There's plenty of evidence that when possible, it's more healthy for people to stay physically active than it is for them to have a sedentary lifestyle, especially as people age. Physical inactivity is a leading contributor to mortality; Heart disease is the world's leading cause of death, and inactivity can increase the risk of cardiovascular problems. A sedentary lifestyle also increases the likelihood that a person will develop insulin resistance. Insulin regulates the level of sugar in the blood, and when the body stops releasing or stops responding to insulin, diabetes occurs. Scientists have now identified showed an enzyme called NOX4 links physical inactivity and insulin resistance.
This research indicated that during aging, the levels of reactive oxygen species (ROS) in skeletal muscle drops, and this process is involved in insulin resistance. NOX4 is crucial for the beneficial increase in ROS production during exercise and the subsequent changes that happen, which are relevant to metabolic health. The study, which has been reported in Science Advances, could help scientists create drugs that promote the NOX4 enzyme's activity to maintain metabolic health or protect against muscle wasting.
Skeletal muscle produces ROS all the time, and when we exercise, it generates even more, said study leader Professor Tony Tiganis of the Monash University Biomedicine Discovery Institute (BDI). “Exercise-induced ROS drives adaptive responses that are integral to the health-promoting effects of exercise,” he said.
Using a mouse model, the researchers determined that NOX4 levels went up in skeletal muscle after exercise, which caused an increase in ROS. There are changes in response to that ROS increase, and those can prevent insulin resistance in mice, which happens during aging or obesity. The levels of NOX4 are linked directly to insulin sensitivity, said the researchers.
Animal studies suggested that the amount of NOX4 in skeletal muscle decreases as animals age, and that causes a reduction in insulin sensitivity, said Tiganis.
“Triggering the activation of the adaptive mechanisms orchestrated by NOX4 with drugs, might ameliorate key aspects of aging, including the development of insulin resistance and type 2 diabetes,” Tiganis added.
“One of these compounds is found naturally, for instance, in cruciferous vegetables, such as broccoli or cauliflower, though the amount needed for anti-aging effects might be more than many would be willing to consume.”