Freyberg Zachary, Sonders Mark S, Aguilar Jenny I, Hiranita Takato, Karam Caline S, Flores Jorge, Pizzo Andrea B, Zhang Yuchao, Farino Zachary J, Chen Audrey, Martin Ciara A, Kopajtic Theresa A, Fei Hao, Hu Gang, Lin Yi-Ying, Mosharov Eugene V, McCabe Brian D, Freyberg Robin, Wimalasena Kandatege, Hsin Ling-Wei, Sames Dalibor, Krantz David E, Katz Jonathan L, Sulzer David, Javitch Jonathan A
Department of Psychiatry, College of Physicians &Surgeons, Columbia University, New York, New York 10032, USA.
Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York 10032, USA.
Nat Commun. 2016 Feb 16;7:10652. doi: 10.1038/ncomms10652.
Amphetamines elevate extracellular dopamine, but the underlying mechanisms remain uncertain. Here we show in rodents that acute pharmacological inhibition of the vesicular monoamine transporter (VMAT) blocks amphetamine-induced locomotion and self-administration without impacting cocaine-induced behaviours. To study VMAT's role in mediating amphetamine action in dopamine neurons, we have used novel genetic, pharmacological and optical approaches in Drosophila melanogaster. In an ex vivo whole-brain preparation, fluorescent reporters of vesicular cargo and of vesicular pH reveal that amphetamine redistributes vesicle contents and diminishes the vesicle pH-gradient responsible for dopamine uptake and retention. This amphetamine-induced deacidification requires VMAT function and results from net H(+) antiport by VMAT out of the vesicle lumen coupled to inward amphetamine transport. Amphetamine-induced vesicle deacidification also requires functional dopamine transporter (DAT) at the plasma membrane. Thus, we find that at pharmacologically relevant concentrations, amphetamines must be actively transported by DAT and VMAT in tandem to produce psychostimulant effects.
苯丙胺会提高细胞外多巴胺水平，但其潜在机制仍不明确。我们在此向啮齿动物展示，对囊泡单胺转运体（VMAT）进行急性药理学抑制会阻断苯丙胺诱导的运动和自我给药行为，而不影响可卡因诱导的行为。为了研究VMAT在介导多巴胺神经元中苯丙胺作用方面的作用，我们在黑腹果蝇中使用了新的遗传学、药理学和光学方法。在离体全脑制备中，囊泡货物和囊泡pH值的荧光报告分子显示，苯丙胺会重新分配囊泡内容物，并减少负责多巴胺摄取和保留的囊泡pH梯度。这种由苯丙胺诱导的去酸化需要VMAT功能，并且是由VMAT将H(+)从囊泡腔反向转运到细胞外，同时伴随着苯丙胺向内转运所导致的。苯丙胺诱导的囊泡去酸化还需要质膜上功能性多巴胺转运体（DAT）的参与。因此，我们发现，在药理学相关浓度下，苯丙胺必须由DAT和VMAT协同主动转运才能产生精神兴奋作用。
