TRANSPORTER REGULATION OF GABAB-MEDIATED TRANSMISSION IN THE THALAMUS

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 从神经递质释放到受体定位，再到神经递质摄取机制，许多因素都会影响GABA介导的突触抑制，尤其是GABAB介导的代谢性反应。由于突触后的GABAB受体主要定位于突触外(即突触外)，因此推测GABA转运体(GATS)具有清除细胞外GABA的功能，从而限制了GABA溢出的程度，从而限制了GABAB受体的激活。为了更好地了解GATS如何调节GABA溢出，我们正在研究两个GAT1和GAT3在定义GABAB ipscs在大鼠丘脑中的功能中的作用。我们的电生理学数据表明，GAT1和GAT3对GABAB ipscs的幅度和动力学有不同的调节作用。我们的解剖学数据表明，这些不同的GAT1/3作用是由于两个GAT的亚细胞定位和密度的不同造成的。具体地说，GAT1主要在突触周围表达，而GAT3在突触周围和更远端的突触外区域都有表达。我们开始探索这种差异局部化如何影响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GABA的扩散，以及这种调节如何决定GABAB iPSCs的性质。具体地说，我们使用的是Mcell，这是一个使用蒙特卡洛算法跟踪三维微生理环境中扩散分子的随机性质的建模平台(Siles和Bartol，2001)。我们更简单、计算密集度较低的模型表明，差异GAT1/3局部化提供了一种机制，通过该机制可以调制GABA瞬变，以实现不同的GABAB iPSC幅度和动力学变化。我们现在想要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匹兹堡超级计算中心提供的资源来运行我们的新模型。因此，按照他的建议，我们正在申请这些资源来完成我们的项目。我们想要Mark Beenhakker和John Huguenard的用户帐户

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. 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