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Dedek C, Azadgoleh MA, Prescott SA. Reproducible and fully automated testing of nocifensive behavior in mice. CELL REPORTS METHODS 2023; 3:100650. [PMID: 37992707 PMCID: PMC10783627 DOI: 10.1016/j.crmeth.2023.100650] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 09/11/2023] [Accepted: 10/30/2023] [Indexed: 11/24/2023]
Abstract
Pain in rodents is often inferred from their withdrawal from noxious stimulation. Threshold stimulus intensity or response latency is used to quantify pain sensitivity. This usually involves applying stimuli by hand and measuring responses by eye, which limits reproducibility and throughput. We describe a device that standardizes and automates pain testing by providing computer-controlled aiming, stimulation, and response measurement. Optogenetic and thermal stimuli are applied using blue and infrared light, respectively. Precise mechanical stimulation is also demonstrated. Reflectance of red light is used to measure paw withdrawal with millisecond precision. We show that consistent stimulus delivery is crucial for resolving stimulus-dependent variations in withdrawal and for testing with sustained stimuli. Moreover, substage video reveals "spontaneous" behaviors for consideration alongside withdrawal metrics to better assess the pain experience. The entire process was automated using machine learning. RAMalgo (reproducible automated multimodal algometry) improves the standardization, comprehensiveness, and throughput of preclinical pain testing.
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Affiliation(s)
- Christopher Dedek
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada
| | - Mehdi A Azadgoleh
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Steven A Prescott
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.
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Hsiao IH, Liao HY, Lin YW. Optogenetic modulation of electroacupuncture analgesia in a mouse inflammatory pain model. Sci Rep 2022; 12:9067. [PMID: 35641558 PMCID: PMC9156770 DOI: 10.1038/s41598-022-12771-8] [Citation(s) in RCA: 8] [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: 01/12/2022] [Accepted: 04/22/2022] [Indexed: 11/09/2022] Open
Abstract
Peripheral tissue damage and associated inflammation can trigger neuroplastic changes in somatic pain pathways, such as reduced neuronal firing thresholds and synaptic potentiation, that ultimately lead to peripheral sensitization and chronic pain. Electroacupuncture (EA) can relieve chronic inflammatory pain, but the underlying mechanisms are unknown, including the contributions of higher pain centers such as somatosensory cortex (SSC). We investigated these mechanisms using optogenetic modulation of SSC activity in a mouse inflammatory pain model. Injection of Complete Freund's Adjuvant into the hind paw reliably induced inflammation accompanied by reduced mechanical and thermal pain thresholds (hyperalgesia) within three days (mechanical: 1.54 ± 0.13 g; thermal: 3.94 ± 0.43 s). Application of EA produced significant thermal and mechanical analgesia, but these responses were reversed by optogenetic activation of SSC neurons, suggesting that EA-induced analgesia involves modulation of central pain pathways. Western blot and immunostaining revealed that EA also attenuated CaMKIIα signaling in the dorsal root ganglion, central spinal cord, SSC, and anterior cingulate cortex (ACC). In contrast, optogenetic activation of the SSC induced CaMKIIα signaling in SSC and ACC. These findings suggest that AE can relieve inflammatory pain by suppressing CaMKIIα-dependent plasticity in cortical pain pathways. The SSC and ACC CaMKIIα signaling pathways may be valuable therapeutic targets for chronic inflammatory pain treatment.
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Affiliation(s)
- I-Han Hsiao
- College of Chinese Medicine, Graduate Institute of Acupuncture Science, China Medical University, 91 Hsueh-Shih Road, Taichung, 40402, Taiwan
- Department of Neurosurgery, China Medical University Hospital, Taichung, 404332, Taiwan
| | - Hsien-Yin Liao
- College of Chinese Medicine, School of Post-Baccalaureate Chinese Medicine, China Medical University, 91 Hsueh-Shih Road, Taichung, 40402, Taiwan.
| | - Yi-Wen Lin
- College of Chinese Medicine, Graduate Institute of Acupuncture Science, China Medical University, 91 Hsueh-Shih Road, Taichung, 40402, Taiwan.
- Chinese Medicine Research Center, China Medical University, Taichung, 40402, Taiwan.
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Isagulyan ED, Mikhailova VA, Aslakhanova KS, Slavin KV. Prospects of neuromodulation for chronic pain. BRAIN DISORDERS 2022. [DOI: 10.1016/j.dscb.2021.100027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Genaro K, Prado WA. The role of the anterior pretectal nucleus in pain modulation: A comprehensive review. Eur J Neurosci 2021; 54:4358-4380. [PMID: 33909941 DOI: 10.1111/ejn.15255] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 04/16/2021] [Accepted: 04/18/2021] [Indexed: 11/27/2022]
Abstract
Descending pain modulation involves multiple encephalic sites and pathways that range from the cerebral cortex to the spinal cord. Behavioral studies conducted in the 1980s revealed that electrical stimulation of the pretectal area causes antinociception dissociation from aversive responses. Anatomical and physiological studies identified the anterior pretectal nucleus and its descending projections to several midbrain, pontine, and medullary structures. The anterior pretectal nucleus is morphologically divided into a dorsal part that contains a dense neuron population (pars compacta) and a ventral part that contains a dense fiber band network (pars reticulata). Connections of the two anterior pretectal nucleus parts are broad and include prominent projections to and from major encephalic systems associated with somatosensory processes. Since the first observation that acute or chronic noxious stimuli activate the anterior pretectal nucleus, it has been established that numerous mediators participate in this response through distinct pathways. Recent studies have confirmed that at least two pain inhibitory pathways are activated from the anterior pretectal nucleus. This review focuses on rodent anatomical, behavioral, molecular, and neurochemical data that have helped to identify mediators of the anterior pretectal nucleus and pathways related to its role in pain modulation.
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Affiliation(s)
- Karina Genaro
- Department of Anesthesiology, University of California, Irvine, CA, USA
| | - Wiliam A Prado
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
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Spinal Excitatory Dynorphinergic Interneurons Contribute to Burn Injury-Induced Nociception Mediated by Phosphorylated Histone 3 at Serine 10 in Rodents. Int J Mol Sci 2021; 22:ijms22052297. [PMID: 33669046 PMCID: PMC7956488 DOI: 10.3390/ijms22052297] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 02/20/2021] [Accepted: 02/21/2021] [Indexed: 12/18/2022] Open
Abstract
The phosphorylation of serine 10 in histone 3 (p-S10H3) has recently been demonstrated to participate in spinal nociceptive processing. However, superficial dorsal horn (SDH) neurons involved in p-S10H3-mediated nociception have not been fully characterized. In the present work, we combined immunohistochemistry, in situ hybridization with the retrograde labeling of projection neurons to reveal the subset of dorsal horn neurons presenting an elevated level of p-S10H3 in response to noxious heat (60 °C), causing burn injury. Projection neurons only represented a small percentage (5%) of p-S10H3-positive cells, while the greater part of them belonged to excitatory SDH interneurons. The combined immunolabeling of p-S10H3 with markers of already established interneuronal classes of the SDH revealed that the largest subset of neurons with burn injury-induced p-S10H3 expression was dynorphin immunopositive in mice. Furthermore, the majority of p-S10H3-expressing dynorphinergic neurons proved to be excitatory, as they lacked Pax-2 and showed Lmx1b-immunopositivity. Thus, we showed that neurochemically heterogeneous SDH neurons exhibit the upregulation of p-S10H3 shortly after noxious heat-induced burn injury and consequential tissue damage, and that a dedicated subset of excitatory dynorphinergic neurons is likely a key player in the development of central sensitization via the p-S10H3 mediated pathway.
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The role of glutamate transporter-1 in firing activity of locus coeruleus neurons and nociception in rats. Exp Brain Res 2021; 239:1287-1294. [PMID: 33619583 DOI: 10.1007/s00221-021-06065-0] [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: 10/28/2020] [Accepted: 02/13/2021] [Indexed: 10/22/2022]
Abstract
Locus coeruleus (LC) is considered to be the main source of norepinephrine in the central nervous system (CNS) and plays important role in relieving pain in the body. Changes in the activity of synaptic excitatory amino acid transporters (EAATs) would be an applicable way to regulate synaptic transmission in the LC. In the present study, we examined the role of astrocytic glutamate transporter-1 (GLT1) in the firing activity of LC neurons and the sensation of pain in rats. Male Wistar rats were divided into three control (CNT), ceftriaxone (CFT) and dihydrokainic acid (DHK) groups. Animals were given intraperitoneal injections for nine consecutive days after which the electrophysiological and behavioral experiments were performed to determine the single-unit activity of LC neurons and pain sensation. Results of this study revealed that CFT as a well-known up-regulator of GLT1 expression decreases the latency of pain sensation in rats but inhibition of GLT1 activity by DHK showed no significant effects. Furthermore, the results obtained by single-unit recording from LC showed a significant decrease in evoked response in CFT group compared to the CNT group. Therefore, this study suggests that GLT1 might be considered as a potential therapeutic target for pain modulation in the future.
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Spinal Cord Stimulation for Pain Treatment After Spinal Cord Injury. Neurosci Bull 2018; 35:527-539. [PMID: 30560438 DOI: 10.1007/s12264-018-0320-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 08/11/2018] [Indexed: 12/30/2022] Open
Abstract
In addition to restoration of bladder, bowel, and motor functions, alleviating the accompanying debilitating pain is equally important for improving the quality of life of patients with spinal cord injury (SCI). Currently, however, the treatment of chronic pain after SCI remains a largely unmet need. Electrical spinal cord stimulation (SCS) has been used to manage a variety of chronic pain conditions that are refractory to pharmacotherapy. Yet, its efficacy, benefit profiles, and mechanisms of action in SCI pain remain elusive, due to limited research, methodological weaknesses in previous clinical studies, and a lack of mechanistic exploration of SCS for SCI pain control. We aim to review recent studies and outline the therapeutic potential of different SCS paradigms for traumatic SCI pain. We begin with an overview of its manifestations, classification, potential underlying etiology, and current challenges for its treatment. The clinical evidence for using SCS in SCI pain is then reviewed. Finally, future perspectives of pre-clinical research and clinical study of SCS for SCI pain treatment are discussed.
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Tang Y, Yin HY, Liu J, Rubini P, Illes P. P2X receptors and acupuncture analgesia. Brain Res Bull 2018; 151:144-152. [PMID: 30458249 DOI: 10.1016/j.brainresbull.2018.10.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 10/13/2018] [Accepted: 10/18/2018] [Indexed: 12/20/2022]
Abstract
Purinergic signaling has recently been suggested to constitute the cellular mechanism underlying acupuncture-induced analgesia (AA). By extending the original hypothesis on endogenous opioids being released during AA, Geoffrey Burnstock and Maiken Nedergaard supplied evidence for the involvement of purinoceptors (P2 and P1/A1 receptors) in the beneficial effects of AA. In view of certain pain states (e.g. neuropathic pain) which respond only poorly to therapy with standard analgesics, as well as with respect to the numerous unwanted effects of opioids and non-steroidal anti-inflammatory drugs, it is of great significance to search for alternative therapeutic options. Because clinical studies on AA yielded sometimes heterogeneous results, it is of eminent importance to relay on experiments carried out on laboratory animals, by evaluating the data with stringent statistical methods including comparison with a sufficient number of control groups. In this review, we summarize the state of the art situation with respect to the participation of P2 receptors in AA and try to forecast how the field is likely to move forward in the future.
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Affiliation(s)
- Yong Tang
- Medical & Nursing School, Chengdu University, 610106 Chengdu, China; Acupuncture and Tuina School, Chengdu University of Traditional Chinese Medicine, 610075 Chengdu, China.
| | - Hai-Yan Yin
- Acupuncture and Tuina School, Chengdu University of Traditional Chinese Medicine, 610075 Chengdu, China
| | - Juan Liu
- Acupuncture and Tuina School, Chengdu University of Traditional Chinese Medicine, 610075 Chengdu, China
| | - Patrizia Rubini
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universität Leipzig, 04107 Leipzig, Germany
| | - Peter Illes
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universität Leipzig, 04107 Leipzig, Germany; Acupuncture and Tuina School, Chengdu University of Traditional Chinese Medicine, 610075 Chengdu, China.
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