TRANSPORTER REGULATION OF GABAB-MEDIATED TRANSMISSION IN THE THALAMUS

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 从神经递质释放到受体定位到神经递质摄取机制的许多因素都会影响GABA介导的突触抑制，特别是对代谢型（GABA介导的）反应。由于突触后GABAB受体主要位于突触部位之外（即突触外），因此假设GABA转运蛋白（GATs），其功能是清除细胞外GABA，限制GABA溢出的程度，从而限制GABAB受体激活。为了更好地了解GATs如何调节GABA溢出，我们正在研究两种GATs GAT1和GAT3在定义大鼠丘脑中GABAB IPSC特征中的作用。我们的电生理学数据表明，GAT1和GAT3差异调节GABAB IPSC的幅度和动力学。我们的解剖学数据表明，这些不同的GAT1/3行动的结果，在亚细胞定位和密度的两个GAT的差异。具体地说，GAT1的表达主要是突触周围，而GAT3被发现在突触外和更远的突触外区域。我们开始探索这种差异定位如何影响GABAB电流。我们目前正在使用计算方法来探索GAT定位如何调节丘脑中的GABA扩散，以及这种调节如何决定GABAB IPSC的特性。具体来说，我们正在使用MCell，这是一个建模平台，它使用Monte Carlo算法跟踪三维微生理环境中扩散分子的随机性（Stiles和Bartol，2001）。我们的更简单，计算密集度较低的模型表明，差异GAT1/3定位提供了一种机制，通过该机制可以调制GABA瞬变，以实现不同的GABAB IPSC振幅和动力学变化。我们现在想在更复杂的模型中验证这些初步发现。乔尔·斯泰尔斯博士建议我们利用汉堡超级计算中心提供的资源来运行我们的新模型。因此，我们按照他的建议，申请这些资源来完成我们的项目。我们希望用户帐户马克Beenhakker和约翰Huguenard

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Many factors ranging from neurotransmitter release to receptor localization to neurotransmitter uptake mechanisms will affect GABA-mediated synaptic inhibition, especially for metabotropic (GABAB-mediated) responses. As postsynaptic GABAB receptors are localized primarily outside of synaptic sites (ie extrasynaptic), it is hypothesized that GABA transporters (GATs), which function to remove extracellular GABA, limit the extent of GABA spillover and, therefore, GABAB receptor activation. To better understand how GATs regulate GABA spillover, we are examining the roles of two GATs, GAT1 and GAT3, in defining features of GABAB IPSCs in the rat thalamus. Our electrophysiology data demonstrate that GAT1 and GAT3 differentially regulate the amplitude and kinetics of GABAB IPSCs. Our anatomical data suggest that these different GAT1/3 actions result from differences in subcellular localization and density of the two GATs. Specifically, GAT1 expression is primarily perisynaptic, while GAT3 is found in both peri- and more distal extra-synaptic regions. We are beginning to explore how such differential localization can influence GABAB currents. We are currently using computational approaches to explore how GAT localization regulates GABA diffusion in the thalamus, and how such regulation determines the properties of GABAB IPSCs. Specifically, we are using MCell, a modeling platform that tracks the stochastic nature of diffusing molecules in 3-dimensional microphysiological environments using Monte Carlo algorithms (Stiles and Bartol, 2001). Our simpler, less computationally-intensive models indicate that differential GAT1/3 localization provides a mechanism by which GABA transients can be modulated to enable distinct GABAB IPSC amplitude and kinetic changes. We now would like to verify these initial findings in more complex models. Dr. Joel Stiles suggested that we utilize resources offered by the Pittsburg Supercomputing Center to run our new models. Therefore, in following his suggestion, we are applying for these resources to complete our project. We would like user accounts for Mark Beenhakker and John Huguenard