Mice overexpressing PGC-1α in skeletal muscles are most likely to exhibit what change relative to wild-type mice?

• A. Increased body weight
• B. Higher body temperature
• C. Lower body weight
• D. Reduced muscle strength

Answer: (C)

Mice overexpressing PGC-1α in skeletal muscles are likely to exhibit lower body weight relative to wild-type mice due to the role of PGC-1α in regulating energy metabolism. PGC-1α is a transcriptional coactivator that promotes mitochondrial biogenesis and enhances oxidative metabolism in skeletal muscle. This increased mitochondrial content and metabolism leads to greater energy expenditure. Consequently, these mice may utilize energy more efficiently and burn more calories than their wild-type counterparts.

Additionally, PGC-1α is known to induce the expression of genes involved in the transition from glycolytic to oxidative muscle fibers, which further supports enhanced endurance and metabolic activity. This metabolic shift can contribute to a leaner body composition, as fatty acids are utilized more effectively for energy production rather than stored as fat.

This change is in contrast to the other options, which either suggest an increase in body weight or other physiological responses that do not align with the known effects of PGC-1α overexpression in skeletal muscle. Thus, the overexpression of PGC-1α leads to a net decrease in body weight through enhanced metabolic activity and energy expenditure.