Uncovering the Microbiome-Obesity Link

Despite numerous studies linking gut microbiome changes and dysbiosis to obesity and metabolic syndromes, the specifics of these correlations are still unclear and require more research. However, Yale University researchers recently observed a microbiome-obesity link, which showed increased appetite as well as increased secretion of insulin in murine models, potentially uncovering therapeutic treatments for obesity.

Scientists have already recognized that shifts in the human gut microbiome can be linked to both obesity and metabolic disorders in humans and rodents. In this particular study, researchers provided a newly discovered trigger that explains the link in rodents, but scientists are unsure if it translates to humans.

Inspiration for this study stemmed from researchers observing high-fat diets and higher acetate levels, which has been shown to affect appetite, in rodents’ blood streams. This increase produced insulin secretion; however, scientists could not explain the acetate origin.

Researchers observed that the levels of acetate in germ-free mice and those treated with antibiotics were relatively low; however, restoring the gut microbiota caused higher acetate production. In addition, high-fat diets increased acetate levels even further. In combination, these two studies reveal a correlation between changes in the gut microbiome in response to diet modifications and increasing acetate production.

Insulin secretion is not directly stimulated through acetate and pancreatic cells. Instead, acetate activates the brain to send a signal through the vagus nerve, which controls the heart, lungs, and digestive system, to the pancreas. This signal is key to identifying a potential therapy marker. A centrally mediated mechanism causes acetate to trigger additional insulin secretion from specific cells in response to glucose. It also encourages hormone secretions that results in increased appetite and food intake.

This research builds on previous studies that found a microbiome-obesity link. Future research hopes to find the factor that influences metabolism, which is extremely important for further research to link the microbiome and obesity.

References

Perry, R.J., Peng, L., Barry, N.A., et al. Acetate mediates a microbiome–brain–β-cell axis to promote metabolic syndrome. Nature. 2016. 534;213-17. doi:10.1038/nature18309

Frost et al., “The short-chain fatty acid acetate reduces appetite via a central homeostatic mechanism,”Nature Communications. 2014. doi:10.1038/ncomms4611.

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