Skeletal muscle wasting after burn is regulated by a decrease in anabolic signaling in the early flow phase.

Area of Science:

• Biomedical Sciences
• Physiology
• Muscle Biology

Background:

• Burns induce a catabolic stress response, leading to skeletal muscle wasting.
• Understanding post-burn muscle wasting mechanisms is crucial for developing interventions.

Purpose of the Study:

• To investigate the effects of severe scald burns on skeletal muscle anthropomorphology and key protein expression in rats.
• To identify molecular mechanisms underlying post-burn muscle wasting.

Main Methods:

• Female rats underwent sham, 10%, or 40% total body surface area scald burns.
• Muscle weight, fiber type composition, and protein expression (eEF2, pAKT, MURF1, Atrogin-1, FOXO3A) were analyzed 10 days post-injury.
• Mitochondrial function (COX/SDH) and apoptosis (caspase-3) were assessed.

Main Results:

• Severely burned rats showed reduced weight gain and lower muscle-to-body weight ratios in Soleus (SOL) and Extensor Digitorum Longus (EDL) muscles.
• EDL muscle had fewer total fibers, while SOL showed increased type 1 and decreased type 2 fibers post-burn.
• Severe burns decreased eEF2 and pAKT expression, increased MURF1/Atrogin-1 in SOL (but decreased MURF1 in EDL), and lowered FOXO3A in both muscles, without affecting mitochondrial function or apoptosis.

Conclusions:

• Scald burns induce significant changes in muscle anthropomorphology and protein regulation, impacting both protein synthesis and breakdown pathways.
• The Soleus muscle exhibits more pronounced catabolic changes compared to the Extensor Digitorum Longus following severe burns.
• These findings provide insights into the molecular basis of post-burn muscle wasting and potential therapeutic targets.