxidative hepatic injury. Hence, demonstrating H. sabdariffa's potential to protect against oxidative damage and the complications associated with diabetes. Consumption of Hibiscus tea or juice may be a potential source for developing an anti-diabetic drug.

Melatonin ameliorates the adrenal and pancreatic alterations in streptozotocin-induced diabetic rats: Clinical, biochemical, and descriptive histopathological studies

Previous studies have demonstrated the beneficial effects of melatonin in diabetic rats. However, limited studies have been conducted on the potential effects of melatonin on the descriptive histopathological and morphometric findings in different compartments of the adrenal glands in diabetic animal models. In this study, using a streptozotocin (STZ)-induced diabetic rat model, we sought to examine histological alterations in the pancreas and adrenal glands and observe the effect of the administration of melatonin on the histopathology and morphology of the pancreas and the adrenal gland cortex and medulla that are altered by STZ-induced hyperglycemia. Rats were randomly assigned to four different groups: Group I, normal control; Group II, melatonin group (MT) (10 mg/kg/day); Group III, (diabetic STZ group), and Group IV, diabetic (STZ) + melatonin group (MT). Throughout the experiment, the animals' fasting blood sugar levels were measured. Blood was obtained to determine the animals' cumulative blood sugar levels after sacrification. For histological and morphometrical evaluations, the pancreatic and adrenal gland tissues were dissected and processed. Our results showed that diabetic rats receiving melatonin significantly (P < 0.05) improved their fasting blood sugar and cumulative blood sugar levels compared to the diabetic group not receiving melatonin. Furthermore, histopathological examinations of the pancreatic and adrenal tissues of the diabetic rats indicated the occurrence of severe histopathological and morphometric changes. Morphometric analysis of the adrenals indicated a significant increase (P < 0.05) in the thickness of the cortex zones [zona glomerulosa (ZG), zona fasciculata (ZF), and zona reticularis (ZR)] for the diabetic STZ group compared with other groups, and a significant decrease (P < 0.05) in the diameter of the in adrenal gland medullas in the diabetic STZ rats compared to the other groups. Furthermore, treatment with melatonin restored these changes in both the pancreatic and adrenal gland tissues and produced a significant (P < 0.05) improvement in the cortex and medulla thickness compared to the untreated diabetic rats. Overall, melatonin significantly reduced the hyperglycemic levels of glucose in diabetic rats and reversed the majority of histopathological alterations in the tissues of the pancreas and adrenals, demonstrating its anti-diabetic activity.

The effect of probiotics/synbiotics supplementation on renal and liver biomarkers in patients with type 2 diabetes: a systematic review and meta-analysis of randomised controlled trials

Despite the apparent beneficial effects of probiotics/synbiotics on glucose haemostasis, lipid profile and inflammatory responses, it is not clear whether these beneficial effects also impact renal and hepatic function in diabetes. Therefore, we sought to assess the effect of probiotics/synbiotics supplementation on renal and liver biomarkers in adults with type 2 diabetes mellitus (T2DM) using a systematic review and meta-analysis of randomised controlled trials (RCT). PubMed, Scopus, Web of Science and Cochrane Library were systematically searched, up to February 2021. The pooled weighted mean difference (WMD) was estimated using a random-effects model. The methodological quality of studies, as well as certainty of evidence, was assessed using standard scales. Fifteen related trials were identified. Meta-analysis of six trials, involving 426 participants, indicated that probiotics/synbiotics supplementation reduced serum levels of creatinine (WMD = -0·10 mg/dl, 95 % CI -0·20, -0·00; P = 0·01; I ² = 87·7 %; P-heterogeneity < 0·001), without any significant effect on blood urea nitrogen (BUN), glomerular filtration rate or microalbuminuria. No significant improvement was found on liver biomarkers following probiotics/synbiotics supplementation. The subgroup analysis showed a significant improvement in BUN when follow-up duration lasted for 12 weeks or more (WMD = -1·215 mg/dl, 95 % CI -1·933, -0·496; P = 0·001) and in creatinine levels in patients with renal dysfunction (WMD = -0·209 mg/dl, 95 % CI -0·322, -0·096; P < 0·001). Our results are insufficient to advocate the use of probiotics/synbiotics for improving renal or liver function in patients with T2DM. Indeed, due to the low certainty of evidence, these findings need to be affirmed in further high-quality RCT.

Alterations of Liver Functions and Morphology in a Rat Model of Prediabetes After a Short-term Treatment of a High-fat High-glucose and Low-dose Streptozotocin

BACKGROUND: The administration of high-fat and high-glucose in diet followed by a low-dose streptozotocin injection in rats could mimic hyperglycemia, prediabetic, or diabetic conditions in humans. However, whether the rat model may lead to early liver impairment was still unclear. AIM: This study was aimed to investigate the possible changes in liver functions and morphology in the rat model of prediabetes after a short-term administration of a high-fat and high-glucose diet followed by low-dose streptozotocin injection. METHODS: Eighteen male Wistar rats were divided into nine rats in the control group and nine in the prediabetic group. To induce prediabetic rats, high-fat high-glucose in daily diets for 3 weeks continued with once to twice low-dose streptozotocin was given. Rats in control groups were fed with a standard diet for 2 months. Afterward, we analyzed glucose control parameters, liver functions, and liver histology of the rats. RESULTS: High-fat, high-glucose diet combined with a low dose of streptozotocin successfully caused prediabetics in the rats. There was a significant increase in several liver enzymes, including aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyl transferase (GGT). However, no significant changes were found in the serum lactate dehydrogenase (LDH) and alkaline phosphatase (ALP) levels. The histological changes in the liver confirmed the increase in liver enzymes. CONCLUSION: Short-term administration of high-fat high-glucose in combination with low-dose streptozotocin triggers alterations in liver functions marker and liver morphology.

Ameliorative Effect of Annona muricata (Graviola) Extract on Hyperglycemia Induced Hepatic Damage in Type 2 Diabetic Mice

Annona muricata (AM) is evergreen plant of the Annonaceae family and known to have anticancer and antidiabetic effects. However, anti-diabetic mechanisms of AM extracts (AME) associated with hepatic glucose regulation and lipid metabolism remain unclear. In this study, we investigated the protective effect of AME extracted on hepatic damage in diabetic mice. Diabetes was induced by a high-fat diet with two-times streptozotocin (STZ) injection (60 mg/kg BW) in C57BL/6 male mice. The diabetic mice were daily administered with AME (50 or 100 mg/kg BW) by gavage for 9 weeks. Biomarkers related to energy metabolism and insulin signaling were examined to identify the effect of AME on hyperglycemia induced hepatic damage. AME supplementation reduced levels of FBG, HbA1c, HOMA-IR and hepatic lipid profiles as well as enhanced insulin signaling by increased the protein levels of IRS-1 accompanied GLUT2 in diabetic mice. Especially low dose of AME showed the beneficial effect of reducing oxidative stress (4-HNE, protein carbonyls, Nrf2, NQO1) and improved hepatic morphology demonstrated by lipid droplets along with upregulation of lipophagy (pAMPK, p-mTOR/mTOR, LC3-2/LC3-1) in diabetic mice. Moreover, AME supplementation ameliorated hepatic lipid metabolism (FAS, SREBP1c, C/EBPα, PPARγ, CPT1A, PPARα) and energy metabolism (pAMPK, PGC1α) in diabetic mice. Taken together, this study suggested that AME could be helpful to prevent hepatic abnormality by regulation of insulin signaling associated with energy metabolism and autophagy in diabetes.

Saccharomyces boulardii modulates oxidative stress and renin angiotensin system attenuating diabetes-induced liver injury in mice

Type 1 diabetes (T1DM) is a chronic disease characterized by hyperglycemia due to a deficiency in endogenous insulin production, resulting from pancreatic beta cell death. Persistent hyperglycemia leads to enhanced oxidative stress and liver injury. Several studies have evaluated the anti-diabetic and protective effects of probiotic strains in animal models. In the present study, we investigated, through histopathological and biochemical analyses, the effects of eight weeks of administration of Saccharomyces boulardii (S. boulardii) yeast on the liver of streptozotocin (STZ) induced diabetic C57BL/6 mice. Our results demonstrated that S. boulardii attenuates hepatocytes hydropic degeneration and hepatic vessels congestion in STZ-induced diabetic mice. The treatment attenuated the oxidative stress in diabetic mice leading to a reduction of carbonylated protein concentration and increased activity of antioxidant enzymes superoxide dismutase and glutathione peroxidase, compared to untreated diabetic animals. The results also show the beneficial influence of S. boulardii in regulating the hepatic concentration of renin angiotensin system (RAS) peptides. Therefore, our results demonstrated that S. boulardii administration to STZ-induced diabetic mice reduces oxidative stress and normalizes the concentration of RAS peptides, supporting the hypothesis that this yeast may have a role as a potential adjunctive therapy to attenuate diabetes-induced liver injury.

The hepatoprotective effects of fennel seeds extract and trans-Anethole in streptozotocin-induced liver injury in rats

Hypoglycemic, anti-inflammatory, and antioxidant activities of fennel have been recorded in numerous investigations. The study aimed to evaluate the protective effects of fennel or its active component trans-Anethole (TA) on streptozotocin-induced liver injury in rats. Rats were injected with a single dose of STZ (65 mg/kg) and treated with fennel (200 and 400 mg/kg), TA (80 mg/kg), or metformin (300 mg/kg) for 35 days. Serum lipid profile and liver enzyme activity (aminotransferases), oxidative stress markers, and the degree of fibrosis in the liver tissue were assessed. Both fennel and TA decreased blood glucose levels, reduced liver enzyme activity, food, and water intake, and intensity of weight loss, reduced serum triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), and increased high-density lipoprotein cholesterol (HDL-c). Additionally, fennel and TA significantly reduced MDA concentration while increased CAT activity and thiol content and reduced the degree of injury and fibrosis in the liver of diabetic rats. Our results suggest that fennel seed extract and its active compound TA are able to protect the liver against diabetes-induced hepatic injury in rats, probably via hypoglycemic and antioxidant effects.

Effect of Curculigo pilosa supplemented diet on blood sugar, lipid metabolism, hepatic oxidative stress and carbohydrate metabolism enzymes in streptozotocin-induced diabetic rats

BACKGROUND

Diabetes mellitus (DM) has continued to raise concern globally and Curculigo pilosa (CP) is used for its treatment and management in folkloric medicine. In this study, the in vitro antioxidant abilities of CP and the effects of CP-supplemented diets on blood sugar, lipid metabolism, oxidative stress and key carbohydrate metabolizing enzymes in streptozotocin (STZ)-induced diabetic rats were investigated.

METHODS

Polyphenol contents (total phenolic and total flavonoid) and antioxidant ability of different extracts of CP were determined in vitro. Diabetes mellitus were stimulated in healthy rats by single intraperitoneal administration of 50 mg/kg streptozotocin and it was confirmed by elevated blood glucose level after 3 days. Thirty six rats were distributed into six groups of six rats each and diabetic rats were fed with 5 and 10% CP-supplemented diet for 21 days. Thereafter, the effects of the dietary regimen were evaluated on blood glucose, body weight, hepatic carbohydrate metabolizing enzymes, lipid profile, oxidative stress markers, serum markers of hepatic and renal damages and histopathology studies.

RESULTS

Different extracts of CP contained polyphenol contents and exhibited antioxidant properties in different models used. Diabetic rats showed elevated level of blood glucose and body weight loss. Treatment of diabetic rats with CP-supplemented diet significantly (p < 0.05) lowered the blood glucose and improved body weight loss. Also, the treatment with the CP-supplemented diet significantly (p < 0.05) enhanced the activities of hepatic glycolytic (hexokinase and glucose-6-dehydrogenase) and lowered the gluconeogenic (fructose 1, 6 biphosphatase and glucose-6-phosphatase) enzymes in diabetic rats. The lipid profile, oxidative stress markers and serum markers of hepatic and renal damages were significantly (p < 0.05) restored to near normalcy in the diabetic rats. Histopathological slides also showed improvements in pancreas and hepatic tissues of diabetic rats treated with CP-supplemented diet.

CONCLUSION

Data obtained in this study suggested that CP-supplemented diet could be used as dietary regimen in the management of DM.

Antioxidant status and hepato-protective role of Anchomanes difformis in streptozotocin-induced diabetes in male Wistar rats

Introduction: The liver is involved in the metabolism of xenobiotics and their metabolites and it is vulnerable to oxidative damage. Hyperglycaemia is highly implicated in the progression of diabetes mellitus, and adversely affects the liver. Though, conventional hypoglycaemic drugs may be effective in reducing blood glucose, they do not appear to be effective in attenuating the progression of diabetes and its complications.

Objective: This study evaluated the ameliorative effects of Anchomanes difformis on hyperglycaemia and hepatic injuries in type 2 diabetes.

Methods: Type 2 diabetes was induced in male Wistar rats with a single intraperitoneal injection of streptozotocin (40 mg/kg BW) after two weeks of fructose (10%) administration. Aqueous extract of A. difformis (200 and 400 mg/kg BW) and glibenclamide (5 mg/kg BW) were administered orally for six weeks. Blood glucose concentrations were measured. Serum levels of liver dysfunction markers (ALT, AST, and ALP), total cholesterol, triglycerides, HDL- and LDL-cholesterol were investigated. Total protein, albumin, and globulin were also assessed. Antioxidant parameters: ORAC, GSH, GSSG, SOD, CAT and FRAP were evaluated in the liver while ORAC, FRAP and lipid peroxidation were determined in the serum. Histological examination of the liver tissue was carried out.

Results: Treatment with aqueous extract of A. difformis significantly (p<0.05) reduced blood glucose and reversed steatosis in the diabetic-treated rats. The antioxidant status of diabetic-treated rats was significantly (p<0.05) improved. Serum levels of liver dysfunction markers were significantly (p<0.05) reduced in diabetic-treated rats.

Conclusion: The findings in this study revealed that 400 mg/kgBW Anchomanes difformis was more effective than 200 mg/kg BW in ameliorating diabetes-induced hepatopathy, however, both doses of Anchomanes difformis demonstrated more antidiabetic ability than glibenclamide. Anchomanes difformis may be a novel and potential therapeutic agent in the management of diabetes and resulted hepatic injuries.

Therapeutic Effects of 5,7-Dihydroxy-6-Oxoheptadecanoic Acid on Dysglycemia, Dyslipidemia, and Other Complications in Diabetic Rats

The current study aimed to investigate the therapeutic effects of 5,7-dihydroxy-6-oxoheptadecanoic acid (DHA) from Tiliacora triandra on rat models of type 2 diabetes mellitus (T2DM). T2DM was induced with a combination of high-fat diet/streptozotocin (HFD/STZ), and diabetic rats were treated with DHA (25 mg/kg) for 30 days. The body weight, fasting blood glucose (FBG), serum, and liver biochemical parameters, as well as histological evaluations of the liver and pancreas, were evaluated. Diabetic rats displayed a significant increase in FBG, serum lipid profiles (triglycerides, total cholesterol, and low-density lipoprotein cholesterol), liver function enzymes (aspartate transaminase, alkaline phosphatase, and alanine transaminase), creatinine, liver malondialdehyde (MDA), and myeloperoxidase (MPO) contents. Furthermore, insulin level and liver antioxidant enzyme activities (catalase [CAT], superoxide dismutase [SOD], and glutathione peroxidase [GSH-Px]) were significantly reduced in the diabetic rats. Whereas, treatment with DHA significantly reduced FBG, serum lipids, liver function enzymes, serum creatinine, liver MDA, and MPO contents. In addition, treatment with DHA significantly increased serum insulin level and liver SOD, CAT, and GSH-Px activities. In addition, DHA alleviated histopathological changes in the pancreas and liver caused by T2DM. These results portray the antidiabetic and antioxidative properties of DHA and can be considered as a potential treatment for T2DM.

Melatonin regulates the expression of inflammatory cytokines, VEGF and apoptosis in diabetic retinopathy in rats

The present study analyzed whether melatonin could mediate the expression of VEGF, IL-6 and TNF-α, as well as the apoptotic index in rats with diabetic retinopathy. Fifty Wistar albino rats were divided into the following groups: GC: rats without induction of diabetes by streptozotocin; GD: rats induced to diabetes by streptozotocin and treated with placebo; GDM: rats induced to diabetes by streptozotocin and after confirmation treated with melatonin at a dose of 10 mg/kg for 20 days; GDMS: rats induced to diabetes by streptozotocin and treated simultaneously with melatonin at a dosage of 10 mg/kg for 20 days; GDI: rats induced to diabetes by streptozotocin and after confirmation treated with insulin for 20 days. Diabetes was induced by intraperitoneal injections of streptozotocin (60 mg/kg), and insulin (5 U/day) was administered subcutaneously. For apoptosis TUNEL was used, while for the analysis of VEGF, IL-6 and TNF-α. The results showed that the groups that were treated with melatonin decreased the expression of cytokines and VEGF, in addition to apoptosis. Thus, it is concluded that melatonin can regulate the expression of these factors by improving the condition of the retina in diabetic retinopathy.

Hepatoprotective Effects of a Ruthenium(II) Schiff Base Complex in Rats with Diet-Induced Prediabetes

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Ruthenium(II) Schiff-base complex normalizes liver damage biomarker enzymes.

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Ruthenium(II) Schiff-base complex reduced hepatic lipid accumulation and restored liver and body weight.

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Ruthenium(II) Schiff-base complex decreased plasma SREBP-1c levels.

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Ruthenium(II) Schiff-base complex prevented hepatomegaly and prediabetes-related NAFLD progression.

Background

Progressive insulin resistance in a prediabetic state has been reported to be the predominant causative factor for the development of nonalcoholic fatty liver disease. The combination of dietary modification and pharmacotherapy has been recommended to manage diabetic liver complications. However, poor patient compliance and toxicity of current drug therapy on liver function still results; thus, newer alternative drugs are required.

Objective

This study sought to investigate the hepatoprotective effects of the ruthenium(II) Schiff base complex in the presence and absence of dietary intervention in a diet-induced pre-diabetic rat model.

Methods

Prediabetic rats were randomly allocated to respective treatment groups. The ruthenium-based compound (15 mg/kg) was administered to the prediabetic rats in both the presence and absence of dietary intervention once a day every third day for 12 weeks.

Results

The administration of the ruthenium compound in both the presence and absence of dietary intervention resulted in the restoration of liver and body weights. This treatment also reduced liver damage enzyme biomarkers, bilirubin, and sterol regulatory element binding protein 1c concentrations in the plasma.

Conclusions

The ruthenium(II) complex showed beneficial effects as it ameliorated and prevented the progression of diabetes-related liver derangements while eliminating the hepatotoxicity associated with the use of metal compounds. However, further studies are still required to further determine the physiological mechanisms behind this effect.

Dietary Melatonin Supplementation Could Be a Promising Preventing/Therapeutic Approach for a Variety of Liver Diseases

In the therapeutic strategies, the role of diet is a well-established factor that can also have an important role in liver diseases. Melatonin, identified in animals, has many antioxidant properties and it was after discovered also in plants, named phytomelatonin. These substances have a positive effect during aging and in pathological conditions too. In particular, it is important to underline that the amount of melatonin produced by pineal gland in human decreases during lifetime and its reduction in blood could be related to pathological conditions in which mitochondria and oxidative stress play a pivotal role. Moreover, it has been indicated that melatonin/phytomelatonin containing foods may provide dietary melatonin, so their ingestion through balanced diets could be sufficient to confer health benefits. In this review, the classification of liver diseases and an overview of the most important aspects of melatonin/phytomelatonin, concerning the differences among their synthesis, their presence in foods and their role in health and diseases, are summarized. The findings suggest that melatonin/phytomelatonin supplementation with diet should be considered important in preventing different disease settings, in particular in liver. Currently, more studies are needed to strengthen the potential beneficial effects of melatonin/phytomelatonin in liver diseases and to better clarify the molecular mechanisms of action.

Diabetes Mellitus and Liver Surgery: The Effect of Diabetes on Oxidative Stress and Inflammation

Diabetes mellitus (DM) is a metabolic disorder characterized by hyperglycaemia and high morbidity worldwide. The detrimental effects of hyperglycaemia include an increase in the oxidative stress (OS) response and an enhanced inflammatory response. DM compromises the ability of the liver to regenerate and is particularly associated with poor prognosis after ischaemia-reperfusion (I/R) injury. Considering the growing need for knowledge of the impact of DM on the liver following a surgical procedure, this review aims to present recent publications addressing the effects of DM (hyperglycaemia) on OS and the inflammatory process, which play an essential role in I/R injury and impaired hepatic regeneration after liver surgery.

Evaluation of the Antioxidant and Antiglycation Effects of Lactarius deterrimus and Castanea sativa Extracts on Hepatorenal Injury in Streptozotocin-Induced Diabetic Rats

The present study aimed to investigate the beneficial effects of the treatment with extracts from the edible mushroom Lactarius deterrimus (Ld) and the chestnut Castanea sativa (Cs), separately and in combination (MIX Ld/Cs), on oxidative stress and advanced glycation end-product (AGE)-mediated hepatorenal injury in a rat model of streptozotocin (STZ)-induced diabetes by examining pathways responsible for maintenance of redox homeostasis. An experimental model of diabetes was induced in rats by the administration of 40 mg/kg STZ intraperitoneally (i.p.) for 5 consecutive days. The examined extracts were applied separately at a dose of 60 mg/kg i.p. and in combination (60 mg/kg each extract; i.p.) for 4 weeks, starting from the last day of STZ administration. The improvement of hepatorenal function in diabetic rats treated with the extracts was associated with an improved glycemic and lipid status and suppression of oxidative stress and thereby oxidative damage of lipids and DNA. Besides the fact that both extracts inhibited protein glycation and AGE formation in vitro, they also reduced non-enzymatic glycosylation in diabetic rats in vivo. The observed antiglycation activity of the examined extracts (separately and in combination) was accompanied with the inhibition of CML-mediated RAGE/NF-κB activation and reduction of enzymatic O-GlcNAcylation in liver and kidney tissues of diabetic rats. Taken together, these results reveal that the administration of chestnut and mushroom extracts, either individually or together, activates a coordinated cytoprotective response against diabetes-induced hepatorenal injury not only through recovery of the antioxidant defense system of the cell, but also through a marked antiglycation activity.

Ratiometric photoacoustic imaging of endoplasmic reticulum polarity in injured liver tissues of diabetic mice

As one of the complications of diabetes, liver injury results in significant hazards. Therefore, accurately diagnosing diabetes-induced liver injury beforehand is crucial for the warning and treatment of hepatic diseases. Diabetes-induced liver injury can cause changes in the microstructure and morphology of liver tissue, leading to changes in the hydrophilic and hydrophobic domains in the endoplasmic reticulum (ER), which is closely associated with changes in cellular ER polarity. So, differences in the ER polarity can indicate the degree of diabetes-induced liver injury. Herein, we develop a new fluorescent and photoacoustic dual-mode probe, ER-P, for detection of the ER polarity of liver tissue in normal and diabetic mice. Upon excitation with a 633 nm laser, ER-P showed increasing fluorescence intensity at 800 nm accompanying a decline in the polarity. Due to its polarity-sensitivity, ER-P was utilized for confocal fluorescence imaging in live cells, and the results demonstrate that ER-P can exclusively accumulate in the ER and indicate an increase in the polarity during ER stress. Importantly, ER-P displayed different absorbance intensities at 700 nm and 800 nm in different polarity environments because of intramolecular charge transfer. The photoacoustic intensity ratios between 700 nm and 800 nm will enable quantification of polarity to be achieved. The ratiometric photoacoustic imaging data demonstrate that the polarity of the liver tissue of diabetic mice is higher than that of the liver tissue of normal mice. Meanwhile, after treatment with the antidiabetic drug metformin, diabetic mice exhibit a reduced polarity environment in their liver tissue. The proposed study may serve as a new approach for the early diagnosis and therapeutic evaluation of diabetes-induced liver injury.

Effect of melatonin versus vitamin D as antioxidant and Hepatoprotective agents in STZ-induced diabetic rats

Background

Diabetes mellitus (DM) is a serious chronic disease, with multiple complications including hepatopathy associated with imbalance of the oxidative status. The purpose of this study is to observe possible protective effects of vitamin-D and melatonin on glucose profile, antioxidant-oxidant status, lipid peroxidation, and histopathological protection of the liver in streptozotocin-induced diabetic rats.

Methods

Eighty three male albino rats were divided into nine groups as follows: G1 (n = 10) Normal control rats; G2 (n = 8) were normal rats treated with melatonin only; G3 (n = 10) were normal rats treated with vitamin D only; G4 (n = 9) were diabetic rats, which received no medications; G5 (n = 8) were diabetic rat treated with insulin only; G6 (n = 10) were diabetic rats treated with melatonin only; G7 (n = 9) were diabetic rats treated with melatonin and insulin; G8 (n = 9) were diabetic rats treated with vitamin D only; G9 (n = 10) were diabetic rats treated with vitamin D and insulin. Two months post treatment, blood was collected to measure: Fasting blood sugar (FBS), glycosylated hemoglobin (HbA1c), fructosamine (FA), total antioxidant capacity (TAC), malondialdahyde (MDA). livers were isolated for histopathological study.

Results

As compared to normal rats, our results demonstrate that glucose, fructosamine and HbA1c levels is increased in diabetic groups and declined to lesser levels in treated groups. TAC level of diabetic rats is not significantly changed. Vitamin D administration significantly increased TAC while it is not changed with melatonin either in treated or non-treated groups. The liver of diabetic rats shows only mild focal microvesicular fatty degeneration. The liver of diabetic rats treated with insulin shows degeneration of cell edema in the stroma. The liver of diabetic rats treated with melatonin with or without insulin, exhibited marked improvement. The liver of diabetic rats treated with vitamin D with or without insulin, shows degeneration of cells and edema in the stroma.

Conclusion

Our results demonstrated the beneficial antioxidant effect of vitamin D administration to normal and diabetic rats as compared to melatonin. Nevertheless, melatonin still shows more therapeutic effect on liver cell injury induced by induction of diabetes.

Effects of Melatonin on Liver Injuries and Diseases

Liver injuries and diseases are serious health problems worldwide. Various factors, such as chemical pollutants, drugs, and alcohol, could induce liver injuries. Liver diseases involve a wide range of liver pathologies, including hepatic steatosis, fatty liver, hepatitis, fibrosis, cirrhosis, and hepatocarcinoma. Despite all the studies performed up to now, therapy choices for liver injuries and diseases are very few. Therefore, the search for a new treatment that could safely and effectively block or reverse liver injuries and diseases remains a priority. Melatonin is a well-known natural antioxidant, and has many bioactivities. There are numerous studies investigating the effects of melatonin on liver injuries and diseases, and melatonin could regulate various molecular pathways, such as inflammation, proliferation, apoptosis, metastasis, and autophagy in different pathophysiological situations. Melatonin could be used for preventing and treating liver injuries and diseases. Herein, we conduct a review summarizing the potential roles of melatonin in liver injuries and diseases, paying special attention to the mechanisms of action.

Short-term administration of melatonin or ghrelin on diabetic rats: effects on angiotensin II and vasopressin-induced uterine contractility

The aim of the present study was to investigate the effects of Angiotensin II (Ang II) and Arginin-Vasopressin (AVP) on contractility of non-pregnant uterus in diabetic Wistar rats and to explore whether one-week administration of Melatonin (MLT) or Ghrelin (GHR) will change the response of diabetic uterine muscle to AngII and AVP. Uterine horns, prepared by the method of isolated tissues were investigated as well as glycemic profile, blood pressure and body weight. The research of smooth muscle contractions was made by a new method of analysis, characterizing in detail the various phases of the myometrial activity. Differences in the development of the peptide-mediated smooth muscle contractions depending on the phase of the estrous cycle were observed. Experimental diabetes had a pronounced negative effect on force and time-parameters of AngII and AVP-stimulated uterine contractions. Administration of GHR or MLT had a beneficial effect on the glycemic status of diabetic rats and partially improved the response of uterine preparations to the peptides. The application of MLT increased both force and time-parameters of Ang II-and AVP-stimulated uterine contractions while treatment with GHR increased power characteristics and shortened contraction and relaxation of the smooth muscle process.

Investigation of lipid peroxidation and antiapoptotic effects of zinc aganist liver damage in diabetic rats

Several mechanisms for the pathogenesis of diabetic complications have been proposed, one of which is abnormal zinc (Zn) homeostasis. Zn is necessary for proper liver function since it has important antioxidant, anti-inflammatory, and antiapoptotic properties. We aimed to investigate whether or not Zn has morphologically protective effect on diabetes-induced liver damage in rats. In addition, we have investigated the role of Zn supplementation on apoptosis, lipid peroxidation levels, and the distribution of metallothionein (MT) in diabetic liver tissue. Wistar albino rats were divided into four groups: control, Zn, diabetic, and Zn-diabetic group. Experimental diabetes was induced by a single-dose streptozotocin intraperitoneally and Zn was administrated via gastric gavage tube for 6 weeks. MT expressions were showed with immunohistochemical staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay was used for apoptosis. Also, Zn, MT, and malondialdehyde (MDA) levels were determined in liver of rats. MDA levels of the Zn-supplemented diabetic group was less than the diabetic group though MT levels were increased. The number of apoptotic cells per unit area was found to be significantly decreased in this group. In the Zn-supplemented diabetic group, fibrotic tissue density and the collagen tissue density were observed less than the diabetic group. MT immunoreactivity was observed less in Zn-supplemented diabetic group. In conculusion, the present study indicated that Zn has a potential in preventing or even repairing effect against diabetic damage of the liver cells by increasing expression of MT and by reducing the apoptotic cell death and the oxidative stress.

Improvement in Serum Biochemical Alterations and Oxidative Stress of Liver and Pancreas following Use of Royal Jelly in Streptozotocin-Induced Diabetic Rats

OBJECTIVE

This study aimed to evaluate the effects of royal jelly (RJ) on serum biochemical alterations and oxidative stress status in liver and pancreas of streptozotocin (STZ)- induced diabetic rats.

MATERIALS AND METHODS

In this experimental study, thirty two male Wistar rats were divided into the following four groups (n=8/group): i. Control (C), ii. Diabetic (D), iii. Royal jelly (R), and iv. Royal jelly-treated diabetic (D/R) groups. Diabetes was induced by single intraperitoneal (IP) injection of STZ (60 mg/kg). The RJ [100 mg/kg body weight (BW)] was administered orally for 42 days. Blood samples were used to determine serum levels of insulin, high density lipoprotein cholesterol (HDL-c), total protein (TP), albumin, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and fasting blood glucose (FBG). Also, the antioxidant status was evaluated by determining the levels of malondialdehyde (MDA), catalase (CAT) and ferric reducing antioxidant power (FRAP) in liver and pancreas. Data were analyzed by one-way analysis of variance (ANOVA) with P<0.05 as the significant level.

RESULTS

STZ-induced diabetic rats showed a significant elevation in the serum levels of AST, ALT, ALP and FBG, whereas there was a significant decrease in serum levels of insulin, albumin, HDL-c and TP (P<0.05). Treatment of the diabetic rats with RJ restored the changes of the above parameters to their normal levels (P<0.05). In addition, RJ significantly improved reduced levels of FRAP and CAT as well as high MDA level in liver and pancreas (P<0.05).

CONCLUSION

RJ improves oxidative damage induced by STZ in the liver and pancreas of rats; therefore, it can be considered as an effective and alternative treatment for diabetes.

Combined therapy with metformin and insulin attenuates systemic and hepatic alterations in a model of high-fat diet-/streptozotocin-induced diabetes

In this study we have explored the pathogenesis of the hepatic alterations which occur in diabetes and the modulation of these complications by the combination of metformin adjunct treatment and insulin monotherapy. For this purpose, diabetic rats were treated with insulin (DM + Ins) or metformin plus insulin (DM + Met + Ins). Biochemical and cardiometabolic parameters were analysed by spectrophotometry. Intravital microscopy was used to study the hepatic microcirculation. In the liver tissue, real-time PCR was used to analyse oxidative stress enzymes, inflammatory markers and receptors for advanced glycation end products (AGE) (RAGE) gene expression. Lipid peroxidation was assessed by thiobarbituric acid reactive species (TBARs) analyses. AGE deposition and RAGE protein expression were studied by fluorescence spectrophotometry and Western blot respectively. Body weight, %HbA1c , urea, total proteins and oxidative stress parameters were found to be similarly improved by insulin or Met + Ins treatments. On the other hand, Met + Ins treatment showed a more pronounced effect on fasting blood glucose level than insulin monotherapy. Fructosamine, uric acid, creatinine, albumin and amylase levels and daily insulin dose requirements were found to be only improved by the combined Met + Ins treatment. Liver, renal and pancreatic dysfunction markers were found to be more positively affected by metformin adjunct therapy when compared to insulin treatment. Liver microcirculation damage was found to be completely protected by Met + Ins treatment, while insulin monotherapy showed no effect. Our results suggest that oxidative stress, microcirculatory damage and glycated proteins could be involved in the aetiology of liver disease due to diabetes. Additionally, metformin adjunct treatment improved systemic and liver injury in induced diabetes and showed a more pronounced effect than insulin monotherapy.

Melatonin, quercetin and resveratrol attenuates oxidative hepatocellular injury in streptozotocin-induced diabetic rats

In this study, effects of melatonin, quercetin and resveratrol on hepatocellular injury in streptozotocin (STZ)-induced experimental diabetes were aimed to be investigated by histological and biochemical methods. Thirty-five male Wistar albino rats were divided into five groups, namely, control, diabetes (STZ 45 mg/kg/single dose/intraperitoneally (ip)), diabetes + melatonin (10 mg/kg/30 days/ip), diabetes + quercetin (25 mg/kg/30 days/ip) and diabetes + resveratrol (10 mg/kg/30 days/ip). Initial and final blood glucose levels and body weights (BWs) were measured. At the end of the experimentation, following routine tissue processing procedure, sections were stained with haematoxylin-eosin (H-E), periodic acid Schiff and Masson's trichrome. Tissue malondialdehyde (MDA) and glutathione (GSH) levels and superoxide dismutase (SOD) and catalase (CAT) activities were examined. The diabetic rats had significantly higher blood glucose levels than those of control rats (p = 0.0001). Mean BWs of diabetic rats were significantly decreased when compared with the control rats (p = 0.0013). Histopathological alterations including cellular glycogen depletion, congestion, sinusoidal dilatation, inflammation and fibrosis were detected in diabetes group. On the other hand, histopathological changes markedly reduced in all of the treatment groups (p = 0.001). Mean tissue MDA level was increased but mean tissue CAT and SOD activities and GSH levels were decreased in the diabetes group. Melatonin, quercetin and resveratrol administered diabetic rats showed an increase in CAT activities and GSH levels and a decrease in MDA levels (p < 0.05, for all). Melatonin, quercetin and resveratrol administrations markedly reduced hepatocellular injury in STZ-induced experimental diabetes.

Mechanisms of Diabetes-Induced Liver Damage: The role of oxidative stress and inflammation

Diabetes mellitus is a non-communicable disease that occurs in both developed and developing countries. This metabolic disease affects all systems in the body, including the liver. Hyperglycaemia, mainly caused by insulin resistance, affects the metabolism of lipids, carbohydrates and proteins and can lead to non-alcoholic fatty liver disease, which can further progress to non-alcoholic steatohepatitis, cirrhosis and, finally, hepatocellular carcinomas. The underlying mechanism of diabetes that contributes to liver damage is the combination of increased oxidative stress and an aberrant inflammatory response; this activates the transcription of pro-apoptotic genes and damages hepatocytes. Significant involvement of pro-inflammatory cytokines-including interleukin (IL)-1β, IL-6 and tumour necrosis factor-α-exacerbates the accumulation of oxidative damage products in the liver, such as malondialdehyde, fluorescent pigments and conjugated dienes. This review summarises the biochemical, histological and macromolecular changes that contribute to oxidative liver damage among diabetic individuals.

Protective Effects of Melatonin on Retinal Inflammation and Oxidative Stress in Experimental Diabetic Retinopathy

Oxidative stress and inflammation are important pathogenic factors contributing to the etiology of diabetic retinopathy (DR). Melatonin is an endogenous hormone that exhibits a variety of biological effects including antioxidant and anti-inflammatory functions. The goals of this study were to determine whether melatonin could ameliorate retinal injury and to explore the potential mechanisms. Diabetes was induced by a single intraperitoneal (i.p.) injection of STZ (60 mg/kg) in Sprague-Dawley rats. Melatonin (10 mg kg(-1) daily, i.p.) was administered from the induction of diabetes and continued for up to 12 weeks, after which the animals were sacrificed and retinal samples were collected. The retina of diabetic rats showed depletion of glutathione and downregulation of glutamate cysteine ligase (GCL). Melatonin significantly upregulated GCL by retaining Nrf2 in the nucleus and stimulating Akt phosphorylation. The production of proinflammatory cytokines and proteins, including interleukin 1β, TNF-α, and inducible nitric oxide synthase (iNOS), was inhibited by melatonin through the NF-κB pathway. At 12 weeks, melatonin prevented the significant decrease in the ERG a- and b-wave amplitudes under the diabetic condition. Our results suggest potent protective functions of melatonin in diabetic retinopathy. In addition to being a direct antioxidant, melatonin can exert receptor-mediated signaling effects to attenuate inflammation and oxidative stress of the retina.

Role of stem cells during diabetic liver injury

Diabetes mellitus is one of the most severe endocrine metabolic disorders in the world that has serious medical consequences with substantial impacts on the quality of life. Type 2 diabetes is one of the main causes of diabetic liver diseases with the most common being non-alcoholic fatty liver disease. Several factors that may explain the mechanisms related to pathological and functional changes of diabetic liver injury include: insulin resistance, oxidative stress and endoplasmic reticulum stress. The realization that these factors are important in hepatocyte damage and lack of donor livers has led to studies concentrating on the role of stem cells (SCs) in the prevention and treatment of liver injury. Possible avenues that the application of SCs may improve liver injury include but are not limited to: the ability to differentiate into pancreatic β-cells (insulin producing cells), the contribution for hepatocyte regeneration, regulation of lipogenesis, glucogenesis and anti-inflammatory actions. Once further studies are performed to explore the underlying protective mechanisms of SCs and the advantages and disadvantages of its application, there will be a greater understand of the mechanism and therapeutic potential. In this review, we summarize the findings regarding the role of SCs in diabetic liver diseases.

Melatonin prevents hyperglycemia in a model of sleep apnea

OBJECTIVE

Obstructive sleep apnea is a common disorder associated with aging and obesity. Apneas cause repeated arousals, intermittent hypoxia, and oxidative stress. Changes in glucolipidic profile occur in apnea patients, independently of obesity. Animal models of sleep apnea induce hyperglycemia. This study aims to evaluate the effect of the antioxidants melatonin and N-acetylcysteine on glucose, triglyceride, and cholesterol levels in animals exposed to intermittent hypoxia.

MATERIALS AND METHODS

Two groups of Balb/c mice were exposed to intermittent hypoxia (n = 36) or sham intermittent hypoxia (n = 36) for 35 days. The intermittent hypoxia group underwent a total of 480 cycles of 30 seconds reducing the inspired oxygen fraction from 21% to 7 ± 1% followed by 30 seconds of normoxia, during 8 hours daily. Melatonin or N-acetylcysteine were injected intraperitonially daily from day 21 on.

RESULTS

At day 35, glucose levels were significantly higher in the intermittent hypoxia group than in the control group. The intermittent hypoxia groups receiving N-acetylcysteine and vehicle showed higher glucose levels than the group receiving melatonin. The lipid profile was not affected by intermittent hypoxia or antioxidant administration.

CONCLUSIONS

The present results suggest that melatonin prevents the well-recognized increase in glucose levels that usually follows exposure to intermittent hypoxia. Further exploration of the role of melatonin in sleep apnea is warranted.

Melatonin reduces hepatic mitochondrial dysfunction in diabetic obese rats

Hepatic mitochondrial dysfunction is thought to play a role in the development of liver steatosis and insulin resistance, which are both common characteristics of obesity and type 2 diabetes mellitus (T2DM). It was hypothesized that the antioxidant properties of melatonin could potentially improve the impaired functions of hepatic mitochondria in diabetic obese animals. Male Zucker diabetic fatty (ZDF) rats and lean littermates (ZL) were given either melatonin (10 mg/kg BW/day) orally for 6 wk (M-ZDF and M-ZL) or vehicle as control groups (C-ZDF and C-ZL). Hepatic function was evaluated by measurement of serum alanine transaminase and aspartate transaminase levels, liver histopathology and electron microscopy, and hepatic mitochondrial functions. Several impaired functions of hepatic mitochondria were observed in C-ZDF in comparison with C-ZL rats. Melatonin treatment to ZDF rats decreases serum levels of ALT (P < 0.001), alleviates liver steatosis and vacuolation, and also mitigates diabetic-induced mitochondrial abnormalities, glycogen, and lipid accumulation. Melatonin improves mitochondrial dysfunction in M-ZDF rats by increasing activities of mitochondrial citrate synthase (P < 0.001) and complex IV of electron transfer chain (P < 0.05) and enhances state 3 respiration (P < 0.001), respiratory control index (RCR) (P < 0.01), and phosphorylation coefficient (ADP/O ratio) (P < 0.05). Also melatonin augments ATP production (P < 0.05) and diminishes uncoupling protein 2 levels (P < 0.001). These results demonstrate that chronic oral melatonin reduces liver steatosis and mitochondria dysfunction in ZDF rats. Therefore, it may be beneficial in the treatment of diabesity.

Vitis vinifera (Muscat Variety) Seed Ethanolic Extract Preserves Activity Levels of Enzymes and Histology of the Liver in Adult Male Rats with Diabetes

The effect of V. vinifera seeds on carbohydrate metabolizing enzymes and other enzymes of the liver in diabetes is currently unknown. We therefore investigated changes in the activity levels of these enzymes following V. vinifera seed extract administration to diabetic rats. Methods. V. vinifera seed ethanolic extract (250 and 500 mg/kg/day) or glibenclamide (600 μg/kg/day) was administered to streptozotocin-induced male diabetic rats for 28 consecutive days. At the end of treatment, liver was harvested and activity levels of various liver enzymes were determined. Levels of thiobarbituric acid reactive substances (TBARS) were measured in liver homogenates and liver histopathological changes were observed. Results. V. vinifera seed ethanolic extract was able to prevent the decrease in ICDH, SDH, MDH, and G-6-PDH and the increase in LDH activity levels in liver homogenates. The seed extract also caused serum levels of ALT, AST, ALP, ACP, GGT, and total bilirubin to decrease while causing total proteins to increase. Additionally, the levels of ALT, AST, and TBARS in liver homogenates were decreased. Histopathological changes in the liver were reduced. Conclusion. Near normal activity levels of various enzymes and histology of the liver following V. vinifera seed ethanolic extract administration may be due to decrease in liver oxidative stress in diabetes.

Curcumin ameliorates streptozotocin-induced liver damage through modulation of endoplasmic reticulum stress-mediated apoptosis in diabetic rats

We investigated the effect of curcumin on liver injury in diabetic rats induced by streptozotocin (STZ) through modulation of endoplasmic reticulum stress (ERS) and unfolded protein response (UPR). Experimental diabetes was induced by a single intraperitoneal injection of STZ (55 mg/kg), and curcumin was given at 100 mg/kg by gavage for 56 days. We observed that curcumin improved the morphological and histopathological changes, significantly decreased hepatic ERS marker protein: glucose-regulated protein 78, and improved liver function in diabetic rats. Moreover, treatment with curcumin markedly decreased the sub-arm of the UPR signaling protein such as phospho-double-stranded RNA-dependent protein kinase-like ER kinase, CCAAT/enhancer-binding protein homologous protein, tumor necrosis factor receptor-associated factor 2, and inositol-requiring enzyme1α; and inhibited tumor necrosis factor α, interleukin 1β, phospho-p38 mitogen-activated protein kinase, and apoptosis signal-regulating kinase 1 in liver tissues of diabetic rats. Apoptotic and anti-apoptotic signaling proteins, such as cleaved caspase-3 and B-cell lymphoma 2, were significantly increased and decreased, respectively in diabetic rats; curcumin treatment prevented all of these alterations. In summary, our results indicate that curcumin has the potential to protect the diabetic liver by modulating hepatic ERS-mediated apoptosis, and provides a novel therapeutic strategy for the diabetic liver damage.

Alloxan-induced diabetes causes morphological and ultrastructural changes in rat liver that resemble the natural history of chronic fatty liver disease in humans

PURPOSE

This study evaluated the long-term effects of alloxan-induced diabetes in rat liver.

METHODS

Thirty nondiabetic control rats (NC) and 30 untreated diabetic (UD) rats were divided into three subgroups sacrificed after 6, 14, or 26 weeks. Clinical and laboratory parameters were assessed. Fresh liver weight and its relationship with body weight were obtained, and liver tissue was analyzed.

RESULTS

UD rats showed sustained hyperglycemia, high glycosylated hemoglobin, and low plasma insulin. High serum levels of AST and ALT were observed in UD rats after 2 weeks, but only ALT remained elevated throughout the experiment. Fresh liver weight was equal between NC and UD rats, but the fresh liver weight/body weight ratio was significantly higher in UD rats after 14 and 26 weeks. UD rats showed liver morphological changes characterized by hepatic sinusoidal enlargement and micro- and macrovesicular hepatocyte fatty degeneration with progressive liver structure loss, steatohepatitis, and periportal fibrosis. Ultrastructural changes of hepatocytes, such as a decrease in the number of intracytoplasmic organelles and degeneration of mitochondria, rough endoplasmic reticulum, and nuclei, were also observed.

CONCLUSION

Alloxan-induced diabetes triggered liver morphological and ultrastructural changes that closely resembled human disease, ranging from steatosis to steatohepatitis and liver fibrosis.

Antioxidants inhibit the inflammatory and apoptotic processes in an intermittent hypoxia model of sleep apnea

BACKGROUND

Sleep apnea causes intermittent hypoxia (IH). We aimed to investigate the proteins related to oxidative stress, inflammation and apoptosis in liver tissue subjected to IH as a simulation of sleep apnea in conjunction with the administration of either melatonin (MEL, 200 μL/kg) or N-acetylcysteine (NAC, 10 mg/kg).

METHODS

Seventy-two adult male Balb-C mice were divided: simulation of IH (SIH), SIH + MEL, SIH + NAC, IH, IH + MEL and IH + NAC. The animals were subjected to simulations of sleep apnea for 8 h a day for 35 days. The data were analyzed with ANOVA and Tukey tests with the significance set at p < 0.05.

RESULTS

In IH, there was a significant increase in oxidative stress and expression of HIF-1a. In addition, we observed increase in the activation levels of NF-kB. This increase may be responsible for the increased expression of TNF-alpha and iNOS as well as the significant increase of VEGF signaling and expression of caspase-3 and caspase-6, which suggests an increase in apoptosis. In the groups treated with antioxidants, the analysis showed that the enzyme activity and protein levels were similar to those of the non-simulated group.

CONCLUSIONS

Thus, we show that IH causes liver inflammation and apoptosis, which may be protected with either MEL or NAC.

Antihyperglycemic, hypolipidemic, hepatoprotective and antioxidative effects of dietary clove (Szyzgium aromaticum) bud powder in a high-fat diet/streptozotocin-induced diabetes rat model

BACKGROUND

Syzygium aromaticum (L.) Merr. & Perry (clove) bud is an important spice used in the preparation of several delicacies and in folklore for diabetes management. The present study was convened to assess the effects of dietary clove bud powder (CBP) on biochemical parameters in a type 2 diabetes rat model, induced by a combination of high-fat diet and low-dose streptozotocin (35 mg kg⁻¹) for 30 days.

RESULTS

Diabetic rats were placed on dietary regimen containing 20-40 g kg⁻¹ clove bud powder. The results revealed that there was no significant (P > 0.05) difference in the average feed intake and weight changes between the rat groups. Furthermore, supplementation with CBP gradually reduced blood glucose level in diabetic rat compared to control diabetic rats without CBP supplementation (DBC). Moreover, reduced activity of α-glucosidase was observed in CBP and metformin-treated rat groups when compared to that of the DBC rat group. In addition, the DBC group had significantly (P < 0.05) higher lipid concentrations (except for high-density lipoprotein cholesterol) when compared to all other groups. Furthermore, CBP had significantly (P < 0.05) reduced activity of liver enzymes (alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase) and showed elevated levels of antioxidant status (glutathione, ascorbic acid, superoxide dismutase and catalase).

CONCLUSION

The results suggest that the clove bud diet may attenuate hyperglycemia, hyperlipidemia, hepatotoxicity and oxidative stress in the type 2 diabetic condition.

Serum IGF-1 levels correlate negatively to liver damage in diabetic rats

Diabetes and insulin resistance frequently cause liver damage. Diabetes also causes reduction in liver and blood IGF-1 levels. We investigated the relation between liver damage and IGF-1 levels in diabetic rats. Fourteen Wistar albino rats were divided into control and diabetic groups. Diabetes was induced by streptozotocin. Rats were sacrificed for biochemical and histologic examinations 2 weeks after streptozotocin injection. Serum and liver IGF-1 levels were decreased, liver malondialdehyde (MDA) levels were increased, glutathione peroxidase (GPx) enzymes activities were decreased and serum alanine aminotransferase (ALT) levels were increased in diabetic group. Microscopic examination of liver revealed that normal tissue organization was disrupted in streptozotocin-induced diabetic rats. There was a strongly positive correlation between blood glucose levels and liver injury, and blood and liver IGF-1 levels. There was a strongly negative correlation between blood IGF-1 levels and hepatic injury. Our results suggest that reduction of blood IGF-1 levels correlates with hepatic injury and circulating IGF-1 levels may have predictive value for determining hepatic damage that results from diabetes. In addition, circulating IGF-1 levels are correlated with glutathione levels and the oxidative stress status of diabetic rat liver.

Decreased O-GlcNAcylation of the key proteins in kinase and redox signalling pathways is a novel mechanism of the beneficial effect of α-lipoic acid in diabetic liver

The present study aimed to investigate the effects of the treatment with a-lipoic acid (LA), a naturally occurring compound possessing antioxidant activity, on liver oxidant stress in a rat model of streptozotocin (STZ)-induced diabetes by examining potential mechanistic points that influence changes in the expression of antioxidant enzymes such as catalase (CAT) and CuZn/Mn superoxide dismutase(s) (SOD). LA was administered for 4 weeks by daily intraperitoneal injections (10 mg/kg) to STZ-induced diabetic rats, starting from the last STZ treatment. LA administration practically normalised the activities of the indicators of hepatocellular injury, alanine and aspartate aminotransferases, and lowered oxidative stress, as observed by the thiobarbituric acid-reactive substance assay, restored the reduced glutathione:glutathione disulphide ratio and increased the protein sulfhydryl group content. The lower level of DNA damage detected by the comet assay revealed that LA reduced cytotoxic signalling, exerting a hepatoprotective effect. The LA-treated diabetic rats displayed restored specific enzymatic activities of CAT, CuZnSOD and MnSOD. Quantitative real-time PCR analysis showed that LA restored CAT gene expression to its physiological level and increased CuZnSOD gene expression, but the gene expression of MnSOD remained at the diabetic level. Although the amounts of CAT and CuZnSOD protein expression returned to the control levels, the protein expression of MnSOD was elevated. These results suggested that LA administration affected CAT and CuZnSOD expression mainly at the transcriptional level, and MnSOD expression at the post-transcriptional level. The observed LA-promoted decrease in the O-GlcNAcylation of extracellular signal-regulated kinase, protein 38 kinase, NF-kB, CCAAT/enhancer-binding protein and the antioxidative enzymes themselves in diabetic rats suggests that the regulatory mechanisms that supported the changes in antioxidative enzyme expression were also influenced by post-translational mechanisms.