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目的探索建立幼鼠内脏痛觉高敏感性模型的适宜条件和幼鼠内脏痛觉的电生理学评价方法,探讨新生期伤害性结直肠扩张刺激(CI)对幼鼠内脏痛觉敏感性的影响。方法8日龄新生SD大鼠随机分为实验组和对照组,每组16只。实验组在出生第8天开始予CI,1次/d,连续7d;对照组不予CI。随后2组大鼠常规饲养至6周龄时进行内脏敏感性测定。采用腹外斜肌放电法测量其结直肠在不同扩张压力下的腹外斜肌放电幅度,评估幼鼠的内脏痛觉敏感性。采用重复测量方差分析进行统计学分析,检验水准α=0.05。结果随着结直肠扩张(CRD)压力的增加,2组幼鼠腹外斜肌放电波幅逐渐增加。在4、6kPa的CRD压力下,实验组幼鼠腹外斜肌放电幅值均显著高于对照组(Pa<0.05);当CRD为2kPa低扩张压刺激和8、10kPa高扩张压刺激时,2组腹外斜肌放电波幅均无显著性差异(Pa>0.05)。2组幼鼠降结肠未见明显病理组织损伤。结论新生期进行持续的CI可造成幼鼠痛阈下降,出现慢性内脏高敏感性,同时无明显组织学改变,为研究儿童腹痛相关性功能性胃肠病的一种较理想动物模型;与行为学评价方法相比,电生理评价方法可定量检测,能较为客观的反映动物内脏痛觉的致敏效应。
Objective To explore the suitable conditions of visceral hyperalgesia rat model and electrophysiological evaluation of visceral hyperalgesia in young rats and to explore the effect of nociceptive colorectal distention stimulation (CI) in neonatal rats on the visceral hyperalgesia. Methods 8-day-old newborn SD rats were randomly divided into experimental group and control group, with 16 rats in each group. The experimental group was given CI on the 8th day of birth, once a day for 7 days, while the control group was not given CI. Then two groups of rats routine feeding to 6 weeks of age for visceral sensitivity determination. Abdominal oblique muscle discharge method was used to measure the discharge amplitude of the extracorporeal oblique muscle of the colorectal under different dilatation pressures to evaluate visceral hyperalgesia in young rats. Statistical analysis was performed using repeated measures ANOVA with a test level of α = 0.05. Results With the increase of colorectal distension (CRD) pressure, the amplitude of extracorporeal oblique muscle discharge increased gradually in two groups of rats. Under the CRD pressure of 4 and 6 kPa, the amplitude of abdominal oblique muscle discharge in the experimental group was significantly higher than that of the control group (Pa <0.05). When the CRD was 2 kPa low dilatation pressure and 8,10 kPa high dilatation pressure, There was no significant difference in discharge amplitude between two groups (Pa> 0.05). 2 groups of rats descending colon no obvious pathological tissue injury. CONCLUSION: Continuous CI in neonatal period can reduce the pain threshold of young rats with chronic visceral hypersensitivity and no obvious histological changes, which is an ideal animal model for studying abdominal pain-related functional gastrointestinal disorders in children. Compared with behavioral Compared with the evaluation method, the electrophysiological assessment method can be quantitatively detected, which can objectively reflect the sensitization effect of visceral pain in animals.