Neurochemical correlates of accumbal dopamine D2 and amygdaloid 5-HT1B receptor densities on observational learning of aggression

Hideo Suzuki, Louis R. Lucas

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Social learning theory postulates that individuals learn to engage in aggressive behavior through observing an aggressive social model. Prior studies have shown that repeatedly observing aggression, also called “chronic passive exposure to aggression,” changes accumbal dopamine D2 receptor (D2R) and amygdaloid 5-HT1B receptor (5-HT1BR) densities in observers. But, the association between these outcomes remains unknown. Thus, in our study, we used a rat paradigm to comprehensively examine the linkage between aggression, D2R density in the nucleus accumbens core (AcbC) and shell (AcbSh), and 5-HT1BR density in the medial (MeA), basomedial (BMA), and basolateral (BLA) amygdala following chronic passive exposure to aggression. Male Sprague-Dawley rats (N = 72) were passively exposed to either aggression or nonaggression acutely (1 day) or chronically (23 days). When observer rats were exposed to aggression chronically, they showed increased aggressive behavior and reduced D2R density in bilateral AcbSh. On the other hand, exposure to aggression, regardless of exposure length, increased the 5-HT1BR density in bilateral BLA. Finally, low D2R in the AcbSh significantly interacted with high 5-HT1BR density in the BLA to predict high levels of aggression in observer rats. Our results advance our understanding of the neurobiological mechanisms in the observational learning of aggression, highlighting that dopamine–serotonin interaction, or AcbSh–BLA interaction, may contribute to a risk factor for aggression in observers who chronically witness aggressive interactions.

Original languageEnglish (US)
Article number15
Pages (from-to)460-474
Number of pages15
JournalCognitive, Affective and Behavioral Neuroscience
Issue number2
StatePublished - Jun 22 2015
Externally publishedYes


  • 5-HT1B receptor
  • Aggression
  • Amygdala
  • Dopamine D2 receptor
  • Nucleus accumbens
  • Observational learning

ASJC Scopus subject areas

  • Cognitive Neuroscience
  • Behavioral Neuroscience


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