Systemic low-grade inflammation does not decrease skeletal muscle mass and protein synthesis in old rats

Area of Science:

• Gerontology
• Physiology
• Immunology

Background:

• Age-associated low-grade systemic inflammation is a potential contributor to sarcopenia.
• Sarcopenia, the loss of skeletal muscle mass and function, is a common aging-related condition.

Purpose of the Study:

• To investigate the relationship between persistent low-grade inflammation and skeletal muscle mass and protein synthesis in aged rats.
• To determine if age-associated inflammation directly impacts muscle health.

Main Methods:

• Comparison of male 24-month-old Wistar rats with (LGI group) and without (C group) persistent low-grade inflammation.
• Quantification of tissue protein synthesis rates using the L-[1-(13)C]-valine flooding dose method.
• Measurement of body weight, gastrocnemius muscle, spleen, liver, and small intestine weights.

Main Results:

• No significant differences in body weight, gastrocnemius muscle, or spleen weights between LGI and C groups.
• Increased liver and small intestine weights in the LGI group compared to the C group.
• Skeletal muscle protein synthesis rates were not significantly different, but liver protein synthesis was higher in the LGI group.

Conclusions:

• Persistent low-grade inflammation in aged rats does not lead to sarcopenia.
• Age-associated low-grade systemic inflammation appears to occur independently of sarcopenia.
• The findings suggest distinct pathways for inflammation and muscle aging.