TNF-α Signaling in Noise Trauma-Induced PV Neuron Loss and Dysfunction

项目摘要/摘要 噪声损伤可导致听皮层小白蛋白阳性抑制性中间神经元的丢失，这是 在啮齿动物模型中与听觉处理缺陷和耳鸣有关。噪音背后的机制- 诱导的PV神经元丢失尚不清楚。我们建议检验这样一种假设，即差异激活 皮层PV神经元中的TNFR1和TNFR2决定了噪声损伤后PV神经元的命运， TNFR1偏向神经元丢失和功能障碍，以及TNFR2偏向神经元丢失和功能障碍。 具体目的1.确定TNFR1或TNFR2基因敲除对噪声诱导的PV神经元丢失的影响。 将向PV-Cre-td番茄小鼠注射三种病毒载体中的一种(带有TNFR1 shRNA、TNFR2 shRNA或 加扰序列作为对照)，暴露或假暴露于噪声创伤。光伏 CRE记者tdTomato将在听觉皮质切片上显示神经元。转基因神经元将 与病毒式记者GFP一起被可视化。我们的假设预测，噪声引起的PV神经元损失将是 对于转基因的PV神经元，TNFR1基因敲除可使其表达降低，但可被TNFR2基因敲除所增强。信元丢失 不应改变未转染的光伏神经元的群体，以及转染了 加扰序列。 特定目的2.检测TNFR1或TNFR2基因敲除对噪声诱导的PV功能障碍的影响 神经元突触。我们的飞行员数据表明，噪声损伤导致发射机释放概率降低 在PV神经元的输出突触上，加速了神经递质的枯竭。我们假设这是 突触功能障碍依赖于存活的PV神经元中TNFR1的激活和TNFR1的下调 将防止突触缺陷。此外，TNFR2基因敲除可能会加重PV神经元功能障碍。 PV-Cre-ChR2-td番茄小鼠将在听觉皮质注射三种病毒载体之一，并将 暴露于或假暴露于噪音创伤。我们将记录光学激活的抑制性突触电流 急性听皮层脑片内2/3层锥体神经元。突触输入输出曲线，成对脉冲 我们将研究调制和耗尽。然后，将切片固定并成像以对PV神经元进行量化 存活的PV神经元中的丢失和病毒转染率，这将与PV神经元突触相关 功能障碍。我们假设噪声暴露扰乱了皮质PV神经元的功能，而PV神经元 功能障碍是缺口检测缺陷的原因之一。我们建议使用小鼠模型来检验这一中心假设 在接下来的具体目标中。

PROJECT SUMMARY/ABSTRACT Noise trauma can lead to loss of parvalbumin-positive inhibitory interneurons in the auditory cortex, which is associated with audiotory processing deficit and tinnitus in rodent models. The mechanisms underlying noise- induced PV neuron loss are unknown. We propose to examine the hypothesis that differential activation of TNFR1 and TNFR2 in cortical PV neurons determines the fate of the PV neurons following noise trauma, with TNFR1 biasing for, and TNFR2 biasing against, neuronal loss and dysfunction. Specific Aim 1. Determine the effects of TNFR1 or TNFR2 knockdown on noise-induced PV neuron loss. PV-Cre-tdTomato mice will be injected with one of three viral vectors (with TNFR1 shRNA, TNFR2 shRNA or scrambled sequences as a control) in the auditory cortex, and exposed or sham-exposed to noise trauma. PV neurons will be visualized by the Cre reporter tdTomato in auditory cortical sections. Transfected neurons will be visualized with the viral reporter GFP. Our hypothesis predicts that noise-induced PV neuron loss will be reduced by TNFR1 knockdown, but enhanced by TNFR2 knockdown for the transfected PV neurons. Cell loss should not be altered for the populations of un-transfected PV neurons, and PV neurons transfected with the scrambled sequences. Specific Aim 2. Examine the effects of TNFR1 or TNFR2 knockdown on noise-induced dysfunction of PV neuron synapses. Our pilot data indicate that noise trauma leads to a reduced transmitter release probability at the output synapses of the PV neurons, and accelerated neurotransmitter depletion. We hypothesize that this synaptic dysfunction depends on the activation of TNFR1 in the surviving PV neurons, and knockdown of TNFR1 will prevent the synaptic deficits. In addition, knockdown of TNFR2 should exacerbate PV neuron dysfunction. PV-Cre-ChR2-tdTomato mice will be injected with one of the three viral vectors in the auditory cortex, and be exposed or sham-exposed to noise trauma. We will record optically activated inhibitory synaptic current in Layer2/3 pyramidal neurons in acute auditory cortical slices. Synaptic input-output curve, paired-pulse modulation and depletion will be examined. Afterward, the slices will be fixed and imaged to quantify PV neuron loss and viral transfection rate in the surviving PV neurons, which will then be correlated with PV neuron synaptic dysfunction.We hypothesize that noise exposure disrupts cortical PV neuron function, and PV neuron dysfunction is a cause of gap detection deficit. We propose to use a mouse model to test this central hypothesis in the follwing specific aims.