METABOTROPIC GLUTAMATE RECEPTORS AND EXCITOTOXICITY

描述（由申请人提供）：谷氨酸是大脑中最普遍的神经递质。代谢型谷氨酸受体（mGluRs）是调节脑中兴奋性突触处的神经传递的G蛋白偶联受体家族。mGluR亚型的多样性和异质性分布可能为开发选择性靶向特定CNS系统并改善不同神经系统疾病症状的药物提供了机会。然而，mGluRs在兴奋性毒性中的作用仍然存在争议。外侧隔核是边缘系统的主要中继核团。在外侧隔神经元中，mGluR激动剂引起癫痫样爆发性放电，并大大提高细胞内游离钙。初步数据表明，这种钙增加导致严重的兴奋性毒性，这是独立的离子型谷氨酸受体。本研究的目的是确定介导癫痫爆发放电和兴奋性毒性的大鼠外侧隔中的mGluRs的分子性质。在Aiml中，将测试新一代基团选择性激动剂和拮抗剂。细胞内记录将用于研究这些药物对外侧隔神经元放电模式的影响。通过碘化丙啶（PI）加载和荧光玉染色评估切片中的兴奋性毒性。这些实验将确定癫痫样爆发放电和兴奋性毒性是否由I组mGluRs单独介导。在目的2中，将产生靶向大鼠mGluRl或mGluRS的siRNA试剂，并用于在大鼠隔的器官型培养物中功能性沉默mGluRl或mGluRS的表达。然后将评估选择性降低mGluRl或mGluRS表达对mGluR介导的兴奋性毒性的影响。通过结合药理学和RNA干扰的方法，介导的癫痫爆发放电和兴奋性毒性在外侧隔神经元的mGluRs的分子性质将被阐明。这些发现将为开发可用于治疗帕金森病、癫痫发作、精神病和与中风相关的兴奋性毒性的药物提供关键信息。

DESCRIPTION (provided by applicant): Glutamate is the most prevalent neurotransmitter in the brain. Metabotropic glutamate receptors (mGluRs) are a family of G-protein coupled receptors that regulate neurotransmission at excitatory synapses in the brain. The diversity and heterogeneous distribution of mGluR subtypes may provide an opportunity for developing drugs to selectively target a specific CNS system and ameliorate symptoms of distinct neurological disorders. However, the role of mGluRs in excitotoxicity remains controversial. The lateral septal nucleus is a major relay nucleus in the limbic system. In lateral septal neurons, mGluR agonists elicit epileptiform burst firing and greatly elevate intracellular free calcium. Preliminary data suggest that this calcium increase results in severe excitotoxicity that is independent of ionotropic glutamate receptors. The goal of this study is to determine the molecular nature of the mGluRs in the lateral septum of rats that mediate the epileptic burst firing and excitotoxicity. In Aiml, a new generation of group selective agonists and antagonists will be tested. Intracellular recordings will be used to study the effects of these drugs on the firing pattern of lateral septal neurons. Excitotoxicity in the slices will be assessed by propidium iodide (PI) loading and fluoro-jade staining. These experiments will determine whether epileptiform burst firing and excitotoxicity are mediated by group I mGluRs alone. In Aim 2, siRNA reagents that target rat mGluRl or mGluRS will be generated and used to functionally silence the expression of mGluRl or mGluRS in organotypic cultures of the rat septum. The effect of selectively reducing mGluRl or mGluRS expression on mGluR-mediated excitotoxicity will then be assessed. By combining pharmacological and RNA-interference approaches, the molecular nature of the mGluRs that mediate the epileptic burst firing and excitotoxicity in lateral septal neurons will be elucidated. The findings will provide critical information for developing drugs that can be used to treat Parkinson's diseases, seizures, psychosis and excitotoxicity associated with stroke.