Neuroglobin基因体内转染对水杨酸钠给药后小鼠下丘核神经元听反应的影响

实验以48只成年健康昆明小鼠为实验对象,研究GeneJamer转染试剂介导的neuroglobin(NGB)基因体内转染对水杨酸钠给药后小鼠下丘核区听反应的影响。实验分4组,每组12只。A1组:对照组1(阴性对照,将GeneJamer转染试剂6μl和pEGFP-C12μg混合后注入下丘核脑区);A2组:对照组2[阳性对照,将GeneJamer转染试剂(6μl)和pEGFP-NGB(质粒载体pEGFP-C1与NGB基因全编码序列构建的重组子2μg)混合后注入下丘核脑区];B组:水杨酸钠给药组(450mg/kg·d-1)+pEGFP-C1;C组:水杨酸钠(450mg/kg.d-1)+pEGFP-NGB组。以直接注射法将GeneJamer转染试剂和重组质粒pEGFP-NGB混合后注入小鼠下丘核区。采用RT-PCR和Westernblot技术检测小鼠下丘核区NGBmRNA和蛋白的表达;采用细胞外记录技术,研究小鼠下丘核区神经元在水杨酸钠给药后转染重组质粒pEGFP-NGB对强度-发放率函数(刺激声强与实验鼠下丘核区神经元在接受声刺激所产生的电发放的关系曲线)、强度-潜伏期函数(刺激声强与实验鼠下丘核区神经元在接受声刺激至产生电发放潜伏期之间的关系曲线)和频率调谐曲线(实验鼠下丘核区神经元在各个频率纯音刺激下起反应的阈值绘制的曲线)的影响。实验观察到:(1)经GeneJamer转染试剂介导NGB基因可有效地转染小鼠下丘核区脑组织并得到表达。(2)水杨酸钠给药后神经元的强度-发放率函数曲线升高。对照组A1、A2各项指标进行比较均无统计学意义。对照组A1、A2和水杨酸钠+pEGFP-NGB组神经元的强度-发放率函数以非单调型(随刺激强度增加时,发放率表现为先降后升呈“V”形或“U”形)为主,分别占74.6%、72.2%和59.3%,水杨酸钠给药组以不规则型强度-发放率函数为主,占47%,与对照组A1、A2和水杨酸钠+pEGFP-NGB组比较,有显著性差异(P<0.01、P<0.01、P<0.05)。(3)水杨酸钠给药后神经元的强度-潜伏期函数曲线降低。对照组A1、A2各项指标进行比较均无统计学意义。水杨酸钠给药组以非单调型强度-潜伏期率函数为主,与对照组A1、A2和水杨酸钠+pEGFP-NGB组比较,有显著性差异(P<0.01、P<0.05)。(4)A1和A2对照组听反应神经元的调谐曲线,Q-10dB值均大于5.00,其调谐曲线为狭窄型。记录水杨酸钠给药组72个听神经元的调谐曲线,有53个神经元的Q-10dB值小于5.00,Q-10dB值最小为2.12,其调谐曲线为宽阔型;其余19个神经元的Q-10dB值大于5.00,属于狭窄型调谐曲线。水杨酸钠+pEGFP-NGB组67个听神经元的调谐曲线,有12个神经元的Q-10dB值小于5.00,Q-10dB值最小为2.87,其调谐曲线为宽阔型,其它的神经元的值大于5.00。它们的调谐曲线均属狭窄型。以上结果提示外源性NGB基因在水杨酸钠给药后小鼠下丘核区局部高表达,提示GeneJamer转染试剂介导NGB体内转基因治疗水杨酸钠引起的下丘核区的损伤的方法是可行的。实验小鼠转染NGB基因后可逆转因水杨酸钠给药引起的强度-发放率函数曲线升高以及强度-潜伏期函数曲线降低,并可逆转水杨酸钠引起的部分听神经元对声刺激强度的编码类型。

Effects of neuroglobin gene transfer in vivo on hearing response properties of neurons in the inferior colliculus in mice after administration of sodium salicylate

The effects of neuroglobin (NGB) gene transfer in vivo mediated by GeneJamer on the hearing response properties of theinferior colliculus (IC) neurons in mice after administration of sodium salicylate were studied. Forty-eight Kunming mice were dividedinto 4 groups (n=12 in each group): Group A1 (negative control); Group A2 (positive control); Group B, sodium salicylate (450 mg/kgevery day) + pEGFP-C1; Group C, sodium salicylate (450 mg/kg every day) + pEGFP-NGB. The GeneJamer and pEGFP-NGB weremixed and injected into IC neurons in mice. The expression of NGB mRNA and protein of IC neurons in mice was detected by using RT-PCR and Western blot methods. The intensity-rate functions, intensity-latency functions and frequency-turning curves in IC neuronswere recorded by extracellular electrophysiological recording techniques and the effects of pEGFP-NGB transfer following injection ofsodium salicylate on them were studied. It was found that: (1) The GeneJamer-mediated pEGFP-NGB could be effectively transferredinto the IC brain tissues in mice and NGB could be expressed intensively. (2) The intensity-rate functions of IC neurons were raisedafter administration of sodium salicylate. The non-monotonic styles of intensity-rate functions in groups A1, A2 and C were accountedfor 74.6 %, 72.2 %, 59.3 %, respectively, and the function in group B for 47%. There were significant differences between group B andgroups A1, A2 or C (P<0.01, P<0.01, P<0.05). (3) The intensity-latency functions in IC neurons were reduced after administration ofsodium salicylate. The non-monotonic styles of intensity-latency functions in groups A1, A2 and C were accounted for 3.2 %, 5.1 %and 21 %, respectively, and that in group B for 45.5 %. There were significant differences between group B and groups A1, A2 or C (P<0.01, P<0.01, P<0.05, respectively). (4) The frequency-turning curves in groups A1 and A2 were sharpened. In 72 acoustic neuronsrecorded in the group B, the frequency-turning curves from 53 neurons were broadened while those of the rest were sharpened. In groupC the frequency-turning curves recorded from 12 of 67 acoustic neurons were broadened while those of the remaining were sharpened.These results suggest that in vivo transfer of NGB gene is highly expressed in IC neurons in mice. In vivo transfer of NGB gene reversesthe change of intensity-rate functions, intensity-latency functions and the code styles after administration of sodium salicylate in ICneurons in mice.