A team from the Biocentre of the Julius-Maximilians-Universität of Würzburg, in Bavaria (Germany) has shown that physical exercise can slow down the production of insulin.
Insulin is an essential hormone for humans and many other living beings. Its best known function is to regulate sugar metabolism. It is well known how he does it. Much less is known regarding how the activity of insulin-producing cells and consequently its secretion is controlled.
In their work, published in the scientific journal ‘Current Biology’, the researchers used the fruit fly ‘Drosophila melanogaster’ as the object of study. Interestingly, this fly also secretes insulin following eating. However, in the fly, the hormone does not come from the pancreas as in humans, but is released by nerve cells in the brain.
The research group has shown that the fly’s physical activity has a strong effect on its insulin-producing cells. For the first time, the researchers electrophysiologically measured the activity of these cells in walking and flying Drosophila.
The result: when the ‘Drosophila’ begins to walk or fly, its insulin-producing cells are immediately inhibited and. When the fly stops moving, the activity of the cells rapidly increases once more, shooting up above normal levels.
“Our hypothesis is that the low activity of insulin-producing cells during walking and flight contributes to the supply of sugars to meet the increased energy demand. We suspect that the increased activity following exercise helps replenish the fly’s energy reserves. , for example in the muscles”, commented Dr. Sander Liessem, first author of the publication.
Blood sugar is not involved in regulation
The team was also able to show that rapid, behavior-dependent inhibition of insulin-producing cells is actively controlled by neural pathways. “It is largely independent of changes in the blood sugar concentration of the fly. It makes perfect sense that the body would anticipate a higher energy demand in this way to avoid extreme fluctuations in blood sugar levels,” he said. explained Dr. Martina Held, co-author of the study.
Do the results allow us to draw conclusions regarding humans? Probably, according to the authors. “Although the release of insulin in fruit flies is mediated by different cells than in humans, the insulin molecule and its function have hardly changed over the course of evolution,” says Jan Ache.
In the last 20 years, using ‘Drosophila’ as a model organism, many fundamental questions have already been answered that might also contribute to a better understanding of metabolic defects in humans and associated diseases, such as diabetes or obesity.
“An exciting point is that lower insulin activity contributes to healthy aging and longevity,” Sander Liessem stressed. This has already been shown in flies, mice, humans, and other species. The same goes for an active lifestyle. “Our work shows a possible link that explains how physical activity might positively affect insulin regulation through neural signaling pathways,” he added.
Next, Jan Ache’s team plans to investigate which neurotransmitters and neural circuits are responsible for the changes in activity observed in the fly’s insulin-producing cells.
This is likely to present a challenge: a plethora of messenger substances and hormones are involved in neuromodulatory processes, and individual substances can have opposite or complementary effects in combination.
The group is analyzing the multiple ways in which insulin-producing cells process information from outside. They are also investigating other factors that might influence the activity of these cells, for example the age of the fly or its nutritional status.
