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Sif-Eddine W, Ba-M'hamed S, Lefranc B, Leprince J, Boukhzar L, Anouar Y, Bennis M. Selenoprotein T, a potential treatment of attention-deficit/hyperactivity disorder and comorbid pain in neonatal 6-OHDA lesioned mice. Exp Mol Pathol 2024; 137:104905. [PMID: 38797131 DOI: 10.1016/j.yexmp.2024.104905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Revised: 05/21/2024] [Accepted: 05/22/2024] [Indexed: 05/29/2024]
Abstract
pathological pain and Attention-deficit/hyperactivity disorder (ADHD) are two complex multifactorial syndromes. The comorbidity of ADHD and altered pain perception is well documented in children, adolescents, and adults. According to pathophysiological investigations, the dopaminergic system's dysfunction provides a common basis for ADHD and comorbid pain. Growing evidence suggests that oxidative stress may be crucial in both pathologies. Recent studies revealed that a small peptide encompassing the redox-active site of selenoprotein T (PSELT), protects dopaminergic neurons and fibers as well as lesioned nerves in animal models. The current study aims to examine the effects of PSELT treatment on ADHD-like symptoms and pain sensitivity, as well as the role of catecholaminergic systems in these effects. Our results demonstrated that intranasal administration of PSELT reduced the hyperactivity in the open field, decreased the impulsivity displayed by 6-OHDA-lesioned male mice in the 5-choice serial reaction time task test and improved attentional performance. In addition, PSELT treatment significantly increased the nociception threshold in both normal and inflammatory conditions. Furthermore, anti-hyperalgesic activity was antagonized with sulpiride pre-treatment, but not by phentolamine, or propranolol pre-treatments. The present study suggests that PSELT reduces the severity of ADHD symptoms in mice and possesses potent antinociceptive effects which could be related to the involvement of D2/D3 dopaminergic receptors.
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Affiliation(s)
- Wahiba Sif-Eddine
- Laboratory of Pharmacology, Neurobiology, Anthropobiology, and Environment, Faculty of Sciences, Cadi Ayyad University, Marrakesh, Morocco
| | - Saadia Ba-M'hamed
- Laboratory of Pharmacology, Neurobiology, Anthropobiology, and Environment, Faculty of Sciences, Cadi Ayyad University, Marrakesh, Morocco
| | - Benjamin Lefranc
- Univ Rouen Normandie, INSERM, NorDiC, UMR 1239, Rouen, France; Institute for Research and Innovation in Biomedicine, Rouen, France
| | - Jérôme Leprince
- Univ Rouen Normandie, INSERM, NorDiC, UMR 1239, Rouen, France; Institute for Research and Innovation in Biomedicine, Rouen, France
| | - Loubna Boukhzar
- Laboratory of Pharmacology, Neurobiology, Anthropobiology, and Environment, Faculty of Sciences, Cadi Ayyad University, Marrakesh, Morocco; Univ Rouen Normandie, INSERM, NorDiC, UMR 1239, Rouen, France; Institute for Research and Innovation in Biomedicine, Rouen, France
| | - Youssef Anouar
- Univ Rouen Normandie, INSERM, NorDiC, UMR 1239, Rouen, France; Institute for Research and Innovation in Biomedicine, Rouen, France.
| | - Mohamed Bennis
- Laboratory of Pharmacology, Neurobiology, Anthropobiology, and Environment, Faculty of Sciences, Cadi Ayyad University, Marrakesh, Morocco
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Emery MA, Eitan S. Members of the same pharmacological family are not alike: Different opioids, different consequences, hope for the opioid crisis? Prog Neuropsychopharmacol Biol Psychiatry 2019; 92:428-449. [PMID: 30790677 DOI: 10.1016/j.pnpbp.2019.02.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 02/15/2019] [Accepted: 02/15/2019] [Indexed: 01/14/2023]
Abstract
Pain management is the specialized medical practice of modulating pain perception and thus easing the suffering and improving the life quality of individuals suffering from painful conditions. Since this requires the modulation of the activity of endogenous systems involved in pain perception, and given the large role that the opioidergic system plays in pain perception, opioids are currently the most effective pain treatment available and are likely to remain relevant for the foreseeable future. This contributes to the rise in opioid use, misuse, and overdose death, which is currently characterized by public health officials in the United States as an epidemic. Historically, the majority of preclinical rodent studies were focused on morphine. This has resulted in our understanding of opioids in general being highly biased by our knowledge of morphine specifically. However, recent in vitro studies suggest that direct extrapolation of research findings from morphine to other opioids is likely to be flawed. Notably, these studies suggest that different opioid analgesics (opioid agonists) engage different downstream signaling effects within the cell, despite binding to and activating the same receptors. This recognition implies that, in contrast to the historical status quo, different opioids cannot be made equivalent by merely dose adjustment. Notably, even at equianalgesic doses, different opioids could result in different beneficial and risk outcomes. In order to foster further translational research regarding drug-specific differences among opioids, here we review basic research elucidating differences among opioids in pharmacokinetics, pharmacodynamics, their capacity for second messenger pathway activation, and their interactions with the immune system and the dopamine D2 receptors.
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Affiliation(s)
- Michael A Emery
- Behavioral and Cellular Neuroscience, Department of Psychological and Brain Sciences, Texas A&M University, 4235 TAMU, College Station, TX 77843, USA; Interdisciplinary Program in Neuroscience, Texas A&M Institute for Neuroscience (TAMIN), College Station, TX, USA
| | - Shoshana Eitan
- Behavioral and Cellular Neuroscience, Department of Psychological and Brain Sciences, Texas A&M University, 4235 TAMU, College Station, TX 77843, USA; Interdisciplinary Program in Neuroscience, Texas A&M Institute for Neuroscience (TAMIN), College Station, TX, USA.
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3
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Mercado-Reyes J, Almanza A, Segura-Chama P, Pellicer F, Mercado F. D2-like receptor agonist synergizes the μ-opioid agonist spinal antinociception in nociceptive, inflammatory and neuropathic models of pain in the rat. Eur J Pharmacol 2019; 853:56-64. [PMID: 30876975 DOI: 10.1016/j.ejphar.2019.03.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 02/25/2019] [Accepted: 03/12/2019] [Indexed: 11/19/2022]
Abstract
Opioids are potent analgesic drugs, but their use has been limited due to their side effects. Antinociceptive effects of D2-like receptor agonists such as quinpirole have been shown at the spinal cord level; however, their efficacy is not as high as that of opioids. Dopaminergic agonists are long-prescribed and well-tolerated drugs that have been useful to treat clinically and experimentally painful conditions. Because current pain treatments are not completely effective, the aim of this work was to determine if a D2-like receptor agonist improves the antinociceptive effects of a μ-opioid receptor agonist. Drugs were intrathecally administered in adult rats; mechanonociceptive and thermonociceptive tests were carried out. Intraplantar injection of complete Freund's adjuvant (CFA) and sciatic loose ligation (SLL) were used for inflammatory and neuropathic models of pain, respectively. In intact animals, D-Ala2, N-MePhe4, Gly-ol-enkephalin (DAMGO; a µ-opioid receptor agonist) increased the paw withdrawal latencies (PWL) in thermal and mechanical nociceptive tests in a dose-dependent manner. Quinpirole (D2-like receptor agonist) increased PWL only in mechanonociception. In the presence of quinpirole (1 nmol), the ED50 of the mechanical antinociceptive effect of DAMGO was significantly decreased (8-fold). Coadministration of 1 nmol quinpirole and 30 pmol DAMGO completely reversed hyperalgesia in the CFA model, whereas 100 pmol DAMGO plus 1 nmol quinpirole reversed the allodynia in the SLL model. This work offers evidence about a synergistic antinociceptive effect between opioidergic and dopaminergic drugs. This combination may relieve painful conditions resistant to conventional treatments, and it may reduce the adverse effects of chronic opioid administration.
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Affiliation(s)
- Jonathan Mercado-Reyes
- Laboratorio de Fisiología Celular, Dirección de Investigaciones en Neurociencias. Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Ciudad de México, Mexico
| | - Angélica Almanza
- Laboratorio de Fisiología Celular, Dirección de Investigaciones en Neurociencias. Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Ciudad de México, Mexico
| | - Pedro Segura-Chama
- Laboratorio de Fisiología Celular, Dirección de Investigaciones en Neurociencias. Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Ciudad de México, Mexico; Cátedras CONACyT - Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Ciudad de México, Mexico
| | - Francisco Pellicer
- Laboratorio de Neurofisiología Integrativa, Dirección de Investigaciones en Neurociencias. Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Ciudad de México, Mexico
| | - Francisco Mercado
- Laboratorio de Fisiología Celular, Dirección de Investigaciones en Neurociencias. Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Ciudad de México, Mexico.
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Synaptic upregulation and superadditive interaction of dopamine D2- and μ-opioid receptors after peripheral nerve injury. Pain 2014; 155:2526-2533. [DOI: 10.1016/j.pain.2014.09.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 09/09/2014] [Accepted: 09/11/2014] [Indexed: 11/16/2022]
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Stolz ED, Viana AF, Hasse DR, von Poser GL, do Rego JC, Rates SMK. Uliginosin B presents antinociceptive effect mediated by dopaminergic and opioid systems in mice. Prog Neuropsychopharmacol Biol Psychiatry 2012; 39:80-7. [PMID: 22627196 DOI: 10.1016/j.pnpbp.2012.05.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 05/03/2012] [Accepted: 05/15/2012] [Indexed: 12/16/2022]
Abstract
Previous studies have shown that uliginosin B inhibits dopamine reuptake in rat brain. This compound occurs in Hypericum polyanthemum and H. caprifoliatum for which was reported to have antinociceptive effect sensitive to naloxone. The aim of this study was to assess the antinociceptive effect of uliginosin B and to evaluate the involvement of opioid and dopaminergic receptors activation. Uliginosin B presented antinociceptive effect in hot-plate and abdominal writhing tests, in mice, at doses that did not impair the motor coordination (15 mg/kg, i.p.). Uliginosin B in high dose (90 mg/kg, i.p.) presented ataxic effect in the rotarod apparatus. These effects seem to be mediated by distinct receptors since the effect on the hot-plate was completely abolished by naloxone and sulpiride, but it was unaffected by SCH 23390. On the other hand, the motor impairment induced by uliginosin B was completely prevented by naloxone and partially prevented by sulpiride and SCH 23390. However, the receptors' activation appears to be indirect since uliginosin B did not bind to opioid and dopaminergic receptors. Thus, uliginosin B effects probably are due to its ability to inhibit monoamine reuptake with consequent activation of dopamine receptors and indirect stimulation of opioid system.
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Affiliation(s)
- Eveline Dischkaln Stolz
- Programa de Pós-Graduação em Neurociências, Universidade Federal do Rio Grande do Sul, Avenida Ipiranga 2752/505c, 90610-000 Porto Alegre, RS, Brazil
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6
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Li T, Hou Y, Cao W, Yan CX, Chen T, Li SB. Role of dopamine D3 receptors in basal nociception regulation and in morphine-induced tolerance and withdrawal. Brain Res 2012; 1433:80-4. [DOI: 10.1016/j.brainres.2011.11.045] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Revised: 10/25/2011] [Accepted: 11/19/2011] [Indexed: 10/14/2022]
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7
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Hosseini M, Taiarani Z, Hadjzadeh MAR, Salehabadi S, Tehranipour M, Alaei HA. Different responses of nitric oxide synthase inhibition on morphine-induced antinociception in male and female rats. PATHOPHYSIOLOGY 2011; 18:143-9. [DOI: 10.1016/j.pathophys.2010.05.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2009] [Revised: 11/16/2009] [Accepted: 05/18/2010] [Indexed: 01/28/2023] Open
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Substance P1–7 induces antihyperalgesia in diabetic mice through a mechanism involving the naloxone-sensitive sigma receptors. Eur J Pharmacol 2010; 626:250-5. [DOI: 10.1016/j.ejphar.2009.10.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Revised: 09/19/2009] [Accepted: 10/06/2009] [Indexed: 11/24/2022]
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9
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Martin LJ, Persinger MA. The Influence of Various Pharmacological Agents on the Analgesia Induced by an Applied Complex Magnetic Field Treatment: A Receptor System Potpourri. Electromagn Biol Med 2009. [DOI: 10.1080/15368370500205431] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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10
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Mei J, Pasternak GW. Modulation of brainstem opiate analgesia in the rat by sigma 1 receptors: a microinjection study. J Pharmacol Exp Ther 2007; 322:1278-85. [PMID: 17545312 DOI: 10.1124/jpet.107.121137] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
sigma(1) Receptors have been implicated in the modulation of opioid analgesia. In the current study, we examined the role of sigma(1) systems in the periaqueductal gray (PAG), the rostroventral medulla (RVM), and the locus coeruleus (LC) of the rat, regions previously shown to be sensitive to morphine. Morphine was a potent analgesic in all three regions. Coadministration of the sigma(1) agonist (+)-pentazocine diminished the analgesic actions of morphine in all three regions, although the PAG was far less sensitive than the other two regions. Blockade of the sigma(1) receptors with haloperidol in the RVM markedly enhanced the analgesic actions of coadministered morphine, implying a tonic activity of the sigma(1) system in this region. This effect was mimicked by down-regulation of RVM sigma(1) receptors using an antisense approach. However, no tonic sigma(1) activity was observed in either the LC or the PAG. The RVM also was important in modulating analgesia elicited from morphine microinjected into the PAG. The analgesic actions of morphine given into the PAG could be attenuated by (+)-pentazocine placed into the RVM, whereas haloperidol in the RVM enhanced PAG morphine analgesia. These studies illustrate the pharmacological importance of sigma(1) receptors in the brainstem modulation of opioid analgesia.
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Affiliation(s)
- Jianfeng Mei
- The Laboratory of Molecular Neuropharmacology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 1002, USA
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11
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Pelissier T, Laurido C, Hernandez A, Constandil L, Eschalier A. Biphasic effect of apomorphine on rat nociception and effect of dopamine D2 receptor antagonists. Eur J Pharmacol 2006; 546:40-7. [PMID: 16905131 DOI: 10.1016/j.ejphar.2006.06.081] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2005] [Revised: 06/22/2006] [Accepted: 06/27/2006] [Indexed: 11/26/2022]
Abstract
Studies on the effect of dopaminergic agonists in behavioral measures of nociception have gathered numerous but rather conflicting data. We studied the effects of the D(1)/D(2) receptor agonist apomorphine, as well as the modulatory effects of (S)-(-)-sulpiride (selective D(2) receptor antagonist) and domperidone (peripheral D(2) receptor antagonist), on thermal, mechanical and chemical nociception on rats. Apomorphine induced a biphasic dose-response relationship, low doses producing hyperalgesia and high doses inducing antinociception. Tonic (chemical) pain was more sensitive to apomorphine than phasic (thermal and mechanical thresholds) pain. (S)-(-)-sulpiride, but not domperidone, fully antagonized the antinociceptive effect of apomorphine in all three measures of nociception, pointing to a participation of D(2) dopaminergic receptors for the antinociceptive action of apomorphine. Although spinal sites for dopaminergic ligands mechanistically may account for the effects observed, involvement of dopaminergic receptors of the forebrain could probably explain better the antinociceptive effects of apomorphine, especially in chemical tonic pain.
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Affiliation(s)
- Teresa Pelissier
- Programa de Biología Molecular y Clínica, Facultad de Medicina, Universidad de Chile, Chile.
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12
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Hayward MD, Low MJ. Naloxone's suppression of spontaneous and food-conditioned locomotor activity is diminished in mice lacking either the dopamine D(2) receptor or enkephalin. ACTA ACUST UNITED AC 2005; 140:91-8. [PMID: 16125819 DOI: 10.1016/j.molbrainres.2005.07.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Revised: 07/19/2005] [Accepted: 07/24/2005] [Indexed: 10/25/2022]
Abstract
Mice lacking the D2 dopamine receptor (D2(-/-)) and congenic to the C57BL/6J background were tested for opioid-mediated locomotor activity to examine the involvement of the D2 dopamine receptor in opioid pharmacology. Morphine-stimulated locomotor activity did not significantly differ between the two genotypes. The opioid antagonist naloxone dose-dependently decreased spontaneous motor activity in wild-type mice but was without significant effect in D2(-/-) mice. The magnitude of food-conditioned increases in locomotor activity in wild-type mice and D2(-/-) mice was similar but naloxone did not decrease conditioned motor activity in D2(-/-) mice. Spontaneous locomotor activity of mice lacking the endogenous opioids beta-endorphin and/or enkephalin was also tested and we found that naloxone did not reduce activity in mice specifically lacking enkephalin. We suggest that the D2 dopamine receptor is necessary for modulation of spontaneous locomotor activity stimulated by the endogenous opioid enkephalin.
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Affiliation(s)
- Michael D Hayward
- Vollum Institute L-474, Oregon Health and Science University, 3181 S.W. Sam Jackson Park Rd., Portland, OR 97239, USA.
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Weizman T, Pick CG, Backer MM, Rigai T, Bloch M, Schreiber S. The antinociceptive effect of amisulpride in mice is mediated through opioid mechanisms. Eur J Pharmacol 2004; 478:155-9. [PMID: 14575800 DOI: 10.1016/j.ejphar.2003.08.049] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Antinociceptive effects of various neuroleptics in animal acute pain-models have been described, mediated trough different pathways including the opioid system. In this study, we assessed the antinociceptive effects of the atypical neuroleptic drug amisulpride, which acts as a selective blocker of dopamine D2 and D3 receptors. Furthermore, at low doses amisulpride has a selective preference for presynaptic dopamine autoreceptors, while at high doses it manifests a preferential action at post-synaptic dopamine receptors. We found amisulpride to be a potent antinociceptor agent in the mouse tail-flick assay, with an ED50 of 36.6 mg/kg. This effect was antagonized by naloxone (P<0.05), indicating an involvement of opioid mechanisms as mediators of the antinociceptive effect of amisulpride. Beta-funaltrexamine (mu1- and mu2-opioid receptor antagonist), naloxonazine (selective mu1-opioid receptor antagonist), naltrindole (selective delta-opioid receptor antagonist), Nor-binaltorphamine (kappa1-opioid receptor antagonist) reversed amisulpride antinociception at the same dose that they antagonized morphine's antinociceptive effect (all P<0.005). We found that the sensitivity of amisulpride-induced antinociception is mediated through selective involvement of all three opioid receptor subtypes. Based on previous studies with risperidone, clozapine and olanzapine we tend to attribute this global interaction with the opioid system to amisulpride's action at the dopamine D2 receptor sites.
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Affiliation(s)
- Tal Weizman
- Department of Psychiatry, Tel Aviv Sourasky Medical Center and Tel-Aviv University Sackler School of Medicine, Tel Aviv 64239, Israel
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14
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Fontella FU, Nunes ML, Crema LM, Balk RS, Dalmaz C, Netto CA. Taste modulation of nociception differently affects chronically stressed rats. Physiol Behav 2004; 80:557-61. [PMID: 14741241 DOI: 10.1016/j.physbeh.2003.10.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Stress responses cover a wide range of physiological changes, including alterations in the perception of and response to pain. Animals submitted to repeated stress present altered nociception and this effect is part of this process of adaptation; in addition pleasant and unpleasant experiences with tastes and odors have been shown to affect distinct behavioral aspects, such as pain perception. The aim of the present study is to verify the responses of repeatedly stressed rats (1 h of daily immobilization during 40 days) to pleasant and unpleasant tastes on nociception, when compared to control animals. An increase in the tail-flick latency (TFL) was observed 5 min after exposure to a sweet taste in the control group, whereas no effect was observed in chronically stressed animals. When submitted to an unpleasant taste (5% acetic acid), the chronically stressed group presented an increase in TFL, whereas no effect was observed in the control group. In conclusion, chronically stressed animals present different nociceptive responses to sweet and acid tastes; although control animals suitably respond to a sweet stimulus, stressed animals seem to be more apt to react to the unpleasant stimulus.
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Affiliation(s)
- Fernanda Urruth Fontella
- Departamento de Fisiologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul (UFRGS), Rua Domingos Crescêncio 215/101, CEP 90650-090, Porto Alegre, RS, Brazil.
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15
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Rieck RW, Ansari MS, Whetsell WO, Deutch AY, Kessler RM. Distribution of dopamine D2-like receptors in the human thalamus: autoradiographic and PET studies. Neuropsychopharmacology 2004; 29:362-72. [PMID: 14627996 DOI: 10.1038/sj.npp.1300336] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The distribution of dopamine (DA) D(2)-like receptors in the human thalamus was studied using in vitro autoradiographic techniques and in vivo positron emission tomography in normal control subjects. [(125)I]Epidepride, which binds with high affinity to DA D(2) and D(3) receptors, was used in autoradiographic studies to determine the distribution and density of D(2)-like receptors, and the epidepride analogue [(18)F]fallypride positron was used for positron emission tomography studies to delineate D(2)-like receptors in vivo. Both approaches revealed a heterogeneous distribution of thalamic D(2/3) receptors, with relatively high densities in the intralaminar and midline thalamic nuclei, including the paraventricular, parataenial, paracentral, centrolateral, and centromedian/parafascicular nuclei. Moderate densities of D(2/3) sites were seen in the mediodorsal and anterior nuclei, while other thalamic nuclei expressed lower levels of D(2)-like receptors. Most thalamic nuclei that express high densities of D(2)-like receptors project to forebrain DA terminal fields, suggesting that both the thalamic neurons expressing D(2)-like receptors and the projection targets of these neurons are regulated by DA. Because the midline/intralaminar nuclei receive prominent projections from both the ascending reticular activating core and the hypothalamus, these thalamic nuclei may integrate activity conveying both interoceptive and exteroceptive information to telencephalic DA systems involved in reward and cognition.
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Affiliation(s)
- Richard W Rieck
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
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16
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Rutledge LP, Ngong JM, Kuperberg JM, Samaan SS, Soliman KFA, Kolta MG. Dopaminergic system modulation of nociceptive response in long-term diabetic rats. Pharmacol Biochem Behav 2002; 74:1-9. [PMID: 12376147 DOI: 10.1016/s0091-3057(02)00949-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The present study examines the effects of dopaminergic system modulation on nociceptive response time in male diabetic rats. In this study, diabetes was induced by streptozotocin (STZ, 45 mg/kg) in adult male Sprague-Dawley rats. Insulin replacement therapy was initiated 6 weeks after the induction of diabetes for one-half of the diabetic group (1.5-2.5 IU/12 h/rat) and was continued throughout the duration of the study (up to 14 weeks). After 6 weeks of daily insulin replacement therapy, eight rats from each experimental group (STZ-diabetic, STZ-diabetic+insulin and nondiabetic control) were injected with either bromocriptine (BROM, 3 mg/kg/12 h), haloperidol (HALO, 1.5 mg/kg/12 h) or vehicle. Nociceptive response was measured by the hot plate (HP) latency test before the induction of diabetes (baseline), every 3 weeks for the first 12 weeks and then on days 5, 9 and 14 of treatment with dopaminergic agents. Animals were sacrificed 3 or 4 days after the last HP test and the brain, blood, spinal cord (SC), pituitary and adrenal glands (AD) were dissected for Met-enkephalin (ME) assay. The results show that nociceptive response of untreated diabetic animals increased gradually and significantly over the duration of this study. Administration of BROM and HALO significantly decreased and increased the nociceptive response, respectively, in all groups. However, the response of the diabetic group was more pronounced than that of the other two groups, especially for those treated with BROM. Daily insulin administration normalized nociceptive response to that of the nondiabetic controls. Diabetic animals receiving insulin replacement+BROM also showed normalized nociceptive response while the diabetic animals+HALO did not. Moreover, the administration of HALO and BROM resulted in an increase and decrease ME concentrations, respectively, in most tissues and brain regions examined. The effect of these dopaminergic agents on ME levels was greater in brain regions and tissues of the diabetic rats than in the diabetic groups receiving vehicle or in the nondiabetic control receiving these two agents. These data suggest that diabetes alters the sensitivity of the dopaminergic receptors and that altered response of the dopaminergic system could be indirectly involved in the modulation of nociception in diabetic rats possibly through the enhancement and/or deactivation of the endogenous Met-enkephalinergic system.
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Affiliation(s)
- L P Rutledge
- College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL 32307, USA
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Saitoh A, Onodera K, Morita K, Sodeyama M, Kamei J. Prazosin inhibits spontaneous locomotor activity in diabetic mice. Pharmacol Biochem Behav 2002; 72:365-9. [PMID: 11900807 DOI: 10.1016/s0091-3057(01)00766-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We examined the effect of prazosin, a selective alpha1-adrenergic receptor antagonist, on the enhanced spontaneous locomotor activity in streptozotocin-induced diabetic mice. Spontaneous locomotor activity in diabetic mice was significantly greater than that in nondiabetic mice. Pretreatment with either intracerebroventricular (5, 10 nmol) or intraperitoneal (0.5, 1.0 mg/kg) injection of prazosin dose-dependently reduced the spontaneous locomotor activity in diabetic mice, but not in nondiabetic mice. Furthermore, the enhanced dopamine turnover ratio in the limbic forebrain in diabetic mice was reduced to the same level as that in nondiabetic mice after the administration of prazosin. Thus, these results suggest that alpha1-adrenergic receptors might play an important role in the enhanced spontaneous locomotor activity in diabetic mice. Furthermore, alpha1-adrenoceptor antagonism might have an inhibitory effect on presynaptic dopaminergic neurotransmission in the limbic forebrain in diabetic mice.
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Affiliation(s)
- Akiyoshi Saitoh
- Department of Pathophysiology and Therapeutics, Faculty of Pharmaceutical Sciences, Hoshi University, 4-41, Ebara 2-chome, Shinagawa-ku, Tokyo 142-8501, Japan
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Potentiation of opioid analgesia in dopamine2 receptor knock-out mice: evidence for a tonically active anti-opioid system. J Neurosci 2001. [PMID: 11567069 DOI: 10.1523/jneurosci.21-19-07788.2001] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Dopamine systems are intimately involved with opioid actions. Pharmacological studies suggest an important modulatory effect of dopamine and its receptors on opioid analgesia. We have now examined these interactions in a knock-out model in which the dopamine(2) (D(2)) receptor has been disrupted. Loss of D(2) receptors enhances, in a dose-dependent manner, the analgesic actions of the mu analgesic morphine, the kappa(1) agonist U50,488H and the kappa(3) analgesic naloxone benzoylhydrazone. The responses to the delta opioid analgesic [d-Pen(2),d-Pen(5)]enkephalin were unaffected in the knock-out animals. Loss of D(2) receptors also potentiated spinal orphanin FQ/nociceptin analgesia. Antisense studies using a probe targeting the D(2) receptor revealed results similar to those observed in the knock-out model. The modulatory actions of D(2) receptors were independent of final sigma receptor systems because the final sigma agonist (+)-pentazocine lowered opioid analgesia in all mice, including the D(2) knock-out group. Thus, dopamine D(2) receptors represent an additional, significant modulatory system that inhibits analgesic responses to mu and kappa opioids.
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