Gastroenterology
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Narcotic bowel syndrome (NBS) is a subset of opioid bowel dysfunctions that results from prolonged treatment with narcotics and is characterized by chronic abdominal pain. NBS is under-recognized and its molecular mechanisms are unknown. We aimed to (1) develop a rat model of NBS and (2) to investigate its peripheral and central neurobiological mechanisms. ⋯ We developed a rat model of narcotic bowel-like syndrome and showed that spinal microglia activation mediates the development of morphine-induced visceral hyperalgesia; peripheral neuroimmune activation and spinal dynorphin release represent an important mechanism in the delayed and long-lasting morphine-induced colonic hypersensitivity response to CRD.
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Several studies have examined structural brain changes associated with chronic pain syndromes, including irritable bowel syndrome (IBS), but study sample sizes have been small and heterogeneous. ⋯ Changes in density of gray matter among regions involved in cognitive/evaluative functions are specifically observed in patients with IBS, whereas changes in other areas of the brain can be explained by levels of anxiety and depression.