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Gopalsamy B, Chia JSM, Farouk AAO, Sulaiman MR, Perimal EK. Zerumbone-Induced Analgesia Modulated via Potassium Channels and Opioid Receptors in Chronic Constriction Injury-Induced Neuropathic Pain. Molecules 2020; 25:molecules25173880. [PMID: 32858809 PMCID: PMC7503342 DOI: 10.3390/molecules25173880] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/29/2020] [Accepted: 08/03/2020] [Indexed: 12/15/2022] Open
Abstract
Zerumbone, a monocyclic sesquiterpene from the wild ginger plant Zingiber zerumbet (L.) Smith, attenuates allodynia and hyperalgesia. Currently, its mechanisms of action in neuropathic pain conditions remain unclear. This study examines the involvement of potassium channels and opioid receptors in zerumbone-induced analgesia in a chronic constriction injury (CCI) neuropathic pain mice model. Male Institute of Cancer Research (ICR) mice were subjected to CCI and behavioral responses were tested on day 14. Responses toward mechanical allodynia and thermal hyperalgesia were tested with von Frey's filament and Hargreaves' tests, respectively. Symptoms of neuropathic pain were significantly alleviated following treatment with zerumbone (10 mg/kg; intraperitoneal, i.p.). However, when the voltage-dependent K+ channel blocker tetraethylammonium (TEA, 4 mg/kg; i.p.), ATP-sensitive K+ channel blocker, glibenclamide (GLIB, 10 mg/kg; i.p.); small-conductance Ca2+-activated K+ channel inhibitor apamin (APA, 0.04 mg/kg; i.p.), or large-conductance Ca2+-activated K+ channel inhibitor charybdotoxin (CHAR, 0.02 mg/kg; i.p.) was administered prior to zerumbone (10 mg/kg; i.p.), the antiallodynic and antihyperalgesic effects of zerumbone were significantly reversed. Additionally, non-specific opioid receptors antagonist, naloxone (NAL, 10 mg/kg; i.p.), selective µ-, δ- and κ-opioid receptor antagonists; β-funaltrexamine (β-FN, 40 mg/kg; i.p.), naltrindole (20 mg/kg; s.c.), nor-binaltorphamine (10 mg/kg; s.c.) respectively attenuated the antiallodynic and antihyperalgesic effects of zerumbone. This outcome clearly demonstrates the participation of potassium channels and opioid receptors in the antineuropathic properties of zerumbone. As various clinically used neuropathic pain drugs also share this similar mechanism, this compound is, therefore, a highly potential substitute to these therapeutic options.
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Affiliation(s)
- Banulata Gopalsamy
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia; (B.G.); (A.A.O.F.); (M.R.S.)
| | - Jasmine Siew Min Chia
- Centre for Community Health Studies, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur 50300, Malaysia;
| | - Ahmad Akira Omar Farouk
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia; (B.G.); (A.A.O.F.); (M.R.S.)
| | - Mohd Roslan Sulaiman
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia; (B.G.); (A.A.O.F.); (M.R.S.)
| | - Enoch Kumar Perimal
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia; (B.G.); (A.A.O.F.); (M.R.S.)
- Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, University of Adelaide, Adelaide 5000, Australia
- Correspondence: ; Tel./Fax: +61-603-8947-2774
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Affiliation(s)
- Marlene A Wilson
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States
- Columbia VA Health Care System, Columbia, SC, United States
| | - Alexander J McDonald
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States
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Carrero JP, Kaigler KF, Hartshorn GH, Fadel JR, Wilson MA. Mu opioid receptor regulation of glutamate efflux in the central amygdala in response to predator odor. Neurobiol Stress 2019; 11:100197. [PMID: 31832510 PMCID: PMC6888766 DOI: 10.1016/j.ynstr.2019.100197] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 09/23/2019] [Accepted: 10/09/2019] [Indexed: 12/24/2022] Open
Abstract
The amygdala plays an important role in the responses to predator threat. Glutamatergic processes in amygdala regulate the behavioral responses to predator stress, and we have found that exposure to ferret odor activates glutamatergic neurons of the basolateral amygdala [BLA] which are known to project to the central amygdala [CeA]. Therefore, we tested if predator stress would increase glutamate release in the rat CeA using in vivo microdialysis, while monitoring behavioral responses during a 1 h exposure to ferret odor. Since injections of mu opioid receptor [MOR] agonists and antagonists into the CeA modulate behavioral responses to predator odor, we locally infused the MOR agonist DAMGO or the MOR antagonist CTAP into the CeA during predator stress to examine effects on glutamate efflux and behavior. We found that ferret odor exposure increased glutamate, but not GABA, efflux in the CeA, and this effect was attenuated by tetrodotoxin. Interestingly, increases in glutamate efflux elicited by ferret odor exposure were blocked by infusion of CTAP, but CTAP did not alter the behavioral responses during predator stress. DAMGO alone enhanced glutamate efflux, but did not modulate glutamate efflux during predator stress. These studies demonstrate that ferret odor exposure, like other stressors, enhances glutamate efflux in the CeA. Further, they suggest that activation of MOR in the CeA may help shape the defensive response to predator odor and other threats. Predator odor stress increased glutamate efflux in the central amygdala. Predator stress-induced increases in glutamate were blocked by a mu opioid receptor antagonist. Blocking glutamate efflux in the amygdala did not alter behavioral responses to predator odor. Infusion of a mu opioid receptor agonist also increased glutamate efflux in the central amygdala.
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Affiliation(s)
- Jeffrey Parrilla Carrero
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, 29208, USA.,Columbia VA Health Care System, Columbia, SC, 29209, USA
| | - Kris F Kaigler
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, 29208, USA.,Columbia VA Health Care System, Columbia, SC, 29209, USA
| | - George H Hartshorn
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, 29208, USA.,Columbia VA Health Care System, Columbia, SC, 29209, USA
| | - Jim R Fadel
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, 29208, USA.,Columbia VA Health Care System, Columbia, SC, 29209, USA
| | - Marlene A Wilson
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, 29208, USA.,Columbia VA Health Care System, Columbia, SC, 29209, USA
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Lucot JB. Effects of naloxone on motion sickness in cats alone and with broad spectrum antiemetics. Auton Neurosci 2016; 202:97-101. [PMID: 27615675 DOI: 10.1016/j.autneu.2016.08.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 08/25/2016] [Accepted: 08/29/2016] [Indexed: 11/18/2022]
Abstract
Doses of naloxone far below those which elicit emesis increase the sensitivity to motion sickness. In order to evaluate the possible interaction with broad spectrum antiemetics, low doses of naloxone were tested alone and in combination with 8-hydroxy-2-(di-n-propylamine)tetralin (DPAT), fentanyl and the NK1 antagonist CP-99994. A modified autonomic symptom rating scale was unaffected by any drug and thus considered of little value. Fentanyl and NK1 antagonists decreased the duration of the retch/vomit sequence. Naloxone alone and in combination with each of the drugs increased the duration of retching/vomiting. Naloxone also increased the number of vomiting sequences. The results are interpreted in terms of possible site(s) of action of the antiemetic drugs.
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Affiliation(s)
- James B Lucot
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University, Dayton, OH, United States.
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Differential effects of naloxone on rewarding electrical stimulation of the central nucleus of the amygdala and parabrachial complex in a place preference study. Brain Res Bull 2016; 124:182-9. [PMID: 27173444 DOI: 10.1016/j.brainresbull.2016.04.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 04/11/2016] [Accepted: 04/28/2016] [Indexed: 12/29/2022]
Abstract
The central nucleus of the amygdala (CeA) is considered to be involved in different affective, sensory, regulatory, and acquisition processes. This study analyzed whether electrical stimulation of the PB-CeA system induces preferences in a concurrent place preference (cPP) task, as observed after stimulation of the parabrachial-insular cortex (PB-IC) axis. It also examined whether the rewarding effects are naloxone-dependent. The results show that electrical stimulation of the CeA and external lateral parabrachial subnucleus (LPBe) induces consistent preference behaviors in a cPP task. However, subcutaneous administration of an opiate antagonist (naloxone; 4mg/ml/kg) blocked the rewarding effect of the parabrachial stimulation but not that of the amygdala stimulation. These results are interpreted in the context of multiple brain reward systems that appear to differ both anatomically and neurochemically, notably with respect to the opiate system.
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NMDA and dopamine D1 receptors within NAc-shell regulate IEG proteins expression in reward circuit during cocaine memory reconsolidation. Neuroscience 2015; 315:45-69. [PMID: 26674058 DOI: 10.1016/j.neuroscience.2015.11.063] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 11/03/2015] [Accepted: 11/29/2015] [Indexed: 01/11/2023]
Abstract
Reactivation of consolidated memory initiates a memory reconsolidation process, during which the reactivated memory is susceptible to strengthening, weakening or updating. Therefore, effective interference with the memory reconsolidation process is expected to be an important treatment for drug addiction. The nucleus accumbens (NAc) has been well recognized as a pathway component that can prevent drug relapse, although the mechanism underlying this function is poorly understood. We aimed to clarify the regulatory role of the NAc in the cocaine memory reconsolidation process, by examining the effect of applying different pharmacological interventions to the NAc on Zif 268 and Fos B expression in the entire reward circuit after cocaine memory reactivation. Through the cocaine-induced conditioned place preference (CPP) model, immunohistochemical and immunofluorescence staining for Zif 268 and Fos B were used to explore the functional activated brain nuclei after cocaine memory reactivation. Our results showed that the expression of Zif 268 and Fos B was commonly increased in the medial prefrontal cortex (mPFC), the infralimbic cortex (IL), the NAc-core, the NAc-shell, the hippocampus (CA1, CA2, and CA3 subregions), the amygdala, the ventral tegmental area (VTA), and the supramammillary nucleus (SuM) following memory reconsolidation, and Zif 268/Fos B co-expression was commonly observed (for Zif 268: 51-68%; for Fos B: 52-66%). Further, bilateral NAc-shell infusion of MK 801 and SCH 23390, but not raclopride or propranolol, prior to addictive memory reconsolidation, decreased Zif 268 and Fos B expression in the entire reward circuit, except for the amygdala, and effectively disturbed subsequent CPP-related behavior. In summary, N-methyl-d-aspartate (NMDA) and dopamine D1 receptors, but not dopamine D2 or β adrenergic receptors, within the NAc-shell, may regulate Zif 268 and Fos B expression in most brain nuclei of the reward circuit after cocaine memory reactivation. These findings indicated that the NAc played a key role in regulating addictive memory reconsolidation by influencing the function of the entire addictive memory network.
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Glial activation and midkine and pleiotrophin transcription in the ventral tegmental area are modulated by morphine administration. J Neuroimmunol 2014; 274:244-8. [PMID: 25108770 DOI: 10.1016/j.jneuroim.2014.07.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 07/19/2014] [Accepted: 07/23/2014] [Indexed: 12/23/2022]
Abstract
Opiates cause persistent restructuring in the mesolimbic reward system. Although a possible role for midkine and pleiotrophin cytokines in the field of synaptic plasticity has been proposed, it has not been assessed whether morphine administration regulates astrogliosis and midkine and pleiotrophin transcription. We observed that single morphine injection and chronic morphine increased glial fibrillary acidic protein expression in the ventral tegmental area (VTA). Interestingly, single morphine injection and chronic morphine increased VTA midkine and pleiotrophin mRNA expression. Given these results, we hypothesize a role for these cytokines in mediating, at least in part, acute neuroprotective effects and chronic neurotrophic adaptations that contribute to drug dependence.
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8
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Swimming improves the emotional memory deficit by scopolamine via mu opioid receptors. Physiol Behav 2014; 128:237-46. [DOI: 10.1016/j.physbeh.2014.02.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 09/29/2013] [Accepted: 02/04/2014] [Indexed: 11/23/2022]
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9
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Pedrón VT, Taravini IR, Induni AS, Balerio GN. Baclofen did not modify sexually dimorphic c-Fos expression during morphine withdrawal syndrome. Synapse 2012; 67:118-26. [DOI: 10.1002/syn.21620] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 10/26/2012] [Indexed: 12/18/2022]
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Bajo M, Roberto M, Madamba SG, Siggins GR. Neuroadaptation of GABAergic transmission in the central amygdala during chronic morphine treatment. Addict Biol 2011; 16:551-64. [PMID: 21182569 PMCID: PMC3117063 DOI: 10.1111/j.1369-1600.2010.00269.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
We investigated possible alterations of pharmacologically-isolated, evoked GABA(A) inhibitory postsynaptic potentials (eIPSPs) and miniature GABA(A) inhibitory postsynaptic currents (mIPSCs) in the rat central amygdala (CeA) elicited by acute application of µ-opioid receptor (MOR) agonists (DAMGO and morphine; 1 µM) and by chronic morphine treatment with morphine pellets. The acute activation of MORs decreased the amplitudes of eIPSPs, increased paired-pulse facilitation (PPF) of eIPSPs and decreased the frequency (but not the amplitude) of mIPSCs in a majority of CeA neurons, suggesting that acute MOR-dependent modulation of this GABAergic transmission is mediated predominantly via presynaptic inhibition of GABA release. We observed no significant changes in the membrane properties, eIPSPs, PPF or mIPSCs of CeA neurons during chronic morphine treatment compared to CeA of naïve or sham rats. Superfusion of the MOR antagonist CTOP (1 µM) increased the mean amplitude of eIPSPs in a majority of CeA neurons to the same degree in both naïve/sham and morphine-treated rats, suggesting a tonic activation of MORs in both conditions. Superfusion of DAMGO decreased eIPSP amplitudes and the frequency of mIPSCs equally in both naïve/sham and morphine-treated rats but decreased the amplitude of mIPSCs only in morphine treated rats, an apparent postsynaptic action. Our combined findings suggest the development of tolerance of the CeA GABAergic system to inhibitory effects of acute activation of MORs on presynaptic GABA release and possible alteration of MOR-dependent postsynaptic mechanisms that may represent important neuroadaptations of the GABAergic and MOR systems during chronic morphine treatment.
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MESH Headings
- Amygdala/drug effects
- Amygdala/physiology
- Analgesics, Opioid/pharmacology
- Animals
- Drug Tolerance
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Inhibitory Postsynaptic Potentials/drug effects
- Inhibitory Postsynaptic Potentials/physiology
- Male
- Miniature Postsynaptic Potentials/drug effects
- Miniature Postsynaptic Potentials/physiology
- Morphine/pharmacology
- Narcotics/pharmacology
- Neurons/drug effects
- Neurons/physiology
- Patch-Clamp Techniques
- Rats
- Rats, Sprague-Dawley
- Receptors, GABA-A/drug effects
- Receptors, GABA-A/physiology
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/physiology
- Somatostatin/analogs & derivatives
- Somatostatin/pharmacology
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
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Affiliation(s)
- Michal Bajo
- Molecular and Integrative Neurosciences Department, The Scripps Research Institute, La Jolla, California, USA
| | - Marisa Roberto
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, California, USA
| | - Samuel G. Madamba
- Molecular and Integrative Neurosciences Department, The Scripps Research Institute, La Jolla, California, USA
| | - George Robert Siggins
- Molecular and Integrative Neurosciences Department, The Scripps Research Institute, La Jolla, California, USA
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Extracellular signal-regulated kinase activation in the amygdala mediates elevated plus maze behavior during opioid withdrawal. Behav Pharmacol 2011; 20:576-83. [PMID: 19738463 DOI: 10.1097/fbp.0b013e32832ec57e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This study examined whether activation of extracellular signal-regulated kinase (ERK) contributes to the increased open-arm time observed in the elevated plus maze (EPM) during opioid withdrawal. We applied SL327, a selective ERK kinase (MEK) inhibitor, to specific limbic areas and examined the effect on EPM behaviors of controls and during naloxone-precipitated morphine withdrawal. We next confirmed that ERK activation increased in limbic areas of mice undergoing naloxone-precipitated morphine withdrawal. Direct injection of SL327 into the amygdala blocked the withdrawal-induced increase in open-arm time; however, injecting SL327 into the septum had no effect. Consistent with these results, both 0.2 and 2 mg/kg naloxone increased ERK activation in the central amygdala of morphine-dependent mice. In drug-naive mice, 2 mg/kg naloxone, but not 0.2 mg/kg, increased ERK activation in the central amygdala. During withdrawal, increased ERK activation was also observed in the lateral septum. In the locus coeruleus, a significant increase was observed only in morphine-dependent mice receiving 2 mg/kg, but not 0.2 mg/kg naloxone. In conclusion, ERK activation in limbic areas is likely involved in both the aversive properties of naloxone and in the affective/emotional symptoms of opioid withdrawal, including mediating EPM behaviors.
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Differential respiratory control of the upper airway and diaphragm muscles induced by 5-HT1A receptor ligands. Sleep Breath 2011; 16:135-47. [PMID: 21221824 DOI: 10.1007/s11325-010-0466-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 10/29/2010] [Accepted: 12/21/2010] [Indexed: 12/18/2022]
Abstract
BACKGROUND Serotonin (5-HT) has a role in respiratory function and dysfunction. Although 5-HT affects respiratory drive to both phrenic and cranial motoneurons, relatively little is known about the role of 5-HT receptor subtypes in the control of upper airway muscle (UAM) respiratory activity. MATERIALS AND METHODS Here, we performed central injections of 5-HT1A agonist (8-OHDPAT) or antagonist (WAY100635) in anesthetized rats and analyzed changes in the electromyographic activity of several UAM and other cardiorespiratory parameters. We also compared the pattern of Fos expression induced after central injection of a control solution or 8-OHDPAT. RESULTS Results showed that 8-OHDPAT induced a robust increase in UAM activity, associated with either tachypnea under volatile anesthesia or bradypnea under liquid anesthesia. Injection of WAY100635 switched off UAM respiratory activity and led to bradypnea, suggesting a tonic excitatory role of endogenous 5-HT1A receptor activation. Co-injection of the agonist and the antagonist blocked the effects produced by each drug alone. Besides drug-induced changes in respiratory frequency, only slight increases in surface of diaphragm bursts were observed. Significant increases in Fos expression after 5-HT1A receptor activation were seen in the nucleus tractus solitarius, nucleus raphe pallidus, parapyramidal region, retrotrapezoid nucleus, lateral parabrachial, and Kölliker-Fuse nuclei. This restricted pattern of Fos expression likely identified the neural substrate responsible for the enhancement of UAM respiratory activity observed after 8-OHDPAT injection. CONCLUSIONS These findings suggest an important role for the 5-HT1A receptors in the neural control of upper airway patency and may be relevant to counteract pharyngeal atonia during obstructive sleep apneas.
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Hjornevik T, Schoultz BW, Marton J, Gjerstad J, Drzezga A, Henriksen G, Willoch F. Spinal long-term potentiation is associated with reduced opioid neurotransmission in the rat brain. Clin Physiol Funct Imaging 2010; 30:285-93. [PMID: 20662879 DOI: 10.1111/j.1475-097x.2010.00939.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
INTRODUCTION Neuronal events leading to development of long-term potentiation (LTP) in the nociceptive pathways may be a cellular mechanism underlying hyperalgesia. In the present study, we examine if induction of spinal LTP may be associated with functional changes in the supraspinal opioidergic system. The opioid receptors (ORs) play a key role in nociceptive processing and controlling the descending modulatory system to the spinal cord. METHODS Spinal LTP was induced by electrical high-frequency stimulation (HFS) conditioning applied to the sciatic nerve, and the excitability at spinal level was verified by spinal field potential recordings. To study supraspinal changes in opioid neurotransmission following the same HFS conditioning, we used small animal positron emission tomography (PET) and [(11)C]Phenethyl-Orvinol ([(11)C]PEO). All rats included in the PET study were scanned at baseline and 150 min after HFS, and specific binding was calculated with a reference tissue model. RESULTS A clear C-fibre LTP, i.e. increased C-fibre response and reduced C-fibre threshold, was observed 150 min after HFS conditioning (t-test, P<0.05, n = 6). Moreover, increased OR binding, relative to baseline, was observed after the same type of HFS conditioning ipsilaterally in the amygdala, hippocampus, somatosensory cortex and superior colliculus, and bilaterally in the nucleus accumbens, caudate putamen and hypothalamus (paired t-test, HFS>baseline, P<0.05, n = 8). CONCLUSIONS HFS conditioning of the sciatic nerve resulted in both spinal LTP and functional changes in supraspinal opioidergic signalling. Our findings suggest that induction of spinal LTP may be associated with reduced opioid neurotransmission in brain regions involved in pain modulation and affective-emotional responses.
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Affiliation(s)
- Trine Hjornevik
- Centre for Molecular Biology and Neuroscience & Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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14
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Kang-Park MH, Kieffer BL, Roberts AJ, Roberto M, Madamba SG, Siggins GR, Moore SD. Mu-opioid receptors selectively regulate basal inhibitory transmission in the central amygdala: lack of ethanol interactions. J Pharmacol Exp Ther 2008; 328:284-93. [PMID: 18854491 DOI: 10.1124/jpet.108.140749] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Endogenous opioid systems are implicated in the actions of ethanol. For example, mu-opioid receptor (MOR) knockout (KO) mice self-administer less alcohol than the genetically intact counterpart wild-type (WT) mice (Roberts et al., 2000). MOR KO mice also exhibit less anxiety-like behavior than WT mice (Filliol et al., 2000). To investigate the neurobiological mechanisms underlying these behaviors, we examined the effect of ethanol in brain slices from MOR KO and WT mice using sharp-electrode and whole-cell patch recording techniques. We focused our study in the central nucleus of the amygdala (CeA) because it is implicated in alcohol drinking behavior and stress behavior. We found that the amplitudes of evoked inhibitory postsynaptic currents (IPSCs) or inhibitory postsynaptic potentials (IPSPs) were significantly greater in MOR KO mice than WT mice. In addition, the baseline frequencies of spontaneous and miniature GABA(A) receptor-mediated inhibitory postsynaptic currents were significantly greater in CeA neurons from MOR KO than WT mice. However, ethanol enhancements of evoked IPSP and IPSC amplitudes and the frequency of miniature IPSCs were comparable between WT and MOR KO mice. Baseline spontaneous and miniature excitatory postsynaptic currents (EPSCs) and ethanol effects on EPSCs were not significantly different between MOR KO and WT mice. Based on knowledge of CeA circuitry and projections, we hypothesize that the role of MOR- and GABA receptor-mediated mechanisms in CeA underlying reinforcing effects of ethanol operate independently, possibly through pathway-specific responses within CeA.
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Affiliation(s)
- Maeng-Hee Kang-Park
- Department of Psychiatry, Duke University Medical Center, Durham, North Carolina, USA
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15
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Lindholm J, Guitart-Masip M, Hassankhali H, Landgren S, Nicoleau C, Giménez-Llort L, Terenius L, Ogren SO, Johansson B. Effects of naltrexone and acamprosate on alcohol-induced NGFI-A expression in mouse brain. Neurochem Res 2008; 33:2062-9. [PMID: 18427989 DOI: 10.1007/s11064-008-9687-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2007] [Accepted: 03/25/2008] [Indexed: 10/22/2022]
Abstract
In search for the substrate of naltrexone and acamprosate action on alcohol craving, we investigated the effects of ethanol alone and combined with naltrexone or acamprosate on expression of nerve growth factor-inducible clone A (NGFI-A; zif268). In Experiments 1 and 3, alcohol (2 g/kg) alone or in combination with naltrexone (15 mg/kg) or acamprosate (300 mg/kg) was injected intraperitoneally into mice. In Experiment 2, treatment was nor-BNI (0.5 mg/kg) to investigate whether the effect of naltrexone involved blockade of kappa-opioid receptors. Both ethanol and naltrexone alone induced NGFI-A in the central amygdala, but not in several other areas; these effects were additive. However, acamprosate alone or in combination with ethanol had no effect on NGFI-A mRNA, while nor-BNI induced NGFI-A mRNA in the basolateral amygdala. The central amygdala appears to be an important target of both alcohol and naltrexone. Acamprosate may not share the site of action with naltrexone despite being used for the same therapeutic purpose.
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Affiliation(s)
- Jeanette Lindholm
- Department of Clinical Neuroscience, Karolinska Institutet, Karolinska University Hospital Solna, Stockholm, Sweden
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16
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Lucas M, Frenois F, Vouillac C, Stinus L, Cador M, Le Moine C. Reactivity and plasticity in the amygdala nuclei during opiate withdrawal conditioning: differential expression of c-fos and arc immediate early genes. Neuroscience 2008; 154:1021-33. [PMID: 18501523 DOI: 10.1016/j.neuroscience.2008.04.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2007] [Revised: 03/14/2008] [Accepted: 04/04/2008] [Indexed: 11/27/2022]
Abstract
Opiate withdrawal leads to the emergence of an aversive state that can be conditioned to a specific environment. Reactivation of these withdrawal memories has been suggested to be involved in relapse to drug-seeking of abstinent opiate addicts. Among the limbic areas that are likely to mediate these features of opiate dependence, amygdala nuclei represent critical neural substrates. Using a conditioned place aversion paradigm (CPA), we have previously shown specific opposite patterns of reactivity in the basolateral (BLA) and the central (CeA) amygdala, when comparing the experience of acute opiate withdrawal with the re-exposure to a withdrawal-paired environment. These data gave clues about the potential mechanisms by which amygdala nuclei may be involved in withdrawal memories. To extend these results, the present study aimed to assess the cellular reactivity and plasticity of amygdala nuclei during the opiate withdrawal conditioning process. For this, we have quantified c-fos and arc expression using in situ hybridization in rats, following each of the three conditioning sessions during CPA, and after re-exposure to the withdrawal-paired environment. BLA output neurons showed an increase in the expression of the plasticity-related arc gene during conditioning that was also increased by re-exposure to the withdrawal-paired environment. Interestingly, the CeA showed an opposite pattern of responding, and the intercalated cell masses (ITC), a possible inhibitory interface between the BLA and CeA, showed a persistent activation of c-fos and arc mRNA. We report here specific c-fos and arc patterns of reactivity in amygdala nuclei during withdrawal conditioning. These findings improve our understanding of the involvement of the amygdala network in the formation and retrieval of withdrawal memories. Plasticity processes within BLA output neurons during conditioning, may participate in increasing the BLA reactivity to conditioned stimuli, which could in turn (by the control of downstream nuclei) reinforce and drive the motivational properties of withdrawal over drug consumption.
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Affiliation(s)
- M Lucas
- Université Victor Segalen Bordeaux 2, Université Bordeaux 1, CNRS UMR 5227, Team "Neuropsychopharmacology of Addiction," 146 bis rue Léo Saignat, 33076 Bordeaux, France
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17
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Hamlin AS, McNally GP, Osborne PB. Induction of c-Fos and zif268 in the nociceptive amygdala parallel abstinence hyperalgesia in rats briefly exposed to morphine. Neuropharmacology 2007; 53:330-43. [PMID: 17631915 DOI: 10.1016/j.neuropharm.2007.05.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2006] [Revised: 04/25/2007] [Accepted: 05/21/2007] [Indexed: 02/06/2023]
Abstract
Opioid-induced analgesia can be followed by spontaneous pain in humans, and hyperalgesia in rodents. In this study, opioid-induced hyperalgesia was measured by the tail-flick test when acute abstinence was precipitated by administering naloxone to drug naive rats that had experienced morphine analgesia for only 30 min. In a further experiment, the drug treatment that previously caused opioid-induced hyperalgesia was found to increase neurons expressing nuclear c-Fos or zif268 proteins in extended amygdalar regions targeted by projections of the ascending spino-parabrachio-amygdaloid nociceptive pathway. Transcription factor induction, however, was not detected in multiple brain regions known to respond in parallel with the same extended amygdalar structures when (1) rats are exposed to interoceptive/physical stressors, or (2) naloxone is used to precipitate abstinence in opioid dependent rats. Surprisingly, in many regions c-Fos induction by morphine was reduced or blocked by naloxone, even though these subjects had also experienced the effects of morphine for 30 min prior to antagonist administration. It is suggested transcription factor induction during opioid hyperalgesia in non-dependent rats could support the induction or consolidation of neural plasticity in nociceptive amygdaloid circuitry previously suggested to function in bi-directional control of pain and expression of pain-related behaviors.
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Affiliation(s)
- Adam S Hamlin
- Pain Management Research Institute (Kolling Institute), The University of Sydney at the Royal North Shore Hospital, St Leonards, NSW 2065, Australia
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18
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Scott DJ, Domino EF, Heitzeg MM, Koeppe RA, Ni L, Guthrie S, Zubieta JK. Smoking modulation of mu-opioid and dopamine D2 receptor-mediated neurotransmission in humans. Neuropsychopharmacology 2007; 32:450-7. [PMID: 17091130 DOI: 10.1038/sj.npp.1301238] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This is a pilot examination of the hypothesis that some of the effects of smoking cigarettes in humans are mediated through nicotine activation of opioid and dopamine (DA) neurotransmission. Neuroimaging was performed using positron emission tomography and the radiotracers [11C]carfentanil and [11C]raclopride, labeling mu-opioid and DA D2 receptors, respectively. Six healthy male smokers were abstinent overnight. After radiotracer administration, subjects smoked two denicotinized cigarettes, followed 45 min later by two average nicotine cigarettes. Dynamic data were acquired over 90 min, and transformed into parametric maps of receptor availability in vivo (binding potential, BP), corresponding to low and high nicotine smoking periods and analyzed on a voxel-by-voxel basis using SPM'99 and correction for multiple comparisons. Significant activation of mu-opioid receptor-mediated neurotransmission from denicotinized to average nicotine conditions was observed in the right anterior cingulate cortex. DA D2 neurotransmission was activated in the ventral basal ganglia, correlating with Fagerström scale nicotine dependence scores. Lower mu-opioid receptor BP was also detected during the denicotinized smoking condition in the smoker group, compared to baseline scans in non-smokers, in the cingulate cortex, thalamus, ventral basal ganglia, and amygdala. These reductions were reversed during the average nicotine condition in the thalamus, ventral basal ganglia and amygdala. These data point to both the feasibility of simultaneously examining opioid and DA neurotransmission responses to smoking in humans, as well as to the need to examine non-nicotine aspects of smoking to more fully understand the behavioral effects of this drug.
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Affiliation(s)
- David J Scott
- Department of Psychiatry, Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI 48109-0720, USA
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19
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Chieng BCH, Christie MJ, Osborne PB. Characterization of neurons in the rat central nucleus of the amygdala: cellular physiology, morphology, and opioid sensitivity. J Comp Neurol 2006; 497:910-27. [PMID: 16802333 DOI: 10.1002/cne.21025] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The central nucleus of the amygdala (CeA) orchestrates autonomic and other behavioral and physiological responses to conditioned stimuli that are aversive or elicit fear. As a related CeA function is the expression of hypoalgesia induced by conditioned stimuli or systemic morphine administration, we examined postsynaptic opioid modulation of neurons in each major CeA subdivision. Following electrophysiological recording, biocytin-filled neurons were precisely located in CeA regions identified by chemoarchitecture (enkephalin-immunoreactivity) and cytoarchitecture (DAPI nuclear staining) in fixed adult rat brain slices. This revealed a striking distribution of physiological types, as 92% of neurons in capsular CeA were classified as late-firing, whereas no neurons in the medial CeA were of this class. In contrast, 60% or more of neurons in the lateral and medial CeA were low-threshold bursting neurons. Mu-opioid receptor (MOPR) agonists induced postsynaptic inhibitory potassium currents in 61% of CeA cells, and this ratio was maintained in each subdivision and for each physiological class of neuron. However, MOPR agonists more frequently inhibited bipolar/fusiform cells than triangular or multipolar neurons. A subpopulation of MOPR-expressing neurons were also inhibited by delta opioid receptor agonists, whereas a separate population were inhibited kappa opioid receptors (KOPR). The MOPR agonist DAMGO inhibited 9/9 CeM neurons with projections to the parabrachial nucleus identified by retrograde tracer injection. These data support models of striatopallidal organization that have identified striatal-like and pallidal-like CeA regions. Opioids can directly inhibit output from each subdivision by activating postsynaptic MOPRs or KOPRs on distinct subpopulations of opioid-sensitive neurons.
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Affiliation(s)
- Billy C H Chieng
- Pain Management Research Institute, University of Sydney at Royal North Shore Hospital, NSW 2065, Australia
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20
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Glass MJ, Kruzich PJ, Colago EEO, Kreek MJ, Pickel VM. Increased AMPA GluR1 receptor subunit labeling on the plasma membrane of dendrites in the basolateral amygdala of rats self-administering morphine. Synapse 2006; 58:1-12. [PMID: 16037950 DOI: 10.1002/syn.20176] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Glutamate-dependent synaptic plasticity is emerging as an important neural substrate of addiction. These drug-dependent neural adaptations may occur within brain systems that mediate reward, emotion, and cognitive function such as the amygdala complex. Modification of glutamate receptor targeting may be a key mechanism mediating neural plasticity; however, evidence for alteration of amygdala AMPA receptor localization in response to drug self-administration is lacking. High-resolution immunogold electron microscopic immunocytochemistry was used to compare surface and intracellular labeling of the calcium sensitive AMPA GluR1 receptor subunit in the basolateral (BLA) and central (CeA) nuclei of the amygdala in rats self-administering escalating doses of morphine or saline. Morphine self-administration was associated with regionally diverse effects on dendritic GluR1 targeting in the BLA and CeA. In the BLA of morphine self-administering animals, there was a significant increase in the proportion of immunogold particles for GluR1 on the plasma membrane of dendrites, particularly in association with extrasynaptic sites, which was most prominent in large (2-4 microm) profiles. In contrast, there were no significant differences in surface or intracellular immunogold labeling in the CeA between morphine self-administering and control animals. In both amygdala regions, GluR1 and the micro-opioid receptor, the major cellular target of morphine, were only infrequently colocalized. These results indicate that GluR1 targeting is a dynamic process that can be differentially affected in distinct amygdala regions in response to chronic self-administration of morphine. Homeostatic adaptations in the subcellular localization of calcium sensitive AMPA receptors within the BLA may be an important neural substrate for alterations in reward, autonomic function, and behavioral processes associated with opiate addiction.
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Affiliation(s)
- Michael J Glass
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, New York 10021, USA
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21
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Smith YR, Stohler CS, Nichols TE, Bueller JA, Koeppe RA, Zubieta JK. Pronociceptive and antinociceptive effects of estradiol through endogenous opioid neurotransmission in women. J Neurosci 2006; 26:5777-85. [PMID: 16723535 PMCID: PMC1808228 DOI: 10.1523/jneurosci.5223-05.2006] [Citation(s) in RCA: 223] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Prominent interindividual and sex-dependent differences have been described in responses to sustained pain and other stressful stimuli. Variations in mu-opioid receptor-mediated endogenous opioid neurotransmission may underlie some of these processes. We examined both baseline mu-opioid receptor levels and the activation of this neurotransmitter system during sustained pain using positron emission tomography in a sample of young healthy men and women. Women were studied twice, during low and high estrogen states. The high-estrogen state was associated with regional increases in baseline mu-opioid receptor availability in vivo and a greater activation of endogenous opioid neurotransmission during the pain stressor. The latter did not differ from that obtained in males. During the low estrogen condition, however, significant reductions in endogenous opioid tone were observed at the level of thalamus, nucleus accumbens, and amygdala, which were associated with hyperalgesic responses. Estrogen-associated variations in the activity of mu-opioid neurotransmission correlated with individual ratings of the sensory and affective perceptions of the pain and the subsequent recall of that experience. These data demonstrate a significant role of estrogen in modulating endogenous opioid neurotransmission and associated psychophysical responses to a pain stressor in humans.
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22
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Moyse E, Bauer S, Charrier C, Coronas V, Krantic S, Jean A. Neurogenesis and neural stem cells in the dorsal vagal complex of adult rat brain: New vistas about autonomic regulations—a review. Auton Neurosci 2006; 126-127:50-8. [PMID: 16697711 DOI: 10.1016/j.autneu.2006.03.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2006] [Revised: 03/14/2006] [Accepted: 03/28/2006] [Indexed: 12/16/2022]
Abstract
The dorsal vagal complex (DVC) of the brainstem is the major reflex center of autonomic nervous system. Several neuroplasticity effectors have been identified in the DVC of adult rat, such as PSA-NCAM, GAP-43, BDNF and its receptor TrkB; moreover, acute vagal stimulation was found to induce c-fos and to down-regulate western-blot-assayed tissular concentration of PSA-NCAM. Adult neurogenesis was first shown in rat DVC by BrdU incorporation combined with phenotypic labelling in situ; new neurons are generated in equal proportions with new astrocytes and at a lower rate than in olfactory bulb or hippocampus. Intrinsic proliferative cells were then detected within the DVC of adult rat by means of Ki-67 immunohistochemistry and western-blot of D-cyclins. The presence of neural stem cells within DVC was directly demonstrated by applying the in vitro neurosphere assay on microdissected adult DVC explants; DVC-derived neurospheres display lower proliferation rate and neurogenic potential than forebrain ones. Vagotomy in adult promotes massive and transient increase of neurogenic and microglial proliferations within DVC, the kinetics and location of which were analyzed by Ki-67 immunohistochemistry and cyclin D western blot. These mechanisms shed light on so far unknown plasticity potential in DVC, which brings novel cues about physiological adaptations of autonomic reflexes in adult mammals.
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Affiliation(s)
- Emmanuel Moyse
- Lab. Physiologie Neurovégétative, UMR 6153 CNRS / 1147 INRA, Université Paul Cézanne-Aix-Marseille-3, Ave. Escadrille Normandie-Niemen, 13397 Marseille Cedex 20, France.
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23
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Ribeiro SC, Kennedy SE, Smith YR, Stohler CS, Zubieta JK. Interface of physical and emotional stress regulation through the endogenous opioid system and mu-opioid receptors. Prog Neuropsychopharmacol Biol Psychiatry 2005; 29:1264-80. [PMID: 16256255 DOI: 10.1016/j.pnpbp.2005.08.011] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/26/2005] [Indexed: 12/30/2022]
Abstract
Unraveling the pathways and neurobiological mechanisms that underlie the regulation of physical and emotional stress responses in humans is of critical importance to understand vulnerability and resiliency factors to the development of a number of complex physical and psychopathological states. Dysregulation of central stress response circuits have been implicated in the establishment of conditions as diverse as persistent pain, mood and personality disorders and substance abuse and dependence. The present review examines the contribution of the endogenous opioid system and mu-opioid receptors to the modulation and adaptation of the organism to challenges, such as sustained pain and negative emotional states, which threaten its internal homeostasis. Data accumulated in animal models, and more recently in humans, point to this neurotransmitter system as a critical modulator of the transition from acute (warning signals) to sustained (stressor) environmental adversity. The existence of pathways and regulatory mechanisms common to the regulation of both physical and emotional states transcend classical categorical disease classifications, and point to the need to utilize dimensional, "symptom"-related approximations to their study. Possible future areas of study at the interface of "mind" (cognitive-emotional) and "body" (physical) functions are delineated in this context.
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Affiliation(s)
- Saulo C Ribeiro
- University of Michigan, Department of Psychiatry and Molecular and Behavioral Neuroscience Institute, MBNI, 205 Zine Pitcher Place, 48109-0720, USA
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24
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Frenois F, Stinus L, Di Blasi F, Cador M, Le Moine C. A specific limbic circuit underlies opiate withdrawal memories. J Neurosci 2005; 25:1366-74. [PMID: 15703390 PMCID: PMC6725999 DOI: 10.1523/jneurosci.3090-04.2005] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2003] [Revised: 12/10/2004] [Accepted: 12/10/2004] [Indexed: 11/21/2022] Open
Abstract
Compulsive drug-seeking behavior and its renewal in former drug addicts is promoted by several situations, among which reactivation of drug withdrawal memories plays a crucial role. A neural hypothesis is that such memories reactivate the circuits involved in withdrawal itself and promote a motivational state leading to drug seeking or taking. To test this hypothesis, we have analyzed the neural circuits and cell populations recruited when opiate-dependent rats are reexposed to stimuli previously paired with withdrawal (memory retrieval) and compared them with those underlying acute withdrawal during conditioning (memory formation). Using in situ hybridization for c-fos expression, we report here that reexposure to a withdrawal-paired environment induced conditioned c-fos responses in a specific limbic circuit, which can be partially dissociated from the structures involved in acute withdrawal. At the amygdala level, c-fos responses were doubly dissociated between the central and basolateral (BLA) nuclei, when comparing the two situations. Detailed phenotypical analyses in the amygdala and ventral tegmental area (VTA) show that specific subpopulations in the BLA are differentially involved in the formation and retrieval of withdrawal memories, and strikingly that a population of VTA dopamine neurons is activated in both situations. Together, this indicates that withdrawal memories can drive activity changes in specific neuronal populations of interconnected limbic areas known to be involved in aversive motivational processes. This first study on the neural substrates of withdrawal memories strongly supports an incentive-motivational view of withdrawal in opiate addiction that could be crucial in compulsive drug seeking and relapse.
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Affiliation(s)
- François Frenois
- Centre National de la Recherche Scientifique Unité Mixte de Recherche 5541 Interactions Neuronales et Comportements, Université Victor Segalen Bordeaux 2, 33076 Bordeaux cedex, France
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25
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Levine AS, Olszewski PK, Mullett MA, Pomonis JD, Grace MK, Kotz CM, Billington CJ. Intra-amygdalar injection of DAMGO: effects on c-Fos levels in brain sites associated with feeding behavior. Brain Res 2004; 1015:9-14. [PMID: 15223361 DOI: 10.1016/j.brainres.2004.04.039] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/01/2004] [Indexed: 11/20/2022]
Abstract
It is well known that the mu opioid agonist, Tyr-D-Ala-Gly-(me) Phe-Gly-ol (DAMGO), increases food intake in rats when injected into a variety of brain sites including the central nucleus of the amygdala (CeA). Immunohistochemical studies measuring c-Fos immunoreactivity (IR) suggest that the CeA contributes to opioid-related feeding. In the current study, we injected 2 nmol of DAMGO and measured food intake, c-Fos IR levels in various brain sites involved in feeding behavior, and mu opioid receptor internalization. We also studied the effect of CeA-injected DAMGO on LiCl-induced increases in c-Fos IR in the amygdala. As was expected, intra-CeA injection of DAMGO increased food intake of rats over a 4-h period. DAMGO injection into the CeA also resulted in mu opioid receptor internalization in the CeA, indicating activation of mu opioid receptor expressing neurons in this site. Administration of DAMGO into the CeA increased c-Fos IR levels in the shell of the nucleus accumbens (NAcc), but not in 17 other brain sites that were studied. We also found that intra-CeA injection of DAMGO, prior to LiCl injection, decreased c-Fos IR levels in the CeA compared to vehicle-injected rats. Thus, intra-CeA administration of DAMGO may increase feeding, in part, by activating neurons in the shell of the nucleus accumbens and by inhibiting activity of selected neurons in the CeA.
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Affiliation(s)
- Allen S Levine
- Minnesota Obesity Center, Minneapolis Veterans Affairs Medical Center and University of Minnesota, Research Service (151), One Veterans Drive, Minneapolis, MN 55417, USA.
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26
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Pan WX, McNaughton N. The supramammillary area: its organization, functions and relationship to the hippocampus. Prog Neurobiol 2004; 74:127-66. [PMID: 15556285 DOI: 10.1016/j.pneurobio.2004.09.003] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2004] [Accepted: 09/15/2004] [Indexed: 11/18/2022]
Abstract
The supramammillary area of the hypothalamus, although small in size, can have profound modulatory effects on the hippocampal formation and related temporal cortex. It can control hippocampal plasticity and also has recently been shown to contain cells that determine the frequency of hippocampal rhythmical slow activity (theta rhythm). We review here its organization and anatomical connections providing an atlas and a new nomenclature. We then review its functions particularly in relation to its links with the hippocampus. Much of its control of behaviour and its differential activation by specific classes of stimuli is consistent with a tight relationship with the hippocampus. However, its ascending connections involve not only caudal areas of the cortex with close links to the hippocampus but also reciprocal connections with more rostral areas such as the infralimbic and anterior cingulate cortices. These latter areas appear to be the most rostral part of a network that, via the medial septum, hippocampus and lateral septum, is topographically mapped into the hypothalamus. The supramammillary area is thus diffusely connected with areas that control emotion and cognition and receives more topographically specific return information from areas that control cognition while also receiving ascending information from brain stem areas involved in emotion. We suggest that it is a key part of a network that recursively transforms information to achieve integration of cognitive and emotional aspects of goal-directed behaviour.
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Affiliation(s)
- Wei-Xing Pan
- Department of Physiology and Center for Neuroscience, University of Otago, POB56, Dunedin, New Zealand
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27
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Roda F, Pio J, Bianchi AL, Gestreau C. Effects of anesthetics on hypoglossal nerve discharge and c-Fos expression in brainstem hypoglossal premotor neurons. J Comp Neurol 2004; 468:571-86. [PMID: 14689487 DOI: 10.1002/cne.10974] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
This study examined the effects of anesthesia on the hypoglossal nerve and diaphragm activities and on c-Fos expression in brainstem hypoglossal premotor neurons (pmXII). Experiments were performed in 71 rats by using halothane inhalation, pentobarbital sodium, or mixtures of alpha-chloralose and urethane or ketamine and xylazine. First, various cardiorespiratory parameters were measured in the rats (n = 31) during both awake and anesthetized conditions. The volatile anesthetic halothane, but not the other anesthetics, was always associated with a strong phasic inspiratory activity in the hypoglossal nerve. Second, a double-immunohistochemical study was performed in awake and anesthetized rats (n = 40) to gauge the level of activity of pmXII neurons. Brainstem pmXII neurons were identified after microiontophoresis of the retrograde tracer Fluoro-Gold in the right hypoglossal motor nucleus. Patterns of c-Fos expression at different brainstem levels were compared in five groups of rats (i.e., awake or anesthetized with halothane, pentobarbital, chloralose-urethane, and ketamine-xylazine). Sections were processed for double detection of c-Fos protein and Fluoro-Gold by using the standard ABC method and a two-color peroxidase technique. Anesthesia with halothane induced the strongest c-Fos expression in a restricted pool of pmXII located in the pons at the level of the Kölliker-Fuse nucleus and the intertrigeminal region. The results demonstrated a major effect of halothane in inducing changes in hypoglossal activity and revealed a differential expression of c-Fos protein in pmXII neurons among groups of anesthetized rats. We suggest that halothane mediates changes in respiratory hypoglossal nerve discharge by altering activity of premotor neurons in the Kölliker-Fuse and intertrigeminal region.
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Affiliation(s)
- Fabrice Roda
- Laboratoire de Physiologie Neurovégétative, UMR Centre National de la Recherche Scientifique 6153, Institut National de la Recherche Agronomique 1147, Faculté des Sciences et Techniques Saint Jérôme, 13397 Marseille 20, France
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28
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Lee MH, Kim H, Lim BV, Chang HK, Lee TH, Jang MH, Shin MC, Lee J, Shin MS, Kim CJ. Naloxone potentiates treadmill running-induced increase in c-Fos expression in rat hippocampus. Life Sci 2003; 73:3139-47. [PMID: 14550853 DOI: 10.1016/j.lfs.2003.06.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The expression of c-Fos is induced by a variety of stimuli and is sometimes used as a marker for increased neuronal activity. In the present study, the effect of treadmill running on c-Fos expression in the hippocampus and the involvement of opioid receptors were investigated via c-Fos immunohistochemistry. It was shown that c-Fos expression in the CA1 region, the CA2 and CA3 regions, and the dentate gyrus of the hippocampus was significantly increased by treadmill running and naloxone, a nonselective opioid receptors antagonist, treatment enhanced treadmill exercise-induced increase of hippocampal c-Fos expression. Base on the present results, it can be suggested that treadmill running increases hippocampal neuronal activity and that endogenous opioids curtail the exercise-induced increase.
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Affiliation(s)
- Myoung-Hwa Lee
- Research Institute of Sports Science, Korea University, #1 5-ga Anam-dong, Sungbuk-gu, Seoul 136-701, South Korea
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29
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Trang T, Sutak M, Quirion R, Jhamandas K. Spinal administration of lipoxygenase inhibitors suppresses behavioural and neurochemical manifestations of naloxone-precipitated opioid withdrawal. Br J Pharmacol 2003; 140:295-304. [PMID: 12970109 PMCID: PMC1574036 DOI: 10.1038/sj.bjp.0705440] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. This study investigated the role of spinal lipoxygenase (LOX) products in the induction and expression of opioid physical dependence using behavioural assessment of withdrawal and immunostaining for CGRP and Fos protein expression in the spinal cord. 2. Administration of escalating doses (5-50 mg kg-1; i.p.) of morphine for 5 days markedly elevated CGRP-like immunoreactivity in the dorsal horn of the rat spinal cord. Naloxone (2 mg kg-1; i.p.) challenge precipitated a robust withdrawal syndrome that depleted CGRP-like immunoreactivity and increased the number of Fos-like immunoreactive neurons in the dorsal horn. 3. Intrathecal administration of NDGA (10, 20 microg), a nonselective LOX inhibitor, AA-861 (1.5, 3 microg), a 5-LOX selective inhibitor, or baicalein (1.4, 2.8 microg), a 12-LOX selective inhibitor, concurrently with systemic morphine for 5 days or as a single injection immediately preceding naloxone challenge, blocked the depletion of CGRP-like immunoreactivity, prevented increase in the number of Fos-like immunoreactive neurons in the dorsal horn, and significantly attenuated the morphine withdrawal syndrome. 4. The results of this study suggest that activity of LOX products, at the spinal level, contributes to the expression of opioid physical dependence, and that this activity may be expressed through increased sensory neuropeptide release.
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Affiliation(s)
- Tuan Trang
- Department of Pharmacology and Toxicology, Faculty of Health Sciences, Queen's University, 523 Botterell Hall, Kingston, Ont., Canada K7L 3N6
| | - Maaja Sutak
- Department of Pharmacology and Toxicology, Faculty of Health Sciences, Queen's University, 523 Botterell Hall, Kingston, Ont., Canada K7L 3N6
| | - Remi Quirion
- Douglas Hospital Research Centre and Department of Psychiatry, McGill University, Montreal, Que., Canada H9 H 1R3
| | - Khem Jhamandas
- Department of Pharmacology and Toxicology, Faculty of Health Sciences, Queen's University, 523 Botterell Hall, Kingston, Ont., Canada K7L 3N6
- Author for correspondence:
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30
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Veinante P, Stoeckel ME, Lasbennes F, Freund-Mercier MJ. c-Fos and peptide immunoreactivities in the central extended amygdala of morphine-dependent rats after naloxone-precipitated withdrawal. Eur J Neurosci 2003; 18:1295-305. [PMID: 12956728 DOI: 10.1046/j.1460-9568.2003.02837.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The central extended amygdala, a forebrain macrostructure, may represent a common substrate for acute drug reward and the dysphoric effects of drug withdrawal. To test its involvement during opiate withdrawal, we studied the distribution of c-Fos immunoreactive neurons, in relation to their neuropeptide content, in brain sections from morphine-dependent or naive rats, killed 90 min after naloxone or saline intraperitoneal injection. Naloxone treatment in naive rats induced a slight increase in c-Fos immunoreactivity in the central amygdaloid nucleus, the lateral bed nucleus of the stria terminalis and the interstitial nucleus of the posterior limb of the anterior commissure. In morphine-dependent rats, naloxone injection significantly increased the number of c-Fos-positive neurons in these structures as well as in the majority of the other central extended amygdala components. Double immunocytochemistry was used to determine the neurochemical nature of c-Fos-positive neurons in the central extended amygdala. Corticotropin-releasing factor- and methionine-enkephakin-immunoreactive neurons displayed c-Fos immunoreactivity in naive rats after naloxone injection, whereas only enkephalinergic neurons were found to be c-Fos positive in morphine-dependent rats after naloxone injection. The possible involvement of the corticotropin-releasing factor system during withdrawal is discussed. These results suggest that the whole central extended amygdala is activated during opiate withdrawal, with a lateral to medial decreasing gradient, and emphasize the role of peptidergic systems in this morphofunctional continuum.
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Affiliation(s)
- Pierre Veinante
- UMR 7519, CNRS/Université Louis Pasteur, 21 rue René Descartes, 67084 Strasbourg, France.
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Le Guen S, Gestreau C, Besson JM. Morphine withdrawal precipitated by specific mu, delta or kappa opioid receptor antagonists: a c-Fos protein study in the rat central nervous system. Eur J Neurosci 2003; 17:2425-37. [PMID: 12814374 DOI: 10.1046/j.1460-9568.2003.02678.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have recently shown concurrent changes in behavioural responses and c-Fos protein expression in the central nervous system in both naive and morphine-dependent rats after systemic administration of the opioid antagonist naloxone. However, because naloxone acts on the three major types of opioid receptors, the present study aimed at determining, in the same animals, both changes in behaviour and c-Fos-like immunoreactivity after intravenous injection of selective opioid antagonists, such as mu (beta-funaltrexamine, 10 mg/kg), delta (naltrindole, 4 mg/kg) or kappa (nor-binaltorphimine, 5 mg/kg) opioid receptor antagonists, in naive or morphine-dependent rats. In a first experimental series, only beta-funaltrexamine increased c-Fos expression in the eight central nervous system structures examined, whereas no effect was seen after naltrindole or nor-binaltorphimine administration in naive rats. These results suggest a tonic activity in the endogenous opioid peptides acting on mu opioid receptors in normal rats. A second experimental series in morphine-dependent rats showed that beta-funaltrexamine had the highest potency in the induction of classical signs of morphine withdrawal syndrome, as well as the increase in c-Fos expression in the 22 central nervous system structures studied, suggesting a major role of mu opioid receptors in opioid dependence. However, our results also demonstrated that naltrindole and, to a lesser extent, nor-binaltorphimine were able to induce moderate signs of morphine withdrawal and relatively weak c-Fos protein expression in restricted central nervous system structures. Therefore, delta and kappa opioid receptors may also contribute slightly to opioid dependence.
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Affiliation(s)
- Stéphanie Le Guen
- Laboratoire de Physiopharmacologie du Système Nerveux, Institut National de la Santé et de la Recherche Médicale (INSERM) and Ecole Pratique des Hautes Etudes (EPHE), Paris, France.
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Milanés MV, Laorden ML, Angel E, Tankosic P, Burlet A. Effect of naloxone-precipitated morphine withdrawal on CRH and vasopressin mRNA expression in the rat hypothalamic paraventricular nucleus. Neurosci Lett 2002; 334:58-62. [PMID: 12431775 DOI: 10.1016/s0304-3940(02)01036-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Morphine withdrawal is characterized by an increase in the hypothalamus-pituitary-adrenocortical (HPA) axis activity. Here, by means of in situ hybridization, the changes in CRH and vasopressin (AVP) mRNAs have been analysed within the rat hypothalamic paraventricular nucleus (PVN) during morphine dependence and after naloxone-precipitated morphine withdrawal. CRH and AVP mRNA expression were analysed 30 min following administration of saline or naloxone to control groups and to morphine dependent rats. The data for in situ hybridization analysis of PVN neurons show that there were no changes in the total size of labelled area for CRH or AVP mRNA during morphine withdrawal, indicating that dependence on morphine does not involve alterations in the number of neurons expressing CRH or AVP mRNA. However, levels of mRNA encoding for CRH were decreased in the PVN during morphine dependence and withdrawal. By contrast, injection of saline or naloxone to morphine dependent rats did not affect the intensity of AVM mRNA expression. All these findings are discussed in term of cellular events that couple morphine dependence-increased HPA axis activity with changes in gene expression in selective neurons of the PVN.
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Affiliation(s)
- M V Milanés
- Department of Pharmacology, University School of Medicine, Murcia, Spain.
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Frenois F, Cador M, Caillé S, Stinus L, Le Moine C. Neural correlates of the motivational and somatic components of naloxone-precipitated morphine withdrawal. Eur J Neurosci 2002; 16:1377-89. [PMID: 12405997 DOI: 10.1046/j.1460-9568.2002.02187.x] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In morphine-dependent rats, low naloxone doses have been shown to induce conditioned place aversion, which reflects the negative motivational component of opiate withdrawal. In contrast, higher naloxone doses are able to induce a 'full' withdrawal syndrome, including overt somatic signs. The c-fos gene is commonly used as a marker of neuronal reactivity to map the neural substrates that are recruited by various stimuli. Using in situ hybridization, we have analysed in the brain of morphine-dependent rats the effects of acute withdrawal syndrome precipitated by increasing naloxone doses on c-fos mRNA expression. Morphine dependence was induced by subcutaneous implantation of slow-release morphine pellets for 6 days and withdrawal was precipitated by increasing naloxone doses inducing the motivational (7.5 and 15 micro g/kg) and somatic (30 and 120 micro g/kg) components of withdrawal. Our mapping study revealed a dissociation between a set of brain structures (extended amygdala, lateral septal nucleus, basolateral amygdala and field CA1 of the hippocampus) which exhibited c-fos mRNA dose-dependent variations from the lowest naloxone doses, and many other structures (dopaminergic and noradrenergic nuclei, motor striatal areas, hypothalamic nuclei and periaqueductal grey) which were less sensitive and recruited only by the higher doses. In addition, we found opposite dose-dependent variations of c-fos gene expression within the central (increase) and the basolateral (decrease) amygdala after acute morphine withdrawal. Altogether, these results emphasize that limbic structures of the extended amygdala along with the lateral septal nucleus, the basolateral amygdala and CA1 could specifically mediate the negative motivational component of opiate withdrawal.
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Affiliation(s)
- François Frenois
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5541 Interactions Neuronales et Comportements, BP28, Université Victor Segalen, Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux cedex, France.
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Moss IR, Laferrière A. Central neuropeptide systems and respiratory control during development. Respir Physiol Neurobiol 2002; 131:15-27. [PMID: 12106992 DOI: 10.1016/s1569-9048(02)00034-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The substance P/neurotachykinin-1 (NK-1) and the mu-opioid G protein-coupled receptor systems endow brainstem respiratory regions and display discrete developmental patterns. Hypoxia-induced neuropeptide release may increase receptor endocytosis, reducing receptor accessibility to ligands. We wondered whether the attenuated respiratory response to hypoxia of developing piglets after single (Respir. Physiol. 92 (1993a) 115) or repeated daily hypoxic exposure (J. Appl. Physiol. 83 (1997) 522) is influenced by differential endocytosis of NK-1 vs mu-opioid receptors. Whereas the long-term (24 h) response of both receptors to recurrent hypoxia in piglet brainstem is similar, i.e. upregulation, the short-term (5 min) response to single or recurrent hypoxia, albeit in rats, is different: radiolabelled NK-1 receptors are greatly reduced, suggesting enhanced endocytosis, but mu-opioid receptors remain unchanged, implying unaltered endocytosis. If confirmed in piglet brainstem, this difference would produce relatively more available mu-opioid receptors to opioid peptides in hypoxia that might contribute to the attenuated respiratory responses to single and repeated hypoxia during development.
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Affiliation(s)
- Immanuela Ravé Moss
- Developmental Respiratory Laboratory, The Research Institute of the McGill University Health Centre, The Montreal Children's Hospital, Room A-707, 2300 Tupper Street, Montreal, Que., Canada H3H 1P3.
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Abstract
This paper is the twenty-third installment of the annual review of research concerning the opiate system. It summarizes papers published during 2000 that studied the behavioral effects of the opiate peptides and antagonists, excluding the purely analgesic effects, although stress-induced analgesia is included. The specific topics covered this year include stress; tolerance and dependence; learning, memory, and reward; eating and drinking; alcohol and other drugs of abuse; sexual activity, pregnancy, and development; mental illness and mood; seizures and other neurological disorders; electrical-related activity; general activity and locomotion; gastrointestinal, renal, and hepatic function; cardiovascular responses; respiration and thermoregulation; and immunological responses.
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Affiliation(s)
- A L Vaccarino
- Department of Psychology, University of New Orleans, New Orleans, LA 70148, USA.
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Hamlin A, Buller KM, Day TA, Osborne PB. Peripheral withdrawal recruits distinct central nuclei in morphine-dependent rats. Neuropharmacology 2001; 41:574-81. [PMID: 11587712 DOI: 10.1016/s0028-3908(01)00101-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
This study examined if brain pathways in morphine-dependent rats are activated by opioid withdrawal precipitated outside the central nervous system. Withdrawal precipitated with a peripherally acting quaternary opioid antagonist (naloxone methiodide) increased Fos expression but caused a more restricted pattern of neuronal activation than systemic withdrawal (precipitated with naloxone which enters the brain). There was no effect on locus coeruleus and significantly smaller increases in Fos neurons were produced in most other areas. However in the ventrolateral medulla (A1/C1 catecholamine neurons), nucleus of the solitary tract (A2/C2 catecholamine neurons), lateral parabrachial nucleus, supramamillary nucleus, bed nucleus of the stria terminalis, accumbens core and medial prefrontal cortex no differences in the withdrawal treatments were detected. We have shown that peripheral opioid withdrawal can affect central nervous system pathways.
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Affiliation(s)
- A Hamlin
- Department of Physiology and Pharmacology, The University of Queensland, Qld 4072, Brisbane, Australia
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Lee SD, Magalang UJ, Krasney JA, Farkas GA. Opioidergic modulation of ventilatory response to sustained hypoxia in obese Zucker rats. OBESITY RESEARCH 2001; 9:407-13. [PMID: 11445663 DOI: 10.1038/oby.2001.53] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE To determine whether altered central and/or peripheral opioidergic mechanisms contribute to the altered ventilatory response to sustained hypoxia in obese Zucker rats. RESEARCH METHODS AND PROCEDURES Eight lean (176 +/- 8 [SEM] g) and eight obese (225 +/- 12 g) Zucker rats were studied at 6 weeks of age. Pulmonary ventilation ((E)), tidal volume (V(T)), and breathing frequency (f) at rest and in response to sustained (30 minutes) hypoxic (10% O(2)) challenges were measured on three separate occasions by the barometric method after the randomized, blinded administration of equal volumes of saline (control), naloxone methiodide (N(M); 5 mg/kg, peripheral opioid antagonist), or naloxone hydrochloride (N(HCl); 5 mg/kg, peripheral and central opioid antagonist). RESULTS Administration of N(M) and N(HCl) in lean animals had no effect on (E) either at rest or during 30 minutes of sustained exposure to hypoxia. Similarly, N(M) failed to alter (E) in obese rats. In contrast, N(HCl) significantly (p < 0.05) increased (E) and V(T) both at rest and during 2 to 10 minutes of hypoxic exposure in obese rats. After 20 to 30 minutes of hypoxic exposure, V(T) remained elevated with N(HCl), but the earlier elevation of (E) seemed to be attenuated due to a decrease in f at 20 minutes of exposure to hypoxia. DISCUSSION Thus, endogenous opioids modulate both resting (E) and the ventilatory response to sustained hypoxia in obese, but not in lean, Zucker rats by acting specifically on opioid receptors located within the central nervous system.
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Affiliation(s)
- S D Lee
- Department of Physical Therapy, Exercise and Nutrition Sciences, University at Buffalo, The State University of New York, Buffalo, New York 14214-3079, USA
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Le Guen S, Gestreau C, Besson JM. Sensitivity to naloxone of the behavioral signs of morphine withdrawal and c-Fos expression in the rat CNS: a quantitative dose-response analysis. J Comp Neurol 2001; 433:272-96. [PMID: 11283964 DOI: 10.1002/cne.1140] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Several studies have used c-Fos expression to delineate the neural substrate underlying naloxone-precipitated morphine withdrawal (MW). However, because behavioral manifestations of MW depend on both the degree of dependence and the doses of naloxone (NAL), a comprehensive study would require examining c-Fos expression in relation with the degree of MW. Here, changes in behavior and in c-Fos-like immunoreactivity (FLI) were studied in the same rats after injection of three doses of NAL to precipitate various degrees of MW. Fifteen established signs of MW were examined for 1 hour after NAL injection, and FLI was quantified in 52 regions of the brain and in the lumbosacral spinal cord. Linear regression analyses were used to examine changes in numbers of signs and FLI neurons with the doses of NAL, and data were considered dose-related for a statistical level of significance of P < 0.05. In summary, autonomic signs of MW increased in a dose-related manner, whereas somatomotor signs did not. After MW, 33 central nervous system regions exhibited significant increases in FLI and were, thus, considered as important neural correlates of MW. Twenty of them displayed dose-related increases in c-Fos expression and correspond to regions related to autonomic functions. Low c-Fos expression was detected in some regions involved in motor control or in reward, suggesting either their minor role in MW or a limitation of the technique. This dose-response analysis suggests that the increase in the severity of autonomic manifestations of MW is associated with a gradual activation of major structures of the autonomic nervous system.
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Affiliation(s)
- S Le Guen
- INSERM U161 and EPHE, 75014 Paris, France.
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