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Erbacher C, Britz S, Dinkel P, Klein T, Sauer M, Stigloher C, Üçeyler N. Interaction of human keratinocytes and nerve fiber terminals at the neuro-cutaneous unit. eLife 2024; 13:e77761. [PMID: 38225894 PMCID: PMC10791129 DOI: 10.7554/elife.77761] [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: 02/09/2022] [Accepted: 12/19/2023] [Indexed: 01/17/2024] Open
Abstract
Traditionally, peripheral sensory neurons are assumed as the exclusive transducers of external stimuli. Current research moves epidermal keratinocytes into focus as sensors and transmitters of nociceptive and non-nociceptive sensations, tightly interacting with intraepidermal nerve fibers at the neuro-cutaneous unit. In animal models, epidermal cells establish close contacts and ensheath sensory neurites. However, ultrastructural morphological and mechanistic data examining the human keratinocyte-nerve fiber interface are sparse. We investigated this exact interface in human skin applying super-resolution array tomography, expansion microscopy, and structured illumination microscopy. We show keratinocyte ensheathment of afferents and adjacent connexin 43 contacts in native skin and have applied a pipeline based on expansion microscopy to quantify these parameter in skin sections of healthy participants versus patients with small fiber neuropathy. We further derived a fully human co-culture system, visualizing ensheathment and connexin 43 plaques in vitro. Unraveling human intraepidermal nerve fiber ensheathment and potential interaction sites advances research at the neuro-cutaneous unit. These findings are crucial on the way to decipher the mechanisms of cutaneous nociception.
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Affiliation(s)
| | - Sebastian Britz
- Imaging Core Facility, Biocenter, University of WürzburgWürzburgGermany
| | - Philine Dinkel
- Department of Neurology, University Hospital of WürzburgWürzburgGermany
| | - Thomas Klein
- Department of Neurology, University Hospital of WürzburgWürzburgGermany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, University of WürzburgWürzburgGermany
| | | | - Nurcan Üçeyler
- Department of Neurology, University Hospital of WürzburgWürzburgGermany
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2
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Reuss S, Linsmayer D, Balmaceda-Braun J, von Rittberg J, Mitz S, Disque-Kaiser U, Usdin T, Leube RE. Synaptoporin and parathyroid hormone 2 as markers of multimodal inputs to the auditory brainstem. J Chem Neuroanat 2023; 130:102259. [PMID: 36958466 PMCID: PMC10164705 DOI: 10.1016/j.jchemneu.2023.102259] [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: 12/12/2022] [Revised: 03/05/2023] [Accepted: 03/16/2023] [Indexed: 03/25/2023]
Abstract
The distribution of the synaptic vesicle protein synaptoporin was investigated by immunofluorescence in the central auditory system of the mouse brainstem. Synaptoporin immunostaining displayed region-specific differences. High and moderate accumulations of were seen in the superficial layer of the dorsal cochlear nucleus, dorsal and external regions of the inferior colliculus, the medial and dorsal divisions of the medial geniculate body and in periolivary regions of the superior olivary complex (SOC). Low or absent labeling was observed in the more central parts of these structures such as the principal nuclei of the SOC. It was conspicuous that dense synaptoporin immunoreactivity was detected predominantly in areas, which are known to be synaptic fields of multimodal, extra-auditory inputs. Target neurons of synaptoporin-positive synapses in the SOC were then identified by double-labelling immunofluorescence microscopy. We thereby detected synaptoporin puncta perisomatically at nitrergic, glutamatergic and serotonergic neurons but none next to neurons immunoreactive for choline-acetyltransferase and calcitonin-gene related peptide. These results leave open whether functionally distinct neuronal groups are accessed in the SOC by synaptoporin-containing neurons. The last part of our study sought to find out whether synaptoporin-positive neurons originate in the medial paralemniscal nucleus (MPL), which is characterized by expression of the peptide parathyroid hormone 2 (PTH2). Anterograde neuronal tracing upon injection into the MPL in combination with synaptoporin- and PTH2-immunodetection showed that (1) the MPL projects to the periolivary SOC using PTH2 as transmitter, (2) synaptoporin-positive neurons do not originate in the MPL, and (3) the close juxtaposition of synaptoporin-staining with either the anterograde tracer or PTH2 reflect concerted action of the different inputs to the SOC.
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Affiliation(s)
- Stefan Reuss
- Department of Nuclear Medicine, University Medical Center, Johannes Gutenberg-University, Mainz, Germany.
| | - Denise Linsmayer
- Department of Anatomy and Cell Biology, University Medical Center, Johannes Gutenberg-University, Mainz, Germany
| | - Julia Balmaceda-Braun
- Department of Anatomy and Cell Biology, University Medical Center, Johannes Gutenberg-University, Mainz, Germany
| | - Julia von Rittberg
- Department of Anatomy and Cell Biology, University Medical Center, Johannes Gutenberg-University, Mainz, Germany
| | - Stephanie Mitz
- Department of Anatomy and Cell Biology, University Medical Center, Johannes Gutenberg-University, Mainz, Germany
| | - Ursula Disque-Kaiser
- Department of Anatomy and Cell Biology, University Medical Center, Johannes Gutenberg-University, Mainz, Germany
| | - Ted Usdin
- Systems Neuroscience Imaging Resource, National Institute of Mental Health, Bethesda, MD, USA
| | - Rudolf E Leube
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Aachen, Germany
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Li N, Pang Q, Zhang Y, Lin J, Li H, Li Z, Liu Y, Fang X, An Y, Bai H, Li D, Cao Z, Liu J, Yang Q, Hu S. Ginsenoside ompound K reduces neuronal damage and improves neuronal synaptic dysfunction by targeting Aβ. Front Pharmacol 2023; 14:1103012. [PMID: 36873999 PMCID: PMC9977807 DOI: 10.3389/fphar.2023.1103012] [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: 11/19/2022] [Accepted: 02/07/2023] [Indexed: 02/18/2023] Open
Abstract
Background: Alzheimer's disease (AD) is the most common neurodegenerative condition worldwide, with amyloid ß (Aβ) fibrils presenting as its main pathological feature. This study investigated whether Ginsenoside Compound K (CK) has activity against Aβ and its mechanism in reducing synaptic damage and cognitive impairment. Methods: The binding capacity of CK to Aβ42 and Nrf2/Keap1 was determined using molecular docking. Transmission electron microscopy was used to monitor CK-mediated degradation of Aβ fibrils. The effect of CK on the survival of Aβ42-damaged HT22 cells was determined using a CCK-8 assay. The therapeutic efficacy of CK in a scopoletin hydrobromide (SCOP) induced cognitive dysfunction mouse model was measured using a step-down passive avoidance test. GO enrichment analysis of mouse brain tissue was peformed using Genechip. Hydroxyl radical scavenging and reactive oxygen species assays were performed to verify the antioxidant activity of CK. The effects of CK on the expression of Aβ42, the Nrf2/Keap1 signaling pathway, and other proteins were determined by western blotting, immunofluorescence, and immunohistochemistry. Results: Molecular docking results showed that CK interacts with Lys16 and Glu3 of Aβ42. CK reduced the aggregation of Aβ42 as observed using transmission electron microscopy. CK increased the level of insulin-degrading enzyme and decreased the levels ß-secretase and γ-secretase; therefore, it can potentially inhibit the accumulation of Aβ in neuronal extracellular space in vivo. CK improved cognitive impairment and increased postsynaptic density protein 95 and synaptophysin expression levels in mice with SCOP-induced cognitive dysfunction. Further, CK inhibited the expression of cytochrome C, Caspase-3, and cleaved Caspase-3. Based on Genechip data, CK was found to regulate molecular functions such as oxygen binding, peroxidase activity, hemoglobin binding, and oxidoreductase activity, thus affecting the production of oxidative free radicals in neurons. Further, CK regulated the expression of the Nrf2/Keap1 signaling pathway through its interaction with the Nrf2/Keap1 complex. Conclusion: Our findings show that CK regulates the balance between Aβ monomers production and clearance, CK binds to Aβ monomer to inhibits the accumulation of Aβ, increases the level of Nrf2 in neuronal nuclei, reduces oxidative damage of neurons, improves synaptic function, thus ultimately protecting neurons.
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Affiliation(s)
- Na Li
- Changchun University of Chinese Medicine, Changchun, China
| | - Qihang Pang
- Changchun University of Chinese Medicine, Changchun, China
| | - Yanhong Zhang
- Changchun University of Chinese Medicine, Changchun, China
| | - Jianan Lin
- Changchun University of Chinese Medicine, Changchun, China
| | - Hui Li
- Department of General Surgery, Qian Wei Hospital of Jilin Province, Changchun, China
| | - Zhen Li
- Changchun University of Chinese Medicine, Changchun, China
| | - Yaxin Liu
- Changchun University of Chinese Medicine, Changchun, China
| | - Xingyu Fang
- Changchun University of Chinese Medicine, Changchun, China
| | - Yu An
- Changchun University of Chinese Medicine, Changchun, China
| | - Haonan Bai
- Changchun University of Chinese Medicine, Changchun, China
| | - Dianyu Li
- Changchun University of Chinese Medicine, Changchun, China
| | - Zhanhong Cao
- Changchun University of Chinese Medicine, Changchun, China
| | - Jian Liu
- Changchun University of Chinese Medicine, Changchun, China
| | - Qing Yang
- Changchun University of Chinese Medicine, Changchun, China
| | - Shaodan Hu
- Changchun University of Chinese Medicine, Changchun, China
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Zhang M, Lyu D, Wang F, Shi S, Wang M, Yang W, Huang H, Wei Z, Chen S, Xu Y, Hong W. Ketamine May Exert Rapid Antidepressant Effects Through Modulation of Neuroplasticity, Autophagy, and Ferroptosis in the Habenular Nucleus. Neuroscience 2022; 506:29-37. [PMID: 36280022 DOI: 10.1016/j.neuroscience.2022.10.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 10/14/2022] [Accepted: 10/17/2022] [Indexed: 11/06/2022]
Abstract
Major depressive disorder is a burdensome condition with few treatment options, and traditional antidepressants are characterized by slow onset. Sub-anesthetic ketamine has rapid-onset effects for the treatment of major depressive disorder (MDD), the mechanisms of which remain elusive. In this study, we explored whether neuroplasticity, autophagy, and ferroptosis in the habenular nucleus are involved in the rapid antidepressant process of ketamine. The results showed that Chronic Restraint Stress (CRS) treated rats exhibited decreased neuroplasticity, inhibition of autophagy, and enhanced ferroptosis. Depression-like symptoms were significantly improved after ketamine treatment in CRS rats, with changes in physiological parameters. Ketamine-treated CRS rats showed a significant improvement in habenular nuclear neuroplasticity. Electron microscopy observed that ketamine triggered autophagy, with increased levels of autophagy-related proteins. Ferroptosis was inhibited by ketamine by electron microscopy, with increased FTH1 and GPX4 levels and decreased Tfr1 levels. In conclusion, our findings demonstrate that ketamine may exert rapid antidepressant effects by improving neuroplasticity, activating autophagy, and inhibiting ferroptosis in the nuclear complex.
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Affiliation(s)
- Mengke Zhang
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, PR China; Shanghai Key Laboratory of Psychotic Disorders, PR China
| | - Dongbin Lyu
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, PR China; Shanghai Key Laboratory of Psychotic Disorders, PR China
| | - Fan Wang
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, PR China; Shanghai Key Laboratory of Psychotic Disorders, PR China
| | - Shuxiang Shi
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, PR China; Shanghai Key Laboratory of Psychotic Disorders, PR China
| | - Meiti Wang
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, PR China; Shanghai Key Laboratory of Psychotic Disorders, PR China
| | - Weichieh Yang
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, PR China; Shanghai Key Laboratory of Psychotic Disorders, PR China
| | - Haijing Huang
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, PR China; Shanghai Key Laboratory of Psychotic Disorders, PR China
| | - Zheyi Wei
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, PR China; Shanghai Key Laboratory of Psychotic Disorders, PR China
| | - ShenTse Chen
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, PR China; Shanghai Key Laboratory of Psychotic Disorders, PR China
| | - Yi Xu
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, PR China; Shanghai Key Laboratory of Psychotic Disorders, PR China.
| | - Wu Hong
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, PR China; Shanghai Key Laboratory of Psychotic Disorders, PR China.
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García-Mesa Y, García-Piqueras J, Cuendias P, Cobo R, Martín-Cruces J, Feito J, García-Suarez O, Biedma BM, Vega J. SYNAPTOPHYSIN IS A SELECTIVE MARKER FOR AXONS IN HUMAN CUTANEOUS END ORGAN COMPLEXES. Ann Anat 2022; 243:151955. [DOI: 10.1016/j.aanat.2022.151955] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 04/04/2022] [Accepted: 04/24/2022] [Indexed: 12/25/2022]
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6
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Intrinsic cardiac neurons of the adult pigs: chemical types, abundance, parameters and distribution within ganglionated plexus. Ann Anat 2022; 243:151935. [DOI: 10.1016/j.aanat.2022.151935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 03/04/2022] [Accepted: 03/09/2022] [Indexed: 11/18/2022]
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Needling Interventions for Sciatica: Choosing Methods Based on Neuropathic Pain Mechanisms-A Scoping Review. J Clin Med 2021; 10:jcm10102189. [PMID: 34069357 PMCID: PMC8158699 DOI: 10.3390/jcm10102189] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 05/13/2021] [Accepted: 05/17/2021] [Indexed: 02/06/2023] Open
Abstract
Sciatica is a condition often accompanied by neuropathic pain (NP). Acupuncture and dry needling are common treatments for pain, and the current literature supports acupuncture as an effective treatment for sciatica. However, it is unknown if the mechanisms of NP are considered in the delivery of needling interventions for sciatica. Our objective was to assess the efficacy and the effectiveness of needling therapies, to identify common needling practices and to investigate if NP mechanisms are considered in the treatment of sciatica. A scoping review of the literature on needling interventions for sciatica and a review of the literature on mechanisms related to NP and needling interventions were performed. Electronic literature searches were conducted on PubMed, MEDLINE, CINAHL and Cochrane Database of Systematic Reviews from inception to August, 2020 to identify relevant papers. Reference lists of included papers were also manually screened and a related-articles search through PubMed was performed on all included articles. Mapping of the results included description of included studies, summary of results, and identification of gaps in the existing literature. Ten articles were included. All studies used acupuncture for the treatment of sciatica, no studies on dry needling were identified. Current evidence supports the efficacy and effectiveness of acupuncture for sciatica, however, no studies considered underlying NP mechanisms in the acupuncture approach for sciatica and the rationale for using acupuncture was inconsistent among trials. This review reveals that neuropathic pain mechanisms are not routinely considered in needling approaches for patients with sciatica. Studies showed acupuncture to be an effective treatment for sciatic pain, however, further research is warranted to explore if needling interventions for sciatica and NP would be more effective if NP mechanisms are considered.
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8
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Zhu X, Yue L, Fan C, Liu Y, Wang Y, Zhao H. Mechanism of Cdk5-synaptophysin-SNARE pathway in acute and chronic inflammatory pain. Am J Transl Res 2021; 13:1075-1084. [PMID: 33841641 PMCID: PMC8014406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 12/10/2020] [Indexed: 06/12/2023]
Abstract
PURPOSE Currently, there is no favorable treatment plan for inflammatory pain, so exploring new analgesics is still a research hotspot in this area. Cyclin-dependent protein kinase 5 (Cdk5) is a pain-related protein kinase, but its mechanism in inflammatory pain has not been clarified. This research aimed to explore the mechanism of Cdk5-synaptophysin (Syn)-soluble N-ethylmaleimide-sensitivity factor (NSF) attachment protein receptor (SNARE) in acute and chronic inflammatory pain. METHODS Rat models of acute and chronic inflammatory pain were induced by formalin and complete Freund's adjuvant (CFA), separately, and some rats injected with normal saline through intraplantar injection were divided into a control group. Thirty minutes before modeling, rats were given Cdk5 inhibitor (Roscovitine, Ros), SNARE scavenger (botulinum toxin A, BTTA), glutamate receptor inhibitor (MK801), and dimethyl sulfoxide (DMSO) through spinal canals, and the paw withdrawal threshold (PWT) and thermal withdrawal latency (PWL) at difference time points were compared. RESULTS Compared with rats in the control group, those in the rat models of acute and chronic inflammatory pain showed lower PWT and PWL, higher Cdk5 enzyme level, tight correlation of Cdk5 with Syn, SNARE, p25 proteins, and higher levels of Cdk5, Syn and SNARE. And the above situation was dramatically reversed under intervention of Ros, BTTA and MK801. CONCLUSION Cdk5-Syn-SNARE pathway is a therapeutic target for inflammatory pain. Blocking the activation of this pathway is beneficial to exert analgesic effect.
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Affiliation(s)
- Xichun Zhu
- Department of Pain Management, Hebei General Hospital Shijiazhuang 050051, Hebei Province, China
| | - Lihui Yue
- Department of Pain Management, Hebei General Hospital Shijiazhuang 050051, Hebei Province, China
| | - Chunyan Fan
- Department of Pain Management, Hebei General Hospital Shijiazhuang 050051, Hebei Province, China
| | - Yuting Liu
- Department of Pain Management, Hebei General Hospital Shijiazhuang 050051, Hebei Province, China
| | - Yong Wang
- Department of Pain Management, Hebei General Hospital Shijiazhuang 050051, Hebei Province, China
| | - Hongwei Zhao
- Department of Pain Management, Hebei General Hospital Shijiazhuang 050051, Hebei Province, China
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9
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Wang XM, Gu P, Saligan L, Iadarola M, Wong SSC, Ti LK, Cheung CW. Dysregulation of EAAT2 and VGLUT2 Spinal Glutamate Transports via Histone Deacetylase 2 (HDAC2) Contributes to Paclitaxel-induced Painful Neuropathy. Mol Cancer Ther 2020; 19:2196-2209. [PMID: 32847971 DOI: 10.1158/1535-7163.mct-20-0006] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 04/24/2020] [Accepted: 08/05/2020] [Indexed: 11/16/2022]
Abstract
Effective treatments for chemotherapy-induced peripheral neuropathy (CIPN) remain unavailable. Given the significance of spinal cord glutamate transporters in neuronal plasticity and central sensitization, this study investigated the role of excitatory amino acid transporter 2 (EAAT2) and vesicular-glutamate transporter 2 (VGLUT2) in the development of paclitaxel-induced painful neuropathy. Paclitaxel (2 mg/kg, i.p., cumulative dose 8 mg/kg) induced long-lasting mechanical allodynia (>28 days) with increased glutamate concentration and decreased EAAT2 expression with no changes in GABA/glycine or VGAT (vesicular GABA transporter) in rat spinal dorsal horn. VGLUT2 expression was upregulated and coexpressed with enhanced synaptophysin, characterizing nociceptive afferent sprouting and new synapse formation of glutamatergic neurons in the spinal cord dorsal horn. HDAC2 and transcription factor YY1 were also upregulated, and their interaction and colocalization were confirmed following paclitaxel treatment using co-immunoprecipitation. Inhibition or knockdown of HDAC2 expression by valproic acid, BRD6688, or HDAC2 siRNA not only attenuated paclitaxel-induced mechanical allodynia but also suppressed HDAC2 upregulation, glutamate accumulation, and the corresponding changes in EAAT2/VGLUT/synaptophysin expression and HDAC2/YY1 interaction. These findings indicate that loss of the balance between glutamate release and reuptake due to dysregulation EAAT2/VGLUT2/synaptophysin cascade in the spinal dorsal horn plays an important role in the development of paclitaxel-induced neuropathic pain. HDAC2/YY1 interaction as a complex appears essential in regulating this pathway, which can potentially be a therapeutic target to relieve CIPN by reversing central sensitization of spinal nociceptive neurons.
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Affiliation(s)
- Xiao-Min Wang
- Laboratory and Clinical Research Institute for Pain, Department of Anaesthesiology, The University of Hong Kong, Hong Kong, SAR, China.
| | - Pan Gu
- Laboratory and Clinical Research Institute for Pain, Department of Anaesthesiology, The University of Hong Kong, Hong Kong, SAR, China
| | - Leorey Saligan
- National Institute of Nursing Research, Division of Intramural Research, NIH, Bethesda, Maryland
| | - Michael Iadarola
- Anesthesiology Research Laboratories, Department of Perioperative Medicine, Clinical Center, NIH, Bethesda, Maryland
| | - Stanley Sau Ching Wong
- Laboratory and Clinical Research Institute for Pain, Department of Anaesthesiology, The University of Hong Kong, Hong Kong, SAR, China.,Department of Anaesthesiology, The University of Hong Kong, Hong Kong, SAR, China
| | - Lian Kah Ti
- Department of Anaesthesia, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Chi Wai Cheung
- Laboratory and Clinical Research Institute for Pain, Department of Anaesthesiology, The University of Hong Kong, Hong Kong, SAR, China. .,Department of Anaesthesiology, The University of Hong Kong, Hong Kong, SAR, China
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10
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Lee HJ, White JM, Chung J, Malone P, DeWeerth SP, Tansey KE. Differential cardiovascular responses to cutaneous afferent subtypes in a nociceptive intersegmental spinal reflex. Sci Rep 2019; 9:19049. [PMID: 31836817 PMCID: PMC6911054 DOI: 10.1038/s41598-019-54072-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 11/08/2019] [Indexed: 11/24/2022] Open
Abstract
Electrical stimulation to segmental dorsal cutaneous nerves (DCNs) activates a nociceptive sensorimotor reflex and the same afferent stimulation also evokes blood pressure (BP) and heart rate (HR) responses in rats. To investigate the relationship between those cardiovascular responses and the activation of nociceptive afferents, we analyzed BP and HR responses to electrical stimulations at each DCN from T6 to L1 at 0.5 mA to activate A-fiber alone or 5 mA to activate both A- and C-fibers at different frequencies. Evoked cardiovascular responses showed a decrease and then an increase in BP and an increase and then a plateau in HR. Segmentally, both cardiovascular responses tended to be larger when evoked from the more rostral DCNs. Stimulation frequency had a larger effect on cardiovascular responses than the rostrocaudal level of the DCN input. Stimulation strength showed a large effect on BP changes dependent on C-fibers whereas HR changes were dependent on A-fibers. Additional A-fiber activation by stimulating up to 4 adjacent DCNs concurrently, but only at 0.5 mA, affected HR but not BP. These data support that cutaneous nociceptive afferent subtypes preferentially contribute to different cardiovascular responses, A-fibers to HR and C-fibers to BP, with temporal (stimulation frequency) and spatial (rostrocaudal level) dynamics.
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Affiliation(s)
- Hyun Joon Lee
- Departments of Neurology and Physiology, Emory University, Atlanta, GA, USA.,Departments of Neurology, University of Mississippi Medical Center, Jackson, MS, USA.,Departments of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS, USA.,G.V. (Sonny) Montgomery VA Medical Center, Jackson, MS, USA
| | - Jason M White
- Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, GA, USA
| | - Jumi Chung
- Departments of Neurology and Physiology, Emory University, Atlanta, GA, USA.,Departments of Neurology, University of Mississippi Medical Center, Jackson, MS, USA.,G.V. (Sonny) Montgomery VA Medical Center, Jackson, MS, USA
| | - Patrick Malone
- Departments of Neurology and Physiology, Emory University, Atlanta, GA, USA
| | - Stephen P DeWeerth
- Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, GA, USA.,School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Keith E Tansey
- Departments of Neurology and Physiology, Emory University, Atlanta, GA, USA. .,Spinal Cord Injury Clinic, Atlanta VA Medical Center, Atlanta, GA, USA. .,Departments of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS, USA. .,Departments of Neurosurgery, University of Mississippi Medical Center, Jackson, MS, USA. .,G.V. (Sonny) Montgomery VA Medical Center, Jackson, MS, USA. .,NeuroRobotics Lab, Methodist Rehabilitation Center, Jackson, MS, USA.
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11
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Central Plasticity of Cutaneous Afferents Is Associated with Nociceptive Hyperreflexia after Spinal Cord Injury in Rats. Neural Plast 2019; 2019:6147878. [PMID: 31827498 PMCID: PMC6885787 DOI: 10.1155/2019/6147878] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 05/30/2019] [Accepted: 09/05/2019] [Indexed: 11/18/2022] Open
Abstract
Electrical stimulations of dorsal cutaneous nerves (DCNs) at each lumbothoracic spinal level produce the bilateral cutaneus trunci muscle (CTM) reflex responses which consist of two temporal components: an early and late responses purportedly mediated by Aδ and C fibers, respectively. We have previously reported central projections of DCN A and C fibers and demonstrated that different projection patterns of those afferent types contributed to the somatotopic organization of CTM reflex responses. Unilateral hemisection spinal cord injury (SCI) was made at T10 spinal segments to investigate the plasticity of early and late CTM responses 6 weeks after injury. Both early and late responses were drastically increased in response to both ipsi- and contralateral DCN stimulations both above (T6 and T8) and below (T12 and L1) the levels of injury demonstrating that nociceptive hyperreflexia developed at 6 weeks following hemisection SCI. We also found that DCN A and C fibers centrally sprouted, expanded their projection areas, and increased synaptic terminations in both T7 and T13, which correlated with the size of hemisection injury. These data demonstrate that central sprouting of cutaneous afferents away from the site of injury is closely associated with enhanced responses of intraspinal signal processing potentially contributing to nociceptive hyperreflexia following SCI.
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