Oxidative damage to receptor: G-protein coupling in the aged hippocampus

描述（由申请人提供）：衰老与许多认知领域的衰退有关，尤其是记忆。到2040年，65岁以上的人将占美国人口的20%以上，因此迫切需要阐明衰老损害记忆的机制，并确定改进的治疗干预途径。重要的是，对人类的神经心理学评估表明，并非所有老年人都会被临床诊断为记忆障碍，这表明时间衰老和认知衰老并不是同义词。与阿尔茨海默病不同，与年龄相关的记忆变化与大范围的神经元丧失无关；相反，海马体中突触数量的选择性减少以及突触后受体的反应性降低。这些在老年人身上出现的行为和神经元后遗症可以成功地在老年大鼠身上进行空间位置记忆测试。该项目将利用啮齿动物的衰老模型，整合时间和认知衰老的各个方面，研究突触前和突触后基质的相关变化。对谷氨酸能、胆碱能和gaba能海马回路和受体的平行分析将确定变化是特定于特定的神经递质系统还是老年大脑中更普遍的变化。海马神经支配的变化将通过免疫组织化学染色技术可视化，并使用无偏体视学方法量化。M1毒蕈碱-和mGluR5代谢性谷氨酸受体介导的gtp结合（受体偶联的功能测量）将使用特定于其同源g蛋白1亚基Gq/11的闪烁接近计数技术进行选择性测量。这些变化将通过GABAB受体介导的结合来对比，这种结合不会随着年龄的增长而恶化，而是通过Gi/Go级联发出信号。在没有明显的受体和g蛋白损失的情况下，假设与衰老海马中氧化应激相关的分子过程可能干扰正常的信号转导。为了验证这一假设，受体和g蛋白将通过免疫沉淀和质谱分析来确定这些特定的蛋白质是否被氧化损伤。总的来说，这个项目将评估与正常记忆功能密切相关的三种神经递质系统的年龄相关变化，并确定这些回路和突触在衰老过程中发生变化的机制。从这些实验中获得的数据不仅将极大地增强对大脑衰老和认知的理解，而且还将阐明下一代药物治疗中潜在治疗调节感兴趣的特定神经基质的变化。此外，为解决这些重点研究工作而提出的实验方法的多样性将为申请人提供优秀的博士前培训经验，以支持他所陈述的职业目标和目标。

DESCRIPTION (provided by applicant): Aging is associated with declines in a number of cognitive domains, particularly memory. As people over the age of 65 will comprise more than 20% of the US population by the year 2040, there is a pressing need to elucidate the mechanisms by which aging impairs memory and to identify improved routes of therapeutic intervention. Importantly, neuropsychological assessments of humans demonstrate that not all aged individuals will be clinically diagnosed with memory impairment, demonstrating that chronological and cognitive aging are not synonymous processes. Unlike Alzheimer's disease, age-related changes in memory are not associated with wide-spread neuronal loss; rather there is a selective decrease in the numbers of synapses within the hippocampus and decreased responsivity of post-synaptic receptors. These behavioral and neuronal sequelae apparent in aged humans can be successfully modeled in aged rats tested for memory of spatial locations. This project will make use of a rodent model of aging integrating aspects of chronological and cognitive aging to investigate associated changes in presynaptic and postsynaptic substrates. Parallel analysis of glutamatergic, cholinergic and GABAergic hippocampal circuits and receptors will determine if changes are specific to a particular neurotransmitter system or more general changes in the aged brain. Changes to innervation of the hippocampus will be visualized by immunohistochemical staining techniques and quantified using unbiased stereological approaches. M1 muscarinic- and mGluR5 metabotropic glutmate receptor-mediated GTP-binding, a functional measure of receptor coupling, will be selectively measured using a scintillation proximity counting technique specific to their cognate G-protein 1-subunit, Gq/11. These changes will be contrasted by measures of GABAB receptor-mediated binding which do not deteriorate with age, but signal via a Gi/Go cascade. In the absence of overt loss of receptor and G-proteins, it has been hypothesized that molecular processes associated with oxidative stress in the aged hippocampus may interfere with normal signal transduction. To test this hypothesis, receptors and G-proteins will be analyzed by immunoprecipitation and mass spectrometry to determine if these specific proteins are oxidatively damaged. Collectively, this project will evaluate age-related changes in three neurotransmitter systems closely tied to normal memory function and determine the mechanisms by which these circuits and synapses are changed in aging. The data derived from these experiments will not only greatly enhance understanding of brain aging and cognition, but elucidate changes to specific neural substrates that are of interest for potential therapeutic modulation by the next generation of pharmaceutical treatments. Furthermore, the diversity of experimental approaches proposed to address these focused research efforts will provide for an excellent pre-doctoral training experience to the applicant in support of his stated career goals and objectives. PUBLIC HEALTH RELEVANCE: As people over the age of 65 will comprise more than 20% of the U.S. population by 2040, appreciating the mechanisms by which memory declines in the elderly is matter of pressing scientific and clinical concern. This research project will measure presynaptic and postsynaptic aspects of neural signaling to determine specific changes to metabotropic receptors and G-proteins in the aged hippocampus associated with memory deficits. The findings of this project will enhance our understanding of the aged brain and provide new insights for therapeutic treatment potential.