Evidence for opioid and non-opioid forms of stress-induced analgesia in the snail, Cepaea nemoralis

Brain Res. 1987 Apr 28;410(1):111-5. doi: 10.1016/s0006-8993(87)80029-x.


Exposure to either cold or warm stress increased the thermal nociceptive thresholds of the terrestrial snail, Cepaea nemoralis. The warm stress-induced 'analgesia' was blocked by the prototypic opiate antagonist, naloxone, and the delta-opiate antagonist, ICI 154,129, and was suppressed by a 24-h pretreatment with the irreversible opiate antagonist, beta-funaltrexamine (B-FNA). In contrast, cold stress-induced analgesia was unaffected by either naloxone, ICI 154,129 or B-FNA. These results indicate that this mollusc displays both opioid and non-opioid forms of stress-induced analgesia in a manner analogous to that reported for mammals. These findings suggest an early evolutionary development and phylogenetic continuity of opioid and non-opioid mediated stress responses to aversive environmental stimuli.

Publication types

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

MeSH terms

  • Animals
  • Cold Temperature / adverse effects
  • Endorphins / physiology*
  • Enkephalin, Leucine / analogs & derivatives
  • Hot Temperature / adverse effects
  • Naloxone
  • Naltrexone / analogs & derivatives
  • Pain / physiopathology*
  • Reaction Time / physiology
  • Snails / physiology*
  • Stress, Physiological / physiopathology*


  • Endorphins
  • Naloxone
  • Enkephalin, Leucine
  • Naltrexone
  • beta-funaltrexamine
  • ICI 154129