肠易激综合征大鼠内脏敏感性异常与结肠及中枢神经系统5-HT和c-fos表达的关系

Visceral sensitivity and expression of 5-hydroxytryptamine and c-fos in the enteric and central nerves syndrome in the rat model with irritable bowel syndrome

目的研究便秘型肠易激综合征(C-IBS)大鼠模型对直肠球囊扩张的内脏敏感性改变和肠神经系统及中枢神经系统5-羟色胺(5-HT)、c-fos的分布和异常表达。方法C-IBS大鼠模型组应用冰水灌胃方法建立(A组,n=10)和正常对照大鼠(B组,n=10)。所有大鼠给予直肠内球囊扩张,检测球囊扩张引起腹部收缩反射的最小容量阈值及1.0 mL扩张容量时腹部收缩反射(AWR)的次数。结肠、回盲部肌间神经丛及下丘脑、前扣带回5-HT和c-fos表达应用免疫组织化学染色及计算机图像分析系统半定量进行分析。结果直肠内球囊扩张时,A组引起腹部收缩的最小容量阈值略高于B组,无明显统计学差异(P>0.05),直肠球囊扩张体积1.0 mL时A组3 min AWR低于B组(10.3±3.3vs18.3±5.5,P<0.05)。A组结肠、回盲部5-HT、c-fos阳性肌间神经丛的数目及OD值均明显高于B组(P<0.05);A组下丘脑及前扣带回5-HT、c-fos阳性神经组织面积及OD值也明显高于B组。结论C-IBS大鼠模型存在对直肠球囊扩张的内脏敏感性异常,肠神经系统及中枢神经系统5-HT、c-fos的异常表达可能参与C-IBS大鼠内脏敏感性异常的调节。

Objective To study the visceral sensitivity by the rectal balloon distension and expression of 5- hydroxytryptamine（5-HT） and c-los in the enteric nerves system（ENS） and central nerves system（CNS） of the rat model with constipation predominant irritable bowel syndrome （C-IBS）. Methods The rat model was established by intragastric injection with ice-cold water （0 -4℃ ）. The visceral sensitivity was evaluated using the rectal perception thresholds and the number of abdominal withdrawal reflexes（AWR） which were induced by rectal balloon distention in model group （ group A, n = 10） and control group （ group B,n = 10）. The expressions of 5-HT and c-los in the myenteric nerve plexus of colon and neuron of hypothalamus and anterior cingulate gyrus were showed by immunohistochemical staining and analyzed semi-quantitatively by computerized color image analyzer using the immunoreactive areas, numbers and opacity density （OD） respectively. The statistical difference of the OD and immunoreactive areas between two groups was examined by t-test. Results The perception threshold to rectal balloon distention in group A was slightly higher than that of group B. But there was no significant difference （P 〉 0.05 ）. The number of AWR was much lower in group A than in group B （10.3 ± 3.3 vs 18.3 ± 5.5,P 〈 0.05 ）. Immunoreactive area, numbers and OD of 5-HT and c-los posi- tive neurons and firbes of ENS and CNS in group A were significantly higher than those of group B （P 〈 0.05 ）. Conclusions The model of C-IBS has a decreased visceral sensitivity to the rectal balloon distention. The increased expression of 5-HT and c-los in ENS and CNS are probably involved in the process.