食管酸灌注对内脏高敏感模型大鼠中枢神经系统Fos表达的影响

Effects of esophageal mucosai acid exposure on expression of c-fos protein in central nervous system in ovaibumin sensitized rats

目的观察在内脏高敏感状态下食管酸灌注对中枢神经系统(CNS)各部位Fos蛋白表达的影响,以初步明确CNS参与内脏高敏感性应答和调控的具体部位及中枢传导通路的变化。方法健康SD大鼠36只,随机分为5组。A组：正常对照组6只；B组：0．9%氯化钠溶液对照组7只；C组：食管酸灌注组8只；D组：卵清蛋白(OVA)致敏组7只；E组：OVA+食管酸灌注组8只。采用腹腔注射鸡OVA基础致敏联合食管酸灌注的方法建立食管内脏高敏感性大鼠模型；采用免疫组化方法和显微图像分析等技术研究在生理条件、内脏高敏状态下食管酸灌注后CNS各部位的Fos蛋白激活模式的差异。结果鸡OVA致敏联合食管酸灌注组被激活了一个复杂而广泛大脑网络,其在额顶皮质、岛叶、扣带皮质、中央杏仁核、Kol—liker Fuse核、疑核、臂旁核、下丘脑室旁核、丘脑室旁核、三叉旁核、孤束核、最后区、延髓网状核等核团Fos样免疫活性(FLI)神经元的数目均显著高于其余各组(P＜0．05),但在迷走神经背核、下丘脑视上核、中脑导水管周围灰质、腹外侧眶皮层的FLI神经元数量,与食管酸灌注组比较则无明显改变(P＞O．05)。且该组大鼠的中央杏仁核、臂旁核、室旁核、三叉旁核、孤束核的FLI阳性产物的平均吸光度(A)值亦较其余各组明显增高(P＜0．05)。结论腹腔注射鸡OVA基础致敏对食管酸灌注诱导的CNS内Fos蛋白表达有活化作用,提示内脏高敏感状态可导致CNS不同核团神经元功能发生不同程度的障碍,CNS整合、处理食管感觉传人信息功能异常。

Objective To investigate the distribution of neurons expressing Fos protein in central nervous system （CNS） following esophageal mucosal acid exposure, and to map the contribution of specific brain areas in sensitizing responsivity and emphasize the coding change of CNS to the esophageal acid stimulation. Methods Thirty-six healthy Sprague Dwley rats were randomly divided into five groups. Group A （n = 6） was normal group of home cage control animals to which no stimulation was given. Group B （n=7） was saline group which received esophageal perfusion with normal saline solution （0. 9% NaCl）. Group C （n = 8） was treated with esophageal mucosal acid exposure containing 0.1 mol/L HCI. Group D （n=7） was sensitized by ovalbumin. Group E （n = 8） received basal ovalbumin-sensitization plus esophageal mucosal acid exposure. The rat model of esophageal visceral hypersensitivity was estab lished by the basic ovalbumin-sensitization combined with intra-esophageal mucosal acid exposure. The neuronal expressions of c los proto-oncogene were detected with immunohistochemical counter staining and computerized color image analyzer under various conditions. Results The rats in model group with basic ovalbumin sensitization plus esophageal acid perfusion initiated a high density expression of c-los immunoreactive（Fos IR） neurons in muhineuronal networks. A significantly higher number of Fos positive neurons was found in the model group than those in the corresponding regions of other groups （P 〈 0.05 ）in the following brain areas： frontal and parietal cortex, insular cortex, cingulated cortex, central amyg daloid nucleus, the Kolliker Fuse nucleus, the nucleus ambiguus, parabrachial nucleus, hypothalamic paraventricular nucleus, paraventricular thalamic nucleus, paratrigeminal nucleus, the nucleus of solitary tract, area postrema, reticular nucleus of medulla, whereas no significant difference was found in the dorsal motor nucleus of the vagus, supraoptic nucleus, periaqueductal gray matter or orbital part of infe rior frontal gyrus. The values of Fos IR neurons were also increased in the central amygdala, parabrachi al nucleus, paraventricular nucleus, the paratrigeminal nucleus and NTS in the model group than that in the corresponding regions of other groups （P 〈0.05）. Conclusion The basic ovalbumin-sensitization fa cilitated dramatically the c-los expression evoked by esophageal acid perfusion, suggesting that visceral hypersensitivity induced by ovalbumin may alter cortical reactivity processing of esophageal acid stimula tion in brain areas.