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Differential Effects of a Novel Opioid Ligand UTA1003 on Antinociceptive Tolerance and Motor Behaviour. Pharmaceuticals (Basel) 2022; 15:ph15070789. [PMID: 35890089 PMCID: PMC9318816 DOI: 10.3390/ph15070789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 06/18/2022] [Accepted: 06/21/2022] [Indexed: 02/05/2023] Open
Abstract
Analgesic tolerance is a major problem in the clinic for the maintenance of opioid-induced long-term pain relief. Opioids with mixed activity on multiple opioid receptors promise reduced antinociceptive tolerance in preclinical studies, but these compounds typically show poor bioavailability upon oral, subcutaneous, intraperitoneal, or intravenous administration. We designed UTA1003 as a novel opioid that acts as a mu (MOP) and kappa (KOP) opioid receptor agonist and a partial agonist for delta (DOP) opioid receptor. In the present study, its antinociceptive effects, as well as its effects on antinociceptive tolerance and motor behaviour, were investigated in male rats. Acute antinociception was measured before (basal) and at different time points after subcutaneous injection of UTA1003 or morphine using the tail flick and hot plate assays. Various motor behavioural activities, including horizontal locomotion, rearing, and turning, were automatically measured in an open-field arena. The antinociceptive and behavioural effects of repeated administration of UTA1003 and morphine were determined over eight days. UTA1003 induced mild antinociceptive effects after acute administration but induced no tolerance after repeated treatment. Importantly, UTA1003 co-treatment with morphine prevented antinociceptive tolerance compared to morphine alone. UTA1003 showed less motor suppression than morphine in both acute and sub-chronic treatment regimens, while it did not affect morphine-induced motor suppression or hyper-excitation. Based on these activities, we speculate that UTA1003 crosses the blood-brain barrier after subcutaneous administration and, therefore, could be developed as a lead molecule to avoid opioid-induced antinociceptive tolerance and motor suppression. Further structural modifications to improve its antinociceptive effects, toxicity profile, and ADME parameters are nevertheless required.
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Nakhjiri E, Roqanian S, Zangbar HS, Seyedi Vafaee M, Mohammadnejad D, Ahmadian S, Zamanzadeh S, Ehsani E, Shahabi P, Shahpasand K. Spinal Cord Injury Causes Prominent Tau Pathology Associated with Brain Post-Injury Sequela. Mol Neurobiol 2022; 59:4197-4208. [PMID: 35501632 DOI: 10.1007/s12035-022-02843-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 04/20/2022] [Indexed: 12/14/2022]
Abstract
Spinal cord injury (SCI) can result in significant neurological impairment and functional and cognitive deficits. It is well established that SCI results in focal neurodegeneration that gradually spreads to other cord areas. On the other hand, traumatic brain injury (TBI) is strongly associated with tau protein pathology and neurodegeneration that can spread in areas throughout the brain. Tau is a microtubule-associated protein abundant in neurons and whose abnormalities result in neuronal cell death. While SCI and TBI have been extensively studied, there is limited research on the relationship between SCI and brain tau pathology. As a result, in this study, we examined tau pathology in spinal cord and brain samples obtained from severe SCI mouse models at various time points. The effects of severe SCI on locomotor function, spatial memory, anxiety/risk-taking behavior were investigated. Immunostaining and immunoblotting confirmed a progressive increase in tau pathology in the spinal cord and brain areas. Moreover, we used electron microscopy to examine brain samples and observed disrupted mitochondria and microtubule structure following SCI. SCI resulted in motor dysfunction, memory impairment, and abnormal risk-taking behavior. Notably, eliminating pathogenic cis P-tau via systemic administration of appropriate monoclonal antibodies restored SCI's pathological and functional consequences. Thus, our findings suggest that SCI causes severe tauopathy that spreads to brain areas, indicating brain dysfunction. Additionally, tau immunotherapy with an anti-cis P-tau antibody could suppress pathogenic outcomes in SCI mouse models, with significant clinical implications for SCI patients. SCI induces profound pathogenic cis p-tau, which diffuses into the brain through CSF, resulting in brain neurodegeneration and cognitive decline.
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Affiliation(s)
- Elnaz Nakhjiri
- Neurosciences Research Center (NSRC), Tabriz University of Medical Sciences, Tabriz, Iran
| | - Shaqayeq Roqanian
- Department of Brain and Cognitive Sciences, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
| | - Hamid Soltani Zangbar
- Department of Neuroscience and Cognition, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | | | | | - Shahin Ahmadian
- Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | - Selva Zamanzadeh
- Department of Biological Sciences, Islamic Azad University, Tehran, Iran
| | - Ehsan Ehsani
- Department of Biology, Roudehen Islamic Azad University, Roudehen, Iran
| | - Parviz Shahabi
- Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
| | - Koorosh Shahpasand
- Department of Brain and Cognitive Sciences, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran.
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Gholami M, Saboory E, Ahmadi AA, Asouri M, Nasirikenari M, Rostamnezhad M. Long-time effects of prenatal morphine, tramadol, methadone, and buprenorphine exposure on seizure and anxiety in immature rats. Int J Neurosci 2019; 130:898-905. [PMID: 31877061 DOI: 10.1080/00207454.2019.1709841] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Purpose: This study aimed to investigate seizures and anxiety-like behaviors in immature rats prenatally exposed to opiate drugs.Materials and methods: Pregnant rats were randomly divided into five groups: saline, morphine, tramadol, methadone, and buprenorphine. Administrations were performed intraperitoneally once a day for the last seven days of pregnancy. Neonatal rats were subdivided into ten groups, split according to sex. Anxiety-like behavior was tested on postnatal day (PD) 19. On PD 20, seizure was induced by PTZ injection.Results: Morphine in male rats had an increased time to onset (p < 0.005), whereas there was a decreased number of tonic-clonic seizures in females (p < 0.05). Tramadol had an increased duration of tonic-clonic seizures compared to morphine and methadone in males (p < 0.005). Moreover, tramadol decreased open arm time and locomotor activity in males more than in females (p < 0.05). Methadone decreased open arm time in males (p < 0.05). Furthermore, buprenorphine and tramadol decreased open arm entrance in male rats (p < 0.05).Conclusions: It was demonstrated that prenatal tramadol significantly increases both the duration of seizures and anxiety-like behaviors in immature male rats, whereas morphine decreases both of them. The effects of tramadol on seizure and anxiety-like behavior may be due to the comorbid occurrence of the symptoms of these two disorders.
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Affiliation(s)
- Morteza Gholami
- North Research Center, Pasteur Institute of Iran, Amol, Iran.,Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran.,Obesity and Eating Habits Research Center, Endocrinology and Metabolism Molecular -Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Ehsan Saboory
- Zanjan Metabolic Diseases Research Center, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Ali Asghar Ahmadi
- North Research Center, Pasteur Institute of Iran, Amol, Iran.,Infertility and Reproductive Health Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
| | - Mohsen Asouri
- North Research Center, Pasteur Institute of Iran, Amol, Iran
| | | | - Mostafa Rostamnezhad
- Faculty of Pharmacy, Department of Pharmaceutics, Tehran University of Medical Sciences, Tehran, Iran
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4
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Azizi N, Roshan-Milani S, MahmoodKhani M, Saboory E, Gholinejad Z, Abdollahzadeh N, Sayyadi H, Chodari L. Parental pre-conception stress status and risk for anxiety in rat offspring: specific and sex-dependent maternal and paternal effects. Stress 2019; 22:619-631. [PMID: 31131701 DOI: 10.1080/10253890.2019.1619075] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Prenatal stressful events have long-lasting consequences on behavioral responses of offspring. While the effects of gestational and maternal stress have been extensively studied on psychological alterations in the progeny, little is known about effects of each parent's pre-conception life events on emotional responses in offspring. Here, the effect of maternal and/or paternal pre-conception stress was investigated on anxiogenic responses of offspring. Male and female adult rats were subjected to predatory stress (contactless exposure to a cat for 1 + 1 h per day) for 50 (male, n: 12) and 15 (female, n: 24) consecutive days; controls were not exposed. After the stress procedure, the control and stressed rats were mated to create four types of breeding pairs: control female/control male, stressed female/control male, control female/stressed male, and stressed female/stressed male. On postnatal days 30-31, the offspring were tested on the elevated plus maze and plasma corticosterone concentration was measured. Half of the pups were exposed to acute predatory stress before the elevated plus maze test. In most subgroups, corticosterone and anxiety-like behaviors in the offspring with both or only one parent exposed to pre-gestational stress increased compared to their control counterparts. However, under acute stress conditions, a different sex-dependent pattern of anxiety responses emerged. The combined effects of maternal and paternal stress were not additive. Hence, individual offspring behaviors can be influenced by the former life stress experiences of either parent. Incorporation of genetic and epigenetic aspects in development of neurobehavioral abnormalities and reprograming of the hypothalamic-pituitary-adrenal axis may contribute to this phenomenon. Lay summary Early life stress (including during pregnancy) is known to have long-lasting effects on offspring, including emotional behaviors. Whether individual anxiety behaviors can be influenced by stress experiences of each parent even before a pregnancy is less well-understood. Our findings from this study on rats exposed to predator stress before mating suggest that maternal or paternal adult life events prior to pregnancy can lead to maladaptive behavior in their offspring later in life.
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Affiliation(s)
- Negar Azizi
- a Department of Physiology, Faculty of Medicine, Urmia University of Medical Sciences , Urmia , Iran
- b Cellular and Molecular Research Center, Urmia University of Medical Sciences , Urmia , Iran
| | - Shiva Roshan-Milani
- a Department of Physiology, Faculty of Medicine, Urmia University of Medical Sciences , Urmia , Iran
- c Neurophysiology Research Center, Urmia University of Medical Sciences , Urmia , Iran
| | - Maryam MahmoodKhani
- b Cellular and Molecular Research Center, Urmia University of Medical Sciences , Urmia , Iran
- c Neurophysiology Research Center, Urmia University of Medical Sciences , Urmia , Iran
| | - Ehsan Saboory
- a Department of Physiology, Faculty of Medicine, Urmia University of Medical Sciences , Urmia , Iran
- c Neurophysiology Research Center, Urmia University of Medical Sciences , Urmia , Iran
| | - Zafar Gholinejad
- d Department of Clinical Biochemistry, Faculty of Medicine, Urmia University of Medical Sciences , Urmia , Iran
| | - Naseh Abdollahzadeh
- a Department of Physiology, Faculty of Medicine, Urmia University of Medical Sciences , Urmia , Iran
| | - Hojjat Sayyadi
- c Neurophysiology Research Center, Urmia University of Medical Sciences , Urmia , Iran
| | - Leila Chodari
- a Department of Physiology, Faculty of Medicine, Urmia University of Medical Sciences , Urmia , Iran
- c Neurophysiology Research Center, Urmia University of Medical Sciences , Urmia , Iran
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Bao W, Volgin AD, Alpyshov ET, Friend AJ, Strekalova TV, de Abreu MS, Collins C, Amstislavskaya TG, Demin KA, Kalueff AV. Opioid Neurobiology, Neurogenetics and Neuropharmacology in Zebrafish. Neuroscience 2019; 404:218-232. [PMID: 30710667 DOI: 10.1016/j.neuroscience.2019.01.045] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 01/22/2019] [Accepted: 01/23/2019] [Indexed: 01/28/2023]
Abstract
Despite the high prevalence of medicinal use and abuse of opioids, their neurobiology and mechanisms of action are not fully understood. Experimental (animal) models are critical for improving our understanding of opioid effects in vivo. As zebrafish (Danio rerio) are increasingly utilized as a powerful model organism in neuroscience research, mounting evidence suggests these fish as a useful tool to study opioid neurobiology. Here, we discuss the zebrafish opioid system with specific focus on opioid gene expression, existing genetic models, as well as its pharmacological and developmental regulation. As many human brain diseases involve pain and aberrant reward, we also summarize zebrafish models relevant to opioid regulation of pain and addiction, including evidence of functional interplay between the opioid system and central dopaminergic and other neurotransmitter mechanisms. Additionally, we critically evaluate the limitations of zebrafish models for translational opioid research and emphasize their developing utility for improving our understanding of evolutionarily conserved mechanisms of pain-related, addictive, affective and other behaviors, as well as for fostering opioid-related drug discovery.
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Affiliation(s)
- Wandong Bao
- School of Pharmacy and School of Life Sciences, Southwest University, Chongqing, China
| | - Andrey D Volgin
- Military Medical Academy, St. Petersburg, Russia; Institute of Experimental Medicine, Almazov National Medical Research Centre, Ministry of Healthcare of Russian Federation, St. Petersburg, Russia; Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia; Scientific Research Institute of Physiology and Basic Medicine, Novosibirsk, Russia
| | - Erik T Alpyshov
- School of Pharmacy and School of Life Sciences, Southwest University, Chongqing, China
| | - Ashton J Friend
- Tulane University School of Science and Engineering, New Orleans, LA, USA; The International Zebrafish Neuroscience Research Consortium, New Orleans, LA, USA
| | - Tatyana V Strekalova
- Sechenov First Moscow State Medical University, Institute of Molecular Medicine, Laboratory of Psychiatric Neurobiology and Department of Normal Physiology, Moscow, Russia; Department of Neuroscience, Maastricht University, Maastricht, Netherlands; Institute of General Pathology and Pathophysiology, Moscow, Russia
| | - Murilo S de Abreu
- The International Zebrafish Neuroscience Research Consortium, New Orleans, LA, USA; Bioscience Institute, University of Passo Fundo (UPF), Passo Fundo, RS, Brazil
| | - Christopher Collins
- ZENEREI Research Center, Slidell, LA, USA; The International Zebrafish Neuroscience Research Consortium, New Orleans, LA, USA
| | - Tamara G Amstislavskaya
- Scientific Research Institute of Physiology and Basic Medicine, Novosibirsk, Russia; The International Zebrafish Neuroscience Research Consortium, New Orleans, LA, USA
| | - Konstantin A Demin
- Institute of Experimental Medicine, Almazov National Medical Research Centre, Ministry of Healthcare of Russian Federation, St. Petersburg, Russia; Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia
| | - Allan V Kalueff
- School of Pharmacy and School of Life Sciences, Southwest University, Chongqing, China; Institute of Experimental Medicine, Almazov National Medical Research Centre, Ministry of Healthcare of Russian Federation, St. Petersburg, Russia; Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia; Ural Federal University, Ekaterinburg, Russia; Granov Russian Research Center of Radiology and Surgical Technologies, Ministry of Healthcare of Russian Federation, Pesochny, Russia; Scientific Research Institute of Physiology and Basic Medicine, Novosibirsk, Russia; ZENEREI Research Center, Slidell, LA, USA; The International Zebrafish Neuroscience Research Consortium, New Orleans, LA, USA.
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6
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Azmy SM, Abd El fattah MA, Abd El-Rahman SS, Nada SA, Abdel Salam OM, El-Yamany MF, Nassar NN. Does nicotine impact tramadol abuse? Insights from neurochemical and neurobehavioral changes in mice. Neurotoxicology 2018; 67:245-258. [DOI: 10.1016/j.neuro.2018.06.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 05/16/2018] [Accepted: 06/10/2018] [Indexed: 02/06/2023]
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7
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Nakhjiri E, Saboory E, Roshan-Milani S, Rasmi Y, Sayyadi H. Prenatal Stress+Morphine and Postnatal Re-exposure to Stress Alter Pentylenetetrazol-Induced Epileptic Manifestations in Rats. NEUROPHYSIOLOGY+ 2017. [DOI: 10.1007/s11062-017-9610-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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8
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Nakhjiri E, Saboory E, Roshan-Milani S, Rasmi Y, Khalafkhani D. Effect of prenatal restraint stress and morphine co-administration on plasma vasopressin concentration and anxiety behaviors in adult rat offspring. Stress 2017; 20:205-211. [PMID: 28287019 DOI: 10.1080/10253890.2017.1306053] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Stressful events and exposure to opiates during gestation have important effects on the later mental health of the offspring. Anxiety is among the most common mental disorders. The present study aimed to identify effects of prenatal restraint stress and morphine co-administration on plasma vasopressin concentration (PVC) and anxiety behaviors in rats. Pregnant rats were divided into four groups (n = 6, each): saline, morphine, stress + saline and stress + morphine treatment. The stress procedure consisted of restraint twice per day, two hours per session, for three consecutive days starting on day 15 of pregnancy. Rats in the saline and morphine groups received either 0.9% saline or morphine intraperitoneally on the same days. In the morphine/saline + stress groups, rats were exposed to restraint stress and received either morphine or saline intraperitoneally. All offspring were tested in an elevated plus maze (EPM) on postnatal day 90 (n = 6, each sex), and anxiety behaviors of each rat were recorded. Finally, blood samples were collected to determine PVC. Prenatal morphine exposure reduced anxiety-like behaviors. Co-administration of prenatal stress and morphine increased locomotor activity (LA) and PVC. PVC was significantly lower in female offspring of the morphine and morphine + stress groups compared with males in the same group, but the opposite was seen in the saline + stress group. These data emphasize the impact of prenatal stress and morphine on fetal neuroendocrine development, with long-term changes in anxiety-like behaviors and vasopressin secretion. These changes are sex specific, indicating differential impact of prenatal stress and morphine on fetal neuroendocrine system development. Lay Summary Pregnant women are sometimes exposed to stressful and painful conditions which may lead to poor outcomes for offspring. Opiates may provide pain and stress relief to these mothers. In this study, we used an experimental model of maternal exposure to stress and morphine in pregnant rats. The findings indicated that maternal stress increased anxiety in offspring while morphine decreased such effects, but had negative effects on the levels of a hormone controlling blood pressure, and activity of offspring. Hence morphine should not be used in pregnancy for pain and stress relief.
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Affiliation(s)
- Elnaz Nakhjiri
- a Studental Research Committee , Urmia University of Medical Sciences , Urmia , Iran
| | - Ehsan Saboory
- b Neurophysiology Research Center, Urmia University of Medical Sciences , Urmia , Iran
| | - Shiva Roshan-Milani
- c Department of Physiology, Faculty of Medicine , Urmia University of Medical Sciences , Urmia , Iran
| | - Yousef Rasmi
- d Cellular and Molecular Research Center, Urmia University of Medical Sciences , Urmia , Iran
| | - Davod Khalafkhani
- d Cellular and Molecular Research Center, Urmia University of Medical Sciences , Urmia , Iran
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Abstract
This paper is the thirty-eighth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2015 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, Flushing, NY 11367, United States.
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10
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Morphine exposure during early life alters thermal and mechanical thresholds in rats. Int J Dev Neurosci 2016; 60:78-85. [DOI: 10.1016/j.ijdevneu.2016.12.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 12/04/2016] [Accepted: 12/29/2016] [Indexed: 12/20/2022] Open
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Jiang H, Fang D, Kong LY, Jin ZR, Cai J, Kang XJ, Wan Y, Xing GG. Sensitization of neurons in the central nucleus of the amygdala via the decreased GABAergic inhibition contributes to the development of neuropathic pain-related anxiety-like behaviors in rats. Mol Brain 2014; 7:72. [PMID: 25277376 PMCID: PMC4201706 DOI: 10.1186/s13041-014-0072-z] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 09/18/2014] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Despite high prevalence of anxiety accompanying with chronic pain, the mechanisms underlying pain-related anxiety are largely unknown. With its well-documented role in pain and emotion processing, the amygdala may act as a key player in pathogenesis of neuropathic pain-related anxiety. Pain-related plasticity and sensitization of CeA (central nucleus of the amygdala) neurons have been shown in several models of chronic pain. In addition, firing pattern of neurons with spike output can powerfully affect functional output of the brain nucleus, and GABAergic neurons are crucial in the modulation of neuronal excitability. In this study, we first investigated whether pain-related plasticity (e.g. alteration of neuronal firing patterns) and sensitization of CeA neurons contribute to nerve injury-evoked anxiety in neuropathic rats. Furthermore, we explored whether GABAergic disinhibition is responsible for regulating firing patterns and intrinsic excitabilities of CeA neurons as well as for pain-related anxiety in neuropathic rats. RESULTS We discovered that spinal nerve ligation (SNL) produced neuropathic pain-related anxiety-like behaviors in rats, which could be specifically inhibited by intra-CeA administration of anti-anxiety drug diazepam. Moreover, we found potentiated plasticity and sensitization of CeA neurons in SNL-induced anxiety rats, of which including: 1) increased burst firing pattern and early-adapting firing pattern; 2) increased spike frequency and intrinsic excitability; 3) increased amplitude of both after-depolarized-potential (ADP) and sub-threshold membrane potential oscillation. In addition, we observed a remarkable reduction of GABAergic inhibition in CeA neurons in SNL-induced anxiety rats, which was proved to be important for altered firing patterns and hyperexcitability of CeA neurons, thereby greatly contributing to the development of neuropathic pain-related anxiety. Accordantly, activation of GABAergic inhibition by intra-CeA administration of muscimol, a selective GABAA receptors agonist, could inhibit SNL-induced anxiety-like behaviors in neuropathic rats. By contrast, suppression of GABAergic inhibition by intra-CeA administration of bicuculline, a selective GABAA receptors antagonist, produced anxiety-like behavior in normal rats. CONCLUSIONS This study suggests that reduction of GABAergic inhibition may be responsible for potentiated plasticity and sensitization of CeA neurons, which likely underlie the enhanced output of amygdala and neuropathic pain-related anxiety in SNL rats.
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Affiliation(s)
- Hong Jiang
- Neuroscience Research Institute, Peking University, 38 Xue-Yuan Road, Beijing, 100191, P.R. China.
| | - Dong Fang
- Neuroscience Research Institute, Peking University, 38 Xue-Yuan Road, Beijing, 100191, P.R. China.
| | - Ling-Yu Kong
- Neuroscience Research Institute, Peking University, 38 Xue-Yuan Road, Beijing, 100191, P.R. China.
| | - Zi-Run Jin
- Neuroscience Research Institute, Peking University, 38 Xue-Yuan Road, Beijing, 100191, P.R. China.
| | - Jie Cai
- Neuroscience Research Institute, Peking University, 38 Xue-Yuan Road, Beijing, 100191, P.R. China.
| | - Xue-Jing Kang
- Neuroscience Research Institute, Peking University, 38 Xue-Yuan Road, Beijing, 100191, P.R. China.
| | - You Wan
- Department of Neurobiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, P.R. China. .,Key Laboratory for Neuroscience, Ministry of Education and Ministry of Health, Beijing, 100191, P.R. China.
| | - Guo-Gang Xing
- Neuroscience Research Institute, Peking University, 38 Xue-Yuan Road, Beijing, 100191, P.R. China. .,Department of Neurobiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, P.R. China. .,Key Laboratory for Neuroscience, Ministry of Education and Ministry of Health, Beijing, 100191, P.R. China.
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