Cocaine abuse and plasticity in the lateral hypothalamus

 描述（由申请人提供）：成瘾是一种慢性复发性疾病，其特征是强迫性药物摄入和戒烟后易复发。在可卡因摄入量逐渐增加的大鼠中，我们观察到了下丘脑内侧（LH）回路重塑的基因表达证据，这可能有助于向强迫性药物摄入和成瘾的转变。特别是，开发的强制性可卡因摄入量在扩展访问条件下的特点是增加的基因表达的突触前和突触后蛋白，提示LH内在电路的结构重组。对这些基因表达数据的仔细分析表明，目前尖端基础研究奖（CEBRA）资助提案背后的假设是，这种变化是由谷氨酸驱动的代谢可塑性引起的。事实上，我们观察到，神经胶质产电Na+依赖性谷氨酸转运蛋白增加的LH的历史升级（强迫性）可卡因自我管理。星形胶质细胞对谷氨酸的钠偶联再摄取导致Na+/K+ ATP酶的激活，进而触发星形胶质细胞的葡萄糖摄取和糖原分解，导致乳酸的产生和释放到细胞外空间中。因此，我们观察到可卡因自我给药导致细胞外乳酸水平增加，并且伴随着神经胶质产电Na+依赖性谷氨酸转运蛋白表达增加，参与星形胶质细胞和神经元之间乳酸转运的几个基因也显示出在具有递增可卡因自我给药史的大鼠的LH中表达增加。为了检验本假设，在具体目标1，我们将调查功能适应下丘脑外侧的补丁全细胞记录之前和之后的过渡到强迫性可卡因自我管理食欲素和MCH神经元。即使是轻微的代谢操作，如过夜的食物剥夺，诱导食欲素神经元的结构和功能突触的变化，被动可卡因管理。在具体目标2中，我们将研究通过在星形胶质细胞选择性启动子下递送过表达星形胶质细胞谷氨酸转运蛋白GLT 1的腺相关病毒载体（AAV）来操纵LH中的星形胶质细胞谷氨酸再摄取对食欲素和MCH神经元的电生理学的影响。这种方法显示出作为癫痫的实验性基因治疗策略的前景。

 DESCRIPTION (provided by applicant): Addiction is a chronic, relapsing disorder characterized by compulsive drug intake and vulnerability to relapse after cessation. In rats with an escalated pattern of cocaine intake, we observed gene expression evidence of remodeling of intrinsic lateral hypothalamic (LH) circuitry, which could contribute to the transition to compulsie drug taking and addiction. In particular, development of compulsive cocaine intake under extended access conditions was characterized by increased expression of genes for pre- and post-synaptic proteins, suggestive of structural reorganization of LH intrinsic circuitry. Careful analysis of these gene expression data suggests the hypothesis behind the present Cutting-Edge Basic Research Awards (CEBRA) grant proposal that such changes are brought about by glutamate-driven metabolic plasticity. In fact, we observed that glial electrogenic Na+ dependent glutamate transporters were increased in the LH of rats with histories of escalated (compulsive) cocaine self-administration. Sodium-coupled re-uptake of glutamate by astrocytes results in the activation of the Na+/K+ ATPase triggering, in turn, glucose uptake by astrocytes and glycogenolysis leading to the production and release of lactate into the extracellular space. Consistently, we observed that cocaine self- administration results in increased extracellular lactate levels and that concomitantly with increased expression of the glial electrogenic Na+ dependent glutamate transporters, several genes involved in lactate transport between astrocytes and neurons also showed increased expression in the LH of rats with histories of escalated cocaine self-administration. To test the present hypothesis, in Specific Aim 1 we will investigate functional adaptations in the lateral hypothalamus by patch-whole cell recording before and after the transition to compulsive cocaine self-administration in orexin and MCH neurons. Even minor metabolic manipulations, such as overnight food deprivation, induce structural and functional synaptic changes in orexin neurons as does passive cocaine administration. In Specific Aim 2 we will investigate the effect of manipulating astrocytic glutamate re-uptake in the LH on the electrophysiology of orexin and MCH neurons by delivery of an adeno- associated viral vector (AAV) over-expressing the astrocyte glutamate transporter GLT1 under an astrocyte- selective promoter. This approach showed promise as an experimental gene therapy strategy for epilepsy.