AMPA RECEPTOR EXPRESSION AND SELECTIVE NEURONAL DEATH

某些神经元的选择性破坏标志着许多神经系统疾病，包括小脑变性和运动神经元疾病，如ALS。 大量证据表明，这些疾病的变性可能是兴奋性毒性造成的，其中谷氨酸受体的过度激活导致神经元损伤。 此外，最好的模型表明，在这些疾病中，小脑浦肯野细胞和脊髓运动神经元的两种神经元类型的破坏，是由AMPA亚型的谷氨酸受体介导的。该项目将通过在分子水平上将AMPA受体表达的特定模式与毒性相关的功能性受体特性联系起来，研究这些神经元的选择性脆弱性机制。 特别是，AMPA受体的表达，是相对抵抗脱敏，或具有较高的渗透性的Ca2+的受体可能会使这些细胞选择性地容易受到谷氨酸毒性。 本研究将从以下几个方面对AMPA受体的功能特性进行研究：1.利用单细胞PCR扩增技术结合膜片钳技术研究浦肯野神经元AMPA受体亚基mRNA的表达模式是否决定了浦肯野神经元AMPA受体的功能特性。 2.探讨浦肯野细胞AMPA受体的脱敏和Ca2+通透性与其在与特异性毒性相关的电生理研究中的选择性易损性的关系。 3.明确AMPA受体的功能特性及其在运动神经元中的分子表达模式。 再次，脱敏和Ca2+通透性的测定亚基表达将使用单细胞PCR和膜片钳研究。 4.在器官型脊髓切片培养物中检测脊髓运动神经元中负责选择性易损性的受体亚型，确定负责选择性易损性的AMPA受体的特性。了解AMPA受体的特性如何导致浦肯野细胞和脊髓运动神经元的选择性损伤，可能是了解其变性机制和识别小脑变性和ALS中神经保护的最佳分子靶点的关键。

Selective destruction of certain neurons marks many of the neurological diseases, including the cerebellar degenerations and motor neuron diseases such as ALS. Considerable evidence suggests that the degeneration in these diseases may result from excitotoxicity, in which excessive activation of glutamate receptors leads to neuronal damage. Furthermore, the best models suggest that the damage to the two neuronal types destroyed in these diseases, cerebellar Purkinje cells and spinal motor neurons, is mediated by the AMPA subtype of glutamate receptors. This project will study the mechanism of the selective vulnerability of these neurons by relating their particular patterns of AMPA receptor expression at the molecular level to functional receptor properties relevant to toxicity. In particular, expression of AMPA receptors that are relatively resistant to desensitization, or of receptors that have higher permeability to Ca2+ may render these cells selectively vulnerable to glutamate toxicity. These issues will be investigated in the following specific aims: 1 To assess whether the functional properties of AMPA receptors in Purkinje neurons are determined by the AMPA subunit mRNA expression pattern using single cell PCR amplification in conjunction with patch-clamp electrophysiological studies. 2. To explore the relationship of the desensitization and Ca2+ permeability of AMPA receptors expressed in Purkinje cells to their selective vulnerability in electrophysiological studies correlated with specific toxicity in culture. 3. To define the functional properties of AMPA receptors and their molecular expression pattern of motor neurons. Again, the determination of desensitization and Ca2+ permeability by subunit expression will be studied using single cell PCR and patch-clamp studies. 4. To examine the receptor subtypes responsible for selective vulnerability in spinal motor neurons in organotypic spinal cord slice cultures, identifying the properties of AMPA receptors responsible for selective vulnerability. Understanding how the properties of AMPA receptors can lead to selective damage to Purkinje cells and spinal motor neurons may hold the key to understanding the mechanisms of their degeneration and to recognition of the best molecular targets for neuroprotection in cerebellar degenerations and ALS.