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

描述（由申请人提供）：药物成瘾是一种以高复发率为特征的慢性疾病，即使在长期戒除药物使用后也是如此。慢性可卡因后伏隔核（NAc）突触谷氨酸能可塑性的改变被确定为复发易感性的关键特征。在NAc中发现的重要神经适应包括前额叶皮质（PFC）释放概率的增强，谷氨酸受体组成、表达和电流的改变以及树突棘形态的改变。然而，药物诱导NAc突触可塑性改变的潜在机制尚不完全清楚。电压门控Ca2+通道（VGCC）辅助亚基¿2¿-1被非偶然的多种药物滥用管理上调。- 2 -1亚基偶联到各种VGCCs亚型，控制神经递质释放，影响神经元兴奋性，并修改基因转录。此外，星形胶质细胞衍生的血栓反应蛋白（TSP）蛋白通过Ca2+通道独立的机制与¿2¿-1结合，促进兴奋性突触的形成。加巴喷丁（GBP）是一种¿2¿-1配体，破坏TSP和¿2¿-1之间的相互作用，抑制突触的形成。我的初步数据显示，可卡因自我服用后，¿2¿1和TSP-1消失后增加。此外，我发现nac内递送GBP可以减少可卡因诱导的药物寻求恢复。目前的提案旨在进一步明确GBP在¿2¿1亚基上的作用，并确定GBP对可卡因诱导的寻药行为的作用机制。我推测，在自我给药后，上调的¿2 -1会促进可卡因寻求的复发，相反，抑制¿2 -1会减少可卡因诱导的恢复。我进一步假设GBP的作用是由于其作用于突触前的¿2¿1亚基，抑制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：我将用反义体内morpholino击倒¿2¿-1，验证¿2¿-1在可卡因恢复中的作用。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

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.