Prevention of cocaine-induced hyperactivity by a naloxone isomer with no opiate antagonist activity

Neurochem Res. 1996 Jun;21(6):691-3. doi: 10.1007/BF02527726.


Dextro-naloxone [(+)-naloxone], an isomer with almost no opiate antagonist activity and no effect on spontaneous locomotor activity, can reduce cocaine-induced hyperactivity in mice. The classical opiate antagonist, levo-naloxone [(-)-naloxone], is known to counteract the excitatory motor effects of amphetamine and cocaine, but it has been tacitly assumed that this action of levo-naloxone is dependent on its ability to antagonize endogenous opioids. Our finding that a naloxone isomer with little or no opioid antagonist activity is also able to inhibit the cocaine effect on spontaneous motility, calls for a reconsideration of this assumption.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Cocaine / antagonists & inhibitors*
  • Hyperkinesis / chemically induced
  • Hyperkinesis / prevention & control*
  • Male
  • Mice
  • Motor Activity / drug effects
  • Naloxone / pharmacology*
  • Narcotic Antagonists / pharmacology
  • Stereoisomerism


  • Narcotic Antagonists
  • Naloxone
  • Cocaine