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Du Q, Huang L, Tang Y, Kang J, Ye W, Feng Z. Median Nerve Stimulation Attenuates Traumatic Brain Injury-Induced Comatose State by Regulating the Orexin-A/RasGRF1 Signaling Pathway. World Neurosurg 2022; 168:e19-e27. [PMID: 36064116 DOI: 10.1016/j.wneu.2022.07.085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 07/16/2022] [Accepted: 07/18/2022] [Indexed: 01/06/2023]
Abstract
BACKGROUND Despite the arousal effect of median nerve stimulation (MNS) being well documented in the clinical treatment of coma patients with traumatic brain injury (TBI), the mechanisms underlying the observed effect are still not completely understood. This study aimed to evaluate the protective effects and potential mechanism of MNS in comatose rats with TBI. METHODS A total of 60 rats were randomly divided into 5 groups: the control group, sham-stimulated group, MNS group, orexins receptor type 1 (OX1R) antagonist group, and antagonist control group. The free-fall drop method was used to establish a TBI model. After administrating MNS or OX1R antagonist, consciousness was evaluated. Protein levels in the prefrontal cortex were measured using an enzyme-linked immunosorbent assay, Western blotting, and immunofluorescence. RESULTS In the MNS group, tissue damage and consciousness state was markedly improved compared with that in the sham-stimulated group. Administration of the OX1R antagonist attenuated the beneficial effects of MNS in TBI-induced comatose rats. Additionally, MNS also significantly enhanced the expression of orexin-A/OX1R and the activation of Ras guanine nucleotide-releasing factor 1 (RasGRF1). CONCLUSIONS These data show that MNS exerts its wake-promoting effect by activating the OX1R-RasGRF1 pathway in TBI-induced comatose rats.
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Affiliation(s)
- Qing Du
- Department of Rehabilitation Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, People's Republic of China
| | - Lianghua Huang
- Department of Rehabilitation Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, People's Republic of China
| | - Yunliang Tang
- Department of Rehabilitation Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, People's Republic of China
| | - Junwei Kang
- Department of Rehabilitation Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, People's Republic of China
| | - Wen Ye
- Department of Rehabilitation Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, People's Republic of China
| | - Zhen Feng
- Department of Rehabilitation Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, People's Republic of China.
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Liu J, Ma AK, So KF, Lee VW, Chiu K. Mechanisms of electrical stimulation in eye diseases: A narrative review. ADVANCES IN OPHTHALMOLOGY PRACTICE AND RESEARCH 2022; 2:100060. [PMID: 37846384 PMCID: PMC10577855 DOI: 10.1016/j.aopr.2022.100060] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 04/14/2022] [Accepted: 05/01/2022] [Indexed: 10/18/2023]
Abstract
Background In the last two decades, electrical stimulation (ES) has been tested in patients with various eye diseases and shows great treatment potential in retinitis pigmentosa and optic neuropathy. However, the clinical application of ES in ophthalmology is currently limited. On the one hand, optimization and standardization of ES protocols is still an unmet need. On the other hand, poor understanding of the underlying mechanisms has hindered clinical exploitation. Main Text Numerous experimental studies have been conducted to identify the treatment potential of ES in eye diseases and to explore the related cellular and molecular mechanisms. In this review, we summarized the in vitro and in vivo evidence related to cellular and tissue response to ES in eye diseases. We highlighted several pathways that may be utilized by ES to impose its effects on the diseased retina. Conclusions Therapeutic effect of ES in retinal degenerative diseases might through preventing neuronal apoptosis, promoting neuronal regeneration, increasing neurotrophic factors production in Müller cells, inhibiting microglial activation, enhancing retinal blood flow, and modulating brain plasticity. Future studies are suggested to analyse changes in specific retinal cells for optimizing the treatment parameters and choosing the best fit ES delivery method in target diseases.
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Affiliation(s)
- Jinfeng Liu
- Department of Ophthalmology, The University of Hong Kong, SAR, Hong Kong, China
| | | | - Kwok Fai So
- Department of Ophthalmology, The University of Hong Kong, SAR, Hong Kong, China
- The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, SAR, Hong Kong, China
- Department of Psychology, The University of Hong Kong, SAR, Hong Kong, China
- Guangdong-Hong Kong-Macau Institute of Central Nervous System Regeneration, Jinan University, Guangzhou, China
| | - Vincent W.H. Lee
- Department of Ophthalmology, The University of Hong Kong, SAR, Hong Kong, China
| | - Kin Chiu
- The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, SAR, Hong Kong, China
- Department of Psychology, The University of Hong Kong, SAR, Hong Kong, China
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Erb C, Eckert S, Gindorf P, Köhler M, Köhler T, Neuhann L, Neuhann T, Salzmann N, Schmickler S, Ellrich J. Electrical neurostimulation in glaucoma with progressive vision loss. Bioelectron Med 2022; 8:6. [PMID: 35361287 PMCID: PMC8969331 DOI: 10.1186/s42234-022-00089-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 03/22/2022] [Indexed: 02/03/2023] Open
Abstract
Abstract
Background
The retrospective study provides real-world evidence for long-term clinical efficacy of electrical optic nerve stimulation (ONS) in glaucoma with progressive vision loss.
Methods
Seventy glaucoma patients (45 to 86 y) with progressive vision loss despite therapeutic reduction of intraocular pressure (IOP) underwent electrical ONS. Closed eyes were separately stimulated by bipolar rectangular pulses with stimulus intensities up to 1.2 mA sufficient to provoke phosphenes. Ten daily stimulation sessions within 2 weeks lasted about 80 min each. Right before ONS at baseline (PRE), vision loss was documented by static threshold perimetry and compared to the same assessment approximately 1 year afterwards (POST). Mean defect (MD) was defined as primary outcome parameter. Perimetries with a reliability factor (RF) of max. 20% were considered.
Results
Perimetry follow-up of 101 eyes in 70 patients fulfilled the criterion of a max. 20% RF. Follow-up was performed on average 362.2 days after ONS. MD significantly decreased from PRE 14.0 dB (median) to POST 13.4 dB (p < 0.01). 64 eyes in 49 patients showed constant or reduced MD as compared to baseline (PRE 13.4 dB vs. POST 11.2 dB). In 37 eyes of 30 patients, MD increased from PRE 14.9 dB to POST 15.6 dB.
Conclusions
Innovative treatments that preserve visual function through mechanisms other than lowering IOP are required for glaucoma with progressive vision loss. The present long-term data document progression halt in more than 63% of affected eyes after ONS and, thus, extend existing evidence from clinical trials.
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Zuo KJ, Gordon T, Chan KM, Borschel GH. Electrical stimulation to enhance peripheral nerve regeneration: Update in molecular investigations and clinical translation. Exp Neurol 2020; 332:113397. [PMID: 32628968 DOI: 10.1016/j.expneurol.2020.113397] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 06/16/2020] [Accepted: 06/27/2020] [Indexed: 02/06/2023]
Abstract
Peripheral nerve injuries are common and frequently result in incomplete functional recovery even with optimal surgical treatment. Permanent motor and sensory deficits are associated with significant patient morbidity and socioeconomic burden. Despite substantial research efforts to enhance peripheral nerve regeneration, few effective and clinically feasible treatment options have been found. One promising strategy is the use of low frequency electrical stimulation delivered perioperatively to an injured nerve at the time of surgical repair. Possibly through its effect of increasing intraneuronal cyclic AMP, perioperative electrical stimulation accelerates axon outgrowth, remyelination of regenerating axons, and reinnervation of end organs, even with delayed surgical intervention. Building on decades of experimental evidence in animal models, several recent, prospective, randomized clinical trials have affirmed electrical stimulation as a clinically translatable technique to enhance functional recovery in patients with peripheral nerve injuries requiring surgical treatment. This paper provides an updated review of the cellular physiology of electrical stimulation and its effects on axon regeneration, Level I evidence from recent prospective randomized clinical trials of electrical stimulation, and ongoing and future directions of research into electrical stimulation as a clinically feasible adjunct to surgical intervention in the treatment of patients with peripheral nerve injuries.
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Affiliation(s)
- Kevin J Zuo
- Division of Plastic & Reconstructive Surgery, University of Toronto, Toronto, ON, Canada; Neurosciences and Mental Health, SickKids Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Tessa Gordon
- Division of Plastic & Reconstructive Surgery, University of Toronto, Toronto, ON, Canada; Neurosciences and Mental Health, SickKids Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - K Ming Chan
- Division of Physical Medicine and Rehabilitation, University of Alberta, Edmonton, AB, Canada
| | - Gregory H Borschel
- Division of Plastic & Reconstructive Surgery, University of Toronto, Toronto, ON, Canada; Neurosciences and Mental Health, SickKids Research Institute, Hospital for Sick Children, Toronto, ON, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada.
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Adair D, Truong D, Esmaeilpour Z, Gebodh N, Borges H, Ho L, Bremner JD, Badran BW, Napadow V, Clark VP, Bikson M. Electrical stimulation of cranial nerves in cognition and disease. Brain Stimul 2020; 13:717-750. [PMID: 32289703 PMCID: PMC7196013 DOI: 10.1016/j.brs.2020.02.019] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 02/13/2020] [Accepted: 02/17/2020] [Indexed: 02/06/2023] Open
Abstract
The cranial nerves are the pathways through which environmental information (sensation) is directly communicated to the brain, leading to perception, and giving rise to higher cognition. Because cranial nerves determine and modulate brain function, invasive and non-invasive cranial nerve electrical stimulation methods have applications in the clinical, behavioral, and cognitive domains. Among other neuromodulation approaches such as peripheral, transcranial and deep brain stimulation, cranial nerve stimulation is unique in allowing axon pathway-specific engagement of brain circuits, including thalamo-cortical networks. In this review we amalgamate relevant knowledge of 1) cranial nerve anatomy and biophysics; 2) evidence of the modulatory effects of cranial nerves on cognition; 3) clinical and behavioral outcomes of cranial nerve stimulation; and 4) biomarkers of nerve target engagement including physiology, electroencephalography, neuroimaging, and behavioral metrics. Existing non-invasive stimulation methods cannot feasibly activate the axons of only individual cranial nerves. Even with invasive stimulation methods, selective targeting of one nerve fiber type requires nuance since each nerve is composed of functionally distinct axon-types that differentially branch and can anastomose onto other nerves. None-the-less, precisely controlling stimulation parameters can aid in affecting distinct sets of axons, thus supporting specific actions on cognition and behavior. To this end, a rubric for reproducible dose-response stimulation parameters is defined here. Given that afferent cranial nerve axons project directly to the brain, targeting structures (e.g. thalamus, cortex) that are critical nodes in higher order brain networks, potent effects on cognition are plausible. We propose an intervention design framework based on driving cranial nerve pathways in targeted brain circuits, which are in turn linked to specific higher cognitive processes. State-of-the-art current flow models that are used to explain and design cranial-nerve-activating stimulation technology require multi-scale detail that includes: gross anatomy; skull foramina and superficial tissue layers; and precise nerve morphology. Detailed simulations also predict that some non-invasive electrical or magnetic stimulation approaches that do not intend to modulate cranial nerves per se, such as transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS), may also modulate activity of specific cranial nerves. Much prior cranial nerve stimulation work was conceptually limited to the production of sensory perception, with individual titration of intensity based on the level of perception and tolerability. However, disregarding sensory emulation allows consideration of temporal stimulation patterns (axon recruitment) that modulate the tone of cortical networks independent of sensory cortices, without necessarily titrating perception. For example, leveraging the role of the thalamus as a gatekeeper for information to the cerebral cortex, preventing or enhancing the passage of specific information depending on the behavioral state. We show that properly parameterized computational models at multiple scales are needed to rationally optimize neuromodulation that target sets of cranial nerves, determining which and how specific brain circuitries are modulated, which can in turn influence cognition in a designed manner.
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Affiliation(s)
- Devin Adair
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Dennis Truong
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Zeinab Esmaeilpour
- Department of Biomedical Engineering, City College of New York, New York, NY, USA.
| | - Nigel Gebodh
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Helen Borges
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Libby Ho
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - J Douglas Bremner
- Department of Psychiatry & Behavioral Sciences and Radiology, Emory University School of Medicine, Atlanta, GA, USA; Atlanta VA Medical Center, Decatur, GA, USA
| | - Bashar W Badran
- Department of Psychiatry & Behavioral Sciences, Medical University of South Carolina, Charleston, SC, USA
| | - Vitaly Napadow
- Martinos Center for Biomedical Imaging, Department of Radiology, MGH, Harvard medical school, Boston, MA, USA
| | - Vincent P Clark
- Psychology Clinical Neuroscience Center, Dept. Psychology, MSC03-2220, University of New Mexico, Albuquerque, NM, 87131, USA; Department of Psychology, University of New Mexico, Albuquerque, NM, 87131, USA; The Mind Research Network of the Lovelace Biomedical Research Institute, 1101 Yale Blvd. NE, Albuquerque, NM, 87106, USA
| | - Marom Bikson
- Department of Biomedical Engineering, City College of New York, New York, NY, USA.
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Enayati S, Chang K, Achour H, Cho KS, Xu F, Guo S, Z. Enayati K, Xie J, Zhao E, Turunen T, Sehic A, Lu L, Utheim TP, Chen DF. Electrical Stimulation Induces Retinal Müller Cell Proliferation and Their Progenitor Cell Potential. Cells 2020; 9:E781. [PMID: 32210151 PMCID: PMC7140850 DOI: 10.3390/cells9030781] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 03/12/2020] [Accepted: 03/17/2020] [Indexed: 12/18/2022] Open
Abstract
Non-invasive electrical stimulation (ES) is increasingly applied to improve vision in untreatable eye conditions, such as retinitis pigmentosa and age-related macular degeneration. Our previous study suggested that ES promoted retinal function and the proliferation of progenitor-like glial cells in mice with inherited photoreceptor degeneration; however, the underlying mechanism remains obscure. Müller cells (MCs) are thought to be dormant residential progenitor cells that possess a high potential for retinal neuron repair and functional plasticity. Here, we showed that ES with a ramp waveform of 20 Hz and 300 µA of current was effective at inducing mouse MC proliferation and enhancing their expression of progenitor cell markers, such as Crx (cone-rod homeobox) and Wnt7, as well as their production of trophic factors, including ciliary neurotrophic factor. RNA sequencing revealed that calcium signaling pathway activation was a key event, with a false discovery rate of 5.33 × 10-8 (p = 1.78 × 10-10) in ES-mediated gene profiling changes. Moreover, the calcium channel blocker, nifedipine, abolished the observed effects of ES on MC proliferation and progenitor cell gene induction, supporting a central role of ES-induced Ca2+ signaling in the MC changes. Our results suggest that low-current ES may present a convenient tool for manipulating MC behavior toward neuroregeneration and repair.
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Affiliation(s)
- Sam Enayati
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA; (S.E.); (K.C.); (H.A.); (K.-S.C.); (S.G.); (K.Z.E.); (J.X.); (E.Z.); (T.T.); (T.P.U.)
- Department of Medical Biochemistry, Oslo University Hospital, 0372 Oslo, Norway
- Department of Ophthalmology, Drammen Hospital, Vestre Viken Hospital Trust, 3004 Drammen, Norway
- Institute of clinical medicine, University of Oslo, 0318 Oslo, Norway
| | - Karen Chang
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA; (S.E.); (K.C.); (H.A.); (K.-S.C.); (S.G.); (K.Z.E.); (J.X.); (E.Z.); (T.T.); (T.P.U.)
| | - Hamida Achour
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA; (S.E.); (K.C.); (H.A.); (K.-S.C.); (S.G.); (K.Z.E.); (J.X.); (E.Z.); (T.T.); (T.P.U.)
- Institute of clinical medicine, University of Oslo, 0318 Oslo, Norway
| | - Kin-Sang Cho
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA; (S.E.); (K.C.); (H.A.); (K.-S.C.); (S.G.); (K.Z.E.); (J.X.); (E.Z.); (T.T.); (T.P.U.)
| | - Fuyi Xu
- Department of Genetics, Genomics and Informatics, University of Tennessee Health Science Center, Memphis, TN 38163, USA; (F.X.); (L.L.)
| | - Shuai Guo
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA; (S.E.); (K.C.); (H.A.); (K.-S.C.); (S.G.); (K.Z.E.); (J.X.); (E.Z.); (T.T.); (T.P.U.)
| | - Katarina Z. Enayati
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA; (S.E.); (K.C.); (H.A.); (K.-S.C.); (S.G.); (K.Z.E.); (J.X.); (E.Z.); (T.T.); (T.P.U.)
| | - Jia Xie
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA; (S.E.); (K.C.); (H.A.); (K.-S.C.); (S.G.); (K.Z.E.); (J.X.); (E.Z.); (T.T.); (T.P.U.)
| | - Eric Zhao
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA; (S.E.); (K.C.); (H.A.); (K.-S.C.); (S.G.); (K.Z.E.); (J.X.); (E.Z.); (T.T.); (T.P.U.)
| | - Tytteli Turunen
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA; (S.E.); (K.C.); (H.A.); (K.-S.C.); (S.G.); (K.Z.E.); (J.X.); (E.Z.); (T.T.); (T.P.U.)
| | - Amer Sehic
- Department of Oral Biology; Faculty of Dentistry, University of Oslo, 0372 Oslo, Norway;
| | - Lu Lu
- Department of Genetics, Genomics and Informatics, University of Tennessee Health Science Center, Memphis, TN 38163, USA; (F.X.); (L.L.)
| | - Tor Paaske Utheim
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA; (S.E.); (K.C.); (H.A.); (K.-S.C.); (S.G.); (K.Z.E.); (J.X.); (E.Z.); (T.T.); (T.P.U.)
- Department of Medical Biochemistry, Oslo University Hospital, 0372 Oslo, Norway
- Department of Ophthalmology, Drammen Hospital, Vestre Viken Hospital Trust, 3004 Drammen, Norway
- Department of Oral Biology; Faculty of Dentistry, University of Oslo, 0372 Oslo, Norway;
- Department of Plastic and Reconstructive Surgery, Oslo University Hospital, 0027 Oslo, Norway
| | - Dong Feng Chen
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA; (S.E.); (K.C.); (H.A.); (K.-S.C.); (S.G.); (K.Z.E.); (J.X.); (E.Z.); (T.T.); (T.P.U.)
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7
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Nezakati T, Seifalian A, Tan A, Seifalian AM. Conductive Polymers: Opportunities and Challenges in Biomedical Applications. Chem Rev 2018; 118:6766-6843. [DOI: 10.1021/acs.chemrev.6b00275] [Citation(s) in RCA: 354] [Impact Index Per Article: 59.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Toktam Nezakati
- Google Inc.., Mountain View, California 94043, United States
- Centre for Nanotechnology and Regenerative Medicine, Division of Surgery and Interventional Science, University College London, London NW3 2QG, United Kingdom
| | - Amelia Seifalian
- UCL Medical School, University College London, London WC1E 6BT, United Kingdom
| | - Aaron Tan
- UCL Medical School, University College London, London WC1E 6BT, United Kingdom
| | - Alexander M. Seifalian
- NanoRegMed Ltd. (Nanotechnology and Regenerative Medicine Commercialization Centre), The London Innovation BioScience Centre, London NW1 0NH, United Kingdom
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Yin H, Yin H, Zhang W, Miao Q, Qin Z, Guo S, Fu Q, Ma J, Wu F, Yin J, Yang Y, Fang X. Transcorneal electrical stimulation promotes survival of retinal ganglion cells after optic nerve transection in rats accompanied by reduced microglial activation and TNF-α expression. Brain Res 2016; 1650:10-20. [PMID: 27569587 DOI: 10.1016/j.brainres.2016.08.034] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Revised: 08/20/2016] [Accepted: 08/24/2016] [Indexed: 11/26/2022]
Abstract
Microglial activation plays a crucial role in the pathological processes of various retinal and optic nerve diseases. TNF-α is a pro-inflammatory cytokine that is rapidly upregulated and promotes retinal ganglion cells (RGCs) death after optic nerve injury. However, the cellular source of TNF-α after optic nerve injury remains unclear. Thus, we aimed to determine the changes of retinal microglial activation in a rat model of optic nerve transection (ONT) after transcorneal electrical stimulation (TES). Furthermore, we assessed TNF-α expression after ONT and evaluated the effects of TES on TNF-α production. Rats were divided into 2 control groups receiving a sham surgery procedure, 2 ONT+Sham TES groups, and 2 ONT+TES groups. The rats were sacrificed on day 7 or 14 after ONT. RGCs were retrogradely labelled by Fluorogold (FG) 7 days before ONT, one TES group and corresponding controls were stimulated on day 0, 4, and the second were stimulated on day 0, 4, 7, 10. Whole-mount immunohistofluorescence, quantification of RGCs and microglia, and western blot analysis were performed on day 7 and 14 after ONT. TES significantly increased RGCs survival on day 7 and 14 after ONT, which was accompanied by reduced microglia on day 7, but not 14. TNF-α was co-localized with ameboid microglia and significantly increased on day 7 and 14 after ONT. TES significantly reduced TNF-α production on day 7 and 14 after ONT. Our study demonstrated that TES promotes RGCs survival after ONT accompanied by reduced microglial activation and microglia-derived TNF-α production.
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Affiliation(s)
- Houmin Yin
- Department of Neurology, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, China
| | - Houfa Yin
- Eye Center, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, China; Zhejiang Provincial Key Laboratory of Ophthalmology, Hangzhou, Zhejiang Province, China
| | - Wei Zhang
- Department of Orthopedics, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, China
| | - Qi Miao
- Eye Center, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, China; Zhejiang Provincial Key Laboratory of Ophthalmology, Hangzhou, Zhejiang Province, China
| | - Zhenwei Qin
- Eye Center, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, China; Zhejiang Provincial Key Laboratory of Ophthalmology, Hangzhou, Zhejiang Province, China
| | - Shenchao Guo
- Eye Center, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, China; Zhejiang Provincial Key Laboratory of Ophthalmology, Hangzhou, Zhejiang Province, China
| | - Qiuli Fu
- Eye Center, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, China; Zhejiang Provincial Key Laboratory of Ophthalmology, Hangzhou, Zhejiang Province, China
| | - Jian Ma
- Eye Center, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, China; Zhejiang Provincial Key Laboratory of Ophthalmology, Hangzhou, Zhejiang Province, China
| | - Fang Wu
- Eye Center, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, China; Zhejiang Provincial Key Laboratory of Ophthalmology, Hangzhou, Zhejiang Province, China
| | - Jinfu Yin
- Eye Center, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, China; Zhejiang Provincial Key Laboratory of Ophthalmology, Hangzhou, Zhejiang Province, China
| | - Yabo Yang
- Eye Center, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, China; Zhejiang Provincial Key Laboratory of Ophthalmology, Hangzhou, Zhejiang Province, China
| | - Xiaoyun Fang
- Eye Center, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, China; Zhejiang Provincial Key Laboratory of Ophthalmology, Hangzhou, Zhejiang Province, China.
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9
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Feng Z, Du Q. Mechanisms responsible for the effect of median nerve electrical stimulation on traumatic brain injury-induced coma: orexin-A-mediated N-methyl-D-aspartate receptor subunit NR1 upregulation. Neural Regen Res 2016; 11:951-6. [PMID: 27482224 PMCID: PMC4962593 DOI: 10.4103/1673-5374.184494] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Electrical stimulation of the median nerve is a noninvasive technique that facilitates awakening from coma. In rats with traumatic brain injury-induced coma, median nerve stimulation markedly enhances prefrontal cortex expression of orexin-A and its receptor, orexin receptor 1. To further understand the mechanism underlying wakefulness mediated by electrical stimulation of the median nerve, we evaluated its effects on the expression of the N-methyl-D-aspartate receptor subunit NR1 in the prefrontal cortex in rat models of traumatic brain injury-induced coma, using immunohistochemistry and western blot assays. In rats with traumatic brain injury, NR1 expression increased with time after injury. Rats that underwent electrical stimulation of the median nerve (30 Hz, 0.5 ms, 1.0 mA for 15 minutes) showed elevated NR1 expression and greater recovery of consciousness than those without stimulation. These effects were reduced by intracerebroventricular injection of the orexin receptor 1 antagonist SB334867. Our results indicate that electrical stimulation of the median nerve promotes recovery from traumatic brain injury-induced coma by increasing prefrontal cortex NR1 expression via an orexin-A-mediated pathway.
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Affiliation(s)
- Zhen Feng
- Department of Rehabilitation, the First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province, China
| | - Qing Du
- Department of Rehabilitation, the First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province, China
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Feng Z, Zhong YJ, Wang L, Wei TQ. Resuscitation therapy for traumatic brain injury-induced coma in rats: mechanisms of median nerve electrical stimulation. Neural Regen Res 2015; 10:594-8. [PMID: 26170820 PMCID: PMC4424752 DOI: 10.4103/1673-5374.155433] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2014] [Indexed: 11/30/2022] Open
Abstract
In this study, rats were put into traumatic brain injury-induced coma and treated with median nerve electrical stimulation. We explored the wake-promoting effect, and possible mechanisms, of median nerve electrical stimulation. Electrical stimulation upregulated the expression levels of orexin-A and its receptor OX1R in the rat prefrontal cortex. Orexin-A expression gradually increased with increasing stimulation, while OX1R expression reached a peak at 12 hours and then decreased. In addition, after the OX1R antagonist, SB334867, was injected into the brain of rats after traumatic brain injury, fewer rats were restored to consciousness, and orexin-A and OXIR expression in the prefrontal cortex was downregulated. Our findings indicate that median nerve electrical stimulation induced an up-regulation of orexin-A and OX1R expression in the prefrontal cortex of traumatic brain injury-induced coma rats, which may be a potential mechanism involved in the wake-promoting effects of median nerve electrical stimulation.
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Affiliation(s)
- Zhen Feng
- Department of Rehabilitation Medicine, the First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province, China
| | - Ying-Jun Zhong
- Department of Rehabilitation Medicine, the First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province, China
| | - Liang Wang
- Department of Rehabilitation Medicine, the First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province, China
| | - Tian-Qi Wei
- Department of Rehabilitation Medicine, the First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province, China
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Zhu N, Zhang C, Li Z, Meng Y, Feng B, Wang X, Yang M, Wan L, Ning B, Li S. Experimental study on the effect of electrostimulation on neural regeneration after oculomotor nerve injury. J Mol Neurosci 2014; 54:639-52. [PMID: 25022883 DOI: 10.1007/s12031-014-0358-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Accepted: 06/19/2014] [Indexed: 11/25/2022]
Abstract
The oculomotor nerve can regenerate anatomically and histologically after injury; however, the degree of functional recovery of extraocular muscles and the pupil sphincter muscle was not satisfactory. Electrostimulation was one potential intervention that was increasingly being studied for use in nerve injury settings. However, the effect of electrostimulation on regeneration of the injured oculomotor nerve was still obscure. In this study, we studied the effects of electrostimulation on neural regeneration in terms of neurofunction, myoelectrophysiology, neuroanatomy, and neurohistology after oculomotor nerve injury and found that electrostimulation on the injured oculomotor nerve enhanced the speed and final level of its functional and electrophysiological recovery, promoted neural regeneration, and enhanced the selectivity and specificity of reinnervation of the regenerated neuron, the conformity among the electrophysiological and functional recovery of extraocular muscles, and neural regeneration, and that the function of extraocular muscles recovered slower than electrophysiology. Thus, we speculated that electrostimulation on the injured oculomotor nerve produced a marked effect on all phases of neural regeneration including neuronal survival, sprout formation, axonal elongation, target reconnection, and synaptogenesis. We think that neural electrostimulation can be used in oculomotor nerve injury.
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Affiliation(s)
- Ningxi Zhu
- Department of Neurosurgery, The Central Hospital of Tai'an, No. 29 Longtan Road, 271000, Tai'an, China,
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Fransen JW, Pangeni G, Pardue MT, McCall MA. Local signaling from a retinal prosthetic in a rodent retinitis pigmentosa model in vivo. J Neural Eng 2014; 11:046012. [PMID: 24940618 DOI: 10.1088/1741-2560/11/4/046012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE In clinical trials, retinitis pigmentosa patients implanted with a retinal prosthetic device show enhanced spatial vision, including the ability to read large text and navigate. New prosthetics aim to increase spatial resolution by decreasing pixel/electrode size and limiting current spread. To examine spatial resolution of a new prosthetic design, we characterized and compared two photovoltaic array (PVA) designs and their interaction with the retina after subretinal implantation in transgenic S334ter line 3 rats (Tg S334ter-3). APPROACH PVAs were implanted subretinally at two stages of degeneration and assessed in vivo using extracellular recordings in the superior colliculus (SC). Several aspects of this interaction were evaluated by varying duration, irradiance and position of a near infrared laser focused on the PVA. These characteristics included: activation threshold, response linearity, SC signal topography and spatial localization. The major design difference between the two PVA designs is the inclusion of local current returns in the newer design. MAIN RESULTS When tested in vivo, PVA-evoked response thresholds were independent of pixel/electrode size, but differ between the new and old PVA designs. Response thresholds were independent of implantation age and duration (⩽7.5 months). For both prosthesis designs, threshold intensities were within established safety limits. PVA-evoked responses require inner retina synaptic transmission and do not directly activate retinal ganglion cells. The new PVA design evokes local retinal activation, which is not found with the older PVA design that lacks local current returns. SIGNIFICANCE Our study provides in vivo evidence that prosthetics make functional contacts with the inner nuclear layer at several stages of degeneration. The new PVA design enhances local activation within the retina and SC. Together these results predict that the new design can potentially harness the inherent processing within the retina and is likely to produce higher spatial resolution in patients.
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Affiliation(s)
- James W Fransen
- Department of Anatomical Sciences and Neurobiology, University of Louisville, KY 40202, USA
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Ou YT, Lu MSC, Chiao CC. The effects of electrical stimulation on neurite outgrowth of goldfish retinal explants. Brain Res 2012; 1480:22-9. [DOI: 10.1016/j.brainres.2012.08.041] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 07/31/2012] [Accepted: 08/23/2012] [Indexed: 10/28/2022]
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Liu Y, Tang L, Chen B. Effects of antioxidant gene therapy on retinal neurons and oxidative stress in a model of retinal ischemia/reperfusion. Free Radic Biol Med 2012; 52:909-15. [PMID: 22240151 DOI: 10.1016/j.freeradbiomed.2011.12.013] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 12/08/2011] [Accepted: 12/14/2011] [Indexed: 11/16/2022]
Abstract
Retinal ischemia/reperfusion (I/R) results in neuronal death and generation of reactive oxygen species. The aim of this study was to investigate the neuroprotective effect of manganese superoxide dismutase (SOD2) on retinal ganglion cells (RGCs) in an I/R-induced retinal injury model. One eye of each Wistar rat was pretreated with recombinant adeno-associated virus containing the SOD2 gene (AAV-SOD2) or recombinant AAV containing the GFP gene (AAV-GFP) by intravitreal injection 21 days before initiation of I/R injury. Retinal I/R injury was induced by elevating intraocular pressure for 1h, and reperfusion was established immediately afterward. The number of RGCs and the inner plexiform layer (IPL) thickness were measured by Fluorogold retrograde labeling and hematoxylin and eosin staining at 6 h, 24 h, 72 h, and 5 days after injury. Superoxide anion, the number of RGCs, IPL thickness, malondialdehyde (MDA) level, 8-hydroxy-2-deoxyguanosine (8-OHdG) level, MnSOD (manganese superoxide dismutase) activity, and nitrotyrosine level were measured by fluorescence staining, immunohistochemistry, and enzyme-linked immunosorbent analysis at 5 days after I/R injury. Severe RGC loss, reduced IPL thickness, reduced MnSOD activity, and increased superoxide ion, MDA, 8-OHdG, and nitrotyrosine production were observed after I/R injury. Administration of AAV-SOD2 significantly reduced the levels of superoxide ion, MDA, 8-OHdG, and nitrotyrosine and prevented the damage to RGCs and IPL. Delivery of the antioxidant gene inhibited I/R-induced RGC and IPL damage by reducing oxidative stress and nitrative stress, suggesting that MnSOD may be relevant for the neuroprotection of the inner retina from I/R-related diseases.
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Affiliation(s)
- Yu Liu
- Department of Ophthalmology, Second Xiangya Hospital, Central South University, Changsha, Hunan Province, People's Republic of China
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Gekeler F, Bartz-Schmidt KU. Electrical stimulation--a therapeutic strategy for retinal and optic nerve disease? Graefes Arch Clin Exp Ophthalmol 2012; 250:161-3. [PMID: 22282217 DOI: 10.1007/s00417-012-1930-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 01/10/2012] [Indexed: 11/25/2022] Open
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Abstract
Neurons of the central nervous system (CNS) of adult mammals can be damaged in a variety of ways. Most neurons rapidly die after injury. Even if the injured CNS neurons do not die in a short time, the neurons eventually die because they are not able to regenerate their axons to reconnect with their normal targets. In addition, neurons are normally not replaced. Therefore, much work has been directed toward understanding of the molecular regulation of the CNS degeneration following injury, and different experimental strategies are being used to try to protect the damaged neurons. Following axonal lesion, the neurons not only need to survive but also to reconnect to be functionally relevant, and efforts are directed toward not only survival but also axonal regeneration and proper rewiring of injured neurons. Recent experimental data suggest that electrical activity, endogenous or exogenous, can enhance neuronal survival and regeneration in vitro and in vivo. This chapter reviews the evidence that have been obtained on the role of neuronal electrical activity on neuroprotection. We will develop perspectives toward neuroprotection and regeneration of adult lesioned CNS neurons based on electrical activity-dependent cell survival that may be applicable to various diseases of the CNS.
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Chen B, Tang L. Protective effects of catalase on retinal ischemia/reperfusion injury in rats. Exp Eye Res 2011; 93:599-606. [PMID: 21824472 DOI: 10.1016/j.exer.2011.07.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Revised: 07/01/2011] [Accepted: 07/20/2011] [Indexed: 10/18/2022]
Abstract
Retinal ischemia/reperfusion (I/R) injury causes profound tissue damage, especially retinal ganglion cell (RGC) death. The aims of the study were to investigate whether catalase (CAT) has a neuroprotective effect on RGC after I/R injury in rats, and to determine the possible antioxidant mechanism. Wistar female rats were randonmized into four groups: normal control group (Control group), retinal I/R with vehicle group (I/R with vehicle group), retinal I/R with AAV-CAT group (I/R with AAV-CAT group), and normal retina with AAV-CAT group (normal with AAV-CAT group). One eye of each rat was pretreated with recombinant adeno-associated virus containing catalase gene (I/R with AAV-CAT group or normal with AAV-CAT group) and recombinant adeno-associated virus containing GFP gene (I/R with vehicle group) by intravitreal injection 21 days before initiation of I/R injury. Retinal I/R injury was induced by elevating intraocular pressure to 100mmHg for 1h. The number of RGC and inner plexiform layer (IPL) thickness were measured by fluorogold retrograde labeling and hematoxylin and eosin staining at 6h, 24h, 72 h and 5d after injury. Hydrogen peroxide (H(2)O(2)), the number of RGC, IPL thickness, malondialdehyde(MDA), 8-hydroxy-2-deoxyguanosine (8-OHdG), CAT activity and nitrotyrosine were measured by fluorescence staining, immunohistochemistry and enzyme-linked immunosorbent assay analysis at 5 days after injury. Electroretinographic (ERG) evaluation was also used. Pretreatment of AAV-CAT significantly decreased the levels of H(2)O(2), MDA, 8-OHdG and nitrotyrosine, increased the catalase activity, and prevented the reduction of a- and b- waves in the I/R with AAV-CAT group compare with the I/R with vehicle group (p<0.01). Catalase attenuated the I/R-induced damage of RGC and IPL and retinal function. Therefore, catalase can protect the rat retina from I/R-induced injury by enhancing the antioxidative ability and reducing oxidative stress, which suggests that catalase may be relevant for the neuroprotection of inner retina from I/R-related diseases.
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Affiliation(s)
- Baihua Chen
- Department of Ophthalmology, Second Xiangya Hospital, Central South University, 139 Renming Middle Road, Changsha Hunan Province 410011, PR China
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Electrical stimulation and testosterone differentially enhance expression of regeneration-associated genes. Exp Neurol 2010; 223:183-91. [DOI: 10.1016/j.expneurol.2009.04.031] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Revised: 04/26/2009] [Accepted: 04/28/2009] [Indexed: 02/04/2023]
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Optimal parameters of transcorneal electrical stimulation (TES) to be neuroprotective of axotomized RGCs in adult rats. Exp Eye Res 2010; 90:285-91. [PMID: 19909741 DOI: 10.1016/j.exer.2009.11.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Revised: 10/27/2009] [Accepted: 11/03/2009] [Indexed: 11/23/2022]
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Corredor RG, Goldberg JL. Electrical activity enhances neuronal survival and regeneration. J Neural Eng 2009; 6:055001. [DOI: 10.1088/1741-2560/6/5/055001] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Ni YQ, Gan DK, Xu HD, Xu GZ, Da CD. Neuroprotective effect of transcorneal electrical stimulation on light-induced photoreceptor degeneration. Exp Neurol 2009; 219:439-52. [PMID: 19576889 DOI: 10.1016/j.expneurol.2009.06.016] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2009] [Revised: 06/17/2009] [Accepted: 06/20/2009] [Indexed: 10/20/2022]
Abstract
Direct electrical stimulation of neural tissues is a strategic approach to treat injured axons by accelerating their outgrowth [Al-Majed, A.A., Neumann, C.M., Brushart, T.M., Gordon, T., 2000. Brief electrical stimulation promotes the speed and accuracy of motor axonal regeneration. J. Neurosci. 20, 2602-2608] and promoting their regeneration [Geremia, N.M., Gordon, T., Brushart, T.M., Al-Majed, A.A., Verge, V.M.K., 2007. Electrical stimulation promotes sensory neuron regeneration and growth-associated gene expression. Exp. Neurol. 205, 347-359]. Recently, transcorneal electrical stimulation (TCES), a novel less invasive method, has been shown to rescue axotomized and damaged retinal ganglion cells [Morimoto, T., Miyoshi, T., Matsuda, S., Tano, Y., Fujikado, T., Fukuda, Y., 2005. Transcorneal electrical stimulation rescues axotomized retinal ganglion cells by activating endogenous retinal IGF-1 system. Invest. Ophthalmol. Vis. Sci. 46(6), 2147-2155]. Here, we investigated the neuroprotection of TCES on light-induced photoreceptor degeneration and the underlying mechanism. Adult male Sprague-Dawley (SD) rats received TCES before (pre-TCES) or after (post-TCES) intense light exposure. After fourteen days of light exposure, retinal histology and electroretinography were performed to evaluate the neuroprotective effect of TCES. The mRNA and protein levels of apoptotic-associated genes including Bcl-2, Bax, Caspase-3 as well as ciliary neurotrophic factor (CNTF) and brain-derived neurotrophic factor (BDNF) in the retinas were determined by real-time PCR and Western blot analysis. The localization of these gene products in the retinas was examined by immunohistochemistry. Both pre- and post-TCES ameliorated the progressive photoreceptor degeneration. The degree of rescue depended on the strength of the electric charge. Post-TCES showed a relatively better and longer-term protective effect than pre-TCES. Real-time PCR and Western blot analysis revealed an upregulation of Bcl-2, CNTF, and BDNF and a downregulation of Bax in the retinas after TCES. Immunohistochemical studies showed that Bcl-2 and CNTF were selectively upregulated in Müller cells. These findings provide a new therapeutic method to prevent or delay photoreceptor degeneration through activating the intrinsic survival system.
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Affiliation(s)
- Ying-qin Ni
- Department of Ophthalmology, Eye and ENT Hospital of Fudan University, 83 Fen Yang Road, Shanghai 200031, People's Republic of China
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Axonal regeneration induced by repetitive electrical stimulation of crushed optic nerve in adult rats. Jpn J Ophthalmol 2009; 53:257-66. [PMID: 19484445 DOI: 10.1007/s10384-009-0657-8] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Accepted: 01/30/2009] [Indexed: 10/20/2022]
Abstract
PURPOSE To investigate whether electrical stimulation promoted axonal regeneration of retinal ganglion cells (RGCs) after optic nerve (ON) crush in adult rats. METHODS Transcorneal electrical stimulation (TES), which stimulates the retina with current from a corneal contact lens electrode, was used to stimulate the eye. TES was applied for 1 h immediately after ON crush. Axonal regeneration was determined by anterograde labeling of RGC axons. To examine whether the axonal regeneration was mediated by insulin-like growth factor 1 (IGF-1) receptors, an IGF-1 receptor antagonist, JB3, was injected intraperitoneally before each TES application. Immunostaining for IGF-1 was performed to examine the effects of TES. To test the survival-promoting effects of TES applied daily, the mean density of retrogradely labeled RGCs was determined on day 12 after ON crush. RESULTS Compared with sham stimulation, the mean number of regenerating axons significantly increased at 250 microm distal from the lesion and increased IGF-1 immunoreactivity was observed in retinas treated daily with TES. Preinjection of an IGF-1 receptor antagonist significantly blocked axonal regeneration by TES applied daily. TES applied daily also markedly enhanced the survival of RGCs 12 days after ON crush. CONCLUSION TES applied daily promotes both axonal regeneration and survival of RGCs after ON crush.
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