Role of Alpha2delta-1 in Cocaine Relapse and Gabapentin Mechanisms of Action

描述（由申请人提供）：药物成瘾是一种慢性疾病，其特征是高复发率，即使在长期戒毒后也是如此。慢性可卡因后伏隔核（NAc）突触的谷氨酸能可塑性改变被认为是复发易感性的一个关键特征。在NAc中已经确定的重要神经适应性包括前额叶皮层（PFC）释放概率的增强，谷氨酸受体组成、表达和电流的变化以及树突棘形态的改变。然而，药物诱导的NAc突触可塑性变化的潜在机制尚不完全清楚。电压门控Ca 2+通道（VGCC）辅助亚基-1被多种滥用药物的非偶然给药上调。该2¿-1亚基与VGCC的各种亚型偶联，VGCC控制神经递质释放，影响神经元兴奋性，并修饰基因转录。此外，星形胶质细胞衍生的血小板反应蛋白（TSP）蛋白与<$2 <$-1结合，通过不依赖于Ca 2+通道的机制促进兴奋性突触的形成。加巴喷丁（GBP）是-1配体，可破坏TSP和-1之间的相互作用，抑制突触形成。我的初步数据显示，可卡因自我给药后，<$2 <$1和TSP-1增加。此外，我发现，内NAc交付GBP减少可卡因诱导的恢复药物寻求。目前的提案旨在进一步阐明GBP在<$2 <$-1亚基上的作用，并确定GBP对可卡因诱导的药物寻求的作用机制。我推测，上调-1促进复发可卡因寻求自我管理后，相反，抑制-1减少可卡因诱导的复吸。我进一步假设，GBP的作用是由于其在突触前<$2 <$-1亚基的作用，以抑制由VGCC激活诱导的神经递质释放或破坏TSP蛋白的支架，从而干扰突触重塑。具体目标1：我将用反义活体吗啉代敲低<$2 <$1，以验证<$2 <$1在可卡因复吸中的作用。具体目标2：使用体内微透析，我将评估我的假设，即GBP的作用涉及抑制 通过测量GBP的反向透析在可卡因诱导的恢复期间的谷氨酸和多巴胺水平来测量神经递质释放。具体目标3：我将确定重组TSP对可卡因复吸的影响，并确定药物诱导的树突棘变化是否通过GBP或重组TSP治疗进行修饰，使用定量树突棘形态学测量。这些行为和生化研究的结果将揭示一个共同的神经生物学机制，有助于药物复吸，并澄清GBP作为一种抗成瘾剂的作用机制。

DESCRIPTION (provided by applicant): Drug addiction is a chronic disease characterized by high relapse rates, even following extended abstinence from drug use. Altered glutamatergic plasticity at nucleus accumbens (NAc) synapses after chronic cocaine is identified as a key feature underlying relapse vulnerability. Among the important neuroadaptations that have been identified in NAc are enhancement of prefrontal cortex (PFC) release probability, changes in glutamate receptor composition, expression and currents, and alterations in dendritic spine morphology. However, the underlying mechanisms of drug-induced changes in NAc synaptic plasticity are not fully known. The voltage gated Ca2+ channel (VGCC) auxiliary subunit ¿2¿-1 is upregulated by non-contingent administration of multiple drugs of abuse. The ¿2¿-1 subunit couples to various subtypes of VGCCs which control neurotransmitter release, influence neuronal excitability, and modify gene transcription. In addition, astrocyte-derived thrombospondin (TSP) proteins bind to ¿2¿-1 facilitating the formation of excitatory synapses through a Ca2+ channel-independent mechanism. Gabapentin (GBP), an ¿2¿-1 ligand, disrupts the interaction between TSP and ¿2¿-1 and inhibits synapse formation. My preliminary data show that ¿2¿-1 and TSP-1 are increased after extinction from cocaine self-administration. Moreover, I find that intra-NAc delivery of GBP decreases cocaine-induced reinstatement of drug-seeking. The current proposal is aimed at further clarifying GBP's actions at the ¿2¿-1 subunit and determining the mechanism of action of GBP on cocaine-induced drug- seeking. I hypothesize that upregulated ¿2¿-1 promotes relapse to cocaine-seeking after self-administration, and conversely, inhibiting ¿2¿-1 reduces cocaine-induced reinstatement. I further hypothesize that GBP's effects are due to its actions at presynaptic ¿2¿-1 subunits to inhibit neurotransmitter release induced by VGCC activation OR disrupting the scaffolding of TSP proteins thereby interfering with synaptic remodeling. Specific Aim 1: I will knockdown ¿2¿-1 with anti-sense vivo-morpholino to validate the role of ¿2¿-1 in cocaine reinstatement. Specific Aim 2: Using in vivo microdialysis, I will evaluate my hypothesis that GBP's actions involve inhibition of neurotransmitter release by measuring levels of glutamate and dopamine during cocaine- induced reinstatement with reverse-dialysis of GBP. Specific Aim 3: I will determine the effects of recombinant TSP on cocaine reinstatement and identify whether drug-induced dendritic spine changes are modified by GBP or recombinant TSP treatment using quantitative dendritic spine morphology measurements. Results from these behavioral and biochemical studies will shed light on a shared neurobiological mechanism contributing to drug relapse and clarify the mechanism of action of GBP as an anti-addiction agent.