Effects of morphine on thermal sensitivity in adult and aged rats

Academic Article


  • There are contradictory data regarding older individuals' sensitivity to pain stimulation and opioid administration. Adult (12-16 months; n = 10) and aged (27-31 months; n = 7) male F344xBN rats were tested in a thermal sensitivity procedure where the animal chooses to remain in one of two compartments with floors maintained at various temperatures ranging from hot (45°C) through neutral (30°C) to cold (15°C). Effects of morphine were determined for three temperature comparisons (ie, hot/neutral, cold/neutral, and hot/cold). Aged rats were more sensitive to cold stimulation during baseline. Morphine produced antinociception during hot thermal stimulation, but had no effect on cold stimulation. The antinociceptive (and locomotor-altering) effects of morphine were attenuated in aged rats. These data demonstrate age-related differences in baseline thermal sensitivity and responsiveness to opioids. Based on behavioral and physiological requirements of this procedure, it is suggested that thermal sensitivity may provide a relevant animal model for the assessment of pain and antinociception. © 2012 The Gerontological Society of America.
  • Authors

    Digital Object Identifier (doi)

    Author List

  • Morgan D; Mitzelfelt JD; Koerper LM; Carter CS
  • Start Page

  • 705
  • End Page

  • 713
  • Volume

  • 67 A
  • Issue

  • 7