Thesis (M.Sc.) - Cairo University - Faculty of Medicine - Department of Histology

Nitric oxide (NO) has emerged as a regulator of myogenesis at several steps. This study was designed to evaluate the regulatory role of NO in skeletal muscle healing after crush injury in a rat model, using an inhibitor of NO synthesis NG-nitro-L-arginine-methyl ester (L-NAME) and a NO precursor (L-arginine). 60 rats were used in the study, 30 as control, and 30 were subjected to a crush injury to the right gastrocnemius muscle via mass falling from a height. Then 2 h. post trauma, 10 rats were injected with L-NAME, 10 rats with L-arginine and the remaining 10 rats did not receive any treatment. Histological and immuno-histochemical analysis (for iNOS, MMP-2 and PCNA) were done 24 h post trauma, also Masson{u2019}s trichrome stain to detect collagen 7 days after the trauma. Morphometric study and statistical analysis were done to measure the mean area percent of iNOS and MMP-2 immuno-reactivity, mean number of PCNA +ve cells/HPF, and mean area percent of collagen. It was found that the early changes occurring after the trauma and the degree of fibrosis were greatly dependent on NO, as with L-NAME injection the healing showed thick fibrous scar contrary to L-arginine, which resulted in a thin scar

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