Neurobiology

Even more pain in opioid treatment

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Science  08 Jul 2016:
Vol. 353, Issue 6295, pp. 134
DOI: 10.1126/science.353.6295.134-c

Amid heightened concern about the addictive properties of opiates used to manage pain, new results from Grace et al. reveal that morphine can actually promote chronic pain. Rats with nerve damage treated for 5 days with morphine showed a sensitization to pain that persisted for months after opioid treatment was stopped. Neuronal opioid receptors did not contribute to this effect. Rather, opioids caused the increased pain by heightening inflammatory signaling in macrophage-like cells called microglia that reside in the spinal cord and brain. On the positive side, specific targeting of the inflammatory signaling in microglia may block the long-term pain-inducing effects of opioids, while still allowing their short-term analgesic effects.

Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1602070113 (2016).

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