听觉剥夺和耳蜗内电刺激引起幼鼠听觉通路bdnf和c-fos基因及蛋白改变

目的 观察耳聋幼鼠及耳聋后单耳植入电极电刺激后，其听皮层和下丘、耳蜗核三个部位的脑源性神经营养因子(brain-derived neurotrophic factor, bdnf)、c-fos基因、蛋白表达水平的变化情况。方法 将66只SD幼鼠随机分为6组，每组11只，分别为注射药物后耳聋4周组(A1组)及对照组(A2组)，耳聋6周组(B1组)和及对照组(B2组)，注射药物后3周接受耳蜗内电刺激组(C组)，5周接受耳蜗内电刺激组(刺激时间为1周，D组)。于幼鼠颈背部、两侧下腹部皮下注射庆大霉素(总量为350mg/kg)，0.5h后于相同部位注射呋塞米(总量为200mg/kg)。分别于注射药物后不同时间取听皮层、下丘及耳蜗核三个部位的组织行实时荧光定量PCR及免疫组织化学方法，观察bdnf及c-fos基因及蛋白表达的变化。结果 A1组在听皮层、下丘及耳蜗核部位的bdnf及c-fos基因及蛋白表达均较A2组上升，较C组下降(P＜0.05)。B1组在听皮层、下丘及耳蜗核部位bdnf及c-fos基因及蛋白表达均较B2组和D组下降(P＜0.05)。各组之间的差异均有统计学意义。结论 听觉剥夺可导致幼鼠听皮层、下丘和耳蜗核部位的bdnf及c-fos基因及蛋白早期表达增多，而晚期表达下降。耳蜗植入电极电刺激可导致幼鼠听皮层、下丘和耳蜗核部位的bdnf及c fos基因及蛋白表达增多。bdnf及c-fos基因及蛋白表达的动态变化反映三个部位的可塑性变化。

Variations of bdnf and c-fos and their proteins in the auditory pathway induced by auditory deprivation and intracochlear electrical stimulation in infant rats

Objective o observe variations of the brain-derived neurotrophic factor (bdnf) and c-fos and their proteins induced by auditory deprivation and intracochlear electrical stimulation in the auditory cortex, inferior colliculus and cochlear nucleus in infant rats. Methods Sixty-six SD infant rats were randomly divided into 6 groups：the 4-week group(group A1), the 6-week group (group B1)with injection of ototoxic drug and their homologus control group(group A2，B2), the 3-week group(group C), and the 5-week group(group D)with injection of ototoxic drug with intracochlear electrical stimulation for one week. Each group consisted of 11 rats. Gentamicin sulphate (350mg/kg body weight) and frusemide (200mg/kg body weight) were subcutaneously injected in the skin folds on the lateral abdominal side and the dorsal neck area. Expressions of mRNAs and proteins encoded by bdnf and c-fos were detected by real-time PCR and immunohistological staining. Results Real-time PCR and immunohistochemistry revealed that expressions of mRNAs and proteins encoded by bdnf and c-fos significantly increased in group A1 as compared to group A2, and decreased as compared to group C (P＜0.05), in the auditory cortex, inferior colliculus and cochlear nucleus. However, expressions of them significantly decreased in the group B1 as compared to group B2 and group D (P＜0.05). Conclusion Auditory deprivation results in expressions of mRNAs and proteins encoded by bdnf and c-fos increas in early stage and decreasing in the later stage in auditory cortex, inferior colliculus and cochlear nucleus. Intracochlear electrical stimulation makes expression of them increase in rats with auditory deprivation. The dynamic variations of bdnf and c-fos and their proteins reflected the plasticity in neurons of the auditory pathway．