Role of nitric oxide and nitric oxide synthases in experimental models of denervation and reinnervation
Article first published online: 17 OCT 2001
Copyright © 2001 Wiley-Liss, Inc.
Microscopy Research and Technique
Special Issue: Functional Cytology of Nitric Acid in Striated Muscle—Part I
Volume 55, Issue 3, pages 181–186, 1 November 2001
How to Cite
Tews, D. S. (2001), Role of nitric oxide and nitric oxide synthases in experimental models of denervation and reinnervation. Microsc. Res. Tech., 55: 181–186. doi: 10.1002/jemt.1169
- Issue published online: 17 OCT 2001
- Article first published online: 17 OCT 2001
- Manuscript Accepted: 13 MAR 2001
- Manuscript Received: 9 MAR 2001
- muscle fiber;
Nitric oxide (NO) is a short-living free molecule synthesized by three different isoforms of nitric oxide synthases (NOS)—neuronal NOS, endothelial NOS, and inducible NOS—associated with neuromuscular transmission, muscle contractility, mitochondrial respiration, and carbohydrate metabolism in skeletal muscle. Neuronal NOS is constitutively expressed at the muscle fiber sarcolemma linked to the dystrophin-glycoprotein complex and concentrated at the neuromuscular endplate. There is increasing evidence that altered expression of neuronal NOS plays a role in muscle fiber damage in neuromuscular diseases such as dystrophinopathies and denervating disorders. Although there have been some previous conflicting results on the neuronal NOS expression pattern in denervated muscle fibers, it is now well established that denervation is associated with a down-regulation and disappearance of sarcolemmal neuronal NOS at synaptic/extrasynaptic or both sites. As NO has been shown to induce collapse and growth arrest on neuronal growth cones, down-regulation of sarcolemmal neuronal NOS may contribute to axonal regeneration and attraction to muscle fibers aiming at the formation of new motor endplates providing reinnervation and reconstitution of NOS expression. As NO serves as a retrograde messenger, it may trigger structural downstream events responsible for neuromuscular synaptogenesis and preventing polyneural innervation. Nevertheless, decreased NO production in denervation reduces the cytoprotective scavenger function of NO for superoxide anions promoting oxidative stress that is likely to be involved in muscle fiber damage and death. However, the multifaced role of NOS and NO under physiological and pathological conditions remains poorly understood on the basis of the current knowledge. Microsc. Res. Tech. 55:181–186, 2001. © 2001 Wiley-Liss, Inc.