1
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Huerta MÁ, Cisneros E, Alique M, Roza C. Strategies for Measuring Non-Evoked Pain in Preclinical Models of Neuropathic Pain: Systematic Review. Neurosci Biobehav Rev 2024; 163:105761. [PMID: 38852847 DOI: 10.1016/j.neubiorev.2024.105761] [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: 05/06/2024] [Revised: 05/28/2024] [Accepted: 06/04/2024] [Indexed: 06/11/2024]
Abstract
The development of new analgesics for neuropathic pain treatment is crucial. The failure of promising drugs in clinical trials may be related to the over-reliance on reflex-based responses (evoked pain) in preclinical drug testing, which may not fully represent clinical neuropathic pain, characterized by spontaneous non-evoked pain (NEP). Hence, strategies for assessing NEP in preclinical studies emerged. This systematic review identified 443 articles evaluating NEP in neuropathic pain models (mainly traumatic nerve injuries in male rodents). An exponential growth in NEP evaluation was observed, which was assessed using 48 different tests classified in 12 NEP-related outcomes: anxiety, exploration/locomotion, paw lifting, depression, conditioned place preference, gait, autotomy, wellbeing, facial grooming, cognitive impairment, facial pain expressions and vocalizations. Although most of these outcomes showed clear limitations, our analysis suggests that conditioning-associated outcomes, pain-related comorbidities, and gait evaluation may be the most effective strategies. Moreover, a minimal part of the studies evaluated standard analgesics. The greater emphasis on evaluating NEP aligning with clinical pain symptoms may enhance analgesic drug development, improving clinical translation.
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Affiliation(s)
- Miguel Á Huerta
- Department of Pharmacology, Faculty of Medicine, University of Granada, 18016 Granada, Spain; Institute of Neuroscience, Biomedical Research Center, University of Granada, 18100 Armilla, Granada, Spain; Biosanitary Research Institute ibs.GRANADA, 18012 Granada, Spain
| | - Elsa Cisneros
- Health Sciences School, Centro Universitario Internacional de Madrid (CUNIMAD), Madrid, Spain; Health Sciences School, Universidad Internacional de La Rioja (UNIR), Logroño, Spain
| | - Matilde Alique
- Department of System's Biology, Medical School, University of Alcala de Henares, Alcalá de Henares, Spain; Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
| | - Carolina Roza
- Department of System's Biology, Medical School, University of Alcala de Henares, Alcalá de Henares, Spain.
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2
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Zhang Y, Yao A, Wu J, Li S, Wang M, Peng Z, Sung HW, Jiang B, Li RK. Conductive Hydrogel Restores Electrical Conduction to Promote Neurological Recovery in a Rat Model. Tissue Eng Part A 2024. [PMID: 38661545 DOI: 10.1089/ten.tea.2023.0372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024] Open
Abstract
Spinal cord injury (SCI), caused by significant physical trauma, as well as other pathological conditions, results in electrical signaling disruption and loss of bodily functional control below the injury site. Conductive biomaterials have been considered a promising approach for treating SCI, owing to their ability to restore electrical connections between intact spinal cord portions across the injury site. In this study, we evaluated the ability of a conductive hydrogel, poly-3-amino-4-methoxybenzoic acid-gelatin (PAMB-G), to restore electrical signaling and improve neuronal regeneration in a rat SCI model generated using the compression clip method. Gelatin or PAMB-G was injected at the SCI site, yielding three groups: Control (saline), Gelatin, and PAMB-G. During the 8-week study, PAMB-G, compared to Control, had significantly lower proinflammatory factor expression, such as for tumor necrosis factor -α (0.388 ± 0.276 for PAMB-G vs. 1.027 ± 0.431 for Control) and monocyte chemoattractant protein (MCP)-1 (0.443 ± 0.201 for PAMB-G vs. 1.662 ± 0.912 for Control). In addition, PAMB-G had lower astrocyte and microglia numbers (35.75 ± 4.349 and 40.75 ± 7.890, respectively) compared to Control (50.75 ± 6.5 and 64.75 ± 10.72) and Gelatin (48.75 ± 4.787 and 71.75 ± 7.411). PAMB-G-treated rats also had significantly greater preservation and regeneration of remaining intact neuronal tissue (0.523 ± 0.059% mean white matter in PAMB-G vs 0.377 ± 0.044% in Control and 0.385 ± 0.051% in Gelatin) caused by reduced apoptosis and increased neuronal growth-associated gene expression. All these processes stemmed from PAMB-G facilitating increased electrical signaling conduction, leading to locomotive functional improvements, in the form of increased Basso-Beattie-Bresnahan scores and steeper angles in the slope test (76.667 ± 5.164 for PAMB-G, vs. 59.167 ± 4.916 for Control and 58.333 ± 4.082 for Gelatin), as well as reduced gastrocnemius muscle atrophy (0.345 ± 0.085 for PAMB-G, vs. 0.244 ± 0.021 for Control and 0.210 ± 0.058 for Gelatin). In conclusion, PAMB-G injection post-SCI resulted in improved electrical signaling conduction, which contributed to lowered inflammation and apoptosis, increased neuronal growth, and greater bodily functional control, suggesting its potential as a viable treatment for SCI.
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Affiliation(s)
- Yichong Zhang
- Department of Orthopedics and Trauma, Key Laboratory of Trauma and Neural Regeneration (Ministry of Education/Peking University), Peking University People's Hospital, Beijing, China
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada
| | - Alina Yao
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada
| | - Jun Wu
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada
| | - Shuhong Li
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada
| | - Minyao Wang
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada
| | - Zexu Peng
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada
| | - Hsing-Wen Sung
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan
| | - Baoguo Jiang
- Department of Orthopedics and Trauma, Key Laboratory of Trauma and Neural Regeneration (Ministry of Education/Peking University), Peking University People's Hospital, Beijing, China
| | - Ren-Ke Li
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada
- Division of Cardiovascular Surgery, Department of Surgery, University of Toronto, Toronto, Canada
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3
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Dagher M, Alayoubi M, Sigal GH, Cahill CM. Unveiling the link between chronic pain and misuse of opioids and cannabis. J Neural Transm (Vienna) 2024; 131:563-580. [PMID: 38570361 DOI: 10.1007/s00702-024-02765-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 03/10/2024] [Indexed: 04/05/2024]
Abstract
Over 50 million Americans endure chronic pain where many do not receive adequate treatment and self-medicate to manage their pain by taking substances like opioids and cannabis. Research has shown high comorbidity between chronic pain and substance use disorders (SUD) and these disorders share many common neurobiological underpinnings, including hypodopaminergic transmission. Drugs commonly used for self-medication such as opioids and cannabis relieve emotional, bothersome components of pain as well as negative emotional affect that perpetuates misuse and increases the risk of progressing towards drug abuse. However, the causal effect between chronic pain and the development of SUDs has not been clearly established. In this review, we discuss evidence that affirms the proposition that chronic pain is a risk factor for the development of opioid and cannabis use disorders by outlining the clinical evidence and detailing neurobiological mechanisms that link pain and drug misuse. Central to the link between chronic pain and opioid and cannabis misuse is hypodopaminergic transmission and the modulation of dopamine signaling in the mesolimbic pathway by opioids and cannabis. Moreover, we discuss the role of kappa opioid receptor activation and neuroinflammation in the context of dopamine transmission, their contribution to opioid and cannabis withdrawal, along with potential new treatments.
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Affiliation(s)
- Merel Dagher
- MacDonald Research Laboratory Building, Department of Psychiatry and Biobehavioral Sciences, Shirley and Stefan Hatos Center for Neuropharmacology, Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, 675 Charles E Young Drive South, Office 2774, Los Angeles, CA, 90095, USA
| | - Myra Alayoubi
- MacDonald Research Laboratory Building, Department of Psychiatry and Biobehavioral Sciences, Shirley and Stefan Hatos Center for Neuropharmacology, Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, 675 Charles E Young Drive South, Office 2774, Los Angeles, CA, 90095, USA
- Neuroscience Interdepartmental Program, University of California Los Angeles, Los Angeles, CA, 90095, USA
| | - Gabriella H Sigal
- Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, CA, 90095, USA
| | - Catherine M Cahill
- MacDonald Research Laboratory Building, Department of Psychiatry and Biobehavioral Sciences, Shirley and Stefan Hatos Center for Neuropharmacology, Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, 675 Charles E Young Drive South, Office 2774, Los Angeles, CA, 90095, USA.
- Neuroscience Interdepartmental Program, University of California Los Angeles, Los Angeles, CA, 90095, USA.
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4
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Wang R, Bai J. Pharmacological interventions targeting the microcirculation following traumatic spinal cord injury. Neural Regen Res 2024; 19:35-42. [PMID: 37488841 PMCID: PMC10479866 DOI: 10.4103/1673-5374.375304] [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: 11/06/2022] [Revised: 03/08/2023] [Accepted: 04/07/2023] [Indexed: 07/26/2023] Open
Abstract
Traumatic spinal cord injury is a devastating disorder characterized by sensory, motor, and autonomic dysfunction that severely compromises an individual's ability to perform activities of daily living. These adverse outcomes are closely related to the complex mechanism of spinal cord injury, the limited regenerative capacity of central neurons, and the inhibitory environment formed by traumatic injury. Disruption to the microcirculation is an important pathophysiological mechanism of spinal cord injury. A number of therapeutic agents have been shown to improve the injury environment, mitigate secondary damage, and/or promote regeneration and repair. Among them, the spinal cord microcirculation has become an important target for the treatment of spinal cord injury. Drug interventions targeting the microcirculation can improve the microenvironment and promote recovery following spinal cord injury. These drugs target the structure and function of the spinal cord microcirculation and are essential for maintaining the normal function of spinal neurons, axons, and glial cells. This review discusses the pathophysiological role of spinal cord microcirculation in spinal cord injury, including its structure and histopathological changes. Further, it summarizes the progress of drug therapies targeting the spinal cord microcirculation after spinal cord injury.
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Affiliation(s)
- Rongrong Wang
- Department of Spine and Spinal Cord Surgery, Beijing Bo’ai Hospital, China Rehabilitation Research Center, Beijing, China
- School of Rehabilitation Medicine, Capital Medical University, Beijing, China
| | - Jinzhu Bai
- Department of Spine and Spinal Cord Surgery, Beijing Bo’ai Hospital, China Rehabilitation Research Center, Beijing, China
- School of Rehabilitation Medicine, Capital Medical University, Beijing, China
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5
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Saghafi M, Danesh E, Askari R, Mousavi Z, Haghparast A. Differential Roles of the D1- and D2-Like Dopamine Receptors Within the Ventral Tegmental Area in Modulating the Antinociception Induced by Forced Swim Stress in the Rat. Neurochem Res 2024; 49:143-156. [PMID: 37642894 DOI: 10.1007/s11064-023-04017-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 08/05/2023] [Accepted: 08/15/2023] [Indexed: 08/31/2023]
Abstract
Several preclinical and clinical studies indicate that exposure to acute stress may decrease pain perception and increases pain tolerance. This phenomenon is called stress-induced analgesia (SIA). A variety of neurotransmitters, including dopamine, is involved in the SIA. Dopaminergic neurons in the mesolimbic circuits, originating from the ventral tegmental area (VTA), play a crucial role in various motivational, rewarding, and pain events. The present study aimed to investigate the modulatory role of VTA dopaminergic receptors in the antinociceptive responses evoked by forced swim stress (FSS) in a model of acute pain. One hundred-five adult male albino Wistar rats were subjected to stereotaxic surgery for implanting a unilateral cannula into the VTA. After one week of recovery, separate groups of animals were given different doses of SCH23390 and Sulpiride (0.25, 1, and 4 µg/0.3 µl) as D1- and D2-like receptor antagonists into the VTA, respectively. Then, the animals were exposed to FSS for a 6-min period, and the pain threshold was measured using the tail-flick test over a 60-min time set intervals. Results indicated that exposure to FSS produces a prominent antinociceptive response, diminishing by blocking both dopamine receptors in the VTA. Nonetheless, the effect of a D1-like dopamine receptor antagonist on FSS-induced analgesia was more prominent than that of a D2-like dopamine receptor antagonist. The results demonstrated that VTA dopaminergic receptors contribute to the pain process in stressful situations, and it might be provided a practical approach to designing new therapeutic agents for pain management.
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Affiliation(s)
- Mohammad Saghafi
- Pharmacology and Toxicology Department, Faculty of Pharmacy and Pharmaceutical Sciences, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | - Elaheh Danesh
- Neuroscience Research Center, School of Medicine, Shahid Beheshti University of Medical Sciences, P.O.Box: 19615-1178, Tehran, Iran
| | - Reyhaneh Askari
- Neuroscience Research Center, School of Medicine, Shahid Beheshti University of Medical Sciences, P.O.Box: 19615-1178, Tehran, Iran
| | - Zahra Mousavi
- Pharmacology and Toxicology Department, Faculty of Pharmacy and Pharmaceutical Sciences, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | - Abbas Haghparast
- Neuroscience Research Center, School of Medicine, Shahid Beheshti University of Medical Sciences, P.O.Box: 19615-1178, Tehran, Iran.
- School of Cognitive Sciences, Institute for Research in Fundamental Sciences, Tehran, Iran.
- Department of Basic Sciences, Iranian Academy of Medical Sciences, Tehran, Iran.
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6
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Lançon K, Séguéla P. Dysregulated neuromodulation in the anterior cingulate cortex in chronic pain. Front Pharmacol 2023; 14:1289218. [PMID: 37954846 PMCID: PMC10634228 DOI: 10.3389/fphar.2023.1289218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 10/09/2023] [Indexed: 11/14/2023] Open
Abstract
Chronic pain is a significant global socioeconomic burden with limited long-term treatment options. The intractable nature of chronic pain stems from two primary factors: the multifaceted nature of pain itself and an insufficient understanding of the diverse physiological mechanisms that underlie its initiation and maintenance, in both the peripheral and central nervous systems. The development of novel non-opioidergic analgesic approaches is contingent on our ability to normalize the dysregulated nociceptive pathways involved in pathological pain processing. The anterior cingulate cortex (ACC) stands out due to its involvement in top-down modulation of pain perception, its abnormal activity in chronic pain conditions, and its contribution to cognitive functions frequently impaired in chronic pain states. Here, we review the roles of the monoamines dopamine (DA), norepinephrine (NE), serotonin (5-HT), and other neuromodulators in controlling the activity of the ACC and how chronic pain alters their signaling in ACC circuits to promote pathological hyperexcitability. Additionally, we discuss the potential of targeting these monoaminergic pathways as a therapeutic strategy for treating the cognitive and affective symptoms associated with chronic pain.
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Affiliation(s)
| | - Philippe Séguéla
- Department of Neurology and Neurosurgery, Alan Edwards Centre for Research on Pain, Montréal Neurological Institute, McGill University, Montréal, QC, Canada
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7
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Barker DJ, Zhang S, Wang H, Estrin DJ, Miranda-Barrientos J, Liu B, Kulkarni RJ, de Deus JL, Morales M. Lateral preoptic area glutamate neurons relay nociceptive information to the ventral tegmental area. Cell Rep 2023; 42:113029. [PMID: 37632750 PMCID: PMC10584074 DOI: 10.1016/j.celrep.2023.113029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 04/28/2023] [Accepted: 08/09/2023] [Indexed: 08/28/2023] Open
Abstract
The ventral tegmental area (VTA) has been proposed to play a role in pain, but the brain structures modulating VTA activity in response to nociceptive stimuli remain unclear. Here, we demonstrate that the lateral preoptic area (LPO) glutamate neurons relay nociceptive information to the VTA. These LPO glutamatergic neurons synapsing on VTA neurons respond to nociceptive stimulation and conditioned stimuli predicting nociceptive stimulation and also mediate aversion. In contrast, LPO GABA neurons synapsing in the VTA mediate reward. By ultrastructural quantitative synaptic analysis, ex vivo electrophysiology, and functional neuroanatomy we identify a complex circuitry between LPO glutamatergic and GABAergic neurons and VTA dopaminergic, GABAergic, and glutamatergic neurons. We conclude that LPO glutamatergic neurons play a causal role in the processing of nociceptive stimuli and in relaying information about nociceptive stimuli. The pathway from LPO glutamatergic neurons to the VTA represents an unpredicted interface between peripheral nociceptive information and the limbic system.
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Affiliation(s)
- David J Barker
- Integrative Neuroscience Branch, Neuronal Networks Section, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD 21224, USA
| | - Shiliang Zhang
- Confocal and Electron Microscopy Core, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD 21224, USA
| | - Huiling Wang
- Integrative Neuroscience Branch, Neuronal Networks Section, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD 21224, USA
| | - David J Estrin
- Integrative Neuroscience Branch, Neuronal Networks Section, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD 21224, USA
| | - Jorge Miranda-Barrientos
- Integrative Neuroscience Branch, Neuronal Networks Section, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD 21224, USA
| | - Bing Liu
- Integrative Neuroscience Branch, Neuronal Networks Section, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD 21224, USA
| | - Rucha J Kulkarni
- Integrative Neuroscience Branch, Neuronal Networks Section, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD 21224, USA
| | - Junia Lara de Deus
- Integrative Neuroscience Branch, Neuronal Networks Section, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD 21224, USA
| | - Marisela Morales
- Integrative Neuroscience Branch, Neuronal Networks Section, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD 21224, USA.
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8
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Su N, Cai P, Dou Z, Yin X, Xu H, He J, Li Z, Li C. Brain nuclei and neural circuits in neuropathic pain and brain modulation mechanisms of acupuncture: a review on animal-based experimental research. Front Neurosci 2023; 17:1243231. [PMID: 37712096 PMCID: PMC10498311 DOI: 10.3389/fnins.2023.1243231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 08/14/2023] [Indexed: 09/16/2023] Open
Abstract
Neuropathic pain (NP) is known to be associated with abnormal changes in specific brain regions, but the complex neural network behind it is vast and complex and lacks a systematic summary. With the help of various animal models of NP, a literature search on NP brain regions and circuits revealed that the related brain nuclei included the periaqueductal gray (PAG), lateral habenula (LHb), medial prefrontal cortex (mPFC), and anterior cingulate cortex (ACC); the related brain circuits included the PAG-LHb and mPFC-ACC. Moreover, acupuncture and injurious information can affect different brain regions and influence brain functions via multiple aspects to play an analgesic role and improve synaptic plasticity by regulating the morphology and structure of brain synapses and the expression of synapse-related proteins; maintain the balance of excitatory and inhibitory neurons by regulating the secretion of glutamate, γ-aminobutyric acid, 5-hydroxytryptamine, and other neurotransmitters and receptors in the brain tissues; inhibit the overactivation of glial cells and reduce the release of pro-inflammatory mediators such as interleukins to reduce neuroinflammation in brain regions; maintain homeostasis of glucose metabolism and regulate the metabolic connections in the brain; and play a role in analgesia through the mediation of signaling pathways and signal transduction molecules. These factors help to deepen the understanding of NP brain circuits and the brain mechanisms of acupuncture analgesia.
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Affiliation(s)
- Na Su
- First Clinical Medicine College, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Pingping Cai
- Department of Traditional Chinese Medicine, Shandong Provincial Hospital, Jinan, China
| | - Zhiqiang Dou
- College of Acupuncture and Moxibustion and Tuina, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Xiaoxue Yin
- Department of Science and Education, Shandong Academy of Chinese Medicine, Jinan, China
| | - Hongmin Xu
- Department of Gynecology, Laiwu Hospital of Traditional Chinese, Jinan, China
| | - Jing He
- First Clinical Medicine College, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Zhaofeng Li
- College of Acupuncture and Moxibustion and Tuina, Shandong University of Traditional Chinese Medicine, Jinan, China
- International Office, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Changzhong Li
- Department of Obstetrics and Gynecology, Shenzhen Hospital, Peking University, Shenzhen, China
- Department of Gynecology, Shandong Provincial Hospital, Jinan, China
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9
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Alemi M, Pereira AR, Cerqueira-Nunes M, Monteiro C, Galhardo V, Cardoso-Cruz H. Role of Glutamatergic Projections from Lateral Habenula to Ventral Tegmental Area in Inflammatory Pain-Related Spatial Working Memory Deficits. Biomedicines 2023; 11:biomedicines11030820. [PMID: 36979799 PMCID: PMC10045719 DOI: 10.3390/biomedicines11030820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 03/02/2023] [Accepted: 03/04/2023] [Indexed: 03/30/2023] Open
Abstract
The lateral habenula (LHb) and the ventral tegmental area (VTA), which form interconnected circuits, have important roles in the crucial control of sensory and cognitive motifs. Signaling in the LHb-VTA pathway can be exacerbated during pain conditions by a hyperactivity of LHb glutamatergic neurons to inhibit local VTA DAergic cells. However, it is still unclear whether and how this circuit is endogenously engaged in pain-related cognitive dysfunctions. To answer this question, we modulated this pathway by expressing halorhodopsin in LHb neurons of adult male rats, and then selectively inhibited the axonal projections from these neurons to the VTA during a working memory (WM) task. Behavioral performance was assessed after the onset of an inflammatory pain model. We evaluated the impact of the inflammatory pain in the VTA synapses by performing immunohistochemical characterization of specific markers for GABAergic (GAD65/67) and dopaminergic neurons (dopamine transporter (DAT), dopamine D2 receptor (D2r) and tyrosine hydroxylase (TH)). Our results revealed that inhibition of LHb terminals in the VTA during the WM delay-period elicits a partial recovery of the performance of pain animals (in higher complexity challenges); this performance was not accompanied by a reduction of nociceptive responses. Finally, we found evidence that the pain-affected animals exhibit VTA structural changes, namely with an upregulation of GAD65/67, and a downregulation of DAT and D2r. These results demonstrate a role of LHb neurons and highlight their responsibility in the stability of the local VTA network, which regulates signaling in frontal areas necessary to support WM processes.
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Affiliation(s)
- Mobina Alemi
- Instituto de Investigação e Inovação em Saúde-Pain Neurobiology Group, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
- Faculdade de Medicina, Departamento de Biomedicina-Unidade de Biologia Experimental, Universidade do Porto, Rua Doutor Plácido da Costa, 4200-450 Porto, Portugal
| | - Ana Raquel Pereira
- Instituto de Investigação e Inovação em Saúde-Pain Neurobiology Group, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
- Faculdade de Medicina, Departamento de Biomedicina-Unidade de Biologia Experimental, Universidade do Porto, Rua Doutor Plácido da Costa, 4200-450 Porto, Portugal
| | - Mariana Cerqueira-Nunes
- Instituto de Investigação e Inovação em Saúde-Pain Neurobiology Group, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
- Faculdade de Medicina, Departamento de Biomedicina-Unidade de Biologia Experimental, Universidade do Porto, Rua Doutor Plácido da Costa, 4200-450 Porto, Portugal
- Programa Doutoral em Neurociências, Faculdade de Medicina, Universidade do Porto, Rua Doutor Plácido da Costa, 4200-450 Porto, Portugal
| | - Clara Monteiro
- Instituto de Investigação e Inovação em Saúde-Pain Neurobiology Group, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
- Faculdade de Medicina, Departamento de Biomedicina-Unidade de Biologia Experimental, Universidade do Porto, Rua Doutor Plácido da Costa, 4200-450 Porto, Portugal
| | - Vasco Galhardo
- Instituto de Investigação e Inovação em Saúde-Pain Neurobiology Group, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
- Faculdade de Medicina, Departamento de Biomedicina-Unidade de Biologia Experimental, Universidade do Porto, Rua Doutor Plácido da Costa, 4200-450 Porto, Portugal
| | - Helder Cardoso-Cruz
- Instituto de Investigação e Inovação em Saúde-Pain Neurobiology Group, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
- Faculdade de Medicina, Departamento de Biomedicina-Unidade de Biologia Experimental, Universidade do Porto, Rua Doutor Plácido da Costa, 4200-450 Porto, Portugal
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10
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Wang BG, Xu LL, Yang HY, Xie J, Xu G, Tang WC. Manual acupuncture for neuromusculoskeletal disorders: The selection of stimulation parameters and corresponding effects. Front Neurosci 2023; 17:1096339. [PMID: 36793537 PMCID: PMC9922711 DOI: 10.3389/fnins.2023.1096339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Accepted: 01/11/2023] [Indexed: 01/31/2023] Open
Abstract
As a minimally invasive method of physical stimulation, manual acupuncture (MA) is used globally as a sort of therapy for neuromusculoskeletal disorders. In addition to selecting appropriate acupoints, acupuncturists should also determine the stimulation parameters of needling, such as the manipulation (lifting-thrusting or twirling), needling amplitude, velocity, and stimulation time. At present, most studies focus on acupoint combination and mechanism of MA, the relationship between stimulation parameters and their therapeutic effects, as well as the influence on mechanism of action are relatively scattered, and lack of systematic summary and analysis. This paper reviewed the three types of stimulation parameters of MA, their common options and values, corresponding effects and potential mechanisms of action. The purpose of such efforts is to provide a useful reference for the dose-effect relationship of MA and the quantification and standardization of its clinical treatment of neuromusculoskeletal disorders to further promote the application of acupuncture in the world.
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Affiliation(s)
- Bing-Gan Wang
- School of Acupuncture-Moxibustion and Tuina, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Liu-Liu Xu
- School of Acupuncture-Moxibustion and Tuina, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Hua-Yuan Yang
- School of Acupuncture-Moxibustion and Tuina, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Jian Xie
- Department of Acupuncture and Moxibustion, Yuhuan Hospital of Traditional Chinese Medicine, Taizhou, Zhejiang, China
| | - Gang Xu
- School of Acupuncture-Moxibustion and Tuina, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Wen-Chao Tang
- School of Acupuncture-Moxibustion and Tuina, Shanghai University of Traditional Chinese Medicine, Shanghai, China
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Benarroch E. What Are the Interactions Between the Midbrain Dopamine System in Pain? Neurology 2022; 98:274-278. [PMID: 35165154 DOI: 10.1212/wnl.0000000000013253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 12/02/2021] [Indexed: 11/15/2022] Open
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12
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Lançon K, Qu C, Navratilova E, Porreca F, Séguéla P. Decreased dopaminergic inhibition of pyramidal neurons in anterior cingulate cortex maintains chronic neuropathic pain. Cell Rep 2021; 37:109933. [PMID: 34852233 PMCID: PMC8728690 DOI: 10.1016/j.celrep.2021.109933] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 07/02/2021] [Accepted: 10/13/2021] [Indexed: 12/20/2022] Open
Abstract
Pyramidal neurons in the anterior cingulate cortex (ACC), a prefrontal region involved in processing the affective components of pain, display hyperexcitability in chronic neuropathic pain conditions, and their silencing abolishes hyperalgesia. We show that dopamine, through D1 receptor (D1R) signaling, inhibits pyramidal neurons of mouse ACC by modulation of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. Activation of Gs-coupled D1R by dopamine induces the opening of HCN channels at physiological membrane potentials, driving a significant decrease in input resistance and excitability. Systemic L-DOPA in chronic neuropathic mice rescues HCN channel activity, normalizes pyramidal excitability in ACC, and blocks mechanical and thermal allodynia. Moreover, microinjection of a selective D1R agonist in the ACC relieves the aversiveness of ongoing neuropathic pain, while an ACC D1R antagonist blocks gabapentin- and lidocaine-evoked antinociception. We conclude that dopaminergic inhibition via D1R in ACC plays an analgesic role in physiological conditions and is decreased in chronic pain.
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Affiliation(s)
- Kevin Lançon
- Montréal Neurological Institute, Department of Neurology & Neurosurgery, Alan Edwards Centre for Research on Pain, McGill University, Montréal, QC H3A 2B4, Canada
| | - Chaoling Qu
- Department of Pharmacology, Arizona Health Sciences Center, University of Arizona, Tucson, AZ 85721, USA
| | - Edita Navratilova
- Department of Pharmacology, Arizona Health Sciences Center, University of Arizona, Tucson, AZ 85721, USA
| | - Frank Porreca
- Department of Pharmacology, Arizona Health Sciences Center, University of Arizona, Tucson, AZ 85721, USA
| | - Philippe Séguéla
- Montréal Neurological Institute, Department of Neurology & Neurosurgery, Alan Edwards Centre for Research on Pain, McGill University, Montréal, QC H3A 2B4, Canada.
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Ghasemzadeh Z, Seddighfar M, Alijanpour S, Rezayof A. Ventral tegmental area serotonin 5-HT 1A receptors and corticolimbic cFos/BDNF/GFAP signaling pathways mediate dextromethorphan/morphine anti-allodynia. Physiol Behav 2021; 239:113522. [PMID: 34242672 DOI: 10.1016/j.physbeh.2021.113522] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 06/10/2021] [Accepted: 06/30/2021] [Indexed: 12/30/2022]
Abstract
AIMS The present study examined the role of ventral tegmental area (VTA) serotonergic 5HT1A receptors in dextromethorphan/morphine-induced anti-allodynia and the possible changes of corticolimbic cFos, brain-derived neurotrophic factor (BDNF), and glial fibrillary acidic protein (GFAP) following the treatments. MATERIALS AND METHODS The VTA cannulation and the chronic constriction of the sciatic nerve were performed in male Wistar rats. Flexion withdrawal thresholds to mechanical stimulation in the hind-limb were determined using von Frey hairs. The expressions of cFos, BDNF, and GFAP were evaluated using the Western blotting technique. KEY FINDINGS BDNF (in the hippocampus), and GFAP (in the targeted sites) levels were increased following neuropathic pain. Morphine administration induced an anti-allodynic effect with a decrease in the amygdala BDNF level. Dextromethorphan/morphine-induced anti-allodynia was accompanied by the decrease of hippocampus/amygdala/PFC GFAP and amygdala cFos expressions. The PFC BDNF expression level was increased in dextromethorphan/morphine-treated rats. Intra-VTA microinjection of (S)-WAY100135 (1 µg/rat), a selective 5-HT1A receptor antagonist, inhibited the anti-allodynic effect of dextromethorphan/morphine. This treatment increased the cFos level in the hippocampus and the amygdala while decreased the PFC level of cFos. The hippocampal BDNF expression was significantly increased, while the amygdala and the PFC expressions of BDNF were decreased under treatment. (S)-WAY100135 plus dextromethorphan/morphine increased the hippocampal/amygdala and PFC levels of GFAP. SIGNIFICANCE These findings indicate that dextromethorphan could potentiate the analgesic effect of morphine via the implication of the VTA serotonin 5-HT1A receptors. It seems that the changes in the corticolimbic cFos/BDNF/GFAP signaling pathway may be involved in the observed anti-allodynic effect.
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Affiliation(s)
- Zahra Ghasemzadeh
- Department of Animal Biology, School of Biology, College of Science, University of Tehran, Tehran, Iran
| | - Masoud Seddighfar
- Department of Animal Biology, School of Biology, College of Science, University of Tehran, Tehran, Iran
| | - Sakineh Alijanpour
- Department of Biology, Faculty of Science, Gonbad Kavous University, Gonbad Kavous, Iran
| | - Ameneh Rezayof
- Department of Animal Biology, School of Biology, College of Science, University of Tehran, Tehran, Iran.
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Reactivating a positive feedback loop VTA-BLA-NAc circuit associated with positive experience ameliorates the attenuated reward sensitivity induced by chronic stress. Neurobiol Stress 2021; 15:100370. [PMID: 34381852 PMCID: PMC8334743 DOI: 10.1016/j.ynstr.2021.100370] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 07/20/2021] [Accepted: 07/22/2021] [Indexed: 12/24/2022] Open
Abstract
Both genetic predisposition and life events, particularly life stress, are thought to increase the risk for depression. Reward sensitivity appears to be attenuated in major depressive disorder (MDD), suggesting deficits in reward processing in these patients. We identified the VTA-BLA-NAc circuit as being activated by sex reward, and the VTA neurons that respond to sex reward are mostly dopaminergic. Acute or chronic reactivation of this circuit ameliorates the reward insensitivity induced by chronic restraint stress. Our histological and electrophysiological results show that the VTA neuron subpopulation responding to restraint stress, predominantly GABAergic neurons, inhibits the responsiveness of VTA dopaminergic neurons to reward stimuli, which is probably the mechanism by which stress modulates the reward processing neural circuits and subsequently disrupts reward-related behaviours. Furthermore, we found that the VTA-BLA-NAc circuit is a positive feedback loop. Blocking the projections from the BLA to the NAc associated with sex reward increases the excitability of VTA GABAergic neurons and decreases the excitability of VTA dopaminergic neurons, while activating this pathway decreases the excitability of VTA GABAergic neurons and increases the excitability of VTA dopaminergic neurons, which may be the cellular mechanism by which the VTA-BLA-NAc circuit associated with sex reward ameliorates the attenuated reward sensitivity induced by chronic stress.
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15
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Li X, Wang Q, Ding J, Wang S, Dong C, Wu Q. Exercise training modulates glutamic acid decarboxylase-65/67 expression through TrkB signaling to ameliorate neuropathic pain in rats with spinal cord injury. Mol Pain 2021; 16:1744806920924511. [PMID: 32418502 PMCID: PMC7235678 DOI: 10.1177/1744806920924511] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Neuropathic pain is one of the most frequently stated complications after spinal cord injury. In post-spinal cord injury, the decrease of gamma aminobutyric acid synthesis within the distal spinal cord is one of the main causes of neuropathic pain. The predominant research question of this study was whether exercise training may promote the expression of glutamic acid decarboxylase-65 and glutamic acid decarboxylase-67, which are key enzymes of gamma aminobutyric acid synthesis, within the distal spinal cord through tropomyosin-related kinase B signaling, as its synthesis assists to relieve neuropathic pain after spinal cord injury. Animal experiment was conducted, and all rats were allocated into five groups: Sham group, SCI/PBS group, SCI-TT/PBS group, SCI/tropomyosin-related kinase B-IgG group, and SCI-TT/tropomyosin-related kinase B-IgG group, and then T10 contusion SCI model was performed as well as the tropomyosin-related kinase B-IgG was used to block the tropomyosin-related kinase B activation. Mechanical withdrawal thresholds and thermal withdrawal latencies were used for assessing pain-related behaviors. Western blot analysis was used to detect the expression of brain-derived neurotrophic factor, tropomyosin-related kinase B, CREB, p-REB, glutamic acid decarboxylase-65, and glutamic acid decarboxylase-67 within the distal spinal cord. Immunohistochemistry was used to analyze the distribution of CREB, p-CREB, glutamic acid decarboxylase-65, and glutamic acid decarboxylase-67 within the distal spinal cord dorsal horn. The results showed that exercise training could significantly mitigate the mechanical allodynia and thermal hyperalgesia in post-spinal cord injury and increase the synthesis of brain-derived neurotrophic factor, tropomyosin-related kinase B, CREB, p-CREB, glutamic acid decarboxylase-65, and glutamic acid decarboxylase-67 within the distal spinal cord. After the tropomyosin-related kinase B signaling was blocked, the analgesic effect of exercise training was inhibited, and in the SCI-TT/tropomyosin-related kinase B-IgG group, the synthesis of CREB, p-CREB, glutamic acid decarboxylase-65, and glutamic acid decarboxylase-67 within the distal spinal cord were also significantly reduced compared with the SCI-TT/PBS group. This study shows that exercise training may increase the glutamic acid decarboxylase-65 and glutamic acid decarboxylase-67 expression within the spinal cord dorsal horn through the tropomyosin-related kinase B signaling, and this mechanism may play a vital role in relieving the neuropathic pain of rats caused by incomplete SCI.
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Affiliation(s)
- Xiangzhe Li
- Rehabilitation Medical Center, the Affiliated Suzhou Science & Technology Town Hospital of Nanjing Medical University, Suzhou, Jiangsu, People's Republic of China
| | - Qinghua Wang
- Laboratory Animal Center, Nantong University, Nantong, Jiangsu, People's Republic of China
| | - Jie Ding
- Departments of Respiratory Care, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Sheng Wang
- Rehabilitation Medical Center, the Affiliated Suzhou Science & Technology Town Hospital of Nanjing Medical University, Suzhou, Jiangsu, People's Republic of China
| | - Chuanming Dong
- Department of Anatomy, Medical College of Nantong University, Nantong, Jiangsu, People's Republic of China
| | - Qinfeng Wu
- Rehabilitation Medical Center, the Affiliated Suzhou Science & Technology Town Hospital of Nanjing Medical University, Suzhou, Jiangsu, People's Republic of China
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16
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Zhang Y, Al Mamun A, Yuan Y, Lu Q, Xiong J, Yang S, Wu C, Wu Y, Wang J. Acute spinal cord injury: Pathophysiology and pharmacological intervention (Review). Mol Med Rep 2021; 23:417. [PMID: 33846780 PMCID: PMC8025476 DOI: 10.3892/mmr.2021.12056] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 11/12/2020] [Indexed: 12/12/2022] Open
Abstract
Spinal cord injury (SCI) is one of the most debilitating of all the traumatic conditions that afflict individuals. For a number of years, extensive studies have been conducted to clarify the molecular mechanisms of SCI. Experimental and clinical studies have indicated that two phases, primary damage and secondary damage, are involved in SCI. The initial mechanical damage is caused by local impairment of the spinal cord. In addition, the fundamental mechanisms are associated with hyperflexion, hyperextension, axial loading and rotation. By contrast, secondary injury mechanisms are led by systemic and cellular factors, which may also be initiated by the primary injury. Although significant advances in supportive care have improved clinical outcomes in recent years, a number of studies continue to explore specific pharmacological therapies to minimize SCI. The present review summarized some important pathophysiologic mechanisms that are involved in SCI and focused on several pharmacological and non‑pharmacological therapies, which have either been previously investigated or have a potential in the management of this debilitating injury in the near future.
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Affiliation(s)
- Yi Zhang
- School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094, P.R. China
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, P.R. China
| | - Abdullah Al Mamun
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, P.R. China
| | - Yuan Yuan
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, P.R. China
| | - Qi Lu
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, P.R. China
| | - Jun Xiong
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, P.R. China
| | - Shulin Yang
- School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094, P.R. China
| | - Chengbiao Wu
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, P.R. China
| | - Yanqing Wu
- Institute of Life Sciences, Wenzhou University, Wenzhou, Zhejiang 325035, P.R. China
| | - Jian Wang
- Department of Hand Surgery and Peripheral Neurosurgery, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325035, P.R. China
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Fisher AS, Lanigan MT, Upton N, Lione LA. Preclinical Neuropathic Pain Assessment; the Importance of Translatability and Bidirectional Research. Front Pharmacol 2021; 11:614990. [PMID: 33628181 PMCID: PMC7897667 DOI: 10.3389/fphar.2020.614990] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 12/10/2020] [Indexed: 02/04/2023] Open
Abstract
For patients suffering with chronic neuropathic pain the need for suitable novel therapies is imperative. Over recent years a contributing factor for the lack of development of new analgesics for neuropathic pain has been the mismatch of primary neuropathic pain assessment endpoints in preclinical vs. clinical trials. Despite continuous forward translation failures across diverse mechanisms, reflexive quantitative sensory testing remains the primary assessment endpoint for neuropathic pain and analgesia in animals. Restricting preclinical evaluation of pain and analgesia to exclusively reflexive outcomes is over simplified and can be argued not clinically relevant due to the continued lack of forward translation and failures in the clinic. The key to developing new analgesic treatments for neuropathic pain therefore lies in the development of clinically relevant endpoints that can translate preclinical animal results to human clinical trials. In this review we discuss this mismatch of primary neuropathic pain assessment endpoints, together with clinical and preclinical evidence that supports how bidirectional research is helping to validate new clinically relevant neuropathic pain assessment endpoints. Ethological behavioral endpoints such as burrowing and facial grimacing and objective measures such as electroencephalography provide improved translatability potential together with currently used quantitative sensory testing endpoints. By tailoring objective and subjective measures of neuropathic pain the translatability of new medicines for patients suffering with neuropathic pain will hopefully be improved.
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Affiliation(s)
- Amy S Fisher
- Transpharmation Ltd., The London Bioscience Innovation Centre, London, United Kingdom
| | - Michael T Lanigan
- Transpharmation Ltd., The London Bioscience Innovation Centre, London, United Kingdom.,School of Life and Medical Sciences, University of Hertfordshire, Hatfield, United Kingdom
| | - Neil Upton
- Transpharmation Ltd., The London Bioscience Innovation Centre, London, United Kingdom
| | - Lisa A Lione
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, United Kingdom
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18
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Alterations of Dopamine-Related Transcripts in A11 Diencephalospinal Pathways after Spinal Cord Injury. Neural Plast 2021; 2021:8838932. [PMID: 33510781 PMCID: PMC7822663 DOI: 10.1155/2021/8838932] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 12/04/2020] [Accepted: 01/05/2021] [Indexed: 12/15/2022] Open
Abstract
The diencephalic A11 nuclei are the primary source of spinal dopamine (DA). Neurons in this region project to all levels of the spinal cord. Traumatic spinal cord injury (SCI) often interrupts descending and ascending neuronal pathways and further elicits injury-induced neuronal plasticity. However, it is unknown how A11 neurons and projections respond to SCI-induced axotomy. Based on preliminary observation, we hypothesized that A11 DA-ergic neurons rostral to the lesion site might change their capacity to synthesize DA after SCI. Adult rats received a complete spinal cord transection at the 10th thoracic (T10) level. After 3 or 8 weeks, rostral (T5) and caudal (L1) spinal cord tissue was collected to measure mRNA levels of DA-related genes. Meanwhile, A11 neurons in the brain were explicitly isolated by laser capture microdissection, and single-cell qPCR was employed to evaluate mRNA levels in the soma. Histological analysis was conducted to assess the number of A11 DA-ergic neurons. The results showed that, compared to naïve rats, mRNA levels of tyrosine hydroxylase (TH), dopamine decarboxylase (DDC), and D2 receptors in the T5 spinal segment had a transient decrease and subsequent recovery. However, dopamine-β-hydroxylase (DBH), D1 receptors, and DA-associated transcription factors did not change following SCI. Furthermore, axon degeneration below the lesion substantially reduced mRNA levels of TH and D2 in the L1 spinal segment. However, DDC transcript underwent only a temporary decrease. Similar mRNA levels of DA-related enzymes were detected in the A11 neuronal soma between naïve and SCI rats. In addition, immunostaining revealed that the number of A11 DA neurons did not change after SCI, indicating a sustention of capacity to synthesize DA in the neuroplasm. Thus, impaired A11 diencephalospinal pathways following SCI may transiently reduce DA production in the spinal cord rostral to the lesion but not in the brain.
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19
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O'Reilly ML, Tom VJ. Neuroimmune System as a Driving Force for Plasticity Following CNS Injury. Front Cell Neurosci 2020; 14:187. [PMID: 32792908 PMCID: PMC7390932 DOI: 10.3389/fncel.2020.00187] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 05/29/2020] [Indexed: 12/15/2022] Open
Abstract
Following an injury to the central nervous system (CNS), spontaneous plasticity is observed throughout the neuraxis and affects multiple key circuits. Much of this spontaneous plasticity can elicit beneficial and deleterious functional outcomes, depending on the context of plasticity and circuit affected. Injury-induced activation of the neuroimmune system has been proposed to be a major factor in driving this plasticity, as neuroimmune and inflammatory factors have been shown to influence cellular, synaptic, structural, and anatomical plasticity. Here, we will review the mechanisms through which the neuroimmune system mediates plasticity after CNS injury. Understanding the role of specific neuroimmune factors in driving adaptive and maladaptive plasticity may offer valuable therapeutic insight into how to promote adaptive plasticity and/or diminish maladaptive plasticity, respectively.
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Affiliation(s)
- Micaela L O'Reilly
- Department of Neurobiology and Anatomy, Marion Murray Spinal Cord Research Center, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Veronica J Tom
- Department of Neurobiology and Anatomy, Marion Murray Spinal Cord Research Center, Drexel University College of Medicine, Philadelphia, PA, United States
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20
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Matini T, Haghparast A, Rezaee L, Salehi S, Tehranchi A, Haghparast A. Role of Dopaminergic Receptors Within the Ventral Tegmental Area in Antinociception Induced by Chemical Stimulation of the Lateral Hypothalamus in an Animal Model of Orofacial Pain. J Pain Res 2020; 13:1449-1460. [PMID: 32606911 PMCID: PMC7304680 DOI: 10.2147/jpr.s255250] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 06/03/2020] [Indexed: 12/13/2022] Open
Abstract
Introduction The ventral tegmental area (VTA), as one of the classical components of the brain reward circuitry, shares large neural networks with the pain processing system. We previously showed the role of VTA dopamine receptors in modulation of lateral hypothalamus (LH)-induced antinociception in acute pain conditions. However, considering the fact that the neural systems involved in the mediation of tonic pain are not the same as those that mediate phasic pain. In the present study, we aimed to examine the role of intra-VTA dopamine receptors in LH-induced antinociceptive responses during tonic orofacial pain conditions. Methods Male Wistar rats weighing 230-250 g were implanted with two separate cannulae into the LH and VTA on the same side. Different solutions of carbachol (62.5, 125 and 250 nM), as a non-selective cholinergic receptor agonist that activates the LH projecting neurons, were microinjected into the LH. In the other groups, D1-like dopamine receptor antagonist, SCH-23390 (0.25, 1 and 4 µg/03 µL saline) or D2-like dopamine receptor antagonist, Sulpiride (0.25, 1 and 4 µg/0.3 µL DMSO 12%) were microinjected into VTA, 5 min prior intra-LH carbachol (250 nM), then subjected to orofacial formalin test. Intra-LH carbachol microinjection dose-dependently attenuated biphasic orofacial pain. Results Intra-VTA administration of SCH-23390 or Sulpiride dose-dependently decreased intra-LH carbachol-induced antinociception during both phases of orofacial formalin test with further effects in the late phase. Discussion The findings suggest that chemical stimulation of the LH by carbachol possibly activates the orexin projecting neurons and subsequently, the VTA dopaminergic neurons involved in the orofacial pain modulation. Detecting such neural circuitry offers an alternative approach in the development of more efficient therapies for such debilitating pain conditions.
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Affiliation(s)
- Tina Matini
- School of Dentistry, International Branch of Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Amir Haghparast
- School of Dentistry, International Branch of Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Laleh Rezaee
- Neuroscience Research Center, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Sakineh Salehi
- Neuroscience Research Center, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.,Department of Medicine, Ardabil Medical Sciences Branch, Islamic Azad University, Ardabil, Iran
| | - Azita Tehranchi
- Dental Research Center, Research Institute of Dental Sciences, Dental School, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Abbas Haghparast
- Neuroscience Research Center, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Regional Hyperexcitability and Chronic Neuropathic Pain Following Spinal Cord Injury. Cell Mol Neurobiol 2020; 40:861-878. [PMID: 31955281 DOI: 10.1007/s10571-020-00785-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 01/02/2020] [Indexed: 12/15/2022]
Abstract
Spinal cord injury (SCI) causes maladaptive changes to nociceptive synaptic circuits within the injured spinal cord. Changes also occur at remote regions including the brain stem, limbic system, cortex, and dorsal root ganglia. These maladaptive nociceptive synaptic circuits frequently cause neuronal hyperexcitability in the entire nervous system and enhance nociceptive transmission, resulting in chronic central neuropathic pain following SCI. The underlying mechanism of chronic neuropathic pain depends on the neuroanatomical structures and electrochemical communication between pre- and postsynaptic neuronal membranes, and propagation of synaptic transmission in the ascending pain pathways. In the nervous system, neurons are the only cell type that transmits nociceptive signals from peripheral receptors to supraspinal systems due to their neuroanatomical and electrophysiological properties. However, the entire range of nociceptive signaling is not mediated by any single neuron. Current literature describes regional studies of electrophysiological or neurochemical mechanisms for enhanced nociceptive transmission post-SCI, but few studies report the electrophysiological, neurochemical, and neuroanatomical changes across the entire nervous system following a regional SCI. We, along with others, have continuously described the enhanced nociceptive transmission in the spinal dorsal horn, brain stem, thalamus, and cortex in SCI-induced chronic central neuropathic pain condition, respectively. Thus, this review summarizes the current understanding of SCI-induced neuronal hyperexcitability and maladaptive nociceptive transmission in the entire nervous system that contributes to chronic central neuropathic pain.
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22
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Huang S, Borgland SL, Zamponi GW. Peripheral nerve injury-induced alterations in VTA neuron firing properties. Mol Brain 2019; 12:89. [PMID: 31685030 PMCID: PMC6827252 DOI: 10.1186/s13041-019-0511-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 10/10/2019] [Indexed: 11/28/2022] Open
Abstract
The ventral tegmental area (VTA) is one of the main brain regions harboring dopaminergic (DA) neurons, and plays important roles in reinforcement and motivation. Recent studies have indicated that DA neurons not only respond to rewarding stimuli, but also to noxious stimuli. Furthermore, VTA DA neurons undergo plasticity during chronic pain. Lateral and medial VTA neurons project to different brain areas, and have been characterized via their distinct electrophysiological properties. In this study, we characterized electrophysiological properties of lateral and medial VTA DA neurons using DAT-cre reporter mice, and examined their plasticity during neuropathic pain states. We observed various DA subpopulations in both the lateral and medial VTA, as defined by action potential firing patterns, independently of synaptic inputs. Our results demonstrated that lateral and medial VTA DA neurons undergo differential plasticity after peripheral nerve injury that leads to neuropathic pain. However, these changes only reside in specific DA subpopulations. This study suggests that lateral and medial VTA DA neurons are differentially affected during neuropathic pain conditions, and emphasizes the importance of subpopulation specificity when targeting VTA DA neurons for treatment of neuropathic pain.
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Affiliation(s)
- Shuo Huang
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Calgary, AB, Canada.,Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Stephanie L Borgland
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Calgary, AB, Canada
| | - Gerald W Zamponi
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Calgary, AB, Canada. .,Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.
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23
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Ge MM, Chen SP, Zhou YQ, Li Z, Tian XB, Gao F, Manyande A, Tian YK, Yang H. The therapeutic potential of GABA in neuron-glia interactions of cancer-induced bone pain. Eur J Pharmacol 2019; 858:172475. [DOI: 10.1016/j.ejphar.2019.172475] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 06/17/2019] [Accepted: 06/18/2019] [Indexed: 01/06/2023]
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24
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Knowing the Neuronal Mechanism of Spontaneous Pain to Treat Chronic Pain in the Future. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1099:115-124. [DOI: 10.1007/978-981-13-1756-9_10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
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