Placebo reins in pain in brain.
The scientists administered an intravenous salt solution, which they described to volunteers as a pain reliever, to seven men who also received a jaw injection that caused a moderately painful muscle spasm for about 20 minutes. Another seven men received the jaw injection but not the placebo.
In brain scans of the placebo group only, positron-emission tomography and molecular-imaging techniques revealed pronounced activity at brain-cell receptors for chemical messengers known as endorphins. Prior studies had linked endorphins to pain relief.
Men who reported the greatest relief from the placebo injections exhibited the most-intense responses at endorphin receptors in the brain, Zubieta's group reports.
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|Article Type:||Brief Article|
|Date:||Sep 3, 2005|
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