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µ Opioid Receptors

Jing Huang, Sirish Kaushik Lakkaraju, Andrew Coop, Alexander D MacKerell
G-protein coupled receptors (GPCRs), including the μ-opioid receptor, interact with G-proteins and other proteins via their intracellular face as required for signal transduction. However, characterization of the structure of the intracellular face of GPCRs is complicated by the experimental methods used for structural characterization. In the present study we undertook a series of long-time molecular dynamics (MD) simulations, ranging from 1 to 5 μs, on the μ-opioid receptor in both the dimeric and monomeric states...
November 1, 2016: Journal of Physical Chemistry. B
Sebastian Schneider, Davide Provasi, Marta Filizola
Substantial attention has recently been devoted to G protein-biased agonism of the µ-opioid receptor (MOR) as an ideal new mechanism for the design of analgesics devoid of serious side effects. However, designing opioids with appropriate efficacy and bias is challenging because it requires an understanding of the ligand binding process and of the allosteric modulation of the receptor. Here, we investigated these phenomena for TRV-130, a G protein-biased MOR small-molecule agonist that has been shown to exert analgesia with less respiratory depression and constipation than morphine, and that it is currently being evaluated in human clinical trials for acute pain management...
October 25, 2016: Biochemistry
Tyler A Johnson, Laura Milan-Lobo, Tao Che, Madeline Ferwerda, Eptisam Lambo, Nicole L McIntosh, Fei Li, Li He, Nicholas Lorig-Roach, Phillip Crews, Jennifer Lynne Whistler
Opioid therapeutics are excellent analgesics, whose utility is compromised by dependence. Morphine (1) and its clinically relevant derivatives such as OxyContin® (4), Vicodin® (5) and Dilaudid® (6) are "biased" agonists at the µ opioid receptor (OR), wherein they engage G-protein signaling but poorly engage β-arrestin and the endocytic machinery. In contrast, the endorphins, met-enkephalin (14) and β-endorphin (15), endogenous peptide agonists for ORs, are more potent analgesics then 1, show reduced liability for tolerance and dependence, and engage both G-protein and β-arrestin pathways as "balanced" agonists...
October 17, 2016: ACS Chemical Neuroscience
Richard Lawson, James Ryan, Frederic King, Jo Wern Goh, Eszter Tichy, Kevin Marsh
BACKGROUND AND OBJECTIVES: Opioid-induced constipation (OIC) is the most common adverse effect reported in patients receiving opioids to manage pain. Initial treatment with laxatives provides inadequate response in some patients. Naloxegol is a peripherally acting µ-opioid receptor antagonist used to treat patients with inadequate response to laxative(s) (laxative inadequate responder [LIR]). A cost-effectiveness model was constructed from the UK payer perspective to compare oral naloxegol 25 mg with placebo in non-cancer LIR patients receiving opioids for chronic pain, and a scenario analysis of naloxegol 25 mg with rescue laxatives compared with placebo with rescue laxatives in the same patient population...
September 23, 2016: PharmacoEconomics
Gian Maria Pacifici
Morphine is an agonist of the µ and k receptors, whose activation results in analgesia. Morphine-like agonists act through the µ opioid receptors to cause pain relief, sedation, euphoria and respiratory depression. Morphine is glucuronidated and sulfated at positions 3 and 6; the plasma concentration ratios correlate positively with birth weight, which probably reflects increased liver weight with increasing birth weight. Moreover, morphine clearance correlates positively with gestational age and birth weight...
August 2016: Clinics
Loiy Elsir Ahmed Hassan, Saad S Dahham, Samah M Fadul, Muhammad Ihtisham Umar, Aman Shah Abdul Majid, Kooi Yeong Khaw, Amin Malik Shah Abdul Majid
ETHNOPHARMACOLOGICAL RELEVANCE: Tephrosia apollinea (Delile) DC (Leguminosae) has been used in folk medicine in Arabian countries to treat inflammatory disorders. The plant has been described to treat swelling, bone fracture, bronchitis, cough, earache and wounds. AIM OF THE STUDY: the current study aims to evaluate the anti-inflammatory properties of the major active phytoconstituent of T. apollinea and elucidate the mechanisms by which it inhibits inflammation in vitro and in vivo...
August 20, 2016: Journal of Ethnopharmacology
Ya-xia Yan, Xiu-mei Feng, Jun-ying Wang, Cheng-lin Duanmu, Shu-ping Chen, Yong-hui Gao, Yan-jing Han, Shuang-kun Wang, Jian-liang Zhang, Jun-ling Liu
OBJECTIVE: To observe the effect of electroacupuncture (EA) on expression of pain sensory and affective processing-related µ-opioid receptor (MOR), glutamatergic AMPA receptor subunit GIuA 1, extracellular signal-regulated kinase (ERK 1/2), cAMP response element binding protein(CREB) in the amygdala in chronic constrictive injury (CC) + negative affection(NA) rats, so as to reveal its mechanism underlying pain relief. METHODS: A total of 32 male Wistar rats were randomized into normal control, model, EA, and anesthesia+ EA (AEA) groups (n = 8 in each group)...
February 2016: Zhen Ci Yan Jiu, Acupuncture Research
Praveen Anand, Yiangos Yiangou, Uma Anand, Gaurav Mukerji, Marco Sinisi, Michael Fox, Anthony McQuillan, Tom Quick, Yuri E Korchev, Peter Hein
The nociceptin/orphanin FQ peptide receptor (NOP), activated by its endogenous peptide ligand nociceptin/orphanin FQ (N/OFQ), exerts several effects including modulation of pain signalling. We have examined, for the first time, the tissue distribution of the NOP receptor in clinical visceral and somatic pain disorders by immunohistochemistry and assessed functional effects of NOP and μ-opioid receptor activation in cultured human and rat dorsal root ganglion (DRG) neurons. Quantification of NOP-positive nerve fibres within the bladder suburothelium revealed a remarkable several-fold increase in detrusor overactivity (P < 0...
September 2016: Pain
P Sacerdote, F Coluzzi, A Fanelli
Despite the availability of national and international guidelines, adequate postoperative pain (POP) management is still a challenge in Italy. One of the potential reasons for the high incidence of surgical patients complaining moderate to severe pain is the difficult application of the currently recommended analgesic techniques in clinical practice. In particular, morphine, the most commonly used systemic opioid in the POP treatment, has some unfavorable pharmacodynamic and pharmacokinetic characteristics for POP management, suggesting a potential relevant improvement by using different opioids...
April 2016: European Review for Medical and Pharmacological Sciences
Egle M Mambretti, Katrin Kistner, Stefanie Mayer, Dominique Massotte, Brigitte L Kieffer, Carsten Hoffmann, Peter W Reeh, Alexander Brack, Esther Asan, Heike L Rittner
BACKGROUND: Opioids are the gold standard for the treatment of acute pain despite serious side effects in the central and enteric nervous system. µ-opioid receptors (MOPs) are expressed and functional at the terminals of sensory axons, when activated by exogenous or endogenous ligands. However, the presence and function of MOP along nociceptive axons remains controversial particularly in naïve animals. Here, we characterized axonal MOPs by immunofluorescence, ultrastructural, and functional analyses...
2016: Molecular Pain
Laura K Case, Marta Čeko, John L Gracely, Emily A Richards, Håkan Olausson, M Catherine Bushnell
Touch plays a significant role in human social behavior and social communication, and its rewarding nature has been suggested to involve opioids. Opioid blockade in monkeys leads to increased solicitation and receipt of grooming, suggesting heightened enjoyment of touch. We sought to study the role of endogenous opioids in perception of affective touch in healthy adults and in patients with fibromyalgia, a chronic pain condition shown to involve reduced opioid receptor availability. The pleasantness of touch has been linked to the activation of C-tactile fibers, which respond maximally to slow gentle touch and correlate with ratings of pleasantness...
January 2016: ENeuro
Ben A Chindo, Helmut Schröder, Andreas Koeberle, Oliver Werz, Axel Becker
ETHNOPHARMACOLOGICAL RELEVANCE: Extracts of the stem bark of Ficus platyphylla (FP) have been used in traditional the Nigerian medicine to treat psychoses, depression, epilepsy, pain and inflammation. Previous studies have revealed the analgesic and anti-inflammatory effects of FP in different assays including acetic acid-induced writhing, formalin-induced nociception, and albumin-induced oedema. PURPOSE/METHODS: In this study, we assessed the effects of the standardised extract of FP on hot plate nociceptive threshold and vocalisation threshold in response to electrical stimulation of the tail root in order to confirm its acclaimed analgesic properties...
May 26, 2016: Journal of Ethnopharmacology
M Al-Hashimi, J McDonald, J P Thompson, D G Lambert
BACKGROUND: While it is well known that opioids depress the immune system, the site(s) of action for this depression is highly controversial. Immune modulation could occur directly at the immune cell or centrally via the hypothalamic-pituitary-adrenal axis. In a number of studies using individual enriched immune cell populations we have failed to detect classical µ (MOP), δ (DOP) and κ (KOP) receptors. The non-classical nociceptin/orphanin FQ (N/OFQ) receptor (NOP) is expressed on all cells examined thus far...
March 2016: British Journal of Anaesthesia
Dymphy R Huntjens, Lia C Liefaard, Partha Nandy, Henk-Jan Drenth, An Vermeulen
BACKGROUND AND OBJECTIVE: Tapentadol is a centrally acting analgesic with two mechanisms of action, µ-opioid receptor agonism and noradrenaline reuptake inhibition. The objectives were to describe the pharmacokinetic behavior of tapentadol after oral administration of an extended-release (ER) formulation in healthy subjects and patients with chronic pain and to evaluate covariate effects. METHODS: Data were obtained from 2276 subjects enrolled in five phase I and nine phase II and III studies...
March 2016: Clinical Drug Investigation
Dhananjay P Thakur, Jin-bin Tian, Jaepyo Jeon, Jian Xiong, Yu Huang, Veit Flockerzi, Michael X Zhu
Transient Receptor Potential Canonical (TRPC) proteins form nonselective cation channels commonly known to be activated downstream from receptors that signal through phospholipase C (PLC). Although TRPC3/C6/C7 can be directly activated by diacylglycerols produced by PLC breakdown of phosphatidylinositol 4,5-bisphosphate (PIP2), the mechanism by which the PLC pathway activates TRPC4/C5 remains unclear. We show here that TRPC4 activation requires coincident stimulation of Gi/o subgroup of G proteins and PLCδ, with a preference for PLCδ1 over PLCδ3, but not necessarily the PLCβ pathway commonly thought to be involved in receptor-operated TRPC activation...
January 26, 2016: Proceedings of the National Academy of Sciences of the United States of America
Borje Darpo, Meijian Zhou, Stephen A Bai, Georg Ferber, Qinfang Xiang, Andrew Finn
PURPOSE: A thorough QT study was conducted in healthy subjects to evaluate the effect of buprenorphine hydrochloride administered through a buccal soluble film under coverage of naltrexone to block confounding, secondary QT effects. METHODS: Healthy subjects were enrolled in a randomized, partially blinded, 4-way crossover designed study. Subjects received buprenorphine 3 mg with naltrexone, naltrexone alone (with placebo films), placebo (placebo films and placebo naltrexone), and open-label moxifloxacin 400 mg with placebo naltrexone in separate in-house treatment periods...
February 2016: Clinical Therapeutics
Jacqueline A Hannam, Xavier Borrat, Iñaki F Trocóniz, José F Valencia, Erik W Jensen, Angela Pedroso, Jenifer Muñoz, Sergi Castellví-Bel, Antoni Castells, Pedro L Gambús
Respiratory depression is a common adverse effect of propofol and remifentanil. We aimed to develop a model for respiratory depressant effects of propofol with remifentanil in patients undergoing endoscopy with sedation. Data were available for 136 patients undergoing endoscopy with sedation. Participants randomly received infusions of propofol and remifentanil. Predicted plasma concentrations, outputted by infusion pumps, were available. Transcutaneous arterial pressure of carbon dioxide (pCO2) was measured...
March 2016: Journal of Pharmacology and Experimental Therapeutics
Kalpit N Shah, Gregory Waryasz, J Mason DePasse, Alan H Daniels
Postoperative ileus affects a substantial proportion of patients undergoing elective spine surgery, especially in cases of spinal deformity correction and where an anterior lumbar approach is utilized. Though the first line of treatment for postoperative ileus is conservative management, recent advances in pharmacology have yielded promising options for both treatment and prevention. We report a case of a patient who underwent a two-stage posterior spinal fusion. The patient suffered with a severe, prolonged ileus after her initial surgery...
September 28, 2015: Orthopedic Reviews
T Mettang, S Ständer, A E Kremer
Chronic itch (CI) is a frequent and sometimes tormenting symptom in many skin and systemic diseases. In systemic diseases, it mostly appears on primarily unaffected skin. As a sequelae of intense scratching, secondary skin lesions such as excoriations, scars, and prurigo nodularis may occur. Due to the lack of valid pathogenetic concepts and good clinical trials, the therapy of CI remains mostly symptomatic. In Europe almost all drugs used to treat CI are not approved for this indication. CI is frequent in patients with chronic kidney diseases in advanced stages...
December 2015: Der Internist
Zongming Jiang, Shaoyong Wu, Xiujuan Wu, Junfeng Zhong, Anqing Lv, Jing Jiao, Zhonghua Chen
The current study was to examine the underlying mechanisms responsible for the role of mammalian target of rapamycin (mTOR) in regulating bone cancer-evoked pain and the tolerance of systemic morphine. Breast sarcocarcinoma Walker 256 cells were implanted into the tibia bone cavity of rats and this evoked significant mechanical and thermal hyperalgesia. Our results showed that the protein expression of p-mTOR, mTOR-mediated phosphorylation of 4E-binding protein 4 (4E-BP1), p70 ribosomal S6 protein kinase 1 (S6K1) as well as phosphatidylinositide 3-kinase (p-PI3K) pathways were amplified in the superficial dorsal horn of the spinal cord of bone cancer rats compared with control rats...
April 15, 2016: International Journal of Cancer. Journal International du Cancer
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