Morphoquantitative and molecular aspects of skeletal muscle of rats submitted to treatment with insulin after burn injury

Abstract

Extensive burn injury has been associated with children who have suffered scald injury. This lesion leads to widespread loss of muscle mass. The muscle loss is associated with hypermetabolism, systemic inflammation, hyperglycemia and insulin resistance. Skeletal muscle of rats submitted to burn injury has increased inflammatory activity, increased immunoreactivity of myogenic regulatory factors (MyoD and myogenin) and altered genes related to muscle atrophy. The aim of this study is to evaluate the effects of daily treatment with insulin in skeletal muscle (gastrocnemius) of young rats after extensive burn injury. This research project was approved by the Ethics Committee in the Animal Use of Federal University of São Paulo (UNIFESP-CEUA) under the number: 4857080514. A total of 48 male Wistar rats will be randomly divided into two groups: Control (C), submitted to scald burn injury (SB) and submitted to scald burn injury with daily insulin treatment (SB+I). Post injury, the body surface, blood glucose as well as ingest and body weight of the animals will be monitored. After euthanasia, the gastrocnemius muscle (characterized for mixed muscle fibers) will be removed for histopathological, morphoquantitative and immunohistochemistry (MyoD, myogenin and satellite cells) analysis. Furthermore, gene expression (qPCR) related to inflammation (iNOS and TNF-alpha), muscular atrophy (MuRF1 and MAFbx) and insulin-like growth factor (IGF-I) will be analyzed. The hypothesis of this study is: the morphology of the skeletal muscle as well as factors related to inflammation, myogenesis and muscle atrophy can be positively affected by administration of insulin after burn injury. The understanding of the mechanisms investigated, will be contribute to the establishment of effective strategies in the rehabilitation of muscle wasting in patients with this condition. (AU)