PHYSIOLOGY OF CHOLINERGIC BASAL FOREBRAIN NEURONS

据报道，许多依赖钙(Ca~(2+))的系统正在衰退 随着年龄的增长。钙离子动态平衡受损最近已经成为一种 有记录的衰老表现，此外，可能有助于 一些神经退行性疾病，如老年痴呆症。精准的 参与这种钙稳态变化的细胞机制尚未见报道 已经确定了。这项提案的目的将是将 基底前脑已识别神经元钙离子调节的变化 在成熟和老化过程中。这些神经元之所以被选中，是因为它们发挥作用 在记忆和认知中起着关键作用，并与 几种神经系统疾病的临床症状。我们将测试 假设存在与年龄相关的和特定于细胞的 电压门控钙通道(VGCC)在衰老过程中发挥作用。这一假设 将通过研究钙离子调节的三个关键方面进行测试 包括：a)通过VGCC通过全细胞和单个细胞的钙离子进入 通道膜片钳记录，b)细胞内游离钙浓度 显微荧光技术，以及c)神经递质对VGCC的调节 已知的控制电压依赖性钙离子运动的系统。所有这些都是 参数可以通过直接作用于离子门控来调节VGCC， 细胞内游离钙离子的变化，或涉及信号的间接变化 转导和第二信使调节。实验将是 使用Fischer 344大鼠(1个月、12个月和20个月龄 组)在两种体外制剂中；要么是急性分离的细胞，要么是 在一个薄薄的脑片准备中。薄片制剂也将 使我们能够识别胆碱能神经元和非胆碱能神经元 双重标记技术。 许多与年龄相关的缺陷已被证明是部分的，如果不是的话 完全逆转，通过恢复适当的细胞钙水平或 通量，表明对神经元钙离子调节的控制是合法的 治疗潜力。这些实验的结果不仅将 提供有关与年龄相关的控制的新的量化信息 神经元内钙稳态，但更重要的是，为 未来的治疗方法。

A number of calcium (Ca2+)-dependent systems have been reported to decline with aging. Impaired Ca2+ homeostasis has recently emerged as a well documented manifestation of aging and, in addition, may contribute to several neurodegenerative disorders such as senile dementia. The precise cellular mechanisms involved in this change in Ca2+ homeostasis have not been determined. The purpose of this proposal will be to characterize changes in Ca2+ ion regulation in identified neurons of the basal forebrain during maturation and aging. These neurons were chosen because they play a pivotal role in memory and cognition as well as having relevance to the clinical symptoms of several neurological disorders. We will test the hypothesis that there is an age-related and cell-specific decline in voltage-gated Ca2+ channel (VGCC) function during aging. This hypothesis will be tested by investigating three key aspects of Ca2+ regulation including; a) Ca2+ entry through VGCC using both whole-cell and single- channel patch-clamp recordings, b) free cytosolic Ca2+ concentrations using microfluorometric techniques, and c) regulation of VGCC by neurotransmitter systems known to control voltage-dependent Ca2+ movement. All of these parameters could regulate VGCCs through direct actions on ion gating, alterations in free cytosolic Ca2+, or indirect changes involving signal transduction and second messenger modulation. Experiments will be performed using Fischer 344 rats (1 month, 12 month and 20 month age groups) in two in vitro preparations; either acutely dissociated cells or in a thin brain slice preparation. The thin slice preparation will also enable us to identify cholinergic versus noncholinergic neurons using double-labelling techniques. Many age-related deficits have been shown to be partially, if not completely, reversed by restoration of appropriate cellular Ca2+ levels or fluxes, suggesting control over neuronal Ca2+ regulation has legitimate therapeutic potential. Results from these experiments will not only provide new quantitative information concerning age-related control of neuronal Ca2+ homeostasis but, more importantly, provide direction for future therapeutic treatments.