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Schicht M, Farger J, Wedel S, Sisignano M, Scholich K, Geisslinger G, Perumal N, Grus FH, Singh S, Sahin A, Paulsen F, Lütjen-Drecoll E. Ocular surface changes in mice with streptozotocin-induced diabetes and diabetic polyneuropathy. Ocul Surf 2024; 31:43-55. [PMID: 38141818 DOI: 10.1016/j.jtos.2023.12.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Revised: 12/13/2023] [Accepted: 12/20/2023] [Indexed: 12/25/2023]
Abstract
PURPOSE Diabetes mellitus (DM) is a leading risk factor for corneal neuropathy and dry eye disease (DED). Another common consequence of DM is diabetic peripheral polyneuropathy (DPN). Both complications affect around 50 % of the DM patients but the relationship between DM, DED and DPN remains unclear. METHODS In this study, we examined mice with early onset of DM and PN after streptozotocin (STZ)-induced diabetes (DPN). We compared the early morphological changes of the sciatic nerve, dorsal root and trigeminal ganglia with the changes in the ocular surface, including tear proteomic and we also investigated respective changes in the gene expressions and morphological alterations in the eye tissues involved in tear production. RESULTS The lacrimal gland, conjunctival goblet cells and cornea showed morphological changes along with alterations in tear proteins without any obvious signs of ocular surface inflammation. The gene expression for respectively altered tear proteins i.e., of Clusterin in cornea, Car6, Adh3a1, and Eef1a1 in eyelids, and Pigr in the lacrimal gland also showed significant changes compared to control mice. In the trigeminal ganglia like in the dorsal root ganglia neuronal cells showed swollen mitochondria and, in the latter, there was a significant increase of NADPH oxidases and MMP9 suggestive of oxidative and neuronal stress. In the dorsal root ganglia and the sciatic nerve, there was an upregulation of a number of pro-inflammatory cytokines and pain-mediating chemokines. CONCLUSION The early ocular changes in DM Mice only affect the lacrimal gland. Which, is reflected in the tear film composition of DPN mice. Due to the high protein concentration in tear fluid in humans, proteomic analysis in addition to noninvasive investigation of goblet cells and cornea can serve as a tools for the early diagnosis of DPN, DED in clinical practice. Early treatment could delay or even prevent the ocular complications of DM such as DED and PN.
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Affiliation(s)
- Martin Schicht
- Institute of Functional and Clinical Anatomy, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany.
| | - Jessica Farger
- Institute of Functional and Clinical Anatomy, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Saskia Wedel
- Institute of Clinical Pharmacology, Goethe University, Frankfurt am Main, Germany
| | - Marco Sisignano
- Institute of Clinical Pharmacology, Goethe University, Frankfurt am Main, Germany; Fraunhofer Institute for Translational Medicine and Pharmacology (ITMP), Frankfurt am Main, Department of Experimental and Translational Ophthalmology, Germany
| | - Klaus Scholich
- Institute of Clinical Pharmacology, Goethe University, Frankfurt am Main, Germany; Fraunhofer Institute for Translational Medicine and Pharmacology (ITMP), Frankfurt am Main, Department of Experimental and Translational Ophthalmology, Germany
| | - Gerd Geisslinger
- Institute of Clinical Pharmacology, Goethe University, Frankfurt am Main, Germany; Fraunhofer Institute for Translational Medicine and Pharmacology (ITMP), Frankfurt am Main, Department of Experimental and Translational Ophthalmology, Germany
| | - Natarajan Perumal
- Experimental and Translational Ophthalmology, Department of Ophthalmology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Franz H Grus
- Experimental and Translational Ophthalmology, Department of Ophthalmology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Swati Singh
- Institute of Functional and Clinical Anatomy, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Afsun Sahin
- Department of Ophthalmology, Koc University Medical School, Istanbul, Turkey
| | - Friedrich Paulsen
- Institute of Functional and Clinical Anatomy, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Elke Lütjen-Drecoll
- Institute of Functional and Clinical Anatomy, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
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Hu X, Buhl CS, Sjogaard MB, Schousboe K, Mizrak HI, Kufaishi H, Jensen TS, Hansen CS, Yderstræde KB, Zhang MD, Ernfors P, Nyengaard JR, Karlsson P. Structural changes in Schwann cells and nerve fibres in type 1 diabetes: relationship with diabetic polyneuropathy. Diabetologia 2023; 66:2332-2345. [PMID: 37728731 PMCID: PMC10627903 DOI: 10.1007/s00125-023-06009-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 08/01/2023] [Indexed: 09/21/2023]
Abstract
AIMS/HYPOTHESIS Our aim was to investigate structural changes of cutaneous Schwann cells (SCs), including nociceptive Schwann cells (nSCs) and axons, in individuals with diabetic polyneuropathy. We also aimed to investigate the relationship between these changes and peripheral neuropathic symptoms in type 1 diabetes. METHODS Skin biopsies (3 mm) taken from carefully phenotyped participants with type 1 diabetes without polyneuropathy (T1D, n=25), type 1 diabetes with painless diabetic polyneuropathy (T1DPN, n=30) and type 1 diabetes with painful diabetic polyneuropathy (P-T1DPN, n=27), and from healthy control individuals (n=25) were immunostained with relevant antibodies to visualise SCs and nerve fibres. Stereological methods were used to quantify the expression of cutaneous SCs and nerve fibres. RESULTS There was a difference in the number density of nSCs not abutting to nerve fibres between the groups (p=0.004) but not in the number density of nSCs abutting to nerve fibres, nor in solitary or total subepidermal SC soma number density. The overall dermal SC expression (measured by dermal SC area fraction and subepidermal SC process density) and peripheral nerve fibre expression (measured by intraepidermal nerve fibre density, dermal nerve fibre area fraction and subepidermal nerve fibre density) differed between the groups (all p<0.05): significant differences were seen in participants with T1DPN and P-T1DPN compared with those without diabetic polyneuropathy (healthy control and T1D groups) (all p<0.05). No difference was found between participants in the T1DPN and P-T1DPN group, nor between participants in the T1D and healthy control group (all p>0.05). Correlational analysis showed that cutaneous SC processes and nerve fibres were highly associated, and they were weakly negatively correlated with different neuropathy measures. CONCLUSIONS/INTERPRETATION Cutaneous SC processes and nerves, but not SC soma, are degenerated and interdependent in individuals with diabetic polyneuropathy. However, an increase in structurally damaged nSCs was seen in individuals with diabetic polyneuropathy. Furthermore, dermal SC processes and nerve fibres correlate weakly with clinical measures of neuropathy and may play a partial role in the pathophysiology of diabetic polyneuropathy in type 1 diabetes.
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Affiliation(s)
- Xiaoli Hu
- Core Center for Molecular Morphology, Section for Stereology and Microscopy, Aarhus University, Aarhus, Denmark
| | | | - Marie Balle Sjogaard
- Core Center for Molecular Morphology, Section for Stereology and Microscopy, Aarhus University, Aarhus, Denmark
- Danish Pain Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Karoline Schousboe
- Steno Diabetes Center Odense, Odense University Hospital, Odense, Denmark
| | | | | | - Troels Staehelin Jensen
- Danish Pain Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- Department of Neurology, Aarhus University Hospital, Aarhus, Denmark
| | | | | | - Ming-Dong Zhang
- Department of Medical Biochemistry and Biophysics, Division of Molecular Neurobiology, Karolinska Institutet, Stockholm, Sweden
| | - Patrik Ernfors
- Department of Medical Biochemistry and Biophysics, Division of Molecular Neurobiology, Karolinska Institutet, Stockholm, Sweden
| | - Jens Randel Nyengaard
- Core Center for Molecular Morphology, Section for Stereology and Microscopy, Aarhus University, Aarhus, Denmark
- Department of Pathology, Aarhus University Hospital, Aarhus, Denmark
| | - Pall Karlsson
- Core Center for Molecular Morphology, Section for Stereology and Microscopy, Aarhus University, Aarhus, Denmark.
- Steno Diabetes Center Aarhus, Aarhus University Hospital, Aarhus, Denmark.
- Danish Pain Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
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Zhu GC, Chen YW, Tsai KL, Wang JJ, Hung CH, Schmid AB. Swimming exercise attenuates mechanical hypersensitivity and mitigates peripheral nerve degeneration in rats with painful diabetic neuropathy (PDN). Neurosci Lett 2023; 812:137406. [PMID: 37480979 DOI: 10.1016/j.neulet.2023.137406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 07/17/2023] [Accepted: 07/19/2023] [Indexed: 07/24/2023]
Abstract
BACKGROUND This study aimed to assess the effectiveness of swimming exercise in alleviating mechanical hypersensitivity and peripheral nerve degeneration associated with a pre-clinical model of painful diabetic neuropathy (PDN). METHODS This study is a pre-clinical study conducted using the streptozocin (STZ)-induced PDN rat model. Rats were randomly allocated to three groups: a vehicle group of non-diabetic rats (Vehicle, n = 9), a group of rats with PDN (PDN, n = 8), and a group of rats with PDN that performed a swimming exercise program (PDN-SW, n = 10). The swimming exercise program included daily 30-minute swimming exercise, 5 days per week for 4 weeks. Von Frey testing was used to monitor hindpaw mechanical sensitivity over 4 weeks. Assessment of cutaneous peripheral nerve fiber integrity was performed after the 4-week study period via immunohistochemistry for protein gene product 9.5-positive (PGP9.5+) intra-epidermal nerve fiber density (IENFD) in hind-paw skin biopsies by a blinded investigator. RESULTS The results showed that swimming exercise mitigated but did not fully reverse mechanical hypersensitivity in rats with PDN. Immunohistochemical testing revealed that the rats in the PDN-SW group retained higher PGP9.5+ IENFD compared to the PDN group but did not reach normal levels of the Vehicle group. CONCLUSIONS The results of this study indicate that swimming exercise can mitigate mechanical hypersensitivity and degeneration of peripheral nerve fibers in rats with experimental PDN.
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Affiliation(s)
- Guan-Cheng Zhu
- Department of Physical Therapy, National Cheng Kung University, Tainan, Taiwan, ROC
| | - Yu-Wen Chen
- Department of Physical Therapy, China Medical University, Taichung, Taiwan, ROC
| | - Kun-Ling Tsai
- Department of Physical Therapy, National Cheng Kung University, Tainan, Taiwan, ROC
| | - Jhi-Joung Wang
- Department of Medical Research, Chi-Mei Medical Center, Tainan, Taiwan, ROC
| | - Ching-Hsia Hung
- Department of Physical Therapy, National Cheng Kung University, Tainan, Taiwan, ROC.
| | - Annina B Schmid
- Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, UK
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Zhu GC, Chen YW, Tsai KL, Wang JJ, Hung CH, Schmid AB. Effects of Neural Mobilization on Sensory Dysfunction and Peripheral Nerve Degeneration in Rats With Painful Diabetic Neuropathy. Phys Ther 2022; 102:6652922. [PMID: 35913760 PMCID: PMC7613682 DOI: 10.1093/ptj/pzac104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 03/16/2022] [Accepted: 06/07/2022] [Indexed: 11/13/2022]
Abstract
OBJECTIVE This study aims to evaluate the effectiveness of neural mobilization (NM) in the management of sensory dysfunction and nerve degeneration related to experimental painful diabetic neuropathy (PDN). METHODS This is a pre-clinical animal study performed in the streptozocin-induced diabetic rat model. Three groups were included: a treatment group of rats with PDN receiving NM under anesthesia (PDN-NM, n = 10), a sham treatment group of rats with PDN that received only anesthesia (PDN-Sham, n = 9), and a vehicle control group with nondiabetic animals (Vehicle, n = 10). Rats in the PDN-NM and PDN-Sham groups received 1 treatment session on days 10, 12, and 14 after streptozocin injection, with a 48-hour rest period between sessions. Behavioral tests were performed using von Frey and Plantar tests. Evaluation for peripheral nerve degeneration was performed through measuring protein gene product 9.5-positive intra-epidermal nerve fiber density in hind-paw skin biopsies. All measurements were performed by a blinded investigator. RESULTS The behavioral tests showed that a single NM session could reduce hyperalgesia, which was maintained for 48 hours. The second treatment session further improved this treatment effect, and the third session maintained it. These results suggest that it requires multiple treatment sessions to produce and maintain hypoalgesic effects. Skin biopsy analysis showed that the protein gene product 9.5-positive intra-epidermal nerve fiber density was higher on the experimental side of the PDN-NM group compared with the PDN-Sham group, suggesting NM may mitigate the degeneration of peripheral nerves. CONCLUSION This study demonstrated that NM may be an effective method to manage experimentally induced PDN, potentially through mitigation of nerve degeneration. Further studies are needed to develop standardized protocols for clinical use. IMPACT These findings provide neurophysiological evidence for the use of NM in PDN and can form the basis for the development of physical therapy-based programs in clinics.
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Affiliation(s)
- Guan-Cheng Zhu
- Department of Physical Therapy, National Cheng Kung University, Tainan, Taiwan (R.O.C.)
| | - Yu-Wen Chen
- Department of Physical Therapy, China Medical University, Taichung, Taiwan (R.O.C.)
| | - Kun-Ling Tsai
- Department of Physical Therapy, National Cheng Kung University, Tainan, Taiwan (R.O.C.)
| | - Jhi-Joung Wang
- Department of Medical Research, Chi-Mei Medical Center, Tainan, Taiwan (R.O.C.)
| | - Ching-Hsia Hung
- Department of Physical Therapy, National Cheng Kung University, Tainan, Taiwan (R.O.C.)
| | - Annina B. Schmid
- Nuffield Department of Clinical Neuroscience, University of Oxford, Level 6, West Wing, John Radcliffe Hospital, Oxford OX3 9DU, U.K
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Albrecht PJ, Houk G, Ruggiero E, Dockum M, Czerwinski M, Betts J, Wymer JP, Argoff CE, Rice FL. Keratinocyte Biomarkers Distinguish Painful Diabetic Peripheral Neuropathy Patients and Correlate With Topical Lidocaine Responsiveness. FRONTIERS IN PAIN RESEARCH 2021; 2:790524. [PMID: 35295428 PMCID: PMC8915676 DOI: 10.3389/fpain.2021.790524] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 11/03/2021] [Indexed: 01/11/2023] Open
Abstract
This study investigated quantifiable measures of cutaneous innervation and algesic keratinocyte biomarkers to determine correlations with clinical measures of patient pain perception, with the intent to better discriminate between diabetic patients with painful diabetic peripheral neuropathy (PDPN) compared to patients with low-pain diabetic peripheral neuropathy (lpDPN) or healthy control subjects. A secondary objective was to determine if topical treatment with a 5% lidocaine patch resulted in correlative changes among the quantifiable biomarkers and clinical measures of pain perception, indicative of potential PDPN pain relief. This open-label proof-of-principle clinical research study consisted of a pre-treatment skin biopsy, a 4-week topical 5% lidocaine patch treatment regimen for all patients and controls, and a post-treatment skin biopsy. Clinical measures of pain and functional interference were used to monitor patient symptoms and response for correlation with quantitative skin biopsy biomarkers of innervation (PGP9.5 and CGRP), and epidermal keratinocyte biomarkers (Nav1.6, Nav1.7, CGRP). Importantly, comparable significant losses of epidermal neural innervation (intraepidermal nerve fibers; IENF) and dermal innervation were observed among PDPN and lpDPN patients compared with control subjects, indicating that innervation loss alone may not be the driver of pain in diabetic neuropathy. In pre-treatment biopsies, keratinocyte Nav1.6, Nav1.7, and CGRP immunolabeling were all significantly increased among PDPN patients compared with control subjects. Importantly, no keratinocyte biomarkers were significantly increased among the lpDPN group compared with control. In post-treatment biopsies, the keratinocyte Nav1.6, Nav1.7, and CGRP immunolabeling intensities were no longer different between control, lpDPN, or PDPN cohorts, indicating that lidocaine treatment modified the PDPN-related keratinocyte increases. Analysis of the PDPN responder population demonstrated that increased pretreatment keratinocyte biomarker immunolabeling for Nav1.6, Nav1.7, and CGRP correlated with positive outcomes to topical lidocaine treatment. Epidermal keratinocytes modulate the signaling of IENF, and several analgesic and algesic signaling systems have been identified. These results further implicate epidermal signaling mechanisms as modulators of neuropathic pain conditions, highlight a novel potential mode of action for topical treatments, and demonstrate the utility of comprehensive skin biopsy evaluation to identify novel biomarkers in clinical pain studies.
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Affiliation(s)
- Phillip J. Albrecht
- Neuroscience and Pain Research Group, Integrated Tissue Dynamics, LLC, Rensselaer, NY, United States
- Division of Health Sciences, University at Albany, Albany, NY, United States
- *Correspondence: Phillip J. Albrecht
| | - George Houk
- Neuroscience and Pain Research Group, Integrated Tissue Dynamics, LLC, Rensselaer, NY, United States
| | - Elizabeth Ruggiero
- Neuroscience and Pain Research Group, Integrated Tissue Dynamics, LLC, Rensselaer, NY, United States
| | - Marilyn Dockum
- Neuroscience and Pain Research Group, Integrated Tissue Dynamics, LLC, Rensselaer, NY, United States
| | | | - Joseph Betts
- Neuroscience and Pain Research Group, Integrated Tissue Dynamics, LLC, Rensselaer, NY, United States
| | - James P. Wymer
- Department of Neurology, University of Florida College of Medicine, Gainesville, FL, United States
| | - Charles E. Argoff
- Department of Neurology, Albany Medical Center, Albany, NY, United States
| | - Frank L. Rice
- Neuroscience and Pain Research Group, Integrated Tissue Dynamics, LLC, Rensselaer, NY, United States
- Division of Health Sciences, University at Albany, Albany, NY, United States
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Early Detection of Diabetic Peripheral Neuropathy: A Focus on Small Nerve Fibres. Diagnostics (Basel) 2021; 11:diagnostics11020165. [PMID: 33498918 PMCID: PMC7911433 DOI: 10.3390/diagnostics11020165] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 01/14/2021] [Accepted: 01/20/2021] [Indexed: 02/07/2023] Open
Abstract
Diabetic peripheral neuropathy (DPN) is the most common complication of both type 1 and 2 diabetes. As a result, neuropathic pain, diabetic foot ulcers and lower-limb amputations impact drastically on quality of life, contributing to the individual, societal, financial and healthcare burden of diabetes. DPN is diagnosed at a late, often pre-ulcerative stage due to a lack of early systematic screening and the endorsement of monofilament testing which identifies advanced neuropathy only. Compared to the success of the diabetic eye and kidney screening programmes there is clearly an unmet need for an objective reliable biomarker for the detection of early DPN. This article critically appraises research and clinical methods for the diagnosis or screening of early DPN. In brief, functional measures are subjective and are difficult to implement due to technical complexity. Moreover, skin biopsy is invasive, expensive and lacks diagnostic laboratory capacity. Indeed, point-of-care nerve conduction tests are convenient and easy to implement however questions are raised regarding their suitability for use in screening due to the lack of small nerve fibre evaluation. Corneal confocal microscopy (CCM) is a rapid, non-invasive, and reproducible technique to quantify small nerve fibre damage and repair which can be conducted alongside retinopathy screening. CCM identifies early sub-clinical DPN, predicts the development and allows staging of DPN severity. Automated quantification of CCM with AI has enabled enhanced unbiased quantification of small nerve fibres and potentially early diagnosis of DPN. Improved screening tools will prevent and reduce the burden of foot ulceration and amputations with the primary aim of reducing the prevalence of this common microvascular complication.
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Alam U, Petropoulos IN, Ponirakis G, Ferdousi M, Asghar O, Jeziorska M, Marshall A, Boulton AJM, Efron N, Malik RA. Vitamin D deficiency is associated with painful diabetic neuropathy. Diabetes Metab Res Rev 2021; 37:e3361. [PMID: 32506740 DOI: 10.1002/dmrr.3361] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 05/12/2020] [Accepted: 05/18/2020] [Indexed: 11/11/2022]
Abstract
BACKGROUND The aetiology of painful diabetic neuropathy is unclear. We have evaluated vitamin D levels in diabetic patients with and without painful neuropathy. METHODS Forty-three patients with type 1 diabetes and painless (DPN) (n = 20) or painful (PDN) (n = 23) neuropathy and 14 non-diabetic healthy control subjects (C) underwent assessment of neurologic deficits, quantitative sensory testing (QST), electrophysiology, skin biopsy, corneal confocal microscopy (CCM) and measurement of serum 25(OH)D. RESULTS There were no significant differences for age, BMI, HbA1c , lipids, neurological deficits, QST, electrophysiology, intra-epidermal nerve fibre density (IENFD) and corneal nerve morphology between patients with DPN and PDN. Both positive (hyperalgesia and allodynia) and negative symptoms (paraesthesia and numbness) of diabetic neuropathy were greater in PDN compared with DPN (P = .009 and P = .02, respectively). Serum 25(OH)D levels were significantly lower in PDN (24.0 ± 14.1 ng/mL) compared with DPN (34.6 ± 15.0 ng/mL, P = .01) and controls (34.1 ± 8.6 ng/mL, P = .03). The odds ratio in favour of painful diabetic neuropathy was 9.8 [P = .003 (95% CI, 2.2-76.4)] for vitamin D deficiency (<20 ng/mL) and 4.4 [P = .03 (95% CI, 1.1-19.8)] for vitamin D insufficiency (<30 ng/mL). CONCLUSIONS This study suggests that vitamin D deficiency and insufficiency are associated with painful diabetic neuropathy.
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Affiliation(s)
- Uazman Alam
- Department of Cardiovascular & Metabolic Medicine and the Pain Research Institute, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
- Department of Diabetes, Endocrinology & Gastroenterology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | | | - Georgios Ponirakis
- Weill Cornell Medicine-Qatar, Research Division, Qatar Foundation, Doha, Qatar
| | - Maryam Ferdousi
- Institute of Cardiovascular Sciences, Cardiac Centre, Faculty of Medical and Human Sciences, University of Manchester and NIHR Clinical Research Facility, Manchester, UK
| | - Omar Asghar
- Institute of Cardiovascular Sciences, Cardiac Centre, Faculty of Medical and Human Sciences, University of Manchester and NIHR Clinical Research Facility, Manchester, UK
| | - Maria Jeziorska
- Institute of Cardiovascular Sciences, Cardiac Centre, Faculty of Medical and Human Sciences, University of Manchester and NIHR Clinical Research Facility, Manchester, UK
| | - Andrew Marshall
- Pain Research Institute, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
| | - Andrew J M Boulton
- Institute of Cardiovascular Sciences, Cardiac Centre, Faculty of Medical and Human Sciences, University of Manchester and NIHR Clinical Research Facility, Manchester, UK
| | - Nathan Efron
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
| | - Rayaz A Malik
- Weill Cornell Medicine-Qatar, Research Division, Qatar Foundation, Doha, Qatar
- Institute of Cardiovascular Sciences, Cardiac Centre, Faculty of Medical and Human Sciences, University of Manchester and NIHR Clinical Research Facility, Manchester, UK
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De Gregorio C, Contador D, Díaz D, Cárcamo C, Santapau D, Lobos-Gonzalez L, Acosta C, Campero M, Carpio D, Gabriele C, Gaspari M, Aliaga-Tobar V, Maracaja-Coutinho V, Ezquer M, Ezquer F. Human adipose-derived mesenchymal stem cell-conditioned medium ameliorates polyneuropathy and foot ulceration in diabetic BKS db/db mice. Stem Cell Res Ther 2020; 11:168. [PMID: 32357914 PMCID: PMC7195803 DOI: 10.1186/s13287-020-01680-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 03/31/2020] [Accepted: 04/15/2020] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Diabetic polyneuropathy (DPN) is the most common and early developing complication of diabetes mellitus, and the key contributor for foot ulcers development, with no specific therapies available. Different studies have shown that mesenchymal stem cell (MSC) administration is able to ameliorate DPN; however, limited cell survival and safety reasons hinder its transfer from bench to bedside. MSCs secrete a broad range of antioxidant, neuroprotective, angiogenic, and immunomodulatory factors (known as conditioned medium), which are all decreased in the peripheral nerves of diabetic patients. Furthermore, the abundance of these factors can be boosted in vitro by incubating MSCs with a preconditioning stimulus, enhancing their therapeutic efficacy. We hypothesize that systemic administration of conditioned medium derived from preconditioned MSCs could reverse DPN and prevent foot ulcer formation in a mouse model of type II diabetes mellitus. METHODS Diabetic BKS db/db mice were treated with systemic administration of conditioned medium derived from preconditioned human MSCs; conditioned medium derived from non-preconditioned MSCs or vehicle after behavioral signs of DPN was already present. Conditioned medium or vehicle administration was repeated every 2 weeks for a total of four administrations, and several functional and structural parameters characteristic of DPN were evaluated. Finally, a wound was made in the dorsal surface of both feet, and the kinetics of wound closure, re-epithelialization, angiogenesis, and cell proliferation were evaluated. RESULTS Our molecular, electrophysiological, and histological analysis demonstrated that the administration of conditioned medium derived from non-preconditioned MSCs or from preconditioned MSCs to diabetic BKS db/db mice strongly reverts the established DPN, improving thermal and mechanical sensitivity, restoring intraepidermal nerve fiber density, reducing neuron and Schwann cell apoptosis, improving angiogenesis, and reducing chronic inflammation of peripheral nerves. Furthermore, DPN reversion induced by conditioned medium administration enhances the wound healing process by accelerating wound closure, improving the re-epithelialization of the injured skin and increasing blood vessels in the wound bed in a skin injury model that mimics a foot ulcer. CONCLUSIONS Studies conducted indicate that MSC-conditioned medium administration could be a novel cell-free therapeutic approach to reverse the initial stages of DPN, avoiding the risk of lower limb amputation triggered by foot ulcer formation and accelerating the wound healing process in case it occurs.
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Affiliation(s)
- Cristian De Gregorio
- Center for Regenerative Medicine, School of Medicine Clínica Alemana-Universidad del Desarrollo, Av. Las Condes 12438, Lo Barnechea, Santiago, Chile
| | - David Contador
- Center for Regenerative Medicine, School of Medicine Clínica Alemana-Universidad del Desarrollo, Av. Las Condes 12438, Lo Barnechea, Santiago, Chile
| | - Diego Díaz
- Center for Regenerative Medicine, School of Medicine Clínica Alemana-Universidad del Desarrollo, Av. Las Condes 12438, Lo Barnechea, Santiago, Chile
| | - Constanza Cárcamo
- Center for Regenerative Medicine, School of Medicine Clínica Alemana-Universidad del Desarrollo, Av. Las Condes 12438, Lo Barnechea, Santiago, Chile
| | - Daniela Santapau
- Center for Regenerative Medicine, School of Medicine Clínica Alemana-Universidad del Desarrollo, Av. Las Condes 12438, Lo Barnechea, Santiago, Chile
| | - Lorena Lobos-Gonzalez
- Center for Regenerative Medicine, School of Medicine Clínica Alemana-Universidad del Desarrollo, Av. Las Condes 12438, Lo Barnechea, Santiago, Chile
| | - Cristian Acosta
- Institute of Histology and Embryology of Mendoza (IHEM-CONICET), School of Medicine, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Mario Campero
- Department of Neurology & Neurosurgery, Hospital José Joaquín Aguirre, Universidad de Chile, Santiago, Chile
| | - Daniel Carpio
- Institute of Anatomy, Histology and Pathology, Universidad Austral de Chile, Valdivia, Chile
| | - Caterina Gabriele
- Research Center for Advanced Biochemistry and Molecular Biology, Department of Experimental and Clinical Medicine, University of Catanzaro, Catanzaro, Italy
| | - Marco Gaspari
- Research Center for Advanced Biochemistry and Molecular Biology, Department of Experimental and Clinical Medicine, University of Catanzaro, Catanzaro, Italy
| | - Victor Aliaga-Tobar
- Advanced Center for Chronic Diseases-ACCDiS, Faculty of Chemical and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile
| | - Vinicius Maracaja-Coutinho
- Advanced Center for Chronic Diseases-ACCDiS, Faculty of Chemical and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile
| | - Marcelo Ezquer
- Center for Regenerative Medicine, School of Medicine Clínica Alemana-Universidad del Desarrollo, Av. Las Condes 12438, Lo Barnechea, Santiago, Chile
| | - Fernando Ezquer
- Center for Regenerative Medicine, School of Medicine Clínica Alemana-Universidad del Desarrollo, Av. Las Condes 12438, Lo Barnechea, Santiago, Chile.
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Abstract
PURPOSE OF REVIEW The goal of this review is to explore clinical associations between peripheral neuropathy and diabetic bone disease and to discuss how nerve dysfunction may contribute to dysregulation of bone metabolism, reduced bone quality, and fracture risk. RECENT FINDINGS Diabetic neuropathy can decrease peripheral sensation (sensory neuropathy), impair motor coordination (motor neuropathy), and increase postural hypotension (autonomic neuropathy). Together, this can impair overall balance and increase the risk for falls and fractures. In addition, the peripheral nervous system has the potential to regulate bone metabolism directly through the action of local neurotransmitters on bone cells and indirectly through neuroregulation of the skeletal vascular supply. This review critically evaluates existing evidence for diabetic peripheral neuropathy as a risk factor or direct actor on bone disease. In addition, we address therapeutic and experimental considerations to guide patient care and future research evaluating the emerging relationship between diabetic neuropathy and bone health.
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Affiliation(s)
- Alec T Beeve
- Department of Medicine, Division of Bone and Mineral Diseases, Washington University, 660 South Euclid Avenue, Saint Louis, MO, 63110, USA
- Department of Biomedical Engineering, Washington University, 6201 Forsyth Blvd, Saint Louis, MO, 63105, USA
| | - Jennifer M Brazill
- Department of Medicine, Division of Bone and Mineral Diseases, Washington University, 660 South Euclid Avenue, Saint Louis, MO, 63110, USA
| | - Erica L Scheller
- Department of Medicine, Division of Bone and Mineral Diseases, Washington University, 660 South Euclid Avenue, Saint Louis, MO, 63110, USA.
- Department of Biomedical Engineering, Washington University, 6201 Forsyth Blvd, Saint Louis, MO, 63105, USA.
- Department of Cell Biology and Physiology, Washington University, 660 South Euclid Avenue, Saint Louis, MO, 63110, USA.
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Structure–function relationships in peripheral nerve contributions to diabetic peripheral neuropathy. Pain 2019; 160 Suppl 1:S29-S36. [DOI: 10.1097/j.pain.0000000000001530] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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11
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Ismail CAN, Aziz CBA, Suppian R, Long I. Imbalanced oxidative stress and pro-inflammatory markers differentiate the development of diabetic neuropathy variants in streptozotocin-induced diabetic rats. J Diabetes Metab Disord 2018; 17:129-136. [PMID: 30918846 DOI: 10.1007/s40200-018-0350-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 08/07/2018] [Indexed: 12/30/2022]
Abstract
Purpose Diabetic neuropathy is a prolonged symptom of diabetes mellitus that affect a number of diabetes mellitus patients. So far, the variants of diabetic neuropathy, either painful (PDN) or non-painful (or painless, non-PDN) response have distinctive clinical entities. This study aims to determine the effects of oxidative stress parameters and pro-inflammatory factors at spinal cord level of streptozotocin-induced diabetic neuropathy rat model. Methods Thirty Sprague-Dawley rats were randomly assigned to control (non-diabetic), PDN and non-PDN groups (n = 10). The rats were induced with diabetes by streptozotocin injection (60 mg/kg). Tactile allodynia and thermal hyperalgesia were assessed on day 0, 14 (week 2) and 21 (week 3) in the rats. The rats were sacrificed and the spinal cord tissue was collected for the measurement of oxidative stress (malondialdehyde (MDA), superoxide dismutase (SOD) and catalase) and pro-inflammatory markers (interleukin-1β (IL-1β) and tumour necrosis factor-α (TNF-α)). Results PDN rats demonstrated a marked tactile allodynia with no thermal hyperalgesia whilst non-PDN rats exhibited a prominent hypo-responsiveness towards non-noxious stimuli and hypoalgesia towards thermal input. The MDA level and pro-inflammatory TNF-α was significantly increased in PDN rats whilst catalase was reduced in these rats. Meanwhile, non-PDN rats demonstrated reduced SOD enzyme activity and TNF-α level and increased MDA and catalase activity. Conclusion The changes in oxidative stress parameters and pro-inflammatory factors may contribute to the changes in behavioural responses in both PDN and non-PDN rats.
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Affiliation(s)
- Che Aishah Nazariah Ismail
- 1Physiology Department, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan Malaysia.,2School of Health Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan Malaysia
| | - Che Badariah Abd Aziz
- 1Physiology Department, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan Malaysia
| | - Rapeah Suppian
- 2School of Health Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan Malaysia
| | - Idris Long
- 2School of Health Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan Malaysia
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12
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Athie MCP, Vieira AS, Teixeira JM, dos Santos GG, Dias EV, Tambeli CH, Sartori CR, Parada CA. Transcriptome analysis of dorsal root ganglia's diabetic neuropathy reveals mechanisms involved in pain and regeneration. Life Sci 2018; 205:54-62. [DOI: 10.1016/j.lfs.2018.05.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 04/26/2018] [Accepted: 05/06/2018] [Indexed: 11/15/2022]
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13
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Noh SU, Lee WY, Kim WS, Lee YT, Yoon KJ. Expression of macrophage migration inhibitory factor in footpad skin lesions with diabetic neuropathy. Mol Pain 2018; 14:1744806918775482. [PMID: 29690804 PMCID: PMC5968664 DOI: 10.1177/1744806918775482] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Background Diabetic neuropathy originating in distal lower extremities is associated
with pain early in the disease course, overwhelming in the feet. However,
the pathogenesis of diabetic neuropathy remains unclear. Macrophage
migration inhibitory factor has been implicated in the onset of neuropathic
pain and the development of diabetes. Objective of this study was to observe
pain syndromes elicited in the footpad of diabetic neuropathy rat model and
to assess the contributory role of migration inhibitory factor in the
pathogenesis of diabetic neuropathy. Methods Diabetic neuropathy was made in Sprague Dawley rats by streptozotocin. Pain
threshold was evaluated using von Frey monofilaments for 24 weeks. On
comparable experiment time after streptozotocin injection, all footpads were
prepared for following procedures; glutathione assay, terminal
deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling
staining, immunohistochemistry staining, real-time reverse transcription
polymerase chain reaction, and Western blot. Additionally, human HaCaT skin
keratinocytes were treated with methylglyoxal, transfected with migration
inhibitory factor/control small interfering RNA, and prepared for real-time
reverse transcription polymerase chain reaction and Western blot. Results As compared to sham group, pain threshold was significantly reduced in
diabetic neuropathy group, and glutathione was decreased in footpad skin,
simultaneously, cell death was increased. Over-expression of migration
inhibitory factor, accompanied by low expression of glyoxalase-I and
intraepidermal nerve fibers, was shown on the footpad skin lesions of
diabetic neuropathy. But, there was no significance in expression of
neurotransmitters and inflammatory mediators such as transient receptor
potential vanilloid 1, mas-related G protein coupled receptor D, nuclear
factor kappa B, tumor necrosis factor-alpha, and interleukin-6 between
diabetic neuropathy group and sham group. Intriguingly, small interfering
RNA-transfected knockdown of the migration inhibitory factor gene in
methylglyoxal-treated skin keratinocytes increased expression of
glyoxalase-I and intraepidermal nerve fibers in comparison with control
small interfering RNA-transfected cells, which was decreased by induction of
methylglyoxal. Conclusions Our findings suggest that migration inhibitory factor can aggravate diabetic
neuropathy by suppressing glyoxalase-I and intraepidermal nerve fibers on
the footpad skin lesions and provoke pain. Taken together, migration
inhibitory factor might offer a pharmacological approach to alleviate pain
syndromes in diabetic neuropathy.
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Affiliation(s)
- Sun Up Noh
- 1 Medical Research Institute, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Republic of Korea
| | - Won-Young Lee
- 1 Medical Research Institute, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Republic of Korea.,2 Division of Endocrinology and Metabolism, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Republic of Korea
| | - Won-Serk Kim
- 1 Medical Research Institute, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Republic of Korea.,3 Department of Dermatology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Republic of Korea
| | - Yong-Taek Lee
- 1 Medical Research Institute, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Republic of Korea.,4 Department of Physical and Rehabilitation Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Republic of Korea
| | - Kyung Jae Yoon
- 1 Medical Research Institute, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Republic of Korea.,4 Department of Physical and Rehabilitation Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Republic of Korea
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Al-Bagdadi F, Schumacher J, Carter J, Tóth F, Henry RW. Determining Direction of Axonal Flow in the Equine Ramus Communicans by Ultrastructural Examination of the Plantar Nerves 2 Months after Transecting the Ramus. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2018; 24:64-68. [PMID: 29362000 DOI: 10.1017/s1431927617012818] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The ramus communicans, neural connection between medial and lateral plantar nerves of the horse, was transected to determine the degree to which medial and lateral plantar nerves contribute to the plantar ramus. After 2 months, sections of plantar nerves immediately proximal and distal to the communicating branch were collected and processed for electron microscopy. All examined nerves had undergone Wallerian degeneration and contained regenerating and mature fibers. Layers of the myelin sheath were separated by spaces and vacuoles, indicating demyelination of medial and lateral plantar nerves. Shrunken axons varied in diameter and were surrounded by an irregular axolemma. Shrunken axoplasm of both myelinated and non-myelinated fibers contained ruptured mitochondria and cristae, disintegrating cytoskeleton, and vacuoles of various sizes. The cytoplasm of neurolemmocytes contained various-sized vesicles, ruptured mitochondria within a fragile basal lamina and myelin whorls of multilayered structures indicative of Wallerian degeneration. These ultrastructural changes, found proximal and distal to the ramus in medial and lateral plantar nerves, suggest that axonal flow is bi-directional through the ramus communicans of the pelvic limbs of horses, a previously unreported finding. As well, maturity of nerves proximal and distal to the ramus indicates that all nerve fibers do not pass through the ramus.
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Affiliation(s)
- Fakhri Al-Bagdadi
- 1Department of Comparative Biomedical Sciences,School of Veterinary Medicine,Louisiana State University,Baton Rouge,LA 70803,USA
| | - Jim Schumacher
- 2Department of Large Animal Clinical Sciences,College of Veterinary Medicine,University of Tennessee,Knoxville,TN 37996,USA
| | - Jessi Carter
- 2Department of Large Animal Clinical Sciences,College of Veterinary Medicine,University of Tennessee,Knoxville,TN 37996,USA
| | - Ferenc Tóth
- 2Department of Large Animal Clinical Sciences,College of Veterinary Medicine,University of Tennessee,Knoxville,TN 37996,USA
| | - Robert W Henry
- 3College of Veterinary Medicine,Lincoln Memorial University,Harrogate,TN 37752,USA
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15
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Peterson M, Pingel R, Lagali N, Dahlin LB, Rolandsson O. Association between HbA 1c and peripheral neuropathy in a 10-year follow-up study of people with normal glucose tolerance, impaired glucose tolerance and Type 2 diabetes. Diabet Med 2017; 34:1756-1764. [PMID: 28929513 DOI: 10.1111/dme.13514] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/15/2017] [Indexed: 12/19/2022]
Abstract
AIMS To explore the association between HbA1c and sural nerve function in a group of people with normal glucose tolerance, impaired glucose tolerance or Type 2 diabetes. METHODS We conducted a 10-year follow-up study in 87 out of an original 119 participants. At study commencement (2004), 64 men and 55 women (mean age 61.1 years) with normal glucose tolerance (n=39), impaired glucose tolerance (n=29), or Type 2 diabetes (n=51) were enrolled. At the 2014 follow-up (men, n=46, women, n=41; mean age 71.1 years), 36, nine and 42 participants in the normal glucose tolerance, impaired glucose tolerance and Type 2 diabetes categories, respectively, were re-tested. Biometric data and blood samples were collected, with an electrophysiological examination performed on both occasions. RESULTS At follow-up, we measured the amplitude of the sural nerve in 74 of the 87 participants. The mean amplitude had decreased from 10.9 μV (2004) to 7.0 μV (2014; P<0.001). A 1% increase in HbA1c was associated with a ~1% average decrease in the amplitude of the sural nerve, irrespective of group classification. Crude and adjusted estimates ranged from -0.84 (95% CI -1.32, -0.37) to -1.25 (95% CI -2.31, -0.18). Although the mean conduction velocity of those measured at both occasions (n=73) decreased from 47.6 m/s to 45.8 m/s (P=0.009), any association with HbA1c level was weak. Results were robust with regard to potential confounders and missing data. CONCLUSIONS Our data suggest an association between sural nerve amplitude and HbA1c at all levels of HbA1c . Decreased amplitude was more pronounced than was diminished conduction velocity, supporting the notion that axonal degeneration is an earlier and more prominent effect of hyperglycaemia than demyelination.
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Affiliation(s)
- M Peterson
- Department of Public Health and Caring Sciences, Section of Family Medicine and Preventive Medicine, Uppsala University, Uppsala
| | - R Pingel
- Department of Public Health and Caring Sciences, Section of Family Medicine and Preventive Medicine, Uppsala University, Uppsala
| | - N Lagali
- Department of Clinical and Experimental Medicine, Section of Ophthalmology, Linköping University, Linköping
| | - L B Dahlin
- Department of Translational Medicine, Hand Surgery Lund University, Malmö
- Department of Hand Surgery, Skåne University Hospital, Malmö
| | - O Rolandsson
- Department of Public Health and Clinical Medicine, Section of Family Medicine, Umeå University, Umeå, Sweden
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16
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Rajabally YA, Stettner M, Kieseier BC, Hartung HP, Malik RA. CIDP and other inflammatory neuropathies in diabetes — diagnosis and management. Nat Rev Neurol 2017; 13:599-611. [DOI: 10.1038/nrneurol.2017.123] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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17
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Greig M, Tesfaye S, Selvarajah D, Wilkinson ID. Insights into the pathogenesis and treatment of painful diabetic neuropathy. HANDBOOK OF CLINICAL NEUROLOGY 2016; 126:559-78. [PMID: 25410244 DOI: 10.1016/b978-0-444-53480-4.00037-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Painful diabetic distal symmetrical polyneuropathy (painful DPN) is a puzzle with two important missing pieces: Firstly we still do not understand why only some patients with neuropathy experience painful symptoms; Secondly we still do not have a complete understanding of how nociception generated in the peripheral nervous system is processed by the central nervous system (CNS). Available treatments offer only symptom relief and there is currently no effective treatment based on arresting or reversing the progression of disease. Therefore the management of painful DPN remains less than optimal because the complex pathophysiology of nociception and pain perception in health and disease is incompletely understood. Studies of the peripheral nervous system are investigating the molecular processes involved in signal transduction that have the potential to be interrupted or modified to ease pain. Magnetic resonance imaging techniques are helping to elucidate central pain processing pathways and describe the translation of nociception to pain. Combining the knowledge from these two streams of enquiry we will soon be able to predict accurately who will develop painful DPN, how we can halt or reverse the condition, or who will respond to symptomatic treatments. Future developments in the treatment of painful DPN will be underpinned by decoding the peripheral and central mechanisms of pain. Research is focusing on these areas of enquiry in the hope that answers will lead to effective treatments to alleviate pain and reverse pathology for those suffering from painful DPN.
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Affiliation(s)
- Marni Greig
- Diabetes Department, Royal Hallamshire Hospital, Sheffield, UK
| | - Solomon Tesfaye
- Diabetes Department, Royal Hallamshire Hospital, Sheffield, UK.
| | | | - Iain D Wilkinson
- Academic Radiology, Department of Cardiovascular Science, Royal Hallamshire Hospital, Sheffield, UK
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18
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Khoshnoodi MA, Ebenezer GJ, Polydefkis M. Epidermal innervation as a tool to study human axonal regeneration and disease progression. Exp Neurol 2016; 287:358-364. [PMID: 27317299 DOI: 10.1016/j.expneurol.2016.06.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 06/10/2016] [Accepted: 06/13/2016] [Indexed: 01/14/2023]
Affiliation(s)
- Mohammad A Khoshnoodi
- Neurology, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Meyer 5-119, Baltimore, MD 21287, USA.
| | - Gigi J Ebenezer
- Neurology, Cutaneous Nerve Laboratory, Johns Hopkins University School of Medicine, The John G Rangos Building, 855 N. Wolfe Street, room 440, Baltimore, MD 21205, USA.
| | - Michael Polydefkis
- Neurology, Johns Hopkins University School of Medicine, Cutaneous Nerve Laboratory, Johns Hopkins Bayview EMG Laboratory, The John G Rangos Building, 855 N. Wolfe Street, room 435, Baltimore, MD 21205, USA.
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19
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Zgheib C, Hodges M, Hu J, Beason DP, Soslowsky LJ, Liechty KW, Xu J. Mechanisms of mesenchymal stem cell correction of the impaired biomechanical properties of diabetic skin: The role of miR-29a. Wound Repair Regen 2016; 24:237-46. [PMID: 26808714 DOI: 10.1111/wrr.12412] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 01/21/2016] [Indexed: 12/26/2022]
Abstract
Diabetic skin has impaired wound healing properties following injury. We have further shown that diabetic skin has weakened biomechanical properties at baseline. We hypothesize that the biomechanical properties of diabetic skin decline during the progression of the diabetic phenotype, and that this decline is due to the dysregulation of miR-29a, resulting in decreased collagen content. We further hypothesize that treatment with mesenchymal stem cells (MSCs) may improve diabetic wound healing by correction of the dysregulated miR-29a expression. We analyzed the biomechanical properties, collagen gene expression, collagen protein production, and miR-29a levels in skin harvested from 6 to 18 week old mice during the development of the diabetic phenotype. We also examined the correction of these impairments by both MSC treatment and the inhibition of miR-29a. Diabetic skin demonstrated a progressive impairment of biomechanical properties, decreased collagen content, and increased miR-29a levels during the development of the diabetic phenotype. MSC treatment decreased miR-29a levels, increased collagen content, and corrected the impaired biomechanical properties of diabetic skin. Additionally, direct inhibition of miR-29a also increased collagen content in diabetic skin. This decline in the biomechanical properties of diabetic skin during the progression of diabetes may increase the susceptibility of diabetic skin to injury and miR-29a appears to play a key role in this process.
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Affiliation(s)
- Carlos Zgheib
- Laboratory for Fetal and Regenerative Biology, Department of Surgery, University of Colorado Denver-Anschutz Medical Campus and Children's Hospital Colorado, Aurora, Colorado
| | - Maggie Hodges
- Laboratory for Fetal and Regenerative Biology, Department of Surgery, University of Colorado Denver-Anschutz Medical Campus and Children's Hospital Colorado, Aurora, Colorado
| | - Junyi Hu
- Laboratory for Fetal and Regenerative Biology, Department of Surgery, University of Colorado Denver-Anschutz Medical Campus and Children's Hospital Colorado, Aurora, Colorado
| | - David P Beason
- Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Louis J Soslowsky
- Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Kenneth W Liechty
- Laboratory for Fetal and Regenerative Biology, Department of Surgery, University of Colorado Denver-Anschutz Medical Campus and Children's Hospital Colorado, Aurora, Colorado
| | - Junwang Xu
- Laboratory for Fetal and Regenerative Biology, Department of Surgery, University of Colorado Denver-Anschutz Medical Campus and Children's Hospital Colorado, Aurora, Colorado
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Javed S, Alam U, Malik RA. Burning through the pain: treatments for diabetic neuropathy. Diabetes Obes Metab 2015; 17:1115-25. [PMID: 26179288 DOI: 10.1111/dom.12535] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Revised: 07/02/2015] [Accepted: 07/05/2015] [Indexed: 01/17/2023]
Abstract
The rise in the global burden of diabetes is spurring an increase in the prevalence of its complications. Diabetic peripheral neuropathy (DPN) is a common and devastating complication of diabetes, with multiple clinical manifestations. The most common is a symmetrical length-dependent dysfunction and damage of peripheral nerves. The management of DPN rests on three tenets: intensive glycaemic control, even though the evidence of benefit is questionable in people with type 2 diabetes; pathogenetic therapies; and symptomatic treatment. A number of pathogenetic treatments have been evaluated in phase III clinical trials, including α-lipoic acid (stems reactive oxygen species formation), benfotiamine (prevents vascular damage) and aldose-reductase inhibitors (reduce flux through the polyol pathway), protein kinase C inhibitors (prevent hyperglycaemia-induced activation of protein kinase C), nerve growth factors (stimulate nerve regeneration) and Actovegin® (improves tissue glucose and oxygen uptake). However, none have gained US Food and Drug Administration or European Medicines Agency (EMA) approval, questioning the validity of current trial designs and the endpoints deployed to define efficacy. For painful diabetic neuropathy, clinical guidelines recommend: atypical analgesics for pain relief, including duloxetine and amitriptyline; the γ-aminobutyric acid analogues gabapentin and pregabalin; opioids, including Tapentadol; and topical agents such as lidocaine and capsaicin. No single effective treatment exists for painful DPN, highlighting a growing need for studies to evaluate more potent and targeted drugs, as well as combinations. A number of novel potential candidates, including erythropoietin analogues and angiotensin II type 2 receptor anatagonists are currently being evaluated in phase II clinical trials.
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Affiliation(s)
- S Javed
- Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, Manchester, UK
| | - U Alam
- Central Manchester University Hospitals, Manchester, UK
| | - R A Malik
- Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, Manchester, UK
- Weill-Cornell Medical College-Qatar, Doha, Qatar
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21
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Schuelert N, Gorodetskaya N, Just S, Doods H, Corradini L. Electrophysiological characterization of spinal neurons in different models of diabetes type 1- and type 2-induced neuropathy in rats. Neuroscience 2015; 291:146-54. [PMID: 25686525 DOI: 10.1016/j.neuroscience.2015.02.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 01/15/2015] [Accepted: 02/03/2015] [Indexed: 10/24/2022]
Abstract
Diabetic polyneuropathy (DPN) is a devastating complication of diabetes. The underlying pathogenesis of DPN is still elusive and an effective treatment devoid of side effects presents a challenge. There is evidence that in type-1 and -2 diabetes, metabolic and morphological changes lead to peripheral nerve damage and altered central nociceptive transmission, which may contribute to neuropathic pain symptoms. We characterized the electrophysiological response properties of spinal wide dynamic range (WDR) neurons in three diabetic models. The streptozotocin (STZ) model was used as a drug-induced model of type-1 diabetes, and the BioBreeding/Worcester (BB/Wor) and Zucker diabetic fatty (ZDF) rat models were used for genetic DPN models. Data were compared to the respective control group (BB/Wor diabetic-resistant, Zucker lean (ZL) and saline-injected Wistar rat). Response properties of WDR neurons to mechanical stimulation and spontaneous activity were assessed. We found abnormal response properties of spinal WDR neurons in all diabetic rats but not controls. Profound differences between models were observed. In BB/Wor diabetic rats evoked responses were increased, while in ZDF rats spontaneous activity was increased and in STZ rats mainly after discharges were increased. The abnormal response properties of neurons might indicate differential pathological, diabetes-induced, changes in spinal neuronal transmission. This study shows for the first time that specific electrophysiological response properties are characteristic for certain models of DPN and that these might reflect the diverse and complex symptomatology of DPN in the clinic.
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Affiliation(s)
- N Schuelert
- Department of CNS Diseases Research, Boehringer Ingelheim Pharma GmbH & Co KG, 88397 Biberach, Germany.
| | - N Gorodetskaya
- Department of CNS Diseases Research, Boehringer Ingelheim Pharma GmbH & Co KG, 88397 Biberach, Germany
| | - S Just
- Department of CNS Diseases Research, Boehringer Ingelheim Pharma GmbH & Co KG, 88397 Biberach, Germany
| | - H Doods
- Department of CNS Diseases Research, Boehringer Ingelheim Pharma GmbH & Co KG, 88397 Biberach, Germany
| | - L Corradini
- Department of CNS Diseases Research, Boehringer Ingelheim Pharma GmbH & Co KG, 88397 Biberach, Germany
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Dominguez JM, Yorek MA, Grant MB. Combination therapies prevent the neuropathic, proinflammatory characteristics of bone marrow in streptozotocin-induced diabetic rats. Diabetes 2015; 64:643-53. [PMID: 25204979 PMCID: PMC4876792 DOI: 10.2337/db14-0433] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We previously showed that peripheral neuropathy of the bone marrow was associated with loss of circadian rhythmicity of stem/progenitor cell release into the circulation. Bone marrow neuropathy results in dramatic changes in hematopoiesis that lead to microvascular complications, inflammation, and reduced endothelial repair. This series of events represents early pathogenesis before development of diabetic retinopathy. In this study we characterized early alterations within the bone marrow of streptozotocin (STZ)-induced diabetic rats following treatments that prevent experimental peripheral neuropathy. We asked whether bone marrow neuropathy and the associated bone marrow pathology were reversed with treatments that prevent peripheral neuropathy. Three strategies were tested: inhibition of neutral endopeptidase, inhibition of aldose reductase plus lipoic acid supplementation, and insulin therapy with antioxidants. All strategies prevented loss of nerve conduction velocity resulting from STZ-induced diabetes and corrected the STZ-induced diabetes-associated increase of immunoreactivity of neuropeptide Y, tyrosine hydroxylase, and somatostatin. The treatments also reduced concentrations of interleukin-1β, granulocyte colony-stimulating factor, and matrix metalloproteinase 2 in STZ-induced diabetic bone marrow supernatant and decreased the expression of NADPH oxidase 2, nitric oxide synthase 2, and nuclear factor-κB1 mRNA in bone marrow progenitor cells. These therapies represent novel approaches to attenuate the diabetic phenotype within the bone marrow and may constitute an important therapeutic strategy for diabetic microvascular complications.
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Affiliation(s)
- James M Dominguez
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL
| | - Mark A Yorek
- Department of Veterans Affairs, Iowa City VA Health Care System, Iowa City, IA Department of Internal Medicine, University of Iowa, Iowa City, IA
| | - Maria B Grant
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN
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Abstract
SIGNIFICANCE Mitochondrial dynamics describes the continuous change in the position, size, and shape of mitochondria within cells. The morphological and functional complexity of neurons, the remarkable length of their processes, and the rapid changes in metabolic requirements arising from their intrinsic excitability render these cells particularly dependent on effective mitochondrial function and positioning. The rules that govern these changes and their functional significance are not fully understood, yet the dysfunction of mitochondrial dynamics has been implicated as a pathogenetic factor in a number of diseases, including disorders of the central and peripheral nervous systems. RECENT ADVANCES In recent years, a number of mutations of genes encoding proteins that play important roles in mitochondrial dynamics and function have been discovered in patients with Charcot-Marie-Tooth (CMT) disease, a hereditary peripheral neuropathy. These findings have directly linked mitochondrial pathology to the pathology of peripheral nerve and have identified certain aspects of mitochondrial dynamics as potential early events in the pathogenesis of CMT. In addition, mitochondrial dysfunction has now been implicated in the pathogenesis of noninherited neuropathies, including diabetic and inflammatory neuropathies. CRITICAL ISSUES The role of mitochondria in peripheral nerve diseases has been mostly examined in vitro, and less so in animal models. FUTURE DIRECTIONS This review examines available evidence for the role of mitochondrial dynamics in the pathogenesis of peripheral neuropathies, their relevance in human diseases, and future challenges for research in this field.
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Affiliation(s)
- Marija Sajic
- Department of Neuroinflammation, UCL Institute of Neurology , Queen Square, London, United Kingdom
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Sensory correlates of pain in peripheral neuropathies. Clin Neurophysiol 2014; 125:1048-58. [DOI: 10.1016/j.clinph.2013.09.038] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Revised: 08/26/2013] [Accepted: 09/30/2013] [Indexed: 01/04/2023]
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Didangelos T, Doupis J, Veves A. Painful diabetic neuropathy: clinical aspects. HANDBOOK OF CLINICAL NEUROLOGY 2014; 126:53-61. [PMID: 25410214 DOI: 10.1016/b978-0-444-53480-4.00005-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Painful diabetic neuropathy (PDN) is one of several clinical syndromes in patients with diabetic peripheral neuropathy (DPN) and presents a major challenge for optimal management. The epidemiology of PDN has not been extensively studied. On the basis of available data, the prevalence of pain ranges from 10% to 20% in patients with diabetes and from 40% to 50% in those with diabetic neuropathy. Neuropathic pain can be disabling and devastating, with a significant impact on the patient's quality of life and associated healthcare cost. Pathophysiologic mechanisms underlying PDN are similar to other neuropathic pain disorders and broadly invoke peripheral and central sensitization. The natural course of PDN is variable, with the majority of patients experiencing spontaneous improvement and resolution of pain. Quantifying neuropathic pain is difficult, especially in clinical practice, but has improved recently in clinical trials with the development of neuropathic pain-specific tools, such as the Neuropathic Pain Questionnaire and the Neuropathic Pain Symptom Inventory. Hyperglycemia-induced pathways result in nerve dysfunction and damage, which lead to hyperexcitable peripheral and central pathways of pain. Glycemic control may prevent or partially reverse DPN and modulate PDN.
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Affiliation(s)
- Triantafyllos Didangelos
- 1st Propedeutic Department of Internal Medicine, Medical School, Aristotle University of Thessaloniki, "AHEPA" Hospital, Greece
| | - John Doupis
- Internal Medicine and Diabetes Department, Salamis Naval Hospital, Salamis, Greece
| | - Aristidis Veves
- Microcirculation Laboratory and Joslin-Beth Israel Deaconess Foot Center, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA.
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Lee-Kubli CA, Mixcoatl-Zecuatl T, Jolivalt CG, Calcutt NA. Animal models of diabetes-induced neuropathic pain. Curr Top Behav Neurosci 2014; 20:147-70. [PMID: 24510303 DOI: 10.1007/7854_2014_280] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Neuropathy will afflict over half of the approximately 350 million people worldwide who currently suffer from diabetes and around one-third of diabetic patients with neuropathy will suffer from painful symptoms that may be spontaneous or stimulus evoked. Diabetes can be induced in rats or mice by genetic, dietary, or chemical means, and there are a variety of well-characterized models of diabetic neuropathy that replicate either type 1 or type 2 diabetes. Diabetic rodents display aspects of sensorimotor dysfunction such as stimulus-evoked allodynia and hyperalgesia that are widely used to model painful neuropathy. This allows investigation of pathogenic mechanisms and development of potential therapeutic interventions that may alleviate established pain or prevent onset of pain.
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Abstract
As ensheathing and secretory cells, Schwann cells are a ubiquitous and vital component of the endoneurial microenvironment of peripheral nerves. The interdependence of axons and their ensheathing Schwann cells predisposes each to the impact of injury in the other. Further, the dependence of the blood-nerve interface on trophic support from Schwann cells during development, adulthood, and after injury suggests these glial cells promote the structural and functional integrity of nerve trunks. Here, the developmental origin, injury-induced changes, and mature myelinating and nonmyelinating phenotypes of Schwann cells are reviewed prior to a description of nerve fiber pathology and consideration of pathogenic mechanisms in human and experimental diabetic neuropathy. A fundamental role for aldose-reductase-containing Schwann cells in the pathogenesis of diabetic neuropathy, as well as the interrelationship of pathogenic mechanisms, is indicated by the sensitivity of hyperglycemia-induced biochemical alterations, such as polyol pathway flux, formation of reactive oxygen species, generation of advanced glycosylation end products (AGEs) and deficient neurotrophic support, to blocking polyol pathway flux.
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Affiliation(s)
- Andrew P Mizisin
- Department of Pathology, School of Medicine, University of California San Diego, La Jolla, CA, USA.
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Abstract
Pathologic study of a disease provides insights into the precise mechanisms and targets of damage and may provide insights into new therapies. The main targets in diabetic neuropathy are myelinated and unmyelinated fibers as dysfunction and damage to them explains the symptoms of painful neuropathy and the major end points of foot ulceration and amputation as well as mortality. Demyelination and axonal degeneration are established hallmarks of the pathology of human diabetic neuropathy and were derived from pioneering light and electronmicroscopic studies of sural nerve biopsies in the late 1960s and early 1970s. Additional abnormalities, which are relevant to the pathogenesis of human diabetic neuropathy, include pathology of the microvessels and extracellular space. Intraepidermal and sudomotor nerve quantification in skin biopsies provides a minimally invasive means for the detection of early nerve damage. Studies of muscle biopsies are limited and show significant alterations in the expression of neurotrophins, but limited changes in muscle fiber size and capillary density.
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Affiliation(s)
- R A Malik
- Centre for Endocrinology and Diabetes, Institute of Human Development, Central Manchester University Hospitals NHS Foundation Trust, Manchester, UK; Weill Cornell Medical College in Qatar, Doha, Qatar.
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Cheng HT, Dauch JR, Porzio MT, Yanik BM, Hsieh W, Smith AG, Singleton JR, Feldman EL. Increased axonal regeneration and swellings in intraepidermal nerve fibers characterize painful phenotypes of diabetic neuropathy. THE JOURNAL OF PAIN 2013; 14:941-7. [PMID: 23685187 PMCID: PMC3994562 DOI: 10.1016/j.jpain.2013.03.005] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 01/23/2013] [Accepted: 03/11/2013] [Indexed: 01/25/2023]
Abstract
UNLABELLED We examined changes in intraepidermal nerve fibers (IENFs) to differentiate patients with diabetic neuropathy (DN) and diabetic neuropathic pain (DN-P) from those with DN without pain (DN-NOP). Punch skin biopsies were collected from the proximal thigh (PT) and distal leg (DL) of normal subjects, patients with type 2 diabetes without evidence of DN (DM), or DN-P and DN-NOP patients. Protein gene product 9.5-positive (PGP+) immunohistochemistry was used to quantify total IENF, and growth-associated protein 43 (GAP43) for regenerating IENF. Compared to normal subjects and patients with type 2 diabetes without evidence of DN, both DN-P and DN-NOP have reduced PGP+ IENF densities in DL and PT. Although GAP43+ IENF densities were also reduced in DL for both DN-P and DN-NOP, the GAP43+ IENF densities in PT of DN-P remained at the control levels. Higher GAP43/PGP ratios were detected in DN-P compared to DN-NOP in the DL and PT. In parallel, increased numbers of axonal swellings per PGP+ fiber (axonal swelling/PGP) were detected in DN-P compared to normal subjects, patients with type 2 diabetes without evidence of DN, and DN-NOP in the DL. These axonal swellings were positive for tropomyosin-receptor-kinase A and substance P, suggesting that they are associated with nociception. PERSPECTIVE Among patients with DN, the ratios of GAP43/PGP and axonal swelling/PGP are likely to differentiate painful from painless phenotypes.
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Affiliation(s)
- Hsinlin T Cheng
- Department of Neurology, University of Michigan Medical Center, Ann Arbor, Michigan 48109-2200, USA.
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Nishida N, Yamagishi SI, Mizukami H, Yagihashi S. Impaired nerve fiber regeneration in axotomized peripheral nerves in streptozotocin-diabetic rats. J Diabetes Investig 2013; 4:533-9. [PMID: 24843706 PMCID: PMC4020247 DOI: 10.1111/jdi.12115] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 05/07/2013] [Accepted: 05/14/2013] [Indexed: 11/28/2022] Open
Abstract
Aim/Introduction Impaired nerve fiber regeneration is a salient feature of diabetic neuropathy. Its pathogenesis is still unclear. We attempted to characterize the structure of regenerated myelinated fibers after transection in streptozotocin‐diabetic rats. Materials and Methods Streptozotocin‐diabetic rats underwent transection of the sciatic nerve. Two and 4 weeks post‐axotomy, regenerated myelinated fibers of the cut end and fibers at its proximal site were morphometrically examined. Non‐diabetic control rats with axotomy were also examined for comparison. Results At 4 weeks post‐axotomy, diabetic rats showed an increased myelinated fiber density and total fiber number with a trend toward reduced fiber size at the cut end compared with those in control rats. The average number of myelin lamellae relative to axonal size in regenerated fibers at the cut end was significantly reduced in diabetic rats compared with that in control rats. The proximal site showed a reduced size of fibers and axons in both diabetic and control rats to a similar extent compared with those in a non‐axotomized state. At 2 weeks post‐axotomy, these findings were less apparent. Conclusions The nerves of diabetic rats when axotomized undergo impaired regeneration characterized by increased fiber density with hypomyelination.
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Affiliation(s)
- Naoki Nishida
- Department of Pathology and Molecular Medicine Hirosaki University Graduate School of Medicine Hirosaki Japan ; Department of Legal Medicine Graduate School of Medicine and Pharmaceutical Sciences University of Toyama Toyama Japan
| | - Shin-Ichiro Yamagishi
- Department of Pathology and Molecular Medicine Hirosaki University Graduate School of Medicine Hirosaki Japan
| | - Hiroki Mizukami
- Department of Pathology and Molecular Medicine Hirosaki University Graduate School of Medicine Hirosaki Japan
| | - Soroku Yagihashi
- Department of Pathology and Molecular Medicine Hirosaki University Graduate School of Medicine Hirosaki Japan
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Hannon HE, Atchison WD. Omega-conotoxins as experimental tools and therapeutics in pain management. Mar Drugs 2013; 11:680-99. [PMID: 23470283 PMCID: PMC3705365 DOI: 10.3390/md11030680] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 02/14/2013] [Accepted: 02/15/2013] [Indexed: 12/24/2022] Open
Abstract
Neuropathic pain afflicts a large percentage of the global population. This form of chronic, intractable pain arises when the peripheral or central nervous systems are damaged, either directly by lesion or indirectly through disease. The comorbidity of neuropathic pain with other diseases, including diabetes, cancer, and AIDS, contributes to a complex pathogenesis and symptom profile. Because most patients present with neuropathic pain refractory to current first-line therapeutics, pharmaceuticals with greater efficacy in pain management are highly desired. In this review we discuss the growing application of ω-conotoxins, small peptides isolated from Conus species, in the management of neuropathic pain. These toxins are synthesized by predatory cone snails as a component of paralytic venoms. The potency and selectivity with which ω-conotoxins inhibit their molecular targets, voltage-gated Ca2+ channels, is advantageous in the treatment of neuropathic pain states, in which Ca2+ channel activity is characteristically aberrant. Although ω-conotoxins demonstrate analgesic efficacy in animal models of neuropathic pain and in human clinical trials, there remains a critical need to improve the convenience of peptide drug delivery methods, and reduce the number and severity of adverse effects associated with ω-conotoxin-based therapies.
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Affiliation(s)
- Heidi E Hannon
- Department of Pharmacology & Toxicology, Michigan State University, East Lansing, MI 48824, USA.
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Severo Do Nascimento P, Lovatel GA, Ilha J, Schaan BD, Achaval M. Diabetes increases mechanical sensitivity and causes morphological abnormalities in the sural nerve that are prevented by treadmill training. Muscle Nerve 2012; 47:46-52. [DOI: 10.1002/mus.23450] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/01/2012] [Indexed: 01/28/2023]
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Dolu N, Ozesmi C, Comu N, Süer C, Gölgeli A. EFFECT OF HYPERGLYCEMIA ON ELECTRODERMAL ACTIVITY IN DIABETIC RATS. Int J Neurosci 2009; 116:715-29. [PMID: 16753897 DOI: 10.1080/00207450600675027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
This study investigated the relationship between hyperglycemia and electrodermal activity (EDA) parameters in streptozotocin (STZ) induced diabetic rats. The article evaluates the course of development of neurophysiological alterations in the peripheral nervous system in diabetic rats through EDA. Rats were made diabetic using a moderate dose of STZ (DI) and high dose (DII). The placebo group (P) was injected with physiological saline. EDA was recorded 1 h before the injection (beginning, 0, day), 1st day (one day after the injection) and 10th day. Skin conductance level (SCL) was lower in DII than P on the 1st and the 10th days. The SCL and SC fluctuation rate (SCFr) of DI were significantly lower on the 10th day compared to their first record. SC response rate (SCRr) was lower on the 10th day compared to the 1st day, in the DI. In the DI, SCL, SC fluctuation rate (SCFr) and SC response rate (SCRr) were lower on the 10th day compared to the 1st day. The DII was statistically higher in electrodermal non-responsiveness compared to other groups on the 1st day. The results obtained show that hyperglycemia affects the peripheral nervous system, and EDA parameters are affected by blood glucose level. It is suggested that EDA is a simple and non-invasive electrophysiological method in early diagnosis of diabetic neuropathy.
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Affiliation(s)
- Nazan Dolu
- University of Erciyes Faculty of Medicine Department of Physiology, Kayseri, Turkey.
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35
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Veves A, Backonja M, Malik RA. Painful diabetic neuropathy: epidemiology, natural history, early diagnosis, and treatment options. PAIN MEDICINE 2009; 9:660-74. [PMID: 18828198 DOI: 10.1111/j.1526-4637.2007.00347.x] [Citation(s) in RCA: 246] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
OBJECTIVE To facilitate the clinician's understanding of the basis and treatment of painful diabetic neuropathy (PDN). BACKGROUND PDN is one of several clinical syndromes in patients with diabetic peripheral neuropathy (DPN) and presents a major challenge for optimal management. METHODS A systematic review of the literature was undertaken for articles specific to PDN, using Medline databases between 1966 and 2007. RESULTS The epidemiology of PDN has not been well established and on the basis of available data the prevalence of pain is 10% to 20% in patients with diabetes and from 40% to 50% in those with diabetic neuropathy. It has a significant impact on the quality of life and health care costs. Pathophysiologic mechanisms underlying PDN are similar to other neuropathic pain disorders and are broadly characterized as peripheral and central sensitization. The natural course of PDN is variable, with many patients experiencing spontaneous improvement and resolution of pain. Hyperglycemia-induced pathways result in nerve dysfunction and damage, which lead to hyperexcitable peripheral and central pathways of pain. Glycemic control may prevent or partially reverse DPN and modulate PDN. Quantifying neuropathic pain is difficult, especially for clinical trials, although this has improved recently with the development of neuropathic pain-specific tools, such as the Neuropathic Pain Questionnaire and the Neuropathic Pain Symptom Inventory. Current therapeutic options are limited to symptomatic treatment and are similar to other types of neuropathic pain. CONCLUSIONS A better understanding of the peripheral and central mechanisms resulting in PDN is likely to promote the development of more targeted and effective treatment.
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Affiliation(s)
- Aristidis Veves
- Microcirculation Laboratory, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
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36
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Fujita Y, Fukushima M, Suzuki H, Taniguchi A, Nakai Y, Kuroe A, Yasuda K, Hosokawa M, Yamada Y, Inagaki N, Seino Y. Short-term intensive glycemic control improves vibratory sensation in type 2 diabetes. Diabetes Res Clin Pract 2008; 80:e16-9. [PMID: 18262304 DOI: 10.1016/j.diabres.2007.12.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2007] [Accepted: 12/12/2007] [Indexed: 11/18/2022]
Abstract
Strict long-term glycemic control has been reported to prevent or improve diabetic peripheral neuropathy, but the effects of short-term glycemic control have not been clarified in patients with type 2 diabetes. To investigate reversibility of impaired vibratory sensation by short-term glycemic control, we used the TM31 liminometer and C64 tuning fork methods to measure peripheral neuropathy. Thirty-one type 2 diabetes patients with poor glycemic control (HbA1c: 10.8+/-0.4%, mean+/-S.E.M., range from 7.9% to 16.2%) were administered strict glycemic control. Vibratory sensation before and after short-term glycemic control was evaluated, and the metabolic profile including plasma glucose, HbA1c, total cholesterol, HDL cholesterol, triglyceride, and free fatty acid (FFA) was measured. After 20.0+/-2.1 days of strict glycemic control, vibratory sensation improved significantly in both upper and lower extremities, assessed by TM31 liminometer and C64 tuning fork. Along with the improved glycemic control, lipid metabolism (total cholesterol, triglyceride and FFA) was significantly improved. Thus, short-term intensive glycemic control can improve vibratory sensation, metabolic changes in glucose and lipid metabolism being the factors responsible for improved of peripheral nerve function.
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Affiliation(s)
- Yoshihito Fujita
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
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Sullivan KA, Lentz SI, Roberts JL, Feldman EL. Criteria for creating and assessing mouse models of diabetic neuropathy. Curr Drug Targets 2008; 9:3-13. [PMID: 18220709 DOI: 10.2174/138945008783431763] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Diabetic neuropathy (DN) is a serious and debilitating complication of both type 1 and type 2 diabetes. Despite intense research efforts into multiple aspects of this complication, including both vascular and neuronal metabolic derangements, the only treatment remains maintenance of euglycemia. Basic research into the mechanisms responsible for DN relies on using the most appropriate animal model. The advent of genetic manipulation has moved mouse models of human disease to the forefront. The ability to insert or delete genes affected in human patients offers unique insight into disease processes; however, mice are still not humans and difficulties remain in interpreting data derived from these animals. A number of studies have investigated and described DN in mice but it is difficult to compare these studies with each other or with human DN due to experimental differences including background strain, type of diabetes, method of induction and duration of diabetes, animal age and gender. This review describes currently used DN animal models. We followed a standardized diabetes induction protocol and designed and implemented a set of phenotyping parameters to classify the development and severity of DN. By applying standard protocols, we hope to facilitate the comparison and characterization of DN across different background strains in the hope of discovering the most human like model in which to test potential therapies.
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Affiliation(s)
- Kelli A Sullivan
- University of Michigan, Departments of Neurology and Internal Medicine, USA
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Morrison JFB, Sheen R, Dhanasekaran S, Mensah-Brown EPK. Long-term changes in sympathetic innervation in the corpus cavernosum of the STZ-diabetic rat. Int J Impot Res 2007; 19:509-16. [PMID: 17568762 DOI: 10.1038/sj.ijir.3901564] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The noradrenaline (NA) concentration in the rat corpus cavernosum (CC) increased to approximately 350% of control values after about 8 weeks of hyperglycaemia induced by the intraperitoneal injection of streptozotocin (STZ) at 10 weeks of age. These changes were maintained for at least a further 32 weeks of hyperglycaemia and occurred without any significant change in the weight in the tissue. Smaller but significant increases in NA concentration occurred in the glans penis (GP) reaching 150-175% of the control levels during the period of prolonged hyperglycaemia. In contrast, there was no significant change in the NA concentration in the penile urethra. Measurements have also been made that relate to changes in the synthesis and reuptake of NA in the CC during the period during which high NA concentration is maintained. Immunohistochemical studies for the synthetic enzyme tyrosine hydroxylase in the CC indicate that the intensity of staining in the tissue had increased after 10, 20 and 32 weeks of hyperglycaemia, relative to the tissues from control animals. Dilated nerve fibres and engorged endings were present in the CC of the diabetic animals at these times. Reuptake of tritiated NA by the terminal axonal membranes in the CC was raised to 181% of control values after 12 weeks of hyperglycaemia (P<0.05), but later declined to values that are not significantly different from the control levels (after 26 and 64 weeks of hyperglycaemia). There are few studies of the effects of prolonged diabetes on functional aspects of sympathetic postganglionic neurones in the CC, and this paper suggests that the changes described represent remodelling of noradrenergic axonal terminals starting about after 8-10 weeks of hyperglycaemia; this delay in onset of the neuropathic changes is also a feature of type I diabetes in humans.
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Affiliation(s)
- J F B Morrison
- Department of Physiology, Faculty of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates.
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Paré M, Albrecht PJ, Noto CJ, Bodkin NL, Pittenger GL, Schreyer DJ, Tigno XT, Hansen BC, Rice FL. Differential hypertrophy and atrophy among all types of cutaneous innervation in the glabrous skin of the monkey hand during aging and naturally occurring type 2 diabetes. J Comp Neurol 2007; 501:543-67. [PMID: 17278131 DOI: 10.1002/cne.21262] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Diabetic neuropathy (DN) is a common severe complication of type 2 diabetes. The symptoms of chronic pain, tingling, and numbness are generally attributed to small fiber dysfunction. However, little is known about the pathology among innervation to distal extremities, where symptoms start earliest and are most severe, and where the innervation density is the highest and includes a wide variety of large fiber sensory endings. Our study assessed the immunochemistry, morphology, and density of the nonvascular innervation in glabrous skin from the hands of aged nondiabetic rhesus monkeys and from age-matched monkeys that had different durations of spontaneously occurring type 2 diabetes. Age-related reductions occurred among all types of innervation, with epidermal C-fiber endings preferentially diminishing earlier than presumptive Adelta-fiber endings. In diabetic monkeys epidermal innervation density diminished faster, became more unevenly distributed, and lost immunodetectable expression of calcitonin gene-related peptide and capsaicin receptors, TrpV1. Pacinian corpuscles also deteriorated. However, during the first few years of hyperglycemia, a surprising hypertrophy occurred among terminal arbors of remaining epidermal endings. Hypertrophy also occurred among Meissner corpuscles and Merkel endings supplied by Abeta fibers. After longer-term hyperglycemia, Meissner corpuscle hypertrophy declined but the number of corpuscles remained higher than in age-matched nondiabetics. However, the diabetic Meissner corpuscles had an abnormal structure and immunochemistry. In contrast, the expanded Merkel innervation was reduced to age-matched nondiabetic levels. These results indicate that transient phases of substantial innervation remodeling occur during the progression of diabetes, with differential increases and decreases occurring among the varieties of innervation.
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Affiliation(s)
- Michel Paré
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, New York 12208, USA
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Abstract
Peripheral neuropathy, and specifically distal peripheral neuropathy (DPN), is one of the most frequent and troublesome complications of diabetes mellitus. It is the major reason for morbidity and mortality among diabetic patients. It is also frequently associated with debilitating pain. Unfortunately, our knowledge of the natural history and pathogenesis of this disease remains limited. For a long time hyperglycemia was viewed as a major, if not the sole factor, responsible for all symptomatic presentations of DPN. Multiple clinical observations and animal studies supported this view. The control of blood glucose as an obligatory step of therapy to delay or reverse DPN is no longer an arguable issue. However, while supporting evidence for the glycemic hypothesis has accumulated, multiple controversies accumulated as well. It is obvious now that DPN cannot be fully understood without considering factors besides hyperglycemia. Some symptoms of DPN may develop with little, if any, correlation with the glycemic status of a patient. It is also clear that identification of these putative non-glycemic mechanisms of DPN is of utmost importance for our understanding of failures with existing treatments and for the development of new approaches for diagnosis and therapy of DPN. In this work we will review the strengths and weaknesses of the glycemic hypothesis, focusing on clinical and animal data and on the pathogenesis of early stages and triggers of DPN other than hyperglycemia.
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Affiliation(s)
- Maxim Dobretsov
- Department of Anesthesiology, Slot 515, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, United States.
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Berghoff M, Kilo S, Hilz MJ, Freeman R. Differential impairment of the sudomotor and nociceptor axon-reflex in diabetic peripheral neuropathy. Muscle Nerve 2006; 33:494-9. [PMID: 16411196 DOI: 10.1002/mus.20497] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
It is not known whether C-fiber functional subclasses are differentially affected by diabetes mellitus or whether the patterns of C-fiber dysfunction are different between type 1 and type 2 diabetes. We therefore examined efferent sympathetic sudomotor and primary afferent nociceptor C-fiber function in diabetic patients. Acetylcholine (10%) was used to evoke C-fiber (axon-reflex)-mediated responses. The nociceptor (flare) response was measured using a laser Doppler device. The sudomotor response was quantified with silastic imprints. The nociceptor C-fiber-mediated flare response was reduced in type 2 diabetic patients (P < 0.008) but was similar to controls in type 1 diabetic patients. The sympathetic C-fiber-mediated responses, including sweat volume (P < 0.05) and the number of activated sweat glands (P = 0.003), were increased in patients with type 1 diabetes. There also was a trend toward a larger axon-reflex sweat area in patients with type 1 diabetes (P = 0.09). No differences in these sweat responses were found in patients with type 2 diabetes compared to controls. These findings suggest that the functional abnormalities in diabetic peripheral neuropathy are not homogeneous and that C-fiber subclasses are differentially affected in type 1 and 2 diabetes mellitus.
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Affiliation(s)
- Martin Berghoff
- Department of Neurology, University of Münster, Münster, Germany
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42
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Kamiya H, Murakawa Y, Zhang W, Sima AAF. Unmyelinated fiber sensory neuropathy differs in type 1 and type 2 diabetes. Diabetes Metab Res Rev 2005; 21:448-58. [PMID: 15747389 DOI: 10.1002/dmrr.541] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Neuropathic pain is common in diabetic patients. Degeneration of sensory C-fibers in peripheral nerve plays a prominent role in the generation of neuropathic pain. We examined degenerative changes of C-fibers in two rat models with type 1 and type 2 diabetes. METHODS Type 1 insulinopenic BB/Wor and type 2 hyperinsulinemic diabetic BBZDR/Wor-rats of 8 months duration with equal exposure to hyperglycemia were examined. Thermal hyperalgesia was monitored using an infrared thermal probe. C-fiber size, number, frequencies of denervated Schwann cells, regenerating C-fibers, type 2 axon/Schwann cell relationship and collagen pockets in the sural nerve were examined morphometrically. Neurotrophic receptor expression was examined by Western blotting. Neurotrophins and neuropeptides were examined by ELISA. RESULTS Type 1 rats showed increased thermal hyperalgesia followed by a decrease. Hyperalgesia in type 2 rats showed a slower progression. These findings were associated with a 50% (p < 0.001) loss of C-fibers, increased frequencies of denervated Schwann cells (p < 0.001), regenerating fibers (p < 0.001), collagen pockets (p < 0.001) and type 2 axon/Schwann cell relationship (p < 0.001) in type 1, but not in type 2 rats. Expression of insulin receptor, IGF-1R, TrkA and C was decreased in BB/Wor rats, whereas BBZDR/Wor rats showed milder or no deficits. NGF and NT-3 in sciatic nerve and substance P and calcitonin gene-related peptide in dorsal root ganglia were decreased in type 1, but not in type 2 rats. CONCLUSION The more severe molecular, functional and morphometric abnormalities of nociceptive C-fibers in type 1 insulinopenic rats compared to type 2 hyperinsulinemic rats suggest that impaired insulin action may play a more important pathogenetic role than hyperglycemia per se.
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Affiliation(s)
- Hideki Kamiya
- Department of Pathology, Wayne State University, School of Medicine, Detroit, MI 48201, USA
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Malik RA, Tesfaye S, Newrick PG, Walker D, Rajbhandari SM, Siddique I, Sharma AK, Boulton AJM, King RHM, Thomas PK, Ward JD. Sural nerve pathology in diabetic patients with minimal but progressive neuropathy. Diabetologia 2005; 48:578-85. [PMID: 15729579 DOI: 10.1007/s00125-004-1663-5] [Citation(s) in RCA: 162] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2004] [Accepted: 11/17/2004] [Indexed: 10/25/2022]
Abstract
AIMS/HYPOTHESIS The early pathological features of human diabetic neuropathy are not clearly defined. Therefore we quantified nerve fibre and microvascular pathology in sural nerve biopsies from diabetic patients with minimal neuropathy. METHODS Twelve diabetic patients underwent detailed assessment of neuropathy and fascicular sural nerve biopsy at baseline, with repeat assessment of neuropathy 8.7+/-0.6 years later. RESULTS At baseline, neuropathic symptoms, neurological deficits, quantitative sensory testing, cardiac autonomic function and peripheral nerve electrophysiology showed minimal abnormality, which deteriorated at follow-up. Myelinated fibre density, fibre and axonal area, and g-ratio were normal but teased fibre studies showed paranodal abnormalities (p<0.001), segmental demyelination (p<0.01) and remyelination (p<0.01) without axonal degeneration. Unassociated Schwann cell profile density (p<0.04) and unmyelinated axon density (p<0.001) were increased and axon diameter was decreased (p<0.007). Endoneurial capillaries demonstrated basement membrane thickening (p<0.006), endothelial cell hyperplasia (p<0.004) and a reduction in luminal area (p<0.007). CONCLUSIONS/INTERPRETATION The early pathological features of human diabetic neuropathy include an abnormality of the myelinated fibre Schwann cell and unmyelinated fibre degeneration with regeneration. These changes are accompanied by a significant endoneurial microangiopathy.
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Affiliation(s)
- R A Malik
- Department of Medicine, Manchester Royal Infirmary, Oxford Road, Manchester, M13 9WL, UK.
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Polydefkis M, Hauer P, Sheth S, Sirdofsky M, Griffin JW, McArthur JC. The time course of epidermal nerve fibre regeneration: studies in normal controls and in people with diabetes, with and without neuropathy. Brain 2004; 127:1606-15. [PMID: 15128618 DOI: 10.1093/brain/awh175] [Citation(s) in RCA: 286] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We sought to develop and validate a standardized cutaneous nerve regeneration model and to define the rate of epidermal nerve fibre (ENF) regeneration first in healthy control subjects and then in neuropathic and neuropathy-free subjects with diabetes. Next, we assessed the effect of different factors on the rate of nerve fibre regeneration and investigated whether such an approach might offer insight into novel trial designs and outcome measures. All subjects had a standardized topical capsaicin dressing applied to the distal lateral thigh. ENF densities derived from skin biopsies were determined at baseline, after capsaicin treatment and at reinnervation time points. For each subject, the best fit line from post-denervation data was determined and the slope was used as the rate of regeneration. In healthy control subjects, regeneration was correlated with psychophysical sensory testing, electron microscopy studies and immunohistochemistry with alternative axonal membrane markers. Topical capsaicin application produced complete or nearly complete denervation of the epidermis in both control subjects and people with diabetes. The rate of regeneration was associated with the baseline ENF density (P < 0.001), but not age (P = 0.75), gender (P = 0.18), epidermal thickness (P = 0.4) or post-capsaicin treatment density (P = 0.7). ENF regeneration, as determined by recovery of ENF density, occurred at a rate of 0.177 +/- 0.075 fibres/mm/day in healthy control subjects and was significantly reduced in subjects with diabetes (0.074 +/- 0.064, P < 0.001) after adjusting for changes in baseline ENF density. Among subjects with diabetes, the presence of neuropathy was associated with a further reduction in regenerative rate (0.10 +/- 0.07 versus 0.04 +/- 0.03, P = 0.03), though diabetes type (P = 0.7), duration of diabetes (P = 0.3) or baseline glycated haemoglobin (P = 0.6) were not significant. These results have several implications. First, topical capsaicin application can produce a uniform epidermal nerve fibre injury that is safe and well tolerated, and offers an efficient strategy to measure and study nerve regeneration in man. Secondly, using our techniques, reduced rates of nerve regeneration were found in people with diabetes without evidence of neuropathy and indicate that abnormalities in peripheral nerve function are present early in diabetes, before signs or symptoms develop. These results suggest that regenerative neuropathy trials could include non-neuropathic subjects and that trial duration can be dramatically shortened.
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Affiliation(s)
- Michael Polydefkis
- Department of Neurology, The Johns Hopkins University, Baltimore, MD 21287, USA.
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Brumovsky PR, Bergman E, Liu HX, Hökfelt T, Villar MJ. Effect of a graded single constriction of the rat sciatic nerve on pain behavior and expression of immunoreactive NPY and NPY Y1 receptor in DRG neurons and spinal cord. Brain Res 2004; 1006:87-99. [PMID: 15047027 DOI: 10.1016/j.brainres.2003.09.085] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/11/2003] [Indexed: 01/28/2023]
Abstract
In the present study, the rat sciatic nerve was constricted to varying degrees using only one ligature with a very thin polyethylene sheath placed between nerve and ligature thread. Complete nerve transection was studied for comparison. With a 40-80% constriction of the nerve we observed allodynia to a similar extent as in the so-called Bennett model based on four loose ligatures. We also monitored changes in the expression of neuropeptide Y (NPY) and the NPY Y1 receptor (Y1R) in the lumbar 4-5 dorsal root ganglia (DRG) and dorsal horn and found upregulation of NPY and downregulation of the Y1R in DRG neurons after injury. These results indicate that similar peptide and receptor changes occur in this model as after axotomy and in other nerve injury models, although the immunohistochemical and behavioral changes seem to be dependent on the degree of constriction of the nerve. Thus, it seems relevant to monitor the degree of constriction when evaluating pain and other post-injury events. The possibility that some of the changes in NPY-ergic neurotransmission are related to the generation of allodynia is discussed; as well as the possibility to use this mononeuropathic model based on a single ligature nerve constriction (SLNC) as a complementary approach to other widely used pain models.
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Affiliation(s)
- P R Brumovsky
- Department of Neuroscience, Karolinska Institutet, Retzius Väg 8, S-171 77 Stockholm, Sweden.
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Joseph EK, Levine JD. Sexual dimorphism in the contribution of protein kinase C isoforms to nociception in the streptozotocin diabetic rat. Neuroscience 2003; 120:907-13. [PMID: 12927197 DOI: 10.1016/s0306-4522(03)00400-7] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The contribution of second messenger signaling, glucose level and sex hormones to sexual dimorphism in the streptozotocin model of diabetic painful peripheral neuropathy was evaluated. Streptozotocin induced elevation of blood glucose and mechanical hyperalgesia (measured by the Randall-Selitto paw-withdrawal test) were both greater in female rats. Ovariectomy abolished and estrogen implants reconstituted this sexual dimorphism; gonadectomy in males had no effect. An inhibitor of protein kinase Cepsilon attenuated hyperalgesia in males and ovariectomized females, but not in normal females or in ovariectomized females with estrogen implants, whereas inhibitors of protein kinase Cdelta attenuated hyperalgesia in females but not in males. Inhibitors of protein kinase A, protein kinase C (non-selective), protein kinase G and nitric oxide synthase attenuated hyperalgesia equally in both sexes. Higher blood glucose levels in diabetic females were also sex hormone dependent, and magnitude of hyperalgesia correlated with blood glucose level in diabetic male and female rats. These results demonstrate sexual dimorphism in diabetic hyperalgesia, mediated by sex hormone dependent differences in protein kinase Cepsilon and protein kinase Cdelta signaling and blood glucose levels and suggest that sex may be an important factor to be considered in the treatment of symptomatic diabetic neuropathy.
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Affiliation(s)
- E K Joseph
- Department of Medicine, Division of Neuroscience and Biomedical Sciences Program and UCSF-NIH Pain Center, Box 0440/Room C522, 521 Parnassus Avenue, University of California, San Francisco, CA 94143-0440, USA.
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Eaton SEM, Harris ND, Ibrahim S, Patel KA, Selmi F, Radatz M, Ward JD, Tesfaye S. Increased sural nerve epineurial blood flow in human subjects with painful diabetic neuropathy. Diabetologia 2003; 46:934-9. [PMID: 12819899 DOI: 10.1007/s00125-003-1127-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2002] [Revised: 03/18/2003] [Indexed: 12/13/2022]
Abstract
AIMS/HYPOTHESIS The pathogenesis of painful diabetic neuropathy remains unknown. As a consequence we still do not have any effective, rational treatments and a greater understanding of the mechanisms is urgently required. Previous studies have shown no consistent morphological differences in the nerves of patients with and without painful neuropathy. The aim of this study was to compare epineurial haemodynamics in patients with chronic painful and painless neuropathy. METHODS The techniques of microlightguide spectrophotometry and fluorescein angiography were used to measure epineurial intravascular oxygen saturation and blood flow respectively. Eleven patients with painful and eight with painless neuropathy were studied, with the groups matched carefully in terms of severity of neuropathy and diabetes control. RESULTS Intravascular oxygen saturation was higher in the painful neuropathy group compared to those without pain (median 73.8% vs 67.7%, respectively; p=0.021). Fluorescein rise time was also faster in those with painful symptoms (median 18.3 s vs 53.6 s; p=0.046) indicating higher epineurial blood flow in these subjects. CONCLUSION/INTERPRETATION These results indicate that there are distinct differences in haemodynamics within the epineurium of the sural nerve in subjects with painful and painless neuropathy. Haemodynamic factors could therefore have an important role in the pathogenesis of neuropathic pain and might offer further insight into potential treatments for this distressing condition.
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Affiliation(s)
- S E M Eaton
- Diabetes Research Unit, Royal Hallamshire Hospital, Glossop Road, Sheffield, UK
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Abstract
Diabetic sensorimotor polyneuropathy (DSP) remains the most common microvascular complication of both type I and type 2 diabetes, and poses a unique set of management challenges in the prevention of foot complications. Although different quantitative tests are available, the preliminary diagnosis of DSP can be reliably made using simple and rapid screening tests in the family physician's office or in the diabetes clinic. The Semmes-Weinstein 10-g monofilament examination is a popular, simple clinical modality for the prediction of early DSP, foot ulceration, and amputation, and, in turn, a predictor of mortality in patients with diabetes. The management of DSP is centered on optimal glycemic control, diligent foot care, and pain control as a means of preventing the progression of DSP and reducing the morbidity associated with foot complications.
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Affiliation(s)
- Bruce A Perkins
- Toronto General Hospital, University Health Network, 200 Elizabeth Street, Toronto, Ontario M5G 2C4, Canada
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Sima AAF. Diabetic neuropathy: pathogenetic background, current and future therapies. Expert Rev Neurother 2001; 1:225-238. [DOI: 10.1586/14737175.1.2.225] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
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Fehér D, Gyorffi A, Fazekas A. Neurogenic inflammation of gingivomucosal tissue in streptozotocin-diabetic rat. Arch Physiol Biochem 2001; 109:230-3. [PMID: 11880926 DOI: 10.1076/apab.109.3.230.11597] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Previously it was assumed that nerve fibres are involved in the neurogenic inflammation induced by mechanical or chemical irriations. It has been also suggested that in diabetes mellitus the unmyelinated small diameter fibers are impaired as a result of diabetic neuropathy. Therefore, our aim was to study the alterations of the nerve processes in the gingivomucosal tissue in streptozotocin (STZ)-diabetic rats. Light- and electronmicroscopical examinations were made to analyze the changes in nerve fibres. After one week of steptozotocin treatment, the gingivomucosal tissue had inflammatory cell infiltration and some degenerated nerve fibres were also observed. Dense mitochondria, disorganization of cell organelles, and appearance of myelin-like dense bodies were found in the axons of degenerared nerve fibres. Semiquantitative analysis showed that 14 +/- 4% of the unmyelinated nerve fibres degenerated after one week of STZ treatment. However, degeneration of the myelinated nerve fibers was not observed. Two weeks after STZ treatment, most of the unmyelinated and myelinated nerve fibers showed degeneration (86 +/- 5%) and the placement of the ligature revealed a non-inflammatory connective tissue adjacent to a normal epithelium. The myelin sheath was disrupted and dark axoplasm with cytolysosomes became manifest. These findings demonstrated that both unmyelinated and myelinated nerve fibers are altered and inflammatory reaction exists in the gingivomucosal tissue only in the early stage of diabetes mellitus.
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Affiliation(s)
- D Fehér
- Department of Anatomy, Histology and Embryology (Oral Morphology Group), Semmelweis University, Budapest, Hungary.
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