Dopamine neurons mediate a fast excitatory signal via their glutamatergic synapses.
Dopamine neurons are thought to convey a fast, incentive salience signal, faster than can be mediated by dopamine. A resolution of this paradox may be that midbrain dopamine neurons exert fast excitatory actions. Using transgenic mice with fluorescent dopamine neurons, in which the axonal projections of the neurons are visible, we made horizontal brain slices encompassing the mesoaccumbens dopamine projection. Focal extracellular stimulation of dopamine neurons in the ventral tegmental area evoked dopamine release and early monosynaptic and late polysynaptic excitatory responses in postsynaptic nucleus accumbens neurons. Local superfusion of the ventral tegmental area with glutamate, which should activate dopamine neurons selectively, produced an increase in excitatory synaptic events. Local superfusion of the ventral tegmental area with the D2 agonist quinpirole, which should increase the threshold for dopamine neuron activation, inhibited the early response. So dopamine neurons make glutamatergic synaptic connections to accumbens neurons. We propose that dopamine neuron glutamatergic transmission may be the initial component of the incentive salience signal.
Chuhma
Nao
N
Department of Psychiatry, Columbia University, New York, New York 10032, USA.
Zhang
Hui
H
Masson
Justine
J
Zhuang
Xiaoxi
X
Sulzer
David
D
Hen
René
R
Rayport
Stephen
S
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D004298:Dopamine / Q000378:metabolism*; D018491:Dopamine Agonists / Q000494:pharmacology; D005260:Female; D017930:Genes, Reporter; D018698:Glutamic Acid / Q000378:metabolism* / Q000494:pharmacology; D006579:Heterozygote; D066298:In Vitro Techniques; D008164:Luminescent Proteins / Q000235:genetics; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009042:Motivation; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D009714:Nucleus Accumbens / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D018408:Patch-Clamp Techniques; D017448:Receptors, Dopamine D2 / Q000819:agonists; D013569:Synapses / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology*; D017557:Ventral Tegmental Area / Q000187:drug effects / Q000502:physiology
D001426:Bacterial Proteins; D018491:Dopamine Agonists; D008164:Luminescent Proteins; D017448:Receptors, Dopamine D2; C054562:yellow fluorescent protein, Bacteria; D018698:Glutamic Acid; D004298:Dopamine