Protein Expression in the Gastrocnemius Muscle of a Rodent Shrapnel-Injury Model

Area of Science:

• Biomedical Engineering
• Toxicology
• Muscle Physiology

Background:

• Shrapnel injuries often result in retained metal fragments, posing unknown long-term health risks.
• The effects of embedded metals on protein damage and muscle repair pathways are not well understood.

Purpose of the Study:

• To investigate the long-term effects of military-relevant embedded metals on rat gastrocnemius muscle.
• To assess metal-induced oxidative damage and alterations in muscle repair pathways.

Main Methods:

• Implantation of metal pellets (iron, copper, lead, cobalt, depleted uranium) into rat gastrocnemius muscle for up to 12 months.
• Analysis of inducible nitric oxide synthase (iNOS), endothelial nitric oxide synthase (eNOS), matrix metalloproteinases (MMP-2, MMP-9), and hydroxynonenal-modified proteins.
• Quantification of metal levels in muscle tissue.

Main Results:

• No significant differences in metal levels were observed, except for iron and cobalt at 1 month.
• Significant decreases in iNOS and eNOS expression were found in lead and depleted uranium groups at 6 and 12 months.
• Increased levels of hydroxynonenal-modified proteins were observed in iron, copper, lead, and depleted uranium groups.

Conclusions:

• Embedded metals can induce long-term oxidative damage in muscle tissue.
• Specific metals, like lead and depleted uranium, negatively impact nitric oxide production pathways.
• These findings highlight potential risks associated with retained metal fragments from injuries.