Direct regulation of diurnal Drd3 expression and cocaine reward by NPAS2

Biol Psychiatry. 2015 Mar 1;77(5):425-433. doi: 10.1016/j.biopsych.2014.07.030. Epub 2014 Aug 13.


Background: Circadian gene disruptions are associated with the development of psychiatric disorders, including addiction. However, the mechanisms by which circadian genes regulate reward remain poorly understood.

Methods: We used mice with a mutation in Npas2 and adeno-associated virus-short hairpin RNA mediated knockdown of Npas2 and Clock in the nucleus accumbens (NAc). We performed conditioned place preference assays. We utilized cell sorting quantitative real-time polymerase chain reaction, and chromatin immunoprecipitation followed by deep sequencing.

Results: Npas2 mutants exhibit decreased sensitivity to cocaine reward, which is recapitulated with a knockdown of neuronal PAS domain protein 2 (NPAS2) specifically in the NAc, demonstrating the importance of NPAS2 in this region. Interestingly, reducing circadian locomotor output cycles kaput (CLOCK) (a homologue of NPAS2) in the NAc had no effect, suggesting an important distinction in NPAS2 and CLOCK function. Furthermore, we found that NPAS2 expression is restricted to Drd1 expressing neurons while CLOCK is ubiquitous. Moreover, NPAS2 and CLOCK have distinct temporal patterns of DNA binding, and we identified novel and unique binding sites for each protein. We identified the Drd3 dopamine receptor as a direct transcriptional target of NPAS2 and found that NPAS2 knockdown in the NAc disrupts its diurnal rhythm in expression. Chronic cocaine treatment likewise disrupts the normal rhythm in Npas2 and Drd3 expression in the NAc, which may underlie behavioral plasticity in response to cocaine.

Conclusions: Together, these findings identify an important role for the circadian protein, NPAS2, in the NAc in the regulation of dopamine receptor expression and drug reward.

Keywords: Circadian; Clock; Cocaine; Drd3; Npas2; Reward.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Basic Helix-Loop-Helix Transcription Factors / genetics
  • Basic Helix-Loop-Helix Transcription Factors / metabolism*
  • CLOCK Proteins / genetics
  • CLOCK Proteins / metabolism
  • Circadian Rhythm / drug effects
  • Circadian Rhythm / physiology
  • Cocaine / pharmacology*
  • Conditioning, Psychological / drug effects
  • Conditioning, Psychological / physiology
  • Dopamine Uptake Inhibitors / pharmacology*
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism*
  • Neurons / drug effects
  • Neurons / physiology
  • Nucleus Accumbens / drug effects*
  • Nucleus Accumbens / physiology
  • Receptors, Dopamine D1 / metabolism
  • Receptors, Dopamine D3 / metabolism*
  • Reward*
  • Space Perception / drug effects
  • Space Perception / physiology


  • Basic Helix-Loop-Helix Transcription Factors
  • Dopamine Uptake Inhibitors
  • Drd3 protein, mouse
  • Nerve Tissue Proteins
  • Npas2 protein, mouse
  • Receptors, Dopamine D1
  • Receptors, Dopamine D3
  • CLOCK Proteins
  • Clock protein, mouse
  • Cocaine