Cannabinoid Modulation of Recovery from HIV-Associated Synaptic Toxicity

描述（由申请人提供）：在许多神经退行性疾病（包括HIV-1相关痴呆（HAD））中，树突形态学变化（如树突修剪）先于神经元细胞死亡。与树突变性相关的突触连接的丧失与这些疾病中的认知下降相关。抗逆转录病毒治疗最初可改善HAD患者的神经认知功能。初步研究通过成像融合增强型绿色荧光蛋白（PSD 95-EGFP）的支架蛋白PSD 95簇来量化在原代培养中生长的大鼠海马神经元中的完整突触后密度（PSD）。这种独特的基于成像的测定能够随着时间的推移记录相同海马神经元之间的突触连接的数量。HIV-1蛋白和兴奋性毒素在不能产生明显神经元死亡的浓度下引起PSD 95-EGFP斑点的显著损失。PSD损失先于细胞死亡，并且是可逆的。突触活动是突触和大麻素的发育和稳定所需的，大麻素是临床上广泛使用的艾滋病患者药物，可调节兴奋性神经传递和兴奋性毒性。将测试大麻素激动剂在暴露于兴奋性毒素或HIV蛋白后减缓突触恢复的假设。将记录除去毒素后PSD 95-EGFP斑点恢复的详细时间过程，并确定兴奋性突触传递的药理学阻断的效果。大麻素受体完全激动剂，部分激动剂？9-四氢大麻酚和受体拮抗剂将用于评估不同程度的CB 1受体活化和内源性大麻素紧张度对PSD恢复的作用。预计大麻素受体激动剂会损害神经元在神经毒性损伤后整合回突触网络的能力。如果大麻素抑制突触恢复，这些研究将警告大麻素的娱乐性使用或其作为HAD患者的止吐剂和食欲刺激剂。该项目可能为未来的研究提供基础，以评估滥用药物对中枢神经系统HIV-1感染后神经功能恢复的影响。

DESCRIPTION (provided by applicant): Changes in dendritic morphology such as dendritic pruning precede neuronal cell death in many neurodegenerative disorders, including HIV-1 associated dementia (HAD). The loss of synaptic connections associated with dendritic degeneration correlates with cognitive decline in these disorders. Antiretroviral treatment initially improves neurocognitive function in HAD patients. Preliminary studies quantified intact postsynaptic densities (PSDs) in rat hippocampal neurons grown in primary culture by imaging clusters of the scaffolding protein PSD95 fused to enhanced green fluorescent protein (PSD95-EGFP). This unique imaging based assay enables the number of synaptic connections between the same hippocampal neurons to be recorded over time. HIV-1 proteins and excitotoxins caused significant loss of PSD95-EGFP puncta at concentrations that failed to produce overt neuronal death. PSD loss preceded cell death and was reversible. Synaptic activity is required for the development and stability of synapses and cannabinoids, drugs given to AIDS patients clinically and widely used illicitly, modulate excitatory neurotransmission and excitotoxicity. The hypothesis that cannabinoid agonists slow recovery of synapses following exposure to excitotoxins or HIV proteins will be tested. A detailed time course for recovery of PSD95-EGFP puncta following removal of toxin will be recorded and the effects of pharmacological block of excitatory synaptic transmission determined. A cannabinoid receptor full agonist, the partial agonist ?9-tetrahydrocannabinol and a receptor antagonist will be used to evaluate the role of varying degrees of CB1 receptor activation and endocannabinoid tone on recovery of PSDs. Cannabinoid receptor agonists are predicted to impair the ability of neurons to integrate back into the synaptic network following neurotoxic insult. If cannabinoids inhibit synaptic recovery, these studies would caution against recreational use of cannabinoids or their use as antiemetics and appetite stimulants in patients with HAD. This project may provide a foundation for future studies to evaluate the effects of drugs of abuse on the recovery of neural function following HIV-1 infection of the central nervous system.