Atmospherically relevant PM_2.5 promotes age-related muscle atrophy in an age-dependent manner

Area of Science:

• Aging and environmental health
• Skeletal muscle physiology
• Toxicology

Background:

• Skeletal muscle quality is crucial for healthy aging.
• Environmental factors influencing muscle aging are understudied.
• Particulate matter 2.5 (PM2.5) is a prevalent environmental pollutant.

Purpose of the Study:

• To investigate the age-specific effects of PM2.5 exposure on skeletal muscle.
• To determine the impact of PM2.5 on muscle atrophy, oxidative stress, and mitochondrial function across different age groups.
• To identify potential resistance to PM2.5-induced damage in middle-aged individuals.

Main Methods:

• Male mice (1, 6, and 15 months old) were exposed to PM2.5 (50 μg/m³, 2 h/day) for 5 days.
• Skeletal muscles were analyzed one month post-exposure.
• Measurements included body weight, lean body weight, fat levels, oxidative stress markers, Myostatin expression, and mitochondrial morphology (fission, mitophagy).

Main Results:

• PM2.5 exposure significantly affected total body weight and lean body weight in an age-dependent manner.
• PM2.5 exposure induced age-related muscle atrophy, increased oxidative stress, and elevated Myostatin expression in older mice.
• Mitochondrial damage, including increased fission and mitophagy, was observed in young and older mice, with more pronounced effects in older adults.

Conclusions:

• PM2.5 exposure exerts age-specific detrimental effects on skeletal muscle.
• Young and aging mice exhibit distinct skeletal muscle responses to PM2.5.
• Middle-aged mice demonstrated resistance to PM2.5-induced skeletal muscle damage.