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Trueblood CT, Singh A, Cusimano MA, Hou S. Autonomic Dysreflexia in Spinal Cord Injury: Mechanisms and Prospective Therapeutic Targets. Neuroscientist 2023:10738584231217455. [PMID: 38084412 PMCID: PMC11166887 DOI: 10.1177/10738584231217455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2024]
Abstract
High-level spinal cord injury (SCI) often results in cardiovascular dysfunction, especially the development of autonomic dysreflexia. This disorder, characterized as an episode of hypertension accompanied by bradycardia in response to visceral or somatic stimuli, causes substantial discomfort and potentially life-threatening symptoms. The neural mechanisms underlying this dysautonomia include a loss of supraspinal control to spinal sympathetic neurons, maladaptive plasticity of sensory inputs and propriospinal interneurons, and excessive discharge of sympathetic preganglionic neurons. While neural control of cardiovascular function is largely disrupted after SCI, the renin-angiotensin system (RAS), which mediates blood pressure through hormonal mechanisms, is up-regulated after injury. Whether the RAS engages in autonomic dysreflexia, however, is still controversial. Regarding therapeutics, transplantation of embryonic presympathetic neurons, collected from the brainstem or more specific raphe regions, into the injured spinal cord may reestablish supraspinal regulation of sympathetic activity for cardiovascular improvement. This treatment reduces the occurrence of spontaneous autonomic dysreflexia and the severity of artificially triggered dysreflexic responses in rodent SCI models. Though transplanting early-stage neurons improves neural regulation of blood pressure, hormonal regulation remains high and baroreflex dysfunction persists. Therefore, cell transplantation combined with selected RAS inhibition may enhance neuroendocrine homeostasis for cardiovascular recovery after SCI.
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Affiliation(s)
- Cameron T. Trueblood
- Marion Murray Spinal Cord Research Center, Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, PA, USA
| | - Anurag Singh
- Marion Murray Spinal Cord Research Center, Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, PA, USA
| | - Marissa A. Cusimano
- Marion Murray Spinal Cord Research Center, Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, PA, USA
| | - Shaoping Hou
- Marion Murray Spinal Cord Research Center, Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, PA, USA
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Strain MM, Johnston DT, Baine RE, Reynolds JA, Huang YJ, Henwood MK, Fauss GN, Davis JA, Miranda RC, West CR, Grau JW. Hemorrhage and Locomotor Deficits Induced by Pain Input after Spinal Cord Injury Are Partially Mediated by Changes in Hemodynamics. J Neurotrauma 2021; 38:3406-3430. [PMID: 34652956 DOI: 10.1089/neu.2021.0219] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Nociceptive input diminishes recovery and increases lesion area after a spinal cord injury (SCI). Recent work has linked these effects to the expansion of hemorrhage at the site of injury. The current article examines whether these adverse effects are linked to a pain-induced rise in blood pressure (BP) and/or flow. Male rats with a low-thoracic SCI were treated with noxious input (electrical stimulation [shock] or capsaicin) soon after injury. Locomotor recovery and BP were assessed throughout. Tissues were collected 3 h, 24 h, or 21 days later. Both electrical stimulation and capsaicin undermined locomotor function and increased the area of hemorrhage. Changes in BP/flow varied depending on type of noxious input, with only shock producing changes in BP. Providing behavioral control over the termination of noxious stimulation attenuated the rise in BP and hemorrhage. Pretreatment with the α-1 adrenergic receptor inverse agonist, prazosin, reduced the stimulation-induced rise in BP and hemorrhage. Prazosin also attenuated the adverse effect that noxious stimulation has on long-term recovery. Administration of the adrenergic agonist, norepinephrine 1 day after injury induced an increase in BP and disrupted locomotor function, but had little effect on hemorrhage. Further, inducing a rise in BP/flow using norepinephrine undermined long-term recovery and increased tissue loss. Mediational analyses suggest that the pain-induced rise in blood flow may foster hemorrhage after SCI. Increased BP appears to act through an independent process to adversely affect locomotor performance, tissue sparing, and long-term recovery.
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Affiliation(s)
- Misty M Strain
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - David T Johnston
- Cellular and Behavioral Neuroscience, Department of Psychology, and College of Medicine, Texas A&M University, College Station, Texas, USA
| | - Rachel E Baine
- Cellular and Behavioral Neuroscience, Department of Psychology, and College of Medicine, Texas A&M University, College Station, Texas, USA
| | - Joshua A Reynolds
- Cellular and Behavioral Neuroscience, Department of Psychology, and College of Medicine, Texas A&M University, College Station, Texas, USA
| | | | - Melissa K Henwood
- Cellular and Behavioral Neuroscience, Department of Psychology, and College of Medicine, Texas A&M University, College Station, Texas, USA
| | - Gizelle N Fauss
- Cellular and Behavioral Neuroscience, Department of Psychology, and College of Medicine, Texas A&M University, College Station, Texas, USA
| | - Jacob A Davis
- Cellular and Behavioral Neuroscience, Department of Psychology, and College of Medicine, Texas A&M University, College Station, Texas, USA
| | - Rajesh C Miranda
- Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University, College Station, Texas, USA
| | - Christopher R West
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - James W Grau
- Cellular and Behavioral Neuroscience, Department of Psychology, and College of Medicine, Texas A&M University, College Station, Texas, USA
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