Control of Glutamatergic Transmission by Acetylcholine Release in Striatum

描述(申请人提供)：纹状体是基底节的主要输入，基底节是参与启动自主运动和运动学习的结构集合。这种结构与许多运动和认知障碍有关。纹状体的主要输出是通过GABA能中棘神经元(MSN)。纹状体的胆碱能中间神经元(CINs)强直地放电，为纹状体提供神经调节剂乙酰胆碱(Ach)的唯一来源。在体外，Ach突触前抑制MSN中的皮质纹状体EPSCs。这为MSN活动的监管提供了一个强有力的机会。然而，很难评估CIN激活在这种抑制中的作用。此外，CIN被认为与体内报道的紧张性活动神经元(TAN)相对应。这些细胞对奖赏刺激和预测奖赏的刺激短暂停止放电，这表明这种暂停可能会减少Ach解除这种抑制。在这个项目中，我们试图在体外和体内将CINs的活性与MSN放电和皮质纹状体EPSCs的变化联系起来。我们使用病毒传递的光激活的膜蛋白、通道视紫红质(ChR2)和卤视紫红质(HR)来选择性地控制CIN的激活。我们已经证实，我们可以在体内和体外控制CIN的激发。我们现在可以研究CIN动作电位的时间和它们的放电频率如何影响急性脑片中MSN中的EPSCs。而且，有了HR，我们现在可以短暂地暂停纹状体中的CIN。我们将观察皮质纹状体EPSCs的任何变化，使我们能够对TAN停顿的功能做出预测。此外，使用植入的光纤和体内记录设备，我们可以在体内激活和暂停CIN。通过将可唤起的CIN与明显的TAN进行比较，我们可以确定CIN是否实际上是TAN。通过记录周围MSN的活动，我们可以确定CIN活动或暂停对自发和皮质驱动活动的净影响。这种方法可以第一次有机会观察胆碱能神经元间活动的影响，并第一次洞察Tan放电中行为上重要的停顿的功能。 公共卫生相关性：纹状体中的乙酰胆碱与自主运动和联想学习密切相关。然而，这种控制的机制还不是很清楚。我们在这项提议中开发的新技术将有助于我们理解乙酰胆碱释放如何控制其他细胞的行为，有助于我们理解正常认知以及帕金森氏症、阿尔茨海默病、亨廷顿病和精神分裂症等大脑疾病的病理生理学。

DESCRIPTION (provided by applicant): The striatum is the primary input to the basal ganglia, a collection of structures involved in initiation of voluntary movements and motor learning. This structure is involved in many movement and cognitive disorders. The principle output of striatum is through the GABAergic medium spiny neurons (MSNs). Cholinergic interneurons (CINs) of the striatum fire tonically and provide the sole source of the neuromodulator acetylcholine (Ach) to the striatum. In vitro, Ach presynaptically inhibits corticostriatal EPSCs in MSNs. This provides a powerful opportunity for regulation of MSN activity. However, it has been difficult to assess the role of CIN firing on this inhibition. Furthermore, CINs are thought to correspond to tonically active neurons (TANs) reported in vivo. These cells briefly cease firing to rewarding stimuli and stimuli that predict reward, suggesting the possibility that this pause reduces Ach relieving this inhibition. In this project we seek to link the activity of CINs to changes in MSN firing and corticostriatal EPSCs both in vitro and in vivo. We selectively control the firing of CINs using virally delivered light activated membrane proteins, channelrhodopsin (ChR2) and halorhodopsin (HR). We have validated that we can control the firing of CINs in vivo and in vitro. We can now investigate how both the timing of CIN action potential and their firing rate affects EPSCs in MSNs in the acute slice. And, with HR we now have the ability to briefly pause CINs in striatum. We will observe any changes to corticostriatal EPSCs, allowing us to make predictions on the function of TAN pauses. Additionally, using implanted fiberoptics and in vivo recording devices we can activate and pause CINs in vivo. By comparing evocable CINs to apparent TANs we can identify if CINs are in fact TANs. And by recording the activity of the surrounding MSNs we can identify the net effect of CIN activity or pause on spontaneous and cortically driven activity. This approach allows the first opportunity to observe the effects of cholinergic interneuron activity, and provides the first insight to a function of the behaviorally important pause in TAN firing. PUBLIC HEALTH RELEVANCE: Acetylcholine in striatum is critically involved in voluntary movement and associative learning. However, the mechanisms of this control are not well understood. The new techniques that we develop in this proposal will help us understand how acetylcholine release controls the behaviors of other cells, aiding in our understanding of normal cognition as well as the pathophysiology of brain disorders such as Parkinson's Disease, Alzheimer's Disease, Huntington's Disease, and Schizophrenia.