Articles: opioid.
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Am. J. Physiol. Gastrointest. Liver Physiol. · Aug 2016
Distribution and trafficking of the μ-opioid receptor in enteric neurons of the guinea pig.
The μ-opioid receptor (MOR) is a major regulator of gastrointestinal motility and secretion and mediates opiate-induced bowel dysfunction. Although MOR is of physiological and therapeutic importance to gut function, the cellular and subcellular distribution and regulation of MOR within the enteric nervous system are largely undefined. Herein, we defined the neurochemical coding of MOR-expressing neurons in the guinea pig gut and examined the effects of opioids on MOR trafficking and regulation. ⋯ After stimulation with DAMGO and morphiceptin, MOR recycled, whereas MOR was retained within endosomes following loperamide treatment. Herkinorin or the δ-opioid receptor agonist [d-Ala(2), d-Leu(5)]enkephalin (DADLE) did not evoke MOR endocytosis. In summary, we have identified the neurochemical coding of MOR-positive enteric neurons and have demonstrated differential trafficking of MOR in these neurons in response to established and putative MOR agonists.
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In the past 2 decades, opioids have been used increasingly for the treatment of persistent pain, and doses have tended to creep up. As basic science elucidates mechanisms of pain and analgesia, the cross talk between central pain and opioid actions becomes clearer. ⋯ Newly revealed basic mechanisms suggest possible avenues for drug development and new drug therapies that could alter pain sensitization through endogenous and exogenous opioid mechanisms. Recent changes in practice such as the introduction of titration-to-effect for opioids have resulted in higher doses used in the clinic setting than ever seen previously. New basic science knowledge hints that these newer dosing practices may need to be reexamined. When pain worsens in a patient taking opioids, can we be assured that this is not because of the opioids, and can we alter this negative effect of opioids through different dosing strategies or new drug intervention?
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J Subst Abuse Treat · Jul 2016
Patients' Beliefs About Medications are Associated with Stated Preference for Methadone, Buprenorphine, Naltrexone, or no Medication-Assisted Therapy Following Inpatient Opioid Detoxification.
Subsequent to initial opioid detoxification, people with opioid use disorder are typically advised to engage in follow-up treatment to prevent relapse. Medication-assisted treatments (MATs) - i.e., the opioid agonist methadone (MMT) or partial agonist/antagonist, buprenorphine/naltrexone (BUP) -- are the maintenance treatment options with the best research support for positive outcomes. A third MAT, injectable extended-release naltrexone (XR-NTX), was approved by the FDA for opioid dependence in 2010 and shows promise. ⋯ Perceived structural barriers were not related to stated preferences, except that people who preferred BUP were more likely to endorse barriers to MMT than any of the other 3 groups. Notably, a relatively high proportion (32%) of participants were most interested in XR-NTX despite a lack of prior experience with this medication. These results suggest that efforts to increase MAT enrollment following detoxification might benefit from including patient beliefs as one set of factors to assess and target for change.
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Understanding opioid prescribing trends requires differentiating clinically distinct short- and long-term receipt patterns. ⋯ The proportion of new opioid recipients who initiated long-term opioid therapy declined between 2004 and 2011.