title: Cdk5 modulates cocaine reward, motivation, and striatal neuron excitability.
abstract: Cyclin-dependent kinase 5 (Cdk5) regulates dopamine neurotransmission and has been suggested to serve as a homeostatic target of chronic psychostimulant exposure. To study the role of Cdk5 in the modulation of the cellular and behavioral effects of psychoactive drugs of abuse, we developed Cre/loxP conditional knock-out systems that allow temporal and spatial control of Cdk5 expression in the adult brain. Here, we report the generation of Cdk5 conditional knock-out (cKO) mice using the alphaCaMKII promoter-driven Cre transgenic line (CaMKII-Cre). In this model system, loss of Cdk5 in the adult forebrain increased the psychomotor-activating effects of cocaine. Additionally, these CaMKII-Cre Cdk5 cKO mice show enhanced incentive motivation for food as assessed by instrumental responding on a progressive ratio schedule of reinforcement. Behavioral changes were accompanied by increased excitability of medium spiny neurons in the nucleus accumbens (NAc) in Cdk5 cKO mice. To study NAc-specific effects of Cdk5, another model system was used in which recombinant adeno-associated viruses expressing Cre recombinase caused restricted loss of Cdk5 in NAc neurons. Targeted knock-out of Cdk5 in the NAc facilitated cocaine-induced locomotor sensitization and conditioned place preference for cocaine. These results suggest that Cdk5 acts as a negative regulator of neuronal excitability in the NAc and that Cdk5 may govern the behavioral effects of cocaine and motivation for reinforcement.
authors.affiliation: Department of Psychiatry, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Benavides
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Quinn
authors.forename: Ping
authors.initials: P
authors.lastname: Zhong
authors.forename: Ammar H
authors.initials: AH
authors.lastname: Hawasli
authors.forename: Ralph J
authors.initials: RJ
authors.lastname: DiLeone
authors.forename: Janice W
authors.initials: JW
authors.lastname: Kansy
authors.forename: Peter
authors.initials: P
authors.lastname: Olausson
authors.forename: Zhen
authors.initials: Z
authors.lastname: Yan
authors.forename: Jane R
authors.initials: JR
authors.lastname: Taylor
authors.forename: James A
authors.initials: JA
authors.lastname: Bibb
mesh_terms: D000818:Animals; D003042:Cocaine / Q000494:pharmacology*; D003342:Corpus Striatum / Q000187:drug effects / Q000201:enzymology*; D051360:Cyclin-Dependent Kinase 5 / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009042:Motivation; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000201:enzymology*; D012201:Reward
chemical_list: D051360:Cyclin-Dependent Kinase 5; D003042:Cocaine