第Ⅲ组亲代谢型谷氨酸受体在内脏高敏性大鼠结肠中的表达

目的 探讨第Ⅲ组亲代谢型谷氨酸受体mGluR4、mGluR7、mGluR8在内脏高敏性大鼠结肠中的表达变化。方法 12只SD雄性幼鼠分为母婴分离(neonatal maternal separation, NMS)组和对照组(normal control, NC)组。利用结直肠扩张(colorectal distention, CRD)刺激下的腹壁回缩反射(abdominal withdrawal reflex, AWR)评分和腹壁肌电活动(electromyography, EMG)检验模型有效性；应用RT-PCR、Western印迹法和免疫组化检测第Ⅲ组亲代谢型谷氨酸受体mGluR4、mGluR7、mGluR8在模型组和对照组大鼠结肠中的表达变化。结果 在不同压力CRD刺激下,NMS组大鼠的AWR评分(P＜0.01)和腹壁肌电活动(P＜0.05)明显高于NC组；NMS组大鼠结肠中第Ⅲ组亲代谢型谷氨酸受体mGluR4、mGluR7、mGluR8的mRNA(P＜0.01,P＜0.05,P＜0.01)和蛋白水平表达(积分光度值integrated density, ID)(P＜0.05,P＜0.01,P＜0.01)分别高于相对应NC组的表达；NMS组mGluR4、mGluR7、mGluR8的阳性表达率明显高于NC组。结论 第Ⅲ组亲代谢型谷氨酸受体mGluR4、mGluR7、mGluR8在内脏高敏性大鼠结肠中的表达明显升高,肠易激综合征(irritable bowel syndrome, IBS)发病可能与第Ⅲ组亲代谢型谷氨酸受体相关。
Objective To study the expression of group Ⅲ metabotropic glutamate receptors(Ⅲ mGluRs) in intestine of visceral hypersensitivity rats. Methods Twelve male neonate SD rats were randomly assigned into NMS group and NC group, the neonatal maternal separation model was induced in NMS group. The scores of abdominal withdrawal reflex(AWR) and electromyography(EMG) by colorectal distention(CRD) were used to test the model. The expression of Ⅲ mGluRs mRNA and proteins in intestine of visceral hypersensitivity rat was observed with Real time PCR, Western blot and immunohistochemistry, respectively. Results The scores of AWR and EMG activity in NMS group were higher than those in NC group(P＜0.01 and P＜0.05). The mRNA and protein expressions of mGluR4, mGluR7 and mGluR8 in NMS group were significantly higher than those in NC group(P＜0.01 or P＜0.05)； the positive rates of mGluR4, mGluR7 and mGluR8 in NMS group were significantly higher than those in NC group. Conclusion The expression of Ⅲ group metabotropic glutamate receptors in the intestine of visceral hypersensitivity rats is significantly up-regulated, indicating that episode of irritable bowel syndrome is related to Ⅲ group metabotropic glutamate receptors