5-HT_(2B)受体在不同亚型肠易激综合征模型大鼠发病中的作用

Effect of 5-HT_(2B) receptor on the pathogenetic mechanism of irritable bowel syndrome subgroups in rat models

目的:观察5-HT2B受体在不同亚型肠易激综合征(irritable bowel syndrome,IBS)模型大鼠中表达的差异。方法:45只大鼠随机分为腹泻型IBS组(D-IBS组)、便秘型IBS组(C-IBS组)和对照组,每组15只。乙酸加束缚应激法制备D-IBS模型,冰水灌胃法制备C-IBS模型,对照组不予任何处理。从大鼠粪便湿重、含水量、结直肠扩张(CRD)刺激下腹外斜肌放电活动和结肠组织HE染色四个方面来评估造模是否成功。免疫组化法观察各组大鼠结肠组织中5-HT2B受体的分布差异;Western blot法及逆转录PCR法检测各组大鼠结肠组织中5-HT2B受体表达的不同。结果:与对照组相比,D-IBS组大鼠粪便湿重和含水量均明显增高(P<0.05),而C-IBS组降低(P<0.05);模型组大鼠腹外斜肌放电幅值,在压力为40、60 mmHg的CRD刺激下,均较对照组明显增加,且D-IBS组高于C-IBS组(P<0.05);模型组结肠组织中均无炎症产生,从以上四方面可以看出造模成功。5-HT2B受体主要分布在结肠肌间神经丛、纵肌层和黏膜层。D-IBS组结肠组织中5-HT2B受体蛋白及mRNA表达量显著高于对照组(P<0.05),而C-IBS组低于对照组(P<0.05)。结论:5-HT2B受体可能参与了不同亚型IBS的发病。

Objective：To investigate the effect of changes in 5-HTEB receptor on the pathogenetic mechanism of irritable bowel syn- drome （IBS） subgroups in rat models. Methods：Forty-five SD rats were divided into the D-IBS group, C-IBS group and control group. The D-IBS model was established in rats by intracolonic instillation of acetic acid and by restraint stress. The C-IBS model was estab- lished in rats by gastric instillation of 0-4℃ cool water daily for 14 days. The control group was also made. Weight and water content of the feces expelled by the rats were calculated. Abdominal contractions induced by distension of a colonically inserted balloon （0- 60 mmHg） were recorded in rats by implanting electrodes in the abdominal external oblique muscle. Histological analysis of colonic tissue was performed. The distributions of 5-HTEB receptor in colon tissues of the D-IBS, C-IBS and control groups were detected by immun0histochemistry. The expressions of 5-HTEB receptor protein and mRNA in colon tissues in the D-IBS, C-IBS and control group were detected by Western blot and reverse transcription PCR, respectively. Results：The wet weight and water content of the feces ex- pelled by the rats in the C-IBS were significantly lower than those in the control group （P 〈 0.05） ,while those of the D-IBS group were higher than the control group （P 〈 0.05）. The amplitude of the abdominal muscle contraction was higher in the D-IBS group and C-IBS group compared with the control group when the balloon was distended at the pressure of 40 and 60 mmHg： The amplitude of the contraction in the D-IBS group was higher than the C-IBS group （P 〈 0.01 ）. Histological analysis of the colon showed no colonic inflammation in any group. These aspects suggested that IBS subgroups were successfully made. Immunohistochemistry demonstrated that the 5-HTEB receptor was mainly localized in the myenteric nerve plexus,longitudinal muscle and colon mucosa. Western blot and reverse transcription PCR analyses showed that the expressions of 5-HT2B receptor protein and mRNA in the D-IBS group were higher than those in the control group （P 〈 0.05）;however,the levels of 5-HTEa receptor protein and mRNA in the C-IBS group were lower than those in the control group（P 〈 0.05）. Conclusion：The results indicate that 5-HTEa receptor plays a role in the pathogenetic mechanism of the IBS subgroup.