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Nerve‐terminal and Schwann‐cell response after nerve injury in the absence of nitric oxide
Author(s) -
Marques Maria Julia,
Pereira Elaine Cristina Leite,
Minatel Elaine,
Neto Humberto Santo
Publication year - 2006
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.20576
Subject(s) - schwann cell , lesion , nitric oxide , nerve injury , biology , nitric oxide synthase , motor nerve , neuromuscular junction , neuroscience , microbiology and biotechnology , anatomy , endocrinology , pathology , medicine
Abstract Dystrophic muscles show alterations in the dystrophin–glycoprotein complex and a lack of neuronal nitric oxide (NO) synthase. In mdx mice, presynaptic expression of neuronal NO synthase is decreased, suggesting that presynaptic signaling may be altered in dystrophic muscle. In this study, we examined the nerve‐terminal and Schwann‐cell responses after a crush lesion in control and NO‐deficient mice. Seven days after nerve crush, 24% of control neuromuscular junctions ( n = 200) showed ultraterminal sprouts, whereas in NO‐deficient mice this frequency was 28.5% ( n = 217; P > 0.05 compared to controls; chi‐square test). Schwann‐cell response did not change in the absence of NO, after a nerve lesion of 7‐day duration. Fourteen days after the lesion, nerve terminals sprouted and Schwann cells showed an extensive network of processes away from the synaptic site in controls. In the absence of NO, there was a dramatic decrease in nerve‐terminal sprouting and Schwann‐cell processes failed to extend away from the endplate. These results show that NO is involved in the nerve‐terminal and Schwann‐cell response to nerve injury. They also suggest that presynaptic molecular signaling may be impaired in dystrophic muscles, and this could influence the innervation and survival of newly formed myofibers generated by cell‐mediated therapies. Muscle Nerve, 2006