In a recent study published in the journal Development, Dutra Nunes and Drummond-Barbosa’s research uniquely analyzes the effects of a high sugar diet, obesity and water intake on metabolism, oogenesis and fertility in Drosophila melanogaster, otherwise known as the common fruit fly.
“One of the novelties of this paper is that we didn’t only show that a high-sugar diet reduces the fertility of flies, but we also showed which steps of oogenesis are affected, and which process in each step is being affected,” says Dutra Nunes.
Existing studies do not distinguish between the effects of a high-sugar diet and obesity, which makes it difficult to investigate the underlying cause behind decreased fertility.
“We were able to dissociate the effects of obesity and high sugar and show that obesity is not what causes the reduction in fertility,” adds Drummond-Barbosa. “This highlights the importance of carefully separating the contributions of diet versus obesity in future studies not only in fruit flies but also in mammals.”
Drosophila are commonly used in biomedical research, and are the main tool for fertility research by Dutra Nunes in the Drummond-Barbosa Lab.
Dutra Nunes notes that there is a high degree of similarity between the genes in flies and in humans, so Drosophila can provide an excellent model for experiments that are challenging or not feasible to conduct on humans, such as genetic manipulation or diet alteration.
“Fruit flies offer major advantages as we progress towards identifying the cellular and molecular mechanisms underlying the effects of a high sugar diet,” adds Drummond-Barbosa. “The powerful genetic tools available, fast generation time, and large sample sizes make it possible to combine cutting edge research with high scientific rigor.”
Dutra Nunes and Drummond-Barbosa compared reproductive changes in Drosophila on a high-sucrose diet to that of a control group without manipulation of the diet. In the experimental flies, fat storage quickly increased in one week, reaching much higher levels than in the control group.
An additional group of Drosophila were genetically altered to increase fat accumulation and model obesity on a normal diet. Fertility remained unchanged in these manipulated flies.
A resulting loss in egg production and hatching rates of female flies maintained on a high-sugar diet led Dutra Nunes and Drummond-Barbosa to conclude that a high-sugar diet, and not obesity, is the primary cause of female infertility.
They also observed an increase in death of developing germ cells at two distinct stages of oogenesis in the flies fed a high sugar diet.
“If you have some of the steps of oogenesis surviving less, that means you’ll have fewer eggs generated,” says Dutra Nunes. “That is what’s causing a decrease in fertility in flies.”
Apart from diet, Dutra Nunes also found that elevated water intake had a powerful metabolic effect counteracting high sugar consumption.
“The dietary supplementation of water to obese flies on a high-sugar diet was able to reverse the negative effects on fertility without changing the level of obesity,” he says. The water supplementation also reversed the high glucose levels present in the bodies of flies on a high-sugar diet.
Hydration’s healing reversal of reduced egg production provide a foundation for future studies to explore the relationship between water consumption, high glucose levels and fertility.
Dutra Nunes intends to explore under-researched elements and their roles in reproductive processes.
“We are now taking unbiased approaches such as proteomics and metabolomics to discover new points of connection between high glucose, water and other effectors of a high-sugar diet and test their effects on fertility,” he says.
He hopes that his research with Drummond-Barbosa might inspire further research into possible therapeutic interventions in humans to reverse some of the effects of the Western diet that are causing decreased fertility and other diseases.