听觉剥夺及耳蜗内电刺激幼鼠听皮层和下丘核CREB 和 NMDAR1蛋白表达变化

目的：观察耳聋幼鼠及其耳聋后单耳植入电极电刺激后幼鼠听皮层和下丘核环磷酸腺苷反应元件结合蛋白（cyclic AMP response element － binding protein ，CREB）和N －甲基－D－天冬氨酸受体－1（N －methyl－D－aspartic acid receptor one ，NMDAR1）表达水平的变化。方法将66只12天龄SD幼鼠随机分为2大组，分别为耳聋造模后4周组（33只）及耳聋造模后6周组（33只）。将耳聋造模后4周组再分为对照1组、耳聋造模后4周组（4周组）及耳聋造模后3周耳蜗内电刺激组1（刺激时间为1周，简称“电刺激1组”），每组11只大鼠；将耳聋造模后6周组再分为对照2组、耳聋造模后6周组（6周组）及耳聋造模后5周耳蜗内电刺激组2（刺激时间为1周，简称“电刺激2组”），每组11只大鼠；对照1、2组均正常饲养。除对照1、2组外，在其余4组幼鼠颈背部、两侧下腹部皮下注射庆大霉素（总量为350 mg／kg ），半小时后于相同部位注射呋塞米（总量为200 mg／kg ），两周后行ABR检测，于耳聋造模成功后第3、5周分别对电刺激1、2组的幼鼠植入电极，在耳蜗内进行电刺激，每天3小时，持续7天。于耳聋造模后4、6周分别处死4、6周组大鼠取听皮层和下丘组织，通过免疫组织化学方法，观察CREB和NMDAR1表达水平的变化。结果耳聋造模成功后幼鼠ABR阈值均大于93 dB SPL ，4周组听皮层、下丘CREB和NMDAR1的表达较对照1组增加，电刺激1组CREB和NMDAR1的表达较4周组增加。6周组听皮层和下丘CREB和NMDAR1的表达较对照2组下降，电刺激2组CREB和NMDAR1的表达较6周组增加。结论听觉剥夺可导致幼鼠听皮层和下丘CREB和NMDAR1早期表达增加而晚期表达下降。耳蜗植入电极电刺激可导致幼鼠听皮层和下丘CREB和NMDAR1的表达增加，反映这两个部位神经元的可塑性变化。

Variation of CREB and NMDAR1 Proteins Induced by Auditory Deprivation and Intracochlear Electrical Stimulation in Infant Rats

Objective To observe the expression of cAMP -response element binding protein (CREB) and N-methyl-D-aspartic acid receptor (NMDA ) after intracochlear electrical stimulation in the auditory cortex and inferior colliculus in infant rats with auditory deprivation .Methods Sixty six SD infant rats were randomly divided into 6 groups (11 rats each group):4 weeks ,and 6 weeks after injection of ototoxic drug ,the control group ,and 3 weeks and 5 weeks after injection of ototoxic drug with intra -cochlear electrical stimulation for one week .Gentami-cin sulphate (350 mg/kg body weight) and frusemide (200 mg/kg body weight) were injected subcutaneously in the skin folds on the lateral abdominal side and the dorsal neck area ,respectively .The expression of CREB and NMDAR1protein were detected by immunohistological staining .Results The results of immunohisto -chemistry revealed that protein expression of CREB and NMDAR1 in 4 week group of injection increased as compared to the control group ,while decreasing as compared to intracochlear electrical stimulation group ,significantly .However ,protein expression of CREB and NMDAR1 in 6 week group of injection decreased as compared to the control group and in-tracochlear electrical stimulation group ,significantly .Conclusion Auditory deprivation could result in the expres-sion of protein of CREB and NMDAR1 in auditory cortex and inferior colliculus increasing in an early stage and then de-creasing in infant rats .Intracochlear electrical stimulation could result in the expression of proteins of CREB and NMDAR 1 in auditory cortex and inferior colliculus increasing in infant rats .The dynamic variation of CREB and NMDAR1 expression in rat auditory cortex and inferior colliculus reflects synaptic plasticity in neurons of auditory pathway .