Morphological changes in distant muscle fibers following thermal injury in Wistar rats

Abstract

Purpose: Thermal injury causes catabolic processes as the body attempts to repair the damaged area. This study evaluated the effects of a scald injury on the morphology of muscle fibers belonging to a muscle distant from the lesion. Methods: Thirty Wistar rats were divided into control (C) and scalded (S) groups. Group S was scalded over 45% of the body surface, standardized by body weight. Rats in both groups were euthanized at four, seven and 14 days following the injury. The middle portions of the medial gastrocnemius muscles were sectioned, stained with hematoxylin and eosin and Picrosirius, and submitted to histological analysis. Results: Control group sections exhibited equidistantly distributed polygonal muscle fibers with peripheral nuclei, characteristic of normal muscle. The injured group sections did not consistently show these characteristics; many fibers in these sections exhibited a rounded contour, variable stain intensities, and greater interfiber distances. A substantially increased amount of connective tissue was also observed on the injured group sections. Conclusion: This experimental model found a morphological change in muscle distant from the site of thermal injury covering 45% of the body surface. Key words: Morphology. Muscle Fibers, Skeletal. Connective Tissue. Burns. Rats. RESUMO Objetivo:A lesão térmica conduz o organismo a processos catabólicos a fim de reparar a área lesada. O propósito do presente estudo foi avaliar os efeitos da lesão térmica por escaldadura na morfologia das fibras musculares de um músculo distante da lesão. Métodos: Foram utilizados 30 ratos Wistar, divididos em: Grupo submetido à lesão térmica por escaldadura (S) e Grupo Controle (C). A escaldadura foi provocada em 45% da superfície corporal dos animais e padronizada pelo peso corpóreo. A eutanásia ocorreu nos períodos pós-lesão de quatro, sete e 14 dias. Retirou-se a parte média dos músculos gastrocnêmio medial os quais foram submetidos à técnica histológica de Hematoxilina-Eosina e Picrosírius. Resultados: O aspecto poligonal das fibras musculares, com núcleos periféricos, bem como a distribuição eqüidistante das mesmas, característico das descrições da musculatura normal, verificado nos animais do grupo C não foi uma constante nas fibras do músculo dos animais do grupo S. Nestes, muitas fibras exibiram contorno arredondado, diferentes intensidades de marcação bem como maior distanciamento entre as mesmas. Observou-se ainda aumento substancial da quantidade de tecido conjuntivo no grupo S. Conclusão: Houve alteração da morfologia do músculo distante da lesão como resposta à lesão térmica de 45% em modelo experimental. Descritores: Morfologia. Fibras Musculares Esqueléticas. Tecido Conjuntivo. Queimaduras. Ratos.

An optimized animal model for partial and total skin thickness burns studies

“…Different burn models have been presented. Methods for producing experimental burns included boiling water 6 , heated brass bar 7 , heated (130°C) aluminum plate 8 , a constant-temperature hot plate (170ªC) placed over stainless steel rods 9 and scalding over 45% of the body surface 10 . In the present study, skin burns were inflicted by transference of energy (heat) using direct conduction (Copper/skin) utilizing different increasing temperatures (100°C, 150°C and 200°C).…”

Relation between microcurrent therapy and satellite cells in the regeneration of induced skeletal muscle injury in rat

“…In accordance,some authors stated that thermal injury of gastrocnemius muscle of rat revealed greater interfiber distances and substantially increased amount of connective tissue [1]. In accordance,some authors stated that thermal injury of gastrocnemius muscle of rat revealed greater interfiber distances and substantially increased amount of connective tissue [1].…”

“…Severe injuries to the skeletal muscle result in muscle weakness, which delays recovery, exposes patients to neuromuscular complications that increase hospital stay, and increase the probability of mortality [1]. In muscular dystrophy, an imbalance between muscle damage and muscle repair through stem cell-mediated regeneration is thought to contribute to progressive decline in muscle function [2].…”

Effect of low-intensity therapeutic ultrasound on wound healing in rats subjected to third-degree burns

“…Burns are generally caused by flammable substances and overheated liquids 2 . Depending on the severity of the injury, epidermal necrosis can occur, which affects the dermis and the underlying tissues, and can lead to systemic changes that compromise other organs and tissues that are remote from the burnt area 3 . In addition, hypovolemic shock and infectious or inflammatory diseases can occur, which are among the most challenging situations that patients with burns and their care teams have to confront.…”