Psychomotor stimulant drugs such as amphetamine produce multiple effects. Notable among them is their ability to activate brain dopamine (DA) neurotransmission, increase locomotor activity and support self-administration in humans and laboratory animals. When repeatedly administered, their ability to produce these effects becomes enhanced so that re-exposure to the drug, weeks to months later, produces greater DA activation, locomotion, and work-output aimed at obtaining the drug. These findings support the proposal that sensitization of the appetitive effects of amphetamine and other psychostimulants promotes the pursuit and self-administration of these drugs and may underlie the transition from casual drug use to compulsive drug taking and abuse. A number of long-lasting neuroadaptations have been identified in forebrain regions like the nucleus accumbens (NAcc) that provide neuronal correlates for the expression of behavioral sensitization by amphetamine. Several lines of converging evidence now indicate a coordinated interaction between DA and glutamate in the expression of amphetamine sensitization, one in which the regulation of AMPA receptors is essential, and that is dependent on pre- and postsynaptic PKC signaling in the NAcc. This proposal builds on new data from the laboratory showing that DA can regulate AMPA receptor trafficking and function to enable the expression of behavioral sensitization. It also incorporates recently published findings showing new mechanisms by which PKC can directly and indirectly regulate AMPA receptor insertion and function. Together, these findings support the hypothesis that NAcc AMPA receptors activate medium spiny neurons and the ensuing motivated behavior the animal displays while Gq-coupled DA receptors enable the expression of sensitization by initiating PKC-mediated signaling to regulate AMPA receptor trafficking and function. To begin testing this hypothesis, the experiments outlined in this proposal will use a model of enhanced amphetamine self-administration and reinstatement to determine the role played by different PKC substrates in the NAcc in the expression of these sensitized behaviors. The proposed experiments exploit a multidisciplinary approach, using behavioral, biochemical, pharmacological, and viral-mediated gene transfer techniques.
In Aims 1 and 2, viral-mediated gene transfer will be used to determine the contribution of PKC phosphorylation of GluR1 and neurogranin specifically in NAcc neurons to the expression of sensitization.
In Aim 3, pharmacological inhibition of PKC will be used to assess its ability to enable the expression of amphetamine sensitization by regulating presynaptic DA overflow. By deciphering the neuroadaptations that underlie the expression of sensitization, we will increase our understanding of the mechanisms underlying the enhanced pursuit and self- administration of psychostimulant drugs and inform the development of therapeutic strategies aimed at reversing these maladaptive behaviors.

Public Health Relevance

Drug addiction, a disease associated with long-lasting changes in brain, is uniquely costly to society and affects the health, productivity, and well-bein of individuals in various age groups and demographics. The goal of the proposed experiments is to characterize these long-lived neuroadaptations that underlie compulsive drug use. Understanding these changes will help inform the development of novel therapeutic and pharmacological treatments for the disease.

National Institute of Health (NIH)
National Institute on Drug Abuse (NIDA)
Research Project (R01)
Project #
Application #
Study Section
Neurobiology of Motivated Behavior Study Section (NMB)
Program Officer
Pilotte, Nancy S
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Chicago
Schools of Medicine
United States
Zip Code
Singer, Bryan F; Neugebauer, Nichole M; Forneris, Justin et al. (2014) Locomotor conditioning by amphetamine requires cyclin-dependent kinase 5 signaling in the nucleus accumbens. Neuropharmacology 85:243-52
Singer, B F; Forneris, J; Vezina, P (2014) Inhibiting cyclin-dependent kinase 5 in the nucleus accumbens enhances the expression of amphetamine-induced locomotor conditioning. Behav Brain Res 275:96-100
Neugebauer, Nichole M; Cortright, James J; Sampedro, Georgia R et al. (2014) Exposure to nicotine enhances its subsequent self-administration: contribution of nicotine-associated contextual stimuli. Behav Brain Res 260:155-61
Leyton, Marco; Vezina, Paul (2014) Dopamine ups and downs in vulnerability to addictions: a neurodevelopmental model. Trends Pharmacol Sci 35:268-76
Coccaro, Emil F; Lee, Royce; Vezina, Paul (2013) Cerebrospinal fluid glutamate concentration correlates with impulsive aggression in human subjects. J Psychiatr Res 47:1247-53
Loweth, Jessica A; Li, Dongdong; Cortright, James J et al. (2013) Persistent reversal of enhanced amphetamine intake by transient CaMKII inhibition. J Neurosci 33:1411-6
Singer, B F; Scott-Railton, J; Vezina, P (2012) Unpredictable saccharin reinforcement enhances locomotor responding to amphetamine. Behav Brain Res 226:340-4
Suto, Nobuyoshi; Wise, Roy A; Vezina, Paul (2011) Dorsal as well as ventral striatal lesions affect levels of intravenous cocaine and morphine self-administration in rats. Neurosci Lett 493:29-32
Li, Dongdong; Herrera, Stacy; Bubula, Nancy et al. (2011) Casein kinase 1 enables nucleus accumbens amphetamine-induced locomotion by regulating AMPA receptor phosphorylation. J Neurochem 118:237-47
Cortright, James J; Lorrain, Daniel S; Beeler, Jeff A et al. (2011) Previous exposure to delta9-tetrahydrocannibinol enhances locomotor responding to but not self-administration of amphetamine. J Pharmacol Exp Ther 337:724-33

Showing the most recent 10 out of 35 publications