Levorphanol and swim stress-induced analgesia in selectively bred mice: evidence for genetic commonalities

Brain Res. 1993 Apr 16;608(2):353-7. doi: 10.1016/0006-8993(93)91479-c.


Two independent selective breeding programs have developed divergent lines of mice expressing either high and low swim stress-induced analgesia (HA/LA lines; Jastrzebiec, Poland) or high and low levorphanol analgesia (HAR/LAR lines; Portland, OR). In the present study, mice from both programs were tested for both levorphanol analgesia (2 mg/kg) and an opioid-mediated swim stress-induced analgesia (3 min swimming in 32 degrees C water) in the hot-plate test. Mice selected for high and low levorphanol analgesia displayed high and low swim stress-induced analgesia, respectively; mice selected for high and low swim stress-induced analgesia displayed high and low levorphanol analgesia, respectively. This pattern of correlated responses suggests a high degree of common genetic determination in opiate and swim stress-induced analgesia. These findings also suggest that individual differences in analgesic responsiveness to opiate drugs result from genetically determined individual differences in endogenous pain inhibitory mechanisms.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Analgesia*
  • Animals
  • Female
  • Hot Temperature
  • Individuality
  • Levorphanol / pharmacology*
  • Male
  • Mice
  • Mice, Inbred Strains
  • Pain Threshold / drug effects
  • Species Specificity
  • Stress, Psychological / genetics*
  • Stress, Psychological / psychology
  • Swimming


  • Levorphanol