How fruit flies help researchers understand insulin resistance and diabetes
Fruit flies help researchers understand human diseases like Alzheimer’s disease and cancer. Now scientists have developed an insulin resistant fruit fly to help them understand the metabolic underpinnings that are hallmarks of type 2 diabetes. The goal is developing new treatment options for the disease that is linked to obesity and poor diet.
Experiments show how different diets could lead to type 2 diabetes
For their experiments the researchers fed the fruit flies a high nutrient diet to mimic what happens when humans become obese and insulin resistant.
Johannes H. Bauer, principal investigator for the study at Southern Methodist University, Dallas explained in a media release that the new model poses ‘endless possibilities’ for learning how to treat obesity and insulin resistance “…as well as drug treatments for the condition, as well as how to treat obesity, how to block insulin resistance and how metabolic changes from a specific diet develop.”
The researchers wanted to see if different diets led to diabetes. They fed one group a high-carbohydrate diet and the other a diet over-loaded with protein.
In each instance the fruit flies developed insulin resistance, which was a surprise. The scientists expected a high carbohydrate diet to lead to obesity. What they didn’t anticipate was how quickly a high protein diet also led to insulin resistance even though they lost weight with higher levels of dietary protein.
The carbohydrate diet mimicked the effect in humans from eating too many sweets, french fries, pasta and ice cream. The over-loaded protein diet would be similar to the popular Atkins diet.
Carb-loaded flies gain weight. Protein-loaded flies gain and then lose weight. So the two diets have exactly opposite effects on metabolism,” Bauer said. “But too much of either one of them causes insulin resistance. That surprised us.”
Fruit flies given a high carbohydrate diet became less fertile and laid fewer eggs. The high protein diet flies laid more eggs initially, but too much protein had the opposite effect. Both diets shortened lifespan. Both diets induced insulin resistance.
“The carb data imply a linear relationship between carb levels and health. The more carbs, the more weight, the more sugar storage and fat, the more insulin resistance and the less fertility,” Bauer said.
“But with protein, this relationship becomes parabolic, meaning all readouts go up, then come down again. The decreased storage we liken to a catabolic state that is primarily destructive for the body’s optimum metabolic functioning, such as the ketosis typically seen in people eating Atkins-type diets.”
Until now researchers used mice and rats to study diabetes. The fruit fly has a short lifespan which will allow researchers to quickly learn more about metabolic changes that happen with type 2 diabetes. The hope is that the new model will lead to new treatments, given the alarming increase in diabetes rates in the United States.
Biochimica et Biophysica Acta – Molecular Basis of Disease
“Development of diet-induced insulin resistance in adult Drosophila melanogaster”
Siti Nur Sarah Morris et al
Image credit: Wikimedia commons