Sarcomere characterization in temporary disused skeletal muscle using second harmonic generation microscopy

Abstract

Temporary skeletal muscle disuse is characterized by muscle proteolysis promoted by the low neuromuscular activity of the patient. In contrast, physical training prevents muscle proteolysis. However, it was reported that during muscle proteolysis the sarcomere's M-band 'a structure of the basic unit of the muscle-, is lengthened. This study presumes that muscle disuse lengthens the M-band, whereas physical activity prevents it. The paralyzed hind limbs from Experimental Autoimmune Encephalomyelitis (EAE) rat model were used to study the effects of muscle disuse and physical training on the sarcomere using the theoretically predicted sarcomeric Second Harmonic Generation (SHG) intensity profile described by Rouède et al. Biophys J. 2011. Our results showed that systemic inflammation is mainly the cause of M-lengthening rather than muscle disuse in EAE rat model. In addition, training significantly lengthens the M-band in EAE rats.