title: Phasic dopamine release drives rapid activation of striatal D2-receptors.
abstract: Striatal dopamine transmission underlies numerous goal-directed behaviors. Medium spiny neurons (MSNs) are a major target of dopamine in the striatum. However, as dopamine does not directly evoke a synaptic event in MSNs, the time course of dopamine signaling in these cells remains unclear. To examine how dopamine release activates D2-receptors on MSNs, G protein activated inwardly rectifying potassium (GIRK2; Kir 3.2) channels were virally overexpressed in the striatum, and the resulting outward currents were used as a sensor of D2-receptor activation. Electrical and optogenetic stimulation of dopamine terminals evoked robust D2-receptor inhibitory postsynaptic currents (IPSCs) in GIRK2-expressing MSNs that occurred in under a second. Evoked D2-IPSCs could be driven by repetitive stimulation and were not occluded by background dopamine tone. Together, the results indicate that D2-receptors on MSNs exhibit functional low affinity and suggest that striatal D2-receptors can encode both tonic and phasic dopamine signals.
authors.affiliation: Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH 44106-4970, USA.
authors.forename: Pamela F
authors.initials: PF
authors.lastname: Marcott
authors.affiliation: Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106-4970, USA.
authors.forename: Aphroditi A
authors.initials: AA
authors.lastname: Mamaligas
authors.affiliation: Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH 44106-4970, USA; Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106-4970, USA. Electronic address: cpf21@case.edu.
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Ford
mesh_terms: D000818:Animals; D003342:Corpus Striatum / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D053444:Inhibitory Postsynaptic Potentials / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009474:Neurons / Q000378:metabolism; D009924:Organ Culture Techniques; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D013997:Time Factors
chemical_list: D017448:Receptors, Dopamine D2; D004298:Dopamine