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A real pain in the (rat) guts

By Timothy Cocks Science and the world 30 Jan 2014

Using Morphine After Abdominal Surgery May Prolong Pain

Using morphine to fight the pain associated with abdominal surgery may paradoxically prolong a patient’s suffering, doubling or even tripling the amount of time it takes to recover from the surgical pain, according to researchers at the University of Colorado Boulder.

The research team from CU-Boulder’s Department of Psychology and Neuroscience — led by Peter Grace, a postdoctoral research fellow, together with Erika Galer, a professional research assistant — was able to identify the mechanism that caused the prolonged pain. The scientists found that both the morphine and the surgery itself excited glial cells in the nervous system, causing them to send out additional pain signals to the surrounding nerves.

The research findings, which involved a study using rats, are being presented today at the annual meeting of the Society for Neuroscience in San Diego.

“After abdominal surgery — even without using any drugs to treat the pain — the glial cells would be activated and they would contribute to the postoperative pain,” Grace said. “What we’re saying is, if you give them morphine, we also know that contributes to the pain. If you’re putting both of those on top of each other, you’re going to have a prolonged period of pain. (Bold added)

Clearly more than just glue

– Tim Cocks

Join the “Other Brain” revolution, embrace glia and the neuroimmune brain as a target for treatment – noigroup courses 2014


  1. davenolan22

    Hi Tim,

    The implications for this study, if true, reliable and repeated, are pretty huge.

    My knowledge is not what is should be in this area, but do all opioids have similar effect on glial?

    1. timcocks0noi

      Hi Dave, thanks for stopping by and taking the time to comment.

      From my reading of the literature, I understand that the link between opioids and glial activation is quite well established.

      Linda Watkins and Erin Milligan are two heavy hitters in this area, as is Adelaide’s Mark Hutchinson (as Aussies we love to claim people).

      There is a great mini review article “Opioid-Induced Glial Activation: Mechanisms of Activation and Implications for Opioid Analgesia, Dependence, and Reward” from 2007 from Hutchinson, Watkins and others that is freely available –

      They address the issue of the effect of differing opioids and state

      “All studies published to date have investigated glial activation by morphine, the prototypical opioid. However, for modulation of opioid analgesic efficacy by glial activation to be globally relevant, this phenomenon should be generalizable to other clinically relevant opioids. This is, in fact, the case as glial activation in response to another 4,5-epoxymorphinan, oxycodone[50], and the structurally disparate
      synthetic 3,3-diphenylpropylamine opioid, methadone[49], each compromise the resultant analgesia.” (Hutchinson et al 2007, pp 106 )

      It is important to note that the study mentioned in the original post was carried out on rats, which I think makes the mention of “patients” in the very first sentence somewhat misleading, however, I think its safe to say that this finding, along with the large body of literature on the subject should give prescribers another reason to stop and think about opioids (as if they needed another one!)


      Hutchinson, M.R., Bland, S.T., Johnson, K.W., Rice, K.C., Maier, S.F., and Watkins, L.R. (2007) Opioid-induced glial activation: mechanisms of activation and implications for opioid analgesia, dependence, and reward.
      The Scientific World JOURNAL 7(S2), 98–111. DOI 10.1100/tsw.2007.230.

    1. timcocks0noi

      Hey David, I know. It’s still rampant in so much of the pain science literature. Seems like such a small thing, but what a mess those two little words together have gotten us in.


  2. Hi Tim,
    The fact that NOI knows what I mean with my comment is what makes NOI unique, and noijam priceless and the only site worth following…….
    Warm Regards

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