Jan 5, 2011

Treating pain with pain: supraspinal mechanisms of endogenous analgesia elicited by heterotopic noxious conditioning stimulation

Pain
Christian SprengerChristian Büchel

Abstract

While being exposed to an intensive tonic pain stimulus at one area of the body, another phasic pain stimulus applied to a remote site is perceived as less painful. The neurophysiological basis for this "pain inhibits pain" phenomenon has been presumed to be an activation of the spino-bulbo-spinal mechanism termed "diffuse noxious inhibitory controls." However, several additional mechanisms such as an activation of the descending pain control system may contribute to this observation. Here we investigated the underlying supraspinal mechanisms of "heterotopic noxious conditioning stimulations" (HNCS), representing this specific experimental constellation. We used functional magnetic resonance imaging and behavioral recordings in combination with a modified cold-pressor task and phasic painful stimuli, and investigated the contribution of endogenous opioids to this mechanism using the opioid antagonist naloxone in a double-blind crossover design. HNCS led to marked endogenous analgesia and this effect correlated positively with the perceived intensity of the tonic painful stimulus. Furthermore, HNCS was paralleled by reduced blood oxygen level dependent (BOLD) responses in classical pain-responsive regions. Conversely, HNCS led t...Continue Reading

Mentioned in this Paper

Biochemical Pathway
Cortex Bone Disorders
Adrenal Cortex Diseases
Tetrahydrocannabinol
Entire Brainstem
Prefrontal Cortex
Structure of Posterior Gray Horn of Spinal Cord
Naloxone
Entire Medulla Oblongata
Neurons

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