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Mori T, Itoh T, Yoshizawa K, Ise Y, Mizuo K, Saeki T, Komiya S, Masukawa D, Shibasaki M, Suzuki T. Involvement of μ- and δ-opioid receptor function in the rewarding effect of (±)-pentazocine. Addict Biol 2015; 20:724-32. [PMID: 25065832 DOI: 10.1111/adb.12169] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Most opioid receptor agonists have abuse potential, and the rewarding effects of opioids can be reduced in the presence of pain. While each of the enantiomers of pentazocine has a differential pharmacologic profile, (±)-pentazocine has been used clinically for the treatment of pain. However, little information is available regarding which components of pentazocine are associated with its rewarding effects, and whether the (±)-pentazocine-induced rewarding effects can be suppressed under pain. Therefore, the present study was performed to investigate the effects of pain on the acquisition of the rewarding effects of (±)-pentazocine, and to examine the mechanism of the rewarding effects of (±)-pentazocine using the conditioned place preference paradigm. (±)-Pentazocine and (-)-pentazocine, but not (+)-pentazocine, produced significant rewarding effects. Even though the rewarding effects induced by (±)-pentazocine were significantly suppressed under pain induced by formalin, accompanied by increase of preprodynorphin mRNA levels in the nucleus accumbens, a high dose of (±)-pentazocine produced significant rewarding effects under pain. In the normal condition, (±)-pentazocine-induced rewarding effects were blocked by a low dose of naloxone, whereas the rewarding effects induced by high doses of pentazocine under pain were suppressed by naltrindole (a δ-opioid receptor antagonist). Interestingly, (±)-pentazocine did not significantly affect dopamine levels in the nucleus accumbens. These findings suggest that the rewarding effects of (-)-pentazocine may contribute to the abuse potential of (±)-pentazocine through μ- as well as δ-opioid receptors, without robust activation of the mesolimbic dopaminergic system. We also found that neural adaptations can reduce the abuse potential of (±)-pentazocine under pain.
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Affiliation(s)
- Tomohisa Mori
- Department of Toxicology; Hoshi University School of Pharmacy and Pharmaceutical Sciences; Tokyo Japan
| | - Toshimasa Itoh
- Department of Toxicology; Hoshi University School of Pharmacy and Pharmaceutical Sciences; Tokyo Japan
| | - Kazumi Yoshizawa
- Department of Toxicology; Hoshi University School of Pharmacy and Pharmaceutical Sciences; Tokyo Japan
| | - Yuya Ise
- Department of Toxicology; Hoshi University School of Pharmacy and Pharmaceutical Sciences; Tokyo Japan
| | - Keisuke Mizuo
- Department of Toxicology; Hoshi University School of Pharmacy and Pharmaceutical Sciences; Tokyo Japan
| | - Tomoya Saeki
- Department of Toxicology; Hoshi University School of Pharmacy and Pharmaceutical Sciences; Tokyo Japan
| | - Sachiko Komiya
- Department of Toxicology; Hoshi University School of Pharmacy and Pharmaceutical Sciences; Tokyo Japan
| | - Daiki Masukawa
- Department of Toxicology; Hoshi University School of Pharmacy and Pharmaceutical Sciences; Tokyo Japan
| | - Masahiro Shibasaki
- Department of Toxicology; Hoshi University School of Pharmacy and Pharmaceutical Sciences; Tokyo Japan
| | - Tsutomu Suzuki
- Department of Toxicology; Hoshi University School of Pharmacy and Pharmaceutical Sciences; Tokyo Japan
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Tsagareli MG, Tsiklauri N, Nozadze I, Gurtskaia G. Tolerance effects of non-steroidal anti-inflammatory drugs microinjected into central amygdala, periaqueductal grey, and nucleus raphe: Possible cellular mechanism. Neural Regen Res 2015; 7:1029-39. [PMID: 25722692 PMCID: PMC4341275 DOI: 10.3969/j.issn.1673-5374.2012.13.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 02/24/2012] [Indexed: 12/29/2022] Open
Abstract
Pain is a sensation related to potential or actual damage in some tissue of the body. The mainstay of medical pain therapy remains drugs that have been around for decades, like non-steroidal anti-inflammatory drugs (NSAIDs), or opiates. However, adverse effects of opiates, particularly tolerance, limit their clinical use. Several lines of investigations have shown that systemic (intraperitoneal) administration of NSAIDs induces antinociception with some effects of tolerance. In this review, we report that repeated microinjection of NSAIDs analgin, clodifen, ketorolac and xefocam into the central nucleus of amygdala, the midbrain periaqueductal grey matter and nucleus raphe magnus in the following 4 days result in progressively less antinociception compared to the saline control testing in the tail-flick reflex and hot plate latency tests. Hence, tolerance develops to these drugs and cross-tolerance to morphine in male rats. These findings strongly support the suggestion of endogenous opioid involvement in NSAIDs antinociception and tolerance in the descending pain-control system. Moreover, the periaqueductal grey-rostral ventro-medial part of medulla circuit should be viewed as a pain-modulation system. These data are important for human medicine. In particular, cross-tolerance between non-opioid and opioid analgesics should be important in the clinical setting.
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Affiliation(s)
- Merab G Tsagareli
- Ivane Beritashvili Experimental BioMedicine Center, Tbilisi 0160, Georgia
| | - Nana Tsiklauri
- Ivane Beritashvili Experimental BioMedicine Center, Tbilisi 0160, Georgia
| | - Ivliane Nozadze
- Ivane Beritashvili Experimental BioMedicine Center, Tbilisi 0160, Georgia
| | - Gulnaz Gurtskaia
- Ivane Beritashvili Experimental BioMedicine Center, Tbilisi 0160, Georgia
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Mori T, Kanbara T, Harumiya M, Iwase Y, Masumoto A, Komiya S, Nakamura A, Shibasaki M, Kanemasa T, Sakaguchi G, Suzuki T. Establishment of opioid-induced rewarding effects under oxaliplatin- and Paclitaxel-induced neuropathy in rats. J Pharmacol Sci 2014; 126:47-55. [PMID: 25141998 DOI: 10.1254/jphs.14134fp] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
The rewarding effects of μ-receptor agonists can be suppressed under several pain conditions. We recently showed that clinically used μ-receptor agonists possess efficacies for relieving the neuropathic pain induced by chemotherapeutic drug in rats; however, it is possible that the use of μ-receptor agonists may trigger the rewarding effects even under chemotherapeutic drug-induced neuropathic pain. Nevertheless, no information is available regarding whether μ-receptor agonists produce psychological dependence under chemotherapeutic drug-induced neuropathic pain. Therefore, we examined the effects of neuropathy induced by chemotherapeutic drugs on the rewarding effects of morphine, oxycodone, and fentanyl in rats. Repeated treatment with oxaliplatin or paclitaxel produced neuropathy as measured by the von Frey test. Rewarding effects produced by antinociceptive doses of μ-receptor agonists were not suppressed under oxaliplatin- or paclitaxel-induced neuropathy. Furthermore, the morphine-induced increase in the release of dopamine from the nucleus accumbens, which is a critical step in the rewarding effects of μ-receptor agonists, was not altered in paclitaxel-treated rats. These results suggest that the rewarding effects of μ-receptor agonists can still be established under oxaliplatin- or paclitaxel-induced neuropathic pain. Therefore, patients should be carefully monitored for psychological dependence on μ-receptor agonists when they are used to control chemotherapeutic drug-induced neuropathic pain.
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Affiliation(s)
- Tomohisa Mori
- Department of Toxicology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, Japan
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Woller SA, Malik JS, Aceves M, Hook MA. Morphine self-administration following spinal cord injury. J Neurotrauma 2014; 31:1570-83. [PMID: 24827476 DOI: 10.1089/neu.2013.3293] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Neuropathic pain develops in up to two-thirds of people following spinal cord injury (SCI). Opioids are among the most effective treatments for this pain and are commonly prescribed. There is concern surrounding the use of these analgesics, however, because use is often associated with the development of addiction. Previous data suggests that this concern may not be relevant in the presence of neuropathic pain. Yet, despite the common prescription of opioids for the treatment of SCI-related pain, there has been only one previous study examining the addictive potential of morphine following spinal injury. To address this, the present study used a self-administration paradigm to examine the addictive potential of morphine in a rodent model of SCI. Animals were placed into self-administration chambers 24 h, 14 d, or 35 d following a moderate spinal contusion injury. They were placed into the chambers for seven 12-hour sessions with access to 1.5 mg morphine/lever depression (up to 30 mg/d). In the acute phase of SCI, contused animals self-administered significantly less morphine than their sham counterparts, as previously shown. However, contused animals showing signs of neuropathic pain did not self-administer less morphine than their sham counterparts when administration began 14 or 35 d after injury. Instead, these animals administered nearly the full amount of morphine available each session. This amount of morphine did not affect recovery of locomotor function but did cause significant weight loss. We suggest caution is warranted when prescribing opioids for the treatment of neuropathic pain resulting from SCI, as the addictive potential is not reduced in this model.
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Affiliation(s)
- Sarah A Woller
- 1 Texas A&M University Institute for Neuroscience , Texas A&M Health Science Center, Bryan, Texas
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Elman I, Borsook D, Volkow ND. Pain and suicidality: insights from reward and addiction neuroscience. Prog Neurobiol 2013; 109:1-27. [PMID: 23827972 PMCID: PMC4827340 DOI: 10.1016/j.pneurobio.2013.06.003] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 06/03/2013] [Accepted: 06/18/2013] [Indexed: 01/09/2023]
Abstract
Suicidality is exceedingly prevalent in pain patients. Although the pathophysiology of this link remains unclear, it may be potentially related to the partial congruence of physical and emotional pain systems. The latter system's role in suicide is also conspicuous during setbacks and losses sustained in the context of social attachments. Here we propose a model based on the neural pathways mediating reward and anti-reward (i.e., allostatic adjustment to recurrent activation of the reward circuitry); both are relevant etiologic factors in pain, suicide and social attachments. A comprehensive literature search on neurobiology of pain and suicidality was performed. The collected articles were critically reviewed and relevant data were extracted and summarized within four key areas: (1) physical and emotional pain, (2) emotional pain and social attachments, (3) pain- and suicide-related alterations of the reward and anti-reward circuits as compared to addiction, which is the premier probe for dysfunction of these circuits and (4) mechanistically informed treatments of co-occurring pain and suicidality. Pain-, stress- and analgesic drugs-induced opponent and proponent states of the mesolimbic dopaminergic pathways may render reward and anti-reward systems vulnerable to sensitization, cross-sensitization and aberrant learning of contents and contexts associated with suicidal acts and behaviors. These findings suggest that pain patients exhibit alterations in the brain circuits mediating reward (depressed function) and anti-reward (sensitized function) that may affect their proclivity for suicide and support pain and suicidality classification among other "reward deficiency syndromes" and a new proposal for "enhanced anti-reward syndromes". We suggest that interventions aimed at restoring the balance between the reward and anti-reward networks in patients with chronic pain may help decreasing their suicide risk.
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Affiliation(s)
- Igor Elman
- Providence VA Medical Center and Cambridge Health Alliance, Harvard Medical School, 26 Central Street, Somerville, MA 02143, USA.
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Piaulino CA, Carvalho FCB, Almeida BC, Chaves MH, Almeida FRC, Brito SMRC. The stem bark extracts of Cenostigma macrophyllum attenuates tactile allodynia in streptozotocin-induced diabetic rats. PHARMACEUTICAL BIOLOGY 2013; 51:1243-1248. [PMID: 23844576 DOI: 10.3109/13880209.2013.786096] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
UNLABELLED CONTEXT. Cenostigma macrophyllum Tul. var. acuminata Teles Freire (Leguminosae- Caesalpinioideae) is popularly known as "caneleiro". Previous studies showed antioxidant action and analgesic effects of the ethanol extract from the leaves of C. macrophyllum. The phytochemical evaluation of the stem bark revealed the presence of antinociceptive compounds. OBJECTIVE To investigate the antinociceptive actions of the ethanol extract and ethyl acetate fraction from C. macrophyllum stem bark in streptozotocin (STZ)-induced diabetic rats and the involvement of opioid and nitrergic mechanisms. MATERIALS AND METHODS STZ-rats received the ethanol extract (E.EtOH 200 and 300 mg/kg, p.o.) during 5 weeks. In acute experiments, untreated diabetic rats were treated with the ethyl acetate fraction (F.EtOAc 250 and 500 mg/kg, p.o.), on the 28th day of diabetes induction when the opioid and nitrergic mechanisms were investigated. The mechanical nociceptive threshold (MNT) was determined by application of von Frey filaments. RESULTS Data show that STZ-induced diabetic rats developed a significant tactile allodynia during 5 weeks. Diabetic rats that received E.EtOH (200 and 300 mg/kg) and F.EtOAc (250 and 500 mg/kg) had a pain threshold higher than those in the STZ-vehicle group. F.EtOAc effects were inhibited by pretreatment with naloxone and were not influenced by .-arginine. DISCUSSION AND CONCLUSION The results suggest that the ethanol extract and ethyl acetate fraction of C. macrophyllum presented antinociceptive activity. Thus, F.EtOAc may be exerting its effect by affecting the opioid system, but nitrergic mechanisms are not detectable. The observed activity may be due to its gallic acid, lupeol and bergenin content.
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Affiliation(s)
- Celyane Alves Piaulino
- Department of Biochemistry and Pharmacology, Federal University of Piaui, Teresina-PI, Brazil
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Abstract
Mood disorders are common and debilitating conditions characterized in part by profound deficits in reward-related behavioural domains. A recent literature has identified important structural and functional alterations within the brain's reward circuitry--particularly in the ventral tegmental area-nucleus accumbens pathway--that are associated with symptoms such as anhedonia and aberrant reward-associated perception and memory. This Review synthesizes recent data from human and rodent studies from which emerges a circuit-level framework for understanding reward deficits in depression. We also discuss some of the molecular and cellular underpinnings of this framework, ranging from adaptations in glutamatergic synapses and neurotrophic factors to transcriptional and epigenetic mechanisms.
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Affiliation(s)
- Scott J Russo
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA. scott.russo@mssm. edu
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Rácz I, Markert A, Mauer D, Stoffel-Wagner B, Zimmer A. Long-term ethanol effects on acute stress responses: modulation by dynorphin. Addict Biol 2013; 18:678-88. [PMID: 22994904 DOI: 10.1111/j.1369-1600.2012.00494.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The brain stress-response system is critically involved in the addiction process, stimulating drug consumption and the relapse to drug taking in abstinent addicts. At the same time, its functioning is affected by chronic drug exposure. Here, we have investigated the role of the endogenous opioid peptide dynorphin as a modulator of effects of long-term ethanol consumption on the brain stress-response system. Using the two-bottle choice paradigm, we demonstrate an enhanced ethanol preference in male dynorphin knockout mice. Exposure to mild foot shock increased ethanol consumption in wild-type control littermates, but not in dynorphin-deficient animals. Blood adrenocorticotropic hormone levels determined 5 minutes after the shock were not affected by the genotype. We also determined the neuronal reactivity after foot shock exposure using c-Fos immunoreactivity in limbic structures. This was strongly influenced by both genotype and chronic ethanol consumption. Long-term alcohol exposure elevated the foot shock-induced c-Fos expression in the basolateral amygdala in wild-type animals, but had the opposite effect in dynorphin-deficient mice. An altered c-Fos reactivity was also found in the periventricular nucleus, the thalamus and the hippocampus of dynorphin knockouts. Together these data suggest that dynorphin plays an important role in the modulation of the brain stress-response systems after chronic ethanol exposure.
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Affiliation(s)
- Ildikó Rácz
- Institute of Molecular Psychiatry; University of Bonn; Bonn; Germany
| | - Astrid Markert
- Institute of Molecular Psychiatry; University of Bonn; Bonn; Germany
| | - Daniela Mauer
- Institute of Molecular Psychiatry; University of Bonn; Bonn; Germany
| | - Birgit Stoffel-Wagner
- Institute of Clinical Chemistry and Clinical Pharmacology; University of Bonn; Bonn; Germany
| | - Andreas Zimmer
- Institute of Molecular Psychiatry; University of Bonn; Bonn; Germany
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Yoshizawa K, Narita M, Suzuki T. [Psychological dependence on opioid analgesics]. Nihon Yakurigaku Zasshi 2013; 142:22-27. [PMID: 23842224 DOI: 10.1254/fpj.142.22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
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The application of conditioning paradigms in the measurement of pain. Eur J Pharmacol 2013; 716:158-68. [PMID: 23500202 DOI: 10.1016/j.ejphar.2013.03.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 02/25/2013] [Accepted: 03/03/2013] [Indexed: 12/13/2022]
Abstract
Pain is a private experience that involves both sensory and emotional components. Animal studies of pain can only be inferred by their responses, and therefore the measurement of reflexive responses dominates the pain literature for nearly a century. It has been argued that although reflexive responses are important to unveil the sensory nature of pain in organisms, pain affect is equally important but largely ignored in pain studies primarily due to the lack of validated animal models. One strategy to begin to understand pain affect is to use conditioning principles to indirectly reveal the affective condition of pain. This review critically analyzed several procedures that are thought to measure affective learning of pain. The procedures regarding the current knowledge, the applications, and their advantages and disadvantages in pain research are discussed. It is proposed that these procedures should be combined with traditional reflex-based pain measurements in future studies of pain, which could greatly benefit both the understanding of neural underpinnings of pain and preclinical assessment of novel analgesics.
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Doufas AG, Tian L, Padrez KA, Suwanprathes P, Cardell JA, Maecker HT, Panousis P. Experimental pain and opioid analgesia in volunteers at high risk for obstructive sleep apnea. PLoS One 2013; 8:e54807. [PMID: 23382975 PMCID: PMC3558510 DOI: 10.1371/journal.pone.0054807] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 12/17/2012] [Indexed: 01/20/2023] Open
Abstract
Background Obstructive sleep apnea (OSA) is characterized by recurrent nocturnal hypoxia and sleep disruption. Sleep fragmentation caused hyperalgesia in volunteers, while nocturnal hypoxemia enhanced morphine analgesic potency in children with OSA. This evidence directly relates to surgical OSA patients who are at risk for airway compromise due to postoperative use of opioids. Using accepted experimental pain models, we characterized pain processing and opioid analgesia in male volunteers recruited based on their risk for OSA. Methods After approval from the Intitutional Review Board and informed consent, we assessed heat and cold pain thresholds and tolerances in volunteers after overnight polysomnography (PSG). Three pro-inflammatory and 3 hypoxia markers were determined in the serum. Pain tests were performed at baseline, placebo, and two effect site concentrations of remifentanil (1 and 2 µg/ml), an μ-opioid agonist. Linear mixed effects regression models were employed to evaluate the association of 3 PSG descriptors [wake after sleep onset, number of sleep stage shifts, and lowest oxyhemoglobin saturation (SaO2) during sleep] and all serum markers with pain thresholds and tolerances at baseline, as well as their changes under remifentanil. Results Forty-three volunteers (12 normal and 31 with a PSG-based diagnosis of OSA) were included in the analysis. The lower nadir SaO2 and higher insulin growth factor binding protein-1 (IGFBP-1) were associated with higher analgesic sensitivity to remifentanil (SaO2, P = 0.0440; IGFBP-1, P = 0.0013). Other pro-inflammatory mediators like interleukin-1β and tumor necrosis factor-α (TNF-α) were associated with an enhanced sensitivity to the opioid analgesic effect (IL-1β, P = 0.0218; TNF-α, P = 0.0276). Conclusions Nocturnal hypoxemia in subjects at high risk for OSA was associated with an increased potency of opioid analgesia. A serum hypoxia marker (IGFBP-1) was associated with hypoalgesia and increased potency to opioid analgesia; other pro-inflammatory mediators also predicted an enhanced opioid potency. Trial Registration: ClinicalTrials.gov NCT00672737.
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Affiliation(s)
- Anthony G Doufas
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, California, USA.
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Obara I, Goulding SP, Gould AT, Lominac KD, Hu JH, Zhang PW, von Jonquieres G, Dehoff M, Xiao B, Seeburg PH, Worley PF, Klugmann M, Szumlinski KK. Homers at the Interface between Reward and Pain. Front Psychiatry 2013; 4:39. [PMID: 23761764 PMCID: PMC3675508 DOI: 10.3389/fpsyt.2013.00039] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 05/10/2013] [Indexed: 11/13/2022] Open
Abstract
Pain alters opioid reinforcement, presumably via neuroadaptations within ascending pain pathways interacting with the limbic system. Nerve injury increases expression of glutamate receptors and their associated Homer scaffolding proteins throughout the pain processing pathway. Homer proteins, and their associated glutamate receptors, regulate behavioral sensitivity to various addictive drugs. Thus, we investigated a potential role for Homers in the interactions between pain and drug reward in mice. Chronic constriction injury (CCI) of the sciatic nerve elevated Homer1b/c and/or Homer2a/b expression within all mesolimbic structures examined and for the most part, the Homer increases coincided with elevated mGluR5, GluN2A/B, and the activational state of various down-stream kinases. Behaviorally, CCI mice showed pain hypersensitivity and a conditioned place-aversion (CPA) at a low heroin dose that supported conditioned place-preference (CPP) in naïve controls. Null mutations of Homer1a, Homer1, and Homer2, as well as transgenic disruption of mGluR5-Homer interactions, either attenuated or completely blocked low-dose heroin CPP, and none of the CCI mutant strains exhibited heroin-induced CPA. However, heroin CPP did not depend upon full Homer1c expression within the nucleus accumbens (NAC), as CPP occurred in controls infused locally with small hairpin RNA-Homer1c, although intra-NAC and/or intrathecal cDNA-Homer1c, -Homer1a, and -Homer2b infusions (to best mimic CCI's effects) were sufficient to blunt heroin CPP in uninjured mice. However, arguing against a simple role for CCI-induced increases in either spinal or NAC Homer expression for heroin CPA, cDNA infusion of our various cDNA constructs either did not affect (intrathecal) or attenuated (NAC) heroin CPA. Together, these data implicate increases in glutamate receptor/Homer/kinase activity within limbic structures, perhaps outside the NAC, as possibly critical for switching the incentive motivational properties of heroin following nerve injury, which has relevance for opioid psychopharmacology in individuals suffering from neuropathic pain.
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Affiliation(s)
- Ilona Obara
- Department of Psychology, Neuroscience Research Institute, University of California at Santa Barbara Santa Barbara, CA, USA ; School of Medicine, Pharmacy and Health, Queen's Campus, University of Durham Stockton on Tees, UK
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Butelman ER, Kreek MJ. Kappa Opioids: Problems and Opportunities in Analgesia. ACS SYMPOSIUM SERIES 2013. [DOI: 10.1021/bk-2013-1131.ch013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Eduardo R. Butelman
- Laboratory on the Biology of Addictive Diseases, The Rockefeller University, New York, New York 10065
| | - Mary Jeanne Kreek
- Laboratory on the Biology of Addictive Diseases, The Rockefeller University, New York, New York 10065
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Yamaguchi T, Narita M, Morita T, Kizawa Y, Matoba M. Recent Developments in the Management of Cancer Pain in Japan: Education, Clinical Guidelines and Basic Research. Jpn J Clin Oncol 2012; 42:1120-7. [DOI: 10.1093/jjco/hys155] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Mori T, Shibasaki M, Abe M, Udagawa Y, Suzuki T. Effects of dronabinol on morphine-induced dopamine-related behavioral effects in animals. Synapse 2012; 66:931-7. [PMID: 22807156 DOI: 10.1002/syn.21586] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 07/06/2012] [Accepted: 07/10/2012] [Indexed: 11/12/2022]
Abstract
The present study examined the effects of dronabinol, a United States FDA-approved synthetic cannabinoid receptor agonist, on morphine (a prototypic μ-opioid receptor agonist)-induced dopamine-related behaviors in animals. Dronabinol suppressed the rewarding effects of morphine in rats and its emetic effects in ferrets. Furthermore, the morphine-induced increase in dopamine release from the nucleus accumbens was significantly attenuated by dronabinol, which indicated that the suppressive effects of dronabinol on morphine-induced behaviors are at least in part mediated by regulation of the dopaminergic system. Since cannabinoid receptor agonists have been shown to enhance the antinociceptive effects of morphine, the use of dronabinol as an adjuvant could be useful for preventing the adverse effects of μ-opioid receptor agonists when used to control pain.
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Affiliation(s)
- Tomohisa Mori
- Department of Toxicology, School of Pharmacy, Hoshi University School of Pharmacy and Pharmaceutical Sciences, Tokyo, Japan
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Intracranial self-stimulation of the paraventricular nucleus of the hypothalamus: increased faciliation by morphine compared to cocaine. Anesthesiology 2012; 116:1116-23. [PMID: 22421421 DOI: 10.1097/aln.0b013e3182518be3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Neuropathic pain attenuates opioid facilitation of rewarding electrical stimulation of limbic dopaminergic pathways originating from the ventral tegmental area. Whether neuropathic pain alters opioid effects of other brain-reward systems is unknown. METHODS Control and spinal nerve-ligated (SNL) rats had electrodes implanted into the paraventricular nucleus (PVN) of the hypothalamus or medial forebrain bundle. Control and SNL rats were trained to lever-press for intracranial self-stimulation (ICSS), and modulation by morphine or cocaine was assessed. RESULTS Control and SNL rats lever-pressed for stimulation of the PVN and medial forebrain bundle. Morphine produced greater reductions in the frequency at which rats emitted 50% of maximal responding for PVN ICSS (maximal effect 24.67 ± 4.60 [mean ± SEM] and 24.11 ± 5.96 in SNL [n = 6] and control [n = 8] rats, respectively, compared with medial forebrain bundle ICSS (12.38 ± 6.77 [n = 8] and 12.69 ± 1.55 [n = 7]). In contrast, cocaine was less efficacious in potentiating PVN ICSS (maximal effect 11.76 ± 2.86 and 12.38 ± 4.01 in SNL [n = 12] and control [n = 8] rats, respectively) compared with medial forebrain bundle ICSS (30.58 ± 3.40 [n = 9] and 27.55 ± 4.51 [n = 7]). CONCLUSIONS PVN ICSS is facilitated to a greater extent by morphine than cocaine, and the effects of each drug on this behavior are unaltered after spinal nerve ligation. These effects contrast those observed with direct stimulation of limbic dopamine pathways, suggesting that the PVN may have a greater role in the reinforcing effects of opioids than classic limbic regions, particularly in the presence of chronic pain.
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Lee JS, Kim SG, Kim HK, Baek SY, Kim CM. Acute effects of capsaicin on proopioimelanocortin mRNA levels in the arcuate nucleus of Sprague-Dawley rats. Psychiatry Investig 2012; 9:187-90. [PMID: 22707971 PMCID: PMC3372568 DOI: 10.4306/pi.2012.9.2.187] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 01/05/2012] [Accepted: 01/05/2012] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Capsaicin, a noxious stimulant and main component of the hot flavor of red peppers, has an analgesic effect when administered to humans. We investigated the expression of proopioimelanocortin (POMC) mRNA in the arcuate nucleus of Sprague-Dawley (SD) rats after administering capsaicin, hypothesizing that administering capsaicin activates the central opioid system. METHODS SD rats were divided randomly into two groups; one group received a saline injection and the other received a capsaicin injection. The POMC mRNA level in the arcuate nucleus of the hypothalamus was measured by the reverse transcription-polymerase chain reaction at 0, 20, 40, 60, and 120 minutes after capsaicin administration. RESULTS Capsaicin administration resulted in a significantly increased POMC mRNA level, compared to that in saline-treated rats at the 20-minute time point (t=-4.445, p=0.001). However, no significant group differences were observed at other times (t=-1.886, p=0.089; t= -0.973, p=0.353; t=-2.193, p=0.053 for 40, 60, and 120 minutes, respectively). CONCLUSION The analgesic effect of capsaicin might be associated with increased activity of the cerebral opioid system. This finding suggests that capsaicin acted for nociception and analgesia and could affect alcohol-intake behavior, which might further imply that a food culture could affect drinking behavior.
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Affiliation(s)
- Jin-Seong Lee
- Department of Psychiatry, Pusan National University Yangsan Hospital, Yangsan, Korea
| | - Sung-Gon Kim
- Department of Psychiatry, Pusan National University School of Medicine, Yangsan, Korea
| | - Hyeun-Kyeung Kim
- Medical Research Institute, Pusan National University, Busan, Korea
| | - Sun-Yong Baek
- Department of Anatomy, Pusan National University School of Medicine, Yangsan, Korea
| | - Cheol-Min Kim
- Department of Biochemistry, Pusan National University School of Medicine, Yangsan, Korea
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Rizk MK, Tolba R, Kapural L, Mitchell J, Lopez R, Mahboobi R, Vrooman B, Mekhail N. Differential epidural block predicts the success of visceral block in patients with chronic visceral abdominal pain. Pain Pract 2012; 12:595-601. [PMID: 22471927 DOI: 10.1111/j.1533-2500.2012.00548.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND AND AIMS Differential thoracic epidural regional block, also known as a differential neural block (DNB), involves the placement of an epidural catheter placed in the thoracic epidural space to achieve appropriate anesthesia in a dermatomal distribution. This is a retrospective case series evaluating how well a DNB may predict success of subsequent visceral blockade in patients with chronic abdominal pain of visceral origin. METHODS Of 402 patients who had a DNB performed for unexplained abdominal pain from January 2000 to January 2009, 81 patients were found to have results consistent with visceral pain and thus underwent subsequent visceral blockade. Basic demographic data, years of chronic pain, history of psychosocial issues, initial visual analog scale (VAS) pain score, pain location, and medication usage were documented in our electronic medical record database. Parameters regarding DNB and visceral blocks also were documented. Descriptive statistics were computed for all variables. The positive predictive value (PPV) for DNB for whom visceral block was successful (at least a 50% reduction in VAS) was calculated. Additionally, subjects with successful visceral blocks were compared to those with unsuccessful visceral blocks. PARTICIPANTS All patients with chronic abdominal pain with normal gastrointestinal studies who underwent DNB. SETTING Tertiary Outpatient Pain Management Clinic. DESIGN Retrospective Cohort Study. RESULTS Mean age of patients was 46 (± 15) years, 73% were female, and median duration of pain was 5 years. 67% of subjects were taking opioid analgesics. PPV of DNB was 70.4%. Only factor found to be statistically significant with visceral block success was baseline VAS with higher scores associated with DNB predictive success (6.8 ± 1.7 vs. 5.5, 1.8; P = 0.004). Use of membrane stabilizing medications was significantly more common in subjects for whom visceral block was not successful (46% vs. 25%; P = 0.058). Area underneath curve (AUC) for VAS was found to be 0.70 (95% CI: 0.57, 0.82), which signifies fair discrimination. CONCLUSION Differential neural block is fairly predictive of subsequent visceral block success in patients with chronic abdominal pain of visceral origin. An initial VAS ≥ 5 provides a sensitivity of 93%, which implies that VAS < 5 may predict unsuccessful visceral block. Contrarily, a value of ≥ 8 would provide a specificity of 92% and may be used to predict success of subsequent visceral block.
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Affiliation(s)
- Maged K Rizk
- Digestive Disease Institute, Cleveland Clinic, Cleveland, OH, USA.
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71
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Rewarding electrical brain stimulation in rats after peripheral nerve injury: decreased facilitation by commonly abused prescription opioids. Anesthesiology 2012; 115:1271-80. [PMID: 21946150 DOI: 10.1097/aln.0b013e3182330448] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Prescription opioid abuse is a significant concern in treating chronic pain, yet few studies examine how neuropathic pain alters the abuse liability of commonly abused prescription opioids. METHODS Normal and spinal nerve ligated (SNL) rats were implanted with electrodes into the left ventral tegmental area (VTA). Rats were trained to lever press for intracranial electrical stimulation (VTA ICSS), and the effects of methadone, fentanyl, hydromorphone, and oxycodone on facilitation of VTA ICSS were assessed. A second group of neuropathic rats were implanted with intrathecal catheters, and the effects of intrathecal clonidine, adenosine, and gabapentin on facilitation of VTA ICSS were assessed. The effects of electrical stimulation of the VTA on mechanical allodynia were assessed in SNL rats. RESULTS Responding for VTA ICSS was similar in control and SNL rats. Methadone, fentanyl, and hydromorphone were less potent in facilitating VTA ICSS in SNL rats. Oxycodone produced a significant facilitation of VTA ICSS in control (maximum shift 24.10 ± 6.19 Hz) but not SNL rats (maximum shift 16.32 ± 7.49 Hz), but also reduced maximal response rates in SNL rats. Intrathecal administration of clonidine, adenosine, and gabapentin failed to facilitate VTA ICSS in SNL rats, and electrical stimulation of the VTA did not alter mechanical allodynia following nerve injury. CONCLUSIONS The present data suggests that the positive reinforcing effects of commonly abused prescription opioids are diminished following nerve injury. In addition, alleviation of mechanical allodynia with nonopioid analgesics does not appear to stimulate limbic dopamine pathways originating from the VTA in SNL rats.
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72
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Change in microRNAs associated with neuronal adaptive responses in the nucleus accumbens under neuropathic pain. J Neurosci 2011; 31:15294-9. [PMID: 22031875 DOI: 10.1523/jneurosci.0921-11.2011] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neuropathic pain is the most difficult type of pain to control, and patients lose their motivation for the purposive pursuit with a decrease in their quality of life. Using a functional magnetic resonance imaging analysis, we demonstrated that blood oxygenation level-dependent signal intensity was increased in the ipsilateral nucleus accumbens (N.Acc.) following peripheral nerve injury. microRNAs are small, noncoding RNA molecules that direct the post-transcriptional suppression of gene expression, and play an important role in regulating synaptic plasticity. In this study, we found that sciatic nerve ligation induced a drastic decrease in the expression of miR200b and miR429 in N.Acc. neurons. The expression of DNA methyltransferase 3a (DNMT3a), which is the one of the predicted targets of miR200b/429, was significantly increased in the limbic forebrain including N.Acc. at 7 d after sciatic nerve ligation. Double-immunolabeling with antibodies specific to DNMT3a and NR1 showed that DNMT3a-immunoreactivity in the N.Acc. was located in NR1-labeled neurons, indicating that increased DNMT3a proteins were dominantly expressed in postsynaptic neurons in the N.Acc. area under a neuropathic pain-like state. The results of these analyses provide new insight into an epigenetic modification that is accompanied by a dramatic decrease in miR200b and miR429 along with the dysfunction of "mesolimbic motivation/valuation circuitry" under a neuropathic pain-like state. These phenomena may result in an increase in DNMT3a in neurons of the N.Acc. under neuropathic pain, which leads to the long-term transcription-silencing of several genes.
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73
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Üçeyler N, Topuzoğlu T, Schiesser P, Hahnenkamp S, Sommer C. IL-4 deficiency is associated with mechanical hypersensitivity in mice. PLoS One 2011; 6:e28205. [PMID: 22164245 PMCID: PMC3229527 DOI: 10.1371/journal.pone.0028205] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 11/03/2011] [Indexed: 12/27/2022] Open
Abstract
Interleukin-4 (IL-4) is an anti-inflammatory and analgesic cytokine that induces opioid receptor transcription. We investigated IL-4 knockout (ko) mice to characterize their pain behavior before and after chronic constriction injury (CCI) of the sciatic nerve as a model for neuropathic pain. We investigated opioid responsivity and measured cytokine and opioid receptor gene expression in the peripheral and central nervous system (PNS, CNS) of IL-4 ko mice in comparison with wildtype (wt) mice. Naïve IL-4 ko mice displayed tactile allodynia (wt: 0.45 g; ko: 0.18 g; p<0.001), while responses to heat and cold stimuli and to muscle pressure were not different. No compensatory changes in the gene expression of tumor necrosis factor-alpha (TNF), IL-1β, IL-10, and IL-13 were found in the PNS and CNS of naïve IL-4 ko mice. However, IL-1β gene expression was stronger in the sciatic nerve of IL-4 ko mice (p<0.001) 28 days after CCI and only IL-4 ko mice had elevated IL-10 gene expression (p = 0.014). Remarkably, CCI induced TNF (p<0.01), IL-1β (p<0.05), IL-10 (p<0.05), and IL-13 (p<0.001) gene expression exclusively in the ipsilateral spinal cord of IL-4 ko mice. The compensatory overexpression of the anti-inflammatory and analgesic cytokines IL-10 and IL-13 in the spinal cord of IL-4 ko mice may explain the lack of genotype differences for pain behavior after CCI. Additionally, CCI induced gene expression of μ, κ, and δ opioid receptors in the contralateral cortex and thalamus of IL-4 ko mice, paralleled by fast onset of morphine analgesia, but not in wt mice. We conclude that a lack of IL-4 leads to mechanical sensitivity; the compensatory hyperexpression of analgesic cytokines and opioid receptors after CCI, in turn, protects IL-4 ko mice from enhanced pain behavior after nerve lesion.
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Affiliation(s)
- Nurcan Üçeyler
- Department of Neurology, University of Würzburg, Würzburg, Germany.
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Abstract
This paper is the thirty-third consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2010 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration (Section 16); and immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, Flushing, NY 11367, USA.
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75
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Torigoe K, Mori T, Shibasaki M, Yoshizawa K, Narita M, Suzuki T. Olanzapine suppresses the rewarding and discriminative stimulus effects induced by morphine. Synapse 2011; 66:174-9. [DOI: 10.1002/syn.21500] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 10/17/2011] [Indexed: 12/23/2022]
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Guo W, Wang H, Zou S, Gu M, Watanabe M, Wei F, Dubner R, Huang GTJ, Ren K. Bone marrow stromal cells produce long-term pain relief in rat models of persistent pain. Stem Cells 2011; 29:1294-303. [PMID: 21630378 DOI: 10.1002/stem.667] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Chronic pain conditions are difficult to treat and are major health problems. Bone marrow stromal cells (BMSCs) have generated considerable interest as a candidate for cell-based therapy. BMSCs are readily accessible and are easy to isolate and expand ex vivo. Clinical studies show that direct injection of BMSCs does not produce unwanted side effects and is well tolerated and safe. Here, we show that a single systemic (intravenous) or local injection (into the lesion site) of rat primary BMSCs reversed pain hypersensitivity in rats after injury and that the effect lasted until the conclusion of the study at 22 weeks. The pain hypersensitivity was rekindled by naloxone hydrochloride, an opioid receptor antagonist that acts peripherally and centrally, when tested at 1-5 weeks after BMSC infusion. In contrast, naloxone methiodide, a peripherally acting opioid receptor antagonist, only rekindled hyperalgesia in the first 3 weeks of BMSC treatment. Focal downregulation of brainstem mu opioid receptors by RNA interference (RNAi) reversed the effect of BMSCs, when RNAi was introduced at 5- but not 1-week after BMSC transplantation. Thus, BMSCs produced long-term relief of pain and this effect involved activation of peripheral and central opioid receptors in distinct time domains. The findings prompt studies to elucidate the cellular mechanisms of the BMSC-induced pain relieving effect and translate these observations into clinical settings.
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Affiliation(s)
- Wei Guo
- Department of Neural and Pain Sciences, Dental School, University of Maryland, Baltimore, Maryland 21201-1586, USA
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77
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Viet CT, Schmidt BL. Biologic mechanisms of oral cancer pain and implications for clinical therapy. J Dent Res 2011; 91:447-53. [PMID: 21972258 DOI: 10.1177/0022034511424156] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Cancer pain is an ever-present public health concern. With innovations in treatment, cancer patients are surviving longer, but uncontrollable pain creates a poor quality of life for these patients. Oral cancer is unique in that it causes intense pain at the primary site and significantly impairs speech, swallowing, and masticatory functions. We propose that oral cancer pain has underlying biologic mechanisms that are generated within the cancer microenvironment. A comprehensive understanding of key mediators that control cross-talk between the cancer and peripheral nervous system, and possible interventions, underlies effective cancer pain management. The purpose of this review is to explore the current studies on oral cancer pain and their implications in clinical management for cancer pain in general. Furthermore, we will explore the endogenous opioid systems and novel cancer pain therapeutics that target these systems, which could solve the issue of opiate tolerance and improve quality of life in oral cancer patients.
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Affiliation(s)
- C T Viet
- Department of Oral Maxillofacial Surgery, New York University College of Dentistry, 421 First Avenue, 233W, New York, NY 10010, USA
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78
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Lee MR, Gallen CL, Zhang X, Hodgkinson CA, Goldman D, Stein EA, Barr CS. Functional polymorphism of the mu-opioid receptor gene (OPRM1) influences reinforcement learning in humans. PLoS One 2011; 6:e24203. [PMID: 21912675 PMCID: PMC3166306 DOI: 10.1371/journal.pone.0024203] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Accepted: 08/06/2011] [Indexed: 01/28/2023] Open
Abstract
Previous reports on the functional effects (i.e., gain or loss of function), and phenotypic outcomes (e.g., changes in addiction vulnerability and stress response) of a commonly occurring functional single nucleotide polymorphism (SNP) of the mu-opioid receptor (OPRM1 A118G) have been inconsistent. Here we examine the effect of this polymorphism on implicit reward learning. We used a probabilistic signal detection task to determine whether this polymorphism impacts response bias to monetary reward in 63 healthy adult subjects: 51 AA homozygotes and 12 G allele carriers. OPRM1 AA homozygotes exhibited typical responding to the rewarded response--that is, their bias to the rewarded stimulus increased over time. However, OPRM1 G allele carriers exhibited a decline in response to the rewarded stimulus compared to the AA homozygotes. These results extend previous reports on the heritability of performance on this task by implicating a specific polymorphism. Through comparison with other studies using this task, we suggest a possible mechanism by which the OPRM1 polymorphism may confer reduced response to natural reward through a dopamine-mediated decrease during positive reinforcement learning.
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Affiliation(s)
- Mary R Lee
- National Institute on Drug Abuse, Intramural Research Program, Baltimore, Maryland, United States of America.
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79
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Hahm ET, Kim Y, Lee JJ, Cho YW. GABAergic synaptic response and its opioidergic modulation in periaqueductal gray neurons of rats with neuropathic pain. BMC Neurosci 2011; 12:41. [PMID: 21569381 PMCID: PMC3103474 DOI: 10.1186/1471-2202-12-41] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Accepted: 05/12/2011] [Indexed: 11/10/2022] Open
Abstract
Background Neuropathic pain is a chronic and intractable symptom associated with nerve injury. The periaqueductal gray (PAG) is important in the endogenous pain control system and is the main site of the opioidergic analgesia. To investigate whether neuropathic pain affects the endogenous pain control system, we examined the effect of neuropathic pain induced by sacral nerve transection on presynaptic GABA release, the kinetics of postsynaptic GABA-activated Cl- currents, and the modulatory effect of μ-opioid receptor (MOR) activation in mechanically isolated PAG neurons with functioning synaptic boutons. Results In normal rats, MOR activation inhibited the frequency of GABAergic miniature inhibitory postsynaptic currents (mIPSCs) to 81.3% of the control without any alteration in their amplitude. In neuropathic rats, the inhibition of mIPSC frequency by MOR activation was 82.4%. The frequency of GABAergic mIPSCs in neuropathic rats was 151.8% of normal rats without any difference in the mIPSC amplitude. Analysis of mIPSC kinetics showed that the fast decay time constant and synaptic charge transfer of mIPSCs in neuropathic rats were 76.0% and 73.2% of normal rats, respectively. Conclusions These results indicate that although the inhibitory effect of MOR activation on presynaptic GABA release is similar in both neuropathic and normal rats, neuropathic pain may inhibit endogenous analgesia in the PAG through an increase in presynaptic GABA release.
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Affiliation(s)
- Eu-Teum Hahm
- Department of Physiology, Biomedical Science Institute, Kyung Hee University School of Medicine, Seoul 130-701, South Korea
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80
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Umberg EN, Pothos EN. Neurobiology of aversive states. Physiol Behav 2011; 104:69-75. [PMID: 21549137 DOI: 10.1016/j.physbeh.2011.04.045] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Revised: 04/23/2011] [Accepted: 04/26/2011] [Indexed: 12/01/2022]
Abstract
Hoebel and colleagues are often known as students of reward and how it is coded in the CNS. This article, however, attempts to focus on the significant advances by Hoebel and others in dissecting out behavioral components of distinct aversive states and in understanding the neurobiology of aversion and the link between aversive states and addictive behaviors. Reward and aversion are not necessarily dichotomous and may reflect an affective continuum contingent upon environmental conditions. Descriptive and mechanistic studies pioneered by Bart Hoebel have demonstrated that the shift in the reward-aversion spectrum may be, in part, a result of changes in central dopamine/acetylcholine ratio, particularly in the nucleus accumbens. The path to aversion appears to include a specific neurochemical signature: reduced dopamine release and increased acetylcholine release in "reward centers" of the brain. Opioid receptors may have a neuromodulatory role on both of these neurotransmitters.
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Affiliation(s)
- Erin N Umberg
- Department of Molecular Physiology and Pharmacology, Tufts University School of Medicine, Boston, MA 02111, United States
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81
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Mase H, Sakai A, Sakamoto A, Suzuki H. A subset of μ-opioid receptor-expressing cells in the rostral ventromedial medulla contribute to thermal hyperalgesia in experimental neuropathic pain. Neurosci Res 2011; 70:35-43. [DOI: 10.1016/j.neures.2011.01.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Revised: 12/29/2010] [Accepted: 01/05/2011] [Indexed: 01/08/2023]
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82
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Current world literature. Curr Opin Support Palliat Care 2011; 5:174-83. [PMID: 21521986 DOI: 10.1097/spc.0b013e3283473351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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83
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Imai S, Sudo Y, Nakamura A, Ozeki A, Asato M, Hojo M, Devi LA, Kuzumaki N, Suzuki T, Uezono Y, Narita M. Possible involvement of β-endorphin in a loss of the coordinated balance of μ-opioid receptors trafficking processes by fentanyl. Synapse 2011; 65:962-6. [PMID: 21437993 DOI: 10.1002/syn.20930] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 03/04/2011] [Indexed: 01/01/2023]
Affiliation(s)
- Satoshi Imai
- Department of Toxicology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan
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Hirouchi M, Tanaka M, Nishimura T. [Pharmacological profiles and clinical roles of tramadol hydrochloride (Tramal(®) capsules 25 mg·50 mg) in the treatment of cancer pain]. Nihon Yakurigaku Zasshi 2011; 137:189-197. [PMID: 21478640 DOI: 10.1254/fpj.137.189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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