Pharmacological modulation of synapses and cognition during HIV-1 neurotoxicity

描述(申请人提供)：在许多神经退行性疾病，包括HIV-1相关的神经认知障碍(HAND)中，树突状修剪等树突形态的变化先于细胞死亡。树突状退行性变与手部认知能力下降有关。建立了一种基于共聚焦成像的检测完整突触后密度(PSD)的方法，该方法基于对融合到绿色荧光蛋白(PSD95-GFP)的支架蛋白(PSD95-GFP)簇的检测。在神经元培养中，PSD95-GFP斑点在暴露于HIV-1感染细胞释放的因子后丢失，包括HIV-1蛋白TAT和gp120。HIV-1神经毒素引起的PSD丢失是可逆的。这一建议将在神经艾滋病小鼠模型中将突触的丢失和恢复与认知功能联系起来。在体内，多光子成像将跟踪HIV-1蛋白表达期间的PSD95-GFP斑点，行为测试将监测认知功能。第一个目标是将HIV-1蛋白诱导的突触丢失和恢复与认知能力联系起来。异丙苯地尔是一种对含有NR2B的NMDA受体具有选择性的拮抗剂，它能诱导体外暴露于HIV-1蛋白TAT后丢失的突触恢复。目前尚不清楚的是，突触是否会在体内恢复，如果可以，认知功能是否会改善。在可诱导启动子的控制下表达TAT的转基因小鼠在诱导后会出现突触退化和认知能力下降。假设伊芬地尔将唤起表达TAT的动物丢失的突触的恢复，以及突触的恢复与认知功能的改善相关，这一假设将得到验证。预期的结果可能会为药物引起的突触数量变化预测认知功能变化的原理提供证据。第二个目的是确定大麻类药物对HIV-1蛋白诱导的突触和认知变化的影响。大麻类药物是临床上广泛使用的艾滋病患者非法使用的药物。突触的丢失和恢复在体外是一个受大麻类物质影响的动态过程。在HIV-1模型中，大麻类物质对认知功能的影响尚不清楚。针对大麻素受体亚型的激动剂将在表达HIV-1蛋白gp120或Tat的转基因小鼠身上进行测试。CB2激动剂JWH-133预计将改善表达gp120的小鼠的认知能力。相反，CB1激动剂花生四烯基-2‘-氯乙胺(ACEA)预计会损害异丙苯地尔诱导的突触恢复，并限制表达TAT的小鼠的认知改善。如果大麻类药物损害突触和认知恢复，这一结果将告诫手部疾病患者不要娱乐地使用大麻类药物或将其用作止吐和食欲刺激剂。体内多光子成像在将药物对突触结构的影响与其对行为的影响联系起来方面具有潜在的广泛应用。该项目将为指导药物的开发以改善手部患者的功能提供基础，并将确定滥用药物可能与突触的形成和丢失相互作用的部位。

DESCRIPTION (provided by applicant): Changes in dendritic morphology such as dendritic pruning precede cell death in many neurodegenerative disorders, including HIV-1-associated neurocognitive disorders (HAND). Dendritic degeneration correlates with cognitive decline in HAND. A confocal imaging-based assay was developed to detect intact postsynaptic densities (PSDs) based on detection of clusters of the scaffolding protein PSD95 fused to green fluorescent protein (PSD95-GFP). In neuronal cultures, PSD95-GFP puncta were lost following exposure to factors released by HIV-1 infected cells including the HIV-1 proteins Tat and gp120. PSD loss induced by HIV-1 neurotoxins is reversible. This proposal will relate the loss and recovery of synapses to cognitive function in mouse models of neuroAIDS. In vivo multiphoton imaging will track PSD95-GFP puncta during expression of HIV-1 proteins and behavioral tests will monitor cognitive function. The first aim is to relate HIV-1 protein induced synapse loss and recovery to cognitive performance. Treatment with ifenprodil, an antagonist selective for NR2B-containing NMDA receptors, induced the recovery of synapses lost following in vitro exposure to the HIV-1 protein Tat. What remains unclear is whether synapses recover in vivo and if they do, whether cognitive function improves. Transgenic mice that express Tat under the control of an inducible promoter exhibit synaptic degeneration and cognitive decline following induction. The hypothesis that ifenprodil will evoke recovery of synapses lost in Tat-expressing animals and that synaptic recovery will correlate with improved cognitive function will be tested. Anticipated results may provide proof of the principle that drug-induced changes in synaptic number predict changes in cognitive function. The second aim is to determine the effects of cannabinoids, drugs given to AIDS patients clinically and widely used illicitly, on the synaptic and cognitive changes induced by HIV-1 proteins. Synapse loss and recovery is a dynamic process influenced by cannabinoids in vitro. The effects of cannabinoids on cognitive function in HIV-1 models are unknown. Agonists selective for cannabinoid receptor subtypes will be tested in transgenic mice expressing the HIV-1 proteins gp120 or Tat. The CB2 agonist JWH-133 is predicted to improve cognition in gp120- expressing mice. In contrast, the CB1 agonist arachidonyl-2'-chloroethylamide (ACEA) is predicted to impair ifenprodil-induced synapse recovery and limit cognitive improvement in Tat-expressing mice. If cannabinoids impair synaptic and cognitive recovery, this result would caution against recreational use of cannabinoids or their use as antiemetics and appetite stimulants in patients with HAND. In vivo multiphoton imaging has potentially broad applications for relating the effects of drugs on synaptic structure to their effects on behavior. This project will provide a foundation to guide th development of drugs to improve function in HAND patients and will identify sites where drugs of abuse might interact with the formation and loss of synapses.