Long-term voluntary wheel running effects on markers of long interspersed nuclear element-1 in skeletal muscle, liver, and brain tissue of female rats

• Published in: American Journal of Physiology: Cell Physiology 2022-09, Vol.323 (3), p.C907-C919
• Main Authors: Osburn, Shelby C., Mesquita, Paulo H. C., Neal, Frances K., Rumbley, Melissa N., Holmes, Matthew T., Ruple, Bradley A., Mobley, Christopher B., Brown, Michael D., McCullough, Danielle J., Kavazis, Andreas N., Roberts, Michael D.
• Format: Article
• Language: English
• ISSN: 0363-6143; 1522-1563
• DOI: 10.1152/ajpcell.00234.2022

We sought to determine the effects of long-term voluntary wheel running on markers of long interspersed nuclear element-1 (L1) in skeletal muscle, liver, and the hippocampus of female rats. In addition, markers of the cGAS-STING DNA-sensing pathway that results in inflammation were interrogated. Female Lewis rats ( n = 34) were separated into one of three groups including a 6-mo-old group to serve as a young comparator group (CTL, n = 10), a group that had access to a running wheel for voluntary wheel running (EX, n = 12), and an age-matched group that did not (SED, n = 12). Both SED and EX groups were carried out from 6 mo to 15 mo of age. There were no significant differences in L1 mRNA expression for any of the tissues between groups. Methylation of the L1 promoter in the soleus and hippocampus was significantly higher in SED and EX than in CTL group ( P < 0.05). ORF1p expression was higher in older SED and EX rats than in CTL rats for every tissue ( P < 0.05). There were no differences between groups for L1 mRNA or cGAS-STING pathway markers. Our results suggest there is an increased ORF1 protein expression across tissues with aging that is not mitigated by voluntary wheel running. In addition, although previous data imply that L1 methylation changes may play a role in acute exercise for L1 RNA expression, this does not seem to occur during extended periods of voluntary wheel running.