JMU Scientists Discover How Fruit Flies Regulate Insulin with Age, Offering Insights into Human Metabolism

Fruit Flies Shed Light on Human Insulin Regulation

Insulin is critical in regulating metabolism across many species, including humans. Scientists at Julius-Maximilians-Universität Würzburg in Germany have made groundbreaking discoveries about insulin production in fruit flies, providing insights that could be relevant to human metabolic health.

Understanding Insulin in Drosophila

While humans produce insulin in the pancreas, fruit flies, belonging to the species Drosophila, generate insulin in specialized brain cells. These cells secrete insulin directly into hemolymph, the insect’s circulatory fluid. This system mirrors human insulin regulation, offering a valuable model for study.

Insulin facilitates energy storage and absorption when food is plentiful. During famines, insulin production decreases, prompting the body to conserving energy or seeking alternative sources. This balanced system is crucial for survival, and its disruption can lead to diabetes and metabolic disorders.

Insulin Secretion in Fruit Flies

Published in the scientific journal eLife, the study focused on how insulin-producing cells (IPCs) in fruit flies respond to changes in energy balance. Dr. Jan Ache and his team tracked the activity of individual IPCs in living fruit flies under varying conditions.

The researchers discovered that IPCs release insulin only when the flies consume sugar, not when it is directly injected into the hemolymph. This behavior closely resembles the incretin effect observed in humans, suggesting a more complex mechanism involving gut hormones governs insulin secretion.

The Role of Aging in Insulin Production

The study also revealed that IPC activity decreases with age, similar to human insulin production. This decline may indicate changes in how organisms process sugar as they grow older.

Impact on Foraging Behavior

The relationship between insulin secretion and foraging behavior in fruit flies was another focus of the study. Scientists used optogenetics to simulate the insulin response after a meal, observing that IPCs play a minor role compared to other nerve cells in regulating foraging behavior.

Implications for Human Health

Although humans and fruit flies are vastly different, they share similarities in genetics and metabolism. These findings could help researchers gain a deeper understanding of metabolic regulation and its role in human health, particularly in the context of diseases like diabetes.

“With our experiments, we have refined our knowledge of the circuits that control insulin secretion in fruit flies,” said Jan Ache. “This now enables further investigations, which could ultimately lead to findings that are relevant to human health and diseases such as diabetes.”

The study’s unique insights could pave the way for new treatments by elucidating the mechanisms that control insulin production and secretion. By understanding these processes in fruit flies, researchers may uncover novel approaches to addressing metabolic disorders in humans.

Reference: “Nutritional state-dependent modulation of insulin-producing cells in Drosophila” by Rituja S Bisen, Fathima Mukthar Iqbal, Federico Cascino-Milani, Till Bockemühl and Jan M Ache, 29 January 2025, eLife.
DOI: 10.7554/eLife.98514