Changes of neuronal nitric oxide synthase in skeletal muscles of Duchenne/Becker muscular dystrophies / 中华神经科杂志

ABSTRACT

Objective To study the changes of neuronal nitric oxide synthase in skeletal muscles of Duchenne/Becker muscular dystrophies as to investigaing the pathogenesis of the disease. Methods NADPH diaphorase enzyme histochemistry and nNOS immunohistochemistry were used to analyze the muscle specimens from 36 patients with various muscular dystrophies and 10 normal controls. Results A positive staining was found in sarcolemma of both slow and fast-twitch muscle fibers, in 10 normal controls and 18 patients with non-muscular dystrophy as well as 12 LGMD and 2 FSHD; but a negative staining was found in 10 DMD, and a negative or faint staining in 9 BMD. The loss of nNOS in sarcolemma was associated with the loss of dystrophin, and exon 45～47 in dystrophin gene might be an important region for targeting nNOS to the sarcolemma. The deficiency of nNOS was associated with the severity of DMD/BMD, but no direct evidence for absence of nNOS in sarcolemma leading to the onset of muscle necrosis in DMD/BMD was detected.Conclusions nNOS is expressed at a high level in sarcolemma of normal muscle, and also expressed normally in muscles of those non-muscular dystrophy, LGMD and FSHD patients; but there appear absence or reduction expression in the sarcolemma of DMD and BMD. nNOS is involved in regulating of physiological functions of skeletal muscles and may be an important role in pathogenesis of DMD/BMD.