Simultaneous intervention against oxidative stress and inflammation by targeting Nrf2/ARE and NLRP3 inflammasome pathway mitigates thioacetamide-induced liver fibrosis in rat

Liver fibrosis is a typical pathological state/stage involved in most chronic liver diseases and its persistence results in cirrhosis. Inflammasomes are cytoplasmic sensors that induce inflammation in response to stress. Glibenclamide (GLB) is an USFDA-approved drug for type 2 diabetes and is reported to possess anti-inflammatory activity by inhibiting inflammatory cytokines. Dimethyl fumarate (DMF) is an USFDA-approved drug for multiple sclerosis and has been reported to activate the Nrf2/ARE pathway to maintain the cellular antioxidant balance. A total of 36 rats were randomized into six groups (n = 6 each). The rats were injected with thioacetamide (TAA) 200 mg/kg, intraperitoneally every third day for eight consecutive weeks to induce liver fibrosis and oral treatment of GLB 0.5 mg/kg/day and DMF 25 mg/kg/day, and their combinations were provided for the last four consecutive weeks. Treatment with GLB, DMF, and GLB+DMF significantly protected against TAA-mediated oxidative stress and inflammatory conditions by improving hepatic function test, triglycerides, hydroxyproline, and histopathological alterations, by inhibiting the NLRP3 inflammasome signaling and fibrogenic markers, and by activating Nrf2/ARE pathway in Wistar rats. The present results suggest that simultaneous Nrf2/ARE activation and NLRP3 inflammasome inhibition could significantly contribute to developing a novel therapy for patients with liver fibrosis.

Dimethyl fumarate-mediated Nrf2/ARE pathway activation and glibenclamide-mediated NLRP3 inflammasome cascade inhibition alleviate type II diabetes-associated fatty liver in rats by mitigating oxidative stress and inflammation

The prevalence of nonalcoholic fatty liver disease (NAFLD) is much higher in patients with type II diabetes (T2D). Inflammasomes are multimolecular complexes reported to involve inflammatory conditions. The nuclear factor (erythroid-derived 2)-like factor 2/antioxidant responsive element (Nrf2/ARE) pathway is an important regulator of antioxidant status in cells. Antidiabetic drug glibenclamide (GLB) is reported as  NACHT, leucine-rich repeat, and pyrin domain domains-containing protein 3 (NLRP3) inflammasome inhibitor, whereas anti-multiple sclerosis drug dimethyl fumarate (DMF) is reported as an Nrf2/ARE pathway activator. Both GLB and DMF possess anti-inflammatory and antioxidant properties, therefore, the hypothesis was made to look into the alone as well as the combination potential of GLB, DMF, and GLB + DMF, against NAFLD in diabetic rats. This study was aimed to investigate (1) the involvement of NLRP3 inflammasome and Nrf2/ARE signaling in diabetes-associated NAFLD (2) the effect of GLB, DMF, GLB + DMF, and metformin (MET) interventions on NLRP3 inflammasome and Nrf2/ARE signaling in diabetes-associated NAFLD. The rats were injected with streptozotocin (STZ) 35 mg/kg and fed a high-fat diet (HFD) for 17 consecutive weeks to induce diabetic NAFLD. The oral treatment of GLB 0.5 mg/kg/day, DMF 25 mg/kg/day, their combination and MET 200 mg/kg/day, were provided from the 6th to the 17th week. Treatment with GLB, DMF, GLB + DMF, and MET significantly alleviated HFD + STZ-induced plasma glucose, triglycerides, cholesterol, %HbA1c, hepatic steatosis, NLRP3, apoptosis-associated speck-like protein containing a caspase activation and recruitment domain, CARD, caspase-1, interleukin-1β (IL-1β), nuclear factor-κB (NF-κB), Nrf2, superoxide dismutase 1, catalase, IGF 1, heme oxygenase 1, receptor for the advanced glycation end product (RAGE), and collagen-1 in diabetic rats. Further, a mechanistic molecular study employing other specific NLRP3 inhibitors and Nrf2 activators will significantly contribute to the development of novel therapy for fatty liver diseases.

Simultaneous Modulation of NLRP3 Inflammasome and Nrf2/ARE Pathway Rescues Thioacetamide-Induced Hepatic Damage in Mice: Role of Oxidative Stress and Inflammation

Chronic tissue injury resulting in fibrosis of multiple organs, responsible for one-third of the death globally. Liver fibrosis is a common pathway/condition involved in all chronic liver diseases. Thioacetamide (TAA), a hepatotoxicant, was used to induce hepatic fibrosis. Anti-diabetic drug glibenclamide (GLB) possesses anti-inflammatory properties and inhibits NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome activation. Dimethyl fumarate (DMF), a multiple sclerosis drug, activates the nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway and maintains the antioxidant status in the cell. The present study was designed to investigate (i) role of NLRP3 inflammasome and Nrf2/ARE pathway in TAA-induced hepatotoxicity and liver fibrosis, (ii) mechanism involved in GLB and DMF mediated hepatoprotection against TAA-induced hepatotoxicity, and (iii) additional/synergistic hepatoprotective effect of combination treatment with NLRP3 inhibition + Nrf2 activation or GLB + DMF or MCC950 + 4OI to reverse/ameliorate the experimental liver fibrosis completely. TAA was administered intraperitoneally to mice for seven consecutive weeks, and treatments of GLB, DMF, GLB + DMF, MCC950, 4OI, and MCC950 + 4OI were provided for the last three consecutive weeks. The intervention with GLB, DMF, GLB + DMF, MCC950, 4OI, and MCC950 + 4OI significantly protected TAA-induced oxidative stress and inflammatory conditions by improving biochemical, histological, and immunoexpression changes in mice. The GLB, DMF, and GLB + DMF intervention exhibited a better protective effect compared with MCC950, 4OI, and MCC950 + 4OI, which revealed that this specific inhibitor/activator possesses only NLRP3 inflammasome inhibitory/Nrf2 activatory properties. In contrast, the clinical drug GLB and DMF have several other beneficial effects, which are independent of NLRP3 inhibition and Nrf2 activation.

The intervention of tert-butylhydroquinone protects ethanol-induced gastric ulcer in type II diabetic rats: the role of Nrf2 pathway

Ethanol consumption increases the prevalence of gastric ulcer (GU) in rats with type II diabetes (T2D). Induction of GU by absolute ethanol (5 mL/kg or 3.94 g/kg) in the animal model resembles human ulcer characteristics. The aim was to investigate the role of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in the treatment of GU in diabetic condition. The rats were exposed to absolute ethanol 1 h before sacrifice and T2D was induced by combined exposure of high-fat diet and low dose streptozotocin. Pretreatment of tert-butylhydroquinone (tBHQ) (25 and 50 mg/kg), metformin (500 mg/kg), and omeprazole (20 mg/kg) were given once daily for last three consecutive weeks. In ethanol-exposed diabetic rats, pretreatment with tBHQ, omeprazole, and metformin reduced gastric mucosal lesion, ulcer index, histological alterations, malondialdehyde level, and apoptosis. Furthermore, the intervention of tBHQ, omeprazole, and metformin improved the integrity of the stomach mucosa, glutathione, gastric pH, collagen, and goblet cells. tBHQ treatment improved ethanol-induced alterations of Nrf2, catalase, heat shock protein 70 (HSP70), NF-κB, and endothelin-1 expressions in diabetic rats. In diabetic conditions, the incidence of GU is increased due to elevated levels of reactive oxygen species, inflammatory mediators, depleted levels of cellular antioxidants, and altered gastric parameters. The tBHQ intervention could be a rational strategy to protect these changes.

Zinc and selenium combination treatment protected diabetes-induced testicular and epididymal damage in rat

Diabetes increases the possibility of germ cell damage, hypogonadism, and male infertility. Diabetic condition negatively impacts zinc (Zn) and selenium (Se) levels in the body. Zn and Se are among the most important trace elements involved in the regulation of redox reaction, antioxidants enzymes activities, and DNA expression in a germ cell. The present study aimed to elucidate the combined effects of Zn and Se treatment on diabetes-induced germ cell damage in male Sprague Dawley rats. Type 1 diabetes was induced by the single intraperitoneal (i.p.) injection of streptozotocin (55 mg/kg). Zn (3 mg/kg, i.p.) and Se (0.5 mg/kg, i.p.) were administered daily for 8 consecutive weeks. All the animals were provided with normal feed and water throughout the study. The effects on germ cell damage were evaluated by body weight, feed-water intake, organ weight, sperm count, motility, sperm head morphology, biochemical analysis, histology, immunohistochemistry, halo assay, germ cell comet assay, testes terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end-labeling (TUNEL) assay, sperm TUNEL assay, serum protein pattern analysis, and subcellular analysis using transmission electron microscopy. Further, the expressions of nuclear erythroid-derived related factor 2, catalase, glutathione peroxidase 4, and glutathione peroxidase 5 were carried out to ascertain the mechanism of protection. The present results demonstrated that 8 weeks combined treatment of Zn (3 mg/kg, i.p.) and Se (0.5 mg/kg, i.p.) reduced diabetes-induced germ cell damage. This study further highlighted that Zn and Se combination treatment might be a better strategy for the germ cell protection in diabetes and deserve further investigation.

Ethanol-induced gastric ulcer in rats and intervention of tert-butylhydroquinone: Involvement of Nrf2/HO-1 signalling pathway

Gastric ulcer (GU) is the most common health concern that occurs due to alcohol consumption, smoking and physiological stress. Ethanol-induced GU in animal model resembles the pathophysiology of human ulcer. The present study was designed to investigate the cytoprotective and anti-inflammatory properties of tert-butylhydroquinone (tBHQ), a nuclear factor erythroid 2-related factor 2 (Nrf2) activator, against gastric mucosal damage induced by acute exposure of ethanol (5 ml/kg). The intervention of tBHQ (25 and 50 mg/kg, per os (po)) and omeprazole (20 mg/kg, po) was done for 10 consecutive days. Omeprazole was chosen as a standard drug because it is prescribed for the treatment of GU. Pretreatment of tBHQ decreased gastric mucosal lesion, ulcer index, apoptotic cells and lipid peroxidation level induced by ethanol. Furthermore, the intervention of tBHQ increased gastric mucosa integrity, pH, reduced glutathione, collagen and mucus-producing goblet cells. Intervention of tBHQ increased the expression of antioxidant markers such as Nrf2, haeme oxygenase-1 and catalase and decreased the expressions of inflammatory markers such as nuclear factor kappa-light-chain-enhancer of activated B cells and cyclooxygenase-2. The cytoprotective potential of tBHQ against gastric mucosal damage might be due to its ability to enhance cellular antioxidants and anti-inflammatory responses.

NLRP3 inhibitor glibenclamide attenuates high-fat diet and streptozotocin-induced non-alcoholic fatty liver disease in rat: studies on oxidative stress, inflammation, DNA damage and insulin signalling pathway

The prevalence of non-alcoholic fatty liver disease (NAFLD) is much higher in diabetic and obese individuals. Combined exposure of high-fat diet (HFD) and single low-dose streptozotocin (STZ) was used to induce type II diabetes-associated NAFLD, as it better replicates the human pathology of fatty liver. Glibenclamide (GLB) is a potent NLRP3 inflammasome inhibitor and possesses anti-inflammatory and anti-oxidant properties. So it was pertinent to investigate its hepatoprotective potential against NAFLD in rat. HFD was provided to rat for 17 consecutive weeks and glibenclamide (GLB; 0.5 and 2.5 mg/kg/day, orally) was administered for the last 12 consecutive weeks. Establishment of NAFLD was clearly indicated by significant increase in liver weight, glucose, triglyceride, cholesterol, % glycosylated haemoglobin and insulin levels, and GLB intervention reduced the same. GLB restored HFD-induced significant increase in ROS, MDA and decrease in GSH. Histopathological studies revealed the macro- and micro-vascular steatosis and mild degree of inflammation in HFD-fed rat compared with control, and GLB intervention reduced the same. HFD exposure significantly increased the DNA damage and apoptosis compared with control, and GLB intervention reduced the same. Immunohistochemical and immunoblotting findings showed that GLB improved the hepatic expressions of inflammatory markers (NLRP3, ASC, caspase-1, IL-1β, NF-κB), anti-oxidant markers (SOD, catalase) and insulin signalling markers (p-AKT, p-GSK-3β, p-IRS). Hepatoprotective effects of GLB was mediated by decreasing the levels of glucose, triglycerides, cholesterol, DNA damage, apoptosis and inflammatory markers, and by improving the anti-oxidant status and insulin signalling pathway in HFD fed rat.

Glibenclamide protects against thioacetamide-induced hepatic damage in Wistar rat: investigation on NLRP3, MMP-2, and stellate cell activation

Glibenclamide (GLB), most widely used in the treatment of type II diabetes mellitus, inhibits K⁺_ATP channel in pancreatic-β cells and releases insulin, while thioacetamide (TAA) is a well-known hepatotoxicant and most recommended for the induction of acute and chronic liver disease. The purpose of this study was to evaluate the hepatoprotective potential of GLB against TAA-induced hepatic damage in Wistar rats. TAA (200 mg/kg, ip, twice weekly) and GLB (1.25, 2.5, and 5 mg/kg/day, po) were administered for 6 consecutive weeks. Different biochemical, DNA damage, histopathological, TEM, immunohistochemical, and western blotting parameters were evaluated. GLB treatment has no effects on the TAA-induced significant decrease in body and liver weights. TAA treatment significantly increased liver index and treatment with GLB has no effect the same. TAA treatment altered the liver morphology, whereas treatment with GLB normalized the alteration in morphology. Further, significant increase in oxidative stress, apoptosis, and DNA damage was found in TAA-treated animals and GLB treatment significantly reduced these effects. TAA-induced plasma transaminases and serum ALP levels were significantly restored by GLB. Furthermore, histopathological findings showed the presence of lymphocyte infiltration, collagen deposition, bridging fibrosis, degeneration of portal triad, and necrosis in TAA-treated animals and GLB intervention significantly reduced the same. TEM images revealed that GLB significantly normalized the hepatic stellate cell morphology as well as restored the number of lipid droplets. GLB treatment significantly downregulated the expressions of TGF-β1, α-SMA, NLRP3, ASC, caspase-1, and IL-1β, and upregulated MMP-2 and catalase against TAA-induced liver damage. The outcomes of the present study confirmed that GLB ameliorated the liver damage induced by TAA.

Implementation of Good Laboratory Practices (GLP) in basic scientific research: Translating the concept beyond regulatory compliance

The principles of Good Laboratory Practices (GLPs) are mainly intended for the laboratories performing studies for regulatory compliances. However, today GLP can be applied to broad disciplines of science to cater to the needs of the experimental objectives, generation of quality data and assay reproducibility. Considering its significance, it can now be applied in academics; industries as well as government set ups throughout the world. GLP is the best way to promote the reliability, reproducibility of the test data and hence facilitates the international acceptability. Now it is high time to translate and implement the concept of GLP beyond regulatory studies. Thus, it can pave the way for better understanding of scientific problems and help to maintain a good human and environmental health. Through this review, we have made an attempt to explore the uses of GLP principles in different fields of science and its acceptability as well as looking for its future perspectives.

Role of Zinc Supplementation in Testicular and Epididymal Damages in Diabetic Rat: Involvement of Nrf2, SOD1, and GPX5

Zinc (Zn) is one of the most important trace elements required for several biological processes. Diabetes negatively affects many organs, and diabetic patients are often hypozincemic. The present study aims to investigate the role of Zn supplementation in the testes, epididymis, and sperms of streptozotocin (STZ)-induced diabetic rat. Serum, testicular, and sperm Zn contents were found to be altered in diabetic rat. Biochemical, histopathological, and protein expression profiles were determined to decipher the role of Zn in protecting the cellular perturbations. Further, histopathological analyses of testes and epididymis showed deranged architecture along with other noted abnormalities. Diabetic testes showed decreased Nrf2, HO-1, SOD1, PCNA, and Bcl-2 expressions whereas increased COX-2, NF-κB, MT, IL-6, and p-ERK levels. SOD1 and GPX5 were decreased in the epididymis of diabetic rat, whereas Zn supplementation attenuated these changes. The present results demonstrate the beneficial role of Zn supplementation in diabetes-associated testicular alterations of rat.

Effects of nicotine on the testicular toxicity of streptozotocin-induced diabetic rat

The aim of the present study is to investigate whether nicotine augmented the testicular toxicity and angiotensin converting enzyme inhibitor, enalapril, can ameliorate the effects in diabetic rat. Male Sprague Dawley rats were randomized into five groups: control, nicotine, diabetic, Diab + Nico, and Diab + Nico + Enal. Animals were made diabetic by single injection of streptozotocin (55 mg/kg/intraperitoneally). Nicotine dissolved in drinking water at a concentration of 100 µg/ml was given ad libitum and enalapril was given orally at a dose of 10 mg/kg/day for four consecutive weeks. After 4 weeks of treatment, animals were killed and biochemical parameters glucose, glycosylated hemoglobin, cotinine, and the testosterone levels were measured. Testicular toxicity was evaluated using sperm count, sperm comet assay, histology, and immunohistochemical staining of 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxo-dG) and the proinflammatory markers (nuclear factor kappa B (NF-κB), cyclooxygenase (COX-2), and tissue necrotic factor alpha (TNF-α)) evaluated by western blotting. Results showed that nicotine did not alter the blood glucose and glycosylated hemoglobin level, significantly decreased the sperm count and increased the sperm DNA damage. These changes were accompanied by significant increases in the 8-oxo-dG, NF-κB, COX-2, and TNF-α expression. Furthermore, the intervention of enalapril in nicotine-treated diabetic rat attenuated the testicular damage and restored sperm count, sperm DNA damage, as well as reduced the expression of NF-κB, COX-2, and TNF-α. These findings clearly suggest that nicotine not only augmented the testicular toxicity in the diabetic rat but also increases the risk of germ cell toxicity effects that were attenuated by enalapril treatment.

Protective role of sodium butyrate, a HDAC inhibitor on beta-cell proliferation, function and glucose homeostasis through modulation of p38/ERK MAPK and apoptotic pathways: study in juvenile diabetic rat

Type 1 diabetes (T1D) also known as juvenile diabetes is a chronic autoimmune disorder that precipitates in genetically susceptible individuals by environmental factors particularly during early age. Both genetic and epigenetic factors are implicated in the beta-cell development, proliferation, differentiation and function. Recent evidences suggested that there is a link between diabetes and histone deacetylases (HDACs), because HDAC inhibitors promote beta-cell development, proliferation and function as well as improve glucose homeostasis. Sodium butyrate (NaB) is a short chain fatty acid having HDAC inhibition activity. The present study was aimed to investigate the protective role of NaB treatment on the beta-cell proliferation, function and glucose homeostasis as well as apoptosis in juvenile diabetic rat. Diabetes was induced by single injection of STZ (60 mg/kg, i.p.) in chilled citrate buffer, while NaB (500 mg/kg/day) was administrated by i.p. route for 21 days as pre- and post-treatment schedule. Plasma glucose and insulin levels, HbA1c, glucose tolerance, apoptosis, and expression of proliferating cell nuclear antigen (PCNA), p38, p53, caspase-3, extracellular signal-regulated kinase-1/2 (ERK-1/2), forkhead box protein O1 (FOXO1) and insulin receptor substrate-1 (IRS-1) as well as histone acetylation were evaluated. NaB treatment decreased plasma glucose, HbA1c, beta-cell apoptosis and improved plasma insulin level and glucose homeostasis through HDAC inhibition and histone acetylation in diabetic animal as compared to control. NaB treatment improved the beta-cell proliferation, function and glucose homeostasis as well as reduced beta-cell apoptosis in juvenile diabetic rat by the modulation of p38/ERK MAPK and apoptotic pathway.

Melatonin reduces ulcerative colitis-associated local and systemic damage in mice: investigation on possible mechanisms

BACKGROUND AND AIMS

Ulcerative colitis (UC) is a chronic gastrointestinal disorder. Substantial research reveals that melatonin has beneficial effects in ulcerative colitis both experimentally and clinically. We have previously reported that ulcerative colitis was associated with local and systemic damage in mice. The purpose of this study was to reveal the novel targets of melatonin in its protective mechanism against ulcerative colitis in mice. We also wished to determine whether or not melatonin protected against ulcerative colitis-induced systemic damage in mice.

METHODS

Ulcerative colitis was induced in mice by use of 3% (w/v) dextran sulfate sodium for two cycles. One cycle comprised 7 days of DSS-treated water followed by 14 days of normal drinking water. Melatonin was administered at doses of 2, 4, or 8 mg/kg bw/day, po throughout. The effect of melatonin in mice with UC was evaluated by use of biochemical data, histological evaluation, comet and micronucleus assays, immunohistochemistry, and western blot analysis.

RESULTS

The results indicated that melatonin treatment ameliorated the severity of ulcerative colitis by modulating a variety of molecular targets, for example nuclear factor kappa B, cyclooxygenase-2, interleukin 17, signal transducer and activator of transcription 3, nuclear erythroid 2-related factor 2, matrix metalloproteinase-9, and connective tissue growth factor. Further, ulcerative colitis increased gut permeability, plasma lipopolysaccharide level, systemic inflammation, and genotoxicity. Melatonin treatment led to mucosal healing and reduced ulcerative colitis-induced elevated gut permeability and reduced the plasma LPS level, systemic inflammation, and genotoxicity.

CONCLUSION

Melatonin ameliorated ulcerative colitis-associated local and systemic damage in mice.

Effect of sodium valproate on the toxicity of cyclophosphamide in the testes of mice: influence of pre- and post-treatment schedule

Recently, sodium valproate (VPA) has been proven as histone deacetylase (HDAC) inhibitor and potentiates the cytotoxicity of anticancer drugs, and also exhibit promising anti-cancer activity. Present study aimed to investigate the influence of pre- and post-treatment of VPA on cyclophosphamide (CP) induced genotoxicity and germ cell toxicity in mice. All the animals were treated with VPA at the dose of 500 mg/kg/day on alternate day thrice/week for a period of two weeks, CP at the dose of 200 mg/kg on 7^th and 15^th day and sacrificed 24 h after administration (i.p.) of the last dose. End point of evaluation includes sperm count, sperm head morphology, sperm comet assay and histology. VPA treatment significantly decreases CP induced sperm count, testes and epididymis weight; increased sperm head abnormality and sperm DNA damage. Both VPA pre- and post-treatment augmented CP induced DNA damage and the germ cell toxicity; however, pre-treatment induced more cytotoxicity and genotoxicity as compared to post-treatment.

Ulcerative colitis-induced hepatic damage in mice: studies on inflammation, fibrosis, oxidative DNA damage and GST-P expression

There exists a close relationship between ulcerative colitis and various hepatic disorders. The present study was aimed to evaluate the hepatocellular damage in experimental colitis model. Ulcerative colitis was induced in Swiss mice by cyclic treatment with 3% w/v dextran sulfate sodium in drinking water. The severity of colitis was assessed on the basis of disease activity index and colon histology. The effect of ulcerative colitis on the liver was assessed using various biochemical parameters, histological evaluation, sirius red staining, immunohistochemical staining with peroxisome proliferator-activated receptor γ, 8-oxo-7,8-dihydro-2'-deoxyguanosine and placental glutathione S-transferase, comet assay (alkaline and modified), Terminal Deoxynucleotidyl Transferase-mediated dUTP Nick End Labeling assay and western blot analysis to detect the protein expression of nuclear factor kappa B, cyclooxygenase-2, nuclear erythroid 2-related factor 2 and NADPH: quinone oxidoreductase-1. Dextran sulfate sodium induced severe colitis in mice as evident from an elevated disease activity index and histological abnormalities. Ulcerative colitis increased the permeability of colon as apparent from a significant reduction in the expression of tight junction protein, occludin. Further, the bacterial translocation assay as well as the analysis of lipopolysaccharide level revealed the existence of various bacterial species in the liver of ulcerative colitis-induced mice. There was a significant increase in the plasma alanine and aspartate transaminases and liver triglyceride levels, expression of peroxisome proliferator-activated receptor γ, inflammatory markers, oxidative stress, fibrosis, oxidative DNA damage and apoptosis in the liver of mice. Moreover, there was an increase in the expression of nuclear factor kappa B and cyclooxygenase-2 and a reduction in the expression of nuclear erythroid 2-related factor 2 and NADPH: quinone oxidoreductase-1 in the liver of severe ulcerative colitis-induced mice. The results of the present study provide evidence that ulcerative colitis is accompanied with hepatic damage in mice.

Dextran sulfate sodium-induced ulcerative colitis leads to increased hematopoiesis and induces both local as well as systemic genotoxicity in mice

Ulcerative colitis is a chronic gastrointestinal disorder eliciting the risk of colorectal cancer, the third most common malignancy in humans. The present study was aimed to characterize dextran sulfate sodium-induced ulcerative colitis and to elucidate its influence on the bone marrow cell proliferation and the subsequent stimulation of the systemic genotoxicity in mice. Experimental colitis was induced in Swiss mice using 3% (w/v) dextran sulfate sodium in drinking water. The severity of colitis was assessed on the basis of clinical signs, colon length, oxidative stress parameters, various pro-inflammatory markers, histopathological evaluation and immunohistochemical staining of 8-oxo-7,8-dihydro-2'-deoxyguanosine in the colon of dextran sulfate sodium treated mice. Further, assessment of genotoxicity was carried out using alkaline and modified comet assays in the colon and lymphocytes and micronucleus assay in the peripheral blood of mice. For the evaluation of inflammation-induced cell proliferation in the bone marrow, proliferating cell nuclear antigen immunostaining was carried out in the bone marrow of mice. Dextran sulfate sodium induced severe colitis as evident from the elevated disease activity index, reduced colon length, increased oxidative stress, histological abnormalities and oxidative DNA damage in the colon of mice. Moreover, colitis-induced elevated prostaglandin-E2 level in the plasma of dextran sulfate sodium treated mice stimulated the cell proliferation in the bone marrow, which further triggered colitis-induced DNA damage in the peripheral blood of mice.

Alkaline, Endo III and FPG modified comet assay as biomarkers for the detection of oxidative DNA damage in rats with experimentally induced diabetes

Increased production of reactive oxygen species under diabetic condition underlines the higher oxidatively damaged DNA in different tissues. However, it is practically difficult to assess the oxidatively damaged DNA in different internal organs. Therefore, the present study was aimed to evaluate the extent of oxidative stress-induced DNA damage in different organs with the progression of diabetes. Diabetic and control Sprague Dawley rats were sacrificed in time-dependent manner and the lung, liver, heart, aorta, kidney, pancreas and peripheral blood lymphocytes (PBL) were analyzed for both alkaline and modified comet assay with endonuclease-III (Endo III) and formamidopyrimidine-DNA glycosylase (FPG) (hereafter called modified comet assay) for the detection of oxidative DNA damage. The statistically significant increase in olive tail moment (OTM) was found in all the tested tissues. The extent of DNA damage was increased with the progression of diabetes as revealed by the parameter of OTM in alkaline and modified comet assay. Further, the positive correlations were observed between OTM of the lung, liver, heart, aorta, kidney and pancreas with PBL of diabetic rat in the alkaline and modified comet assay. Moreover, significant increase in the 8-oxodG positive nuclei in the lung, liver, heart, aorta, kidney and pancreas was observed in 4th and 8th week diabetic rat as compared to control. Results of the present study clearly indicated the suitability of alkaline and modified comet assay for the detection of multi-organ oxidative DNA damage in streptozotocin (STZ)-induced diabetic rat and showed that damaged DNA of PBL can be used as a suitable biomarker to assess the internal organs response to DNA damage in diabetes.

Quercetin inhibits diethylnitrosamine-induced hepatic preneoplastic lesions in rats

Quercetin is an antioxidant flavonoid, found ubiquitously in nature and extensively used in herbal medicines and food additives. This study aimed to investigate the effect of quercetin on diethylnitrosamine-induced preneoplastic lesions, using the medium-term rat liver bioassay. The γ-benzene hexachloride was used as promoter at the doses of 0.1, 1.0, and 10.0 mg/kg against a single dose of diethylnitrosamine (200 mg/kg) in male Sprague-Dawley rats. All the rats were subjected to 70% partial hepatectomy at Week 4. The protective effect of quercetin (5 and 25 mg/kg) was examined against the highest dose of γ-benzene hexachloride (10 mg/kg). A significant increase in the number as well as the mean area of glutathione S-transferase placental form (GST-P) positive foci, p53 positive hepatocytes, and the percentage of apoptotic cells were observed in the diethylnitrosamine-treated group. In the present investigation, both doses of QC (5 and 25 mg/kg) led to a significant decrease in the number as well as the mean area of GST-P positive foci, TUNEL positive apoptotic cells, p53 positive hepatocytes, and restoration of cellular morphology. These results clearly indicate that quercetin inhibits diethylnitrosamine-induced hepatic preneoplastic lesions in medium-term rat liver bioassay.

Relative influence of testosterone and insulin in the regulation of prostatic cell proliferation and growth

Prostatic hyperplasia is a common problem of the aged men population. Recent experimental and clinical studies provide sufficient evidence that apart from androgens, insulin also plays an important role in the pathogenesis of prostatic hyperplasia. The present study was aimed to investigate the relative influence of testosterone and insulin on the cellular proliferation and prostatic growth. Effect of testosterone on the prostate of hypoinsulinemic, and glandular injection of insulin-receptor antagonist S961 on the prostate of castrated Sprague-Dawley rat (220±10 g) was examined. Significant decrease in the weight of the ventral prostate was observed in the streptozotocin-induced hypoinsulinemic rats (~6 fold), which is restored by the intervention of testosterone. Although, glandular injection of S961 did not led to any change in the frequency of proliferating cell nuclear antigen (PCNA) positive cells in normal rats, significant decrease was observed in the castrated rats. Castration led to increase in the frequency of the caspase-3 and the TUNEL positive cells in the ventral prostate. Further, long-term (6 weeks) administration of S961 induced significant decrease in the weight of the ventral prostate. Results of the present study provide that both testosterone and insulin promote prostatic cell proliferation and change in the level of either of the hormone results in the destabilization of cellular equilibrium, and modulation of the insulin-receptor signaling in the prostate may provide an alternative strategy for the treatment of prostatic enlargement. Further, studies are required to better understand the interplay between these hormones in the regulation of prostatic growth.

Effect of melatonin on the expression of Nrf2 and NF-kappaB during cyclophosphamide-induced urinary bladder injury in rat

Urotoxicity is one of the major problems associated with cyclophosphamide (CP) chemotherapy in cancer patients. Melatonin is a potent antioxidant and reduces CP-induced urotoxicity. However, the molecular mechanisms of protection offered by melatonin are not yet clear. The present study investigated the role of nuclear erythroid 2-related factor 2 (Nrf2) and nuclear factor-kappa B (NF-kappaB) on melatonin-mediated protection against CP-induced urotoxicity. CP was administered intraperitoneally at the dose of 150 mg/kg to induce urotoxicity in male Sprague-Dawley rats. Melatonin treatment (10 mg/kg) was initiated 3 days before and continued for 1 day after the CP administration. Melatonin treatment reduced the CP-induced oxidative stress and DNA damage in the urinary bladder as observed by abrogation in thiobarbituric acid-reactive substances and glutathione levels as well as comet and modified comet assay parameters. Melatonin treatment reduced the bladder damage and apoptosis as observed by histological analysis and TUNEL assay. Melatonin increased the expression of transcription factor Nrf2 as well as associated phase-II enzymes NADPH: quinone oxidoreductase-1 and heme oxygenase-1. Further melatonin treatment reduced the expression of transcription factor NF-kappaB. The results of the present study provide evidence that melatonin treatment favorably alters Nrf2 and NF-kappaB expression and, this appears to be at least in part responsible for observed protection against CP-induced urotoxicity.

Antioxidant and antimutagenic effect of quercetin against DEN induced hepatotoxicity in rat

Diethylnitrosamine (DEN), a potent hepatocarcinogen, is found in tobacco smoke, processed meat as well as in different food products. Quercetin (QC), a naturally occurring flavonoid has excellent antioxidant properties. The present study was aimed to investigate the chemoprotective potential of QC against DEN induced hepatotoxicity in Sprague-Dawley (SD) rats. Quercetin was administered (10, 30 and 100 mg/kg) for 5 consecutive days after DEN (200 mg/kg) treatment. The animals were killed 24 h after the last dose of QC/saline treatment. The DEN induced hepatotoxicity was evident by elevated malondialdehyde (MDA) and decreased glutathione (GSH) levels in the liver. A significant increase in the levels of plasma aspartate transaminase (AST) and plasma alanine transaminase (ALT) was observed in the DEN treated group. The DEN induced DNA damage was evaluated using a single cell gel electrophoresis (SCGE) assay. A significant increase in the number of TUNEL positive cells was observed in the DEN treated group. Quercetin restored AST, ALT and GSH levels at all the tested doses. Restoration of the MDA level and cellular morphology was observed at doses of 10 and 30 mg/kg of QC. Further, DEN induced DNA damage and apoptosis was ameliorated by QC. The results indicate that QC ameliorates the DEN induced hepatotoxicity in rats and can be a candidate for a good chemoprotectant.

Increased cell proliferation and contractility of prostate in insulin resistant rats: linking hyperinsulinemia with benign prostate hyperplasia

BACKGROUND

Obesity, dyslipidemia, Hyperinsulinemia, and insulin resistance (IR) are key features of metabolic syndrome and are considered as risk factors for benign prostatic hyperplasia (BPH) as well as type 2 diabetes. The present study was aimed to determine whether or not IR associated hyperinsulinemia contributes to the BPH.

METHODS

Sprague-Dawley rats (9 weeks) were used in the study. Rats were kept on high fat diet (HFD) for the induction of hyperinsulinemia while hypoinsulinemia was induced by streptozotocin. Effect of HFD feeding on the testosterone-induced prostatic growth was evaluated. Pioglitazone (PG, 20 mg/kg) was used for the reversal of compensatory hyperinsulinemia and to examine the subsequent effect on the prostatic growth.

RESULTS

Prostatic enlargement was observed in the HFD-fed rats. Significant increase in the cell proliferation markers confirmed the occurrence of cellular hyperplasia in the prostate of hyperinsulinemic rat. Enhanced alpha-adrenoceptor mediated contraction in the prostate of HFD-fed rats indicates augmented contractility of the gland. Higher level of phosphorylated-ERK suggests enhanced MEK/ERK signaling. HFD feeding has not led to change in the plasma testosterone level. However, testosterone treatment further augmented the prostatic growth in HFD-fed rats. PG treatment led to improved insulin sensitivity, decreased plasma insulin level and prostate weight, indicating the role of compensatory hyperinsulinemia in the prostate growth.

CONCLUSIONS

The present investigation reports that HFD-feeding induced hyperinsulinemic condition leads to increased cellular proliferation, enhanced alpha-adrenoceptor mediated contraction, and enlargement of the prostate in rats.

Methotrexate-induced cytotoxicity and genotoxicity in germ cells of mice: intervention of folic and folinic acid

Methotrexate (MTX) is an anti-metabolite widely used in the treatment of neoplastic disorders, rheumatoid arthritis and psoriasis. The basis for its therapeutic efficacy is the inhibition of dihydrofolate reductase (DHFR), a key enzyme in the folic acid (FA) metabolism. FA is a water-soluble vitamin which is involved in the synthesis of purines and pyrimidines, the essential precursors of DNA. Folinic acid (FNA) is the reduced form of FA that circumvents the inhibition of DHFR. Folate supplementation during MTX therapy for psoriasis and inflammatory arthritis reduces both toxicity and side effects without compromising the efficacy. Further, FNA supplementation reduces the common side effects of MTX in the treatment of juvenile idiopathic arthritis. FA and FNA are reported to have protective effects on MTX-induced genotoxicity in the somatic cells; however their protective effects on the germ cells have not been much explored. Previously, we evaluated the cytotoxic and genotoxic effects of MTX in the germ cells of mice. In the present study, we have intervened FA and FNA for the protection of germ cell toxicity induced by MTX in male swiss mice. The animals were pre-treated with FA at the doses of 50, 100 and 200 microg/kg for 4 consecutive days per week and on day five; MTX was administered at the dose of 20mg/kg once. FNA was administered at the doses of 2.5, 5 and 10 mg/kg, 6 h (h) after single administration of MTX at the dose of 20 mg/kg. The dosing regimen was continued up to 10 weeks. The germ cell toxicity was evaluated using testes weight (wt), sperm count, sperm head morphology, sperm comet assay, histology, TUNEL and halo assay in testis. The results clearly demonstrate that prior administration of FA and post-treatment with FNA reduces the germ cell toxicity induced by MTX as evident from the decreased sperm head abnormalities, seminiferous tubule damage, sperm DNA damage, TUNEL positive cells and increased sperm counts. In the present study, we report that FA and FNA ameliorate the germ cell toxicity of MTX in mice.

Astaxanthin inhibits cytotoxic and genotoxic effects of cyclophosphamide in mice germ cells

Cyclophosphamide (CP), an alkylating agent used in the treatment of several cancers as well as an immunosuppressant in rheumatoid arthritis. It is used against several cancers due to its broad spectrum efficacy, but at the same time possesses unwanted risks for occupational exposure as well as therapy related toxicities to patients. The present study was aimed to investigate the protective effect of astaxanthin (AST) a red carotenoid pigment on CP induced germ cell toxicity in male mice. CP was administered intraperitoneally (i.p.) at the dose of 50, 100 and 200mg/kg body weight to mice (20-25 g) once in a week for a period of five weeks. AST was given at the dose of 25mg/kg per oral (p.o.) for five consecutive days in a week for five weeks. The animals were sacrificed one week after the last injection of CP. The protective effect of AST against CP induced male germ cell toxicity was evaluated using body weight, testes and epididymis weight, sperm count, sperm head morphology, sperm comet assay, histology of testes and TUNEL assay. AST treatment significantly improved the testes weight, sperm count and sperm head morphology as compared to only CP treated animals. The result of comet assay showed that AST treatment significantly restored the sperm DNA damage induced by CP. Further, AST treatment showed protection against CP induced testicular toxicity as evident from testes histology and TUNEL assay. The present results indicate the chemoprotective potential of AST against CP induced germ cell toxicity in mice.

Use of the alkaline comet assay for the detection of transplacental genotoxins in newborn mice

Several lines of evidence show that in utero exposure to different toxicants has greater consequences than their exposure during adult life. This may be due to involvement of critical developmental stages, physiological immaturity and the long later-life span over which disease may initiate, develop and progress. The in vivo alkaline comet (single-cell gel electrophoresis) assay has been favoured by the scientific community for the evaluation of genotoxins. The objective of this study was to demonstrate the suitability of alkaline comet assay in detecting transplacental genotoxins using newborn mice. Here, we report the successful use of the comet assay in detecting multi-organ genotoxicity of known transplacental genotoxins in newborn mice. Three well known transplacental genotoxic agents, cyclophosphamide (CP), mitomycin-C (MMC) and zidovudine (AZT) were tested in pregnant Swiss mice. These compounds were administered in the late gestational period (16-20th days of pregnancy) and the comet assay was performed with lymphocytes, bone marrow, liver and kidney cells of newborn mice. Significant DNA damage was observed in all the tissues with tested transplacental genotoxins. The results of the comet assay were confirmed by the micronucleus (MN) assay of the peripheral blood of newborn mice. The results of this study provide sufficient evidence that the comet assay can be applied successfully for the detection of transplacental genotoxins in newborn mice.

Protective effect of a polyherbal formulation (Immu-21) against cyclophosphamide-induced mutagenicity in mice

The object was to evaluate the effects of a polyherbal formulation, Immu-21, against cyclophosphamide (CP)-induced chromosomal aberrations (CA) and micronuclei (MN) in mice. CP alone (40 mg/kg, i.p.) produced classical as well as non-classical chromosomal aberrations in mice, and the incidence of CA was significantly more in the CP treated group when compared with that of the control group. Immu-21, which contains extracts of Ocimum sanctum, Withania somnifera, Emblica officinalis and Tinospora cordifolia, was given at 100 mg/kg, daily, over 7 days, and 30 mg/kg daily over 14 days and inhibited both CP-induced classical and non-classical chromosomal aberrations ( approximately 40%-60% of control). A significant increase in MN was also observed in bone marrow erythrocytes of mice treated with CP, and pretreatment with Immu-21 also significantly reduced these. Cytotoxicity was evaluated by estimating the ratio of polychromatic erythrocytes (PCEs) to normochromatic erythrocytes (NCEs). The present results indicate that chronic treatment with Immu-21 prevented CP-induced genotoxicity in mice.

Cell proliferation and natural killer cell activity by polyherbal formulation, Immu-21 in mice

Immunomodulatory activity of an Ayurvedic polyherbal formulation, Immu-21 containing extracts of Ocimum sanctum, Withania somnifera, Emblica officinalis and Tinospora cordifolia was studied on proliferative response of splenic leukocytes to T cell mitogens, concanavalin (Con)-A and phytohemagglutinin (PHA) and B cell mitogen, lipopolysaccharide (LPS) in vitro by [3H]-thymidine uptake assay in mice. The cytotoxic activity of Immu-21 was tested by measuring the splenic leukocyte natural killer (NK) cell activity against K 562 cells. Intraperitoneal (i.p.) treatment with Immu-21 (30 mg/kg) once a day for 14 and 21 days did not cause change in body weight and spleen weight, where as splenocytes/spleen count was increased. Treatment of Immu-21 (30 mg/kg, i.p.) for 14 days and 1 mg/kg for 21 days significantly increased LPS induced leukocyte proliferation. NK cell activity was significantly increased when mice were pretreated with Immu-21 (10 and 30 mg/kg, i.p.) once a day for 7 days. The results indicate that pretreatment with Immu-21 selectively increased the proliferation of splenic leukocyte to B cell mitogen, LPS and cytotoxic activity against K 562 cells in mice.

The evaluation of clastogenic potential of trichloroacetic acid (TCA) in chick in vivo test system

The objective of the present study was to evaluate the genotoxic potential of trichloroacetic acid (TCA) in chick bone marrow chromosomes, and the experiment was designed to study the dose, route, time and acute vs. sub-acute (fractionated) yield effects of the chemical. TCA induced chromosomal aberrations in a dose, route and time response manner. The results revealed the genotoxic property of TCA in the tested system.

Clastogenic effects of copper sulphate in chick in vivo test system

The clastogenic potential of copper sulphate was evaluated in chicks, employing chromosome aberration (CA) and micronucleus test (MNT) assays. For CA dose, route, time-response and acute vs. subacute studies have been done while only route and dose-response studies were done for MNT. Three different doses were administered intraperitoneally, and only the highest dose was administered per oral. Neonatal chicks were killed after different time intervals. One-fifth of the highest dose was injected repeatedly with a gap of 24 h in-between for sub-acute regimen. A statistically significant (p<0.05) increase of CA was observed by the two higher doses in i.p. route and by the highest dose in p.o. route. In time-response studies, significant (P<0.05) results were obtained after 24 and 48 h of exposures. A significant increase in micronucleus counts was also observed with the two higher doses in both bone marrow and peripheral blood erythrocytes by the i.p. route and only by the highest dose in bone marrow erythrocytes by the p.o. route. The present results reveal the genotoxic potential of CuSO4 in chick in vivo.

Use of chick, Gallus domesticus, as an in vivo model for the study of chromosome aberration: a study with mitomycin C and probable location of a 'hot spot'

A model bone marrow chromosome aberration test using the chick, Gallus domesticus, is described. The well known reference mutagen mitomycin C was used as the test chemical. Bone marrow chromosomal preparations were investigated after acute (0.5, 1.0, 2.0, 3.5 and 5.0 mg/kg b.w.) doses for dose-response and sub-acute (0.4 mg/kg/day, 5 days) doses for chronic studies. Only a single dose (2 mg/kg b.w.) was employed for time-response (6, 24 and 48 h) and route-response (i.p. and p.o.) studies. All the treated results differed significantly from the respective control value. The present results also revealed the location of a 'hot spot' in chromosome 4. The test is less expensive, more sensitive and reliable and easier than mouse model. This chick mutagenicity test model can be used as an alternative in vivo system for testing the mutagenicity of environmental pollutants.

Evaluation of genotoxicity of a technical grade organophosphate insecticide, Tafethion (ethion), in chicks

The genotoxicity of a technical grade organophosphate insecticide, Tafethion (ethion), was evaluated in a chick in vivo test system employing the chromosome aberration assay (CA). Chicks in their neonatal life period are particularly susceptible to environmental contaminants due to the high rate of cell proliferation and ongoing process of development. This provides a new methodology to screen the genotoxic effect of environmental pollutants. The chemical was tested for three different doses (20, 15 and 10 mg/kg b.w.), in two routes of administration (i.p. and p.o.), after three different durations of acute exposure (6, 24 and 48 h) as well as chronic exposure (4 mg/kg day for 5 days), for the induction of chromosomal aberrations. Mitomycin C was used as the positive control. In general, the chemical induced higher frequencies of chromosomal aberrations than the controls, indicating the genotoxic property of the chemical in the tested system.

Mutagenicity of an organophosphate insecticide acephate--an in vivo study in chicks

The chromosome aberration assay (CA) in bone marrow cells and the micronucleus test (MNT) in both bone marrow and peripheral blood erythrocytes have been carried out for the evaluation of the clastogenic potential of acephate (asataf) in a chick in vivo test system. Technical grade acephate was administered to evaluate dose-responses (25, 50 and 100 mg/kg), route-responses (i.p. and p.o.) and time-responses (6, 24 and 48 h). A comparison of CA frequencies after acute and chronic dosing was also performed. Only 50 mg/kg of acephate induced significant bone marrow chromosome aberrations after 24 h exposure while all three doses induced significant increases in micronuclei in both bone marrow and peripheral blood erythrocytes in i.p. route only. The presented data confirm our earlier reports that the neonatal chicken test system is a convenient model and can be used as an alternative to mammalian systems for screening some environmental contaminants for genotoxicity.

Studies on the genotoxicity of monocrotophos, an organophosphate insecticide, in the chick in vivo test system

The mutagenic potential of an organophosphate pesticide, monocrotophos, was evaluated in the chick in vivo system using the chromosome aberration (CA) assay in bone marrow cells and the micronucleus test (MNT) in both bone marrow and peripheral blood erythrocytes. A significant induction of chromosome aberrations was observed only after 24 h of exposure with the highest dose (5 mg/kg). In general, monocrotophos induced a significantly higher incidence of micronuclei in bone marrow and peripheral blood erythrocytes over controls. From the present results it is concluded that monocrotophos is genotoxic in this in vivo test system. It is further concluded that the neonatal chick in vivo system provides new methodology for screening xenobiotics for mutagenicity.

Genotoxic potential of the organochlorine insecticide lindane (gamma-BHC): an in vivo study in chicks

The purpose of this work was to evaluate the genotoxic potential of lindane (gamma-isomer of benzene hexachloride (BHC)) in chicken in vivo tests: the bone marrow chromosome aberration and micronucleus tests. With the highest dose (100 mg/kg) a significant enhancement of chromosome aberrations was noticed after 24 and 48 h and with the second highest dose (75 mg/kg) after 24 h. A significant increase in the incidence of micronuclei in bone marrow cells was induced by all three doses (100, 75 and 50 mg/kg) given either intraperitoneally or orally while in peripheral erythrocytes only the two higher intraperitoneal doses (100 and 75 mg/kg) gave significant increases. On the basis of these results, lindane may be considered genotoxic in this test system and it is suggested that the chick in vivo system may be used as an alternative to a mammalian system for screening environmental chemicals for genotoxicity.

Thirty day genotoxicity study of an organophosphate insecticide, monocrotophos, in a chick in vivo test system

The genotoxicity of an organophosphate insecticide, monocrotophos, was evaluated upon chronic exposure in a chick in vivo test system employing micronucleus bioassay. In this study the animals were treated once daily for 30 days. The induced frequency of micronuclei in the erythrocytes of both bone marrow (BM) and peripheral blood (PB) were significantly higher than the respective control values. Weekly recording of the body weight of treated and control groups did not reveal any significant effect of the chemical on the general growth rate. The present results revealed the genotoxic potential of monocrotophos and also substantiate our earlier suggestion regarding the suitability of the chick in vivo test system to screen environmental abuses for mutagenicity.