Phosphodiesterase inhibitors for Parkinson’s Disease therapy

摘要 帕金森病(PD)的主要特征是运动障碍和黑质纹状体多巴胺(DA)细胞 损失。L-多巴置换DA最初改善了患者的活动能力，但长期的治疗与运动有关 并发症包括L-多巴诱发的运动障碍(LIDs)。DA更换的主要影响是 纹状体投射神经元(SPN)活动的调节。然而，非生理性的慢性多巴胺能 刺激与适应不良的可塑性和改变SPN对DA输入的反应有关。DA信令是 DA受体激活及其对cAMP和cGMP合成的影响。这些核苷酸是 也受其分解代谢酶--磷酸二酯酶(PDE)的调节。因此，PDE可能会影响 慢性L-多巴治疗后SPN的DA信号。这项提议将检验选择性的假设 磷酸二酯酶抑制剂(PDE-IS)可改善慢性治疗后对L-多巴的运动反应。我们的 假说是基于PDE家族在大脑中的不同分布及其特定的底物亲和力。 这些特性表明，选择性PDE-IS靶向于SPN中特定的cAMP和cGMP机制 亚群和诱导特定的运动效应。在这个项目中，我们计划分析运动效果和 帕金森病动物模型中PDE-IS的生理纹状体相关性。 我们的研究计划包括两个具体目标，每个目标都有两个子目标，以确定行为和SPN 对选择性PDE-IS结合灵长类和啮齿动物帕金森病模型的反应。我们将分析电机和SPN PDE-IS(PDE10A、PDE7B和PDE9抑制剂)对L-多巴的反应。这些PDE是 在纹状体中高表达，并具有不同的底物亲和力(cAMP和/或cGMP)。我们将使用 高级PD的灵长类MPTP模型用于结果的可译性。偏侧帕金森病大鼠也将被用来 在SPN响应分析中优化我们的细胞分辨率。我们将评估帕金森病患者的运动障碍和 LID具有既定的方法、适当的统计能力和严格的实验设计。我们包括 电生理学(单细胞记录)、脑内注射药物和钙指示剂(纤维 光度法)，用于体内SPN活性分析。我们还将使用转基因模型来评估反应。 TO PDE--专门用于直接和间接SPN。这些实验的结果将有助于揭示DA信号 在SPN亚群中，PDE对其的调节，以及L-多巴的相关运动效应。我们的长期目标是 将我们的发现转化为一种新的治疗方法来减少SPN中异常的DA信号，并改善 L-多巴治疗帕金森病患者的运动反应。为此，我们预计将通过建议的 PD模型中PDE函数的新研究。

SUMMARY Parkinson's Disease (PD) is primarily characterized by motor impairment and nigrostriatal dopamine (DA) cell loss. DA replacement with L-Dopa improve mobility initially, but long-term therapy is associated with motor complications including L-Dopa-induced dyskinesias (LIDs). The major effect of DA replacement is the modulation of activity of striatal projection neurons (SPNs). However, non-physiologic, chronic dopaminergic stimulation is associated with maladaptive plasticity and altered SPN responses to DA inputs. DA signaling is mediated by DA receptor activation and its effects on the synthesis of cAMP and cGMP. These nucleotides are also regulated by their catabolic enzymes, the phosphodiesterases (PDEs). Therefore, PDEs may impact the DA signals in SPNs after chronic L-Dopa treatment. This proposal will test the hypothesis that selective phosphodiesterase inhibitors (PDE-Is) may improve motor responses to L-Dopa following chronic treatment. Our hypothesis is based on differential distribution of PDE families in the brain and their specific substrate affinity. These properties suggest that selective PDE-Is target particular cAMP and cGMP mechanisms in SPNs subpopulations and induce specific motor effects. In this project, we plan to analyze the motor effects and physiological striatal correlates of PDE-Is in animal models of PD. Our research plan consists of two specific aims, each with two subaims, to determine behavioral and SPN responses to selective PDE-Is combining primate and rodent models of PD. We will analyze motor and SPN responses to L-Dopa under the effects of PDE-Is (PDE10A, PDE7B, and PDE9 inhibitors). These PDEs are highly expressed in the striatum and have different substrate affinities (cAMP, cGMP, or both). We will use the primate MPTP model of advanced PD for translatability of results. Hemiparkinsonian rats will also be used to refine our cell resolution in the analysis of SPN responses. We will assess parkinsonian motor impairment and LID with established methodologies, appropriate statistical power and rigorous experimental designs. We include electrophysiology (single cell recordings), intracerebral injection of drugs, and calcium indicators (fiber photometry) for analysis of SPN activity in vivo. We will also use transgenic models for assessment of responses to PDE-Is specifically in direct and indirect SPNs. Results of these experiments will shed light on DA signaling in SPN subpopulations, its regulation by PDEs, and associated motor effects of L-Dopa. Our long-term goal is to translate our findings into a new therapeutic approach to reduce aberrant DA signals in SPNs, and improve motor responses to L-Dopa therapy in PD. To this end, we expect to generate significant data with the proposed novel studies of PDE function in PD models.