Components of the opioid withdrawal syndrome in mice are thermoregulatory responses

J. K. Belknap

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


C57BL/6J mice were rendered physically dependent on morphine by giving them ad lib access to a drinking fluid containing 0.2% saccharin and morphine for 14 days at 20-22°C. Core body temperatures were monitored by radio telemetry, which obviated the need for restraint, handling, or otherwise disturbing the animals. Consistent hyperthermia was present throughout the morphine intoxication phase, followed by hypothermia after the withdrawal syndrome had been precipitated by naloxone challenge (2.0 mg/kg, IP) at 22.5°C. The hypothermia could be blocked by exposing the animals to a 34.5°C ambient temperature, which also prevented the occurrence of tremor and "wet dog shakes." In contrast, the other withdrawal signs monitored were not significantly affected. In a second experiment, mice were given the same morphine-saccharin drinking fluid as before, except that a choice was provided between two interconnected home cages (23°C vs. 35°C) throughout the experiment. A marked preference for the 35°C cage was seen during intoxication, which served to enhance the hyperthermia due to morphine. Following withdrawal, when hypothermia is evident, the preference for the 35°C cage declined to control levels. These results suggest that hypothermia is both a consequence and a contributor to the opioid withdrawal syndrome.

Original languageEnglish (US)
Pages (from-to)241-245
Number of pages5
JournalPharmacology, Biochemistry and Behavior
Issue number2
StatePublished - Oct 1989


  • C57BL/6J mice
  • Hypothermia
  • Morphine
  • Opioids
  • Physical dependence Body temperature by radio telemetry
  • Thermoregulation
  • Withdrawal syndrome

ASJC Scopus subject areas

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


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