Release of endogenous opioids during a chronic IBD model suppresses the excitability of colonic DRG neurons

Background Endogenous opioids are implicated in pain‐regulation in chronic inflammatory bowel disease (IBD). We sought to examine whether endogenous opioids suppress the excitability of colonic nociceptive dorsal root ganglia (DRG) neurons during chronic IBD, and if so, whether modulation of underlying voltage‐gated K⁺ currents was involved. Methods The effects of chronic dextran sulfate sodium (DSS) colitis on afferent signaling in mice was studied using patch clamp recordings. Colonic DRG neurons were identified using Fast Blue retrograde labeling and recordings obtained from small DRG neurons (<40 pF). Key Results In current‐clamp recordings, the rheobase of neurons was increased 47% (P < 0.01) and action potential discharge at twice rheobase decreased 23% (P < 0.05) following incubation in colonic supernatants from chronic DSS mice. β‐endorphin increased 14‐fold, and tissue opioid immunoreactivity and expression in CD4+ cells observed by flow cytometry increased in chronic DSS colons. Incubation of naïve neurons in the μ‐opioid receptor agonist D‐Ala², N‐ MePhe⁴, Gly‐ol (DAMGO) (10 nM) partially recapitulated the effects of supernatants from DSS mice on rheobase. Supernatant effects were blocked by the μ‐opioid receptor antagonist naloxone. In voltage clamp, chronic DSS supernatants and DAMGO increased I_A K⁺ currents. Conclusions & Inferences The release of endogenous opioids during chronic inflammation in mice suppresses the excitability of nociceptive DRG neurons. Targeting immune cells may provide a novel means of modulating IBD pain.     

参白解毒方显著抑制小鼠结直肠腺瘤的形成及癌变： 基于PTEN/PI3K/AKT通路

目的 探讨参白解毒方（SBJDF）对结直肠腺瘤形成及癌变的影响及其对PTEN/PI3K/AKT信号通路的调控作用。方法 将4周龄的雄性C57BL/6小鼠随机分为对照组（10只）、AOM/DSS模型组（20只）、参白解毒方低剂量组（14 g/kg,10只）和参白解毒方高剂量组（42 g/kg,10只）。除对照组外,其余各组采用AOM/DSS诱导小鼠结直肠腺瘤癌变模型,处理组于造模中给予参白解毒方灌胃干预。比较各组小鼠的生存率、体质量和生存状态,观察肠道组织腺瘤形成及癌变等病理情况,免疫组化检测肠道组织PTEN/PI3K/AKT信号通路相关分子的表达。结果 参白解毒方干预后小鼠的肿瘤发生率、数量和体积均显著低于AOM/DSS模型组,且高剂量的参白解毒方抑制效果更佳。HE病理切片结果显示模型组已形成腺癌,而参白解毒方可以抑制腺瘤的形成及癌变,参白解毒方低剂量组小鼠肠道同时存在腺瘤低级别瘤变和高级别瘤变,参白解毒方高剂量组小鼠肠道以正常粘膜组织为主,仅发现局部少量腺瘤低级别瘤变。机制研究发现模型组血浆中miRNA-222表达高于空白组（P<0.05）,用药各组miRNA-222的表达量较模型组下调（P<0.01）;小鼠肠道组织免疫组化结果显示,与AOM/DSS模型组相比,参白解毒方处理后PTEN、p-PTEN、GSK-3β表达上调,且在低剂量组、高剂量组表达有依次递增趋势;p-GSK-3β、PI3K、AKT、p-AKT、β-catenin、c-myc、CyclinD1、Survivin表达下调,且在低剂量组、高剂量组表达呈递减趋势。结论 参白解毒方可以显著抑制小鼠结直肠腺瘤形成及癌变,其作用机制可能与调控miRNA-222及影响PTEN/PI3K/AKT信号通路有关。     

Disease modifying effect of statins in dextran sulfate sodium model of mouse colitis

Objective: We evaluated the disease modifying effect of simvastatin and atorvastatin in Dextran Sulfate Sodium (DSS) model of colitis. Materials and methods: Thirty, 8-week old female Swiss-Webster mice were separated into 5 groups (n = 6/group). Colitis was induced by feeding 4 % DSS solution for 7 days. Following discontinuation of DSS, over the next 7 days, the groups orally received simvastatin (20 mg/kg/day), atorvastatin (60 mg/kg/day), vehicle only (0.75 % methylcellulose), subcutaneous 30 μg injections of anti-TNFα monoclonal antibody or intraperitoneal anti-mouse apolipoprotein A-I antibody respectively. Disease activity Index (DAI) was determined daily by a blinded investigator. Results: The mean reduction in DAI scores from day 7 to day 14 for anti-TNFα group, simvastatin and atorvastatin group were 74 %, 76 % and 64 %, respectively as compared to 41 % reduction in vehicle and anti-apolipoprotein A-I antibodytreated groups. Conclusions: This finding suggests that statins may have the ability to modify the disease activity in the DSS model of colitis and the disease modifying effect is comparable to anti-mouse TNFα treatment in this model. Received 23 October 2006; returned for revision 27 February 2007; accepted by I. Ahnfelt-R?nne 16 August 2007     

Prevention of colitis-associated carcinogenesis in a mouse model by diet supplementation with ursodeoxycholic acid

Bile acids in the intestinal lumen contribute to the homeostatic regulation of proliferation and death of the colonic epithelial cells: Deoxycholic acid (DCA) appears to enhance and ursodeoxycholic acid (UDCA) to attenuate the process of chemically induced carcinogenesis. We studied the effects of UDCA on colitis-related colorectal carcinogenesis. Three groups of 25 mice were given 0.7% dextran sulphate in drinking water for 7 days and pure water for 10 days and were fed a standard diet containing double iron concentration. In 2 groups, the diet was supplemented with 0.2% cholic acid (CA), the precursor of DCA, or with 0.4% UDCA. After 15 cycles, the histology, the expression of MUC2, beta-catenin, p27 and p16 and the fecal water concentration of DCA and UDCA were investigated. All animals showed colitis with similar severity and histologic as well as immunophenotypic alterations, resembling those of human colitis. Among the animals fed the nonsupplemented diet, 46% developed colorectal adenocarcinomas and 54% anal-rectal squamous cell carcinomas. The prevalence of dysplasia and carcinomas did not change significantly in the animals given CA. Among the mice fed with UDCA, none developed adenocarcinomas and 20% squamous carcinomas. Dysplastic lesions were found in 88%, 67% and 40% of each group, respectively. The prevalence of dysplasia as well as of carcinoma showed an inverse relationship to the UDCA concentration in the fecal water. These data indicate that UDCA suppresses colitis-associated carcinogenesis. This model is suitable for investigation of the mechanism of the anticarcinogenic effect of UDCA in vivo.     

脾虚湿盛肝郁证溃疡性结肠炎大鼠模型的建立与评价

目的:建立并评价符合中医证候特点的脾虚温盛肝郁证溃疡性结肠炎(ulcerative colitis,UC)大鼠模型.方法:45只SPF级SD大鼠随机分为正常对照组、葡聚糖硫酸钠(DSS)组、病证结合组、模型组.正常对照组正常饲养,DSS组定量灌胃10％DSS溶液,病证结合组采用环境、饮食、情绪干预造模,模型组采用DSS...     

气相色谱法测定当归芍药散挥发油中藁本内酯的含量

目的:建立气相色谱法测定当归芍药散挥发油中藁本内酯含量的方法.方法:采用DB-WAX毛细管柱(0.32 mm×15 m,0.25 μm),FID检测器,正十八烷为内标物.结果:藁本内酯在0.14～0.70 g·L-1线性关系良好(r =0.999 9),平均加样回收率为98.64％,RSD 2.62％ (n =6).结论:所建立的方法快速,简便,准确,重复性好,专属性好,可用于当归芍药散的质量评价.     

N-乙酰半胱氨酸对硫酸葡聚糖钠诱导的实验性肠炎的预防及治疗作用

目的：探讨还原型巨噬细胞诱导剂N-乙酰半胱氨酸（N—Acetylcysteine，NAC）对硫酸葡聚糖钠（Dextran Sodium Sulphate，DSS）诱导的小鼠实验性肠炎的预防及治疗作用。方法：建立DSS实验性小鼠肠炎模型，NAC及氧化型巨噬细胞诱导剂N，N’-联乙醇-L-胱氨酸（N，N’-diacetyle—L-cystine，（NACOMe）2）在致模前后腹腔注射；检测腹腔巨噬细胞中还原型谷胱甘肽（GSH）与氧化型谷胱甘肽（GSSG）的变化；对结肠进行病理学评价，并检测结肠IL-4、IFN—g的表达。结果：NAC预处理组：结肠长度和病理学指标均优于其他预处理组，腹腔巨噬细胞内GSH及GSH／GSSG升高；结肠分泌的IL～4、IFN-γ明显降低。NAC治疗组：体重增加程度明显高于其它治疗组，结肠炎症及黏膜损伤较轻，腹腔巨噬细胞内GSSG明履减低，GSH和GSH／GSSG升高，病变结肠分泌的IL-4、IFN-γ明显降低。结论：还原型巨噬细胞诱导剂NAC可以通过诱导巨噬细胞内GSH产生增多从而减轻实验性肠炎的黏膜损伤及临床症状，对DSS诱导的实验性肠炎有一定的预防及治疗作用。