title: Selective Ablation of GIRK Channels in Dopamine Neurons Alters Behavioral Effects of Cocaine in Mice.
abstract: The increase in dopamine (DA) neurotransmission stimulated by in vivo cocaine exposure is tempered by G protein-dependent inhibitory feedback mechanisms in DA neurons of the ventral tegmental area (VTA). G protein-gated inwardly rectifying K+(GIRK/Kir3) channels mediate the direct inhibitory effect of GABABreceptor (GABABR) and D2DA receptor (D2R) activation in VTA DA neurons. Here we examined the effect of the DA neuron-specific loss of GIRK channels on D2R-dependent regulation of VTA DA neuron excitability and on cocaine-induced, reward-related behaviors. Selective ablation of Girk2 in DA neurons did not alter the baseline excitability of VTA DA neurons but significantly reduced the magnitude of D2R-dependent inhibitory somatodendritic currents and blunted the impact of D2R activation on spontaneous activity and neuronal excitability. Mice lacking GIRK channels in DA neurons exhibited increased locomotor activation in response to acute cocaine administration and an altered locomotor sensitization profile, as well as increased responding for and intake of cocaine in an intravenous self-administration test. These mice, however, showed unaltered cocaine-induced conditioned place preference. Collectively, our data suggest that feedback inhibition to VTA DA neurons, mediated by GIRK channel activation, tempers the locomotor stimulatory effect of cocaine while also modulating the reinforcing effect of cocaine in an operant-based self-administration task.
authors.affiliation: Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Nora M
authors.initials: NM
authors.lastname: McCall
authors.affiliation: Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Lydia
authors.initials: L
authors.lastname: Kotecki
authors.affiliation: Department of Physiology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors.forename: Sergio
authors.initials: S
authors.lastname: Dominguez-Lopez
authors.affiliation: Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Ezequiel
authors.initials: E
authors.lastname: Marron Fernandez de Velasco
authors.affiliation: Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Carlblom
authors.affiliation: Department of Physiology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.|Feik School of Pharmacy, University of the Incarnate Word, San Antonio, TX, USA.
authors.forename: Amanda L
authors.initials: AL
authors.lastname: Sharpe
authors.affiliation: Department of Physiology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Beckstead
authors.affiliation: Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Kevin
authors.identifier: 0000-0002-5179-9540
authors.initials: K
authors.lastname: Wickman
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D003042:Cocaine / Q000494:pharmacology*; D059290:Dopaminergic Neurons / Q000187:drug effects / Q000378:metabolism*; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D007858:Learning / Q000187:drug effects*; D051379:Mice; D008822:Mice, Transgenic; D017448:Receptors, Dopamine D2 / Q000187:drug effects / Q000378:metabolism*; D012201:Reward; D017557:Ventral Tegmental Area / Q000187:drug effects / Q000378:metabolism*
chemical_list: C000600618:DRD2 protein, mouse; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; C497069:Kcnj6 protein, mouse; D017448:Receptors, Dopamine D2; D003042:Cocaine