Potentiation of morphine hyperthermia in cats by pimozide and fluoxetine hydrochloride

Edward D. French, S. A. Vasquez, Robert George

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Administration of morphine sulfate (1-4 mg/kg i.v.) to cats produces changes in body temperature, with hyperthermia appearing with larger doses. Since the central neurotransmitters dopamine and serotonin have been implicated in thermoregulation, studies were done to determine whether morphine's action could be mediated via these transmitters. Temperature responses were measured in freely moving cats by means of rectal thermometer probes. Either pimozide, 0.5 mg/kg i.p., a specific DA receptor blocker, or fluoxetine HCl, 10 mg/kg i.p., a specific inhibitor of 5-HT uptake, was administered 2-3 h prior to morphine injection. Temperatures were monitored for 3.5 h after morphine administration. Both agents were found to enhance the hyperthermic response to morphine with the maximum morphine effect occurring in most cases by 2h. The results indicate that a balance in the ratio of 5-HT : DA may be involved in cat thermoregulation and that the hyperthermic responses in the cat to morphine may be affected by shifting this 5-HT : DA ratio.

Original languageEnglish (US)
Pages (from-to)351-356
Number of pages6
JournalEuropean Journal of Pharmacology
Issue number4
StatePublished - Apr 15 1978
Externally publishedYes


  • Cats
  • Dopamine
  • Fluoxetine
  • Morphine
  • Pimozide
  • Serotonin
  • Thermoregulation

ASJC Scopus subject areas

  • Pharmacology


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