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What is Normal? Neuromuscular junction reinnervation after nerve injury
Author(s) -
Vannucci Bianca,
Santosa Katherine B.,
Keane Alexandra M.,
JablonkaShariff Albina,
Lu ChuiengYi,
Yan Ying,
MacEwan Matthew,
SnyderWarwick Alison K.
Publication year - 2019
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.26654
Subject(s) - reinnervation , neuromuscular junction , denervation , immunostaining , motor endplate , medicine , sciatic nerve , compound muscle action potential , nerve injury , anatomy , electromyography , motor nerve , neuromuscular transmission , motor unit , neuroscience , anesthesia , electrophysiology , biology , immunohistochemistry , physical medicine and rehabilitation
In this study we present a reproducible technique to assess motor recovery after nerve injury via neuromuscular junction (NMJ) immunostaining and electrodiagnostic testing. Methods Wild‐type mice underwent sciatic nerve transection with repair. Hindlimb muscles were collected for microscopy up to 30 weeks after injury. Immunostaining was used to assess axons (NF200), Schwann cells (S100), and motor endplates (α‐bungarotoxin). Compound motor action potential (CMAP) amplitude was used to assess tibialis anterior (TA) function. Results One week after injury, nearly all (98.0%) endplates were denervated. At 8 weeks, endplates were either partially (28.3%) or fully (71.7%) reinnervated. At 16 weeks, NMJ reinnervation reached 87.3%. CMAP amplitude was 83% of naive mice at 16 weeks and correlated with percentage of fully reinnervated NMJs. Morphological differences were noted between injured and noninjured NMJs. Discussion We present a reproducible method for evaluating NMJ reinnervation. Electrodiagnostic data summarize NMJ recovery. Characterization of wild‐type reinnervation provides important data for consideration in experimental design and interpretation.