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Chen H, Jiang L, Zhang D, Chen J, Luo X, Xie Y, Han T, Wang L, Zhang Z, Zhou X, Yan H. Exploring the Correlation Between the Regulation of Macrophages by Regulatory T Cells and Peripheral Neuropathic Pain. Front Neurosci 2022; 16:813751. [PMID: 35237123 PMCID: PMC8882923 DOI: 10.3389/fnins.2022.813751] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 01/25/2022] [Indexed: 11/13/2022] Open
Abstract
ObjectiveIntractable pain after peripheral nerve injury has become a major concern in the field of pain. Current evidence shows that routine medications or surgical treatment is associated with inconsistent results and different curative effects. Stable and effective treatment methods in clinical practice are also lacking. To date, there is no consensus on the pathophysiological mechanisms of pain. The present study investigates the potential regulatory role of regulatory T cells in the differentiation of macrophages on dorsal root ganglion (DRG) and explores the mechanism of nociceptive signals in the signal transfer station. The findings are expected to guide the prevention of various types of peripheral neuropathic pain.MethodsThirty-six male Sprague Dawley (SD) rats and 18 male Nude rats, of equal weight (250–300g), were used in this study. The rats were divided into 3 groups: SD rat sciatic nerve transection group (SNT group, n = 18), SD rat nerve transection experimental group (SNT/RAPA group, n = 18) and Nude rat nerve transection experimental group (SNT/NUDE group, n = 18). The behavior related to neuropathic pain of animals were comprehensively evaluated in all groups. Furthermore, we analyzed the degree of neuroma development, histology, gene, and protein expression, and compared their correlation with the ultrastructural changes of M1/M2 type differentiation of macrophages in DRG.ResultsSciatic nerve transection (SNT), induced the aggregation of several types of macrophages in lumbar DRG of SD rats leading to a higher ratio of M1/M2. Following the inhibition of the M1 type polarization of macrophages, axon outgrowth increased significantly. A significantly lower average autotomy score was reported in the SNT/NUDE group (*p < 0.05) and the SNT/RAPA group (@p < 0.05) as compared to that of the SNT group. The SNT/NUDE group showed no noticeable neuroma formation 30 days after the nerve transection. However, bulbous neuromas were observed in the nerve stumps of both the SNT control and SNT/RAPA groups. Immunofluorescence staining revealed a significant decrease in the proportion of M1/M2 macrophages in lumbar DRG of the SNT/NUDE group (**p < 0.001) and the SNT/RAPA group (@p < 0.05) compared to the SNT group. The expression of pain-related proteins was also decreased (@p < 0.05, *p < 0.05,**p < 0.001). Also, the expression of alpha-smooth muscle actin (α-SMA), neurofilament 200 (NF-200), and nerve growth factor low-affinity receptor p75 were significantly down-regulated in the nerve tissue (@p < 0.05, @@p < 0.001, **p < 0.001).ConclusionM1/M2 type differentiation of macrophages on DRG plays a significant role in the formation of traumatic painful neuroma after neurotomy. In combination with our previous study, the results of this study suggest that regulatory T cells reduce the ratio of M1/M2 macrophages and alleviate the pain of neuroma by regulating the polarization direction of macrophages on neuroma. These findings provide key insights into developing new strategies to manage painful neuroma.
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Affiliation(s)
- Hongyu Chen
- Division of Hand Surgery, Department of Orthopedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- Key Laboratory of Orthopedics of Zhejiang Province, Wenzhou, China
- The Second School of Medicine, Wenzhou Medical University, Wenzhou, China
| | - Liangfu Jiang
- Division of Hand Surgery, Department of Orthopedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- Key Laboratory of Orthopedics of Zhejiang Province, Wenzhou, China
| | - Dupiao Zhang
- Division of Hand Surgery, Department of Orthopedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- Key Laboratory of Orthopedics of Zhejiang Province, Wenzhou, China
- The Second School of Medicine, Wenzhou Medical University, Wenzhou, China
| | - Jianpeng Chen
- Division of Hand Surgery, Department of Orthopedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- Key Laboratory of Orthopedics of Zhejiang Province, Wenzhou, China
- The Second School of Medicine, Wenzhou Medical University, Wenzhou, China
| | - Xiaobin Luo
- Division of Hand Surgery, Department of Orthopedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- Key Laboratory of Orthopedics of Zhejiang Province, Wenzhou, China
| | - Yutong Xie
- Key Laboratory of Orthopedics of Zhejiang Province, Wenzhou, China
- The Second School of Medicine, Wenzhou Medical University, Wenzhou, China
| | - Tao Han
- Division of Hand Surgery, Department of Orthopedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- Key Laboratory of Orthopedics of Zhejiang Province, Wenzhou, China
- The Second School of Medicine, Wenzhou Medical University, Wenzhou, China
| | - Liang Wang
- Division of Hand Surgery, Department of Orthopedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- Key Laboratory of Orthopedics of Zhejiang Province, Wenzhou, China
- The Second School of Medicine, Wenzhou Medical University, Wenzhou, China
| | - Zhe Zhang
- Division of Hand Surgery, Department of Orthopedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- Key Laboratory of Orthopedics of Zhejiang Province, Wenzhou, China
- The Second School of Medicine, Wenzhou Medical University, Wenzhou, China
| | - Xijie Zhou
- Division of Hand Surgery, Department of Orthopedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- Key Laboratory of Orthopedics of Zhejiang Province, Wenzhou, China
- *Correspondence: Xijie Zhou,
| | - Hede Yan
- Division of Hand Surgery, Department of Orthopedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- Key Laboratory of Orthopedics of Zhejiang Province, Wenzhou, China
- Hede Yan,
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The Role of Hypothalamic Neuropeptides in Neurogenesis and Neuritogenesis. Neural Plast 2016; 2016:3276383. [PMID: 26881105 PMCID: PMC4737468 DOI: 10.1155/2016/3276383] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 11/18/2015] [Accepted: 11/22/2015] [Indexed: 01/23/2023] Open
Abstract
The hypothalamus is a source of neural progenitor cells which give rise to different populations of specialized and differentiated cells during brain development. Newly formed neurons in the hypothalamus can synthesize and release various neuropeptides. Although term neuropeptide recently undergoes redefinition, small-size hypothalamic neuropeptides remain major signaling molecules mediating short- and long-term effects on brain development. They represent important factors in neurite growth and formation of neural circuits. There is evidence suggesting that the newly generated hypothalamic neurons may be involved in regulation of metabolism, energy balance, body weight, and social behavior as well. Here we review recent data on the role of hypothalamic neuropeptides in adult neurogenesis and neuritogenesis with special emphasis on the development of food intake and social behavior related brain circuits.
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Magnussen C, Hung SP, Ribeiro-da-Silva A. Novel expression pattern of neuropeptide Y immunoreactivity in the peripheral nervous system in a rat model of neuropathic pain. Mol Pain 2015; 11:31. [PMID: 26012590 PMCID: PMC4449610 DOI: 10.1186/s12990-015-0029-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 05/20/2015] [Indexed: 12/26/2022] Open
Abstract
Background Neuropeptide Y (NPY) has been implicated in the modulation of pain. Under normal conditions, NPY is found in interneurons in the dorsal horn of the spinal cord and in sympathetic postganglionic neurons but is absent from the cell bodies of sensory neurons. Following peripheral nerve injury NPY is dramatically upregulated in the sensory ganglia. How NPY expression is altered in the peripheral nervous system, distal to a site of nerve lesion, remains unknown. To address this question, NPY expression was investigated using immunohistochemistry at the level of the trigeminal ganglion, the mental nerve and in the skin of the lower lip in relation to markers of sensory and sympathetic fibers in a rat model of trigeminal neuropathic pain. Results At 2 and 6 weeks after chronic constriction injury (CCI) of the mental nerve, de novo expression of NPY was seen in the trigeminal ganglia, in axons in the mental nerve, and in fibers in the upper dermis of the skin. In lesioned animals, NPY immunoreactivity was expressed primarily by large diameter mental nerve sensory neurons retrogradely labelled with Fluorogold. Many axons transported this de novo NPY to the periphery as NPY-immunoreactive (IR) fibers were seen in the mental nerve both proximal and distal to the CCI. Some of these NPY-IR axons co-expressed Neurofilament 200 (NF200), a marker for myelinated sensory fibers, and occasionally colocalization was seen in their terminals in the skin. Peptidergic and non-peptidergic C fibers expressing calcitonin gene-related peptide (CGRP) or binding isolectin B4 (IB4), respectively, never expressed NPY. CCI caused a significant de novo sprouting of sympathetic fibers into the upper dermis of the skin, and most, but not all of these fibers, expressed NPY. Conclusions This is the first study to provide a comprehensive description of changes in NPY expression in the periphery after nerve injury. Novel expression of NPY in the skin comes mostly from sprouted sympathetic fibers. This information is fundamental in order to understand where endogenous NPY is expressed, and how it might be acting to modulate pain in the periphery.
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Affiliation(s)
- Claire Magnussen
- Department of Pharmacology and Therapeutics, McGill University, McIntyre Medical Building, 3655 Promenade Sir William Osler, Room 1215, Montreal, Quebec, H3G 1Y6, Canada. .,Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec, H3A 0G1, Canada.
| | - Shih-Ping Hung
- Department of Pharmacology and Therapeutics, McGill University, McIntyre Medical Building, 3655 Promenade Sir William Osler, Room 1215, Montreal, Quebec, H3G 1Y6, Canada.
| | - Alfredo Ribeiro-da-Silva
- Department of Pharmacology and Therapeutics, McGill University, McIntyre Medical Building, 3655 Promenade Sir William Osler, Room 1215, Montreal, Quebec, H3G 1Y6, Canada. .,Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec, H3A 0G1, Canada. .,Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, H3A 0C7, Canada.
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Yan H, Zhang F, Kolkin J, Wang C, Xia Z, Fan C. Mechanisms of nerve capping technique in prevention of painful neuroma formation. PLoS One 2014; 9:e93973. [PMID: 24705579 PMCID: PMC3976365 DOI: 10.1371/journal.pone.0093973] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Accepted: 03/12/2014] [Indexed: 01/15/2023] Open
Abstract
Nerve capping techniques have been introduced as a promising treatment modality for the treatment of painful neuroma with varied outcomes; however, its exact mechanism is still unknown. RhoA is one of the members of the RAS superfamily of GTPases that operate as molecular switches and plays an important role in peripheral nerve regeneration. Our aim was to investigate the structural and morphologic mechanisms by which the nerve capping technique prevents the formation of painful neuromas after neuroectomy. We also hoped to provide a theoretical basis for this treatment approach. An aligned nanofiber conduit was used for the capping procedure and the sciatic nerve of Sprague-Dawley rats was selected as the animal model. Behavioral analysis, extent of neuroma formation, histological assessment, expressions of pain markers of substance P and c-fos, molecular biological changes as well as ultrastructural features were investigated and compared with the findings in a no-capping control group. The formation of traumatic neuromas was significantly inhibited in the capping group with relatively “normal” structural and morphological features and no occurrence of autotomy and significantly lower expression of pain markers compared to the no-capping group. The gene expression of RhoA was consistently in a higher level in the capping group within 8 weeks after surgery. This study shows that capping technique will alter the regeneration state of transected nerves and reduce painful neuroma formation, indicating a promising approach for the treatment of painful neuroma. The initiation of the “regenerative brake” induced by structural as well as morphological improvements in the severed nerve is theorized to be most likely a key mechanism for the capping technique in the prevention of painful neuroma formation.
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Affiliation(s)
- Hede Yan
- Department of Orthopedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
- Department of Orthopaedics (Division of Plastic and Hand Surgery), The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Feng Zhang
- Division of Plastic Surgery, University of Mississippi Medical Center, Jackson, Mississippi, United States of America
| | - Jon Kolkin
- Department of Plastic and Hand Surgery, Duke Raleigh Hospital, Raleigh, North Carolina, United States of America
| | - Chunyang Wang
- Department of Orthopedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Zhen Xia
- Department of Orthopedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Cunyi Fan
- Department of Orthopedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
- * E-mail:
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Webber CA, Salame J, Luu GLS, Acharjee S, Ruangkittisakul A, Martinez JA, Jalali H, Watts R, Ballanyi K, Guo GF, Zochodne DW, Power C. Nerve growth factor acts through the TrkA receptor to protect sensory neurons from the damaging effects of the HIV-1 viral protein, Vpr. Neuroscience 2013; 252:512-25. [PMID: 23912036 DOI: 10.1016/j.neuroscience.2013.07.046] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 06/30/2013] [Accepted: 07/22/2013] [Indexed: 01/19/2023]
Abstract
Distal sensory polyneuropathy (DSP) with associated neuropathic pain is the most common neurological disorder affecting patients with human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS). Viral protein R (Vpr) is a neurotoxic protein encoded by HIV-1 and secreted by infected macrophages. Vpr reduces neuronal viability, increases cytosolic calcium and membrane excitability of cultured dorsal root ganglion (DRG) sensory neurons, and is associated with mechanical allodynia in vivo. A clinical trial with HIV/AIDS patients demonstrated that nerve growth factor (NGF) reduced the severity of DSP-associated neuropathic pain, a problem linked to damage to small diameter, potentially NGF-responsive fibers. Herein, the actions of NGF were investigated in our Vpr model of DSP and we demonstrated that NGF significantly protected sensory neurons from the effects of Vpr. Footpads of immunodeficient Vpr transgenic (vpr/RAG1(-/-)) mice displayed allodynia (p<0.05), diminished epidermalinnervation (p<0.01) and reduced NGF mRNA expression (p<0.001) compared to immunodeficient (wildtype/RAG1(-/-)) littermate control mice. Compartmented cultures confirmed recombinant Vpr exposure to the DRG neuronal perikarya decreased distal neurite extension (p<0.01), whereas NGF exposure at these distal axons protected the DRG neurons from the Vpr-induced effect on their cell bodies. NGF prevented Vpr-induced attenuation of the phosphorylated glycogen synthase-3 axon extension pathway and tropomyosin-related kinase A (TrkA) receptor expression in DRG neurons (p<0.05) and it directly counteracted the cytosolic calcium burst caused by Vpr exposure to DRG neurons (p<0.01). TrkA receptor agonist indicated that NGFacted through the TrkA receptor to block the Vpr-mediated decrease in axon outgrowth in neonatal and adult rat and fetal human DRG neurons (p<0.05). Similarly, inhibiting the lower affinity NGF receptor, p75, blocked Vpr's effect on DRG neurons. Overall, NGF/TrkA signaling or p75 receptor inhibition protects somatic sensory neurons exposed to Vpr, thus laying the groundwork for potential therapeutic options for HIV/AIDS patients suffering from DSP.
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Affiliation(s)
- C A Webber
- Division of Anatomy, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
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Abstract
This review provides an overview of selected aspects of peripheral nerve regeneration and potential avenues to explore therapeutically. The overall coordinated and orchestrated pattern of recovery from peripheral nerve injury has a beauty of execution and progress that rivals all other forms of neurobiology. It involves changes at the level of the perikaryon, coordination with important peripheral glial partners, the Schwann cells, a controlled inflammatory response, and growth that overcomes surprising intrinsic roadblocks. Both regenerative axon growth and collateral sprouting encompass fascinating aspects of this story. Better understanding of peripheral nerve regeneration may also lead to enhanced central nervous system recovery.
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Affiliation(s)
- Douglas W Zochodne
- Department of Clinical Neurosciences and the Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
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7
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RETRACTED: Local erythropoietin signaling enhances regeneration in peripheral axons. Neuroscience 2008; 154:767-83. [DOI: 10.1016/j.neuroscience.2008.03.052] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Revised: 03/18/2008] [Accepted: 03/19/2008] [Indexed: 12/12/2022]
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Tsai YJ, Lin CT, Lue JH. Characterization of the Induced Neuropeptide Y–Like Immunoreactivity in Primary Sensory Neurons following Complete Median Nerve Transection. J Neurotrauma 2007; 24:1878-88. [DOI: 10.1089/neu.2007.3488] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Yi-Ju Tsai
- School of Medicine, College of Medicine, Fu Jen Catholic University, Taipei, Taiwan
| | - Chi-Te Lin
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - June-Horng Lue
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
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Weragoda RMS, Walters ET. Serotonin Induces Memory-Like, Rapamycin-Sensitive Hyperexcitability in Sensory Axons ofAplysiaThat Contributes to Injury Responses. J Neurophysiol 2007; 98:1231-9. [PMID: 17634332 DOI: 10.1152/jn.01189.2006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The induction of long-term facilitation (LTF) of synapses of Aplysia sensory neurons (SNs) by serotonin (5-HT) has provided an important mechanistic model of memory, but little is known about other long-term effects of 5-HT on sensory properties. Here we show that crushing peripheral nerves results in long-term hyperexcitability (LTH) of the axons of these nociceptive SNs that requires 5-HT activity in the injured nerve. Serotonin application to a nerve segment induces local axonal (but not somal) LTH that is inhibited by 5-HT–receptor antagonists. Blockade of crush-induced axonal LTH by an antagonist, methiothepin, provides evidence for mediation of this injury response by 5-HT. This is the first demonstration in any axon of neuromodulator-induced LTH, a phenomenon potentially important for long-lasting pain. Methiothepin does not reduce axonal LTH induced by local depolarization, so 5-HT is not required for all forms of axonal LTH. Serotonin-induced axonal LTH is expressed as reduced spike threshold and increased repetitive firing, whereas depolarization-induced LTH involves only reduced threshold. Like crush- and depolarization-induced LTH, 5-HT–induced LTH is blocked by inhibiting protein synthesis. Blockade by rapamycin, which also blocks synaptic LTF, is interesting because the eukaryotic protein kinase that is the target of rapamycin (TOR) has a conserved role in promoting growth by stimulating translation of proteins required for translation. Rapamycin sensitivity suggests that localized increases in translation of proteins that promote axonal conduction and excitability at sites of nerve injury may be regulated by the same signals that increase translation of proteins that promote neuronal growth.
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Affiliation(s)
- Ramal M S Weragoda
- Department of Integrative Biology and Pharmacology, University of Texas-Houston Medical School, 6431 Fannin Blvd. MSB 4.116, Houston, TX 77030, USA
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Abstract
The disabling human syndrome of "neuropathic pain" is an intractable complication of peripheral nerve injury or degeneration. A complex interaction between injured peripheral axons, sensory neurons and central nervous system signaling is thought to account for it. In this brief review, we present evidence that the free radical signaling molecule, nitric oxide (NO) may act at several levels of the nervous system during the development of experimental neuropathic pain. For example, NO may directly influence injured axons in the periphery, may indirectly influence pain by its role in the process of Wallerian degeneration, and may signal in the dorsal horn of the spinal cord. While it is premature to argue for therapeutic approaches that alter NO actions, it may be an important player in the cascade of events that generate neuropathic pain.
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Affiliation(s)
- Dan Levy
- Department of Anesthesia and Critical Care, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA.
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Toth C, Brussee V, Martinez JA, McDonald D, Cunningham FA, Zochodne DW. Rescue and regeneration of injured peripheral nerve axons by intrathecal insulin. Neuroscience 2006; 139:429-49. [PMID: 16529870 DOI: 10.1016/j.neuroscience.2005.11.065] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2005] [Revised: 11/11/2005] [Accepted: 11/20/2005] [Indexed: 01/01/2023]
Abstract
Insulin peptide, acting through tyrosine kinase receptor pathways, contributes to nerve development or repair. In this work, we examined the direction, impact and repertoire of insulin signaling in vivo during peripheral nerve regeneration in rats. First, we demonstrated that insulin receptor is expressed on lumbar dorsal root ganglia neuronal perikarya using immunohistochemistry. Immunoblots and polymerase chain reactions confirmed the presence of both alpha and beta insulin receptor subunits in dorsal root ganglia. In vivo and in vitro assessment of dorsal root ganglion neurons showed preferential localization of insulin receptor to perikaryal sites. In vivo, intrathecal delivery of fluorescein isothiocyanate-labeled insulin identified localization around dorsal root ganglia neurons. The direction and impact of potential insulin signaling was evaluated by concurrently delivering insulin or carrier over a 2 week period using mini-osmotic pumps, either intrathecally, near nerve, or with both deliveries, following a selective sural nerve crush injury. Only intrathecal insulin increased the number and maturity of regenerating sensory sural nerve axons distal to the crush site. As well, only intrathecal insulin rescued retrograde loss of sural axons after crush. In a separate experiment, insulin also rescued retrograde loss and atrophy of deep peroneal, largely motor, axons post-injury. Intrathecal insulin increased the expression of calcitonin-gene-related peptide in regenerating sprouts, increased the number of visualized regenerating fiber clusters, and reduced downregulation of calcitonin-gene-related peptide in dorsal root ganglia neurons. Insulin delivered intrathecally does not appear to influence expression of insulin-like growth factor-1 at dorsal root ganglion neurons or near peripheral nerve injury, but was associated with upregulation of insulin receptor alpha subunit in dorsal root ganglia. Intrathecal insulin delivery was associated with greater recovery of thermal sensation and longer distances to stimulus response with the pinch test following sural nerve crush. Insulin signaling at neuron perikarya can drive distal sensory axon regrowth, rescue retrograde alterations of axons and alter axon peptide expression. Moreover, such actions are associated with upregulation of its own receptor.
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Affiliation(s)
- C Toth
- Department of Clinical Neurosciences and the Hotchkiss Brain Institute, University of Calgary, Room 168, 3330 Hospital Drive, NW, Calgary, Alberta, Canada T2N 4N1
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Li XQ, Verge VMK, Johnston JM, Zochodne DW. CGRP Peptide and Regenerating Sensory Axons. J Neuropathol Exp Neurol 2004; 63:1092-103. [PMID: 15535136 DOI: 10.1093/jnen/63.10.1092] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
CGRP peptide, a widely expressed constituent of sensory neurons, plays important roles in nerve function and repair when axons are severed. CGRP synthesis declines, yet peptide nonetheless accumulates in severed axon endbulbs. In this work we explore an apparent selective and ongoing expression of CGRP peptide in regenerative sensory axon sprouts. Following sural nerve crush in rats out to 14 days, regenerating and branching sensory axons had intense and selective expression of CGRP, not associated with endbulbs. Parent L4 and L5 perikarya and axons in the sural nerve proximal to crush, however, did not exhibit such heightened CGRP presence. Instead, back labeling of regenerating axons with fluorogold or diamidino yellow labeled perikarya with reduced CGRP expression. Similarly, ATF-3, a robust marker of axotomized neurons, was associated with reduced, rather than elevated expression of alphaCGRP mRNA. Unexpectedly, however, we identified an enlarged secondary population of intact uninjured neurons, frequently smaller and projecting to the dorsal horn with new and heightened intense CGRP expression but not ATF-3- or tracer-labeled. Distal regenerating sensory axons selectively express CGRP peptide despite reduced perikaryal content, a phenomenon not explained by simple accumulation. Having an injured neighbor neuron, however, may also paradoxically alter how CGRP is expressed in intact neurons.
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Affiliation(s)
- Xia-Qing Li
- Department of Clinical Neurosciences, Neuroscience Research Group, University of Calgary, Alberta, Canada
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Murashov AK, Islamov RR, McMurray RJ, Pak ES, Weidner DA. Estrogen increases retrograde labeling of motoneurons: evidence of a nongenomic mechanism. Am J Physiol Cell Physiol 2004; 287:C320-6. [PMID: 15044155 DOI: 10.1152/ajpcell.00542.2003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Estrogen has a variety of neurotrophic effects mediated via different signaling cascades, including ERK and phosphatidylinositol 3-kinase (PI3K) pathways. In this study, we investigated effects of estrogen and inhibitors for ERK and PI3K applied directly onto the cut sciatic nerve on retrograde labeling of lumbar motoneurons. A mix of retrograde tracer (Fluorogold) and 17beta-estradiol, in combination with an antagonist for estrogen receptors ICI 182,780, an inhibitor of ERK1/2 pathway (U0126), an inhibitor of PI3K (LY-294002), or a protein synthesis inhibitor (cycloheximide), was applied to the proximal stump of the transected sciatic nerve for 24 h. Coapplication of Fluorogold with 17beta-estradiol produced a significant increase in the number of retrograde-labeled lumbar motoneurons, compared with Fluorogold alone. Estrogen potentiation of retrograde labeling was inhibited by application of ICI 182,780, U0126, LY-294002, and cycloheximide. Immunohistochemical analysis of the sciatic nerve, 24 h following crush injury, revealed accumulation of phospho-ERK in regenerating nerve fibers. The data suggest a role for estrogen, ERK, PI3K, and protein synthesis in the uptake and retrograde transport of Fluorogold. We propose that estrogen action in peripheral nerve fibers is mediated via the ERK and PI3K signaling pathways and is reliant on local protein synthesis.
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Affiliation(s)
- Alexander K Murashov
- Department of Physiology, Brody School of Medicine, East Carolina University, Brody Bldg. #6N-98, 600 Moye Blvd., Greenville, NC 27858, USA.
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Bird EV, Boissonade FM, Robinson PP. Neuropeptide expression following ligation of the ferret lingual nerve. Arch Oral Biol 2003; 48:541-6. [PMID: 12798158 DOI: 10.1016/s0003-9969(03)00101-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Previous studies on the ferret inferior alveolar nerve found a close association between the spontaneous neural activity generated at a site of nerve injury, and the accumulation of neuropeptides in the injured axons. More recent electrophysiological studies on the lingual nerve revealed high levels of spontaneous activity 3 days after injury, a decline at 3 weeks and a late rise at 3 months. In the present study we have used immunocytochemical techniques to see whether this time course of spontaneous activity is again paralleled by an accumulation of neuropeptides. In 20 anaesthetised adult ferrets the left lingual nerve was ligated and sectioned distally, and the animals left to recover for 3 days, 3 weeks or 3 months. The tissue was processed using indirect immunofluorescence and image analysis was used to quantify levels of the neuropeptides; calcitonin gene-related peptide (CGRP), substance P (SP), vasoactive intestinal polypeptide (VIP), galanin (GAL), enkephalin (ENK) and neuropeptide Y (NPY). Immunoreactivity to all of the neuropeptides was present proximal to the ligature 3 days after injury, and these high levels of expression had decreased considerably by 3 weeks. By 3 months ENK and NPY expression had almost disappeared proximal to the ligature, but levels of CGRP, SP, VIP and GAL had increased slightly. This was also accompanied by an accumulation of all of the neuropeptides, except NPY, in the portion of nerve immediately distal to the ligature. This late accumulation of certain neuropeptides coincides with the increase in spontaneous activity seen in our previous electrophysiological studies and supports the suggestion that neuropeptides may play a role in the aetiology of sensory disorders after nerve injury.
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Affiliation(s)
- E V Bird
- Department of Oral and Maxillofacial Surgery, School of Clinical Dentistry, University of Sheffield, Claremont Crescent, Sheffield S10 2TA, UK.
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Truong W, Cheng C, Xu QG, Li XQ, Zochodne DW. Mu opioid receptors and analgesia at the site of a peripheral nerve injury. Ann Neurol 2003; 53:366-75. [PMID: 12601704 DOI: 10.1002/ana.10465] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Opioid ligands may exert antinociception through receptors expressed on peripheral afferent axons. Whether local opioid receptors might attenuate neuropathic pain is uncertain. In this work, we examined the function and expression of local mu opioid receptors (MORs) associated with the chronic constriction injury (CCI) model of sciatic neuropathic pain in rats. Low-dose morphine or its carrier were percutaneously superfused over the CCI site with the injector blinded to the identity of the injectate. Morphine, but not its carrier, and not equimolar systemic doses of morphine reversed thermal hyperalgesia in a dose-related, naloxone-sensitive fashion. Moreover, analgesia was conferred at both 48 hours and 14 days after CCI, times associated with very different stages of nerve repair. Equimolar local DAGO ([D-Ala2, N-Me-Phe4, Gly5-(ol)] enkephalin), a selective MOR ligand, provided similar analgesia. Local morphine also attenuated mechanical allodynia. MOR protein was expressed in axonal endbulbs of Cajal just proximal to the injury site, in aberrantly regenerating small axons in the epineurial sheath around the CCI site and in residual small axons distal to the CCI lesion. Sensory neurons ipsilateral to CCI had an increase in the proportion of neurons expressing MOR. We suggest that local MOR expressed in axons may be exploited to modulate some forms of neuropathic pain.
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Affiliation(s)
- Wayne Truong
- Department of Clinical Neurosciences and the Neuroscience Research Group, University of Calgary, Calgary, Alberta, Canada
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Zochodne DW. Nerve and ganglion blood flow in diabetes: an appraisal. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2003; 50:161-202. [PMID: 12198810 DOI: 10.1016/s0074-7742(02)50077-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Vasa nervorum, the vascular supply to peripheral nerve trunks, and their associated cell bodies in ganglia have unique anatomical and physiological characteristics. Several different experimental approaches toward understanding the changes in vase nervorum following injury and disease have been used. Quantative techniques most widely employed have been microelectrode hydrogen clearance palarography and [14C]iodoantipyrine autoradiographic distribution, whereas estimates of red blood cell flux using a fiber-optic laser Doppler probe offer real time data at different sites along the nerve trunk. There are important caveats about the use of these techniques, their advantages, and their limitations. Reports of nerve blood flow require careful documentation of physiological variables, including mean arterial pressure and nerve temperature during the recordings. Several ischemic models of the peripheral nerve trunk have addressed the ischemic threshold below which axonal degeneration ensues (< 5ml/100 g/min). Following injury, rises in local blood flow reflect acitons of vasoactive peptides, nitric oxide, and the development of angiogenesis. In experimental diabetes, a large number of studies have documented reductions in nerve blood flow and tandem corrections of nerve blood flow and conduction slowing. A significant proportions, however, of the work can be criticized on the basis of methodology and interpretation. Similarly, not all work has confirmed that reductions of nerve blood flow are an invariable feature of experimental or human diabetic polyneuropathy. Therefore, while there is disagreement as to whether early declines in nerve blood flow "account" for diabetic polyneuropathy, there is unquestioned eveidence of early microangiopathy. Abnormalities of vase nervorum and micorvessels supplying ganglia at the very least develop parallel to and together with changes in neurons, Schwann cells, and axons.
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Affiliation(s)
- Douglas W Zochodne
- Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada T2N 4N1
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Zhang QL, Liu J, Lin PX, Webster HD. Local administration of vasoactive intestinal peptide after nerve transection accelerates early myelination and growth of regenerating axons. J Peripher Nerv Syst 2002; 7:118-27. [PMID: 12090298 DOI: 10.1046/j.1529-8027.2002.02018.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Our goal was to determine whether local injections of vasoactive intestinal peptide (VIP) promote early stages of regeneration after nerve transection. Sciatic nerves were transected bilaterally in 2 groups of 10 adult mice. In the first group, 15 microg (20 microL) of VIP were injected twice daily into the gap between transected ends of the right sciatic nerve for 7 days (4 mice) or 14 days (6 mice). The same number of mice in the second group received placebo injections (20 microL of 0.9% sterile saline) in the same site, twice daily, for the same periods. After 7 days, axon sizes, relationships with Schwann cells and degree of myelination were compared in electron micrographs of transversely sectioned distal ends of proximal stumps. Fourteen days after transection, light and electron microscopy were used to compare and measure axons and myelin sheaths in the transection gap, 2-mm distal to the ends of proximal stumps. Distal ends of VIP-treated proximal stumps contained larger axons 7 days after transection. More axons were in 1:1 relationships with Schwann cells and some of them were surrounded by thin myelin sheaths. In placebo-treated proximal stumps, axons were smaller, few were in 1:1 relationships with Schwann cells and no myelin sheaths were observed. In VIP-treated transection gaps, measurements 14 days after transection showed that larger axons were more numerous and their myelin sheaths were thicker. Our results suggest that in this nerve transection model, local administration of VIP promotes and accelerates early myelination and growth of regenerating axons.
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Affiliation(s)
- Qian-Lin Zhang
- Basic Neurosciences Program, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-4123, USA
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Höke A, Sun HS, Gordon T, Zochodne DW. Do denervated peripheral nerve trunks become ischemic? The impact of chronic denervation on vasa nervorum. Exp Neurol 2001; 172:398-406. [PMID: 11716563 DOI: 10.1006/exnr.2001.7808] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The long-term relationship between the peripheral nerve trunk and its vascular supply, the vasa nervorum, has not been considered in the context of denervation and regeneration. While the microvessels of peripheral nerve are not thought to influence Wallerian degeneration itself, in this work we explored how vasa nervorum respond to denervation of the nerve trunk. Our hypotheses were that the presence of axons had a significant impact on the vasa nervorum and that the absence of reinnervation might eventually lead to an unfavorable ischemic regenerative microenvironment. We studied rat sciatic nerve trunks for up to 6 months following transection and either prevented regeneration or allowed it to proceed. Vasa nervorum were studied in several ways: (i) measurements of local endoneurial blood flow using microelectrode hydrogen clearance polarography; (ii) measurements of erythrocyte flux (flow) in the extrinsic nerve plexus using laser Doppler flowmetry; (iii) India ink perfusion of microvessels in unfixed nerve; (iv) mRNA expression of vascular endothelial growth factor (VEGF) using reverse transcription polymerase chain reaction. Early after injury, there were rises in endoneurial and extrinsic flow, microvessel numbers, and VEGF mRNA expression. Angiogenesis was apparently confined to the epineurial and perineurial compartments. Later, however, there were substantial declines in flow observed in long-term (6-month) denervated sciatic nerve trunks associated with declines in the caliber of new microvessels. Reinnervated sciatic nerves had restored endoneurial blood flow. The findings confirm important relationships between axon presence and local blood flow. Angiogenesis is a feature of the injured peripheral nerve, but long term denervated nerve trunks have declines of flow despite retaining new microvessels.
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Affiliation(s)
- A Höke
- Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta
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