Adipose tissue is a layer of tissue present beneath the skin of humans. This tissue is a simple reservoir of energy during the need and contributes significantly to the regulation of metabolism.
The adipose tissue is involved in releasing various molecules into the bloodstream, including microRNAs that modulate the expression of key genes in different parts of the organism, including the liver, pancreas, and muscles.
The regulation of the microRNAs by adipose tissue is affected by aging and obesity. The impaired production of these microRNAs hence favors the development of diseases such as diabetes and dyslipidemia (abnormal amount of lipids).
‘Aerobic exercise reverses the degenerative process by increasing the expression of an enzyme in the adipose tissue responsible for an organism's metabolic health. This sheds light on the strategies for combating the harmful effects of aging and obesity.’
However, regular aerobic exercise can reverse this degenerative process, as per a study published in the journal "Proceedings of the National Academy of Sciences (PNAS)".
Metabolic regulation in adipose tissue:
"Experiments with mice and humans have shown that aerobic exercise stimulates the expression of an enzyme called DICER, which is essential to the processing of these microRNAs. We, therefore, observed an increase in production of these regulatory molecules by adipose cells, with several benefits for the metabolism," said Marcelo Mori, a professor at the University of Campinas's Institute of Biology (IB-UNICAMP) in the state of São Paulo, Brazil, and one of the principal investigators for the project.
The mice were subjected to a 60-minute treadmill running protocol for eight weeks, whereas humans were subjected to six weeks of high-intensity interval training (HIIT). The varied effect was observed in both younger volunteers, aged about 36, and older subjects, aged about 63.
The experiment in genetically modified mice that do not express DICER in adipose cellsshowed that the beneficial effects of aerobic exercise were far smaller.
"In this latest study we found that aerobic exercise, like caloric restriction, can reverse the drop in DICER expression and microRNA production thanks to the activation of a very important metabolic sensor, the enzyme AMPK [adenosine monophosphate-activated protein kinase]," Mori said.
It was observed that aerobic exercise activated AMPK in muscle cells and this induced DICER expression in adipose cells. The result was verified when scientists injected blood serum from a trained animal into a sedentary animal. It was observed the DICER levels increased in the adipose tissue. The same was seen in incubated cultured adipocytes with serum from trained mice.
The team identified increased expression of a molecule called miR-203-3p, on training and caloric restriction. The microRNA is also responsible for promoting metabolic adjustment in adipocytes.
"This finding suggests trained individuals have one or more molecules in their bloodstream that directly induce a metabolic improvement in adipose tissue. If we can identify these molecules, we can investigate whether they also induce other benefits of aerobic exercise, such as cardioprotection. Moreover, we may think about converting this knowledge into a drug at some stage", Mori said.
Therefore, the study also highlighted the role of enzyme DICER on metabolic health and its contribution to degenerative processes.