Reduction of conditioned pain modulation in humans by naltrexone: an exploratory study of the effects of pain catastrophizing.

Abstract

The current study tested the hypothesis that conditioned pain modulation is mediated by the release of endogenous opioids with a placebo-controlled (sugar pill) study of naltrexone (50 mg) in 33 healthy volunteers over two counter-balanced sessions. Pain modulation consisted of rating of heat pain (palm) during concurrent cold water immersion (foot). Compared to baseline heat pain ratings, concurrent foot immersion lowered pain intensity ratings, which suggests an inhibitory effect, was reduced with naltrexone, suggesting at least partial dependence of inhibition on endogenous opioids. An exploratory analysis revealed that individual differences in catastrophizing moderated the effects of naltrexone; endogenous opioid blockade abolished modulation in subjects lower in catastrophizing while modulation was unaffected by naltrexone among high catastrophizers. The results suggest a role of endogenous opioids in endogenous analgesia, but hint that multiple systems might contribute to conditioned pain modulation, and that these systems might be differentially activated as a function of individual differences in responses to pain.

• Authors: Christopher D King, Burel Goodin, Lindsay L Kindler, Robert M Caudle, Robert R Edwards, Nikolaus Gravenstein, Joseph L Riley 3rd, Roger B Fillingim
• Journal: Journal of behavioral medicine (J Behav Med) Vol. 36 Issue 3 Pg. 315-27 (Jun 2013) ISSN: 1573-3521 [Electronic] United States
• PMID: 22534819 (Publication Type: Journal Article, Randomized Controlled Trial, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• Narcotic Antagonists
• Opioid Peptides
• Naltrexone

Topics

• Adult
• Catastrophization (physiopathology, psychology)
• Conditioning, Classical (drug effects, physiology)
• Cross-Over Studies
• Diffuse Noxious Inhibitory Control (drug effects, physiology)
• Double-Blind Method
• Female
• Humans
• Individuality
• Male
• Naltrexone (pharmacology)
• Narcotic Antagonists (pharmacology)
• Opioid Peptides (physiology)
• Pain (physiopathology, psychology)
• Pain Threshold (drug effects, physiology)
• Young Adult