新生期结肠刺激及性别对幼鼠内脏痛敏感性的影响

EFFECT OF NEONATAL COLORECTAL IRRITATION AND GENDER ON VISCERALGIA SENSIBILITY IN DEVELOPMENTAL RATS

目的: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及其性别差异。方法:8日龄新生SD大鼠随机分成实验组和对照组,每组16只;实验组新生鼠在出生第8天开始给予CI,每日1次,连续7天;对照组则不给予CI。到6周龄时进行内脏敏感性测定。采用腹壁撤退反射(AWR)评分的测定作为不同的扩张压力下结直肠疼痛反应指标,评估肠道痛觉敏感性。结果:6周时两组大鼠体重无显著差异;两组大鼠降结肠均未见明显病理组织损伤;随着CRD压力增加,两组大鼠AWR评分逐渐增加;在控制幼鼠性别影响因素后,当CRD压力分别为20mm-Hg、40mmHg及60mmHg时,实验组AWR评分的边缘估计均值均高于对照组,差别有显著意义。在控制组别等影响因素后,当CRD压力分别为60mmHg、80mmHg时,雌性幼鼠AWR评分的边缘估计均值均高于雄性幼鼠,差别有显著意义;当CRD压力为20mmHg、40mmHg时,虽然雌性幼鼠AWR评分的边缘估计均值仍高于雄性幼鼠,但差别无显著意义。结论:在新生期进行持续的结直肠刺激能造成幼鼠痛阈下降,出现慢性内脏痛觉高敏感性,并且这种高敏感性具有性别差异。

Objective： To investigate the effect of detrimental colorectal irritation （CI） in neonatal period on visceralgia sensitivity and its gender differences in developmental rats. Method： Neonatal Sprague- Dawley rats （8 days old） were divided into experiment group （n = 16） and control group （n = 16） randomly. Rats in the experiment group were treated with colorectal irritation once a day during 7 consecutive days, but the control rats were handled without colorectal irritation. On the 6th week, the visceral sensitivity of all experimental rats was estimated. The abdominal withdrawal reflex （AWR） score was measured to evaluate the bowel sensitivity as the markers of colorectal painthl responding. Results：There were no significant differences in weight between two groups. No obvious histopathological changes were observed in both groups of rats in the gross and under microscope of descending colon. After controlling the effect of gender and weight, the 95% confidence interval of the AWR score was increased gradually with the CRD pressure from 20 to 60 mmHg in both groups, the differences were significant. After controlling the effect of group difference, the 95% confidence interval of the AWR scores were higher in the female young rats than those in males when the CRD pressure was 60 mmHg and 80 mmHg, the differences were significant. Though the 95% confidence interval of the AWR scores were higher in the females than those in males when the CRD pressure was 20 mmHg and 40 mmHg, the differences were not significant. Conclusion： The persistent stimulation of CI in neonatal phase results in low pain threshold and high chronic visceral sensitivity, this hyperalgesia was gender differences. While histological change was not found in colorectal tissue.