Psychostimulant Effects on Striatal Signaling

描述（由申请人提供）：本提案的总体假设是纹状体中BDNF/TrkB和GPCR信号之间的相互作用对于大脑对安非他明（AMPH）引起的过量多巴胺能和谷氨酸神经传递的反应能力至关重要。与介导对兴奋剂的精神运动反应的基因/蛋白质一起，调节反应幅度和持续时间的内源性抑制系统被激活。例如，由脑源性神经营养因子（BDNF）激活的g蛋白偶联受体（gpcr）、GABAB、NK-1、mu阿片受体和delta阿片受体以及酪氨酸激酶受体TrkB调节局部纹状体网络。此外，利用cDNA阵列分析，我们已经确定了编码细胞内信号蛋白的基因，这些蛋白被急性安非他明上调或下调。其中包括血清和糖皮质激素调节激酶1 （SGK1）和g蛋白信号传导调节因子4 （RGS4）。这些基因和蛋白质的改变表明纹状体对初始、中等剂量的AMPH有反应，具有强大的补偿机制，旨在使网络恢复稳态。在这个竞争性更新的目的1中，纹状体PIS激酶调节的级联反应对急性和重复AMPH效应的贡献将被研究。大鼠将被注入抑制GPCR信号选择性方面的药物，以研究它们是否有助于纹状体对急性AMPH的行为和神经化学反应。评估细胞核和细胞质pi3激酶活性以及磷酸化蛋白、ERK、Akt/PKB和SGK1的变化。在Aim 2中，纹状体RGS4信号对急性和重复AMPH效应的贡献将被研究。RGS4的亚细胞定位以及HSV-RGS4过表达对I组mGluRs和Homer 2以及核和细胞质ERK和pi3激酶调节的纹状体磷酸化蛋白的影响将被确定。此外，在选择性mGluR受体刺激后，RGS4与I组mGluRs和Homer 2的关联变化将被检测。在Aim 3中，纹状体BDNF/trkB信号对急性和重复AMPH效应的贡献将被研究。在AMPH后的不同时间检测皮质BDNF mRNA、皮质和纹状体BDNF和磷酸化trkb蛋白水平。此外，大鼠将被注入抑制TrkB信号传导的药物，以研究BDNF/TrkB是否有助于AMPH引发的纹状体PIS激酶调节级联反应（SGK1和Akt/PKB）的变化。识别和增强纹状体内稳态机制的振幅和持续时间，有可能针对新的神经信号系统进行药物开发，以治疗精神兴奋剂滥用和改善公众健康。

DESCRIPTION (provided by applicant): The overall hypothesis of this proposal is that interactions between BDNF/TrkB and GPCR signaling in the striatum are critical to the brain's ability to respond to excessive dopaminergic and glutamatergic neurotransmission caused by amphetamine (AMPH) administration. Along with genes/proteins that mediate the psychomotor response to stimulants, endogenous inhibitory systems that modulate the amplitude and duration of the response are activated. For example, the G-protein-coupled receptors (GPCRs), GABAB, NK-1, mu opioid and delta opioid receptors, as well as the tyrosine kinase receptor, TrkB, activated by brain-derived neurotrophic factor (BDNF), regulate the local striatal network. Further, using cDNA array analyses, we have identified genes coding for intracellular signaling proteins that are up- or downregulated by acute amphetamine. These include the Serum and Glucocorticoid-Regulated Kinase 1 (SGK1) and the Regulator of G-protein Signalling 4 (RGS4). Alteration of these genes and proteins suggests that the striatum responds to an initial, moderate dose of AMPH with a robust repertoire of compensatory mechanisms aimed at bringing the network back to homeostasis. In Aim 1 of this competitve renewal, the contribution of striatal PIS kinase-regulated cascades to acute and repeated AMPH effects will be investigated. Rats will be infused intrastriatally with drugs that inhibit selective aspects of GPCR signaling to investigate whether they contribute to the behavioral and neurochemical responses of the striatum to acute AMPH. Changes in nuclear and cytoplasmic PI3-kinase activity and the phospho-proteins, ERK, Akt/PKB and SGK1 will be evaluated. In Aim 2, the contribution of striatal RGS4 signaling to acute and repeated AMPH effects will be investigated. The subcellular localization of RGS4 and the effects of HSV-RGS4 overexpression on Group I mGluRs and Homer 2 as well as nuclear and cytoplasmic ERK and PI3-kinase regulated phosphoproteins in the striatum will be determined. Further, changes in the association of RGS4 with Group I mGluRs and Homer 2 will be examined after selective mGluR receptor stimulation. In Aim 3, the contribution of striatal BDNF/trkB signaling to acute and repeated AMPH effects will be investigated. Cortical BDNF mRNA and cortical and striatal BDNF and phospho-TrkB protein levels will be examined at different times after AMPH. In addition, rats will be infused intrastriatally with drugs that inhibit TrkB signaling to investigate whether BDNF/TrkB contributes to the changes in striatal PIS kinase-regulated cascades (SGK1 and Akt/PKB) elicited by AMPH. Identifying and enhancing the amplitude and duration of homeostatic mechanisms in the striatum has the potential of targeting novel neuronal signaling systems for medicinal development to treat psychostimulant abuse and to improve public health.