CRCNS: Spatio-temporal Dynamics of Dopamine Activated 2nd Messenger Pathway

描述（由申请人提供）：拟议研究的长期目标是了解慢性酒精戒断如何改变纹状体学习机制，从而促进成瘾的行为方面。我们的中心假设是，从乙醇中撤出改变了突触可塑性的平衡，从长时程增强（LTP）到长时程抑制（LTD）。为了实现我们的目标，所提出的研究采用了一组新颖的、相互关联的实验和模型模拟来表征控制纹状体突触可塑性的突触前机制和突触后信号传导通路。第一个目的是研究细胞内钙离子的时空模式如何将不同的突触输入模式转化为纹状体突触可塑性的不同方向。树突和棘的双光子钙成像将测量响应于我们最近开发的θ爆发LTP诱导方案的钙动力学，并将其与响应于高频LTD诱导方案的钙动力学进行比较。使用创新的空间随机反应扩散软件NeuroRD对这些钙动力学进行模型模拟，将评估哪些钙激活信号通路区分钙升高的时空模式。第二个目的是研究神经调质释放的时间模式如何与皮层神经元能输入相互作用，以控制增强与抑郁的发展。一个实验部分使用通道视紫红质和盐视紫红质来控制乙酰胆碱释放的时间模式，以测试以下假设：在100 Hz皮质-纹状体刺激期间乙酰胆碱释放的短暂减少会产生LTD，而乙酰胆碱释放的瞬时增加阻断了LTD。第二个实验部分测量多巴胺浓度，以检验θ爆发刺激增强多巴胺释放的假设，100 Hz刺激。建模组件模拟由神经调节剂释放的这些不同时间模式激活的突触后信号传导途径以及钙动力学，以识别哪些可塑性相关激酶或磷酸酶将LTP与LTD诱导方案区分开。模型预测进行了实验测试，并验证模型将用于评估空间特异性和方向的突触可塑性，以响应现实的皮层输入trins。未来的研究将通过实验测试我们关于酒精戒断对突触可塑性影响的中心假设，并将使用经验证的模型通过模拟“戒断”模型来研究酒精对突触可塑性的影响，该模型包括酒精对单个分子（例如腺苷酸环化酶，NMDAR通道）和神经调质释放的影响。

DESCRIPTION (provided by applicant): The long term objectives of the proposed research are to understand how withdrawal from chronic alcohol alters striatal learning mechanisms thereby contributing to behavioral aspects of addiction. Our central hypothesis is that withdrawal from ethanol alters the balance of synaptic plasticity from long term potentiation (LTP) to long term depression (LTD). To accomplish our goal, the proposed research employs a novel, inter-related set of experiments and model simulations to characterize both pre- synaptic mechanisms and post-synaptic signaling pathways which control striatal synaptic plasticity. The first aim investigates how spatio-temporal patterns of intracellular calcium translate different synaptic input patterns into different directions of striatal synaptic plasticity. Two-photon calcim imaging of dendrites and spines will measure the calcium dynamics in response to our recently developed, theta burst LTP induction protocol and compare this with the calcium dynamics in response to a high frequency, LTD induction protocol. Model simulations of these calcium dynamics implemented using the innovative, spatial, stochastic reaction-diffusion software NeuroRD will evaluate which calcium activated signaling pathways discriminate spatio-temporal patterns of calcium elevation. The second aim investigates how temporal patterns of neuromodulator release interact with cortical glutamatergic inputs to control the development of potentiation versus depression. One experimental component uses channelrhodopsin and halorhodopsin to control temporal patterns of acetylchloline release to test the hypotheses that a transient decrease in acetylcholine release during the 100 Hz cortico-striatal stimulation produces LTD, whereas a transient increase in acetylcholine release blocks LTD. A second experimental component measures dopamine concentration to test the hypothesis that theta burst stimulation enhances release of dopamine as compared to 100 Hz stimulation. The modeling component simulates the post-synaptic signaling pathways activated by these various temporal patterns of neuromodulator release together with calcium dynamics to identify which plasticity related kinases or phosphatases discriminate LTP from LTD induction protocols. Model predictions are tested experimentally, and the validated model will be used to evaluate spatial specificity and direction of synaptic plasticity in response to realistic cortical input trins. Future research will experimentally test our central hypothesis on the effect of alcohol withdrawal on synaptic plasticity, and will use the validated model to investigate the effect of alcohol on synaptic plasticity by simulations of a "withdrawn" model which includes the effect of alcohol on both individual molecules (e.g. adenylyl cyclase, NMDAR channels) and neuromodulator release.