Inhibitors of poly (ADP-ribose) polymerase modulate signal transduction pathways in colitis

During inflammatory bowel diseases, oxidative and nitrosative stress induces DNA damage and activation of the nuclear enzyme poly (ADP-ribose) polymerase (PARP), resulting in depletion of intracellular energetics, intestinal barrier dysfunction and cellular death. The aim of our study was to evaluate the therapeutic efficacy of in vivo inhibition of PARP in experimental colitis, which was induced by rectal instillation of trinitrobenzene sulfonic acid (TNBS) in rats. In vehicle-treated rats, TNBS treatment resulted in colonic erosion and ulceration. Neutrophil infiltration (indicated by myeloperoxidase activity in the colon) was associated with formation of nitrotyrosine and marked apoptosis. Elevated levels of plasma nitrate/nitrite, metabolites of nitric oxide (NO), were also found. These inflammatory events were associated with the activation of nuclear factor-kappa B (NF-kappa B) and activator protein-1 (AP-1) in the colon; NF-kappa B was maximally activated at 3 and 7 days, whereas AP-1 increased 1 day after TNBS administration and declined thereafter. Treatment of the rats with the PARP inhibitors, 3-aminobenzamide or 1,5-dihydroxyisoquinoline, resolved colonic damage and reduced plasma levels of NO metabolites. Resolution of the damage was associated with reduction of neutrophil infiltration, nitrotyrosine formation and apoptosis. Treatment with PARP inhibitors also reduced DNA binding of NF-kappa B and AP-1 in the colon. These data demonstrate that pharmacological inhibition of PARP ameliorates colitis. Reduction of the inflammatory process is associated with modification of the activation of signal transduction pathways.     

具备高同型半胱氨酸血症的实验性结肠炎模型的建立

目的建立具备高同型半胱氨酸血症(HHcy)的实验性结肠炎模型,初步探讨Hcy对结肠炎症损伤的影响。方法将SD大鼠分为4组:正常对照组(NS灌肠+皮下注射NS)、正常对照+Hcy注射组(NS灌肠+皮下注射Hcy)、TN-BS模型对照组(TNBS/乙醇灌肠+皮下注射NS)、TNBS模型+Hcy注射组(TNBS/乙醇灌肠+皮下注射Hcy)。以TN-BS/乙醇混合溶液(100 mg·kg-1TNBS加入等体积NS)灌肠1次制备结肠炎模型后,采用皮下注射同型半胱氨酸(0.03μmol·kg-1,每天2次,间隔8 h,连续30 d)造成HHcy模型。实验结束后通过高效液相荧光法(HPLC-FD)检测血浆和结肠粘膜Hcy水平,进行DAI评分并取结肠组织进行HE染色评分,结肠组织匀浆检测MPO活性。结果与正常对照组比较,TNBS模型对照组大鼠DAI和HI评分增高(P<0.01),结肠组织MPO活性增高(P<0.01)。与TNBS模型对照组比较,TNBS模型+Hcy注射组大鼠血浆和结肠粘膜Hcy水平明显增高(P<0.01),DAI和HI评分明显增高(P<0.01),结肠组织MPO活性明显增高(P<0.01)。结论皮下注射同型半胱氨酸可以建立具备高同型半胱氨酸血症的实验性结肠炎模型,可用于探讨Hcy在结肠炎中的作用机制。     

Influence of simultaneous inhibition of cyclooxygenase-2 and inducible nitric oxide synthase in experimental colitis in rats

The inflamed mucosa in ulcerative colitis produces high amount of prostaglandin (PG) and nitric oxide (NO) through inducible enzymes: cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS), respectively, implicating them as potential anti-inflammatory drug targets. COX-2 or iNOS-related treatments in different models of colitis have yielded ambiguous results ranging from exacerbation of disease to abolition of inflammation. iNOS and COX-2 induction is blocked by potent anti-inflammatory glucocorticoids, however, serious side effects including relapses limit their usefulness in colitis for long time. Simultaneous inhibition of iNOS and COX-2 was investigated in the current study in 2, 4, 6 trinitrobenzene sulphonic acid (TNBS)-induced colitis in rats. Treatment group received rofecoxib, aminoguanidine hydrochloride or their combination at different doses at 48, 36, 24, 12 and 1 h prior to induction of colitis and 12 h later. Colonic myeloperoxidase (MPO), COX-2, nitrate and nitrite, tumor necrosis factor-α (TNF-α) and lipid peroxidation were maximally reduced by combination of 10 mg/kg rofecoxib and 30 mg/kg of aminoguanidine hydrochloride in TNBS-induced colitis in rats. However, maximum increase in SOD and catalase was noted by this combination. Rats treated with rofecoxib, aminoguanidine hydrochloride and their combinations reduced the inflammation, acute colonic damage produced by TNBS as verified by macroscopic changes in colon. Combination of rofecoxib (10 mg/kg) and aminoguanidine hydrochloride (30 mg/kg) has maximal protective effect on colonic injury induced by TNBS enema which is probably, via mechanism of local inhibition of iNOS and COX-2 activity in colonic mucosa and support the idea that simultaneous inhibition of iNOS and COX-2 inhibitors have a promising potential in the treatment of colitis.     

Effect of intracolonic benzalkonium chloride on trinitrobenzene sulphonic acid-induced colitis in the rat

Background:

We investigated the effects of benzalkonium chloride (BAC) on trinitrobenzene sulphonic acid (TNBS)-induced colitis in rats.

Methods:

TNBS was administered intrarectally before and/or after BAC treatment. In the first study, the effects of treatment with BAC 6, 12 or 24 h after TNBS were examined. In the second study, animals were treated with BAC before, after or before and after TNBS, and were examined 7 days later. The severity of colitis was assessed by macroscopic and histological scoring of the colonic damage and by determination of colonic myeloperoxidase (MPO) activity. Macrophages and CD4⁺ and CD8⁺ T cells were examined by immuno-histochemistry.

Results:

When BAC was instilled into the colon 6, 12 or 24 h after TNBS, weight loss and macroscopic and histological features of the colon were similar to that of controls (TNBS alone). In contrast, MPO activity was significantly reduced in all three groups post-treated with BAC. In the groups examined 7 days after TNBS treatment, rats post-treated with BAC exhibited increased weight gain and significantly reduced macroscopic damage and MPO activity compared to the TNBS control group. Rats pre-treated with BAC exhibited less macroscopic damage of the colon than rats receiving only TNBS, but histological damage, MPO and weight gain were unchanged from TNBS controls. Immunohistochemistry revealed that BAC pre-treatment increased the numbers of macrophages and T cells in the colon. After TNBS treatment, macrophage accumulation was evident in the colon, but T cells were scarce. However, these cells were preserved or enhanced in the colonic mucosa in TNBS-treated rats that had been pre-treated with BAC.

Conclusions:

Treatment with BAC, particularly after induction of colitis, produces a significant reduction in the severity of tissue injury and inflammation through mechanisms that are not fully understood.

     

龙胆苦苷对结肠炎小鼠的治疗作用

目的探究龙胆苦苷对结肠炎小鼠的治疗作用。方法采用2,4,6-三硝基苯磺酸(TNBS)-乙醇溶液诱导结肠炎小鼠模型,测定龙胆苦苷给药后对小鼠体质量、结肠指数、胸腺质量、结肠组织中髓过氧化物酶(MPO)活性以及血清炎症细胞因子TNF-α和IL-8的影响,并通过免疫组化法观察龙胆苦苷对小鼠结肠组织中环氧合酶-2(COX-2)蛋白表达的影响。结果给药1周后,龙胆苦苷各剂量组小鼠体质量与模型组相比显著改善;小鼠结肠指数、结肠组织中MPO活性以及炎性细胞因子TNF-α和IL-8与模型组相比均显著降低(P<0.05);免疫组化结果显示,龙胆苦苷能降低结肠炎小鼠组织中环氧合酶-2(COX-2)的蛋白表达。结论龙胆苦苷能修复TNBS-乙醇溶液诱导的小鼠结肠损伤,对小鼠结肠炎有显著的治疗作用。     

Mechanism underlying the reversal of contractility dysfunction in experimental colitis by cyclooxygenase-2 inhibition

Inflammatory bowel diseases are associated with reduced colonic contractility and induction of cyclooxygenase-2. In this study a possible role of cyclooxygenase-2 in and the underlying mechanism of the reduced contractility were investigated in experimental colitis. The effects of meloxicam, a cyclooxygenase-2 selective inhibitor were examined on colonic contractility and MAP kinase p38 and ERK_1/2 expression. Colitis was induced in Sprague-Dawley male rats by intra-colonic instillation of trinitrobenzenesulphonic acid (TNBS; 40 mg/rat in 50 ethanol). The animals were divided into three groups. Group 1 (n=9) received meloxicam (3 mg/kg-day) gavage 1 h before and 1 day (Group 2) after induction of colitis. Group 3 (n=9) received phosphate buffered saline (PBS) in a similar manner and served as colitic control. The non colitic control animals received meloxicam in a similar manner. The animals were sacrificed after 5 days of treatment, colon was cleaned with PBS and colonic smooth muscle was obtained which was used in this study. Meloxicam treatment given 1 h before or 1 day after administration of colitis restored the reduced colonic contractility without affecting the sensitivity to carbachol. The levels of colonic smooth muscle IL-1β mRNA, PGE₂, ERK_1/2, p38, malondialdehyde, myeloperoxidase activity and colonic mass were increased, whereas the body weight was decreased due to TNBS. The changes except colonic muscle mass and p38 expression were reversed by meloxicam treatment. These findings indicate that restoration of reduced colonic contractility by meloxicam is mediated by ERK_1/2, and that ERK_1/2 may serve as an important anti inflammatory target for treatment of colitis.     

Protective effect of taurohyodeoxycholic acid from Pulvis Fellis Suis on trinitrobenzene sulfonic acid induced ulcerative colitis in mice

Ulcerative colitis is a nonspecific inflammatory disorder characterized by oxidative and nitrosative stress, leucocyte infiltration and up-regulation of pro-inflammatory cytokines. The aim of this study is to evaluate the effect of taurohyodeoxycholic acid (THDCA) isolated from Pulvis Fellis Suis on acute ulcerative colitis model induced by trinitrobenzene sulfonic acid (TNBS) in mice. The efficacy of THDCA was studied by macroscopical and histological scoring systems as well as myeloperoxidase (MPO) activity. Serum levels, including tumor necrosis factor (TNF)-α and interleukin (IL)-6 were assayed by enzyme-linked immunoassay. The expression of cyclooxygenase (COX)-2 in the colons was assessed by immunohistochemical analysis. Treatment with THDCA in doses of 25, 50 and 100 mg/kg/day and sulfasalazine in a dose of 500 mg/kg/day used as reference for 7 consecutive days after the induction of colitis, significantly decreased colonic MPO activity, TNF-α, IL-6 serum levels and the expression of COX-2 in colon compared with TNBS induced ulcerative colitis model group. Moreover, THDCA attenuated the macroscopic colonic damage and the histopathological changes induced by TNBS. All the effects of these parameters were comparable to that of the standard sulfasalazine, especially at the highest dose level. The results suggested that THDCA from Pulvis Fellis Suis has a protective effect in TNBS-induced ulcerative colitis which might be due to its anti-inflammatory activities, and that it may have therapeutic value in the setting of inflammatory bowel disease.     

Modulation by heme and zinc protoporphyrin of colonic heme oxygenase-1 and experimental inflammatory bowel disease in the rat

Reactive oxygen species, suggested to be involved in inflammatory bowel disease, may be modulated by endogenous anti-oxidant products of heme oxygenase-1 (HO-1). In the present work, HO-1 expression in trinitrobenzene sulphonic acid (TNBS)-induced colitis in the rat and the effects of HO-1 modulation, particularly by the HO-1 inducer, heme, were further evaluated. Colitis was induced by intracolonic challenge with TNBS and assessed macroscopically and by myeloperoxidase (MPO) assay. Heme oxygenase activity was determined by measurement of bilirubin formation and HO-1 protein expression was determined by Western blotting. TNBS challenge led to an early and substantial induction of HO-1 protein expression and heme oxygenase activity in the colon that peaked after 48-72 h and declined over 10 days. Heme (30 micromol/kg/day, s.c) increased colonic HO-1 protein expression and enzyme activity and decreased colonic damage and myeloperoxidase activity. Short-term administration of cadmium chloride (2 mg/kg, s.c.), another known HO-1 inducer, also reduced the colonic injury and myeloperoxidase levels. In contrast, the HO-1 inhibitor, zinc protoporphyrin (50 micromol/kg/day, s.c) significantly increased the colonic damage and myeloperoxidase activity over 10 days, as did tin protoporphyrin (30 micromol/kg/day, s.c). These results support the proposal that induction of HO-1 provides a protective mechanism in this model under both acute and more-chronic conditions, and that its selective up-regulation could thus be of therapeutic potential in colitis.     

1,8-cineole (eucalyptol), a monoterpene oxide attenuates the colonic damage in rats on acute TNBS-colitis.

The monoterpene oxide, 1,8-cineole (cineole, eucalyptol) was examined for its possible influence on the acute phase of trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats. The test compound, 1,8-cineole (200 and 400 mg/kg) or vehicle (1 ml, 2% Tween 80) was instilled rectally, 24, and 2 h before (pre-treatment) or 2 and 24 h after (post-treatment) the induction of colitis by intracolonic administration of TNBS (0.25 ml of 25 mg of TNBS in 50% ethanol). Rats were killed 48 h after colitis induction and colonic segments were analysed for gross damage scores, changes in wet weights, myeloperoxidase activity, an indicator of neutrophilic infiltration and glutathione level, a major cellular antioxidant. TNBS induced an extensive inflammation and ulceration in the colon. Colonic damage was associated with an increase in myeloperoxidase activity and by a decrease in glutathione. When compared to vehicle-treated TNBS controls, a marked reduction in gross damage scores and wet weights (mg/cm) of colonic segments were evident in animals pre-treated but not post-treated with 1,8-cineole. Cineole also significantly reduced the myeloperoxidase activity, and caused repletion of glutathione. These results confirm the anti-inflammatory action of 1,8-cineole and suggest its potential value as a dietary flavoring agent in the prevention of gastrointestinal inflammation and ulceration.     

Acute effects of the cys-leukotriene-1 receptor antagonist, montelukast, on experimental colitis in rats.

Cysteinyl leukotrienes play a part in inflammatory reactions such as inflammatory bowel diseases. The aim of the present study was to evaluate the acute effects of a cys-leukotriene-1 receptor antagonist, montelukast, on trinitrobenzene sulphonic acid (TNBS)-induced colitis in rats. Montelukast (5, 10 or 20 mg kg(-1) day(-1)), a 5-lipoxygenase inhibitor, zileuton (50 or 100 mg kg(-1) day(-1), a positive control), or the vehicle was administered intracolonically to the rats twice daily throughout the study, starting 12 h before the induction of colitis with TNBS. The severity of colitis (macroscopic and histological assessment, as well as myeloperoxidase activity), the protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2, and eicosanoid production in colonic tissue incubation were assessed 24 and 72 h after colitis induction. Montelukast increased prostaglandin E(2) production at 24 h and tended to reduce the cyclooxygenase-2 protein expression at 72 h, but did not influence the severity of colitis. Zileuton failed to decrease the inflammatory reaction in spite of reduced leukotriene B(4) production at 72 h. The results suggest that drugs that block cysteinyl leukotriene receptors have limited potential to ameliorate acute TNBS-induced colitis, but that they exert some beneficial effects which make them capable of modulating the course of colitis.     

黄芩汤抗 TNBS诱导的小鼠溃疡性结肠炎活性研究

目的：研究黄芩汤水煎液中主要成分及对2,4,6－三硝基苯磺酸钠（ TNBS）造模balb／c小鼠的溃疡性结肠炎的作用。方法 HPLC－MS法分析水煎液成分。雄性balb／c小鼠随机分为空白对照组,TNBS模型组,柳氮磺嘧啶阳性对照组（500 mg · kg－1）,黄芩汤水煎液1,2,4 g· kg－1治疗组。 TNBS造模7 d后,研究各组小鼠的结肠病理评分、微观评分、体质量、小鼠结肠长度和血清髓过氧化物酶（ MPO）。结果与标准品对照,黄芩汤水煎液中含有复方中主要成分,黄芩汤水煎液可使TNBS造模balb／c小鼠的体质量明显增加,改善身体的一般状况和小鼠结肠黏膜的损伤,下调MPO。结论黄芩汤水煎液中含有各药物的主要成分,对TNBS诱导的小鼠溃疡性结肠炎具有较好的治疗作用。     

褪黑素对结肠炎大鼠结肠内一氧化氮合酶和环氧合酶-2含量的影响

目的　研究褪黑素对大鼠结肠炎的抗炎作用是否与诱生性一氧化氮合酶 (iNOS)和环氧合酶 2(COX 2 )有关。方法　制备大鼠乙酸性结肠炎和2 ,4 ,6 三硝基苯磺酸 (TNBS)结肠炎模型。实验设正常对照组 ,模型对照组 ,5 氨基水杨酸对照组 (10 0mg·kg- 1) ,褪黑素组 (2 .5 ,5 .0 ,10 .0mg·kg- 1) ,每天灌肠给药一次 (乙酸模型给 7d ,TNBS模型给 2 1d)。检测大鼠结肠一氧化氮 (NO) ,前列腺素 (PG)E2 ,iNOS和COX 2含量。结果　模型组大鼠结肠粘膜损伤明显 ,NO ,PGE2 ,iNOS和COX 2含量显著增加。褪黑素可减轻大鼠结肠损伤 ,明显抑制NO ,PGE2 合成并减少iNOS ,COX 2含量。结论　大鼠结肠经TNBS和乙酸致炎后iNOS ,COX 2 ,NO及PGE2合成增强 ,褪黑素通过抑制iNOS和COX 2表达减轻结肠损伤     

Ameliorative effects of 3,4-oxo-isopropylidene-shikimic acid on experimental colitis and their mechanisms in rats

The aim of the present study was to investigate the therapeutic effect and mechanism of 3,4-oxo-isopropylidene-shikimic acid (ISA) on 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis in rats. (50, 100, 200 mg/kg) was administered for 14 days, 1 day after the induction of colitis by TNBS. The colonic injury and inflammation were assessed by macroscopic damage scores and myeloperoxidase (MPO) activity. Malondialdehyde (MDA) and nitric oxide (NO) levels, and superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in plasma were measured with biochemical methods. Prostaglandin E₂ (PGE₂) level in colon was determined by radioimmunoassay. Expressions of inducible nitric oxide synthase (iNOS), cyclo-oxygenase-2 (COX-2), inhibitor kappa B-alpha (IκBα) and nuclear factor kappa B (NF-κB) p65 proteins in the colonic tissue were detected with immunohistochemistry. Enhanced colonic mucosal injury, inflammatory response and oxidative stress were observed in the animals clystered with TNBS, which was manifested as the significant increase in colon mucosal damage index, MPO activity, levels of MDA, NO and PGE₂, as well as the expressions of iNOS, COX-2 and NF-κB p65 proteins in the colonic mucosa, and the significant decrease in expressions of IκBα proteins in the colonic mucosa. However, these parameters were found to be significantly ameliorated in rats treated with ISA at given doses, especially at 100 mg/kg and 200 mg/kg. Administration of ISA may have significant therapeutic effects on experimental colitis in rats, probably due to its mechanism of antioxidation, its inhibition of arachidonic acid metabolism and its modulation of the IκBα/NF-κB p65 expression.     

Rosiglitazone, a PPARgamma ligand, modulates signal transduction pathways during the development of acute TNBS-induced colitis in rats

Recent studies have shown that peroxisome proliferator-activated receptor gamma (PPARgamma), a highly nuclear receptor expressed in the colon, may participate in the control of inflammation, especially in regulating the production of immunomodulatory and inflammatory mediators, cellular proliferation and apoptosis. In order to delve into the anti-inflammatory mechanisms and signalling pathways of PPARgamma agonists, we have studied the effects of rosiglitazone, a PPARgamma agonist on the extent and severity of acute ulcerative colitis caused by intracolonic administration of 2,4,6-trinitribenzene sulfonic acid (TNBS) in rats. The inflammatory response was assessed by gross appearance, myeloperoxidase (MPO) activity, tumour necrosis factor alpha (TNF-alpha) levels and a histological study of the lesions. We determined prostaglandin E2 production as well as the cyclooxygenases (COX)-1 and -2 expressions by immunohistochemistry and Western blotting. The nuclear factor kappa (NF-kappaB) p65 and p38 mitogen-activated protein kinase (MAPK) expression levels were also measured by Western blotting. Finally, since PPARgamma agonists modulate apoptosis, we tried to clarify its effects under early acute inflammatory conditions. Inflammation following TNBS induction was characterized by increased colonic wall thickness, edema, diffuse inflammatory cells infiltration, necrosis reaching an ulcer index (UI) of 9.66+/-0.66 cm(2) and increased MPO activity and TNF-alpha colonic levels. Rosiglitazone treatment significantly reduced the morphological alteration associated with TNBS administration and the UI with the highest dose. In addition, the degree of neutrophil infiltration and the cytokine levels were significantly ameliorated. Rosiglitazone significantly reduced the rise in the prostaglandin (PG) E(2) generation compared with TNBS group. The COX-1 levels remained stable throughout the treatment in all groups. The COX-2 expression was elevated in TNBS group; however rosiglitazone administration reduced the COX-2 overexpression. A high expression of NF-kappaB p65 and p38 MAPK proteins appeared in colon mucosa from control TNBS-treated rats; nevertheless, PPARgamma agonist treatment drastically decreased them. There were no significant changes in apoptosis after rosiglitazone treatment when compared to TNBS group. In conclusion, rosiglitazone seems to modulate the acute colitis through NF-kappaB p65 and p38 MAPK signalling pathways.     

Nafamostat mesilate attenuates colonic inflammation and mast cell infiltration in the experimental colitis

Serine proteases are important in the pathogenesis of intestinal inflammation. Recent studies have shown that nafamostat mesilate (NM) can inhibit the colonic mucosal inflammation induced by TNBS in rats. The aim of this study was to investigate the anti-inflammatory effects of NM on a DSS-induced colitis. Colitis was induced in female BALB/c mice by 5% dextran sulfate sodium (DSS) for 6 days. NM (2 or 20mg/kg body weight) was orally administered once a day for 6 days during treatment of the mice with DSS. The inflammatory response of the colon was assessed 1 week after DSS treatment. NM at a high dose, but not at a low dose significantly decreased disease activity index (DAI) and myeloperoxidase (MPO) induced by DSS. Furthermore, NM (20mg/kg) inhibited the production of tumor necrosis factor (TNF)-α, cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in the colonic tissues treated with DSS. The increase in chymase activity by DSS treatment was also attenuated by the administration of NM (20mg/kg). NM (20mg/kg) significantly decreased the colonic mucosal injury and the infiltrated mast cell number induced by DSS. These results indicate that NM might inhibit the colonic inflammation through inhibition of both chymase activity and mast cell infiltration in colon tissues of DSS-induced colitis.     

肠包衣地塞米松脂质体壳聚糖胶囊对炎性结肠组织MPO活性的影响

目的评价肠包衣地塞米松(DSP)脂质体冻干剂壳聚糖胶囊对大鼠炎性结肠组织髓过氧化酶(MPO)活性的影响。方法用2,4,6-三硝基苯磺酸钠(TNBS)诱导大鼠结肠炎,建立反应结肠炎症程度的结肠组织MPO浓度的测定方法,观察口服各种DSP制剂对MPO的抑制程度。结果TNBS灌肠后d 5时MPO达到最高值;各种DSP制剂均有降低TNBS诱导的实验性大鼠结肠炎结肠组织MPO的效果,但DSP脂质体壳聚糖胶囊具有最好的抑制作用。结论肠包衣DSP脂质体冻干剂壳聚糖胶囊在治疗结肠炎中可能具有较大的应用前景,值得进一步开发研究。     

Vascular contribution of adrenomedullin to microcirculatory improvement in experimental colitis

The effect of adrenomedullin (AM), a peptide that has demonstrated vasodilatory activity, was studied in the colon and small mesenteric arteries of rats in a chronic model of inflammatory bowel disease. AM (50 ng/kg/day) was administered i.p. daily, starting 24h after trinitrobenzensulfonic acid (TNBS, 30 mg) instillation. After 14 days, rats were sacrificed, colons were macroscopically analyzed and biochemical parameters (myeloperoxidase activity, cytokines, cyclooxygenase-2 (COX-2) as well as inducible nitric oxide synthase (iNOS) expression) were determined. Vascular function of small mesenteric arteries was assessed by addition of phenylephrine (10?? to 10?? mol/L) and participation of COX and NOS pathways was also evaluated by using different inhibitors: indomethacin, NS-398, L-NNA, and 1400 w. Chronic AM treatment significantly reduced colonic macroscopic damage and inflammation markers. TNBS instillation induced COX-2 and iNOS expressions in colon and small mesenteric arteries; AM treatment decreased COX-2 expression only in microvessels from rats with colitis. An attenuation of phenylephrine-induced contraction was detected in small mesenteric arteries from both TNBS and AM-treated rats. COX and NOS inhibitors altered the contractile ability of phenylephrine in small mesenteric arteries from TNBS rats, suggesting the involvement of COX-2 and iNOS derived factors in the deleterious effect of TNBS on vascular reactivity; AM administration was able to reduce such alteration. Finally, treatment with the peptide significantly reduced colonic nitric oxide (NO) levels, without affecting plasma concentration. In conclusion, AM showed beneficial effects in the restoration of vascular function through the regulation of vasoactive products derived from COX-2 and iNOS.     

大鼠溃疡性结肠炎模型的实验研究

目的对不同剂量的三硝基苯磺酸（ＴＮＢＳ）引起的大鼠溃疡性结肠炎（ＵＣ）模型进行观察和评价。方法采用一次性直肠注入大鼠ＴＮＢＳ（２５～１５０ｍｇ·ｋｇ－１）的３０％乙醇溶液，引起慢性炎症性肠疾病（ＩＢＤ），３ｗｋ后外死动物对各剂量下动物结肠的重量、髓过氧化物酶（ＭＰＯ）活性及组织形态学变化进行观察和评价。结果ＴＮＢＳ在１００～１５０ｍｇ·ｋｇ－１剂量下引起的ＵＣ肠壁明显增厚，炎症和溃疡至少维持７ｗｋ时间，ＭＰＯ活性值显著性升高，组织学检查发现粘膜及粘膜下层有大量中性粒细胞及淋巴细胞、巨噬细胞、纤维细胞浸润，肉芽组织及隐窝脓肿形成，５０ｍｇ·ｋｇ－１剂量时有一较轻度的损伤。２５ｍｇ·ｋｇ－１时对结肠的重量、ＭＰＯ活性及损伤指数都没有显著性改变（Ｐ＞０．０５）。结论用ＴＮＢＳ引起大鼠实验性ＵＣ，其溃疡和炎症维持一较长时间，这一病理特征为炎症性疾病防治药物的研究提供了条件；本模型的最佳剂量为１００ｍｇ·ｋｇ－１左右     

葡萄籽原花青素对复发性结肠炎大鼠血清抗氧化能力及NO含量的影响

目的：观察葡萄籽原花青素（GSPE）对复发性结肠炎大鼠血清抗氧化能力及NO含量的影响,初步探讨葡萄籽原花青素治疗复发性结肠炎的作用机制。方法：直肠给予雄性Wistar大鼠80mg/kg2,4,6-三硝基苯磺酸（TNBS）/50%乙醇溶液复制结肠炎模型,在第16天时,用30mg/kgTNBS/50%乙醇溶液诱导结肠炎复发的模型。大鼠第二次致炎24h后,分别应用GSPE低、中、高剂量（100、200、400mg/kg）灌胃对其进行治疗,并以柳氮磺吡啶（SASP,500mg/kg）作为阳性对照。连续给药7d后处死所有大鼠,取结肠标本评价结肠湿重指数,生化法检测血清中髓过氧化物酶（MPO）、超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-Px）和一氧化氮合酶（iNOS）活力及丙二醛（MDA）、谷胱甘肽（GSH）和NO含量。结果：与模型对照组比较,GSPE各剂量组大鼠体重下降程度较轻（P〈0.05或P〈0.01）,结肠湿重指数明显降低（P〈0.05或P〈0.01） 大鼠血清中MPO和iNOS活力及MDA和NO含量均明显降低（P〈0.05或P〈0.01） 大鼠血清中SOD和GSH-Px活力及GSH含量明显升高（P〈0.05或P〈0.01）。结论：GSPE可能通过提高复发性结肠炎大鼠血清抗氧化能力,抑制NO生成,来减轻复发性结肠炎炎症反应。     

The effect of heparin on trinitrobenzene sulphonic acid-induced colitis in the rat

Background:

Reduced blood coagulability seems to protect against inflammatory bowel disease; pilot studies using heparin in patients with inflammatory bowel disease have reported positive results.

Aim:

To evaluate the effects of heparin treatment on microangiographic and on inflammatory parameters in experimental colitis, induced by trinitrobenzene sulphonic acid (TNBS)-ethanol.

Methods:

Four groups of rats: (i) controls (saline enema), TNBS-induced colitis with (ii) sham treatment (saline, s.c.), (iii) dexamethasone (0.25 mg/kg/day s.c.) and (iv) heparin (500 U/kg t.d.s., s.c.). Microangiography was performed 2 and 4 days after colitis induction. Partial thromboplastin time, colonic wet weight, macroscopic damage score and mucosal myeloperoxidase (MPO) activity were determined at day 4.

Results:

TNBS-induced colitis caused a reduction in visible bowel wall vessels, which was prevented by heparin (P < 0.05) but not by steroids. The macroscopic damage scores and colon wet weights were similar in all colitis groups. Compared to untreated colitis the MPO activity in heparin-treated animals was of borderline significance.

Conclusions:

Heparin treatment improved microangiographic features and reduced inflammation to a certain degree. Steroids delayed development of colon hypoperfusion, but were ineffective on MPO activity. It remains to be determined if the observed effects are due to the antithrombotic activity of heparin or to an anti-inflammatory action.