Brain, behavior, and immunity
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Brain Behav. Immun. · Mar 2011
ReviewAbdominal pain in Irritable Bowel Syndrome: a review of putative psychological, neural and neuro-immune mechanisms.
Chronic abdominal pain is a common symptom of great clinical significance in several areas of medicine. In many cases no organic cause can be established resulting in the classification as functional gastrointestinal disorder. Irritable Bowel Syndrome (IBS) is the most common of these conditions and is considered an important public health problem because it can be disabling and constitutes a major social and economic burden given the lack of effective treatments. ⋯ At the same time, there is growing evidence linking peripheral and mucosal immune changes and abdominal pain in IBS, supporting disturbed peripheral pain signalling. Findings in post-infectious IBS emphasize the interaction between centrally-mediated psychosocial risk factors and local inflammation in predicting long-term IBS symptoms. Investigating afferent immune-to-brain communication in visceral hyperalgesia as a component of the sickness response constitutes a promising future research goal.
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Morphine and related compounds are the first line of therapy in the treatment of moderate to severe pain. Over time, individuals taking opioids can develop an increasing sensitivity to noxious stimuli, even evolving into a painful response to previously non-noxious stimuli (opioid-induced hyperalgesia; OIH). The mechanism underlying OIH is not well understood although complex intracellular neural mechanisms, including opioid receptor desensitization and down-regulation, are believed to be major mechanisms underlying OIH. ⋯ We further determined that there is pronounced CXCR4 expression in satellite glial cells and following morphine treatment, increased functional CXCR4 expression in sensory neurons of the DRG. Moreover, intraperitoneal administration of the specific CXCR4 antagonist, AMD3100, completely reversed OIH in the rat. Taken together; the data suggest that opioid-induced SDF1/CXCR4 signaling is central to the development of long lasting OIH and that receptor antagonists represent a promising novel approach to the management of the side effects associated with the use of opioids for chronic pain management.