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Suzuki T, Shimizu T, Karnup S, Shimizu N, Ni J, de Groat WC, Yoshimura N. Therapeutic effects of p38 mitogen-activated protein kinase inhibition on hyperexcitability of capsaicin sensitive bladder afferent neurons in mice with spinal cord injury. Life Sci 2023; 325:121738. [PMID: 37121541 PMCID: PMC10225342 DOI: 10.1016/j.lfs.2023.121738] [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: 03/06/2023] [Revised: 04/16/2023] [Accepted: 04/23/2023] [Indexed: 05/02/2023]
Abstract
AIMS Nerve growth factor (NGF) has been implicated as a key molecule of pathology-induced changes in C-fiber afferent nerve excitability, which contributes to the emergence of neurogenic detrusor overactivity due to spinal cord injury (SCI). It is also known that the second messenger signaling pathways activated by NGF utilize p38 Mitogen-Activated Protein Kinase (MAPK). We examined the roles of p38 MAPK on electrophysiological properties of capsaicin sensitive bladder afferent neurons with SCI mice. MAIN METHODS We used female C57BL/6 mice and transected their spinal cord at the Th8/9 level. Two weeks later, continuous administration of p38 MAPK inhibitor (0.51 μg/h, i.t. for two weeks) was started. Bladder afferent neurons were labelled with a fluorescent retrograde tracer, Fast-Blue (FB), injected into the bladder wall three weeks after SCI. Four weeks after SCI, freshly dissociated L6-S1 dorsal root ganglion neurons were prepared and whole cell patch clamp recordings were performed in FB-labelled neurons. After recording action potentials or voltage-gated K+ currents, the sensitivity of each neuron to capsaicin was evaluated. KEY FINDINGS In capsaicin-sensitive FB-labelled neurons, SCI significantly reduced the spike threshold and increased the number of action potentials during 800 ms membrane depolarization. Densities of slow-decaying A-type K+ (KA) and sustained delayed rectifier-type K+ (KDR) currents were significantly reduced by SCI. The reduction of KA, but not KDR, current density was reversed by the treatment with p38 MAPK inhibitor. SIGNIFICANCE P38 MAPK plays an important role in hyperexcitability of capsaicin-sensitive bladder afferent neurons due to the reduction in KA channel activity in SCI mice.
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Affiliation(s)
- Takahisa Suzuki
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America; Department of Urology, Yokohama City University Graduate School of Medicine, Yokohama, Japan; Department of Urology, Kanagawa Rehabilitation Hospital, Atsugi, Japan
| | - Takahiro Shimizu
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
| | - Sergei Karnup
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
| | - Nobutaka Shimizu
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
| | - Jianshu Ni
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
| | - William C de Groat
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
| | - Naoki Yoshimura
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America; Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America.
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Shimizu N, Saito T, Wada N, Hashimoto M, Shimizu T, Kwon J, Cho KJ, Saito M, Karnup S, de Groat WC, Yoshimura N. Molecular Mechanisms of Neurogenic Lower Urinary Tract Dysfunction after Spinal Cord Injury. Int J Mol Sci 2023; 24:7885. [PMID: 37175592 PMCID: PMC10177842 DOI: 10.3390/ijms24097885] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 04/21/2023] [Accepted: 04/22/2023] [Indexed: 05/15/2023] Open
Abstract
This article provides a synopsis of current progress made in fundamental studies of lower urinary tract dysfunction (LUTD) after spinal cord injury (SCI) above the sacral level. Animal models of SCI allowed us to examine the effects of SCI on the micturition control and the underlying neurophysiological processes of SCI-induced LUTD. Urine storage and elimination are the two primary functions of the LUT, which are governed by complicated regulatory mechanisms in the central and peripheral nervous systems. These neural systems control the action of two functional units in the LUT: the urinary bladder and an outlet consisting of the bladder neck, urethral sphincters, and pelvic-floor striated muscles. During the storage phase, the outlet is closed, and the bladder is inactive to maintain a low intravenous pressure and continence. In contrast, during the voiding phase, the outlet relaxes, and the bladder contracts to facilitate adequate urine flow and bladder emptying. SCI disrupts the normal reflex circuits that regulate co-ordinated bladder and urethral sphincter function, leading to involuntary and inefficient voiding. Following SCI, a spinal micturition reflex pathway develops to induce an overactive bladder condition following the initial areflexic phase. In addition, without proper bladder-urethral-sphincter coordination after SCI, the bladder is not emptied as effectively as in the normal condition. Previous studies using animal models of SCI have shown that hyperexcitability of C-fiber bladder afferent pathways is a fundamental pathophysiological mechanism, inducing neurogenic LUTD, especially detrusor overactivity during the storage phase. SCI also induces neurogenic LUTD during the voiding phase, known as detrusor sphincter dyssynergia, likely due to hyperexcitability of Aδ-fiber bladder afferent pathways rather than C-fiber afferents. The molecular mechanisms underlying SCI-induced LUTD are multifactorial; previous studies have identified significant changes in the expression of various molecules in the peripheral organs and afferent nerves projecting to the spinal cord, including growth factors, ion channels, receptors and neurotransmitters. These findings in animal models of SCI and neurogenic LUTD should increase our understanding of pathophysiological mechanisms of LUTD after SCI for the future development of novel therapies for SCI patients with LUTD.
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Affiliation(s)
- Nobutaka Shimizu
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; (N.S.)
- Pelvic Floor Center, Kochi Medical School, Kochi University, Nankoku 783-8505, Japan
| | - Tetsuichi Saito
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; (N.S.)
| | - Naoki Wada
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; (N.S.)
| | - Mamoru Hashimoto
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; (N.S.)
| | - Takahiro Shimizu
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; (N.S.)
- Department of Pharmacology, Kochi Medical School, Kochi University, Nankoku 783-8505, Japan
| | - Joonbeom Kwon
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; (N.S.)
| | - Kang Jun Cho
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; (N.S.)
| | - Motoaki Saito
- Department of Pharmacology, Kochi Medical School, Kochi University, Nankoku 783-8505, Japan
| | - Sergei Karnup
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - William C. de Groat
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Naoki Yoshimura
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; (N.S.)
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
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Potential Roles of Anti-Inflammatory Plant-Derived Bioactive Compounds Targeting Inflammation in Microvascular Complications of Diabetes. Molecules 2022; 27:molecules27217352. [PMID: 36364178 PMCID: PMC9657994 DOI: 10.3390/molecules27217352] [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: 10/08/2022] [Revised: 10/25/2022] [Accepted: 10/26/2022] [Indexed: 12/15/2022] Open
Abstract
Diabetes mellitus (DM) is a group of metabolic disorders, the characteristics of which include chronic hyperglycemia owing to defects in insulin function, insulin secretion, or both. Inflammation plays a crucial role in DM pathogenesis and innate immunity in the development of microvascular complications of diabetes. In addition, hyperglycemia and DM mediate a proinflammatory microenvironment that can result in various microvascular complications, including diabetic nephropathy (DNP), diabetic neuropathy (DN), and diabetic retinopathy (DR). DNP is a major cause of end-stage renal disease. DNP can lead to albuminuria, decreased filtration, mesangium expansion, thickening of the basement membrane, and eventually renal failure. Furthermore, inflammatory cells can accumulate in the interstitium and glomeruli to deteriorate DNP. DN is another most prevalent microvascular complication of DM and the main cause of high mortality, disability, and a poor quality of life. DNs have a wide range of clinical manifestations because of the types of fiber dysfunctions and complex structures of the peripheral nervous system. DR is also a microvascular and multifactorial disease, as well as a major cause of visual impairment globally. Pathogenesis of DR is yet to be fully revealed, however, numerous studies have already confirmed the role of inflammation in the onset and advancement of DR. Despite evidence, and better knowledge regarding the pathogenesis of these microvascular complications of diabetes, there is still a deficiency of effective therapies. Bioactive compounds are mainly derived from plants, and these molecules have promising therapeutic potential. In this review, evidence and molecular mechanisms regarding the role of inflammation in various microvascular complications of diabetes including DNP, DN, and DR, have been summarized. The therapeutic potential of several bioactive compounds derived from plants in the treatment of these microvascular complications of diabetes has also been discussed.
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Faheem M, Khan AU, Shah FA, Li S. Investigation of Natural Compounds for Therapeutic Potential in Streptozotocin-induced Diabetic Neuroinflammation and Neuropathic Pain. Front Pharmacol 2022; 13:1019033. [PMID: 36278164 PMCID: PMC9581174 DOI: 10.3389/fphar.2022.1019033] [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: 08/14/2022] [Accepted: 09/02/2022] [Indexed: 11/15/2022] Open
Abstract
Diabetic neuropathy (DN) is a serious microvascular complication of diabetes mellitus (DM) that impacts the nervous system. Several risk factors are involved in the progression and maintenance of DN-associated pain, such as higher expression of various inflammatory mediators, e.g., tumor necrotic factor-alpha (TNF-α), nuclear factor-kappa B (NF-κB), and cyclo-oxygenase-2 (COX-2). The present research explores the neuroprotective potential of natural isolates, including berbamine, bergapten, and carveol, on the DM-induced neuroinflammation and neurodegeneration that cause neuropathic pain. The study utilized computerized techniques, including computational analysis (a docking assay and a molecular dynamic simulation) before moving to in vivo protocols. Diabetic neuropathy was induced by intraperitonial injection (IP) of streptozotocin (65 mg/kg), and the animal subjects (rats) were kept for 4 weeks for the development of DN. Once diabetic neuropathy was confirmed, the subjects were treated with berbamine, bergapten, and carveol until the sixth week (i.e., 2 weeks of treatment). At the sixth week, the rats were sacrificed, and the sciatic nerve and spinal cord of each was collected for further molecular investigation. Docking and a molecular dynamic simulation (MDS) delivered the information that the natural compounds (berbamine, bergapten, and carveol) were interacting with the selected target protein (i.e., mitogen-activated protein kinase). After IP, it was found that berbamine, bergapten, and carveol had ameliorated mechanical allodynia and thermal hyperalgesia by the 28th day of the study (2 weeks after treatment) without affecting blood glucose levels. Berbamine, bergapten, and carveol markedly elevated the levels of glutathione (GSH) and glutathione s-transferase (GST), in both the sciatic nerve and spinal cord, and also reduced lipid peroxidase (LPO) and nitric oxide (NO). The abovementioned natural isolates reduced pathologic alterations provoked through DN, a finding confirmed through histopathological assays (hematoxylin and eosin staining and immuno-histochemical analysis). Treatment down regulated higher expressions of the inflammatory mediatorcyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), and nuclear factor kappa B (NF-κB), as confirmed by ELISA and polymerase chain reaction (PCR). The outcomes of berbamine, bergapten, and carveol are compared with those of pregabalin as a positive control group. Compared to pregabalin, treatment with the aforementioned three natural compounds improved nociception and reduced hyperalgesic effects, and consequently reduced pain perception and inflammation. Our results suggest the mechanism for the neuro-protective impact of berbamine, bergapten, and carveol might possibly be arbitrated via COX-2, TNF-α, and NF-κB, and regulated by mitogen-activated protein kinase, ultimately ameliorating STZ-provoked, DM-induced neuroinflammation and neurodegeneration, and associated neuropathic pain.
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Affiliation(s)
- Muhammad Faheem
- Riphah Institute of Pharmaceutical Sciences, Riphah International University, Islamabad, Pakistan
| | - Arif-ullah Khan
- Riphah Institute of Pharmaceutical Sciences, Riphah International University, Islamabad, Pakistan
- *Correspondence: Arif-ullah Khan, ; Shupeng Li,
| | - Fawad Ali Shah
- Riphah Institute of Pharmaceutical Sciences, Riphah International University, Islamabad, Pakistan
| | - Shupeng Li
- State Key Laboratory of Oncogenomics, School of Chemical Biology and Biotechnology, Shenzhen Graduate School, Peking University, Shenzhen, China
- *Correspondence: Arif-ullah Khan, ; Shupeng Li,
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Kasimu A, Apizi X, Talifujiang D, Ma X, Fang L, Zhou X. miR-125a-5p in astrocytes attenuates peripheral neuropathy in type 2 diabetic mice through targeting TRAF6. ENDOCRINOL DIAB NUTR 2022; 69:43-51. [PMID: 35232559 DOI: 10.1016/j.endien.2022.01.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 01/14/2021] [Indexed: 06/14/2023]
Abstract
INTRODUCTION Elimination or blocking of astrocytes could ameliorate neuropathic pain in animal models. MiR-125a-5p, expressed in astrocyte derived extracellular vesicles, could mediate astrocyte function to regulate neuron communication. However, the role of miR-125a-5p in DPN (diabetic peripheral neuropathy) remains elusive. MATERIALS AND METHODS Type 2 diabetic mouse (db/db) was used as DPN model, which was confirmed by detection of body weight, blood glucose, mechanical allodynia, thermal hyperalgesia, glial fibrillary acidic protein (GFAP) and monocyte chemoattractant protein-1 (MCP-1). Astrocyte was isolated from db/db mouse and then subjected to high glucose treatment. The expression of miR-125a-5p in db/db mice and high glucose-induced astrocytes was examined by qRT-PCR analysis. Downstream target of miR-125a-5p was clarified by luciferase reporter assay. Tail vein injection of miR-125a-5p mimic into db/db mice was then performed to investigate role of miR-125a-5p on DPN. RESULTS Type 2 diabetic mice showed higher body weight and blood glucose than normal db/m mice. Thermal hyperalgesia and mechanical allodynia were decreased in db/db mouse compared with db/m mouse, while GFAP and MCP-1 were increased in db/db mouse. High glucose treatment enhanced the protein expression of GFAP and MCP-1 in astrocytes. Sciatic nerve tissues in db/db mice and high glucose-induced astrocytes exhibited a decrease in miR-125a-5p. Systemic administration of miR-125a-5p mimic increased mechanical allodynia and thermal hyperalgesia, whereas it decreased GFAP and MCP-1. TRAF6 (tumor necrosis factor receptor associated factor 6) was validated as target of miR-125a-5p. CONCLUSION MiR-125a-5p in astrocytes attenuated DPN in db/db mice by up-regulation of TRAF6, which indicated the potential therapeutic effect.
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Affiliation(s)
- Aziguli Kasimu
- Department of Pain Treatment, People's Hospital of Xinjiang Uygur Autonomous Region, Urumqi City, Xinjiang Uygur Autonomous Region 830001, China
| | - Xierenguli Apizi
- Department of Pain Treatment, People's Hospital of Xinjiang Uygur Autonomous Region, Urumqi City, Xinjiang Uygur Autonomous Region 830001, China
| | - Dilibaier Talifujiang
- Department of Pain Treatment, People's Hospital of Xinjiang Uygur Autonomous Region, Urumqi City, Xinjiang Uygur Autonomous Region 830001, China
| | - Xin Ma
- Department of Pain Treatment, People's Hospital of Xinjiang Uygur Autonomous Region, Urumqi City, Xinjiang Uygur Autonomous Region 830001, China
| | - Liping Fang
- Department of Endocrinology, Honghu People's Hospital, Jingzhou City, Hubei Province 433200, China
| | - Xiangling Zhou
- Department of Neurology, Puren Hospital Affiliated to Wuhan University of Science and Technology, Wuhan City, Hubei Province 430081, China.
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Kasimu A, Apizi X, Talifujiang D, Ma X, Fang L, Zhou X. miR-125a-5p in astrocytes attenuates peripheral neuropathy in type 2 diabetic mice through targeting TRAF6. ENDOCRINOL DIAB NUTR 2021; 69:S2530-0164(21)00104-X. [PMID: 33958320 DOI: 10.1016/j.endinu.2021.01.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/10/2021] [Accepted: 01/14/2021] [Indexed: 01/15/2023]
Abstract
INTRODUCTION Elimination or blocking of astrocytes could ameliorate neuropathic pain in animal models. MiR-125a-5p, expressed in astrocyte derived extracellular vesicles, could mediate astrocyte function to regulate neuron communication. However, the role of miR-125a-5p in DPN (diabetic peripheral neuropathy) remains elusive. MATERIALS AND METHODS Type 2 diabetic mouse (db/db) was used as DPN model, which was confirmed by detection of body weight, blood glucose, mechanical allodynia, thermal hyperalgesia, glial fibrillary acidic protein (GFAP) and monocyte chemoattractant protein-1 (MCP-1). Astrocyte was isolated from db/db mouse and then subjected to high glucose treatment. The expression of miR-125a-5p in db/db mice and high glucose-induced astrocytes was examined by qRT-PCR analysis. Downstream target of miR-125a-5p was clarified by luciferase reporter assay. Tail vein injection of miR-125a-5p mimic into db/db mice was then performed to investigate role of miR-125a-5p on DPN. RESULTS Type 2 diabetic mice showed higher body weight and blood glucose than normal db/m mice. Thermal hyperalgesia and mechanical allodynia were decreased in db/db mouse compared with db/m mouse, while GFAP and MCP-1 were increased in db/db mouse. High glucose treatment enhanced the protein expression of GFAP and MCP-1 in astrocytes. Sciatic nerve tissues in db/db mice and high glucose-induced astrocytes exhibited a decrease in miR-125a-5p. Systemic administration of miR-125a-5p mimic increased mechanical allodynia and thermal hyperalgesia, whereas it decreased GFAP and MCP-1. TRAF6 (tumor necrosis factor receptor associated factor 6) was validated as target of miR-125a-5p. CONCLUSION MiR-125a-5p in astrocytes attenuated DPN in db/db mice by up-regulation of TRAF6, which indicated the potential therapeutic effect.
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Affiliation(s)
- Aziguli Kasimu
- Department of Pain Treatment, People's Hospital of Xinjiang Uygur Autonomous Region, Urumqi City, Xinjiang Uygur Autonomous Region 830001, China
| | - Xierenguli Apizi
- Department of Pain Treatment, People's Hospital of Xinjiang Uygur Autonomous Region, Urumqi City, Xinjiang Uygur Autonomous Region 830001, China
| | - Dilibaier Talifujiang
- Department of Pain Treatment, People's Hospital of Xinjiang Uygur Autonomous Region, Urumqi City, Xinjiang Uygur Autonomous Region 830001, China
| | - Xin Ma
- Department of Pain Treatment, People's Hospital of Xinjiang Uygur Autonomous Region, Urumqi City, Xinjiang Uygur Autonomous Region 830001, China
| | - Liping Fang
- Department of Endocrinology, Honghu People's Hospital, Jingzhou City, Hubei Province 433200, China
| | - Xiangling Zhou
- Department of Neurology, Puren Hospital Affiliated to Wuhan University of Science and Technology, Wuhan City, Hubei Province 430081, China.
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Hagen KM, Ousman SS. Aging and the immune response in diabetic peripheral neuropathy. J Neuroimmunol 2021; 355:577574. [PMID: 33894676 DOI: 10.1016/j.jneuroim.2021.577574] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 04/09/2021] [Accepted: 04/10/2021] [Indexed: 12/27/2022]
Abstract
A large proportion of older individuals with diabetes go on to develop diabetic peripheral neuropathy (DPN). DPN is associated with an increase in inflammatory cells within the peripheral nerve, activation of nuclear factor kappa-light-chain-enhancer of activated B cells and receptors for advanced glycation end products/advanced glycation end products pathways, aberrant cytokine expression, oxidative stress, ischemia, as well as pro-inflammatory changes in the bone marrow; all processes that may be exacerbated with age. We review the immunological features of DPN and discuss whether age-related changes in relevant immunological areas may contribute to age being a risk factor for DPN.
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Affiliation(s)
- Kathleen M Hagen
- Department of Neuroscience, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Shalina S Ousman
- Departments of Clinical Neurosciences and Cell Biology and Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada.
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Yanik BM, Dauch JR, Cheng HT. Interleukin-10 Reduces Neurogenic Inflammation and Pain Behavior in a Mouse Model of Type 2 Diabetes. J Pain Res 2020; 13:3499-3512. [PMID: 33402846 PMCID: PMC7778525 DOI: 10.2147/jpr.s264136] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 11/29/2020] [Indexed: 12/12/2022] Open
Abstract
Purpose Neurogenic inflammation is a major component of chronic neuropathic pain. Previously, we established the db/db mouse as an animal model of painful diabetic neuropathy (PDN) of type 2 diabetes. In the current study, we investigate the roles of interleukin (IL)-10, an anti-inflammatory cytokine, in the development of neurogenic inflammation and pain behavior in db/db mouse. Materials and Methods We first studied IL-10 expression in lumbar dorsal root ganglion (LDRG) neurons of db/db mice using immunohistochemistry, immunoblots, and reverse transcription polymerase chain reaction during the period of pain behavior (from 8 to 16 wk of age). To determine if the reduced IL-10 expression mediates the mechanical allodynia in db/db mice, we administered recombinant mouse IL-10 or saline (control) intraperitoneally to control db/+ and db/db mice starting at 8 wk of age. IL-10 treatment was repeated every other day for 2 wk until the mice reached 10 wk of age. Results During the period of pain behavior, reduction of IL-10 protein and gene expression was detected in LDRG of db/db mice. Treatment with recombinant IL-10, from 8 to 10 wk of age, alleviates pain behaviors in db/db mice without affecting other diabetic parameters. In parallel, IL-10 treatment reduced the upregulation of nerve growth factor (NGF), inducible nitric oxide synthase (iNOS), tumor necrosis factor (TNF)-α, and high-affinity NGF receptor (Trk A) in LDRG, as well as the numbers of iNOS-positive Langerhans cells and CD-68-positive dermal dendritic cells in the hind-foot-pad skin in db/db mice. Conclusion Our findings suggest that the reduction in neuronal IL-10 increases inflammatory phenomena, ultimately contributing to PDN. These results suggest that the dysregulation of cytokine-mediated inflammation contributes to the development of PDN in db/db mice. Targeting this pathophysiologic mechanism could be an effective approach for treating PDN in type 2 diabetes.
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Affiliation(s)
- Brandon M Yanik
- Department of Neurology, University of Michigan Medical Center, Ann Arbor, Michigan, USA
| | - Jacqueline R Dauch
- Department of Neurology, University of Michigan Medical Center, Ann Arbor, Michigan, USA
| | - Hsinlin T Cheng
- Department of Neurology, University of Michigan Medical Center, Ann Arbor, Michigan, USA.,Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Pol O. The role of carbon monoxide, heme oxygenase 1, and the Nrf2 transcription factor in the modulation of chronic pain and their interactions with opioids and cannabinoids. Med Res Rev 2020; 41:136-155. [PMID: 32820550 DOI: 10.1002/med.21726] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 08/03/2020] [Accepted: 08/08/2020] [Indexed: 12/11/2022]
Abstract
Chronic pain and its associated comorbidities are difficult to treat, even when the most potent analgesic compounds are used. Thus, research on new strategies to effectively relieve nociceptive and/or emotional disorders accompanying chronic pain is essential. Several studies have demonstrated the anti-inflammatory and antinociceptive effects of different carbon monoxide-releasing molecules (CO-RMs), inducible heme oxygenase 1 (HO-1), and nuclear factor-2 erythroid factor-2 (Nrf2) transcription factor activators in several models of acute and chronic pain caused by inflammation, nerve injury or diabetes. More recently, the antidepressant and/or anxiolytic effects of several Nrf2 transcription factor inducers were demonstrated in a model of chronic neuropathic pain. These effects are mainly produced by inhibition of oxidative stress, inflammation, glial activation, mitogen-activated protein kinases and/or phosphoinositide 3-kinase/phospho-protein kinase B phosphorylation in the peripheral and/or central nervous system. Other studies also demonstrated that the analgesic effects of opioids and cannabinoids are improved when these drugs are coadministered with CO-RMs, HO-1 or Nrf2 activators in different preclinical pain models and that these improvements are generally mediated by upregulation or prevention of the downregulation of µ-opioid receptors, δ-opioid receptors and/or cannabinoid 2 receptors in the setting of chronic pain. We reviewed all these studies as well as studies on the mechanisms of action underlying the effects of CO-RMs, HO-1, and Nrf2 activators in chronic pain. In summary, activation of the Nrf2/HO-1/carbon monoxide signaling pathway alone and/or in combination with the administration of specific analgesics is a valid strategy for the treatment of chronic pain and some associated emotional disorders.
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Affiliation(s)
- Olga Pol
- Grup de Neurofarmacologia Molecular, Institut d'Investigació Biomèdica Sant Pau, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
- Grup de Neurofarmacologia Molecular, Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
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Mai L, Zhu X, Huang F, He H, Fan W. p38 mitogen-activated protein kinase and pain. Life Sci 2020; 256:117885. [PMID: 32485175 DOI: 10.1016/j.lfs.2020.117885] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 05/23/2020] [Accepted: 05/28/2020] [Indexed: 12/18/2022]
Abstract
Inflammatory and neuropathic pain is initiated by tissue inflammation and nerve injury, respectively. Both are characterized by increased activity in the peripheral and central nervous system, where multiple inflammatory cytokines and other active molecules activate different signaling pathways that involve in the development and/or maintenance of pain. P38 mitogen-activated protein kinase (MAPK) is one member of the MAPK family, which is activated in neurons and glia and contributes importantly to inflammatory and neuropathic pain. The aim of this review is to summarize the latest advances made about the implication of p38 MAPK signaling cascade in pain. It can deepen our understanding of the molecular mechanisms of pain and may help to offer new targets for pain treatment.
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Affiliation(s)
- Lijia Mai
- Department of Anesthesiology, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangzhou 510080, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510080, China
| | - Xiao Zhu
- The Marine Biomedical Research Institute, Guangdong Medical University, Zhanjiang 524023, China
| | - Fang Huang
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510080, China
| | - Hongwen He
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510080, China
| | - Wenguo Fan
- Department of Anesthesiology, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangzhou 510080, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510080, China.
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Tu Y, Chen Z, Zhang F, Di Z, Zhang J, Cai L. Gene Expression Profiling of the Sciatic Nerve in Streptozotocin-Induced Diabetic Rats with Peripheral Neuropathy. J Diabetes Res 2020; 2020:5283284. [PMID: 32566679 PMCID: PMC7256683 DOI: 10.1155/2020/5283284] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 04/13/2020] [Accepted: 04/23/2020] [Indexed: 01/23/2023] Open
Abstract
AIMS To investigate the candidate biomarkers and molecular mechanisms involved in the early phase of experimental diabetic peripheral neuropathy (DPN). METHODS Diabetes in Sprague-Dawley rats was induced with streptozotocin (STZ) treatment, followed with neurological tests and histological examinations to assess the neuropathic symptoms of DPN. Microarray was performed on the sciatic nerve tissues from control rats and DPN rats at then6th week after diabetes induction, and differentially expressed genes (DEGs) between them were identified and applied for further bioinformatic analyses. RESULTS Experimental DPN rats were successfully constructed, presenting significantly decreased withdrawal threshold and motor nerve conduction velocity, and typical histological changes in the sciatic nerve. 597 DEGs (186 up- and 411 downregulated) were identified in DPN rats. DEGs from the 3 most highly connected clusters in the protein-protein interaction network were enriched for biological processes or pathways such as "cell division," "cell cycle," "protein phosphorylation," "chemokine signaling pathway," "neuropeptide signaling pathway," "response to drug," "cellular response to insulin stimulus," "PPAR signaling pathway," and "glycerophospholipid metabolism." Thirteen genes were identified as the hub DEGs in the PPI network. Eleven transcriptional factors (TFs) targeting 9 of the 13 hub DEGs were predicted. CONCLUSIONS The present study identified a pool of candidate biomarkers such as Cdk1, C3, Mapk12, Agt, Adipoq, Cxcl2, and Mmp9 and molecular mechanisms which may be involved in the early phase of experimental DPN. The findings provide clues for exploring new strategies for the early diagnosis and treatment of DPN.
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Affiliation(s)
- Yiji Tu
- Department of Joint Surgery, Ningbo Sixth Hospital, Ningbo 315040, China
| | - Zenggan Chen
- Department of Orthopedic Surgery, Zhongshan Hospital, Fudan University, Shanghai 200030, China
| | - Feng Zhang
- Joseph M. Still Burn and Reconstruction Center, Jackson, Mississippi 39201, USA
| | - Zhenglin Di
- Department of Joint Surgery, Ningbo Sixth Hospital, Ningbo 315040, China
| | - Junhui Zhang
- Department of Joint Surgery, Ningbo Sixth Hospital, Ningbo 315040, China
| | - Li Cai
- Department of Ophthalmology, Ningbo Eye Hospital, Ningbo 315040, China
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12
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Specialized pro-resolving mediators in diabetes: novel therapeutic strategies. Clin Sci (Lond) 2019; 133:2121-2141. [DOI: 10.1042/cs20190067] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 10/07/2019] [Accepted: 10/08/2019] [Indexed: 02/07/2023]
Abstract
AbstractDiabetes mellitus (DM) is an important metabolic disorder characterized by persistent hyperglycemia resulting from inadequate production and secretion of insulin, impaired insulin action, or a combination of both. Genetic disorders and insulin receptor disorders, environmental factors, lifestyle choices and toxins are key factors that contribute to DM. While it is often referred to as a metabolic disorder, modern lifestyle choices and nutrient excess induce a state of systemic chronic inflammation that results in the increased production and secretion of inflammatory cytokines that contribute to DM. It is chronic hyperglycemia and the low-grade chronic-inflammation that underlies the development of microvascular and macrovascular complications leading to damage in a number of tissues and organs, including eyes, vasculature, heart, nerves, and kidneys. Improvements in the management of risk factors have been beneficial, including focus on intensified glycemic control, but most current approaches only slow disease progression. Even with recent studies employing SGLT2 inhibitors demonstrating protection against cardiovascular and kidney diseases, kidney function continues to decline in people with established diabetic kidney disease (DKD). Despite the many advances and a greatly improved understanding of the pathobiology of diabetes and its complications, there remains a major unmet need for more effective therapeutics to prevent and reverse the chronic complications of diabetes. More recently, there has been growing interest in the use of specialised pro-resolving mediators (SPMs) as an exciting therapeutic strategy to target diabetes and the chronic complications of diabetes.
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13
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Shimizu N, Wada N, Shimizu T, Suzuki T, Kurobe M, Kanai AJ, de Groat WC, Hashimoto M, Hirayama A, Uemura H, Yoshimura N. Role of p38 MAP kinase signaling pathways in storage and voiding dysfunction in mice with spinal cord injury. Neurourol Urodyn 2019; 39:108-115. [PMID: 31579964 DOI: 10.1002/nau.24170] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 09/07/2019] [Indexed: 11/09/2022]
Abstract
AIM To investigate the role of p38 MAP kinase in lower urinary tract dysfunction in mice with spinal cord injury (SCI). METHODS Cystometry and external urethral sphincter-electromyography were performed under an awake condition in 4-week SCI female mice. Two weeks after SCI, a catheter connected to an osmotic pump filled with a p38 mitogen-activated protein kinase (MAPK) inhibitor or artificial cerebrospinal fluid (CSF) was implanted into the intrathecal space of L6-S1 spinal cord for continuous intrathecal instillation at infusion rate of 0.51 μL/h for 2 weeks before the urodynamic study. L6 dorsal root ganglia were then removed from CSF and p38 MAPK inhibitor-treated SCI mice as well as from CSF-treated normal (spinal intact) mice to evaluate the levels of transient receptor potential cation channel subfamily V member 1 (TRPV1), tumor necrosis factor-α (TNF-α), and inducible nitric oxide synthase (iNOS) transcripts by real-time polymerase chain reaction. RESULTS In p38 MAPK inhibitor-treated SCI mice, nonvoiding contractions during bladder filling, bladder capacity, and post-void residual volume were significantly reduced while micturition pressure and voiding efficiency were significantly increased in comparison to these measurements in CSF-treated SCI mice. The expression of TRPV1, TNF-α, and iNOS messenger RNA was increased in SCI mice compared with expression in spinal intact mice and significantly decreased after p38 MAPK inhibitor treatment. CONCLUSIONS The p38 MAPK signaling pathway in bladder sensory neurons or in the spinal cord plays an important role in storage and voiding problems such as detrusor overactivity and inefficient voiding after SCI.
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Affiliation(s)
- Nobutaka Shimizu
- Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania.,Department of Urology, Faculty of Medicine, Kindai University, Osaka-Sayama, Japan
| | - Naoki Wada
- Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Takahiro Shimizu
- Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Takahisa Suzuki
- Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Masahiro Kurobe
- Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Anthony J Kanai
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - William C de Groat
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Mamoru Hashimoto
- Department of Urology, Faculty of Medicine, Kindai University, Osaka-Sayama, Japan
| | - Akihide Hirayama
- Department of Urology, Faculty of Medicine, Kindai University Nara Hospital, Nara, Japan
| | - Hirotsugu Uemura
- Department of Urology, Faculty of Medicine, Kindai University, Osaka-Sayama, Japan
| | - Naoki Yoshimura
- Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania.,Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
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Identify the Key Active Ingredients and Pharmacological Mechanisms of Compound XiongShao Capsule in Treating Diabetic Peripheral Neuropathy by Network Pharmacology Approach. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2019; 2019:5801591. [PMID: 31210774 PMCID: PMC6532326 DOI: 10.1155/2019/5801591] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 03/20/2019] [Accepted: 04/15/2019] [Indexed: 02/07/2023]
Abstract
Compound XiongShao Capsule (CXSC), a traditional herb mixture, has shown significant clinical efficacy against diabetic peripheral neuropathy (DPN). However, its multicomponent and multitarget features cause difficulty in deciphering its molecular mechanisms. Our study aimed to identify the key active ingredients and potential pharmacological mechanisms of CXSC in treating DPN by network pharmacology and provide scientific evidence of its clinical efficacy. CXSC active ingredients were identified from both the Traditional Chinese Medicine Systems Pharmacology database, with parameters of oral bioavailability ≥ 30% and drug-likeness ≥ 0.18, and the Herbal Ingredients' Targets (HIT) database. The targets of those active ingredients were identified using ChemMapper based on 3D-structure similarity and using HIT database. DPN-related genes were acquired from microarray dataset GSE95849 and five widely used databases (TTD, Drugbank, KEGG, DisGeNET, and OMIM). Next, we obtained candidate targets with therapeutic effects against DPN by mapping active ingredient targets and DPN-related genes and identifying the proteins interacting with those candidate targets using STITCH 5.0. We constructed an “active ingredients-candidate targets-proteins” network using Cytoscape 3.61 and identified key active ingredients and key targets in the network. We identified 172 active ingredients in CXSC, 898 targets of the active ingredients, 110 DPN-related genes, and 38 candidate targets with therapeutic effects against DPN. Three key active ingredients, namely, quercetin, kaempferol, and baicalein, and 25 key targets were identified. Next, we input all key targets into ClueGO plugin for KEGG enrichment and molecular function analyses. The AGE-RAGE signaling pathway in diabetic complications and MAP kinase activity were determined as the main KEGG pathway and molecular function involved, respectively. We determined quercetin, kaempferol, and baicalein as the key active ingredients of CXSC and the AGE-RAGE signaling pathway and MAP kinase activity as the main pharmacological mechanisms of CXSC against DPN, proving the clinical efficacy of CXSC against DPN.
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15
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Shillo P, Sloan G, Greig M, Hunt L, Selvarajah D, Elliott J, Gandhi R, Wilkinson ID, Tesfaye S. Painful and Painless Diabetic Neuropathies: What Is the Difference? Curr Diab Rep 2019; 19:32. [PMID: 31065863 PMCID: PMC6505492 DOI: 10.1007/s11892-019-1150-5] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
PURPOSE OF REVIEW The prevalence of diabetes mellitus and its chronic complications are increasing to epidemic proportions. This will unfortunately result in massive increases in diabetic distal symmetrical polyneuropathy (DPN) and its troublesome sequelae, including disabling neuropathic pain (painful-DPN), which affects around 25% of patients with diabetes. Why these patients develop neuropathic pain, while others with a similar degree of neuropathy do not, is not clearly understood. This review will look at recent advances that may shed some light on the differences between painful and painless-DPN. RECENT FINDINGS Gender, clinical pain phenotyping, serum biomarkers, brain imaging, genetics, and skin biopsy findings have been reported to differentiate painful- from painless-DPN. Painful-DPN seems to be associated with female gender and small fiber dysfunction. Moreover, recent brain imaging studies have found neuropathic pain signatures within the central nervous system; however, whether this is the cause or effect of the pain is yet to be determined. Further research is urgently required to develop our understanding of the pathogenesis of pain in DPN in order to develop new and effective mechanistic treatments for painful-DPN.
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Affiliation(s)
- Pallai Shillo
- Diabetes Research Unit, Royal Hallamshire Hospital, Sheffield Teaching Hospitals NHS Foundation Trust, Glossop Road, Sheffield, S10 2JF UK
| | - Gordon Sloan
- Diabetes Research Unit, Royal Hallamshire Hospital, Sheffield Teaching Hospitals NHS Foundation Trust, Glossop Road, Sheffield, S10 2JF UK
| | - Marni Greig
- Diabetes Research Unit, Royal Hallamshire Hospital, Sheffield Teaching Hospitals NHS Foundation Trust, Glossop Road, Sheffield, S10 2JF UK
| | - Leanne Hunt
- Diabetes Research Unit, Royal Hallamshire Hospital, Sheffield Teaching Hospitals NHS Foundation Trust, Glossop Road, Sheffield, S10 2JF UK
| | - Dinesh Selvarajah
- Department of Oncology and Human Metabolism, University of Sheffield, Sheffield, UK
| | - Jackie Elliott
- Department of Oncology and Human Metabolism, University of Sheffield, Sheffield, UK
| | - Rajiv Gandhi
- Diabetes Research Unit, Royal Hallamshire Hospital, Sheffield Teaching Hospitals NHS Foundation Trust, Glossop Road, Sheffield, S10 2JF UK
| | | | - Solomon Tesfaye
- Diabetes Research Unit, Royal Hallamshire Hospital, Sheffield Teaching Hospitals NHS Foundation Trust, Glossop Road, Sheffield, S10 2JF UK
- Department of Oncology and Human Metabolism, University of Sheffield, Sheffield, UK
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16
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Warwick CA, Shutov LP, Shepherd AJ, Mohapatra DP, Usachev YM. Mechanisms underlying mechanical sensitization induced by complement C5a: the roles of macrophages, TRPV1, and calcitonin gene-related peptide receptors. Pain 2019; 160:702-711. [PMID: 30507785 PMCID: PMC6377341 DOI: 10.1097/j.pain.0000000000001449] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The complement system significantly contributes to the development of inflammatory and neuropathic pain, but the underlying mechanisms are poorly understood. Recently, we identified the signaling pathway responsible for thermal hypersensitivity induced by the complement system component C5a. Here, we examine the mechanisms of another important action of C5a, induction of mechanical hypersensitivity. We found that intraplantar injection of C5a produced a dose-dependent mechanical sensitization and that this effect was blocked by chemogenetic ablation of macrophages in both male and female mice. Knockout of TRPV1 or pretreatment with the TRPV1 antagonists, AMG9810 or 5'-iodoresiniferatoxin (5'-IRTX), significantly reduced C5a-induced mechanical sensitization. Notably, local administration of 5'-IRTX 90 minutes after C5a injection resulted in a slow, but complete, reversal of mechanical sensitization, indicating that TRPV1 activity was required for maintaining C5a-induced mechanical hypersensitivity. This slow reversal suggests that neurogenic inflammation and neuropeptide release may be involved. Indeed, pretreatment with a calcitonin gene-related peptide (CGRP) receptor antagonist (but not an antagonist of the neurokinin 1 receptor) prevented C5a-induced mechanical sensitization. Furthermore, intraplantar injection of CGRP produced significant mechanical sensitization in both wild-type and TRPV1 knockout mice. Taken together, these findings suggest that C5a produces mechanical sensitization by initiating macrophage-to-sensory-neuron signaling cascade that involves activation of TRPV1 and CGRP receptor as critical steps in this process.
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Affiliation(s)
- Charles A. Warwick
- Department of Pharmacology and Iowa Neuroscience Institute, University of Iowa, Iowa City, IA 52242
| | - Leonid P. Shutov
- Department of Pharmacology and Iowa Neuroscience Institute, University of Iowa, Iowa City, IA 52242
| | - Andrew J. Shepherd
- Department of Anesthesiology, Washington University Pain Center, Washington University School of Medicine, St. Louis, MO 63110
| | - Durga P. Mohapatra
- Department of Anesthesiology, Washington University Pain Center, Washington University School of Medicine, St. Louis, MO 63110
| | - Yuriy M. Usachev
- Department of Pharmacology and Iowa Neuroscience Institute, University of Iowa, Iowa City, IA 52242
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Dewanjee S, Das S, Das AK, Bhattacharjee N, Dihingia A, Dua TK, Kalita J, Manna P. Molecular mechanism of diabetic neuropathy and its pharmacotherapeutic targets. Eur J Pharmacol 2018; 833:472-523. [DOI: 10.1016/j.ejphar.2018.06.034] [Citation(s) in RCA: 117] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 06/15/2018] [Accepted: 06/26/2018] [Indexed: 02/07/2023]
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18
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Tsantoulas C, Laínez S, Wong S, Mehta I, Vilar B, McNaughton PA. Hyperpolarization-activated cyclic nucleotide-gated 2 (HCN2) ion channels drive pain in mouse models of diabetic neuropathy. Sci Transl Med 2018; 9:eaam6072. [PMID: 28954930 DOI: 10.1126/scitranslmed.aam6072] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 02/22/2017] [Accepted: 09/06/2017] [Indexed: 01/12/2023]
Abstract
Diabetic patients frequently suffer from continuous pain that is poorly treated by currently available analgesics. We used mouse models of type 1 and type 2 diabetes to investigate a possible role for the hyperpolarization-activated cyclic nucleotide-gated 2 (HCN2) ion channels as drivers of diabetic pain. Blocking or genetically deleting HCN2 channels in small nociceptive neurons suppressed diabetes-associated mechanical allodynia and prevented neuronal activation of second-order neurons in the spinal cord in mice. In addition, we found that intracellular cyclic adenosine monophosphate (cAMP), a positive HCN2 modulator, is increased in somatosensory neurons in an animal model of painful diabetes. We propose that the increased intracellular cAMP drives diabetes-associated pain by facilitating HCN2 activation and consequently promoting repetitive firing in primary nociceptive nerve fibers. Our results suggest that HCN2 may be an analgesic target in the treatment of painful diabetic neuropathy.
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Affiliation(s)
- Christoforos Tsantoulas
- Wolfson Centre for Age-Related Diseases, King's College London, Guy's Campus, London Bridge, London SE1 1UL, UK
| | - Sergio Laínez
- Wolfson Centre for Age-Related Diseases, King's College London, Guy's Campus, London Bridge, London SE1 1UL, UK
| | - Sara Wong
- Wolfson Centre for Age-Related Diseases, King's College London, Guy's Campus, London Bridge, London SE1 1UL, UK
| | - Ishita Mehta
- Wolfson Centre for Age-Related Diseases, King's College London, Guy's Campus, London Bridge, London SE1 1UL, UK
| | - Bruno Vilar
- Wolfson Centre for Age-Related Diseases, King's College London, Guy's Campus, London Bridge, London SE1 1UL, UK
| | - Peter A McNaughton
- Wolfson Centre for Age-Related Diseases, King's College London, Guy's Campus, London Bridge, London SE1 1UL, UK.
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de Lima ME, Colpo AZC, Rosa H, Salgueiro ACF, da Silva MP, Noronha DS, Santamaría A, Folmer V. Ilex paraguariensis extracts reduce blood glucose, peripheral neuropathy and oxidative damage in male mice exposed to streptozotocin. J Funct Foods 2018. [DOI: 10.1016/j.jff.2018.02.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
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20
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Zhang C, Ward J, Dauch JR, Tanzi RE, Cheng HT. Cytokine-mediated inflammation mediates painful neuropathy from metabolic syndrome. PLoS One 2018; 13:e0192333. [PMID: 29408929 PMCID: PMC5800683 DOI: 10.1371/journal.pone.0192333] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 12/29/2017] [Indexed: 12/29/2022] Open
Abstract
Painful neuropathy (PN) is a prevalent condition in patients with metabolic syndrome (MetS). However, the pathogenic mechanisms of metabolic syndrome-associated painful neuropathy (MetSPN) remain unclear. In the current study, high-fat-fed mice (HF mice) were used to study MetSPN. HF mice developed MetS phenotypes, including increased body weight, elevated plasma cholesterol levels, and insulin resistance in comparison with control-fat-fed (CF) mice. Subsequently, HF mice developed mechanical allodynia and thermal hyperalgesia in hind paws after 8 wk of diet treatment. These pain behaviors coincided with increased densities of nociceptive epidermal nerve fibers and inflammatory cells such as Langerhans cells and macrophages in hind paw skin. To study the effect of MetS on profiles of cytokine expression in HF mice, we used a multiplex cytokine assay to study the protein expression of 12 pro-inflammatory and anti-inflammatory cytokines in dorsal root ganglion and serum samples. This method detected the elevated levels of proinflammatory cytokines, including tumor necrosis factor (TNF)-α, and interleukin (IL)-6, IL-1β as well as reduced anti-inflammatory IL-10 in lumbar dorsal root ganglia (LDRG) of HF mice. Intraperitoneal administration of IL-10 reduced the upregulation of pro-inflammatory cytokines and alleviated pain behaviors in HF mice without affecting MetS phenotypes. Our findings suggested targeting HF-induced cytokine dysregulation could be an effective strategy for treating MetSPN.
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Affiliation(s)
- Can Zhang
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Joseph Ward
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Jacqueline R. Dauch
- Department of Neurology, University of Michigan Medical Center, Ann Arbor, Michigan, United States of America
| | - Rudolph E. Tanzi
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Hsinlin T. Cheng
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- * E-mail:
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The Inhibitory Effects of Cobalt Protoporphyrin IX and Cannabinoid 2 Receptor Agonists in Type 2 Diabetic Mice. Int J Mol Sci 2017; 18:ijms18112268. [PMID: 29143802 PMCID: PMC5713238 DOI: 10.3390/ijms18112268] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 10/25/2017] [Accepted: 10/27/2017] [Indexed: 01/19/2023] Open
Abstract
The activation of the transcription factor Nrf2 inhibits neuropathy and modulates the activity of delta-opioid receptors (DOR) in type 2 diabetic mice but the impact of Nrf2/HO-1 pathway on the antinociceptive actions of cannabinoid 2 receptors (CB2R) has not been assessed. Using male mice BKS.Cg-m+/+Leprdb/J (db/db) we investigated if treatment with cobalt protoporphyrin IX (CoPP), an HO-1 inductor, inhibited mechanical allodynia, hyperglycemia and obesity associated to type 2 diabetes. The antinociceptive effects of JWH-015 and JWH-133 (CB2R agonists) administered with and without CoPP or sulforaphane (SFN), a Nrf2 transcription factor activator, have been also evaluated. The expression of Nrf2, HO-1, NAD(P)H: quinone oxidoreductase 1 (NQO1) and c-Jun N-terminal kinase (JNK) in sciatic nerve and that of the CB2R on the dorsal root ganglia from animals treated with CoPP and/or SFN were assessed. CoPP treatment inhibited allodynia, hyperglycemia and body weight gain in db/db mice by enhancing HO-1/NQO1 levels and reducing JNK phosphorylation. Both CoPP and SFN improved the antiallodynic effects of JWH-015 and JWH-133 and expression of CB2R in db/db mice. Therefore, we concluded that the activation of antioxidant Nrf2/HO-1 pathway potentiate the effects of CB2R agonists and might be suitable for the treatment of painful neuropathy linked to type 2 diabetes.
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Nasiry D, khalatbary AR, Ahmadvand H, Talebpour Amiri F, Akbari E. Protective effects of methanolic extract of Juglans regia L. leaf on streptozotocin-induced diabetic peripheral neuropathy in rats. Altern Ther Health Med 2017; 17:476. [PMID: 28969623 PMCID: PMC5625610 DOI: 10.1186/s12906-017-1983-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 09/22/2017] [Indexed: 12/20/2022]
Abstract
Background Oxidative stress has a pivotal role in the pathogenesis and development of diabetic peripheral neuropathy (DPN), the most common and debilitating complications of diabetes mellitus. There is accumulating evidence that Juglans regia L. (GRL) leaf extract, a rich source of phenolic components, has hypoglycemic and antioxidative properties. This study aimed to determine the protective effects of Juglans regia L. leaf extract against streptozotocin-induced diabetic neuropathy in rat. Methods The DPN rat model was generated by intraperitoneal injection of a single 55 mg/kg dose of streptozotocin (STZ). A subset of the STZ-induced diabetic rats intragastically administered with GRL leaf extract (200 mg/kg/day) before or after the onset of neuropathy, whereas other diabetic rats received only isotonic saline as the same volume of GRL leaf extract. To evaluate the effects of GRL leaf extract on the diabetic neuropathy various parameters, including histopathology and immunohistochemistry of apoptotic and inflammatory factors were assessed along with nociceptive and biochemical assessments. Results Degeneration of the sciatic nerves which was detected in the STZ-diabetic rats attenuated after GRL leaf extract administration. Greater caspase-3, COX-2, and iNOS expression could be detected in the STZ-diabetic rats, which were significantly attenuated after GRL leaf extract administration. Also, attenuation of lipid peroxidation and nociceptive response along with improved antioxidant status in the sciatic nerve of diabetic rats were detected after GRL leaf extract administration. In other word, GRL leaf extract ameliorated the behavioral and structural indices of diabetic neuropathy even after the onset of neuropathy, in addition to blood sugar reduction. Conclusion Our results suggest that GRL leaf extract exert preventive and curative effects against STZ-induced diabetic neuropathy in rats which might be due to its antioxidant, anti-inflammatory, and antiapoptotic properties. Graphical abstract Protection against neuropathy![]()
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23
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The Complement System Component C5a Produces Thermal Hyperalgesia via Macrophage-to-Nociceptor Signaling That Requires NGF and TRPV1. J Neurosci 2017; 36:5055-70. [PMID: 27147658 DOI: 10.1523/jneurosci.3249-15.2016] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 03/21/2016] [Indexed: 12/31/2022] Open
Abstract
UNLABELLED The complement cascade is a principal component of innate immunity. Recent studies have underscored the importance of C5a and other components of the complement system in inflammatory and neuropathic pain, although the underlying mechanisms are largely unknown. In particular, it is unclear how the complement system communicates with nociceptors and which ion channels and receptors are involved. Here we demonstrate that inflammatory thermal and mechanical hyperalgesia induced by complete Freund's adjuvant was accompanied by C5a upregulation and was markedly reduced by C5a receptor (C5aR1) knock-out or treatment with the C5aR1 antagonist PMX53. Direct administration of C5a into the mouse hindpaw produced strong thermal hyperalgesia, an effect that was absent in TRPV1 knock-out mice, and was blocked by the TRPV1 antagonist AMG9810. Immunohistochemistry of mouse plantar skin showed prominent expression of C5aR1 in macrophages. Additionally, C5a evoked strong Ca(2+) mobilization in macrophages. Macrophage depletion in transgenic macrophage Fas-induced apoptosis mice abolished C5a-dependent thermal hyperalgesia. Examination of inflammatory mediators following C5a injection revealed a rapid upregulation of NGF, a mediator known to sensitize TRPV1. Preinjection of an NGF-neutralizing antibody or Trk inhibitor GNF-5837 prevented C5a-induced thermal hyperalgesia. Notably, NGF-induced thermal hyperalgesia was unaffected by macrophage depletion. Collectively, these results suggest that complement fragment C5a induces thermal hyperalgesia by triggering macrophage-dependent signaling that involves mobilization of NGF and NGF-dependent sensitization of TRPV1. Our findings highlight the importance of macrophage-to-neuron signaling in pain processing and identify C5a, NGF, and TRPV1 as key players in this cross-cellular communication. SIGNIFICANCE STATEMENT This study provides mechanistic insight into how the complement system, a key component of innate immunity, regulates the development of pain hypersensitivity. We demonstrate a crucial role of the C5a receptor, C5aR1, in the development of inflammatory thermal and mechanical sensitization. By focusing on the mechanisms of C5a-induced thermal hyperalgesia, we show that this process requires recruitment of macrophages and initiation of macrophage-to-nociceptor signaling. At the molecular level, we demonstrate that this signaling depends on NGF and is mediated by the heat-sensitive nociceptive channel TRPV1. This deeper understanding of how immune cells and neurons interact to regulate pain processing is expected to facilitate mechanism-based approaches in the development of new analgesics.
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McDonnell C, Leánez S, Pol O. The induction of the transcription factor Nrf2 enhances the antinociceptive effects of delta-opioid receptors in diabetic mice. PLoS One 2017; 12:e0180998. [PMID: 28700700 PMCID: PMC5507309 DOI: 10.1371/journal.pone.0180998] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Accepted: 06/23/2017] [Indexed: 12/21/2022] Open
Abstract
The involvement of heme oxygenase 1 (HO-1) in the modulation of the antinociceptive effects of opioids in type 1 diabetes has been demonstrated but the role played by the transcription factor Nrf2 in the regulation of painful neuropathy and in the effects and expression of δ-opioid receptors (DOR) in type 2 diabetes, has not been studied. In male BKS.Cg-m+/+Leprdb/J (db/db) mice, the anti-allodynic effects produced by a Nrf2 transcription factor activator, sulforaphane (SFN) administered alone and combined with two DOR agonists, [d-Pen(2),d-Pen(5)]-Enkephalin (DPDPE) and (+)-4-[(αR)-α-((2S,5R)-4-Allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N diethylbenzamide (SNC-80), were evaluated. The effects of SFN on glucose levels and body weight as well as on the proteins levels of Nrf2, HO-1, NAD(P)H: quinone oxidoreductase 1 (NQO1), MAPKs (JNK) and DOR in sciatic nerve from db/db mice were also assessed. This study showed that the administration of SFN dose dependently reversed mechanical allodynia, reduced hyperglycemia and body weight gain associated to type 2 diabetes and significantly increased the anti-allodynic effects of DPDPE and SNC-80 in db/db mice. This treatment normalized the down regulation of Nrf2 and NQO1 and enhanced the protein levels of HO-1 in db/db mice. Moreover, the administration of SFN also inhibited the JNK phosphorylation and DOR down-regulation in the sciatic nerve of diabetic mice. Our data indicated that SFN treatment is effective in reversing mechanical allodynia and enhancing DOR antinociceptive effects in db/db mice which effects might be mediated by activating Nrf2 signaling, reducing hyperglycemia, inhibiting JNK phosphorylation and avoiding DOR down-regulation in the sciatic nerve of these animals. These results propose SFN, alone and/or combined with DOR agonists, as interesting approaches for the treatment of painful diabetic neuropathy associated to type 2 diabetes in mice.
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MESH Headings
- Animals
- Benzamides/pharmacology
- Blood Glucose/drug effects
- Blood Glucose/metabolism
- Blotting, Western
- Body Weight/drug effects
- Body Weight/genetics
- Body Weight/physiology
- Diabetes Mellitus, Experimental/genetics
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Type 2/genetics
- Diabetes Mellitus, Type 2/metabolism
- Diabetic Neuropathies/metabolism
- Enkephalin, D-Penicillamine (2,5)-/pharmacology
- Hyperalgesia/metabolism
- Isothiocyanates/pharmacology
- Male
- Mice
- NF-E2-Related Factor 2/genetics
- NF-E2-Related Factor 2/metabolism
- Piperazines/pharmacology
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/genetics
- Receptors, Opioid, delta/metabolism
- Sulfoxides
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Affiliation(s)
- Christina McDonnell
- Grup de Neurofarmacologia Molecular, Institut d’Investigació Biomèdica Sant Pau, Barcelona, Spain
- Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Sergi Leánez
- Grup de Neurofarmacologia Molecular, Institut d’Investigació Biomèdica Sant Pau, Barcelona, Spain
- Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Olga Pol
- Grup de Neurofarmacologia Molecular, Institut d’Investigació Biomèdica Sant Pau, Barcelona, Spain
- Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
- * E-mail:
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25
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HCN2 ion channels: basic science opens up possibilities for therapeutic intervention in neuropathic pain. Biochem J 2016; 473:2717-36. [DOI: 10.1042/bcj20160287] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 05/18/2016] [Indexed: 01/22/2023]
Abstract
Nociception — the ability to detect painful stimuli — is an invaluable sense that warns against present or imminent damage. In patients with chronic pain, however, this warning signal persists in the absence of any genuine threat and affects all aspects of everyday life. Neuropathic pain, a form of chronic pain caused by damage to sensory nerves themselves, is dishearteningly refractory to drugs that may work in other types of pain and is a major unmet medical need begging for novel analgesics. Hyperpolarisation-activated cyclic nucleotide (HCN)-modulated ion channels are best known for their fundamental pacemaker role in the heart; here, we review data demonstrating that the HCN2 isoform acts in an analogous way as a ‘pacemaker for pain’, in that its activity in nociceptive neurons is critical for the maintenance of electrical activity and for the sensation of chronic pain in pathological pain states. Pharmacological block or genetic deletion of HCN2 in sensory neurons provides robust pain relief in a variety of animal models of inflammatory and neuropathic pain, without any effect on normal sensation of acute pain. We discuss the implications of these findings for our understanding of neuropathic pain pathogenesis, and we outline possible future opportunities for the development of efficacious and safe pharmacotherapies in a range of chronic pain syndromes.
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26
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Abstract
Painful neuropathy, like the other complications of diabetes, is a growing healthcare concern. Unfortunately, current treatments are of variable efficacy and do not target underlying pathogenic mechanisms, in part because these mechanisms are not well defined. Rat and mouse models of type 1 diabetes are frequently used to study diabetic neuropathy, with rats in particular being consistently reported to show allodynia and hyperalgesia. Models of type 2 diabetes are being used with increasing frequency, but the current literature on the progression of indices of neuropathic pain is variable and relatively few therapeutics have yet been developed in these models. While evidence for spontaneous pain in rodent models is sparse, measures of evoked mechanical, thermal and chemical pain can provide insight into the pathogenesis of the condition. The stocking and glove distribution of pain tantalizingly suggests that the generator site of neuropathic pain is found within the peripheral nervous system. However, emerging evidence demonstrates that amplification in the spinal cord, via spinal disinhibition and neuroinflammation, and also in the brain, via enhanced thalamic activity or decreased cortical inhibition, likely contribute to the pathogenesis of painful diabetic neuropathy. Several potential therapeutic strategies have emerged from preclinical studies, including prophylactic treatments that intervene against underlying mechanisms of disease, treatments that prevent gains of nociceptive function, treatments that suppress enhancements of nociceptive function, and treatments that impede normal nociceptive mechanisms. Ongoing challenges include unraveling the complexity of underlying pathogenic mechanisms, addressing the potential disconnect between the perceived location of pain and the actual pain generator and amplifier sites, and finding ways to identify which mechanisms operate in specific patients to allow rational and individualized choice of targeted therapies.
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Affiliation(s)
- Corinne A Lee-Kubli
- Graduate School of Biomedical Sciences, Sanford-Burnham Institute for Molecular Medicine, La Jolla, CA, USA; Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Nigel A Calcutt
- Department of Pathology, University of California San Diego, La Jolla, CA, USA.
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27
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Abstract
Diabetic neuropathies (DNs) are one of the most prevalent chronic complications of diabetes and a major cause of disability, high mortality, and poor quality of life. Given the complex anatomy of the peripheral nervous system and types of fiber dysfunction, DNs have a wide spectrum of clinical manifestations. The treatment of DNs continues to be challenging, likely due to the complex pathogenesis that involves an array of systemic and cellular imbalances in glucose and lipids metabolism. These lead to the activation of various biochemical pathways, including increased oxidative/nitrosative stress, activation of the polyol and protein kinase C pathways, activation of polyADP ribosylation, and activation of genes involved in neuronal damage, cyclooxygenase-2 activation, endothelial dysfunction, altered Na(+)/K(+)-ATPase pump function, impaired C-peptide-related signaling pathways, endoplasmic reticulum stress, and low-grade inflammation. This review summarizes current evidence regarding the role of low-grade inflammation as a potential therapeutic target for DNs.
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Affiliation(s)
- Rodica Pop-Busui
- Department of Internal Medicine, Division of Metabolism, Metabolism Endocrinology and Diabetes, University of Michigan, 5329 Brehm Tower, 1000 Wall Street, Ann Arbor, MI, 48105, USA.
| | - Lynn Ang
- Department of Internal Medicine, Division of Metabolism, Metabolism Endocrinology and Diabetes, University of Michigan, 5329 Brehm Tower, 1000 Wall Street, Ann Arbor, MI, 48105, USA.
| | - Crystal Holmes
- The Division of Metabolism, Endocrinology and Diabetes, Dominos Farms, Lobby C, Suite 1300 24 Frank Lloyd Wright Drive, PO Box 451, Ann Arbor, MI, 48106-0451, USA.
| | - Katherine Gallagher
- Department of Surgery, Section of Vascular Surgery, University of Michigan Health System, 1500 East Medical Center Dr, SPC 5867, Ann Arbor, MI, 48109, USA.
| | - Eva L Feldman
- Department of Neurology, University of Michigan, 5017 AATBSRB, 109 Zina Pitcher Place, Ann Arbor, MI, 48109-2200, USA.
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Association Between Tumor Necrosis Factor-α and Diabetic Peripheral Neuropathy in Patients with Type 2 Diabetes: a Meta-Analysis. Mol Neurobiol 2016; 54:983-996. [PMID: 26797519 DOI: 10.1007/s12035-016-9702-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 01/05/2016] [Indexed: 12/13/2022]
Abstract
Tumor necrosis factor-α (TNF-α) is a cell signaling protein involved in systemic inflammation, and is also an important cytokine in the acute phase reaction. Several studies suggested a possible association between TNF-α and diabetic peripheral neuropathy (DPN) in type 2 diabetic patients, but no accurate conclusion was available. A systematic review and meta-analysis of observational studies was performed to comprehensively assess the association between serum TNF-α levels and DPN in type 2 diabetic patients. We searched Pubmed, Web of Science, Embase, and China Biology Medicine (CMB) databases for eligible studies. Study-specific data were combined using meta-analysis. Fourteen studies were finally included into the meta-analysis, which involved a total of 2650 participants. Meta-analysis showed that there were obviously increased serum TNF-α levels in DPN patients compared with type 2 diabetic patients without DPN (standard mean difference [SMD] = 1.203, 95 % CI 0.795-1.611, P < 0.001). There were also obviously increased levels of serum TNF-α in diabetic patients with DPN when compared with healthy controls (SMD = 2.364, 95 % CI 1.333-3.394, P < 0.001). In addition, there were increased serum TNF-α levels in painful DPN patients compared with painless DPN patients (SMD = 0.964, 95 % CI 0.237-1.690, P = 0.009). High level of serum TNF-α was significantly associated with increased risk of DPN in patients with type 2 diabetes (odds ratio [OR] = 2.594, 95 % CI 1.182-5.500, P = 0.017). Increased serum levels of TNF-α was not associated with increased risk of painful DPN in patients with type 2 diabetes (OR = 2.486, 95 % CI 0.672-9.193, P = 0.172). Sensitivity analysis showed that there was no obvious change in the pooled estimates when omitting single study by turns. Type 2 diabetic patients with peripheral neuropathy have obviously increased serum TNF-α levels than type 2 diabetic patients without peripheral neuropathy and healthy controls, and high level of serum TNF-α may be associated with increased risk of peripheral neuropathy independently. Further prospective cohort studies are needed to assess the association between TNF-α and DPN.
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29
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Nasrallah R, Hassouneh R, Hébert RL. PGE2, Kidney Disease, and Cardiovascular Risk: Beyond Hypertension and Diabetes. J Am Soc Nephrol 2015; 27:666-76. [PMID: 26319242 DOI: 10.1681/asn.2015050528] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
An important measure of cardiovascular health is obtained by evaluating the global cardiovascular risk, which comprises a number of factors, including hypertension and type 2 diabetes, the leading causes of illness and death in the world, as well as the metabolic syndrome. Altered immunity, inflammation, and oxidative stress underlie many of the changes associated with cardiovascular disease, diabetes, and the metabolic syndrome, and recent efforts have begun to elucidate the contribution of PGE2 in these events. This review summarizes the role of PGE2 in kidney disease outcomes that accelerate cardiovascular disease, highlights the role of cyclooxygenase-2/microsomal PGE synthase 1/PGE2 signaling in hypertension and diabetes, and outlines the contribution of PGE2 to other aspects of the metabolic syndrome, particularly abdominal adiposity, dyslipidemia, and atherogenesis. A clearer understanding of the role of PGE2 could lead to new avenues to improve therapeutic options and disease management strategies.
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Affiliation(s)
- Rania Nasrallah
- Department of Cellular and Molecular Medicine, Kidney Research Centre, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Ramzi Hassouneh
- Department of Cellular and Molecular Medicine, Kidney Research Centre, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Richard L Hébert
- Department of Cellular and Molecular Medicine, Kidney Research Centre, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
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30
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Yoon H, Thakur V, Isham D, Fayad M, Chattopadhyay M. Moderate exercise training attenuates inflammatory mediators in DRG of Type 1 diabetic rats. Exp Neurol 2015; 267:107-14. [PMID: 25783659 DOI: 10.1016/j.expneurol.2015.03.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 01/22/2015] [Accepted: 03/08/2015] [Indexed: 01/12/2023]
Abstract
Painful neuropathy is a long-term and difficult to treat complication of diabetes that affects 25% of diabetic patients and interferes with their quality of life. Unfortunately, available medical treatments are relatively ineffective due to dependency and addiction. Emerging research indicates that moderate-to-vigorous physical activity provides health-related benefits. However, adequate data is not available to determine whether regular exercise would prevent or delay the development of painful neuropathy in subjects with Type 1 diabetes. This study demonstrates the significance of moderate exercise in the amelioration of pain in animals with Type 1 diabetes after 6weeks of exercise paradigm. After initial acclimatization, streptozotocin-diabetic animals were placed in motorized running wheels for 60minperday, for five days a week for 6weeks starting at one week after diabetes. A growing body of evidence suggests that the release of proinflammatory cytokines plays an important role in the development and persistence of pain. This study demonstrates that moderate exercise increases the expression of inhibitory neurotransmitter enkephalin and also reduces the presence of a number of proinflammatory cytokines in the dorsal root ganglia (DRG), subsequently impeding the development of neuropathy along with a decrease in the voltage gated ion channels in the DRG. Overall, the study suggests that exercise may provide an alternate route of treatment of painful neuropathy in Type 1 diabetic subjects by decreasing the use of pain medications, thereby providing a more useful and efficient way for pain management.
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Affiliation(s)
- HaeJee Yoon
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Vikram Thakur
- Center of Excellence in Diabetes and Obesity, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX, USA
| | - Danielle Isham
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Mona Fayad
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Munmun Chattopadhyay
- Center of Excellence in Diabetes and Obesity, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX, USA.
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31
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Newton VL, Ali S, Duddy G, Whitmarsh AJ, Gardiner NJ. Targeting apoptosis signalling kinase-1 (ASK-1) does not prevent the development of neuropathy in streptozotocin-induced diabetic mice. PLoS One 2014; 9:e107437. [PMID: 25329046 PMCID: PMC4199525 DOI: 10.1371/journal.pone.0107437] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 08/18/2014] [Indexed: 12/25/2022] Open
Abstract
Apoptosis signal-regulating kinase-1 (ASK1) is a mitogen-activated protein 3 kinase (MAPKKK/MAP3K) which lies upstream of the stress-activated MAPKs, JNK and p38. ASK1 may be activated by a variety of extracellular and intracellular stimuli. MAP kinase activation in the sensory nervous system as a result of diabetes has been shown in numerous preclinical and clinical studies. As a common upstream activator of both p38 and JNK, we hypothesised that activation of ASK1 contributes to nerve dysfunction in diabetic neuropathy. We therefore wanted to characterize the expression of ASK1 in sensory neurons, and determine whether the absence of functional ASK1 would protect against the development of neuropathy in a mouse model of experimental diabetes. ASK1 mRNA and protein is constitutively expressed by multiple populations of sensory neurons of the adult mouse lumbar DRG. Diabetes was induced in male C57BL/6 and transgenic ASK1 kinase-inactive (ASK1n) mice using streptozotocin. Levels of ASK1 do not change in the DRG, spinal cord, or sciatic nerve following induction of diabetes. However, levels of ASK2 mRNA increase in the spinal cord at 4 weeks of diabetes, which could represent a future target for this field. Neither motor nerve conduction velocity deficits, nor thermal or mechanical hypoalgesia were prevented or ameliorated in diabetic ASK1n mice. These results suggest that activation of ASK1 is not responsible for the nerve deficits observed in this mouse model of diabetic neuropathy.
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Affiliation(s)
- Victoria L. Newton
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Sumia Ali
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Graham Duddy
- Platform Technology and Sciences, GlaxoSmithKline, Stevenage, Herts, United Kingdom
| | - Alan J. Whitmarsh
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Natalie J. Gardiner
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
- * E-mail:
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32
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Maier Ortmann KL, Chattopadhyay M. Decrease in neuroimmune activation by HSV-mediated gene transfer of TNFα soluble receptor alleviates pain in rats with diabetic neuropathy. Brain Behav Immun 2014; 41:144-51. [PMID: 24880032 PMCID: PMC4167461 DOI: 10.1016/j.bbi.2014.05.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 05/12/2014] [Accepted: 05/13/2014] [Indexed: 12/20/2022] Open
Abstract
The mechanisms of diabetic painful neuropathy are complicated and comprise of peripheral and central pathophysiological phenomena. A number of proinflammatory cytokines are involved in this process. Tumor necrosis factor α (TNF-α) is considered to be one of the major contributors of neuropathic pain. In order to explore the potential role of inflammation in the peripheral nervous system of Type 1 diabetic animals with painful neuropathy, we investigated whether TNF-α is a key inflammatory mediator to the diabetic neuropathic pain and whether continuous delivery of TNFα soluble receptor from damaged axons achieved by HSV vector mediated transduction of DRG would block or alter the pain perception in animals with diabetic neuropathy. Diabetic animals exhibited changes in threshold of mechanical and thermal pain perception compared to control rats and also demonstrated increases in TNFα in the DRG, spinal cord dorsal horn, sciatic nerve and in the foot skin, 6 weeks after the onset of diabetes. Therapeutic approaches by HSV mediated expression of p55 TNF soluble receptor significantly attenuated the diabetes-induced hyperalgesia and decreased the expression of TNFα with reduction in the phosphorylation of p38MAPK in the spinal cord dorsal horn and DRG. The overall outcome of this study suggests that neuroinflammatory activation in the peripheral nervous system may be involved in the pathogenesis of painful neuropathy in Type 1 diabetes which can be alleviated by local expression of HSV vector expressing p55 TNF soluble receptor.
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Affiliation(s)
- Kathryn L. Maier Ortmann
- Department of Neurology, University of Michigan, Ann Arbor, MI USA,University of Texas, Health Science Center at Houston, Houston, TX, USA
| | - Munmun Chattopadhyay
- Department of Neurology, University of Michigan, USA; VA Ann Arbor Healthcare System, Ann Arbor, MI, USA.
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33
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Radu BM, Dumitrescu DI, Marin A, Banciu DD, Iancu AD, Selescu T, Radu M. Advanced type 1 diabetes is associated with ASIC alterations in mouse lower thoracic dorsal root ganglia neurons. Cell Biochem Biophys 2014; 68:9-23. [PMID: 23723009 DOI: 10.1007/s12013-013-9678-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Acid-sensing ion channels (ASICs) from dorsal root ganglia (DRG) neurons are proton sensors during ischemia and inflammation. Little is known about their role in type 1 diabetes (T1D). Our study was focused on ASICs alterations determined by advanced T1D status. Primary neuronal cultures were obtained from lower (T9-T12) thoracic DRG neurons from Balb/c and TCR-HA(+/-)/Ins-HA(+/-) diabetic male mice (16 weeks of age). Patch-clamp recordings indicate a change in the number of small DRG neurons presenting different ASIC-type currents. Multiple molecular sites of ASICs are distinctly affected in T1D, probably due to particular steric constraints for glycans accessibility to the active site: (i) ASIC1 current inactivates faster, while ASIC2 is slower; (ii) PcTx1 partly reverts diabetes effects against ASIC1- and ASIC2-inactivations; (iii) APETx2 maintains unaltered potency against ASIC3 current amplitude, but slows ASIC3 inactivation. Immunofluorescence indicates opposite regulation of different ASIC transcripts while qRT-PCR shows that ASIC mRNA ranking (ASIC2 > ASIC1 > ASIC3) remains unaltered. In conclusion, our study has identified biochemical and biophysical ASIC changes in lower thoracic DRG neurons due to advanced T1D. As hypoalgesia is present in advanced T1D, ASICs alterations might be the cause or the consequence of diabetic insensate neuropathy.
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Affiliation(s)
- Beatrice Mihaela Radu
- Section of Anatomy and Histology, Department of Neurological, Neuropsychological, Morphological and Movement Sciences, University of Verona, Strada Le Grazie 8, 37134, Verona, Italy
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Abstract
More than half of all patients with diabetes develop neuropathic disorders affecting the distal sensory and/or motor nerves, or autonomic or cranial nerve functions. Glycemic control can decrease the incidence of neuropathy but is not adequate alone to prevent or treat the disease. This chapter introduces diabetic neuropathy with a morphological description of the disease then describes our current understanding of metabolic and molecular mechanisms that contribute to neurovascular dysfunctions. Key mechanisms include glucose and lipid imbalances and insulin resistance that are interconnected via oxidative stress, inflammation, and altered gene expression. These complex interactions should be considered for the development of new treatment strategies against the onset or progression of neuropathy. Advances in understanding the combined metabolic stressors and the novel study of epigenetics suggest new therapeutic targets to combat this morbid and intractable disease affecting millions of patients with type 1 or type 2 diabetes.
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35
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Xu X, Chen H, Ling BY, Xu L, Cao H, Zhang YQ. Extracellular signal-regulated protein kinase activation in spinal cord contributes to pain hypersensitivity in a mouse model of type 2 diabetes. Neurosci Bull 2013; 30:53-66. [PMID: 24194231 DOI: 10.1007/s12264-013-1387-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 05/03/2013] [Indexed: 12/28/2022] Open
Abstract
Painful peripheral neuropathy is a common complication of diabetes mellitus. The symptom of pain can become a major factor that decreases the quality of life of patients with diabetes, while effective treatment is lacking. In the present study, we aimed to investigate the changes of pain threshold in the early stage of diabetes in db/db mice, an animal model of type 2 diabetes mellitus, and the underlying molecular mechanisms. We found that (1) db/db mice (with a leptin receptor-null mutation and characterized by obesity and hyperglycemia) showed hypersensitivity to mechanical and thermal stimuli at the early stage of diabetes; (2) phosphorylated extracellular signal-regulated kinase (pERK), but not total ERK in the spinal cord and dorsal root ganglia in db/db mice significantly increased compared with wild-type mice. The increased pERK immunoreactivity occurred in both NeuN-expressing neurons and GFAP-expressing astrocytes, but not in Iba-1-expressing microglia; (3) both single and consecutive (for 5 days) intrathecal injections of U0126 (2 nmol per day), a selective MEK (an ERK kinase) inhibitor beginning at 8 weeks of age, attenuated the bilateral mechanical allodynia in the von-Frey test and heat hyperalgesia in Hargreave's test; and (4) db/db mice also displayed increased nocifensive behavior during the formalin test, and this was blocked by intrathecal injection of U0126. Also, the expression of pERK1 and pERK2 was upregulated following the formalin injection. Our results suggested that the activation of ERK in spinal neurons and astrocytes is correlated with pain hypersensitivity of the type 2 diabetes animal model. Inhibiting the ERK pathway may provide a new therapy for pain control in type 2 diabetes.
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Affiliation(s)
- Xiang Xu
- Department of Endocrinology, Wuxi People's Hospital, Nanjing Medical University, Wuxi, 214023, China
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36
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Pop-Busui R, Lu J, Brooks MM, Albert S, Althouse AD, Escobedo J, Green J, Palumbo P, Perkins BA, Whitehouse F, Jones TLZ. Impact of glycemic control strategies on the progression of diabetic peripheral neuropathy in the Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) Cohort. Diabetes Care 2013; 36:3208-15. [PMID: 23757426 PMCID: PMC3781573 DOI: 10.2337/dc13-0012] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE The Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) trial demonstrated similar long-term clinical effectiveness of insulin-sensitizing (IS) versus insulin-providing (IP) treatments for type 2 diabetes on cardiovascular outcomes in a cohort with documented coronary artery disease. We evaluated the effects of randomized glycemic control strategy (IS vs. IP) on the prevalence and incidence of diabetic peripheral neuropathy (DPN). RESEARCH DESIGN AND METHODS DPN (defined as Michigan Neuropathy Screening Instrument [MNSI] clinical examination score>2) was assessed at baseline and yearly for 4 years. DPN prevalence and incidence were compared by intention-to-treat modeling by logistic generalized estimating equation models for prevalence and Kaplan-Meier estimates and Cox regression models for incidence rates. RESULTS Results are reported for 2,159 BARI 2D participants (70% males) with valid baseline and at least one follow-up MNSI score (mean age 62±9 years, mean HbA1c 7.7±1.6%, diabetes duration 10±9 years). There were no differences in the prevalence of DPN between the IS and the IP groups throughout the 4 years of follow-up. In 1,075 BARI 2D participants with no DPN at baseline, the 4-year cumulative incidence rate of DPN was significantly lower in the IS (66%) than in the IP (72%) strategy group (P=0.02), which remained significant after adjusting for the in-trial HbA1c (P=0.04). In subgroup analyses, IS strategy had a greater benefit in men (hazard ratio 0.75 [99% CI 0.58-0.99], P<0.01). CONCLUSIONS Among patients with type 2 diabetes followed for up to 4 years during BARI 2D, a glycemic control therapy with IS significantly reduced the incidence of DPN compared with IP therapy and may add further benefit for men.
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37
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Moon JY, Roh DH, Yoon SY, Kang SY, Choi SR, Kwon SG, Choi HS, Han HJ, Beitz AJ, Lee JH. Sigma-1 receptor-mediated increase in spinal p38 MAPK phosphorylation leads to the induction of mechanical allodynia in mice and neuropathic rats. Exp Neurol 2013; 247:383-91. [PMID: 23333567 DOI: 10.1016/j.expneurol.2013.01.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 12/22/2012] [Accepted: 01/08/2013] [Indexed: 12/30/2022]
Abstract
The direct activation of the spinal sigma-1 receptor (Sig-1R) produces mechanical allodynia (MA) and thermal hyperalgesia (TH) in mice. In addition, the blockade of the spinal Sig-1R prevents the induction of MA, but not TH in chronic constriction injury (CCI)-induced neuropathic rats. The present study was designed to investigate whether the increase in spinal p38 MAPK phosphorylation (p-p38 MAPK) mediates Sig-1R-induced MA or TH in mice and the induction of MA in neuropathic rats. MA and TH were evaluated using von Frey filaments and a hot-plate apparatus, respectively. Neuropathic pain was produced by CCI of the right sciatic nerve in rats. Western blot assay and immunohistochemistry were performed to determine the changes of p-p38 MAPK expression in the spinal cord. Intrathecal (i.t.) injection of PRE084, a selective Sig-1R agonist, into naïve mice time-dependently increased the expression of p-p38 MAPK, which was blocked by pretreatment with BD1047, a Sig-1R antagonist. I.t. pretreatment with SB203580, a p38 MAPK inhibitor also dose-dependently inhibited PRE084-induced MA, whereas TH induction was not affected. In CCI rats, i.t. injection of BD1047 during the induction phase (postoperative days 0 to 5) reduced the CCI-induced increase in p-p38 MAPK. In addition, i.t. SB203580 treatment during the induction phase also suppressed the development of CCI-induced MA, but not TH. Conversely, i.t. SB203580 treatment during the maintenance phase (postoperative days 15 to 20) had no effect on CCI-induced MA or TH. These results demonstrate that the increase in spinal p-p38 MAPK is closely associated with the induction of Sig-1R mediated MA, but not TH. Sigma-1 receptor modulation of p-p38 MAPK also plays an important role in the induction, but not the maintenance, of MA in neuropathic pain.
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Affiliation(s)
- Ji-Young Moon
- Department of Veterinary Physiology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, Republic of Korea
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Van Dam PS, Cotter MA, Bravenboer B, Cameron NE. Pathogenesis of diabetic neuropathy: focus on neurovascular mechanisms. Eur J Pharmacol 2013; 719:180-186. [PMID: 23872412 DOI: 10.1016/j.ejphar.2013.07.017] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2013] [Accepted: 07/11/2013] [Indexed: 02/08/2023]
Abstract
Neuropathies of the peripheral and autonomic nervous systems affect up to half of all people with diabetes, and are major risk factors for foot ulceration and amputation. The aetiology is multifactorial: metabolic changes in diabetes may directly affect neural tissue, but importantly, neurodegenerative changes are precipitated by compromised nerve vascular supply. Experiments in animal models of diabetic neuropathy suggest that similar metabolic sequelae affect neurons and vasa nervorum endothelium. These include elevated polyol pathway activity, oxidative stress, the formation of advanced glycation and lipoxidation end products, and various pro-inflammatory changes such as elevated protein kinase C, nuclear factor κB and p38 mitogen activated protein kinase signalling. These mechanisms do not work in isolation but strongly interact in a mutually facilitatory fashion. Nitrosative stress and the induction of the enzyme poly (ADP-ribose) polymerase form one important link between physiological stressors such as reactive oxygen species and the pro-inflammatory mechanisms. Recently, evidence points to endoplasmic stress and the unfolded protein response as forming another crucial link. This review focuses on the aetiopathogenesis of neurovascular changes in diabetic neuropathy, elucidated in animal studies, and on putative therapeutic targets the majority of which have yet to be tested for efficacy in clinical trials.
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Affiliation(s)
- P Sytze Van Dam
- Onze Lieve Vrouwe Gasthuis, Department of internal Medicine, PO Box 95500, 1090HM Amsterdam, The Netherlands
| | - Mary A Cotter
- School of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland UK
| | | | - Norman E Cameron
- School of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland UK.
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Dauch JR, Bender DE, Luna-Wong LA, Hsieh W, Yanik BM, Kelly ZA, Cheng HT. Neurogenic factor-induced Langerhans cell activation in diabetic mice with mechanical allodynia. J Neuroinflammation 2013; 10:64. [PMID: 23672639 PMCID: PMC3685572 DOI: 10.1186/1742-2094-10-64] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 04/25/2013] [Indexed: 01/09/2023] Open
Abstract
Background Langerhans cells (LCs) are antigen-presenting dendritic cells located in the skin. It has been reported that LC activation is associated with painful diabetic neuropathy (PDN); however, the mechanism of LC activation is still unclear. Methods The db/db mouse, a rodent model of PDN, was used to study the roles of LCs in the development of PDN in type 2 diabetes. Hind foot pads from db/db and control db/+ mice from 5 to 24 weeks of age (encompassing the period of mechanical allodynia development and its abatement) were collected and processed for immunohistochemistry studies. LCs were identified with immunohistochemistry using an antibody against CD207 (Langerin). The intraepidermal nerve fibers and subepidermal nerve plexus were identified by immunohistochemistry of protein gene product 9.5 (PGP 9.5) and tropomyosin-receptor kinase (Trk) A, the high affinity nerve growth factor receptor. Results CD207-positive LCs increased in the db/db mouse during the period of mechanical allodynia, from 8 to 10 weeks of age, in both the epidermis and subepidermal plexus. At 16 weeks of age, when mechanical allodynia diminishes, LC populations were reduced in the epidermis and subepidermal plexus. Epidermal LCs (ELCs) were positive for Trk A. Subepidermal LCs (SLCs) were positive for CD68, suggesting that they are immature LCs. Additionally, these SLCs were positive for the receptor of advanced glycation end products (RAGE) and were in direct contact with TNF-α-positive nerve fibers in the subepidermal nerve plexus during the period of mechanical allodynia. Intrathecal administration of SB203580, a p38 kinase inhibitor, significantly reduced mechanical allodynia, TNF-α expression in the subepidermal plexus, and increased both ELC and SLC populations during the period of mechanical allodynia. Conclusions Our data support the hypothesis that increased LC populations in PDN are activated by p38-dependent neurogenic factors and may be involved in the pathogenesis of PDN.
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Affiliation(s)
- Jacqueline R Dauch
- Department of Neurology, University of Michigan Medical Center, Ann Arbor, MI, USA
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40
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Increased nerve growth factor signaling in sensory neurons of early diabetic rats is corrected by electroacupuncture. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:652735. [PMID: 23710226 PMCID: PMC3654322 DOI: 10.1155/2013/652735] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Revised: 03/18/2013] [Accepted: 03/20/2013] [Indexed: 12/12/2022]
Abstract
Diabetic polyneuropathy (DPN), characterized by early hyperalgesia and increased nerve growth factor (NGF), evolves in late irreversible neuropathic symptoms with reduced NGF support to sensory neurons. Electroacupuncture (EA) modulates NGF in the peripheral nervous system, being effective for the treatment of DPN symptoms. We hypothesize that NGF plays an important pathogenic role in DPN development, while EA could be useful in the therapy of DPN by modulating NGF expression/activity. Diabetes was induced in rats by streptozotocin (STZ) injection. One week after STZ, EA was started and continued for three weeks. NGF system and hyperalgesia-related mediators were analyzed in the dorsal root ganglia (DRG) and in their spinal cord and skin innervation territories. Our results show that four weeks long diabetes increased NGF and NGF receptors and deregulated intracellular signaling mediators of DRG neurons hypersensitization; EA in diabetic rats decreased NGF and NGF receptors, normalized c-Jun N-terminal and p38 kinases activation, decreased transient receptor potential vanilloid-1 ion channel, and possibly activated the nuclear factor kappa-light-chain-enhancer of activated B cells (Nf-κB). In conclusion, NGF signaling deregulation might play an important role in the development of DPN. EA represents a supportive tool to control DPN development by modulating NGF signaling in diabetes-targeted neurons.
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Petho G, Reeh PW. Sensory and signaling mechanisms of bradykinin, eicosanoids, platelet-activating factor, and nitric oxide in peripheral nociceptors. Physiol Rev 2013; 92:1699-775. [PMID: 23073630 DOI: 10.1152/physrev.00048.2010] [Citation(s) in RCA: 191] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Peripheral mediators can contribute to the development and maintenance of inflammatory and neuropathic pain and its concomitants (hyperalgesia and allodynia) via two mechanisms. Activation or excitation by these substances of nociceptive nerve endings or fibers implicates generation of action potentials which then travel to the central nervous system and may induce pain sensation. Sensitization of nociceptors refers to their increased responsiveness to either thermal, mechanical, or chemical stimuli that may be translated to corresponding hyperalgesias. This review aims to give an account of the excitatory and sensitizing actions of inflammatory mediators including bradykinin, prostaglandins, thromboxanes, leukotrienes, platelet-activating factor, and nitric oxide on nociceptive primary afferent neurons. Manifestations, receptor molecules, and intracellular signaling mechanisms of the effects of these mediators are discussed in detail. With regard to signaling, most data reported have been obtained from transfected nonneuronal cells and somata of cultured sensory neurons as these structures are more accessible to direct study of sensory and signal transduction. The peripheral processes of sensory neurons, where painful stimuli actually affect the nociceptors in vivo, show marked differences with respect to biophysics, ultrastructure, and equipment with receptors and ion channels compared with cellular models. Therefore, an effort was made to highlight signaling mechanisms for which supporting data from molecular, cellular, and behavioral models are consistent with findings that reflect properties of peripheral nociceptive nerve endings. Identified molecular elements of these signaling pathways may serve as validated targets for development of novel types of analgesic drugs.
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Affiliation(s)
- Gábor Petho
- Pharmacodynamics Unit, Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Pécs, Pécs, Hungary
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Mizukoshi K, Sasaki M, Izumi Y, Miura M, Watanabe M, Amaya F. Activation of p38 mitogen-activated protein kinase in the dorsal root ganglion contributes to pain hypersensitivity after plantar incision. Neuroscience 2013; 234:77-87. [PMID: 23298852 DOI: 10.1016/j.neuroscience.2013.01.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2012] [Revised: 12/13/2012] [Accepted: 01/01/2013] [Indexed: 01/18/2023]
Abstract
BACKGROUND The phosphorylation of p38 mitogen-activated protein kinase (MAPK) in the dorsal root ganglion (DRG) promotes primary afferent sensitization. The role of p38MAPK signaling in the DRG in the pathogenesis of plantar incision hyperalgesia has not been investigated. RESULTS Levels of phosphorylated p38MAPK (p-p38MAPK) obviously increased in the DRG after plantar incision. Unmyelinated and myelinated DRG neurons that express p-p38MAPK contained small to medium cell bodies, suggesting that p-p38MAPK expression is induced in neurons with C- and Aδ-fibers. The p-p38MAPK inhibitors FR167653 or SB203580 inhibited incision-induced mechanical hypersensitivity and spontaneous pain behavior. The systemic administration of tumor necrosis factor-α (TNF-α) inhibitor prevented subsequent incision-induced activation of p38MAPK in the DRG and alleviated mechanical hypersensitivity after the incision. CONCLUSIONS p38MAPK signaling in the DRG plays a crucial role in the development of primary afferent sensitization and pain behavior caused by plantar incision.
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Affiliation(s)
- K Mizukoshi
- Department of Anesthesiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
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43
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Stavniichuk R, Obrosov AA, Drel VR, Nadler JL, Obrosova IG, Yorek MA. 12/15-Lipoxygenase inhibition counteracts MAPK phosphorylation in mouse and cell culture models of diabetic peripheral neuropathy. ACTA ACUST UNITED AC 2013; 3. [PMID: 24175152 DOI: 10.4236/jdm.2013.33015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Increased mitogen-activated protein kinase (MAPK) phosphorylation has been detected in peripheral nerve of human subjects and animal models with diabetes as well as high-glucose exposed human Schwann cells, and have been implicated in diabetic peripheral neuropathy. In our recent studies, leukocytetype 12/15-lipoxygenase inhibition or gene deficiency alleviated large and small nerve fiber dysfunction, but not intraepidermal nerve fiber loss in streptozotocin-diabetic mice. METHODS To address a mechanism we evaluated the potential for pharmacological 12/15-lipoxygenase inhibition to counteract excessive MAPK phosphorylation in mouse and cell culture models of diabetic neuropathy. C57Bl6/J mice were made diabetic with streptozotocin and maintained with or without the 12/15-lipoxygenase inhibitor cinnamyl-3,4-dihydroxy-α-cyanocinnamate (CDC). Human Schwann cells were cultured in 5.5 mM or 30 mM glucose with or without CDC. RESULTS 12(S) HETE concentrations (ELISA), as well as 12/15-lipoxygenase expression and p38 MAPK, ERK, and SAPK/JNK phosphorylation (all by Western blot analysis) were increased in the peripheral nerve and spinal cord of diabetic mice as well as in high glucose-exposed human Schwann cells. CDC counteracted diabetes-induced increase in 12(S)HETE concentrations (a measure of 12/15-lipoxygenase activity), but not 12/15-lipoxygenase overexpression, in sciatic nerve and spinal cord. The inhibitor blunted excessive p38 MAPK and ERK, but not SAPK/ JNK, phosphorylation in sciatic nerve and high glucose exposed human Schwann cells, but did not affect MAPK, ERK, and SAPK/JNK phosphorylation in spinal cord. CONCLUSION 12/15-lipoxygenase inhibition counteracts diabetes related MAPK phosphorylation in mouse and cell culture models of diabetic neuropathy and implies that 12/15-lipoxygenase inhibitors may be an effective treatment for diabetic peripheral neuropathy.
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Affiliation(s)
- Roman Stavniichuk
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, USA
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Dauch JR, Yanik BM, Hsieh W, Oh SS, Cheng HT. Neuron-astrocyte signaling network in spinal cord dorsal horn mediates painful neuropathy of type 2 diabetes. Glia 2012; 60:1301-15. [PMID: 22573263 DOI: 10.1002/glia.22349] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 04/13/2012] [Accepted: 04/17/2012] [Indexed: 12/13/2022]
Abstract
Activation of the neuronal-glial network in the spinal cord dorsal horn (SCDH) mediates various chronic painful conditions. We studied spinal neuronal-astrocyte signaling interactions involved in the maintenance of painful diabetic neuropathy (PDN) in type 2 diabetes. We used the db/db mouse, an animal model for PDN of type 2 diabetes, which develops mechanical allodynia from 6 to 12 wk of age. In this study, enhanced substance P expression was detected in the presynaptic sensory fibers innervating lamina I-III in the lumbar SCDH (LSCDH) of the db/db mouse at 10 wk of age. This phenomenon is associated with enhanced spinal ERK1/2 phosphorylation in projection sensory neurons and regional astrocyte activation. In addition, peak phosphorylation of the NR1 subunit of N-methyl-D-aspartate receptor (NMDAR), along with upregulation of neuronal and inducible nitric oxide synthase (nNOS and iNOS) expression were detected in diabetic mice. Expression of nNOS and iNOS was detected in both interneurons and astrocytes in lamina I-III of the LSCDH. Treatment with MK801, an NMDAR inhibitor, inhibited mechanical allodynia, ERK1/2 phosphorylation, and nNOS and iNOS upregulation in diabetic mice. MK801 also reduced astrocytosis and glial acidic fibrillary protein upregulation in db/db mice. In addition, N(G)-nitro-L-arginine methyl ester (L-NAME), a nonspecific NOS inhibitor, had similar effects on NMDAR signaling and NOS expression. These results suggest that nitric oxide from surrounding interneurons and astrocytes interacts with NMDAR-dependent signaling in the projection neurons of the SCDH during the maintenance of PDN.
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Affiliation(s)
- Jacqueline R Dauch
- Department of Neurology, University of Michigan Medical Center, Ann Arbor, MI 48109-2200, USA
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Luo Q, Liu W, Chen J, Wang M, Zeng W, Chen Z, Cheng A. Nerve growth factor and inducible nitric oxide synthase expression in the mesencephalon and diencephalon, as well as visual- and auditory-related nervous tissues, in a macaque model of type 2 diabetes. Neural Regen Res 2012; 7:302-7. [PMID: 25806073 PMCID: PMC4353104 DOI: 10.3969/j.issn.1673-5374.2012.04.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2011] [Accepted: 12/22/2011] [Indexed: 11/18/2022] Open
Abstract
The present study detected distribution and expression of nerve growth factor and inducible nitric oxide synthase in the mesencephalon and diencephalon, as well as visual- and auditory-related nervous tissues, in a macaque model of type 2 diabetes using immunohistochemistry. Results showed that nerve growth factor expression decreased, but inducible nitric oxide synthase expression increased, in the mesencephalon and diencephalon, as well as visual- and auditory- related nervous tissues. These results suggested that nerve growth factor and inducible nitric oxide synthase play an important role in regulating the development of diabetic visual- and auditory-related diseases.
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Affiliation(s)
- Qihui Luo
- College of Veterinary Medicine, Sichuan Agricultural University/Key Laboratory of Animal Disease and Human Health of Sichuan Province, Ya’an 625014, Sichuan Province, China
- Experimental Animal Engineering Center, Sichuan Agricultural University/Provenance Source De pot of Macaque for National Experiment, Ya’an 625014, Sichuan Province, China
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, Sichuan Province, China
| | - Wentao Liu
- College of Veterinary Medicine, Sichuan Agricultural University/Key Laboratory of Animal Disease and Human Health of Sichuan Province, Ya’an 625014, Sichuan Province, China
- Experimental Animal Engineering Center, Sichuan Agricultural University/Provenance Source De pot of Macaque for National Experiment, Ya’an 625014, Sichuan Province, China
| | - Jingyao Chen
- College of Veterinary Medicine, Sichuan Agricultural University/Key Laboratory of Animal Disease and Human Health of Sichuan Province, Ya’an 625014, Sichuan Province, China
- Experimental Animal Engineering Center, Sichuan Agricultural University/Provenance Source De pot of Macaque for National Experiment, Ya’an 625014, Sichuan Province, China
| | - Mingshu Wang
- College of Veterinary Medicine, Sichuan Agricultural University/Key Laboratory of Animal Disease and Human Health of Sichuan Province, Ya’an 625014, Sichuan Province, China
- Experimental Animal Engineering Center, Sichuan Agricultural University/Provenance Source De pot of Macaque for National Experiment, Ya’an 625014, Sichuan Province, China
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, Sichuan Province, China
| | - Wen Zeng
- Experimental Animal Engineering Center, Sichuan Agricultural University/Provenance Source De pot of Macaque for National Experiment, Ya’an 625014, Sichuan Province, China
- Sinopharm Center for Safety Evaluation and Research, Chengdu 610051, Sichuan Province, China
| | - Zhengli Chen
- College of Veterinary Medicine, Sichuan Agricultural University/Key Laboratory of Animal Disease and Human Health of Sichuan Province, Ya’an 625014, Sichuan Province, China
- Experimental Animal Engineering Center, Sichuan Agricultural University/Provenance Source De pot of Macaque for National Experiment, Ya’an 625014, Sichuan Province, China
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, Sichuan Province, China
| | - Anchun Cheng
- College of Veterinary Medicine, Sichuan Agricultural University/Key Laboratory of Animal Disease and Human Health of Sichuan Province, Ya’an 625014, Sichuan Province, China
- Experimental Animal Engineering Center, Sichuan Agricultural University/Provenance Source De pot of Macaque for National Experiment, Ya’an 625014, Sichuan Province, China
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, Sichuan Province, China
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Stavniichuk R, Shevalye H, Hirooka H, Nadler JL, Obrosova IG. Interplay of sorbitol pathway of glucose metabolism, 12/15-lipoxygenase, and mitogen-activated protein kinases in the pathogenesis of diabetic peripheral neuropathy. Biochem Pharmacol 2012; 83:932-40. [PMID: 22285226 DOI: 10.1016/j.bcp.2012.01.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 01/11/2012] [Accepted: 01/12/2012] [Indexed: 01/15/2023]
Abstract
The interactions among multiple pathogenetic mechanisms of diabetic peripheral neuropathy largely remain unexplored. Increased activity of aldose reductase, the first enzyme of the sorbitol pathway, leads to accumulation of cytosolic Ca²⁺, essentially required for 12/15-lipoxygenase activation. The latter, in turn, causes oxidative-nitrosative stress, an important trigger of mitogen activated protein kinase (MAPK) phosphorylation. This study therefore evaluated the interplay of aldose reductase, 12/15-lipoxygenase, and MAPKs in diabetic peripheral neuropathy. In experiment 1, male control and streptozotocin-diabetic mice were maintained with or without the aldose reductase inhibitor fidarestat, 16 mg kg⁻¹ d⁻¹, for 12 weeks. In experiment 2, male control and streptozotocin-diabetic wild-type (C57Bl6/J) and 12/15-lipoxygenase-deficient mice were used. Fidarestat treatment did not affect diabetes-induced increase in glucose concentrations, but normalized sorbitol and fructose concentrations (enzymatic spectrofluorometric assays) as well as 12(S)-hydroxyeicosatetraenoic concentration (ELISA), a measure of 12/15-lipoxygenase activity, in the sciatic nerve and spinal cord. 12/15-lipoxygenase expression in these two tissues (Western blot analysis) as well as dorsal root ganglia (immunohistochemistry) was similarly elevated in untreated and fidarestat-treated diabetic mice. 12/15-Lipoxygenase gene deficiency prevented diabetes-associated p38 MAPK and ERK, but not SAPK/JNK, activation in the sciatic nerve (Western blot analysis) and all three MAPK activation in the dorsal root ganglia (immunohistochemistry). In contrast, spinal cord p38 MAPK, ERK, and SAPK/JNK were similarly activated in diabetic wild-type and 12/15-lipoxygenase⁻/⁻ mice. These findings identify the nature and tissue specificity of interactions among three major mechanisms of diabetic peripheral neuropathy, and suggest that combination treatments, rather than monotherapies, can sometimes be an optimal choice for its management.
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Affiliation(s)
- Roman Stavniichuk
- Pennington Biomedical Research Center, Louisiana State University System, 6400 Perkins Road, Baton Rouge, LA 70808, USA
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Yamakawa I, Kojima H, Terashima T, Katagi M, Oi J, Urabe H, Sanada M, Kawai H, Chan L, Yasuda H, Maegawa H, Kimura H. Inactivation of TNF-α ameliorates diabetic neuropathy in mice. Am J Physiol Endocrinol Metab 2011; 301:E844-52. [PMID: 21810933 PMCID: PMC3213998 DOI: 10.1152/ajpendo.00029.2011] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Tumor necrosis factor (TNF)-α is a potent proinflammatory cytokine involved in the pathogenesis of diabetic neuropathy. We inactivated TNF-α to determine if it is a valid therapeutic target for the treatment of diabetic neuropathy. We effected the inactivation in diabetic neuropathy using two approaches: by genetic inactivation of TNF-α (TNF-α(-/-) mice) or by neutralization of TNF-α protein using the monoclonal antibody infliximab. We induced diabetes using streptozotocin in wild-type and TNF-α(-/-) mice. We measured serum TNF-α concentration and the level of TNF-α mRNA in the dorsal root ganglion (DRG) and evaluated nerve function by a combination of motor (MNCV) and sensory (SNCV) nerve conduction velocities and tail flick test, as well as cytological analysis of intraepidermal nerve fiber density (IENFD) and immunostaining of DRG for NF-κB p65 serine-276 phosphorylated and cleaved caspase-3. Compared with nondiabetic mice, TNF-α(+/+) diabetic mice displayed significant impairments of MNCV, SNCV, tail flick test, and IENFD as well as increased expression of NF-κB p65 and cleaved caspase-3 in their DRG. In contrast, although nondiabetic TNF-α(-/-) mice showed mild abnormalities of IENFD under basal conditions, diabetic TNF-α(-/-) mice showed no evidence of abnormal nerve function tests compared with nondiabetic mice. A single injection of infliximab in diabetic TNF-α(+/+) mice led to suppression of the increased serum TNF-α and amelioration of the electrophysiological and biochemical deficits for at least 4 wk. Moreover, the increased TNF-α mRNA expression in diabetic DRG was also attenuated by infliximab, suggesting infliximab's effects may involve the local suppression of TNF-α. Infliximab, an agent currently in clinical use, is effective in targeting TNF-α action and expression and amelioration of diabetic neuropathy in mice.
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MESH Headings
- Animals
- Anti-Inflammatory Agents/pharmacology
- Anti-Inflammatory Agents/therapeutic use
- Antibodies, Monoclonal/pharmacology
- Antibodies, Monoclonal/therapeutic use
- Diabetes Mellitus, Experimental/chemically induced
- Diabetes Mellitus, Experimental/complications
- Diabetes Mellitus, Experimental/genetics
- Diabetes Mellitus, Experimental/pathology
- Diabetic Neuropathies/drug therapy
- Diabetic Neuropathies/genetics
- Diabetic Neuropathies/metabolism
- Diabetic Neuropathies/pathology
- Drug Evaluation, Preclinical
- Ganglia, Spinal/metabolism
- Ganglia, Spinal/pathology
- Gene Expression Regulation/drug effects
- Gene Silencing/physiology
- Infliximab
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Molecular Targeted Therapy
- Streptozocin
- Transcription Factor RelA/metabolism
- Tumor Necrosis Factor-alpha/antagonists & inhibitors
- Tumor Necrosis Factor-alpha/genetics
- Tumor Necrosis Factor-alpha/metabolism
- Tumor Necrosis Factor-alpha/physiology
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Affiliation(s)
- Isamu Yamakawa
- Department of Molecular Genetics in Medicine, Shiga University of Medical Science, Otsu, Shiga, Japan
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Cheng HT, Dauch JR, Hayes JM, Yanik BM, Feldman EL. Nerve growth factor/p38 signaling increases intraepidermal nerve fiber densities in painful neuropathy of type 2 diabetes. Neurobiol Dis 2011; 45:280-7. [PMID: 21872660 DOI: 10.1016/j.nbd.2011.08.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Revised: 07/26/2011] [Accepted: 08/03/2011] [Indexed: 10/17/2022] Open
Abstract
Painful diabetic neuropathy (PDN) is a common, yet devastating complication of type 2 diabetes. At this time, there is no objective test for diagnosing PDN. In the current study, we measured the peptidergic intraepidermal nerve fiber densities (IENFD) from hind paws of the db/db mouse, an animal model for type 2 diabetes, during the period of mechanical allodynia from 6 to 12 weeks of age. Intraepidermal nerve fibers (IENF) of the hind footpads were identified by protein gene product (PGP) 9.5 immunohistochemistry. The peptidergic IENF were determined by double immunofluorescence using anti-PGP9.5 and antibodies against tropomyosin-receptor-kinase (Trk) A. We observed a significant increase in PGP9.5-positive IENFD at 8 and 10 weeks of age. Similarly, Trk A-positive peptidergic IENF, which also express substance P and calcitonin gene related peptide in db/db mice, were observed to be elevated from 1.5 to 2 fold over controls. This upregulation ended at 16 weeks of age, in accordance with the reduction of mechanical allodynia. Anti-NGF treatment significantly inhibited the upregulation of peptidergic IENFD during the period of mechanical allodynia, suggesting that increased neurotrophism may mediate this phenomenon. In addition, SB203580, an inhibitor of p38, blocked the increase in peptidergic IENFD in db/db mice. The current results suggest that peptidergic IENFD could be a potential diagnostic indicator for PDN in type 2 diabetes. Furthermore, the inhibition of NGF-p38 signaling could be a potential therapeutic strategy for treating this painful condition.
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Affiliation(s)
- Hsinlin T Cheng
- Department of Neurology, University of Michigan Medical Center, Ann Arbor, Michigan 48109, USA.
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Liao YH, Zhang GH, Jia D, Wang P, Qian NS, He F, Zeng XT, He Y, Yang YL, Cao DY, Zhang Y, Wang DS, Tao KS, Gao CJ, Dou KF. Spinal astrocytic activation contributes to mechanical allodynia in a mouse model of type 2 diabetes. Brain Res 2010; 1368:324-35. [PMID: 20971097 DOI: 10.1016/j.brainres.2010.10.044] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 10/10/2010] [Accepted: 10/14/2010] [Indexed: 12/11/2022]
Abstract
Diabetic neuropathic pain (DNP) plays a major role in decreased life quality of type 2 diabetes patients, however, the molecular mechanisms underlying DNP remain unclear. Emerging research implicates the participation of spinal glial cells in some neuropathic pain models. However, it remains unknown whether spinal glial cells are activated under type 2 diabetic conditions and whether they contribute to diabetes-induced neuropathic pain. In the present study, using a db/db type 2 diabetes mouse model that displayed obvious mechanical allodynia, we found that spinal astrocyte but not microglia was dramatically activated. The mechanical allodynia was significantly attenuated by intrathecally administrated l-α-aminoadipate (astrocytic specific inhibitor) whereas minocycline (microglial specific inhibitor) did not have any effect on mechanical allodynia, which indicated that spinal astrocytic activation contributed to allodynia in db/db mice. Further study aimed to identify the detailed mechanism of astrocyte-induced allodynia in db/db mice. Results showed that spinal activated astrocytes dramatically increased interleukin (IL)-1β expression which may induce N-methyl-D-aspartic acid receptor (NMDAR) phosphorylation in spinal dorsal horn neurons to enhance pain transmission. Together, these results suggest that spinal activated astrocytes may be a crucial component of mechanical allodynia in type 2 diabetes and "Astrocyte-IL-1β-NMDAR-Neuron" pathway may be the detailed mechanism of astrocyte-induced allodynia. Thus, inhibiting astrocytic activation in the spinal dorsal horn may represent a novel therapeutic strategy for treating DNP.
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Affiliation(s)
- Yong-Hui Liao
- Department of Hepatobiliary Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, PR China
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