Individual differences in amphetamine self-administration: The role of the central nucleus of the amygdala

Mary E. Cain, Emily D. Denehy, Michael T. Bardo

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36 Scopus citations


Rats categorized as high responder (HR), based on their activity in an inescapable novel environment, self-administer more amphetamine than low responder (LR) rats. The current study examined if the central nucleus of the amygdala (ACe) contributes to the elevated response for amphetamine in HR rats. Male Sprague-Dawley rats were classified as HR and LR rats based on their activity in inescapable novelty and novelty place preference, and then were trained to self-administer amphetamine (0.1 mg/kg/infusion). Once stable responding was achieved, rats received microinfusions of the GABAA agonist muscimol (0.5 μg/0.5 μl) or phosphate-buffered saline into the ACe immediately before self-administration of amphetamine (0.1, 0.03, 0.01, or 0.001 mg/kg/infusion) or saline. An additional group of rats was trained to lever press for sucrose rather than amphetamine. Based on the inescapable novelty test, HR rats self-administered more amphetamine than LR rats at the 0.03 and 0.01 mg/kg/infusion unit doses; there were no significant individual differences in amphetamine self-administration based on the novelty place preference test. Inactivation of the ACe with muscimol decreased self-administration at the 0.03 and 0.01 mg/kg/infusion unit doses in HR rats, but had no effect on LR rats. ACe inactivation had no reliable effect on inactive lever responding and appeared to be region specific based on anatomical controls. In addition, while inactivation of the ACe decreased responding for sucrose, inactivation did not differentially affect HR and LR rats. These results suggest that the ACe contributes to the elevated rate of amphetamine self-administration in HR rats.

Original languageEnglish
Pages (from-to)1149-1161
Number of pages13
Issue number5
StatePublished - Apr 2008

Bibliographical note

Funding Information:
This research was funded by USPHS grant P50 DA05312. MEC supported by USPHS Grant F32 DA16013. We thank Justin Dixon, Bill Dotson, Laura Fenton, Nate Gilbertson, and Nichole Neugebauer for their assistance with this project.

Funding Information:
The authors declare that this work was funded by NIH grants DA05312 and DA16013. We declare that, except for the income received from our primary employers, no financial support or compensation has been received from any individual or corporate entity over the past 3 years for research or professional service and there are no personal financial holdings that could be perceived as constituting a potential conflict of interests.


  • Amphetamine
  • Central nucleus of the amygdala
  • Individual differences
  • Inescapable novelty
  • Muscimol
  • Self-administration

ASJC Scopus subject areas

  • Pharmacology
  • Psychiatry and Mental health


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