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Harrigan ME, Filous AR, Vadala CP, Webb A, Pietrzak M, Sahenk Z, Prüss H, Reiser PJ, Popovich PG, Arnold WD, Schwab JM. Lesion level-dependent systemic muscle wasting after spinal cord injury is mediated by glucocorticoid signaling in mice. Sci Transl Med 2023; 15:eadh2156. [PMID: 38117902 DOI: 10.1126/scitranslmed.adh2156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 11/29/2023] [Indexed: 12/22/2023]
Abstract
An incomplete mechanistic understanding of skeletal muscle wasting early after spinal cord injury (SCI) precludes targeted molecular interventions. Here, we demonstrated systemic wasting that also affected innervated nonparalyzed (supralesional) muscles and emerged within 1 week after experimental SCI in mice. Systemic muscle wasting caused muscle weakness, affected fast type 2 myofibers preferentially, and became exacerbated after high (T3) compared with low (T9) thoracic paraplegia, indicating lesion level-dependent ("neurogenic") mechanisms. The wasting of nonparalyzed muscle and its rapid onset and severity beyond what can be explained by disuse implied unknown systemic drivers. Muscle transcriptome and biochemical analysis revealed a glucocorticoid-mediated catabolic signature early after T3 SCI. SCI-induced systemic muscle wasting was mitigated by (i) endogenous glucocorticoid ablation (adrenalectomy) and (ii) pharmacological glucocorticoid receptor (GR) blockade and was (iii) completely prevented after T3 relative to T9 SCI by genetic muscle-specific GR deletion. These results suggest that neurogenic hypercortisolism contributes to a rapid systemic and functionally relevant muscle wasting syndrome early after paraplegic SCI in mice.
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Affiliation(s)
- Markus E Harrigan
- Department of Neurology, Spinal Cord Injury Division (Paraplegiology), College of Medicine, Ohio State University, Wexner Medical Center, Columbus, OH 43210, USA
- Medical Scientist Training Program, College of Medicine, Ohio State University, Wexner Medical Center, Columbus, OH 43210, USA
- Neuroscience Research Institute, Ohio State University, Columbus, OH 43210, USA
- Belford Center for Spinal Cord Injury, Ohio State University, Wexner Medical Center, Columbus, OH 43210, USA
| | - Angela R Filous
- Department of Neurology, Spinal Cord Injury Division (Paraplegiology), College of Medicine, Ohio State University, Wexner Medical Center, Columbus, OH 43210, USA
- Neuroscience Research Institute, Ohio State University, Columbus, OH 43210, USA
- Belford Center for Spinal Cord Injury, Ohio State University, Wexner Medical Center, Columbus, OH 43210, USA
| | - Christopher P Vadala
- Department of Neurology, Spinal Cord Injury Division (Paraplegiology), College of Medicine, Ohio State University, Wexner Medical Center, Columbus, OH 43210, USA
- Neuroscience Research Institute, Ohio State University, Columbus, OH 43210, USA
- Belford Center for Spinal Cord Injury, Ohio State University, Wexner Medical Center, Columbus, OH 43210, USA
| | - Amy Webb
- Department of Biomedical Informatics, College of Medicine, Ohio State University, Wexner Medical Center, Columbus, OH 43210, USA
| | - Maciej Pietrzak
- Department of Biomedical Informatics, College of Medicine, Ohio State University, Wexner Medical Center, Columbus, OH 43210, USA
| | - Zarife Sahenk
- Center for Gene Therapy, Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA
- Department of Pediatrics and Neurology, Nationwide Children's Hospital and Ohio State University, Columbus, OH 43205, USA
- Department of Pathology and Laboratory Medicine, Nationwide Children's Hospital, Columbus, OH 43205, USA
| | - Harald Prüss
- Department of Neurology and Experimental Neurology, Charité-Universitätsmedizin, 10117 Berlin, Germany
- German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
| | - Peter J Reiser
- Division of Biosciences, College of Dentistry, Ohio State University, Columbus, OH 43210, USA
| | - Phillip G Popovich
- Neuroscience Research Institute, Ohio State University, Columbus, OH 43210, USA
- Belford Center for Spinal Cord Injury, Ohio State University, Wexner Medical Center, Columbus, OH 43210, USA
- Department of Neuroscience, Ohio State University, Wexner Medical Center, Columbus, OH 43210, USA
| | - W David Arnold
- NextGen Precision Health, University of Missouri, Columbia, MO 65211, USA
- Department of Physical Medicine and Rehabilitation, University of Missouri, Columbia, MO 65212, USA
| | - Jan M Schwab
- Department of Neurology, Spinal Cord Injury Division (Paraplegiology), College of Medicine, Ohio State University, Wexner Medical Center, Columbus, OH 43210, USA
- Neuroscience Research Institute, Ohio State University, Columbus, OH 43210, USA
- Belford Center for Spinal Cord Injury, Ohio State University, Wexner Medical Center, Columbus, OH 43210, USA
- Department of Neuroscience, Ohio State University, Wexner Medical Center, Columbus, OH 43210, USA
- Department of Physical Medicine and Rehabilitation, Ohio State University, Wexner Medical Center, Columbus, OH 43210, USA
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In vivo imaging of axonal transport in peripheral nerves of rodent forelimbs. Neuronal Signal 2023; 7:NS20220098. [PMID: 36743438 PMCID: PMC9867938 DOI: 10.1042/ns20220098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 12/23/2022] [Accepted: 01/05/2023] [Indexed: 01/07/2023] Open
Abstract
Axonal transport is the essential process by which neurons actively traffic a variety of cargoes between the cell soma and axon terminals. Accordingly, dysfunctional axonal transport is linked to many nervous system conditions. Therefore, being able to image and quantify this dynamic process in live neurons of animal disease models is beneficial for understanding neuropathology and testing new therapies at the preclinical level. As such, intravital approaches have been developed to assess cargo movement in the hindlimb sciatic nerves of live, anaesthetised mice. Here, we describe an adapted method for in vivo imaging of axonal transport in intact median and ulnar nerves of the rodent forelimb. Injection of a fluorescently labelled and non-toxic fragment of tetanus neurotoxin (HCT) into the mouse forepaw permits the identification of signalling endosomes in intact axons of median and ulnar nerves. Through immunofluorescent analysis of forelimb lumbrical muscles and median/ulnar nerves, we confirmed that HCT is taken up at motor nerve terminals and predominantly locates to motor axons. We then showed that the baseline trafficking of signalling endosomes is similar between the median/ulnar nerves and the sciatic nerve in adult wild-type mice. Importantly, this adapted method can be readily tailored for assessment of additional cargoes, such as mitochondria. By measuring transport in forelimb and hindlimb nerves, comparative anatomical and functional analyses can be performed in rodent disease models to aid our understanding of peripheral nerve disease pathogenesis and response to injury.
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Leermakers PA, Skov M, Riisager A, Nielsen OB, Pedersen TH. Alterations in fast-twitch muscle membrane conductance regulation do not explain decreased muscle function of SOD1 G93A rats. Muscle Nerve 2021; 64:755-764. [PMID: 34486134 DOI: 10.1002/mus.27413] [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: 01/02/2021] [Revised: 08/29/2021] [Accepted: 08/31/2021] [Indexed: 11/06/2022]
Abstract
INTRODUCTION/AIMS Both neuromuscular junction (NMJ) dysfunction and altered electrophysiological properties of muscle fibers have been reported in amyotrophic lateral sclerosis (ALS) patients. ALS-related preclinical studies typically use rodent SOD1G93A overexpression models, but translation to the human disease has been challenged. The present work explored NMJ function and cellular electrophysiological properties of muscles fibers in SOD1G93A overexpression rats. METHODS Longitudinal studies of compound muscle action potentials (CMAPs) were performed in SOD1G93A rats. Cellular studies were performed to evaluate electrophysiological properties of muscle fibers, including the resting membrane conductance (Gm ) and its regulation during prolonged action potential (AP) firing. RESULTS SOD1G93A rats showed a substantial loss of gastrocnemius CMAP amplitude (35.8 mV, P < .001) and a minor increase in CMAP decrement (8.5%, P = .002) at 25 weeks. In addition, SOD1G93A EDL muscle fibers showed a lower baseline Gm (wild-type, 1325 μS/cm2 ; SOD1G93A , 1137 μS/cm2 ; P < .001) and minor alterations in Gm regulation during repeated firing of APs as compared with wild-type rats. DISCUSSION The current data suggest that loss of CMAP amplitude is largely explained by defects in either lower motor neuron or skeletal muscle with only minor indications of a role for neuromuscular transmission defects in SOD1G93A rats. Electrophysiological properties of muscle fibers were not markedly affected, and an elevated Gm , as has been reported in motor neuron disease (MND) patients, was not replicated in SOD1G93A muscles. Collectively, the neuromuscular pathology of SOD1G93A rats appears to differ from that of ALS/MND patients with respect to neuromuscular transmission defects and electrophysiological properties of muscle fibers.
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Affiliation(s)
| | - Martin Skov
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Anders Riisager
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Ole B Nielsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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Padilla CJ, Harrigan ME, Harris H, Schwab JM, Rutkove SB, Rich MM, Clark BC, Arnold WD. Profiling age-related muscle weakness and wasting: neuromuscular junction transmission as a driver of age-related physical decline. GeroScience 2021; 43:1265-1281. [PMID: 33895959 PMCID: PMC8190265 DOI: 10.1007/s11357-021-00369-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 04/19/2021] [Indexed: 12/22/2022] Open
Abstract
Pathological age-related loss of skeletal muscle strength and mass contribute to impaired physical function in older adults. Factors that promote the development of these conditions remain incompletely understood, impeding development of effective and specific diagnostic and therapeutic approaches. Inconclusive evidence across species suggests disruption of action potential signal transmission at the neuromuscular junction (NMJ), the crucial connection between the nervous and muscular systems, as a possible contributor to age-related muscle dysfunction. Here we investigated age-related loss of NMJ function using clinically relevant, electrophysiological measures (single-fiber electromyography (SFEMG) and repetitive nerve stimulation (RNS)) in aged (26 months) versus young (6 months) F344 rats. Measures of muscle function (e.g., grip strength, peak plantarflexion contractility torque) and mass were assessed for correlations with physiological measures (e.g., indices of NMJ transmission). Other outcomes also included plantarflexion muscle contractility tetanic torque fade during 1-s trains of stimulation as well as gastrocnemius motor unit size and number. Profiling NMJ function in aged rats identified significant declines in NMJ transmission stability and reliability. Further, NMJ deficits were tightly correlated with hindlimb grip strength, gastrocnemius muscle weight, loss of peak contractility torque, degree of tetanic fade, and motor unit loss. Thus, these findings provide direct evidence for NMJ dysfunction as a potential mechanism of age-related muscle dysfunction pathogenesis and severity. These findings also suggest that NMJ transmission modulation may serve as a target for therapeutic development for age-related loss of physical function.
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Affiliation(s)
- Carlos J Padilla
- Division of Neuromuscular Diseases, Department of Neurology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Room 207, Columbus, OH, 43210, USA
| | - Markus E Harrigan
- Division of Neuromuscular Diseases, Department of Neurology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Room 207, Columbus, OH, 43210, USA
| | - Hallie Harris
- Division of Neuromuscular Diseases, Department of Neurology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Room 207, Columbus, OH, 43210, USA
| | - Jan M Schwab
- Division of Neuromuscular Diseases, Department of Neurology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Room 207, Columbus, OH, 43210, USA
- Belford Center for Spinal Cord Injury, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- Department of Physical Medicine and Rehabilitation, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- Center for Brain and Spinal Cord Repair, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- The Neurological Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Seward B Rutkove
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Mark M Rich
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH, 45435, USA
| | - Brian C Clark
- Department of Biomedical Sciences, Ohio Musculoskeletal and Neurological Institute, Athens, OH, 45701, USA
| | - W David Arnold
- Division of Neuromuscular Diseases, Department of Neurology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Room 207, Columbus, OH, 43210, USA.
- Department of Physical Medicine and Rehabilitation, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
- The Neurological Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
- Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
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Balch MHH, Harris H, Chugh D, Gnyawali S, Rink C, Nimjee SM, Arnold WD. Ischemic stroke-induced polyaxonal innervation at the neuromuscular junction is attenuated by robot-assisted mechanical therapy. Exp Neurol 2021; 343:113767. [PMID: 34044000 DOI: 10.1016/j.expneurol.2021.113767] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 04/30/2021] [Accepted: 05/22/2021] [Indexed: 01/12/2023]
Abstract
Ischemic stroke is a leading cause of disability world-wide. Mounting evidence supports neuromuscular pathology following stroke, yet mechanisms of dysfunction and therapeutic action remain undefined. The objectives of our study were to investigate neuromuscular pathophysiology following ischemic stroke and to evaluate the therapeutic effect of Robot-Assisted Mechanical massage Therapy (RAMT) on neuromuscular junction (NMJ) morphology. Using an ischemic stroke model in male rats, we demonstrated longitudinal losses of muscle contractility and electrophysiological estimates of motor unit number in paretic hindlimb muscles within 21 days of stroke. Histological characterization demonstrated striking pre- and postsynaptic alterations at the NMJ. Stroke prompted enlargement of motor axon terminals, acetylcholine receptor (AChR) area, and motor endplate size. Paretic muscle AChRs were also more homogenously distributed across motor endplates, exhibiting fewer clusters and less fragmentation. Most interestingly, NMJs in paretic muscle exhibited increased frequency of polyaxonal innervation. This finding of increased polyaxonal innervation in stroke-affected skeletal muscle suggests that reduction of motor unit number following stroke may be a spurious artifact due to overlapping of motor units rather than losses. Furthermore, we tested the effects of RAMT - which we recently showed to improve motor function and protect against subacute myokine disturbance - and found significant attenuation of stroke-induced NMJ alterations. RAMT not only normalized the post-stroke presentation of polyaxonal innervation but also mitigated postsynaptic expansion. These findings confirm complex neuromuscular pathophysiology after stroke, provide mechanistic direction for ongoing research, and inform development of future therapeutic strategies. SIGNIFICANCE: Ischemic stroke is a leading contributor to chronic disability, and there is growing evidence that neuromuscular pathology may contribute to the impact of stroke on physical function. Following ischemic stroke in a rat model, there are progressive declines of motor unit number estimates and muscle contractility. These changes are paralleled by striking pre- and postsynaptic maladaptive changes at the neuromuscular junction, including polyaxonal innervation. When administered to paretic hindlimb muscle, Robot-Assisted Mechanical massage Therapy - previously shown to improve motor function and protect against subacute myokine disturbance - prevents stroke-induced neuromuscular junction alterations. These novel observations provide insight into the neuromuscular response to cerebral ischemia, identify peripheral mechanisms of functional disability, and present a therapeutic rehabilitation strategy with clinical relevance.
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Affiliation(s)
- Maria H H Balch
- Department of Biomedical Education and Anatomy, The Ohio State University College of Medicine, Columbus, OH, USA; Department of Neurosurgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Hallie Harris
- Department of Neurosurgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Deepti Chugh
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Surya Gnyawali
- Department of Neurosurgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Cameron Rink
- Department of Neurosurgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Shahid M Nimjee
- Department of Neurosurgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - W David Arnold
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Physical Medicine and Rehabilitation, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
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