Exposure to novel odors induces opioid-mediated analgesia in the land snail, Cepaea nemoralis.
Land snails, Cepaea nemoralis, that were exposed for 1-30 min to a novel odor of either peppermint extract or vegetable juice concentrate displayed an increase in the latency of their nociceptive response to an aversive thermal stimulus (40 degrees C, hot-plate). This "analgesic" response, which entailed the elevation of the fully extended foot in hydrated snails, was evident directly after exposure to the novel chemostimuli and lasted for 15-30 min. This novelty-induced analgesia was blocked by the exogenous opiate antagonist naloxone. Analgesia was not observed in snails that were exposed to the same olfactory cue 4 or 24 h later, but was evident when the alternate novel odor (peppermint or vegetable juice) was presented. However, a significant analgesia was displayed by snails that were reexposed to their initial olfactory stimulus after 48-72 h. These findings indicate that exposure to a novel olfactory stimulus can activate endogenous opioid systems and induce an analgesic response in mollusks.
Kavaliers
M
M
Division of Oral Biology, Faculty of Dentistry, University of Western Ontario, London, Canada.
Tepperman
F S
FS
D000818:Animals; D001143:Arousal / Q000502:physiology*; D002628:Chemoreceptor Cells / Q000502:physiology; D009424:Nervous System Physiological Phenomena; D009619:Nociceptors / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D011957:Receptors, Opioid / Q000502:physiology*; D012903:Smell / Q000502:physiology*; D012908:Snails / Q000502:physiology*; D013239:Stereotyped Behavior / Q000502:physiology; D013697:Thermosensing / Q000502:physiology
D011957:Receptors, Opioid