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.

Diethylnitrosamine and thioacetamide-induced hepatic damage and early carcinogenesis in rats: Role of Nrf2 activator dimethyl fumarate and NLRP3 inhibitor glibenclamide.

Two-stage rat hepatocarcinogenesis model was used to induce early carcinogenesis in which thioacetamide (TAA) promotes diethylnitrosamine (DEN) initiated carcinogenesis. Dimethyl fumarate (DMF) used to treat multiple sclerosis, activates the nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant responsive element (ARE) pathway during oxidative stress, and maintains antioxidant levels. Glibenclamide (GLB), a sulphonylurea drug used to treat type II diabetes, possesses anti-inflammatory properties and inhibits NLRP3 inflammasomes. The present study was designed to investigate the concurrent intervention of DMF and GLB on DEN + TAA-induced early hepatic carcinogenesis. DMF and GLB treatment improved DEN + TAA-induced decrease in body weight, increase in liver weight and plasma transaminases, histopathological alterations, DNA damage, and apoptosis. DMF and GLB intervention significantly ameliorated the DEN + TAA-induced alterations in the antioxidant (Nrf2, HO-1, SOD-1, catalase), inflammatory (NF-κB, NLRP3, ASC, caspase-1), fibrogenic (TGF-ß1, collagen) and regenerative proliferative stress (GST-p, HGF, c-MET, TGFα, EGF, AFP) markers. The present results indicate that Nrf2/ARE activation and NLRP3 inhibition might be a rational approach to attenuate oxidative stress and chronic inflammation associated progression of hepatocarcinogenesis.

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.

Methotrexate-induced germ cell toxicity and the important role of zinc and SOD1: Investigation of molecular mechanisms.

Zinc (Zn) was proved to be a germ cell protectant against various disease conditions and toxic insults. Besides other mechanisms, here we have explored the important role of Zn and Zn-dependent SOD1in methotrexate (MTX)-induced germ cell damage. MTX was given 5 mg/kg i.p. once a week for four consecutive weeks, while Zn was supplemented daily at the doses of 3 and 6 mg/kg i.p. for four consecutive weeks. After four weeks of treatment the animals were sacrificed and observed for various end points. There were several histopahtological alterations in the testes like desquamation and altered tubular structures. DNA damage was also increased by MTX as evident by TUNEL assay. Sperm head abnormalities were increased in case of MTX treated animals. Protein expressions of PCNA, BCl-2/Bax, SOD, catalase and GPX5 were found to be altered by the MTX treatment. To further investigate the role of Zn and Zn-dependent SOD1, rats were injected intratesticularly with diethyldithiocarbamate (DEDTC) for three days after MTX 20 mg/kg i.p. was given on the first day. DEDTC in combination with MTX was found to significantly decrease the protein expressions of SOD1, catalase, Nrf2 and GPX4, along with deranged histology. This study adds to the point that Zn might be a better germ cell protectant and deserve further investigation.

Melatonin modulated autophagy and Nrf2 signaling pathways in mice with colitis-associated colon carcinogenesis.

Colon carcinogenesis is long known to be associated with ulcerative colitis (UC), a chronic gastrointestinal disorder. Various pre-clinical and clinical studies have shown that melatonin (MEL) has beneficial effects in cancer. However, elucidation of the detailed molecular mechanisms involved in MEL-mediated protection against the colon carcinogenesis deserves further investigation. The present study was aimed at deciphering the effect of MEL on autophagy and Nrf2 signaling pathways in a mouse model of colitis-associated colon carcinogenesis (CACC). For the induction of CACC, male Swiss Albino mice were administered a single ip injection of 20 mg 1, 2-dimethylhydrazine dihydrochloride (DMH)/kg bw, followed by 3 cycles of 3% w/v dextran sulfate sodium (DSS) in drinking water treatment initiated 1 wk after DMH injection. One week after the initiation of DSS treatment, MEL was administered at the dose of 1 mg/kg, bw, po for 8 and 18 wk. Mice were sacrificed at 10 and 20 wk after DMH injection. MEL treatment decreased the progression of CACC by down regulating the process of autophagy as revealed by the expression pattern of various autophagy markers such as Beclin-1, LC3B-II/LC3B-I ratio and p62. These findings were accompanied with the increased expression of Nrf2 and the associated antioxidant enzymes, NAD(P)H: quinone oxidoreductase (NQO-1) and heme oxygenase-1 (HO-1) in the colon of mice with CACC. MEL intervention reduced autophagy by ameliorating inflammation and oxidative stress in the colon of mice with CACC. We conclude that MEL treatment attenuates the progression of CACC in mice by modulating autophagy and Nrf2 signaling pathways.

Mechanistic insight into beta-carotene-mediated protection against ulcerative colitis-associated local and systemic damage in mice.

PURPOSE: Ulcerative colitis (UC), a chronic gastrointestinal disorder, is a debilitating disease affecting many people across the globe. Research suggests that the levels of several antioxidants, including ß-carotene (ß-CAR), decrease in the serum of patients with UC. The present study was aimed at elucidating the molecular mechanisms involved in ß-CAR-mediated protection against UC in mice. METHODS: UC was induced in mice using 3%w/v dextran sulfate sodium in drinking water for two cycles; one cycle comprised of 7 days of dextran sulfate sodium-treated water followed by 14 days of normal drinking water. ß-CAR was administered at the doses of 5, 10 and 20 mg/kg bw/day, po throughout the experiment. The effect of ß-CAR in mice with UC was evaluated using biochemical parameters, histological evaluation, comet and micronucleus assays, immunohistochemistry and Western blot analysis. RESULTS: The results indicated that ß-CAR treatment ameliorated the severity of UC by modulating various molecular targets such as 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, ß-CAR treatment maintained the gut integrity by increasing the expression of a tight junction protein, occludin, which was decreased in the colon of mice with UC. Also ß-CAR treatment significantly reduced UC-associated elevated plasma lipopolysaccharide level, systemic inflammation and genotoxicity. CONCLUSION: ß-CAR ameliorated UC-associated local and systemic damage in mice by acting on multiple targets.

Influence of 3-aminobenzamide, an inhibitor of poly(ADP-ribose)polymerase, in the evaluation of the genotoxicity of doxorubicin, cyclophosphamide and zidovudine in female mice.

Testing new chemical entities for genotoxicity is an integral part of the preclinical drug-development process. Lowering the detection limit and enhancing the sensitivity of genotoxicity assays is required, as the standard test-battery fails to detect some carcinogens (non-genotoxic) and weak genotoxins. One of the mechanisms that affect the detection of weak genotoxins is related with the DNA-repair efficiency of the cell system used. In the present study, 3-aminobenzamide (3-AB, 30 mg/kg body-weight), a poly(ADP-ribose)polymerase inhibitor, was used to evaluate the DNA-damaging potential of zidovudine (AZT, 400 mg/kg bw), doxorubicin (DOX, 5 mg/kg bw) and cyclophosphamide (CP, 50 mg/kg bw, as a positive control) and sucrose (SUC, 3 g/kg bw, as a negative control) in Swiss female mice. The endpoints considered included micronucleus formation, DNA breakage (in peripheral blood lymphocytes, bone marrow and liver; comet assay) and chromosome aberrations, as well as immunohistochemistry of PARP-1 and phosphorylated histone H2AX (γ-H2AX). The results clearly indicate that the genotoxicity of zidovudine (AZT), doxorubicin (DOX) and cyclophosphamide (CP) was significantly increased in the combination treatments (3-AB+AZT, 3-AB+DOX, 3-AB+CP) as compared with the respective controls (treatment with AZT, DOX and CP alone). There was no increase in the genotoxicity per se after treatment with SUC, 3-AB or 3-AB+SUC, compared with the control (saline). Correlation analysis suggests that all genotoxicity parameters are well correlated with each other. The results clearly show that the genotoxicity of weak genotoxins can be enhanced and detected in the presence of 3-AB in mice. Thus, this approach can be used in the pre-clinical genotoxicity screening of weak genotoxins.

Pre-pubertal exposure of cytarabine-induced testicular atrophy, impaired spermatogenesis and germ cell DNA damage in SD rats.

CONTEXT: Cytarabine (Ara-C) is an effective chemotherapeutic drug for the treatment of acute leukaemias. It inhibits the DNA synthesis and repair, thereby causes cytotoxicity in the proliferating cells. OBJECTIVE: This study was aimed to investigate the effects of pre-pubertal exposure of Ara-C on testesticular development in juvenile SD rats and their function at puberty. MATERIALS AND METHODS: Ara-C was injected at the doses of 50, 100 and 200 mg/kg/day from postnatal day (PND) 29-42 (14 days) by intraperitoneal (i.p.) route. Half of the animals were sacrificed on PND 43 and remaining on PND 70. End points of the evaluation included gross pathological examination, histomorphometric analysis, sperm count and sperm head morphology, cell proliferation and DNA damage as well as apoptosis analysis. RESULTS: Ara-C treatment significantly decreased food and water intake, weight gain, testes and epididymis weight and increased histological alterations in the seminiferous tubule. Furthermore, Ara-C treatment significantly decreased the PCNA-positive cells and sperm count in a dose-dependent manner. Ara-C treatment also increased the DNA damage and apoptosis in testes and sperm as evident from the comet and TUNEL assays results. DISCUSSION: The present study results clearly indicated that Ara-C treatment impaired spermatogenesis and adversely affects the testicular development and its function in rats by reducing the germ cell proliferation and the inducing DNA damage and apoptosis.

Dextran sulfate sodium-induced ulcerative colitis leads to testicular toxicity in mice: Role of inflammation, oxidative stress and DNA damage.

Ulcerative colitis is associated with an alteration in gonadal hormones and affects testicular weight in rodents. However, association of ulcerative colitis with testicular damage is not clearly known. Ulcerative colitis was induced using 5% (w/v) dextran sulfate sodium in normal drinking water for 1, 7-day cycle in short-term study and 2.5% (w/v) dextran sulfate sodium in normal drinking water for 4 cycles with 2 weeks remission period between each cycle in long-term study. Ulcerative colitis was associated with a significant increase in inflammation, oxidative stress, DNA damage in testes and sperm DNA damage and a significant decrease in the epididymal sperm count and 3ß-HSD expression. No difference was observed in the plasma testosterone levels between control and treatment groups. In the present study, ulcerative colitis was associated with testicular damage, and juvenile mice were found to be more sensitive than adult mice.

Effects of nicotine on the testicular toxicity of streptozotocin-induced diabetic rat: intervention of enalapril.

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.

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.

Role of α-lipoic acid in dextran sulfate sodium-induced ulcerative colitis in mice: studies on inflammation, oxidative stress, DNA damage and fibrosis.

Ulcerative colitis affects many people worldwide. Inflammation and oxidative stress play a vital role in its pathogenesis. Previously, we reported that ulcerative colitis leads to systemic genotoxicity in mice. The present study was aimed at elucidating the role of α-lipoic acid in ulcerative colitis-associated local and systemic damage in mice. Experimental colitis was induced using 3%w/v dextran sulfate sodium in drinking water for 2 cycles. α-Lipoic acid was administered in a co-treatment (20, 40, 80 mg/kg bw) and post-treatment (80 mg/kg bw) schedule. Various biochemical parameters, histological evaluation, comet and micronucleus assays, immunohistochemistry and western blot analysis were employed to evaluate the effect of α-lipoic acid in mice with ulcerative colitis. The protective effect of α-lipoic acid was mediated through the modulation of nuclear factor kappa B, cyclooxygenase-2, interleukin 17, signal transducer and activator of transcription 3, nuclear erythroid 2-related factor 2, NADPH: quinone oxidoreductase-1, matrix metalloproteinase-9 and connective tissue growth factor. Further, ulcerative colitis led to an increased gut permeability, plasma lipopolysaccharide level, systemic inflammation and genotoxicity in mice, which was reduced with α-lipoic acid treatment. The present study identifies the underlying mechanisms involved in α-lipoic acid-mediated protection against ulcerative colitis and the associated systemic damage in mice.

Telmisartan ameliorates germ cell toxicity in the STZ-induced diabetic rat: studies on possible molecular mechanisms.

Testicular damage is a common clinical problem in diabetic individuals that severely affects the quality of life. The present study investigates the possible protective mechanisms of telmisartan, an angiotensin II-receptor antagonist in the germ cell of diabetic rat. Male SD rats were used and randomized into six groups: control, telmisartan control, diabetic control and diabetic group treated with telmisartan at the doses of 3, 6 and 12mg/kg/day, per oral for 4 weeks. Diabetes was induced by injecting a single dose of streptozotocin (STZ), (55mg/kg) dissolved in ice-cold 10mM citrate buffer; pH 4.4 and administered i.p. immediately after preparation to the SD rats. At the end of the study, rats were sacrificed and the levels of nitrite, superoxide, malondialdehyde (MDA), glutathione (reduced and peroxidase) and superoxide dismutase (SOD) were measured. Germ cell toxicity was evaluated by using sperm count, sperm comet assay, histology of testes and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. Further to confirm the oxidative and nitrosative damage, immunohistological quantification of 8-oxo-dG (8-oxo-7,8-dihydro-2'-deoxyguanosine) and 3-nitrotyrosine were evaluated respectively. Results showed that telmisartan significantly restored the levels of nitrite, superoxide, malondialdehyde, and glutathione and superoxide dismutase in diabetic testes. Further, telmisartan significantly increased the sperm counts, reduced apoptotic cell death, sperm DNA damage, oxidative and nitrosative damage in diabetic rat. Western blot analysis showed that telmisartan reduced the testicular inflammation and cell death by down-regulating the expression of NF-κB, IL-6, TNF-α, p-ERK1/2, iNOS, caspase-3 and increasing the PPAR-γ expression. Results clearly indicate that telmisartan significantly reduced the both oxidative and nitrosative stress, inflammation and cell death in diabetic testes. The present results confirmed that telmisartan exhibited beneficial role in the germ cell of diabetic rat.

Protective role of atorvastatin against doxorubicin-induced cardiotoxicity and testicular toxicity in mice.

Doxorubicin (DOX), a potent chemotherapeutic agent, is widely used for the treatment of various malignancies. However, its clinical uses are limited due to its dose-dependent adverse effects particularly cardiac and testicular toxicities. DOX-induced toxicity is mainly due to the induction of oxidative stress. Atorvastatin (ATV), a 3-hydroxy 3-methyl glutaryl coenzyme A reductase inhibitor, with lipid-lowering activity, acts as an antioxidant at lower doses. It possesses pleiotropic effects independent of cholesterol-lowering property usually shown at lower doses, which include antioxidant and anti-inflammatory activities. The present study was aimed to investigate the possible protection exerted by atorvastatin against oxidative stress and DNA damage induced by DOX in the heart and testes of mice. The protective role of ATV in the heart and testes of DOX-treated mice was evident from the amelioration of oxidative stress, DNA and cellular damage. The present study clearly indicates that ATV offers a significant protection against DOX-induced oxidative stress and DNA damage in the heart and testes of 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.

Cardioprotective effects of hesperetin against doxorubicin-induced oxidative stress and DNA damage in rat.

Doxorubicin is a widely used chemotherapeutic agent; however, its clinical uses are limited due to its cardiotoxicity associated with an induction of oxidative stress. This study was aimed to investigate the protective effect of hesperetin against doxorubicin-induced cardiotoxicity in rats. Doxorubicin was administered at the dosage of 4 mg/kg bw/week, ip for a period of 5 consecutive weeks. Hesperetin was administered at the dosages of 25, 50 and 100 mg/kg bw, po by gavage for 5 consecutive days in a week for 5 weeks. The animals were killed 1 week after the last injection of doxorubicin. Hesperetin at the doses of 50 and 100 mg/kg bw significantly reduced MDA and increased GSH levels in the doxorubicin-treated animals. Further, hesperetin significantly reduced doxorubicin-induced DNA damage as well as apoptosis at 25, 50, and 100 mg/kg bw as evident from the comet and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assays, respectively. Thus, hesperetin ameliorated doxorubicin-induced cardiotoxicity by reducing oxidative stress, abnormal cellular morphology and DNA damage in rat. Moreover, nuclear factor-kappa B, p38, and caspase-3 play a role in the hesperetin-mediated protection against doxorubicin-induced cardiotoxicity. This study indicates the protective effect of hesperetin against doxorubicin-induced cardiotoxicity.

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.

Simultaneous use of erythropoietin and prior bleeding enhances the sensitivity of the peripheral blood micronucleus assay.

Adult rats are generally not considered as a suitable model for the peripheral blood micronucleus (PBMN) assay in regulatory consideration, owing to the splenic removal of the micronucleated cells from circulation. Although prior bleeding (PrB) increases the sensitivity of the PBMN assay in young rats, the volume of bleeding and the associated stress caused are major concerns for its possible use in genotoxicity studies. The present study was aimed to overcome these limitations in using pre-bled young rats in genotoxicity studies. The bleeding volume was reduced by the simultaneous use of erythropoietin (EPO) to increase the sensitivity of PBMN assay. Young Sprague-Dawley (SD, 26 days) rats were used in the study. The kinetics of RETs-to-ERTs ratio was determined in response to EPO (10-3000 IU/kg) or PrB (0.1-1.0 ml) at different time points (0, 6, 12, 24, 36, 48, 72 and 96 h). Injection of EPO (30 IU/kg) and PrB (0.5 ml) led to a significant increase in the MN frequency in the PBMN assay in response to cyclophosphamide and zidovudine. The effect of EPO treatment and/or PrB on cell viability and proliferation in the bone marrow (BM) was examined. The results of the present study clearly demonstrate that the simultaneous use of both EPO and PrB enhances the sensitivity of the PBMN assay in young rats due to increased cellular proliferation in the BM. This may provide a useful experimental model for the evaluation of marginally active genotoxicants.