Glutathione supplementation improves oxidative damage in experimental colitis

BACKGROUND: The pathogenesis of inflammatory bowel disease is due, in part, to enhanced free-radical production and reduced antioxidant potential in mucosa cells. AIM: We evaluated in a rat model of trinitrobenzensulphonic acid (TNBS) colitis to see whether parenteral administration of glutathione is able to improve mucosal oxidative damage at onset (study A) and during chronic phases of colitis (study B). METHODS: In study A, the rats were injected with a single dose of glutathione (200 mg/kg, i.p.) or saline (0,2 ml, i.p.) 1 h before colitis induction and killed 1 h later. In study B, rats with induced colitis were treated with daily injection of glutathione (50 mg/kg, i.p.) or saline (0,2 ml, i.p.), and killed at 1, 2, 4 and 8 weeks. We evaluated on mucosal samples the macroscopic and histological damage and the oxidative stress assessed by the mucosal levels of lipoperoxides, malonyldialdehyde, glutathione and cysteine. RESULTS: In study A, colitis induction caused a significant increase to the total histological score (p<0.05), lipoperoxide and malonyldialdehyde levels (p<0.001), but did not affect glutathione and cysteine content. Glutathione pre-treatment decreased both total histological score (p<0.05) and lipoperoxide and malonyldialdehyde values (p<0.001). In study B, the extensive macroscopic and histological colonic damage induced by TNBS was accompanied by a reduction of glutathione and cysteine mucosal levels (p<0.01) and increased lipid peroxidation. Glutathione supplementation significantly improved colonic damage (p<0.01), restored glutathione and cysteine levels, and decreased, and even, if not totally, abolished lipid peroxidation (p<0.001). CONCLUSION: This paper further supports the pathogenic role of the imbalance in oxidant/antioxidant content in inducing mucosal colonic damage.     

Evidence of oxidative stress in chronic heart failure in humans

Chronic heart failure (CHF) due to coronary artery disease (CAD)has been shown to be associated with increased plasma thiobarbituricreactive substances (TBARS) and reduced plasma thiol (PSH) concentrations,suggesting oxidative stress (OS). The aims of the present studieswere (a) to determine whether OS is due to CAD or CHF per seand (b) to determine if a wider range of more specific markersof OS are abnormal in CHF. In the first study, two groups of patients (n = 15 each) werecompared. Group 1 (11 male, mean age 56 years) had CHF due toCAD and group 2 (12 male, mean age 53 years) had non-CAD CHF.Median plasma TBARS in controls was 7.6 nmol . ml^–1 ,10.0 nmol . m^–1 in group 1 and 9.3 nmol. ml^–1 ingroup 2 (P < 0.01 both groups vs control). Median PSH was505 384 and 364 nmol. ml^–1 (P < 0.05 and P < 0.01vs control) respectively. Fifty-three patients with CHF were recruited in the second study.Malondialdehyde and PSH were 10.3 and 409 nmol. ml^–1 respectively,compared to control values of 7.9 and 560 nmol. ml^.1 (both P< 0.001). The median values for the following additionalmeasures of OS in controls and patients were: erythrocyte superoxidedismustase 131 vs 114 U . l^–1 (P = 0.005); caeruloplasminoxidase 97 vs 197 U. l^–1 (P < 0.01); erythrocyte glutathione1.56 nmol . ml^–1 vs 1.77 nmol . ml^–1 (P < 0.02);plasma conjugated dienes 0.28 vs 0.33 optical density units(P = ns). Chronic heart failure, regardless of aetiology, is associatedwith abnormalities of a range of markers of OS.     

Esophagitis in sprague-dawley rats is mediated by free radicals

Free radical-mediated esophagitis was studied during duodenogastroesophageal reflux (mixed reflux) or acid reflux in rats. The influence of reflux on esophageal glutathione levels was also examined. Mixed reflux caused more gross mucosal injury than acid reflux. Gross mucosal injury occurred in the mid-esophagus. Total glutathione (GSH) in the esophageal mucosa of control rats was highest in the distal esophagus. The time course of esophageal GSH in rats treated by mixed reflux showed a significant decrease 4 hr after initiation of reflux, followed by a significant increase from the 12th hour on. Mucosal GSH was increased in both reflux groups after 24 hr but significantly more so in the mixed than in the acid reflux group. The free radical scavenger superoxide dismutase (SOD) prevented esophagitis and was associated with decreased GSH levels. GSH depletion by buthionine sulfoximine (BSO) prevented esophagitis and stimulated SOD production in the esophageal mucosa. It is concluded that gastroesophageal reflux is associated with oxidative stress in the esophageal mucosa. The lower GSH levels in the mid-esophagus may predispose to damage in this area. Duodenogastroesophageal reflux causes more damage than pure acid reflux. Oxidative stress leads to GSH depletion of the esophageal mucosa in the first few hours following damage but then stimulates GSH production. GSH depletion by BSO does not worsen esophagitis since it increases the esophageal SOD concentration.     

解除颈动脉狭窄对慢性低灌注大鼠氧化损伤的影响

目的探讨解除颈动脉狭窄对慢性低灌注大鼠认知功能损伤的影响及其可能机制。方法选择雄性SD大鼠30只,将制模成功大鼠12只随机分为狭窄组和狭窄解除组,每组6只。另选6只大鼠为假手术组。采用分光光度法测定超氧化物歧化酶(SOD)活性和丙二醛的含量。结果与假手术组比较,狭窄组大鼠SOD活性明显下降,丙二醛的含量明显升高,差异有统计学意义(P<0.01);与狭窄组比较,狭窄解除组大鼠SOD活性明显升高,丙二醛含量明显下降,差异有统计学意义(P<0.01)。结论氧化损伤参与了重度颈动脉狭窄所致认知功能障碍的作用机制;且解除颈动脉狭窄改善认知功能障碍的作用机制可能与改善脑血流、抗氧化作用有关。     

奥曲肽与丹参多酚酸盐合用对急性胰腺炎大鼠氧自由基影响的研究

[目的]探讨奥曲肽与丹参多酚酸盐合用对急性胰腺炎(AP)大鼠氧自由基的影响.[方法]SD大鼠75只,随机分为5组,每组15只.通过胰胆管逆行性注射牛磺胆酸钠制成AP大鼠模型.分别观察各实验组血清超氧化歧化酶(SOD)、丙二醛(MDA)的变化.[结果]①AP组与假手术组相比,血清SOD水平明显降低(P＜0.05),血清MDA水平明显升高(P＜0.05).②奥曲肽治疗组、丹参多酚酸盐治疗组及奥曲肽、丹参多酚酸盐合用组与AP组相比,血清SOD水平明显升高(P＜0.05),血清MDA水平明显降低(P＜0.05).③奥曲肽、丹参多酚酸盐合用组与奥曲肽、丹参多酚酸盐单用组相比,血清SOD水平明显升高(P＜0.05),血清MDA水平明显降低(P＜0.05).[结论]奥曲肽、丹参多酚酸盐通过升高SOD(保护性因素)、降低MDA(损伤性因素),对AP有明显治疗作用,且奥曲肽、丹参多酚酸盐合用效果更显著.     

Zinc sulphate solution enema decreases inflammation in experimental colitis in rats

BACKGROUND: It has been reported that zinc sulphate contributes an anti-inflammatory action in many animal models; however, the impact of zinc in colitis remains unclear. The aim of the present study was to examine the role of zinc sulphate in experimental colitis. METHODS: Colitis was induced by 2,4,6-trinitrobenzenesulphonic acid (TNB) in rats. Beginning at the first day of TNB colitis, the rats were treated with a zinc sulphate enema once daily for 6 days. The rats were examined 8 days later. RESULTS: The TNB induced severe colitis as evidenced by increased mucosal lesion area, mucosal myeloperoxidase (MPO) activity and prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) levels. Six days after the application of the zinc sulphate enema, the mucosal lesion area, MPO activity, PGE2 and LTB4 levels all decreased significantly. Mucosal superoxide dismutase activity remained unchanged after zinc treatments. CONCLUSIONS: Our data suggest that zinc sulphate enemas have an anti-inflammatory action on experimental colitis.     

Free radicals generated by xanthine oxidase-hypoxanthine damage adenylate cyclase and ATPase in gerbil cerebral cortex

The generation of superoxide radicals from xanthine oxidase-hypoxanthine in a particulate fraction of gerbil cerebral cortex influenced the activity of the synaptic enzyme adenylate cyclase, as well as Mn²⁺- and Na⁺,K⁺-sensitive forms of ATPase. Low concentrations of xanthine oxidase actually elevated the sensitivity of adenylate cyclase to GTP, GTP + norepinephrine (NE), and forskolin but not significantly to Mn²⁺. Higher levels of xanthine oxidase elicited a marked inhibition of these responses. The stimulation of adenylate cyclase mechanisms requiring GTP (GTP, forskolin, and NE) was more susceptible than was Mn²⁺, suggesting that the guanine nucleotide stimulatory protein was more vulnerable to free radical attack than the catalytic site of adenylate cyclase. superoxide dismutase (SOD), but not catalase, partially protected the forskolin-sensitive enzyme from the action of xanthine oxidase-hypoxanthine. A combination of SOD plus catalase preserved enzyme responses to forskolin. In comparison, additions of SOD plus mannitol or catalase plus flunarizine were less effective. The sensitivity of the particulate ATPase to Mn²⁺ was more labile to the consequence of superoxide formation than Na⁺, K⁺-ATPase. In this regard the Ca²⁺, Mg²⁺ sensitivity of the enzyme was reduced only to a marginal extent. The findings might be analogous toin vivo data in which cerebral adenylate cyclase and Na⁺, K⁺-ATPase are damaged following postischemic reperfusion in gerbils, a process thought to be mediated by free radicals.     

中药复方清肠汤对大鼠实验性结肠炎的疗效观察

[目的]观察中药复方清肠汤对实验性结肠炎大鼠的治疗效果.[方法]将40只SD大鼠随机分为空白对照组（A组）、模型组（B组）、西药对照组（C组）、中药常规剂量组（D组）、中药大剂量组（E组）和湿热组（F组）,采用乙酸灌肠加葡聚糖硫酸钠自由饮用的方法制作大鼠实验性结肠炎模型,F组再给予高糖高脂饮食喂养并放置高温高湿环境处理以模拟大肠湿热证形成条件,造模同时D、E、F组给予清肠汤灌胃,C组给予柳氮磺嘧啶（SASP）混悬液灌胃,每日2次,治疗7d后再次以乙酸灌肠,各组均连续灌胃14d,治疗前后每日观察记录大鼠体质量、饮食及活动情况,重点观察粪便的性状改变,造模前后检测肛温,对死亡大鼠进行解剖并观察肠道病理改变.治疗结束后对各组大鼠疾病活动指数（DAD、肠黏膜损伤评分及组织病理学评分（HI）进行统计学评价和分析.[结果]与A组相比,造模后各组大鼠DAI评分、肠黏膜损伤评分和HI评分明显上升（P＜0.05）;给药后,D组和F组的DAI评分有明显下降（P＜0.05）,各组肠黏膜损伤评分和HI评分明显降低（P＜0.05）,F组肠道HI评分明显低于D组（P＜0.05）.[结论]清肠汤能改善实验性结肠炎模型大鼠的症状,并且与SASP一样均能使模型大鼠的肠黏膜损伤减轻.而清肠汤对湿热证模型组大鼠肠道病理损伤的改善优于非湿热证模型组,体现了中医辨证论治的优势.     

p53 antibodies, metallothioneins, and oxidative stress markers in chronic ulcerative colitis with dysplasia

AIM:To investigate the role of p53 antibodies (p53Abs),metallothioneins (MTs) and oxidative stress markers in the early detection of dysplasia in chronic ulcerative colitis (UC).METHODS:The study included 30 UC patients,15 without dysplasia (group Ⅱ) and 15 with dysplasia (group Ⅲ),in addition to 15 healthy volunteers (group Ⅰ,control subjects).The enzyme-linked immunosorbent assay technique was used to measure serum p53Abs and MTs,while advanced oxidation protein products (AOPPs),and reduced glutathione (G...     

Melatonin protects against rotenone-induced oxidative stress in a hemiparkinsonian rat model

In the present study, we evaluated the effect of melatonin, a well-known free radical scavenger and neuroprotector, against rotenone-induced oxidative stress in a hemiparkinsonian rat model. The effect of melatonin on glutathione (GSH) depletion caused by unilateral, intranigral infusion of rotenone was investigated employing a spectrofluorimetric procedure. We also studied the effect of melatonin on rotenone-induced changes in the antioxidant enzymes superoxide dismutase (SOD) and catalase in the cytosolic fractions of substantia nigra (SN), employing spectrophotometric procedures. Rotenone-induced hydroxyl radicals (*OH) in the isolated mitochondria, as measured employing a sensitive HPLC-electrochemical method, were significantly scavenged by melatonin. Melatonin treatment restored the rotenone-induced decrease in GSH level and changes in antioxidant enzyme (SOD and catalase) activities in the SN. Our results strongly indicate melatonin's beneficial use in Parkinson's disease therapy as an antioxidant.     

丹参对重症急性胰腺炎早期多器官组织脂质过氧化的影响

[目的]研究丹参对重症急性胰腺炎(SAP)早期多器官组织脂质过氧化的影响及其作用机制.[方法]将30只大鼠随机分为3组,即正常组、模型组和丹参治疗组.采用逆行胰管注射法建立大鼠SAP模型,观察胰、心、肝、肺、肾组织的超氧化物歧化酶(SOD)、丙二醛(MDA)和组织学变化及丹参注射液对其的影响.[结果]模型组的多器官组织MDA增加、SOD活性降低,以胰、心、肝、肾为主;丹参注射液可升高胰、心、肝、肾等组织的SOD活性,降低胰、肝、肾组织的MDA水平.[结论]SAP早期存在着多器官组织脂质过氧化,相应组织中SOD活性的降低是其原因之一.丹参可提高SAP多器官组织SOD活性而减轻组织脂质过氧化,以胰、肝、肾为主.     

Xanthine oxidase-derived oxygen radicals play significant roles in the development of chronic pancreatitis in WBN/Kob rats

BACKGROUND: Although oxygen-derived free radicals are known to play a role in cell injury and DNA alterations, the role of active oxidants in chronic pancreatitis has not been fully elucidated. Using WBN/Kob rats, which spontaneously develop chronic pancreatitis-like lesions, we investigated whether xanthine oxidase (XOD)-derived oxygen radicals are involved in pancreatic tissue injury. METHODS: WBN/Kob rats were fed a control or a tungsten diet. The latter depletes XOD activity. Histologic al changes, glutathione (GSH) content and XOD and superoxide dismutase (SOD) activities were determined in pancreatic tissue. Pancreatic 8-hydroxy-deoxyguanosine (8-OH-dG) levels and lithostathine mRNA were also examined. RESULTS: In WBN/Kob rats, parenchymal destruction and fibrosis developed at approximately 12 weeks of age and progressed with each month. The activity of XOD was significantly higher in the early period (8-12 weeks), whereas the levels of GSH and SOD decreased after 16 weeks. Levels of 8-OH-dG in WBN/Kob rats were significantly elevated at 16 weeks. Lithostathine mRNA levels started to increase at 8 weeks, but were suppressed at 16 weeks. The tungsten diet significantly attenuated the histological changes in WBN/Kob rats. The increase in pancreatic XOD activity and 8-OH-dG content in WBN/Kob rats was significantly inhibited by the tungsten diet and lithostathine mRNA levels remained high at 16 weeks. CONCLUSION: These results suggest that oxygen radicals generated by XOD play an important role in oxidative DNA damage and the development of chronic pancreatic injury.     

Superoxide dismutase in the central nervous system of Torpedo marmorata

In the central nervous system of Torpedo marmorata lipofuscin accumulates electively in the electric lobes. It has been found that the electric lobes have significantly lower superoxide dismutase activity than other areas of the central nervous system in animals of various ages and weights. These observations indicate that the lipoperoxidation action of the superoxide radicals or of their derived free radicals, due to superoxide dismutase deficit in these areas, might be related to lipofuscin accumulation.     

Melatonin ameliorates oxidative organ damage induced by acute intra-abdominal compartment syndrome in rats

Acutely increased intra-abdominal pressure (IAP) can lead to multiple organ failure. As blood flow to intra-abdominal organs is reduced by high venous resistance, ischemia-reperfusion (I/R) injury plays an important role in the pathogenesis of abdominal compartment syndrome (ACS) following IAP. Melatonin, a secretory product of the pineal gland, is known to have free radical scavenging and antioxidative properties in several oxidative processes. The objective of this study was to examine the potential protective properties of melatonin on the oxidative organ damage in a rat model of ACS. Under ketamine anesthesia, an arterial catheter was inserted intraperioneally (i.p.) and using an aneroid manometer connected to the catheter, IAP was kept at 20 mmHg (ischemia group; I) for 1 hr. In the ischemia/reperfusion (I/R) group, pressure applied for an hour was decompressed and a 1-hr reperfusion period was allowed. In another IR group, melatonin was administered (10 mg/kg, i.p.) immediately before the decompression of IAP. The results demonstrate that tissue levels of malondialdehyde (MDA) and myeloperoxidase activity (MPO; index of tissue neutrophil infiltration) were elevated, while glutathione (GSH; a key to antioxidant) levels were reduced in both I and I/R groups (P < 0.05-0.001). Melatonin treatment in I/R rats reversed these changes (P < 0.01-0.001). Moreover, melatonin given to the I/R group reduced the elevations in serum aspartate aminotransferase, alanine aminotransferase and blood urea nitrogen levels and abolished the increase in serum creatinine levels. Our results indicate that melatonin, because of antioxidant and free radical scavenging properties, ameliorates reperfusion-induced oxidative organ damage. In conclusion, the results of the present study suggest that the therapeutic value of melatonin as a 'reperfusion injury-limiting' agent must be considered in ACS.     

Melatonin modulates signal transduction pathways and apoptosis in experimental colitis

Various evidences have documented that the pineal secretory product melatonin exerts an important anti-inflammatory effect in different experimental models including colitis. The aim of the present study was to evaluate whether melatonin regulates the inflammatory response of experimental colitis in rats at the level of signal transduction pathway. Colitis was induced by intracolonic instillation of dinitrobenzene sulfonic acid (DNBS). Four days after DNBS administration, a substantial increase of colon TNF-alpha production was associated with the colon damage. In DNBS-treated rats, the colon injury correlated with a significant rise of apoptosis (evaluated by TUNEL coloration) which was associated with a significant increased expression of proapoptotic Bax and decreased colon content of antiapoptotic Bcl-2. This inflammatory response was also related to activation of nuclear factor-kappaB (NF-kappaB) and phosphorylation of c-Jun as well as FAS ligand expression in the colon. Treatment with melatonin (15 mg/kg daily i.p.) was associated with a remarkable amelioration of colonic disrupted architecture as well as a significant reduction of TNF-alpha. Melatonin also reduced the NF-kappaB activation and phosphorylation of c-Jun as well as the Fas ligand expression in the colon. Furthermore, melatonin reduced the expression of Bax and prevented the loss of Bcl-2 proteins as well as the presence of apoptotic cells caused by DNBS. The results of this study show that melatonin administration exerts beneficial effects in inflammatory bowel disease by modulating signal transduction pathways.     

Effect of cyclosporine in a murine model of experimental colitis

The use of immunosuppressive therapy may be associated with significant toxicity. The aim of this study was to investigate the effect of cyclosporine A (CsA) in murine model of experimental colitis. Experimental colitis was induced in NMRI mice using an enema of 0.2% solution of dinitrofluorobenzene, combined with skin sensitization. After inducing colitis, experimental groups of animals were treated with CsA (1, 3, 5, 10, 25, 50 mg/kg/day) intraperitoneally (i.p.) or intracolonically (i.c.), and control groups were treated with phosphate-buffered saline intraperitoneally or intracolonically, respectively. Colonic inflammatory changes were assessed using a histopathologic score of 0–30, and pooled whole blood samples were processed with monoclonal antibodies for cyclosporine concentration. In addition, two groups of animals with experimental colitis were treated intraperitoneally or intracolonically with 3 mg/kg/day of CsA, and the colons were also taken for immunohistochemistry for CD25. CsA diminished the extent of colitis in groups treated with 3, 5, 10, or 25 mg/kg intraperitoneally or intracolonically, and in groups treated with 1 and 50 mg/kg intracolonically (P < 0.05). The effect of intracolonic application of CsA was not related to whole blood cyclosporine concentrations. In addition, the effect of CsA at 3 mg/kg, applied intraperitoneally or intracolonically was, in part, expressed in decreasing the numbers of CD25+ cells within colonic mucosa/submucosa (P < 0.05). In conclusions, the results of this study indicate the possibility of intracolonic application of cyclosporine in order to widen the therapeutic window for effective, but possibly toxic drug, such as cyclosporine.     

Melatonin inhibits lipid peroxidation and stimulates the antioxidant status of diabetic rats

Although melatonin has been established as a free radical scavenger and antioxidant, its effects in diabetes have not been thoroughly investigated. The purpose of this study, therefore, was to investigate the effects of melatonin administration on lipid peroxidation and antioxidant status in streptozotocin (STZ)-induced diabetes in rats. Concentrations of malondialdehyde (MDA) and reduced glutathione (GSH) in erythrocytes and activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were compared in 3 groups of 10 rats each [control non-diabetic rats (group I), untreated diabetic rats (group II) and diabetic rats treated with melatonin (group III)]. In the study groups, diabetes developed 3 days after intraperitoneal (i.p.) administration of a single 60-mg/kg dose of STZ. Thereafter, while the rats in group II received no treatment, the rats in group III began to receive a 10-mg/kg i.p. dose of melatonin per day. After 6 wk, the rats in groups II and III had significantly lower body weights and significantly higher blood glucose levels than the rats of group I (P<0.001 and P<0.001, respectively). There were no significant differences in body weight or blood glucose levels between groups II and III. MDA levels in untreated diabetic rats were higher than those in control group rats and in diabetic rats treated with melatonin (P<0.01 and P<0.05, respectively). However, MDA levels in diabetic rats treated with melatonin were not different from those of the control group. The GSH, GSH-Px and SOD levels of untreated diabetic rats were significantly lower than those of the control group (P<0.02, P<0.002 and P<0.05, respectively). In group III, however, melatonin prevented decreases in the thiol antioxidant and the associated enzymes, and so these levels were not significantly different from those in the control group. These results confirm the presence of oxidative stress in STZ-induced experimental diabetes and indicate the beneficial free radical-scavenging and antioxidant properties of melatonin.