Sudden decrease in physical activity evokes adipocyte hyperplasia in 70- to 77-day-old rats but not 49- to 56-day-old...

Area of Science:

• Physiology
• Obesity Research
• Adipose Tissue Biology

Background:

• Physical inactivity is a known trigger for obesity development in both humans and rodents.
• Understanding how reduced physical activity impacts adipose tissue is crucial for metabolic health research.

Purpose of the Study:

• To investigate the effects of abruptly ceasing physical activity on adipose tissue characteristics in rats of different ages.
• To determine age-dependent differences in the response of adipose tissue to wheel lock (WL).

Main Methods:

• Male Wistar rats were divided into sedentary (SED), running (RUN), and wheel lock (7d-WL) groups.
• Wheel access was restricted for the final 7 days in the 7d-WL group.
• Adipose tissue characteristics, including fat mass, adipocyte size and number, and gene expression, were analyzed at 49-56 and 70-77 days of age.

Main Results:

• Wheel lock (WL) induced more significant changes in older rats (70-77 days) compared to younger rats (49-56 days).
• In older rats, 7d-WL led to increased fat mass, adipocyte number (hyperplasia), and cyclin A1 mRNA in adipose tissue.
• Younger rats showed minimal changes in adipose tissue characteristics following WL, indicating a protective effect.

Conclusions:

• Adipose tissue in older rats is more susceptible to the obesogenic effects of physical activity cessation.
• The primary adaptive mechanism in older rats appears to be adipose tissue expansion through hyperplasia.
• Younger rats exhibit resilience to the negative impacts of reduced physical activity on adipose tissue parameters.