猴头菌粉与5-氨基水杨酸联用抑制小鼠急性溃疡性结肠炎并提高肠道共生菌Parabacteroides distasonis丰度

猴头菌Hericium erinaceus是一种药食同源真菌,广泛应用于治疗胃肠道疾病,可采用液态发酵技术规模化量产获得菌丝体粉。本研究旨在分析猴头发酵菌粉(HE,300mg/kg/d)与5-氨基水杨酸(5-aminosalicylic acid,5-ASA,150mg/kg/d)联用对葡聚糖硫酸钠(dextran sodium sulfate,DSS)诱导的小鼠结肠炎的治疗作用。HE和5-ASA能够减轻小鼠急性溃疡性结肠炎症状,包括减轻体重的降低率和疾病活动指数评分(DAI)。HE和5-ASA联用可以显著抑制小鼠结肠组织炎症,通过降低肿瘤坏死因子-α(Tnf-α)和白细胞介素-β(Il-β)基因的表达。此外,利用16SrRNA基因测序技术对小鼠盲肠微生物群落组成及结构进行分析。HE与5-ASA联用可以重塑肠道微生态环境,并显著提高狄氏副拟杆菌Parabacteroides distasonis相对丰度。人体粪便体外发酵结果证实HE与5-ASA可以增加P. distasonis。综上,HE与5-ASA联用可有效抑制小鼠结肠炎症水平,并调节肠道微生物,可能是通过增加P. distasonis起作用。     

大黄牡丹汤对实验性结肠炎小鼠血清细胞因子的影响

目的:探讨大黄牡丹汤对TNBS诱导的小鼠实验性结肠炎的治疗作用及作用机理。方法:采用三硝基苯磺酸(TNBS)法制作实验性结肠炎小鼠模型,给予大黄牡丹汤治疗,观察小鼠的一般状态和DAI评分、结肠组织学变化。采用Luminex液相芯片系统检测血清中白介素1β、白介素4和肿瘤坏死因子α的含量。结果:大黄牡丹汤对TNBS结肠炎小鼠的一般状况及DAI评分有改善作用、并能缓解结肠局部的炎症,可降低血清中白介素1β和肿瘤坏死因子α的含量的水平。结论:大黄牡丹汤具有一定地防治TNBS所诱导的小鼠结肠炎的作用,其机制可能与抑制白介素1β和肿瘤坏死因子α的分泌有关。     

整肠生对溃疡性结肠炎 小鼠肠上皮屏障的保护作用

目的探讨整肠生对溃疡性结肠炎小鼠肠道紧密连接蛋白表达以及对氧化应激反应的影响。方法选用雄性8~10周龄C57BL/6小鼠40只,随机分为4组:对照组、模型组(3%DSS)、5-ASA组(3%DSS+5-ASA 200mg/kg灌胃)和整肠生组(3%DSS+联合整肠生及5-ASA灌胃),每组10只,造模7d。观察各组小鼠便血程度、组织学损伤情况,通过投射电镜观察各组肠道上皮间紧密连接改变情况,应用Western blot和RT-PCR的方法,检测小鼠结肠黏膜紧密连接蛋白Occludin、ZO-1、Claudin-2的表达情况。结果 (1)与模型组比较,5-ASA组和整肠生组小鼠便血程度明显减轻,DAI评分显著降低(P0.05)。整肠生组与5-ASA组比较,便血减轻,DAI评分降低(P0.05)。(2)电镜显示,对照组肠上皮间紧密连接呈一条致密条带,结构完整,见细胞桥粒,微绒毛光滑、排列整齐,细胞间隙狭窄;模型组肠上皮间紧密连接结构松散、模糊、密度降低,桥粒结构消失,微绒毛稀疏,短缩且长短不一,细胞间隙增宽;各治疗组的紧密连接的破坏情况较模型组有不同程度的改善,整肠生组紧密连接清晰,细胞间隙缩窄,微绒毛排列整齐,出现细胞桥粒。(3)应用Western blot和Real time-PCR法检测,与正常组相比,模型组Occludin、ZO-1蛋白和mRNA表达显著下降,Claudin-2表达显著上调(P0.05);各治疗组较模型组Occludin、ZO-1蛋白表达上调,Claudin-2蛋白表达下调(P0.05),整肠生组较单用5-ASA组更明显提高Occludin、ZO-1蛋白和mRNA表达。(4)与正常组相比,模型组MDA含量增高,SOD活性降低,与5-ASA组相比,整肠生组能更显著地降低MDA含量,提高SOD活性(P0.05)。结论联合应用整肠生通过调节紧密连接蛋白Occludin、ZO-1的表达和降低氧化应激反应,来改善溃疡性结肠炎小鼠肠上皮屏障功能。     

sIgA在炎症性肠病小鼠肠黏膜中的表达及布拉酵母菌的干预作用

目的建立TNBS小鼠炎症性肠病(IBD)模型,探讨肠道sIgA含量变化与IBD发病的相关性。研究布拉酵母菌(Saccharomyces boulardii,SB)对炎症状态下肠道sIgA调节作用。方法采用随机法将小鼠分成3组:WT组、TNBS组、TNBS+SB组;14d后观察小鼠一般状态,行疾病活动指数(DAI)评分;处死小鼠后收集结肠组织,行形态观察和大体形态损伤评分;HE染色;ELISA法检测肠液中sIgA浓度;免疫组化法和Western blot对结肠组织sIgA蛋白进行定位和定量研究。结果 TNBS组小鼠较WT组腹泻次数增加、体重下降明显,SB干预后症状缓解,体重增加,DAI评分明显下降(P0.01);TNBS组与WT组比较结肠大体损伤评分明显升高(P0.01),SB治疗2周后评分明显下降(P0.01);光镜下TNBS组炎症改变较WT组、TNBS+SB组明显;sIgA主要表达于肠腺腺腔内,肠腺之间以及肠绒毛固有层中;肠液中sIgA浓度水平及结肠组织中sIgA表达,TNBS组较WT组和TNBS+SB组均明显下降(P0.01;P0.01),TNBS+SB组与WT组相比差异无统计学意义(P0.05)。结论 sIgA含量的变化与炎症性肠病的发生有相关性。布拉酵母菌能够上调sIgA水平,说明其可能是通过相应途径促进sIgA表达从而减轻IBD的肠道炎症反应。     

黄芩苷对实验性结肠炎小鼠TLRs/MyD88通路的作用研究

本文研究黄芩苷对葡聚糖硫酸钠(DSS)诱导的结肠炎小鼠模型的疗效,并从TLRs/MyD88通路探讨其作用机制。C57BL/6小鼠24只,分为空白对照组、模型组和黄芩苷组,用3.5%DSS诱导结肠炎模型,黄芩苷(30 mg/kg)干预7天,记录小鼠的疾病活动指数(DAI)评分,HE染色观察病理改变并评分,检测结肠髓过氧化物酶(MPO)活性,ELISA法检测肿瘤坏死因子(TNF)-α和白介素(IL)-6浓度,Real-time PCR法检测TLR2、TLR4和MyD88 mRNA表达水平。结果显示黄芩苷能有效抑制结肠炎小鼠DAI评分、结肠组织病理学评分和MPO活性,降低IL-6和TNF-α表达,降低TLR2、TLR4和MyD88 mRNA的表达。表明黄芩苷能有效缓解DSS诱导的结肠炎小鼠模型的症状,降低炎症反应,其作用机制可能是与TLRs/MyD88通路相关。     

携带IL-10基因的双歧杆菌对溃疡性结肠炎模型小鼠血浆及结肠组织NO和VEGF-A表达影响

目的观察携带IL-10基因的双歧杆菌对溃疡性结肠炎(UC)小鼠血浆及结肠组织一氧化氮(NO)与血管内皮生长因子A(VEGF-A)表达的影响,进一步探讨携带IL-10基因的双歧杆菌治疗UC的相关机制。方法筛选出能稳定表达具有生物活性hIL-10蛋白的BL-hIL-10菌株。用5%DSS诱导UC小鼠模型,50只小鼠分为正常对照组、UC模型组、BL治疗组、BL0治疗组和BL-hIL-10治疗组,每组10只。计算小鼠DAI、HE染色评估结肠组织病理学变化;ELISA法测小鼠血浆及结肠组织IL-13、VEGF-A和NO的含量。结果 (1)BL-hIL-10可以降低UC小鼠DAI,减轻UC小鼠结肠组织炎症程度。(2)BL-hIL-10能降低UC小鼠血浆和结肠组织NO、VEGF-A和IL-13水平。结论口服BL-hIL-10对UC小鼠的治疗作用可能与抑制NO产生及下调VEGF-A表达有关。     

核桃低聚肽对急性溃疡性结肠炎小鼠的改善作用

目的：探讨核桃低聚肽（WOPs）对急性溃疡性结肠炎小鼠的改善作用。方法：成年雄性BALB/C小鼠按体重随机分为6组,空白对照组、模型对照组和3个WOPs剂量组（220、440、880 mg/kg BW）,每组10只。小鼠饮用5%DSS构建急性溃疡性结肠炎模型,灌胃给予相应受试物7 d,每日观察测量DAI。7 d后,处死小鼠测量结肠外观形态及长度变化、CMDI,血清DAO、D-LA含量,结肠组织TNF-α、IL-1β、IL-6、IL-10、MPO含量,并进行结肠组织病理学观察。结果：WOPs能显著减少血清DAO和D-LA含量,降低DAI评分、结肠组织MPO、IL-1β、IL-6、TNF-α水平,提高IL-10水平,明显增加结肠长度,降低CMDI。此外,WOPs还可以恢复DSS所致的结肠黏膜炎症损伤。结论：WOPs对经DSS诱导的溃疡性结肠炎小鼠具有改善作用,其机制可能与调整机体内促炎因子与抗炎因子含量有关。     

猴头菌粉与5-氨基水杨酸联用抑制小鼠急性溃疡性结肠炎并提高肠道共生菌Parabacteroides distasonis丰度

猴头菌Hericium erinaceus是一种药食同源真菌,广泛应用于治疗胃肠道疾病,可采用液态发酵技术规模化量产获得菌丝体粉。本研究旨在分析猴头发酵菌粉（HE,300mg/kg/d）与5-氨基水杨酸（5-aminosalicylic acid,5-ASA,150mg/kg/d）联用对葡聚糖硫酸钠（dextran sodium sulfate,DSS）诱导的小鼠结肠炎的治疗作用。HE和5-ASA能够减轻小鼠急性溃疡性结肠炎症状,包括减轻体重的降低率和疾病活动指数评分（DAI）。HE和5-ASA联用可以显著抑制小鼠结肠组织炎症,通过降低肿瘤坏死因子-α（Tnf-α）和白细胞介素-β（Il-β）基因的表达。此外,利用16S rRNA基因测序技术对小鼠盲肠微生物群落组成及结构进行分析。HE与5-ASA联用可以重塑肠道微生态环境,并显著提高狄氏副拟杆菌Parabacteroides distasonis相对丰度。人体粪便体外发酵结果证实HE与5-ASA可以增加P. distasonis。综上,HE与5-ASA联用可有效抑制小鼠结肠炎症水平,并调节肠道微生物,可能是通过增加P. distasonis起作用。     

罗格列酮对溃疡性结肠炎大鼠的保护作用及机制研究

目的:探讨罗格列酮对溃疡性结肠炎大鼠的保护作用及其作用机制。方法:三硝基苯磺酸(TNBS)/乙醇复合法用于建立大鼠溃疡性结肠炎模型,8周龄健康成年雄性SD大鼠15只,随机分成3组,每组5只,分别为对照组、溃疡组和罗格列酮组。对照组为生理盐水灌肠和灌胃,模型组为TNBS/乙醇混合液灌肠和生理盐水灌胃,罗格列酮组则从灌肠造模成功后的第二天起,每天采用罗格列酮灌胃给药1次(5 mg/kg)。观察大鼠的一般活动状态,并记录各组大鼠的疾病活动指数(DAI),于灌肠后第60天处死大鼠,镜下观察并记录各组大鼠的结肠黏膜损伤指数(CDMI),苏木色精-伊红法(HE)染色后,镜下观察各组大鼠的结肠组织病理学改变,并进行组织学评分(HS)。生化法用于检测大鼠结肠组织中超氧化物歧化酶(SOD)、丙二醛(MDA)和髓过氧化物酶(MPO)的含量。实时荧光定量聚合酶链式反应(qRT-PCR)和免疫组化(IHC)法分别检测各组大鼠结肠组织中过氧化物酶增殖激活受体-γ(PPARγ)、核转录因子_(-κ)B(NFκB)和肿瘤坏死因子-α(TNF-α)的mRNA和蛋白表达水平。结果:与对照组相比,溃疡组的DAI、CDMI和HS评分均显著增加(P0.05);SOD含量显著降低,MDA和MPO的含量显著增加(P0.05);PPARγ的mRNA和蛋白表达量显著降低(P0.05);NFκB和TNF-α的mRNA和蛋白表达量显著增加(P0.05)。与溃疡组相比,罗格列酮组的大鼠DAI、CDMI和HS评分均显著降低(P0.05);结肠组织中SOD含量显著增加,MDA和MPO的含量显著降低(P0.05);PPARγ的mRNA和蛋白表达量显著增加(P0.05);NFκB和TNF-α的mRNA和蛋白表达量显著降低(P0.05)。结论:罗格列酮可以通过增加SOD和PPARγ表达,降低MDA、MPO、NFκB和TNF-α表达来缓解炎症反应,对溃疡性结肠炎起到保护作用。     

马齿苋多糖对溃疡性结肠炎小鼠肠黏膜sIgA及病理表现的影响

目的探讨马齿苋多糖对溃疡性结肠炎小鼠肠黏膜sIgA及病理表现的影响。方法应用硫酸葡聚糖钠(DSS)制备溃疡性结肠炎小鼠模型,随机分成两组:正常对照组、模型组,造模成功后模型组再分为自然恢复组、马齿苋多糖治疗组。分别于造模后、给药7d后处死小鼠,进行肠道菌群、肠黏膜sIgA及结肠组织病理学检测。结果 DSS造模后模型组小鼠肠道菌群失调、肠黏膜sIgA含量下降、结肠组织有病理改变。马齿苋多糖治疗7d后治疗组小鼠肠道双歧杆菌和乳酸杆菌数量明显上升,肠黏膜sIgA含量上升、结肠组织病理改变减轻。结论马齿苋多糖可以提高双歧杆菌和乳酸杆菌数量,提高肠黏膜sIgA含量,改善结肠组织病理变化,对溃疡性结肠炎发挥了一定的治疗作用。     

Effects of recombinant human intestinal trefoil factor on trinitrobenzene sulphonic acid induced colitis in rats

Intestinal trefoil factor (ITF) has been proved to be effective in treatment of ulcerative colitis. However, the mechanisms of it remain unclear. In this study, we observed the effects of combined treatment with 5-aminosalicylic acid (5-ASA) and recombinant human ITF (rhITF) on the expression of Myeloperoxidase (MPO), nuclear factor-κB (NF-κB) and epidermal growth factor (EGF) in trinitrobenzene sulphonic acid (TNBS) induced colitis in rats. Forty Sprague-Dawley (SD) male rats which were induced to distal colitis by the colonic administration of TNBS, were randomly divided into four groups and colonically treated with normal saline (A), 5-ASA (B), rhITF (C), respectively. The macroscopic and histological changes of the colon, activities of MPO, expressions of serum EGF and tissue NF-κB were detected. The results showed that manifestation, colonic damage score and MPO activities of the rats treated with 5-ASA or/and rhITFs were improved, serum EGF production was augmented and expression of tissue NF-κB was down-regulated. Single usage of 5-ASA or rhITF had no significant difference, but combined using of them had more significant and noticeable effects compared to any single treatment. It could be concluded that topical treatment with 5-ASA and rhITF had beneficial effects in treating TNBS-induced colitis of rats and combined treatment was better than single treatment. It was possibly related to suppression of neutrophil infiltration, down-regulation expression of NF-κB and up-regulation expression of EGF.     

Effects of proanthocyanidins from grape seed on treatment of recurrent ulcerative colitis in rats

The aim of the present study was to investigate the therapeutic effect and mechanism of proanthocyanidins from grape seed (GSPE) in the treatment of recurrent ulcerative colitis (UC) in rats. To induce recurrent colitis, rats were instilled with 2,4,6-trinitrobenzenesulfonic acid (TNBS) (80?mg/kg) into the colon through the cannula in the first induced phase, and then the rats were instilled a second time with TNBS (30?mg/kg) into the colon on the sixteenth day after the first induction UC. Rats were intragastrically administered GSPE (200?mg/kg) per day for 7?days after twice-induced colitis by TNBS. Sulfasalazine at 500?mg/kg was used as a positive control drug. Rats were killed 7?days after GSPE treatment. The colonic injury and inflammation were assessed by macroscopic and macroscopic damage scores, colon weight/length ratio (mg/cm), and myeloperoxidase activity. Then, superoxide dismutase, glutathione peroxidase, inducible nitric oxide synthase (iNOS) activities, and the levels of malonyldialdehyde, glutathione, and nitric oxide in serum and colonic tissues were measured. Compared with the recurrent UC group, GSPE treatment facilitated recovery of pathologic changes in the colon after induction of recurrent colitis, as demonstrated by reduced colonic weight/length ratio and macroscopic and microscopic damage scores. The myeloperoxidase and iNOS activities with malonyldialdehyde and nitric oxide levels in serum and colon tissues of colitis rats were significantly decreased in the GSPE group compared with those in the recurrent UC group. In addition, GSPE treatment was associated with notably increased superoxide dismutase, glutathione peroxidase activities, and glutathione levels of colon tissues and serum of rats. GSPE exerted a protective effect on recurrent colitis in rats by modifying the inflammatory response, inhibiting inflammatory cell infiltration and antioxidation damage, promoting damaged tissue repair to improve colonic oxidative stress, and inhibiting colonic iNOS activity to reduce the production of nitric oxide.     

Luminal antioxidants enhance the effects of mesalamine in the treatment of chemically induced colitis in rats

Previous experiments in rats with chemically induced colitis have shown that the antioxidant N-acetylcysteine plus mesalamine (5-ASA) exerted a significantly greater therapeutic effect in promoting mucosal healing when compared to either agent alone. The aims of the present study were to compare the effects of three antioxidants plus mesalamine vs. 5-ASA alone in treatment of colitis induced by trinitrobenzene sulfonic acid (TNBS) in rats. Methods: Three days following induction of TNBS colitis, rats received 8 days of rectal therapy with 5-ASA, or 5-ASA plus vitamin C (ascorbic acid), 5-ASA plus phenyl butylnitrone (PBN) and 5-ASA plus vitamin E (alpha-tocopherol). Distal colonic tissues were examined for microscopic colitis and myeloperoxidase (MPO) activity. Results: Global assessments of microscopic colitis induced by TNBS indicated that 5-ASA alone significantly changed colonic injury by -31%. Combination therapy with ascorbic acid plus 5-ASA or alpha-tocopherol plus 5-ASA caused further significant change in TNBS colitis by -65 and -82%, respectively. Each of these values was significantly below scores observed with 5-ASA as monotherapy. Reduction in colitis with PBN plus 5-ASA was not different from 5-ASA alone. MPO activity was decreased significantly in response to monotherapy with 5-ASA and each of the antioxidants plus 5-ASA when compared to TNBS. alpha-Tocopherol plus 5-ASA, however, was the only treatment strategy that reduced significantly MPO activity below that recorded for 5-ASA alone. In conclusion, our results indicate that antioxidants other than N-acetylcysteine significantly enhance the therapeutic effectiveness of 5-ASA in the treatment of TNBS colitis. alpha-Tocopherol plus 5-ASA exerted profound anti-inflammatory and reparative effects upon colitis induced by TNBS.     

Antibiotic treatment with ampicillin accelerates the healing of colonic damage impaired by aspirin and coxib in the experimental colitis. Importance of intestinal bacteria, colonic microcirculation and proinflammatory cytokines

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used for their anti-inflammatory, analgesic and antipyretic effects, however their use is associated with the broad spectrum of side effects observed in human as well as the experimental animals. Despite damaging activity of NSAIDs in upper gastrointestinal (GI) tract, these drugs exert deleterious influence in lower GI tract, including colon. The role of GI microflora in the pathogenesis of NSAIDs-induced experimental colonic damage is not completely understood. The aim of this study was 1) to evaluate the relative importance of the GI microflora on the experimental colonic damage in the presence of caused by NSAID, and 2) to assess the efficacy of antibiotic treatment with ampicillin on the process of healing of colitis. We compared the effect of vehicle, ASA applied 40 mg/kg intragastrically (i.g.) or the selective cyclooxygenase (COX)-2 inhibitor, celecoxib (25 mg/kg i.g.) without or with ampicillin treatment (800 mg/kg i.g.) administered throughout the period of 10 days, on the intensity of TNBS-induced colitis in rats. The severity of colonic damage, the alterations in the colonic blood flow (CBF) and myeloperoxidase (MPO) activity, the mucosal expression of TNF-α, IL-1β, COX-2, VEGF and iNOS and the plasma concentration of TNF-α and IL-1β were assessed. In all rats, the faeces samples as well as those from the colonic mucosa, blood, liver and spleen underwent microbiological evaluation for intestinal bacterial species including Escherichia coli and Enterococcus spp. The administration of TNBS resulted in macroscopic and microscopic lesions accompanied by the significant fall in the CBF, an increase in tissue weight and 4-5-fold rise in the MPO activity and a significant increase in the plasma IL-1β and TNF-α levels. ASA or celecoxib significantly increased the area of colonic lesions, enhanced MPO activity and caused the marked increase in colonic tissue weight and plasma IL-1β and TNF-α levels, as well as an overexpression of mRNA for IL-1β and TNF-α, COX-2, VEGF and iNOS in the colonic tissue. ASA and coxib also resulted also in a significant increase of E. coli counts in the stool at day 3 and day 10 day of the observation compared with the intact rats. Moreover, E. coli translocation from the colon to the blood and extraintestinal organs such as liver and spleen in the group of rats treated without or with ASA and coxib. E. coli was the most common bacteria isolated from these organs. Treatment with ampicillin significantly attenuated the ASA- or celecoxib-induced increase in plasma levels of IL-1β and TNF-α and suppressed the mucosal mRNA expression for IL-1β and TNF-β, COX-2, iNOS and VEGF in the colonic mucosa. Ampicillin administration caused a significant fall in the number of E. coli in the faeces at day 3 and day 10 of observation in ASA- and coxib-treated rats with colitis. Antibiotic therapy markedly reduced bacterial translocation to the colonic tissue and the extraintestinal organs such as the liver and spleen. We conclude that administration of ASA and to lesser extent of celecoxib, delays the healing of experimental colitis and enhances the alterations in colonic blood flow, proinflammatory markers such as IL-1β, TNF-α, COX-2, iNOS and VEGF and increased intestinal mucosal permeability resulting in the intestinal bacterial translocation to the blood, spleen and liver. Antibiotic treatment with ampicillin is effective in the diminishing of the severity of colonic damage, counteracts both the NSAID-induced fall in colonic microcirculation and bacterial E.coli translocation to the extraintestinal organs.     

Efficacy of Setarud (IMod), a novel drug with potent anti-toxic stress potential in rat inflammatory bowel disease and comparison with dexamethasone and infliximab

The inflammatory bowel disease (IBD) is an idiopathic, immune-mediated and chronic intestinal condition. In the present study, the effect of Setarud (IMOD), a novel natural drug with known immunomodulatory, anti-inflammatory and antioxidant properties was investigated in experimental colitis in rats and compared with the dexamethasone and infliximab. Immunologic colitis was induced by intracolonic administration of a mixture of trinitrobenzene sulfonic acid (TNBS) and absolute ethanol in male Wistar rats. Animals were divided into 6 groups of sham (normal group), control (vehicle-treated), positive control (dexamethasone 1 mg/kg/day given orally and infliximab 5 mg/kg/day given subcutaneously) and 3 Setarud-treated groups (13.3, 20, 30 mg/kg/day given intraperitoneally). The treatment continued for 14 consecutive days and then animals were decapitated on the day 15 and distal colons were removed for macroscopic, microscopic, and biochemical assays. Biochemical markers, including TNF-alpha, IL-1beta, ferric reducing/antioxidant power (FRAP), myeloperoxidase (MPO) activity and thiobarbitoric acid-reactive substance (TBARS) were measured in the homogenate of colonic tissue. A remarkable reduction in macroscopic and histological damage scores was observed in the animals treated with Setarud. These findings were confirmed by decreased levels of TNF-alpha, interleukin-1beta, MPO activity and TBARS, and raised levels of FRAP in the colon tissue. These observations confirmed the immunomodulatory, anti-inflammatory and antioxidant properties of Setarud in experimental colitis, which was comparable to those of dexamethasone and infliximab.     

The anti-inflammatory effect of leptin on experimental colitis: involvement of endogenous glucocorticoids

The present study was designed to compare the effect of leptin on acute colonic inflammation with that of acute stress exposure, which acts via the hypothalamic-pituitary-adrenal (HPA) axis. Sprague-Dawley rats of both sexes were administered intrarectally with acetic acid. Either leptin (10 microg/kg; i.p.) or saline was injected immediately before and 6 h after the induction of colitis. A group of rats was exposed to water avoidance stress (WAS) for 30 min at the 6th h of colitis induction. RU-486 (2 mg/kg; i.p.), a glucocorticoid receptor antagonist, was injected intraperitoneally, at 12 and 1 h before the initial leptin injection, and at 1 h before the second leptin injection or exposure to WAS. Rats were decapitated at 24 h and the distal 8 cm of the colon were removed for macroscopic and microscopic scoring, determination of tissue wet weight index (WI) and tissue myeloperoxidase activity (MPO). Acetic acid-induced colitis significantly increased macroscopic and microscopic damage scores, WI and MPO, compared to control group. Exposure to acute WAS or treatment with leptin reduced the elevations in damage scores, WI and MPO induced by colitis, but no additive inhibitory effect was observed when WAS and leptin were applied together. RU-486 treatment reversed the inhibitory effects of leptin or WAS on colonic inflammation. Our results demonstrate that exogenous leptin mimics the effects of HPA axis activation on colitis-induced inflammatory process. The results also suggest that the anti-inflammatory effect of leptin involves a tissue neutrophil-dependent mechanism and is dependent on the release of glucocorticoids.     

A protective effect of the synthetic coumarine derivative Cloricromene against DNB-colitis in the rat

Biologic therapies, namely antibodies against tumor necrosis factor-alpha (TNF- alpha) or its receptors, have been recently introduced for the treatment of patients with inflammatory bowel disease (IBD). In the present study the effects of cloricromene, an agent with known antithrombotic actions and with demonstrated anti-TNF- alpha activity were investigated in a rat model of experimental colitis induced with dinitrobenzenesulphonic acid (DNB)/ethanol. We investigated three experimental groups: (i) sham-colitis with vehicle-treatment (controls, n = 6), (ii) colitis with vehicle-treatment (saline, 0.1 ml s.c., daily) (DNB-V, n = 7), (iii) colitis with cloricromene-treatment (10 mg/kg/day s.c.; DNB-C, n = 8). After 7 days, the weight gain, colon wet weight, macroscopic damage score, coagulation parameters, colon mucosal myeloperoxidase activity (MPO), and tissue concentrations of TNF- alpha and of macrophage inhibitory peptide-2 (MIP-2) were assessed. The macroscopic damage scores, colon wet weights, and tissue MIP-2 levels were significantly increased in untreated and in cloricromene-treated rats compared with controls. Cloricromene treatment was associated with a minor body weight loss (p < 0.025) and significantly reduced tissue concentrations of MPO and TNF-alpha (p < 0.02, both). Blood coagulation parameters were not affected by treatment. In the DNB-model treatment with cloricromene effectively reduces tissue levels of TNF- alpha and of myeloperoxidase, whereas MIP-2 concentrations were not influenced. Blood coagulation parameters remained unchanged indicating safety of treatment. Since biological therapies frequently fail to improve disease course of IBD, other therapies with similar targets should be further investigated.     

Oxytocin ameliorates oxidative colonic inflammation by a neutrophil-dependent mechanism

Oxytocin (OT), a nonapeptide produced in the paraventricular and the supraoptical nuclei in the hypothalamus has a wide range of effects in the body. However, the role of OT on the gastrointestinal (GI) tract has to be settled. OT may participate in the regulation of motility, secretion, blood flow, cell turnover and release of neurotransmitters and/or peptides in the GI tract, possesses antisecretory and antiulcer effects, facilitates wound healing and is involved in the modulation of immune and inflammatory processes. The present work was conducted to assess the possible therapeutic effects of OT against the acetic acid-induced colonic injury in the rat. METHODS: Colitis was induced by intracolonic administration of acetic acid (5%) in Sprague-Dawley rats (200-250 g). Either saline or OT (0.5 mg/kg) was injected subcutaneously, immediately after the induction of colitis and repeated two times a day for 4 days. On the 4th day, rats were decapitated and distal 8 cm of the colon were removed for the macroscopic and microscopic damage scoring, determination of tissue wet weight index (WI), malondialdehyde (MDA) levels, an end product of lipid peroxidation; glutathione (GSH) levels, a key antioxidant; and myeloperoxidase (MPO) activity, as an indirect index of neutrophil infiltration. Colonic collagen content, as a fibrosis marker was also determined. Lactate dehydrogenase (LDH) and tumor necrosis factor-alpha (TNF-alpha) levels were assayed in serum samples. In the acetic acid-induced colitis, macroscopic and microscopic damage scores, WI, MDA and MPO levels were significantly increased, while GSH levels were decreased when compared to control group (p <0.05-<0.001). Treatment with OT abolished the colitis-induced elevations in damage scores, WI, MDA and MPO levels and restored the GSH levels (p <0.05-0.001). Similarly, acetic acid increased the collagen content of colonic tissues and OT-treatment reduced this value to the level of the control group. Serum LDH and TNF-alpha levels were also elevated in the acetic acid-induced colitis group as compared to control group, while this increase was significantly decreased by OT treatment. The results suggest that OT, which improves the antioxidative state of the colonic tissue and ameliorates oxidative colonic injury via a neutrophil-dependent mechanism, requires further investigation as a potential therapeutic agent in colonic inflammation.     

Central effects of selective NK1 and NK3 tachykinin receptor agonists on two models of experimentally-induced colitis in rats

Peripheral tachykinins (TKs) are believed to play a role in the pathogenesis of inflammatory bowel diseases (IBD). In this study we investigated changes induced by central administration of two natural TK receptor agonists, NK(1) (PG-SPI) and NK(3) (PG-KII), on trinitrobenzene sulphonic acid (TNBS)- and dextran sodium sulphate (DSS)-induced experimental colitis in rats. Colitis was induced by instilling a single intracolonic dose of TNBS 50 mgkg(-1) (0.5 ml in 50% ethanol) or by oral administration of 5% DSS for 7 days. Each group of rats was intracerebroventricularly injected daily with PG-SPI and PG-KII (0.5, 5, and 50 microgkg(-1)). On day 3, TNBS-treated animals were killed and the severity of gut inflammation was evaluated by measuring myeloperoxidase (MPO) activity, interleukin-1beta (IL-1beta) production and by scoring macroscopic and histologic colonic damage. DSS-treated animals were checked daily for the length of survival and for stool consistency and faecal blood. In the TNBS group, PG-SPI and PG-KII increased scores for the severity of colonic damage, stimulated the production of IL-1beta and increased granulocyte infiltration into the colon (MPO activity). In the DSS group, PG-SPI and PG-KII decreased the percentage of surviving animals, and increased the number of rats that developed loose stools and blood in the faeces and the MPO activity. These results indicate that centrally injected NK(1) and NK(3) tachykinin receptor agonists play a proinflammatory role in experimentally-induced colitis in rats.     

Abolishment of TNBS-induced visceral hypersensitivity in mast cell deficient rats

Mucosal mast cells are implicated in visceral hypersensitivity associated with irritable bowel syndrome (IBS). In this study, we investigated the role of mast cells in the development of visceral hypersensitivity by using mast cell deficient (Ws/Ws) rats and their control (W+/W+). In W+/W+ rats, an injection of 2,4,6-trinitrobenzene sulfonic acid (TNBS) into the proximal colon produced a significant decrease in pain threshold of the distal colon. Severe mucosal necrosis and inflammatory cell infiltration with concomitant increase in tissue myeloperoxidase activity were observed in the proximal colon that was directly insulted by TNBS, whereas neither necrosis nor increased myeloperoxidase activity occurred in the distal colon, indicating that TNBS-induced hypersensitivity is not caused by the local tissue damage or inflammation in the region of the gut where distention stimuli were applied. On the other hand, TNBS failed to elicit visceral hypersensitivity in Ws/Ws rats. This finding indicates that mast cells are essential for development of TNBS-induced visceral hypersensitivity in rats. Since the severity of TNBS-induced proximal colon injury and MPO activity was not affected by mast cell deficiency, it is unlikely that abolishment of visceral hypersensitivity in mast cell deficient rats was a result of altered development of the primary injury in the proximal colon. There was no difference between sham-operated Ws/Ws and W+/W+ rats in colonic pain threshold to distention stimuli, indicating that mast cells play no modulatory roles in normal colonic nociception. The present results support the view that mucosal mast cells play key roles in the pathogenesis of IBS.