Clock Gene Expression Modulation by Low- and High-Intensity Exercise Regimens in Aging Mice

Area of Science:

• Chronobiology and Exercise Physiology
• Molecular Biology and Aging Research

Background:

• The circadian rhythm, regulated by clock genes, influences sleep, metabolism, and physiological functions.
• Aging can disrupt circadian rhythms, increasing health risks, and while exercise benefits circadian synchronization, the impact of exercise intensity on clock gene expression during aging is understudied.

Purpose of the Study:

• To investigate the differential expression of key clock genes (Clock, Arntl, Per1, Per2, Cry1, Cry2, Nr1d1) in response to variable-intensity aerobic swimming training in aging mice.
• To determine if different exercise intensities interfere with the genomic regulation of the circadian rhythm in aging mice.

Main Methods:

• Aging mice were subjected to low- and high-intensity aerobic swimming exercise.
• Heart and gastrocnemius muscle tissues were analyzed using cDNA synthesis and quantitative Polymerase Chain Reaction (qPCR).
• Expression levels of seven core clock genes were quantified.

Main Results:

• Low-intensity exercise significantly altered clock gene expression in the gastrocnemius muscle (p < 0.05).
• High-intensity exercise showed no statistically significant effects on clock gene expression (p > 0.05).
• Low-intensity exercise increased Per1 gene expression in the heart (p = 0.031), while other heart tissues were unaffected; exercise did not alter body weight or lactate thresholds, but low-intensity exercise improved exercise capacity.

Conclusions:

• Chronic low-intensity exercise modulates clock gene expression in aging mice, particularly in skeletal muscle.
• Exercise intensity plays a critical role in the genomic regulation of the circadian rhythm during aging.
• Findings suggest potential benefits for circadian medicine, including improved exercise capacity and cardiac function through low-intensity exercise regimens.