Neurogastroenterology and motility : the official journal of the European Gastrointestinal Motility Society
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Neurogastroenterol. Motil. · Oct 2014
ReviewSite and mechanism of morphine tolerance in the gastrointestinal tract.
Opioid-induced constipation is a major clinical problem. The effects of morphine, and other narcotics, on the gastrointestinal tract persist over long-term use thus limiting the clinical benefit of these excellent pain relievers. The effects of opioids in the gut, including morphine, are largely mediated by the μ-opioid receptors at the soma and nerve terminals of enteric neurons. ⋯ Here, we review the mechanisms by which tolerance develops in the small but not the large intestine. The regional differences lie in the signaling and regulation of the μ-opioid receptor in the various segments of the gastrointestinal tract. The differential role of β-arrestin2 in tolerance development between central and enteric neurons defines the potential for therapeutic approaches in developing ligands with analgesic properties and minimal constipating effects.
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Neurogastroenterol. Motil. · Oct 2014
ReviewEmerging treatments in neurogastroenterology: a multidisciplinary working group consensus statement on opioid-induced constipation.
Opioids are effective for acute and chronic pain conditions, but their use is associated with often difficult-to-manage constipation and other gastrointestinal (GI) effects due to effects on peripheral μ-opioid receptors in the gut. The mechanism of opioid-induced constipation (OIC) differs from that of functional constipation (FC), and OIC may not respond as well to most first-line treatments for FC. The impact of OIC on quality of life (QoL) induces some patients to decrease or stop their opioid therapy to relieve or avoid constipation. ⋯ At a roundtable meeting on OIC, a working group developed a consensus definition for OIC diagnosis across disciplines and reviewed current OIC treatments and the potential of treatments in development. By consensus, OIC is defined as follows: 'A change when initiating opioid therapy from baseline bowel habits that is characterized by any of the following: reduced bowel movement frequency, development or worsening of straining to pass bowel movements, a sense of incomplete rectal evacuation, or harder stool consistency'. The working group noted the prior validation of a patient response outcome and end point for clinical trials and recommended future efforts to create treatment guidelines and QoL measures specific for OIC. Details from the working group's discussion and consensus recommendations for patient care and research are presented in this article.
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Neurogastroenterol. Motil. · Sep 2014
ReviewA systematic review of sacral nerve stimulation mechanisms in the treatment of fecal incontinence and constipation.
Sacral nerve stimulation (SNS) is now well established as a treatment for fecal incontinence (FI) resistant to conservative measures and may also have utility in the management of chronic constipation; however, mechanism of action is not fully understood. End organ effects of SNS have been studied in both clinical and experimental settings, but interpretation is difficult due to the multitude of techniques used and heterogeneity of reported findings. The aim of this study was to systematically review available evidence on the mechanisms of SNS in the treatment of FI and constipation. ⋯ The initial hypothesis that the mechanism of SNS was primarily peripheral motor neurostimulation is not supported by the majority of recent studies. Due to the large body of evidence demonstrating effects outside of the anorectum, it appears likely that the influence of SNS on anorectal function occurs at a pelvic afferent or central level.
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Neurogastroenterol. Motil. · Sep 2014
ReviewA systematic review of sacral nerve stimulation mechanisms in the treatment of fecal incontinence and constipation.
Sacral nerve stimulation (SNS) is now well established as a treatment for fecal incontinence (FI) resistant to conservative measures and may also have utility in the management of chronic constipation; however, mechanism of action is not fully understood. End organ effects of SNS have been studied in both clinical and experimental settings, but interpretation is difficult due to the multitude of techniques used and heterogeneity of reported findings. The aim of this study was to systematically review available evidence on the mechanisms of SNS in the treatment of FI and constipation. ⋯ The initial hypothesis that the mechanism of SNS was primarily peripheral motor neurostimulation is not supported by the majority of recent studies. Due to the large body of evidence demonstrating effects outside of the anorectum, it appears likely that the influence of SNS on anorectal function occurs at a pelvic afferent or central level.
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Neurogastroenterol. Motil. · Nov 2013
ReviewNon-celiac gluten sensitivity: clinical relevance and recommendations for future research.
There has been increasing interest in the entity of Non-Celiac Gluten Sensitivity (NCGS) in recent years; however, it still remains a controversial topic and its pathogenesis is not well understood. Celiac Disease, in contrast, is a well-studied condition that has become increasingly recognized as a prevalent condition arising from a heightened immunological response to gluten. Wheat allergy is an IgE-mediated condition capable of causing a variety of gastrointestinal symptoms. However, the number of patients who have neither celiac disease nor wheat allergy, but appear to derive benefit from a gluten-free diet, is also increasing substantially. The use of the term NCGS as a way of describing this condition has become increasingly prevalent in recent years. ⋯ In this review, we will focus on gastrointestinal manifestations of NCGS and discuss the evidence for the condition and its putative pathogenesis. We will discuss areas of controversy and areas for potential future research.