Opioid modulation of amphetamine-stimulated dopamine release and concentration in rat striatal slices

Malak G. Kolta, Michael T. Bardo

Research output: Contribution to journalArticlepeer-review


The effects of morphine and naltrexone on amphetamine-stimulated release and total concentration of dopamine (DA) from rat striatal slices in vitro were examined in this study. Adult male Sprague-Dawley rats were sacrificed and the striata were dissected, sliced, and then incubated in buffer solution of 37°C with amphetamine in the presence or absence of various concentrations of morphine, naltrexone (or both), or the dihydroxyphenylalanine (DOPA) decarboxylase inhibitor (NSD-1015). The concentrations of DOPA, DA, and dihydroxyphenylacetic acid (DOPAC) in the tissue slices and buffer media were measured by HPLC/EC. Amphetamine enhanced DA release and also increased total DA concentration. However, neither morphine nor naltrexone alone altered DA concentration in the media or tissue slices relative to control (no drug added). Moreover, neither morphine nor naltrexone at 1, 10, or 100 μM altered amphetamine-stimulated DA release. However, morphine (1 or 10 μM) inhibited the amphetamine-stimulated increase in total concentration of DA. This effect of morphine was blocked by naltrexone. NSD-1015 alone or in combination with morphine did not alter amphetamine-stimulated DA release, but significantly reduced DA concentration in striatal slices. NSD-1015 alone also increased DOPA accumulation in both media and tissue slices, and this effect was inhibited by the addition of morphine. These results indicate that morphine inhibits the amphetamine-stimulated increase in total DA content, but not the amphetamine-stimulated release of DA.

Original languageEnglish
Pages (from-to)819-825
Number of pages7
JournalPharmacology Biochemistry and Behavior
Issue number4
StatePublished - Dec 1993

Bibliographical note

Funding Information:
This study was supported, in part, by a "Research Centers in Minority Institutions" award, RR-GM 03020, from the Division of Research Resources, National Institutes of Health, and by a USPHS grant (DA05312). The authors would like to thank Ms. Joyce Gaymon Horne for preparing this manuscript and Ms. O. Sylvia Lamar for editorial assistance.


  • Amphetamine
  • Endogenous dopamine
  • In vitro
  • Opioid
  • Rat
  • Striatum

ASJC Scopus subject areas

  • Biochemistry
  • Toxicology
  • Pharmacology
  • Clinical Biochemistry
  • Biological Psychiatry
  • Behavioral Neuroscience


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