The Preliminary Study Of Apoptosis In Skeletal Muscle At The Early Stage Of Peripheral Never Regeneration In Rats

Objective: To explore the role of apoptosis in skeletal muscle at the early stage of peripheral never regeneration in rats.Methods: Atotal of 54 male Sprague-Duwley rats were randomly assigned to 3 groups (n = 18/group): denervated(A) group, neurorrhaphy group(B), the rats were not treated in group C as control.Under sterile conditions,Denervation was performed by surgically exposing the sciatic nerve in the thigh and then removing a 1-cm-long section of the nerve to prevent reinnervation. In the B group, sciatic nerve was transected 15 mm above its bifurcation and immediately sutured two ends'epineurium refering to its blood vessel. All operating procedure had been operated in the operating microscope.Rats were subjected to 2, 14, 28 days of unilateral denervation or neurorrhaphy of the sciatic.The gastrocnemius were harvested ,weighed muscle-wet weight(GAS) and body mass (BM), gastrocnemius mass served as the degree of muscle atrophy.A search for marker of apoptosis, nuclear DNA fragmentation, using terminal deoxyribonucleotidyl transferase mediated dUTP nick end labeling (the TUNEL method) in situ, then detected in the confocal microscopy. A another portion of gastrocnemius muscle was homogenized and then analysed the activity of caspase-3 and -8 by spectrophotometry.Results: TUNEL labeling of fragmented DNA on histological sections in neuorrhaphy group revealed higher levels of apoptotic nuclei than control ,lower than denervated group's at the earl stage(<28d). The activity of caspase-3 and -8 in posted neuorrhaphy group is also higher than control,lower than denervated group.Conclusion: At the initial stage of peripheral never regeneration, apoptosis may contribute to muscle atrophy and extrinsic apoptotic pathway may takes part in it.