Cannabinoid Modulation of Recovery from HIV-Associated Synaptic Toxicity

描述(申请人提供)：在许多神经退行性疾病，包括HIV-1相关性痴呆(HAD)中，树突形态的变化，如树突修剪，在神经细胞死亡之前。与树突变性相关的突触连接的丧失与这些疾病的认知能力下降有关。抗逆转录病毒治疗最初改善了HAD患者的神经认知功能。初步研究通过成像支架蛋白PSD95与增强型绿色荧光蛋白(PSD95-EGFP)融合的簇来量化在原代培养的大鼠海马神经元中完整的突触后密度(PSD)。这种独特的基于成像的分析方法使相同海马神经元之间的突触连接数量能够随着时间的推移而被记录下来。HIV-1蛋白和兴奋性毒素在不会导致明显神经元死亡的浓度下导致PSD95-EGFP斑点的显著丢失。PSD丢失先于细胞死亡，并且是可逆的。突触活动是突触发育和稳定所必需的，突触和大麻素是艾滋病患者临床上非法使用的药物，调节兴奋性神经传递和兴奋性毒性。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得到验证。将记录毒素清除后PSD95-EGFP斑点恢复的详细时间进程，并确定药物阻断兴奋性突触传递的效果。用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来评价不同程度的CB1受体激活和内源性大麻素对PSD恢复的作用。大麻素受体激动剂预计会削弱神经元在神经毒性损伤后重新整合到突触网络的能力。如果大麻素抑制突触恢复，这些研究将告诫HAD患者不要娱乐地使用大麻素或将其用作止吐和食欲刺激剂。该项目可能为未来评估滥用药物对HIV-1感染中枢神经系统后神经功能恢复的影响提供基础。

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.