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Allen HN, Chaudhry S, Hong VM, Lewter LA, Sinha GP, Carrasquillo Y, Taylor BK, Kolber BJ. A Parabrachial-to-Amygdala Circuit That Determines Hemispheric Lateralization of Somatosensory Processing. Biol Psychiatry 2023; 93:370-381. [PMID: 36473754 PMCID: PMC9852076 DOI: 10.1016/j.biopsych.2022.09.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 09/07/2022] [Accepted: 09/10/2022] [Indexed: 02/04/2023]
Abstract
BACKGROUND The central amygdala (CeA) is a bilateral hub of pain and emotional processing with well-established functional lateralization. We reported that optogenetic manipulation of neural activity in the left and right CeA has opposing effects on bladder pain. METHODS To determine the influence of calcitonin gene-related peptide (CGRP) signaling from the parabrachial nucleus on this diametrically opposed lateralization, we administered CGRP and evaluated the activity of CeA neurons in acute brain slices as well as the behavioral signs of bladder pain in the mouse. RESULTS We found that CGRP increased firing in both the right and left CeA neurons. Furthermore, we found that CGRP administration in the right CeA increased behavioral signs of bladder pain and decreased bladder pain-like behavior when administered in the left CeA. CONCLUSIONS These studies reveal a parabrachial-to-amygdala circuit driven by opposing actions of CGRP that determines hemispheric lateralization of visceral pain.
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Affiliation(s)
- Heather N Allen
- Department of Biological Sciences, Duquesne University, Pittsburgh, Pennsylvania; Department of Neuroscience and Center for Advanced Pain Studies, The University of Texas at Dallas, Richardson, Texas; Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania; Department of Anesthesiology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Sarah Chaudhry
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, Maryland
| | - Veronica M Hong
- Department of Neuroscience and Center for Advanced Pain Studies, The University of Texas at Dallas, Richardson, Texas
| | - Lakeisha A Lewter
- Department of Neuroscience and Center for Advanced Pain Studies, The University of Texas at Dallas, Richardson, Texas
| | - Ghanshyam P Sinha
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Yarimar Carrasquillo
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, Maryland
| | - Bradley K Taylor
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania; Department of Anesthesiology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Benedict J Kolber
- Department of Neuroscience and Center for Advanced Pain Studies, The University of Texas at Dallas, Richardson, Texas.
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Smirnova MP, Medvedeva TM, Pavlova IV, Vinogradova LV. Region-Specific Vulnerability of the Amygdala to Injury-Induced Spreading Depolarization. Biomedicines 2022; 10:biomedicines10092183. [PMID: 36140284 PMCID: PMC9496012 DOI: 10.3390/biomedicines10092183] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 08/29/2022] [Accepted: 08/31/2022] [Indexed: 11/16/2022] Open
Abstract
Spreading depolarization (SD), a self-propagated wave of transient depolarization, regularly occurs in the cortex after acute brain insults and is now referred as an important diagnostic and therapeutic target in patients with acute brain injury. Here, we show that the amygdala, the limbic structure responsible for post-injury neuropsychological symptoms, exhibits strong regional heterogeneity in vulnerability to SD with high susceptibility of its basolateral (BLA) region and resilience of its centromedial (CMA) region to triggering SD by acute focal damage. The BLA micro-injury elicited SD twice as often compared with identical injury of the CMA region (71% vs. 33%). Spatiotemporal features of SDs triggered in the amygdala indicated diverse patterns of the SD propagation to the cortex. Our results suggest that even relatively small cerebral structures can exhibit regional gradients in their susceptibility to SD and the heterogeneity may contribute to the generation of complex SD patterns in the injured brain.
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Liu L, Dai L, Xu D, Wang Y, Bai L, Chen X, Li M, Yang S, Tang Y. Astrocyte secretes IL-6 to modulate PSD-95 palmitoylation in basolateral amygdala and depression-like behaviors induced by peripheral nerve injury. Brain Behav Immun 2022; 104:139-154. [PMID: 35636613 DOI: 10.1016/j.bbi.2022.05.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 04/26/2022] [Accepted: 05/25/2022] [Indexed: 02/05/2023] Open
Abstract
Dysfunction of glutamatergic synaptic plasticity in basolateral amygdala (BLA) constitutes a critical pathogenic mechanism underlying the depression-like behaviors induced by chronic pain. Astrocytes serve as an important supporting cell modulating glutamatergic synaptic transmission. Here, we found that peripheral spared nerve injury (SNI) induced astrocyte activation to release IL-6 in BLA. Inhibition of astrocyte activity attenuated SNI-induced IL-6 overexpression and depression-like behaviors. Moreover, SNI enhanced the abundance of DHHC2 in synaptosome and DHHC3 in Golgi apparatus, promoted PSD-95 palmitoylation, and increased the recruitment of GluR1 and NR2B at synapses. Suppression of IL-6 or PSD-95 palmitoylation attenuated the synaptic accumulation of GluR1 and NR2B in BLA and improved depression-like behaviors induced by SNI. Furthermore, IL-6 downstream PI3K increased the expression of DHHC3 in Golgi apparatus and facilitated the interaction of palmitoylated PSD-95 with GluR1 and NR2B at synapses. These findings collectively suggested that SNI activated astrocyte to release IL-6 in BLA, which promoted PSD-95 palmitoylation and enhanced the synaptic trafficking of GluR1 and NR2B, and subsequently mediated the depression-like behaviors induced by nerve injury.
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Affiliation(s)
- Lian Liu
- Department of Anesthesiology, West China Second University Hospital, Sichuan University, and Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu 610041, China; Division of Pulmonary Diseases, State Key Laboratory of Biotherapy, and Department of Respiratory Critical Care Medicine, West China Hospital, Sichuan University, Chengdu 610093, China
| | - Luqi Dai
- Division of Pulmonary Diseases, State Key Laboratory of Biotherapy, and Department of Respiratory Critical Care Medicine, West China Hospital, Sichuan University, Chengdu 610093, China
| | - Dan Xu
- Division of Pulmonary Diseases, State Key Laboratory of Biotherapy, and Department of Respiratory Critical Care Medicine, West China Hospital, Sichuan University, Chengdu 610093, China
| | - Yinchan Wang
- Core Facility of West China Hospital, Sichuan University, Chengdu 610093, China
| | - Lin Bai
- Core Facility of West China Hospital, Sichuan University, Chengdu 610093, China
| | - Xiaoting Chen
- Animal Experimental Center of West China Hospital, Sichuan University, Chengdu 610093, China
| | - Mengzhou Li
- Department of Anesthesiology, West China Second University Hospital, Sichuan University, and Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu 610041, China; West China School of Medicine, Sichuan University, Chengdu 610041, China
| | - Shuai Yang
- Department of Anesthesiology, West China Second University Hospital, Sichuan University, and Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu 610041, China; West China School of Medicine, Sichuan University, Chengdu 610041, China
| | - Yuying Tang
- Department of Anesthesiology, West China Second University Hospital, Sichuan University, and Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu 610041, China; Division of Pulmonary Diseases, State Key Laboratory of Biotherapy, and Department of Respiratory Critical Care Medicine, West China Hospital, Sichuan University, Chengdu 610093, China.
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Effects of Intra-BLA Administration of PPAR Antagonists on Formalin-Evoked Nociceptive Behaviour, Fear-Conditioned Analgesia, and Conditioned Fear in the Presence or Absence of Nociceptive Tone in Rats. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27062021. [PMID: 35335382 PMCID: PMC8949000 DOI: 10.3390/molecules27062021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/02/2022] [Accepted: 03/03/2022] [Indexed: 11/16/2022]
Abstract
There is evidence for the involvement of peroxisome proliferator-activated receptors (PPARs) in pain, cognition, and anxiety. However, their role in pain–fear interactions is unknown. The amygdala plays a key role in pain, conditioned fear, and fear-conditioned analgesia (FCA). We investigated the effects of intra-basolateral amygdala (BLA) administration of PPARα, PPARβ/δ, and PPARγ antagonists on nociceptive behaviour, FCA, and conditioned fear in the presence or absence of nociceptive tone. Male Sprague-Dawley (SD) rats received footshock (FC) or no footshock (NFC) in a conditioning arena. Twenty-three and a half hours later, rats received an intraplantar injection of formalin or saline and, 15 min later, intra-BLA microinjections of vehicle, PPARα (GW6471) PPARβ/δ (GSK0660), or PPARγ (GW9662) antagonists before arena re-exposure. Pain and fear-related behaviour were assessed, and neurotransmitters/endocannabinoids measured post-mortem. Intra-BLA administration of PPARα or PPARγ antagonists potentiated freezing in the presence of nociceptive tone. Blockade of all PPAR subtypes in the BLA increased freezing and BLA dopamine levels in NFC rats in the absence of nociceptive tone. Administration of intra-BLA PPARα and PPARγ antagonists increased levels of dopamine in the BLA compared with the vehicle-treated counterparts. In conclusion, PPARα and PPARγ in the BLA play a role in the expression or extinction of conditioned fear in the presence or absence of nociceptive tone.
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OUP accepted manuscript. Cereb Cortex 2022; 32:4619-4639. [DOI: 10.1093/cercor/bhab506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 12/07/2021] [Accepted: 12/08/2021] [Indexed: 11/13/2022] Open
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Liu J, Li D, Huang J, Cao J, Cai G, Guo Y, Wang G, Zhao S, Wang X, Wu S. Glutamatergic Neurons in the Amygdala Are Involved in Paclitaxel-Induced Pain and Anxiety. Front Psychiatry 2022; 13:869544. [PMID: 35492735 PMCID: PMC9049739 DOI: 10.3389/fpsyt.2022.869544] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 03/21/2022] [Indexed: 11/18/2022] Open
Abstract
Paclitaxel is widely used as a first-line chemotherapy agent to treat malignant tumors. However, paclitaxel causes peripheral nerve fiber damage and neuropathic pain in some patients. In addition, patients received paclitaxel chemotherapy are often accompanied by negative emotions such as anxiety. The amygdala is critically involved in regulating pain signals, as well as anxiety. The purpose of this study is to clarify the role of Ca2+/calmodulin-dependent protein kinase II (CaMKII)-positive glutamatergic neurons in the amygdala in paclitaxel-induced pain and negative affective symptoms. Intraperitoneal injection of paclitaxel into mice caused mechanical and thermal allodynia, as measured by Von Frey test and Hargreaves test, and anxiety, as measured by open field test and elevated plus maze test. Immunofluorescence staining revealed that c-fos-positive neurons were significantly more in the basolateral amygdala (BLA) and central amygdala (CeA) in paclitaxel-treated mice than untreated mice. Furthermore, part of c-fos-positive neurons in the BLA were immunoreactive of CaMKII. Engineered Designer receptors exclusively activated by designer drugs (DREADD) receptor hM4Di or hM3Dq was selectively expressed on CaMKII neurons by injection of adeno-associated virus (AAV) vectors containing CaMKII and hM4Di or hM3Dq. Administration of DREADD agonist CNO to selectively inhibit the CaMKII neurons in the BLA significantly increased the paw withdrawal thresholds and paw withdrawal latencies. In addition, selectively inhibition of CaMKII neurons in the BLA alleviated anxiety behavior without affecting the motor activity. In summary, our findings suggest that CaMKII neurons in the amygdala are critical for neuropathic pain and anxiety behaviors induced by paclitaxel chemotherapy.
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Affiliation(s)
- Jiaxin Liu
- Department of Anesthesiology, Third Affiliated Hospital of Hebei Medical University, Shijiazhuang, China
| | - Dangchao Li
- Department of Anesthesiology, Third Affiliated Hospital of Hebei Medical University, Shijiazhuang, China
| | - Jing Huang
- Department of Neurobiology, School of Basic Medicine, Fourth Military Medical University, Xi'an, China
| | - Jing Cao
- Department of Anesthesiology, Third Affiliated Hospital of Hebei Medical University, Shijiazhuang, China
| | - Guohong Cai
- Department of Neurobiology, School of Basic Medicine, Fourth Military Medical University, Xi'an, China
| | - Yuexian Guo
- Department of Surgery, Third Affiliated Hospital of Hebei Medical University, Shijiazhuang, China
| | - Guiying Wang
- Department of Surgery, Third Affiliated Hospital of Hebei Medical University, Shijiazhuang, China
| | - Shuang Zhao
- Department of Anesthesiology, Third Affiliated Hospital of Hebei Medical University, Shijiazhuang, China
| | - Xiuli Wang
- Department of Anesthesiology, Third Affiliated Hospital of Hebei Medical University, Shijiazhuang, China
| | - Shengxi Wu
- Department of Neurobiology, School of Basic Medicine, Fourth Military Medical University, Xi'an, China
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Presto P, Ji G, Junell R, Griffin Z, Neugebauer V. Fear Extinction-Based Inter-Individual and Sex Differences in Pain-Related Vocalizations and Anxiety-like Behaviors but Not Nocifensive Reflexes. Brain Sci 2021; 11:brainsci11101339. [PMID: 34679403 PMCID: PMC8533751 DOI: 10.3390/brainsci11101339] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/05/2021] [Accepted: 10/06/2021] [Indexed: 02/06/2023] Open
Abstract
Inter-individual and sex differences in pain responses are recognized but their mechanisms are not well understood. This study was intended to provide the behavioral framework for analyses of pain mechanisms using fear extinction learning as a predictor of phenotypic and sex differences in sensory (mechanical withdrawal thresholds) and emotional-affective aspects (open field tests for anxiety-like behaviors and audible and ultrasonic components of vocalizations) of acute and chronic pain. In acute arthritis and chronic neuropathic pain models, greater increases in vocalizations were found in females than males and in females with poor fear extinction abilities than females with strong fear extinction, particularly in the neuropathic pain model. Female rats showed higher anxiety-like behavior than males under baseline conditions but no inter-individual or sex differences were seen in the pain models. No inter-individual and sex differences in mechanosensitivity were observed. The data suggest that vocalizations are uniquely suited to detect inter-individual and sex differences in pain models, particularly in chronic neuropathic pain, whereas no such differences were found for mechanosensitivity, and baseline differences in anxiety-like behaviors disappeared in the pain models.
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Affiliation(s)
- Peyton Presto
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, 3601 4th St, Lubbock, TX 79430-6592, USA; (P.P.); (G.J.); (R.J.); (Z.G.)
| | - Guangchen Ji
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, 3601 4th St, Lubbock, TX 79430-6592, USA; (P.P.); (G.J.); (R.J.); (Z.G.)
- Center of Excellence for Translational Neuroscience and Therapeutics, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6592, USA
| | - Riley Junell
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, 3601 4th St, Lubbock, TX 79430-6592, USA; (P.P.); (G.J.); (R.J.); (Z.G.)
| | - Zach Griffin
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, 3601 4th St, Lubbock, TX 79430-6592, USA; (P.P.); (G.J.); (R.J.); (Z.G.)
| | - Volker Neugebauer
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, 3601 4th St, Lubbock, TX 79430-6592, USA; (P.P.); (G.J.); (R.J.); (Z.G.)
- Center of Excellence for Translational Neuroscience and Therapeutics, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6592, USA
- Garrison Institute on Aging, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6592, USA
- Correspondence: ; Tel.: +1-806-743-3880; Fax: +1-806-732-2744
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8
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Silva-Cardoso GK, Lazarini-Lopes W, Hallak JE, Crippa JA, Zuardi AW, Garcia-Cairasco N, Leite-Panissi CRA. Cannabidiol effectively reverses mechanical and thermal allodynia, hyperalgesia, and anxious behaviors in a neuropathic pain model: Possible role of CB1 and TRPV1 receptors. Neuropharmacology 2021; 197:108712. [PMID: 34274349 DOI: 10.1016/j.neuropharm.2021.108712] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 07/05/2021] [Accepted: 07/09/2021] [Indexed: 01/03/2023]
Abstract
The incidence of chronic pain is high in the general population and it is closely related to anxiety disorders, which promote negative effects on the quality of life. The cannabinoid system has essential participation in the pain sensitivity circuit. In this perspective, cannabidiol (CBD) is considered a promising strategy for treating neuropathic pain. Our study aimed to evaluate the effects of sub-chronic systemic treatment with CBD (0.3, 3, 10, or 30 mg/kg, i.p.) in male in rats submitted to chronic constriction injury of the sciatic nerve (CCI) or not (SHAM) and assessed in nociceptive tests (von Frey, acetone, and hot plate, three days CBD's treatment) and in the open field test (OFT, two days CBD's treatment). We performed a screening immunoreactivity of CB1 and TRPV1 receptors in cortical and limbic regions tissues, which were collected after 1.5 h of behavioral tests on the 24th experimental day. This study presents a dose-response curve to understand better the effects of low doses (3 mg/kg) on CBD's antiallodynic and anxiolytic effects. Also, low doses of CBD were able to (1) reverse mechanical and thermal allodynia (cold) and hyperalgesia, (2) reverse anxious behaviors (reduction of the % of grooming and freezing time, and increase of the % of center time in the OFT) induced by chronic pain. The peripheral neuropathy promoted the increase in the expression of CB1 and TRPV1 receptors in the anterior cingulate cortex (ACC), anterior insular cortex (AIC), basolateral amygdala (BLA), dorsal hippocampus (DH), and ventral hippocampus (VH). CBD potentiated this effect in the ACC, AIC, BLA, DH, and VH regions. These results provide substantial evidence of the role of the ACC-AIC-BLA corticolimbic circuit, and BLA-VH for pain regulation. These results can be clinically relevant since they contribute to the evidence of CBD's beneficial effects on treating chronic pain and associated comorbidities such as anxiety.
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Affiliation(s)
- Gleice K Silva-Cardoso
- Department of Psychology, Faculty of Philosophy, Science and Letters of Ribeirão Preto, University of São Paulo, Brazil; National Institute for Translational Medicine (INCT-TM; CNPq), São Paulo, Brazil
| | - Willian Lazarini-Lopes
- Department of Neuroscience and Behavioral Sciences, Ribeirão Preto School of Medicine, University of São Paulo, Brazil; National Institute for Translational Medicine (INCT-TM; CNPq), São Paulo, Brazil
| | - Jaime E Hallak
- Department of Neuroscience and Behavioral Sciences, Ribeirão Preto School of Medicine, University of São Paulo, Brazil; National Institute for Translational Medicine (INCT-TM; CNPq), São Paulo, Brazil
| | - José A Crippa
- Department of Neuroscience and Behavioral Sciences, Ribeirão Preto School of Medicine, University of São Paulo, Brazil; National Institute for Translational Medicine (INCT-TM; CNPq), São Paulo, Brazil
| | - Antonio W Zuardi
- Department of Neuroscience and Behavioral Sciences, Ribeirão Preto School of Medicine, University of São Paulo, Brazil; National Institute for Translational Medicine (INCT-TM; CNPq), São Paulo, Brazil
| | - Norberto Garcia-Cairasco
- Department of Neuroscience and Behavioral Sciences, Ribeirão Preto School of Medicine, University of São Paulo, Brazil; Department of Physiology, Ribeirão Preto School of Medicine, University of São Paulo, Brazil
| | - Christie R A Leite-Panissi
- Department of Psychology, Faculty of Philosophy, Science and Letters of Ribeirão Preto, University of São Paulo, Brazil; National Institute for Translational Medicine (INCT-TM; CNPq), São Paulo, Brazil.
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Yamaguchi T, Minami S, Ueda S. Effects of methylazoxymethanol-induced micrencephaly on parvalbumin-positive GABAergic interneurons in the rat rostral basolateral amygdala. Brain Res 2021; 1762:147425. [PMID: 33737065 DOI: 10.1016/j.brainres.2021.147425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 03/04/2021] [Accepted: 03/07/2021] [Indexed: 11/25/2022]
Abstract
The amygdala plays a crucial role in anxiety-related behavior and various neuropsychiatric disorders. The offspring of dams, administered methylazoxymethanol acetate (MAM) intraperitoneally at gestational day 15, exhibit micrencephaly and anxiety-related behavior, such as hyperactivity in rearing and crossing behavior, alongside a distinct Fos expression profile in the basolateral (BLA) and central amygdala. However, the histochemical underpinnings of these changes remain to be elucidated. To determine the histochemical alterations in MAM-induced model rats, we performed Nissl staining, immunohistochemistry for parvalbumin (PV) or calbindin (Calb), and immunohistochemistry for PV in conjunction with in situ hybridization for glutamate decarboxylase (GAD). We compared immunoreactivity in the BLA between normal and MAM-induced model rats and observed a significant decrease in the number of PV-positive neurons in MAM-induced model rats; however, no significant differences in the number of Nissl- and Calb-positive neurons were observed. We did not detect any significant between-group differences with regards to the effects of environmental enrichment on the number of PV-positive neurons in the BLA. Double-labeling for GAD and PV revealed that many PV-positive neurons colocalized with digoxigenin-GAD65/67 signals. In addition, GAD/PV double-positive neurons and the total number of GAD-positive neurons in the BLA were lower in the MAM-induced model rats. These results indicate that histochemical alterations observed in the BLA of the MAM-induced model rats may attribute to an aberrant GABAergic inhibitory system.
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Affiliation(s)
- Tsuyoshi Yamaguchi
- Department of Histology and Neurobiology, Dokkyo Medical University, School of Medicine, 880 Kitakobayashi, Mibu-machi, Shimotsuga-gun, Tochigi 321-0293, Japan.
| | - Shukuko Minami
- Department of Histology and Neurobiology, Dokkyo Medical University, School of Medicine, 880 Kitakobayashi, Mibu-machi, Shimotsuga-gun, Tochigi 321-0293, Japan
| | - Shuichi Ueda
- Department of Histology and Neurobiology, Dokkyo Medical University, School of Medicine, 880 Kitakobayashi, Mibu-machi, Shimotsuga-gun, Tochigi 321-0293, Japan
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Selective modulation of tonic aversive qualities of neuropathic pain by morphine in the central nucleus of the amygdala requires endogenous opioid signaling in the anterior cingulate cortex. Pain 2021; 161:609-618. [PMID: 31725062 DOI: 10.1097/j.pain.0000000000001748] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The amygdala is a key subcortical region believed to contribute to emotional components of pain. As opioid receptors are found in both the central (CeA) and basolateral (BLA) nuclei of the amygdala, we investigated the effects of morphine microinjection on evoked pain responses, pain-motivated behaviors, dopamine release in the nucleus accumbens (NAc), and descending modulation in rats with left-side spinal nerve ligation (SNL). Morphine administered into the right or left CeA had no effect on nerve injury-induced tactile allodynia or mechanical hyperalgesia. Right, but not left, CeA morphine produced conditioned place preference (CPP) and increased extracellular dopamine in the NAc selectively in SNL rats, suggesting relief of aversive qualities of ongoing pain. In SNL rats, CPP and NAc dopamine release following right CeA morphine was abolished by blocking mu opioid receptor signaling in the rostral anterior cingulate cortex (rACC). Right CeA morphine also significantly restored SNL-induced loss of the diffuse noxious inhibitory controls, a spino-bulbo-spinal pain modulatory mechanism, termed conditioned pain modulation in humans. Microinjection of morphine into the BLA had no effects on evoked behaviors and did not produce CPP in nerve-injured rats. These findings demonstrate that the amygdalar action of morphine is specific to the right CeA contralateral to the side of injury and results in enhancement of net descending inhibition. In addition, engagement of mu opioid receptors in the right CeA modulates affective qualities of ongoing pain through endogenous opioid neurotransmission within the rACC, revealing opioid-dependent functional connections from the CeA to the rACC.
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11
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Ji G, Neugebauer V. Kappa opioid receptors in the central amygdala modulate spinal nociceptive processing through an action on amygdala CRF neurons. Mol Brain 2020; 13:128. [PMID: 32948219 PMCID: PMC7501648 DOI: 10.1186/s13041-020-00669-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 09/09/2020] [Indexed: 12/11/2022] Open
Abstract
The amygdala plays an important role in the emotional-affective aspects of behaviors and pain, but can also modulate sensory aspect of pain ("nociception"), likely through coupling to descending modulatory systems. Here we explored the functional coupling of the amygdala to spinal nociception. We found that pharmacological activation of neurons in the central nucleus of the amygdala (CeA) increased the activity of spinal dorsal horn neurons; and this effect was blocked by optogenetic silencing of corticotropin releasing factor (CRF) positive CeA neurons. A kappa opioid receptor (KOR) agonist (U-69,593) was administered into the CeA by microdialysis. KOR was targeted because of their role in averse-affective behaviors through actions in limbic brain regions. Extracellular single-unit recordings were made of CeA neurons or spinal dorsal horn neurons in anesthetized transgenic Crh-Cre rats. Neurons responded more strongly to noxious than innocuous stimuli. U-69,593 increased the responses of CeA and spinal neurons to innocuous and noxious mechanical stimulation of peripheral tissues. The facilitatory effect of the agonist was blocked by optical silencing of CRF-CeA neurons though light activation of halorhodopsin expressed in these neurons by viral-vector. The CRF system in the amygdala has been implicated in aversiveness and pain modulation. The results suggest that the amygdala can modulate spinal nociceptive processing in a positive direction through CRF-CeA neurons and that KOR activation in the amygdala (CeA) has pro-nociceptive effects.
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Affiliation(s)
- Guangchen Ji
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, School of Medicine, 3601 4th St, Lubbock, TX, 79430-6592, USA
- Center of Excellence for Translational Neuroscience and Therapeutics, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Volker Neugebauer
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, School of Medicine, 3601 4th St, Lubbock, TX, 79430-6592, USA.
- Center of Excellence for Translational Neuroscience and Therapeutics, Texas Tech University Health Sciences Center, Lubbock, TX, USA.
- Garrison Institute on Aging, Texas Tech University Health Sciences Center, Lubbock, TX, USA.
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Nascimento GC, de Paula BB, Lowry CA, Leite-Panissi CRA. Temporomandibular inflammation mobilizes parvalbumin and FosB/deltaFosB neurons of amygdala and dorsal raphe. ACTA ACUST UNITED AC 2020; 53:e9950. [PMID: 32578721 PMCID: PMC7307894 DOI: 10.1590/1414-431x20209950] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 05/04/2020] [Indexed: 11/21/2022]
Abstract
Pathophysiological mechanisms involved in orofacial pain and their relationship with emotional disorders have emerged as an important research area for multidisciplinary studies. In particular, temporomandibular disorders (TMD) have been evaluated clinically from both physiological and psychological perspectives. We hypothesized that an altered neuronal activity occurs in the amygdala and the dorsal raphe nucleus (DR), encephalic regions involved in the modulation of painful and emotional information. Adult male Wistar rats were used in an experimental complete Freund's adjuvant (CFA)-induced temporomandibular joint (TMJ) inflammation model. CFA was applied for 1 or 10 days, and the animals were euthanized for brain samples dissection for FosB/ΔFosB and parvalbumin (PV) immunostaining. Our results were consistent in showing that the amygdala and DR were activated in the persistent inflammatory phase (10 days) and that the expression of PV+ interneurons in the amygdala was decreased. In contrast, in the DR, the expression of PV+ interneurons was increased in persistent states of CFA-induced TMJ inflammation. Moreover, at 10 days of inflammation, there was an increased co-localization of PV+ and FosB/ΔFosB+ neurons in the basolateral and central nucleus of the amygdala. Different nuclei of the amygdala, as well as portions of the DR, were activated in the persistent phase (10 days) of TMJ inflammation. In conclusion, altered activity of the amygdala and DR was detected during persistent inflammatory nociception in the temporomandibular joint. These regions may be essential for both sensory and affective dimensions of orofacial pain.
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Affiliation(s)
- G C Nascimento
- Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
| | - B B de Paula
- Departamento de Psicologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
| | - C A Lowry
- Department of Integrative Physiology and Center for Neuroscience, University of Colorado Boulder, Boulder, CO, USA
| | - C R A Leite-Panissi
- Departamento de Psicologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
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Xu L, Jiang H, Feng Y, Cao P, Ke J, Long X. Peripheral and central substance P expression in rat CFA-induced TMJ synovitis pain. Mol Pain 2020; 15:1744806919866340. [PMID: 31322474 PMCID: PMC6685108 DOI: 10.1177/1744806919866340] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Synovitis contributes to temporomandibular joint (TMJ) pain, nevertheless, the detailed nociceptive mechanism remains unclear. In this study, a rat model of TMJ synovitis was induced by intra-articular injection with complete Freund’s adjuvant (CFA). After CFA-induced synovitis, pain behaviors were observed. Then, TMJ, trigeminal ganglion, and trigeminal nucleus caudalis (TNC) tissues were collected, and immunohistochemistry was used to detect the expression of substance P (SP) and protein gene product 9.5 (PGP9.5) in the synovium tissue. Furthermore, the gene expression level of SP and PGP9.5 in synovium was detected by reverse transcription-polymerase chain reaction (RT-PCR). Afterwards, the expression of SP in the trigeminal ganglion and TNC and c-fos in the TNC was detected by immunohistochemistry. Compared with the control group, the expression of SP and PGP9.5 nerve fibers density and gene levels of them in the synovium tissue were significantly increased in CFA-induced TMJ synovitis rats. Similarly, SP expression in the trigeminal ganglion and TNC, and c-fos expression in the TNC were also obviously increased in CFA-induced TMJ synovitis rats. Collectively, CFA-induced rat TMJ synovitis resulted in obvious pain. This nociceptive reaction could be attributed to the augmented quantity of SP and PGP9.5 positive-stained nerve fibers distributed in the inflammatory synovium as well as enhanced SP expression in the trigeminal ganglion and TNC tissue. c-fos expression in the rat TNC illustrates CFA-induced TMJ synovitis can evoke the acute pain.
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Affiliation(s)
- Liqin Xu
- 1 State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Henghua Jiang
- 1 State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Yaping Feng
- 1 State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Pinyin Cao
- 1 State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Jin Ke
- 1 State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Xing Long
- 2 Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Wuhan University, Wuhan, China
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Electroacupuncture Alleviates Pain-Related Emotion by Upregulating the Expression of NPS and Its Receptor NPSR in the Anterior Cingulate Cortex and Hypothalamus. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2020; 2020:8630368. [PMID: 32104195 PMCID: PMC7035524 DOI: 10.1155/2020/8630368] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 01/07/2020] [Accepted: 01/16/2020] [Indexed: 12/14/2022]
Abstract
Objective Electroacupuncture (EA) is reported effective in alleviating pain-related emotion; however, the underlying mechanism of its effects still needs to be elucidated. The NPS-NPSR system has been validated for the involvement in the modulation of analgesia and emotional behavior. Here, we aimed to investigate the role of the NPS-NPSR system in the anterior cingulate cortex (ACC), hypothalamus, and central amygdala (CeA) in the use of EA to relieve affective pain modeled by complete Freund's adjuvant- (CFA-) evoked conditioned place aversion (C-CPA). Materials and Methods. CFA injection combined with a CPA paradigm was introduced to establish the C-CPA model, and the elevated O-maze (EOM) was used to test the behavioral changes after model establishment. We further explored the expression of NPS and NPSR at the protein and gene levels in the brain regions of interest by immunofluorescence staining and quantitative real-time PCR. Results We observed that EA stimulation delivered to the bilateral Zusanli (ST36) and Kunlun (BL60) acupoints remarkably inhibited sensory pain, pain-evoked place aversion, and anxiety-like behavior. The current study showed that EA significantly enhanced the protein expression of this peptide system in the ACC and hypothalamus, while the elevated expression of NPSR protein alone was just confined to the affected side in the CeA. Moreover, EA remarkably upregulated the mRNA expression of NPS in CeA, ACC, and hypothalamus and NPSR mRNA in the hypothalamus and CeA. Conclusions These data suggest the effectiveness of EA in alleviating affective pain, and these benefits may at least partially be attributable to the upregulation of the NPS-NPSR system in the ACC and hypothalamus.
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Abstract
This paper is the fortieth consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2017 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, CUNY, 65-30 Kissena Blvd., Flushing, NY, 11367, United States.
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Udobi KC, Delcimmuto N, Kokenge AN, Abdulla ZI, Perna MK, Skelton MR. Deletion of the creatine transporter gene in neonatal, but not adult, mice leads to cognitive deficits. J Inherit Metab Dis 2019; 42:966-974. [PMID: 31209903 PMCID: PMC6739135 DOI: 10.1002/jimd.12137] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 05/15/2019] [Accepted: 06/13/2019] [Indexed: 12/20/2022]
Abstract
Creatine (Cr) is a guanidino compound that provides readily available phosphate pools for the regeneration of spent adenosine triphosphate (ATP). The lack of brain Cr causes moderate to severe intellectual disability, language impairment, and epilepsy. The most prevalent cause of Cr deficiency are mutations in the X-linked SLC6A8 (Creatine transporter; CrT) gene, known as CrT deficiency (CTD). One of the most critical areas that need to be addressed is whether Cr is necessary for brain development. To address this concern, the Slc6a8 gene was knocked out in either neonatal (postnatal day (P)5) or adult (P60) mice using a tamoxifen-inducible Cre recombinase driven by the human ubiquitin C (UBC) promoter. Mice were tested in the Morris water maze, novel, object recognition, and conditioned fear 60 days after Slc6a8 deletion. In addition, overnight locomotor activity was analyzed. Mice that had the gene deleted on P5 showed deficits in the Morris water maze and novel object recognition, while there were no deficits in P60 knockout mice. Interestingly, the P5 knockout mice showed hyperactivity during the dark phase; however, when examining control mice, the effect was due to the administration of tamoxifen from P5 to 10. Taken together, the results of this study show that Cr is necessary during periods of brain development involved in spatial and object learning. This study also highlights the continued importance of using proper control groups for behavioral testing.
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Segklia K, Stamatakis A, Stylianopoulou F, Lavdas AA, Matsas R. Increased Anxiety-Related Behavior, Impaired Cognitive Function and Cellular Alterations in the Brain of Cend1-deficient Mice. Front Cell Neurosci 2019; 12:497. [PMID: 30760981 PMCID: PMC6361865 DOI: 10.3389/fncel.2018.00497] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 12/03/2018] [Indexed: 01/09/2023] Open
Abstract
Cend1 is a neuronal-lineage specific modulator involved in coordination of cell cycle exit and differentiation of neuronal precursors. We have previously shown that Cend1-/- mice show altered cerebellar layering caused by increased proliferation of granule cell precursors, delayed radial granule cell migration and compromised Purkinje cell differentiation, leading to ataxic gait and deficits in motor coordination. To further characterize the effects of Cend1 genetic ablation we determined herein a range of behaviors, including anxiety and exploratory behavior in the elevated plus maze (EPM), associative learning in fear conditioning, and spatial learning and memory in the Morris water maze (MWM). We observed significant deficits in all tests, suggesting structural and/or functional alterations in brain regions such as the cortex, amygdala and the hippocampus. In agreement with these findings, immunohistochemistry revealed reduced numbers of γ amino butyric acid (GABA) GABAergic interneurons, but not of glutamatergic projection neurons, in the adult cerebral cortex. Reduced GABAergic interneurons were also observed in the amygdala, most notably in the basolateral nucleus. The paucity in GABAergic interneurons in adult Cend1-/- mice correlated with increased proliferation and apoptosis as well as reduced migration of neuronal progenitors from the embryonic medial ganglionic eminence (MGE), the origin of these cells. Further we noted reduced GABAergic neurons and aberrant neurogenesis in the adult dentate gyrus (DG) of the hippocampus, which has been previously shown to confer spatial learning and memory deficits. Our data highlight the necessity of Cend1 expression in the formation of a structurally and functionally normal brain phenotype.
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Affiliation(s)
- Katerina Segklia
- Laboratory of Cellular and Molecular Neurobiology-Stem Cells, Department of Neurobiology, Hellenic Pasteur Institute, Athens, Greece
| | - Antonios Stamatakis
- Biology-Biochemistry Lab, Faculty of Nursing, School of Health Sciences, National and Kapodistrian University of Athens, Athens, Greece
| | - Fotini Stylianopoulou
- Biology-Biochemistry Lab, Faculty of Nursing, School of Health Sciences, National and Kapodistrian University of Athens, Athens, Greece
| | - Alexandros A Lavdas
- Laboratory of Cellular and Molecular Neurobiology-Stem Cells, Department of Neurobiology, Hellenic Pasteur Institute, Athens, Greece
| | - Rebecca Matsas
- Laboratory of Cellular and Molecular Neurobiology-Stem Cells, Department of Neurobiology, Hellenic Pasteur Institute, Athens, Greece
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Li JN, Sheets PL. The central amygdala to periaqueductal gray pathway comprises intrinsically distinct neurons differentially affected in a model of inflammatory pain. J Physiol 2018; 596:6289-6305. [PMID: 30281797 DOI: 10.1113/jp276935] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 09/19/2018] [Indexed: 01/15/2023] Open
Abstract
KEY POINTS The central nucleus of the amygdala (CeA) encompasses the main output pathways of the amygdala, a temporal lobe structure essential in affective and cognitive dimensions of pain. A major population of neurons in the CeA send projections to the periaqueductal gray (PAG), a key midbrain structure that mediates coping strategies in response to threat or stress. CeA-PAG neurons are topographically organized based on their targeted subregion within the PAG. PAG-projecting neurons in the central medial (CeM) and central lateral (CeL) regions of CeA are intrinsically distinct. CeL-PAG neurons are a homogeneous population of intrinsically distinct neurons while CeM-PAG neurons are intrinsically heterogeneous. Membrane properties of distinct CeM-PAG subtypes are altered in the complete Freund's adjuvant model of inflammatory pain. ABSTRACT A major population of neurons in the central nucleus of amygdala (CeA) send projections to the periaqueductal gray (PAG), a key midbrain structure that mediates coping strategies in response to threat or stress. While the CeA-PAG pathway has proved to be a component of descending anti-nociceptive circuitry, the functional organization of CeA-PAG neurons remains unclear. We identified CeA-PAG neurons in C57BL/6 mice of both sexes using intracranial injection of a fluorescent retrograde tracer into the PAG. In acute brain slices, we investigated the topographical and intrinsic characteristics of retrogradely labelled CeA-PAG neurons using epifluorescence and whole-cell electrophysiology. We also measured changes to CeA-PAG neurons in the complete Freund's adjuvant (CFA) model of inflammatory pain. Neurons in the central lateral (CeL) and central medial (CeM) amygdala project primarily to different regions of the PAG. CeL-PAG neurons consist of a relatively homogeneous population of intrinsically distinct neurons while CeM-PAG neurons are intrinsically heterogeneous. Membrane properties of distinct CeM-PAG subtypes are altered 1 day after induction of the CFA inflammatory pain model. Collectively, our results provide insight into pain-induced changes to a specific population of CeA neurons that probably play a key role in the integration of noxious input with endogenous analgesia and behavioural coping response.
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Affiliation(s)
- Jun-Nan Li
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA.,Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Patrick L Sheets
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA.,Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
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Issa HA, Staes N, Diggs-Galligan S, Stimpson CD, Gendron-Fitzpatrick A, Taglialatela JP, Hof PR, Hopkins WD, Sherwood CC. Comparison of bonobo and chimpanzee brain microstructure reveals differences in socio-emotional circuits. Brain Struct Funct 2018; 224:239-251. [DOI: 10.1007/s00429-018-1751-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 09/09/2018] [Indexed: 12/24/2022]
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Ji G, Yakhnitsa V, Kiritoshi T, Presto P, Neugebauer V. Fear extinction learning ability predicts neuropathic pain behaviors and amygdala activity in male rats. Mol Pain 2018; 14:1744806918804441. [PMID: 30209982 PMCID: PMC6172937 DOI: 10.1177/1744806918804441] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 08/15/2018] [Accepted: 09/02/2018] [Indexed: 12/14/2022] Open
Abstract
Background The amygdala plays a key role in fear learning and extinction and has emerged as an important node of emotional-affective aspects of pain and pain modulation. Impaired fear extinction learning, which involves prefrontal cortical control of amygdala processing, has been linked to neuropsychiatric disorders. Here, we tested the hypothesis that fear extinction learning ability can predict the magnitude of neuropathic pain. Results We correlated fear extinction learning in naive adult male rats with sensory and affective behavioral outcome measures (mechanical thresholds, vocalizations, and anxiety- and depression-like behaviors) before and after the induction of the spinal nerve ligation model of neuropathic pain compared to sham controls. Auditory fear conditioning, extinction learning, and extinction retention tests were conducted after baseline testing. All rats showed increased freezing responses after fear conditioning. During extinction training, the majority (75%) of rats showed a decline in freezing level to 50% in 5 min (fear extinction+), whereas 25% of the rats maintained a high freezing level (>50%, fear extinction-). Fear extinction- rats showed decreased open-arm preference in the elevated plus maze, reflecting anxiety-like behavior, but there were no significant differences in sensory thresholds, vocalizations, or depression-like behavior (forced swim test) between fear extinction+ and fear extinction- types. In the neuropathic pain model (four weeks after spinal nerve ligation), fear extinction- rats showed a greater increase in vocalizations and anxiety-like behavior than fear extinction+ rats. Fear extinction- rats, but not fear extinction+ rats, also developed depression-like behavior. Extracellular single unit recordings of amygdala (central nucleus) neurons in behaviorally tested rats (anesthetized with isoflurane) found greater increases in background activity, bursting, and evoked activity in fear extinction- rats than fear extinction+ rats in the spinal nerve ligation model compared to sham controls. Conclusion The data may suggest that fear extinction learning ability predicts the magnitude of neuropathic pain-related affective rather than sensory behaviors, which correlates with differences in amygdala activity changes.
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Affiliation(s)
- Guangchen Ji
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, School of Medicine, Lubbock, TX, USA
- Center of Excellence for Translational Neuroscience and Therapeutics, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Vadim Yakhnitsa
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, School of Medicine, Lubbock, TX, USA
| | - Takaki Kiritoshi
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, School of Medicine, Lubbock, TX, USA
| | - Peyton Presto
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, School of Medicine, Lubbock, TX, USA
| | - Volker Neugebauer
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, School of Medicine, Lubbock, TX, USA
- Center of Excellence for Translational Neuroscience and Therapeutics, Texas Tech University Health Sciences Center, Lubbock, TX, USA
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