大鼠肠道高敏性模型的建立及其内脏敏感性评估

Establishment of a rat model of gut hypersensitivity and for evaluation of visceral sensitivity

目的 内脏高敏感性是肠易激综合征 (IBS)的重要病理生理特征之一 ,该文旨在建立内脏高敏性动物模型 ,并用两种方法验证该模型的有效性。方法 取出生后 8～ 2 1d的大鼠 ,每天给予直肠内醋酸刺激 ,分别在出生后 6、8及 10周 ,对这些成年后的大鼠进行直肠扩张 ,评估其腹部收缩反射(AWR)阈值 ;并在出生 12周后测定大鼠腹壁肌电活动 ,验证敏感性有无异常改变。结果 与新生期生理盐水刺激组 (NS组 )和成年醋酸刺激组 (AA组 )相比 ,直肠扩张时 ,新生期醋酸刺激组大鼠 (NA组 )腹部抬高和背部拱起的容量阈值显著降低 (P值均 <0 .0 1) ;0 .5、0 .8、1.2ml扩张容量下腹壁肌电活动明显增强 (P分别 <0 .0 1,<0 .0 5和 0 .0 5 )。结论 新生期肠道内的慢性刺激 ,可以在成年后引起慢性内脏敏感性增高 ,而肠黏膜未见异常病理改变 ,符合IBS的基本特征。

Objective Visceral hypersensitivity is an important feature of irritable bowel syndrome (IBS). This investigation was to establish an animal model of visceral hypersensitivity associated with IBS, and to test its effectiveness by two different ways. Methods The model was established by intrarectal administration of acetic acid daily in the neonatal rats between postnatal 8 and 21 days. The threshold of abdominal withdrawal reflex(AWR) was evaluated during rectal distension at postnatal 6,8 and 10 weeks respectively, and the changes of rectal sensitivity were identified by the abdominal electrical activity measured at postnatal 12 weeks. Results In contrast to neonatal rats subjected to saline intrarectally (NS group) and adult rats subjected to acetic acid intrarectally (AA group), neonatal rats subjected to acetic acid intrarectally(NA group) showed a significant decrease(P<0.01) in the volume threshold of abdomen lifting and body arching during rectal distension; there was a significant increase of abdominal electrical activity responding to 0.5,0.8 and 1.2 ml distension volume compared with control rats(P<0.01, P<0.05 and P<0.05, respectively). Conclusions Chronic rectal irritation in the neonatal rats may leads to chronic rectal hypersensitivity in the adulthood in the absence of identifiable rectal pathological changes, which conforms to IBS.