Effects of short-term physical training on the interleukin-15 signalling pathway and glucose tolerance in aged rats
Luciele Guerra Minuzzi1, Luciana Renata da Conceição2, Vitor Rosetto Muñoz2
1Laboratory of Molecular Biology of Exercise (LaBMEx), University of Campinas (UNICAMP), Limeira, São Paulo, Brazil; University of Coimbra Research, Center for Sport and Physical Activity, Faculty of Sport Sciences and Physical Education, Coimbra, Portugal; Exercise and Immunometabolism Research Group, Post-Graduation Program in Movement Sciences, Department of Physical Education, São Paulo State University (UNESP), Presidente Prudente, SP, Brazil.
Purpose:
Interleukin-15 (IL-15) is a myokine that has been proposed to modulate skeletal muscle and adipose tissue mass, as well as insulin sensitivity. However, the evidence suggesting a role for IL-15 in improving whole-body insulin sensitivity and decreasing adiposity comes mainly from studies using supraphysiological levels of this cytokine. This study examined the effect of a short-term exercise training protocol on the protein content of IL-15, it's signaling pathway, and glucose tolerance in aged rats.
Methods:
Fourteen Wistar rats were divided into Young Sedentary (Young, n = 4); Old Sedentary (Old, n = 5); Old Exercise (Old.Exe, n = 5) groups. The animals from the exercised group were submitted to a short-term physical exercise protocol for five days. At the end of physical training and after 16 h of the last exercise session, the animals were euthanized, and tissue collection was done.
Results:
Physical exercise decreased epididymal and mesenteric fat mass and promoted positive effects on glucose tolerance and insulin sensitivity. Muscle IL-15 protein levels were not changed following the short-term physical exercise training with no alterations in the post-exercise IL-15-JAK/STAT signaling pathway. We found a tendency to increased HIF1α and a significant increase in its regulator, PHD2, in the skeletal muscle after exercise.
Conclusion:
The elderly rats submitted to short-term aerobic physical training did not present skeletal muscle alteration in the protein content of the IL-15 and IL-15-JAK/STAT signaling pathway. However, short-term aerobic physical training was able to modulate the expression of HIF1α and its regulator PHD2, suggesting an essential role of these proteins in improving post-exercise glucose tolerance and insulin sensitivity in elderly rats.
