Cregg JM, Chu KA, Hager LE, Maggard RSJ, Stoltz DR, Edmond M, Alilain WJ, Philippidou P, Landmesser LT, Silver J. A Latent Propriospinal Network Can Restore Diaphragm Function after High Cervical Spinal Cord Injury.
Cell Rep 2017;
21:654-665. [PMID:
29045834 PMCID:
PMC5687843 DOI:
10.1016/j.celrep.2017.09.076]
[Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 08/08/2017] [Accepted: 09/24/2017] [Indexed: 10/18/2022] Open
Abstract
Spinal cord injury (SCI) above cervical level 4 disrupts descending axons from the medulla that innervate phrenic motor neurons, causing permanent paralysis of the diaphragm. Using an ex vivo preparation in neonatal mice, we have identified an excitatory spinal network that can direct phrenic motor bursting in the absence of medullary input. After complete cervical SCI, blockade of fast inhibitory synaptic transmission caused spontaneous, bilaterally coordinated phrenic bursting. Here, spinal cord glutamatergic neurons were both sufficient and necessary for the induction of phrenic bursts. Direct stimulation of phrenic motor neurons was insufficient to evoke burst activity. Transection and pharmacological manipulations showed that this spinal network acts independently of medullary circuits that normally generate inspiration, suggesting a distinct non-respiratory function. We further show that this "latent" network can be harnessed to restore diaphragm function after high cervical SCI in adult mice and rats.
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