Cocaine abuse and plasticity in the lateral hypothalamus

 描述(申请人提供)：上瘾是一种慢性、复发性疾病，特征是强制吸食药物，并在戒烟后容易复发。在可卡因摄入模式升级的大鼠中，我们观察到基因表达证据表明，固有的下丘脑外侧回路(LH)重塑，这可能有助于向强制服药和成瘾的转变。特别是，在延长接触条件下，强迫性可卡因摄入的特征是突触前和突触后蛋白基因表达增加，这暗示着促黄体生成素内在回路的结构重组。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)拨款背后的假设是，这种变化是由谷氨酸驱动的代谢可塑性带来的。事实上，我们观察到，在有强制给药史的大鼠的黄体生成素中，神经胶质细胞产生的Na+依赖的谷氨酸转运体增加。钠偶联的星形胶质细胞重新摄取谷氨酸导致Na+/K+ATPase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。我们一致地观察到，可卡因自我给药导致细胞外乳酸水平增加，伴随着胶质细胞产生的Na+依赖的谷氨酸转运体表达的增加，几个参与星形胶质细胞和神经元之间乳酸运输的基因在有可卡因自我给药历史的大鼠的黄体中也显示了高表达。为了验证这一假说，在特定的目标1中，我们将通过对食欲素和MCH神经元过渡到强制给药可卡因前后的全细胞膜片记录来研究下丘脑外侧区的功能适应。就像被动注射可卡因一样，即使是较小的代谢操作，如过夜的食物剥夺，也会导致食欲素神经元的结构和功能上的突触变化。在特定的目标2中，我们将通过在星形胶质细胞选择性启动子下过表达星形胶质细胞谷氨酸转运体GLT1的腺相关病毒载体(AAV)来研究操纵星形胶质细胞谷氨酸在黄体生成素重新摄取对食欲素和MCH神经元电生理的影响。这一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.