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mu-opioid receptor

D Reiss, R A Ceredig, T Secher, J Boué, F Barreau, G Dietrich, C Gavériaux-Ruff
BACKGROUND: Opiates act through opioid receptors to diminish pain. Here, we investigated whether mu (MOR) and delta (DOR) receptor endogenous activity assessed in the whole mouse body or in particular at peripheral receptors on primary nociceptive neurons, control colonic pain. METHODS: We compared global MOR and DOR receptor knockout (KO) mice, mice with a conditional deletion of MOR and DOR in Nav1.8-positive nociceptive primary afferent neurons (cKO), and control floxed mice of both genders for visceral sensitivity...
October 17, 2016: European Journal of Pain: EJP
Gregory N Ruegsegger, Jacob D Brown, M Cathleen Kovarik, Dennis K Miller, Frank W Booth
The mesolimbic dopamine and opioid systems are postulated to influence the central control of physical activity motivation. We utilized selectively bred rats for high (HVR) or low (LVR) voluntary running behavior to examine 1) inherent differences in mu-opioid receptor (Oprm1) expression and function in the nucleus accumbens (NAc), 2) if dopamine-related mRNAs, wheel-running, and food intake are differently influenced by intraperitoneal (i.p.) naltrexone injection in HVR and LVR rats, and 3) if dopamine is required for naltrexone-induced changes in running and feeding behavior in HVR rats...
October 12, 2016: Neuroscience
Jianguo Zhuang, Xiuping Gao, Franklin Gao, Fadi Xu
We tested the hypothesis that mu-opioid receptors (MORs) in the caudomedial nucleus tractus solitarius (cmNTS) are important for the ventilatory responses to stimulation of bronchopulmonary C-fibers (PCFs), the carotid body-mediated hypoxia, and hypercapnia independent of the carotid body. First, we used immunohistochemistry to map MORs distribution in the caudal medulla. Then we compared the effects of intra-cmNTS microinjection of DAMGO (a MOR agonist) with or without a combination of CTAP (a MOR antagonist) on the ventilatory responses to: 1) right atrial injection of capsaicin (to stimulation of PCFs) and 2) acute hypoxia (HVR, to stimulate the carotid body) in awake intact rats; and 3) hypercapnia (HCVR) in the carotid body ablated rats...
October 12, 2016: Respiratory Physiology & Neurobiology
Marcelina Jasmine Silva, Andrea Rubinstein
Buprenorphine, a semisynthetic thebaine derivative, is a unique opioid, as it has activity at multiple receptors, including mu (partial agonist), kappa (antagonist), OLR-1 (agonist), and delta (antagonist). Because buprenorphine's pharmacology is relatively complex, misconceptions about its actions are common. Most other opioids act solely or predominately as full mu receptor agonists. Common practice at many institutions calls for the cessation of regular buprenorphine use 48-72 hours prior to surgery. This practice is based on three foundational theories that have come from scant data about the properties of buprenorphine: (1) that buprenorphine is only a partial mu agonist and therefore is not a potent analgesic; (2) because buprenorphine has a ceiling effect on respiratory depression, it also has a ceiling effect on analgesia; and (3) that buprenorphine acts as a "blockade" to the analgesic effects of other opiates when coadministered due to its strong binding affinity...
October 13, 2016: Journal of Pain & Palliative Care Pharmacotherapy
Sumita Chakrabarti, Andrew Chang, Nai-Jiang Liu, Alan R Gintzler
Caveolin-1 is the predominant structural protein of caveolae, a subset of (lipid) membrane rafts that compartmentalize cell signaling. Caveolin-1 binds most to G protein-coupled receptors and their signaling partners, thereby enhancing interactions among signaling cascade components and the relative activation of specific G protein-coupled pathways. This study reveals that chronic opioid exposure of μ-opioid receptor (MOR) expressing Chinese hamster ovary cells (MOR-CHO) and chronic in vivo morphine exposure of rat spinal cord augmented recruitment of multiple components of MOR-adenylyl cyclase (AC) stimulatory signaling by caveolin-1...
October 10, 2016: Journal of Neurochemistry
Eiko Yokota, Yuko Koyanagi, Kiyofumi Yamamoto, Yoshiyuki Oi, Noriaki Koshikawa, Masayuki Kobayashi
The insular cortex (IC) plays a principal role in the regulation of pain processing. Although opioidergic agonists depress cortical excitatory synaptic transmission, little is known about opioidergic roles in inhibitory synaptic transmission. In the IC, the opioid receptors differentially regulate the excitatory propagation: agonists of the mu (MOR), delta (DOR), and kappa (KOR) exhibit suppressive, facilitative, and little effects, respectively. Thus, we aimed to examine the effects of opioid receptor agonists on unitary inhibitory postsynaptic currents (uIPSCs) in the IC...
October 7, 2016: Neuroscience
Christopher K Arnatt, Bethany A Falls, Yunyun Yuan, Thomas J Raborg, Ruturaj R Masvekar, Nazira El-Hage, Dana E Selley, Anthony V Nicola, Pamela E Knapp, Kurt F Hauser, Yan Zhang
Modern antiretroviral therapies have provided HIV-1 infected patients longer lifespans and better quality of life. However, several neurological complications are now being seen in these patients due to HIV-1 associated injury of neurons by infected microglia and astrocytes. In addition, these effects can be further exacerbated with opiate use and abuse. One possible mechanism for such potentiation effects of opiates is the interaction of the mu opioid receptor (MOR) with the chemokine receptor CCR5 (CCR5), a known HIV-1 co-receptor, to form MOR-CCR5 heterodimer...
September 26, 2016: Bioorganic & Medicinal Chemistry
Xiao-Fei Wang, Elisabeth Barbier, Yi-Ting Chiu, Yi He, Jia Zhan, Guo-Hua Bi, Hai-Ying Zhang, Bo Feng, Lee-Yuan Liu-Chen, Jia Bei Wang, Zheng-Xiong Xi
: The etiology and pathophysiology underlying opioid tolerance and dependence are still unknown. Because mu opioid receptor (MOR) plays an essential role in opioid action, many vulnerability-related studies have focused on single nucleotide polymorphisms of MOR, particularly on A118G. In this study, we found that a single-point mutation at the MOR T394 phosphorylation site could be another important susceptive factor in the development of opioid tolerance and dependence in mice. T394A mutation, in which a threonine at 394 was replaced by an alanine, did not alter agonist binding to MOR and opioid analgesia, but resulted in loss of etorphine-induced MOR internalization in spinal dorsal horn neurons and opioid analgesic tolerance induced by either morphine or etorphine...
October 5, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Ashlee Van't Veer, Karen L Smith, Bruce M Cohen, William A Carlezon, Anita J Bechtholt
INTRODUCTION: Studies in laboratory animals and humans indicate that endogenous opioids play an important role in regulating the rewarding value of various drugs, including ethanol (EtOH). Indeed, opioid antagonists are currently a front-line treatment for alcoholism in humans. Although roles for mu- and delta-opioid receptors have been characterized, the contribution of kappa-opioid receptors (KORs) is less clear. There is evidence that changes in KOR system function can decrease or increase EtOH drinking, depending on test conditions...
September 2016: Brain and Behavior
Raphael Jorand, Sunetra Biswas, Devin L Wakefield, Steven J Tobin, Ottavia Golfetto, Kelsey Hilton, Michelle Ko, Joe W Ramos, Alexander R Small, Peiguo Chu, Gagandeep Singh, Tijana Jovanovic-Talisman
Pancreatic ductal adenocarcinoma (PDAC), a particularly aggressive malignancy, has been linked to atypical levels, certain mutations, and aberrant signaling of G-protein coupled receptors (GPCRs). GPCRs have been challenging to target in cancer because they organize into complex networks in tumor cells. To dissect such networks with nanometer-scale precision, traditional biochemical approaches were combined herein with super-resolution microscopy methods. A novel interaction specific to PDAC was identified between mu opioid receptor (MOR) and somatostatin receptor 2 (SSTR2)...
September 28, 2016: Molecular Biology of the Cell
Anna E Mechling, Tanzil Arefin, Hsu-Lei Lee, Thomas Bienert, Marco Reisert, Sami Ben Hamida, Emmanuel Darcq, Aliza Ehrlich, Claire Gaveriaux-Ruff, Maxime J Parent, Pedro Rosa-Neto, Jürgen Hennig, Dominik von Elverfeldt, Brigitte Lina Kieffer, Laura-Adela Harsan
Connectome genetics seeks to uncover how genetic factors shape brain functional connectivity; however, the causal impact of a single gene's activity on whole-brain networks remains unknown. We tested whether the sole targeted deletion of the mu opioid receptor gene (Oprm1) alters the brain connectome in living mice. Hypothesis-free analysis of combined resting-state fMRI diffusion tractography showed pronounced modifications of functional connectivity with only minor changes in structural pathways. Fine-grained resting-state fMRI mapping, graph theory, and intergroup comparison revealed Oprm1-specific hubs and captured a unique Oprm1 gene-to-network signature...
October 11, 2016: Proceedings of the National Academy of Sciences of the United States of America
Panayotis K Thanos, Jianmin Zhuo, Lisa Robison, Ronald Kim, Mala Ananth, Ilon Choai, Adam Grunseich, Nicola M Grissom, Robert George, Foteini Delis, Teresa M Reyes
Birthweight is a marker for suboptimal fetal growth and development in utero. Offspring can be born large for gestational age (LGA), which is linked to maternal obesity or excessive gestational weight gain, as well as small for gestational age (SGA), arising from nutrient or calorie deficiency, placental dysfunction, or other maternal conditions (hypertension, infection). In humans, LGA and SGA babies are at an increased risk for certain neurodevelopmental disorders, including Attention Deficit/Hyperactivity Disorder, schizophrenia, and social and mood disorders...
September 22, 2016: International Journal of Developmental Neuroscience
M Carmen Blanco-Gandía, Lídia Cantacorps, Auxiliadora Aracil-Fernández, Sandra Montagud-Romero, María A Aguilar, Jorge Manzanares, Olga Valverde, José Miñarro, Marta Rodríguez-Arias
Binge eating is a specific form of overeating characterized by intermittent excessive eating. In addition to altering the neurobiological reward system, several studies have highlighted that consumption of palatable food increases vulnerability to drug use. The aim of the present study was to evaluate the effects of a high-fat diet consumed in a binge pattern during adolescence on the reinforcing effects of cocaine. After 40 days of binge-eating for 2 h, three days a week (PND 29-69), the reinforcing effects of cocaine on conditioning place preference and intravenous self-administration paradigm were evaluated in adolescent male mice...
September 22, 2016: Neuropharmacology
Laura C Sullivan, Teresa A Chavera, Raehannah J Jamshidi, Kelly A Berg, William P Clarke
Opioid receptors expressed by peripheral pain-sensing neurons are functionally inactive for antinociceptive signaling under most basal conditions, however, tissue damage or exposure to inflammatory mediators (e.g., bradykinin) converts these receptors from a non-responsive state to a functionally competent state. Here we tested the hypothesis that the basal, non-responsive state of the mu and delta opioid receptors (MOR and DOR, respectively) is the result of constitutive receptor activity that activates desensitization mechanisms, resulting in MOR and DOR receptor systems that are constitutively desensitized...
September 22, 2016: Journal of Pharmacology and Experimental Therapeutics
Gina F Marrone, Zhigang Lu, Grace Rossi, Ankita Narayan, Amanda Hunkele, Sarah Marx, Jin Xu, John Pintar, Susruta Majumdar, Ying-Xian Pan, Gavril W Pasternak
The mu opioid receptor gene undergoes extensive alternative splicing. Mu opioids can be divided into three classes based on the role of different groups of splice variants. Morphine and methadone require only full length seven transmembrane (7TM) variants for analgesia, whereas IBNtxA (3'-iodobenzyol-6β-naltrexamide) needs only truncated 6TM variants. A set of endomorphin analogs fall into a third group that requires both 6TM and 7TM splice variants. Unlike morphine, endomorphin 1 and 2, DAPP (Dmt,d-Ala-Phe-Phe-NH2), and IDAPP (3'-iodo-Dmt-d-Ala-Phe-Phe-NH2) analgesia was lost in an exon 11 knockout mouse lacking 6TM variants...
October 10, 2016: ACS Chemical Neuroscience
Aishwarya Vijay, Shuo Wang, Patrick Worhunsky, Ming-Qiang Zheng, Nabeel Nabulsi, Jim Ropchan, Suchitra Krishnan-Sarin, Yiyun Huang, Evan D Morris
Opioid receptors may play critical roles in alcoholism and other addictions, addiction withdrawal, and depression and are considered pharmacological targets for treatment of these conditions. Sex differences have been demonstrated in mu (MOR) and delta (DOR) opioid receptors in humans, in vivo. In addition, sex differences have been observed in efficacy of treatment targeting kappa opioid receptors (KOR). Our goal in the present study was to compare the availability of KOR (1) between healthy control (HC) men and women...
2016: American Journal of Nuclear Medicine and Molecular Imaging
Edina Szűcs, Szabolcs Dvorácskó, Csaba Tömböly, Alexandra Büki, Gabriella Kékesi, Gyöngyi Horváth, Sándor Benyhe
Schizophrenia is a serious mental health disorder characterized by several behavioral and biochemicel abnormalities. In a previous study we have shown that mu-opioid (MOP) receptor signaling is impaired in specific brain regions of our three-hit animal model of schizophrenia. Since the cannabinoid system is significantly influenced in schizophrenic patients, in the present work we investigated cannabinoid (CB) receptor binding and G-protein activation in cortical, subcortical and cerebellar regions of control and 'schizophrenic' rats...
October 28, 2016: Neuroscience Letters
Jai Shankar K Yadlapalli, Benjamin M Ford, Amit Ketkar, Anqi Wan, Narasimha R Penthala, Robert L Eoff, Paul L Prather, Maxim Dobretsov, Peter A Crooks
: This study determined the antinociceptive effects of morphine and morphine-6-O-sulfate (M6S) in both normal and diabetic rats, and evaluated the comparative role of mu-opioid receptors (mu-ORs) and delta-opioid receptors (delta-ORs) in the antinociceptive action of these opioids. In vitro characterization of mu-OR and delta-OR-mediated signaling by M6S and morphine in stably transfected Chinese hamster ovary (CHO-K1) cells showed that M6S exhibited a 6-fold higher affinity for delta-ORs and modulated G-protein and adenylyl cyclase activity via delta-ORs more potently than morphine...
September 13, 2016: Pharmacological Research: the Official Journal of the Italian Pharmacological Society
K Wagner, K S S Lee, J Yang, B D Hammock
BACKGROUND: Neuropathic pain is a debilitating condition with no adequate therapy. The health benefits of omega-3 fatty acids are established, however, the role of docosahexaenoic acid (DHA) in limiting pain has only recently been described and the mechanisms of this action remain unknown. DHA is metabolized into epoxydocosapentanoic acids (EDPs) via cytochrome P450 (CYP450) enzymes which are substrates for the soluble epoxide hydrolase (sEH) enzyme. Here, we tested several hypotheses; first, that the antinociceptive action of DHA is mediated by the EDPs...
September 15, 2016: European Journal of Pain: EJP
Jeremy A Spool, Sharon A Stevenson, Caroline S Angyal, Lauren V Riters
Animals integrate social information with their internal endocrine state to control the timing of behavior, but how these signals are integrated in the brain is not understood. The medial preoptic area (mPOA) may play an integrative role in the control of courtship behavior, as it receives projections from multiple sensory systems, and is central to the hormonal control of courtship behavior across vertebrates. Additionally, data from many species implicate opioid and dopaminergic systems in the mPOA in the control of male courtship behavior...
September 12, 2016: Hormones and Behavior
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