Vesicular Glutamate Transport Promotes Dopamine Storage and Glutamate Corelease In Vivo

• DOI: 10.1016/j.neuron.2010.02.012
• Publication Date: 2010-03-11T09:56:13Z
• Authors: Thomas S. Hnasko; Nao Chuhma; Hui Zhang; Germaine Y. Goh; David Sulzer; Richard D. Palmiter; Stephen Rayport; Robert H. Edwards
• Keywords: Neuroscience(all); Dopamine; Green Fluorescent Proteins; Glutamic Acid; In Vitro Techniques; MOLNEURO; Choline; Membrane Potentials; Mice; 03 medical and health sciences; Adenosine Triphosphate; Catecholamines; Chlorides; Cocaine; Dopamine Uptake Inhibitors; Animals; Humans; Cell Line, Transformed; Analysis of Variance; 0303 health sciences; Hydrogen-Ion Concentration; Corpus Striatum; Luminescent Proteins; Animals, Newborn; CELLBIO

Dopamine neurons in the ventral tegmental area (VTA) play an important role in the motivational systems underlying drug addiction, and recent work has suggested that they also release the excitatory neurotransmitter glutamate. To assess a physiological role for glutamate corelease, we disrupted the expression of vesicular glutamate transporter 2 selectively in dopamine neurons. The conditional knockout abolishes glutamate release from midbrain dopamine neurons in culture and severely reduces their excitatory synaptic output in mesoaccumbens slices. Baseline motor behavior is not affected, but stimulation of locomotor activity by cocaine is impaired, apparently through a selective reduction of dopamine stores in the projection of VTA neurons to ventral striatum. Glutamate co-entry promotes monoamine storage by increasing the pH gradient that drives vesicular monoamine transport. Remarkably, low concentrations of glutamate acidify synaptic vesicles more slowly but to a greater extent than equimolar Cl(-), indicating a distinct, presynaptic mechanism to regulate quantal size.