Dopamine signal transduction in striatal neurons in Parkinson’s disease

项目摘要 帕金森氏病(PD)的特征是运动异常，主要是由于中脑多巴胺的丧失引起的 (DA)细胞，其主要功能是调节纹状体神经元的活动。用L-多巴取代DA 能显著改善运动障碍，但随着时间的推移，L-多巴的整体疗效会下降。 疾病进展和慢性多巴胺能治疗共同诱导纹状体适应不良可塑性 投射神经元(SPN)，导致对DA输入的反应改变。SPN中的DA信号被转导 通过DA受体激活后的各种分子级联反应。在这些级联中的第一步是监管 环一磷酸腺苷(CAMP)和环鸟苷一磷酸(CGMP)的合成。这些 环核苷酸激活其依赖的蛋白激酶PKA和PKG，它们是多发性硬化的关键介质。 细胞功能。因此，多巴胺对SPN的调节主要通过cAMP-PKA和cGMP-PKG途径进行。 然而，这些酶通路在神经元经历了显著的DA反应后所起的作用 不适应的可塑性变化是未知的。此外，可能会有不同的功能结果 这些酶途径在不同的SPN亚群中被激活。基于我们的药理研究 针对暗示cGMP-PKG途径关键作用的核苷酸水平，我们建议探索其影响 在SPN亚群中选择性地操纵PKG活性。孤束核中多巴胺信号转导的研究 亚群的目的是确定关键的细胞机制，可以针对这些机制来提高 多巴胺能疗法。 这个项目有两个具体的目标，包括对啮齿动物模型的行为和生理分析 帕金森病包括慢性期。在第一个目标中，我们将在选择性神经元中操纵PKG的活性。 子类型。为此，我们将使用表达Cre系统的转基因大鼠，然后将病毒载体注射到 在直接或间接SPN中高表达PKG。将使用一系列行为测试来评估 PKG通路在帕金森病模型运动障碍中的作用及其被多巴胺能刺激逆转。 在第二个目标中，我们将分析PKG过度表达时神经元的活动，这将使 我们需要建立行为结果的生理关联。对于这些录音，我们也将使用转基因 并应用光遗传学来识别直接和间接SPN。我们的方法包括使用新的动物 帕金森病中DA信号转导的关键病理生理机制的模型和技术。这个 这些探索性研究的主要目的是：(1)揭示cGMP-PKG通路的特殊作用 根据细胞亚型，以及(Ii)为继续这项重要研究生成基础数据 程序。该计划的长期目标是开发新的策略来缓解运动障碍 帕金森病病程较长的患者。

Project Summary Parkinson’s disease (PD) is characterized by motor abnormalities primarily caused by loss of midbrain dopamine (DA) cells, whose principal function is to modulate the striatal neuron activity. DA replacement with L-Dopa produces significant improvement of motor deficits, but over time the overall efficacy of L-Dopa declines. Together disease progression and chronic dopaminergic treatment induces maladaptive plasticity in striatal projection neurons (SPNs), which results in altered responses to DA inputs. DA signaling in SPNs is transduced by various molecular cascades following DA receptor activation. The first step in these cascades is the regulation of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) syntheses. These cyclic nucleotides activate their dependent protein kinases PKA and PKG, which are key mediators in multiple cell functions. Thus, DA modulation of SPNs is largely transduced by the cAMP-PKA and cGMP-PKG pathways. However, the roles of these enzyme pathways for DA responses after neurons have undergone significant maladaptive plasticity changes are not known. Furthermore, there may be different functional outcomes from activation of these enzyme pathways in distinct SPN subpopulations. Based on our pharmacological studies targeting nucleotide levels that suggest a key role of the cGMP-PKG pathway, we propose to explore the impact of manipulating PKG activity selectively in SPN subpopulations. This study of DA signal transduction in SPN subpopulations is aimed at identifying key cellular mechanisms that can be targeted to improve the efficacy of dopaminergic therapies. This project has two specific aims consisting of behavioral and physiological analyses in rodent models of PD including chronic stages. In the first aim, we will manipulate the activity of PKG in selective neuronal subtypes. For this purpose, we will use transgenic rats expressing a Cre system, and then inject viral vectors to overexpress PKG in direct or indirect SPNs. A battery of behavioral tests will be used to assess the role of the PKG pathway in the motor impairment of parkinsonian models as well as its reversal by dopaminergic stimulation. In the second aim, we will analyze the neuronal activity in response to overexpression of PKG, which will allow us to establish physiological correlates of behavioral results. For these recordings, we will also use transgenic rats and apply optogenetics to identify direct and indirect SPNs. Our approach includes the use of novel animal models and technologies to address key pathophysiologic mechanisms of DA signal transduction in PD. The main objectives of these exploratory studies are (I) to reveal particular roles of the cGMP-PKG pathway depending on the cellular subtype, and (II) to generate foundation data for continuation of this important research program. The long-term goal of the program is developing new strategies to alleviate the motor impairment of patients during the long course of PD.