Physiology of Cholinergic Basal Forebrain Neurons

描述(由申请人提供)：在人类和动物模型中，神经元钙(Ca~(2+))稳态的破坏与衰老和认知衰退有关。然而，认知障碍在老龄化人口中是可变的，某些神经细胞类型比其他类型更容易受到年龄相关变化的影响。在人类中，基底前脑中的胆碱能神经元优先受到年龄相关功能障碍的影响，包括阿尔茨海默病。在大鼠中，基底前脑的胆碱能功能障碍与认知功能障碍有关，但介导认知功能障碍的细胞和分子机制在很大程度上尚不清楚。我们的实验室描述了大鼠内侧隔核和斜角带核(MS/NDB)神经元的基因表达和功能生理学与年龄相关的差异。为了了解与年龄相关的认知障碍的细胞和分子机制，我们需要在衰老模型中定义与认知功能下降相关的神经元生理学/分子生物学的细胞类型特定模式。我们假设，与年龄相关的钙稳态功能的变化会对特定亚型的胆碱能神经元产生不同的影响，这些变化的启动会导致认知能力下降，这一下降可以通过适当的药物来逆转或预防。为了研究这一点，我们将使用实时荧光检测PCR检测不同年龄(年轻，1-4个月；中年，12-16个月；老年，24-26个月)急性分离的344只大鼠MS/NDB神经元的mRNA表达，以定量表达并鉴定细胞类型。分子描述将与电压门控钙通道、钙稳态和线粒体的功能分析相结合，使用膜片钳电生理学、钙敏感比率显微荧光法、激光扫描共聚焦显微镜和电子显微镜。在与基底前脑胆碱能系统(Morris水迷宫)相关的空间记忆测试中，每只大鼠的行为特征将被描述为认知受损或非受损，从而使我们能够将细胞结果与认知状态联系起来。我们将为每种动物定义至少三种功能和分子特性。最后，我们将用多奈哌齐(胆碱酯酶抑制剂)或尼莫地平(钙通道阻滞剂)治疗大鼠，以逆转与年龄相关的行为障碍和生理变化。

DESCRIPTION (provided by applicant): Disruption of neuronal calcium (Ca2+) homeostasis is associated with aging and cognitive decline in humans and animal models. However, cognitive impairment is variable in the aging population and certain neuronal cell-types are more susceptible to age-related changes than others. In humans, cholinergic neurons in the basal forebrain are preferentially affected by age-related dysfunction, including Alzheimer's disease. In rats, cholinergic dysfunction in the basal forebrain has been associated with cognitive impairment, but the cellular and molecular mechanisms that mediate cognitive dysfunction are largely unknown. Our lab has described age-related differences in gene expression and functional physiology of neurons from the rat medial septum and nucleus of the diagonal band (MS/nDB). To understand the cellular and molecular mechanisms responsible for age-related cognitive impairment, we need to define cell-type specific patterns of neuronal physiology/molecular biology relevant to cognitive decline in an aging model. We hypothesize that age-related changes in Ca2+ homeostatic function differentially affect specific subtypes of cholinergic neurons and that the initiation of these changes precipitates a cognitive decline that can be reversed or prevented by appropriate pharmacology. To investigate this, we will measure mRNA expression in acutely dissociated MS/nDB neurons from Fischer 344 rats of different ages (young, 1-4 months; middle, 12-16 months; aged, 24-26 months) using real-time fluorescent detection PCR to quantitate expression and identify cell-types. Molecular descriptions will be combined with functional assays of voltage-gated Ca2+ channels, Ca2+ homeostasis and mitochondria using patch-clamp electrophysiology, Ca2+ sensitive ratiometric microfluorimetry, laser scanning confocal microscopy and electron microscopy. Each rat will be behaviorally characterized as cognitively impaired or nonimpaired in a spatial memory test relevant to the basal forebrain cholinergic system (Morris water maze), allowing us to associate cellular results with cognitive status. We will define at least three functional and molecular properties from each animal. Finally, we will treat rats with donepezil (cholinesterase inhibitor) or nimodipine (Ca2+ channel blocker) to reverse age-related behavioral impairments and physiological changes.