Decoding the decline: unveiling drivers of sarcopenia.

Area of Science:

• Gerontology
• Muscle Biology
• Molecular Biology

Background:

• Sarcopenia, age-related muscle loss, requires molecular targets for therapy.
• Preclinical rodent models are crucial for aging and sarcopenia research.
• A standardized classification system for sarcopenia in rodent models is needed.

Purpose of the Study:

• To implement a clinically-relevant sarcopenia classification system in aged mice.
• To investigate physiological, molecular, and energetic changes associated with sarcopenia.
• To identify sex-dependent differences in sarcopenia progression.

Main Methods:

• Utilized a sarcopenia classification system in aged C57BL/6J mice.
• Conducted detailed physiological, molecular, and energetic analyses.
• Examined sarcopenia prevalence and alterations across both sexes.

Main Results:

• Sarcopenia prevalence varied between sexes in aged mice.
• Male mice exhibited decreased mitochondrial biogenesis, oxidative capacity, and AMPK-autophagy signaling.
• Female mice showed fewer molecular alterations compared to males.

Conclusions:

• Factors beyond chronological age are critical for defining the sarcopenic phenotype in rodent models.
• Significant sexual dimorphism exists in age-related muscle decline and molecular alterations.
• Findings provide insights into sex-dependent mechanisms of sarcopenia progression.