Beagle犬急性放射性肠炎模型的建立及评价

Establishment and evaluation of acute radiation enteritis model in Beagle dogs

目的建立急性放射性肠炎Beagle犬模型,为放射性肠炎治疗药物的开发与评价提供新模型。方法将30只Beagle犬按体重及性别随机分为正常组、不同放射强度模型组[采用钴60辐照机(γ射线)单次腹盆腔局部照射,强度为60 Gy·h^-1,分别连续照射8、10和12 min]及药物验证组(60 Gy·h^-1,连续10 min+美沙拉嗪肠溶片62.5 mg·kg^-1,1次·d^-1,连续7 d),每组6只动物,雌雄各半。观察照射后Beagle犬体重、摄食量、排便情况及自主活动情况,造模后第7日安乐死剖检动物,ELISA法检测回肠匀浆细胞因子白介素(IL)^-1β、肿瘤坏死因子(TNF)-α含量,HE染色检查回肠组织病理学改变并测定小肠绒毛高度和隐窝深度,免疫组化法测定回肠组织中增殖细胞核抗原(PCNA)的表达水平。结果模型组(8 Gy和10 Gy)动物体重降低,摄食量减少,自主活动减少,出现糊状便或黏液脓血便,模型组(12 Gy)动物在4 d内全部死亡;模型组(10 Gy)动物回肠组织镜下观察可见黏膜层小片状脱落,固有层腺体轮廓欠完整,结构紊乱,排列稀疏,黏膜下大量炎细胞浸润,血管充血明显,多灶溃疡形成。模型组绒毛高度及隐窝深度均显著小于正常组(P <0.01);细胞因子IL^-1β、TNF-α的含量较正常组显著增加(P <0.05或P <0.01);PCNA表达水平较正常对照组显著降低(P <0.05或P<0.01);美沙拉嗪肠溶片组能显著降低细胞因子IL^-1β、TNF-α的含量,增加回肠组织绒毛高度及隐窝深度,同时增加PCNA阳性表达水平。结论钴60(γ射线)单次腹盆腔局部照射能诱导Beagle犬急性放射性肠炎,其临床表现及病理改变与临床放射性肠炎相似,其中造模强度以累积剂量为10 Gy/只(60Gy·h^-1,连续照射10 min)为佳。

Objective To establish a Beagle dog model of acute radiaction enteritis of and provide a new and reliable model for the evaluation of drugs for radiation enteritis. Methods Totally 30 Beagle dogs were randomly divided into 5 groups according to the weight and gender, 6 animals in each group, half male and half female. The normal control group, three model groups with different radiation intensities(cobalt 60, gamma ray single abdomial pevic irradiation, partial light, intensity of 60 Gy·h^-1 for 8, 10, and 12 min continuous exposure) and a drug validation group(60 Gy·h^-1 for 10 min and mesalazine enteric-coated tablets 62.5 mg·kg^-1, once daily for 7 days). Body weight, food consumption, defecation and autonomous activity were observed after irradiation. All animals were euthanized after modeling. Ileum tissue was collected to detect the content of cytokine interleukin(IL)^-1β, tumor necrosis factor(TNF)-α with ELISA. Histopathological changes was detected by HE staining, with the villus height and crypt depth of small intestinal were measured. The expression level of PCNA(Proliferating nuclear antigen) was detected by immunohistochemical staining. Results The results showed a decrease in body weight, food intake and autonomic activity and the sign of mushy stools or mucous bloody stool in model group(8 Gy and 10 Gy). Animals in the model group(12 Gy) were dead within 4 days. Under the microscope, mucosa layer was found flaking off visibly, structure disordered and messily arranged in the mucosa ileum. Many inflammatory cells, congested blood-vessels, and formation multifocal ulcer were observed in the model group(10 Gy). Both the villus height and crypt depth were significantly lower than that of the normal group(P < 0.01). The content of cytokine interleukin(IL)^-1β and TNF-α was significantly higher than that of the normal group(P < 0.05 or P < 0.01). The expression of PCNA was significantly lower than that of the normal group. Mesalazide enteric-coated tablets significantly reduced the content of cytokine IL^-1β and TNF-α, increase the villus height and crypt depth of the ileum tissue and the expression of PCNA. Conclusion Cobalt 60(gamma rays) for single local abdominal and pelvic irradiation may successfully induce acute radiation enteritis of Beagle dog, with clinical characteristics and pathological changes similar with clinical radiation enteritis. The modeling intensity is ideal with cumulative dose of 10 Gy(60 Gy·h^-1 for 10 min).