Depleting microbiome with antibiotics can affect glucose metabolism

A new study has found that mice that have their microbiomes depleted with antibiotics have decreased levels of glucose in their blood and better insulin sensitivity. The research has implications for understanding the role of the microbiome in diabetes. It also could lead to better insight into the side effects seen in people who are being treated with high levels of antibiotics.

The microbiome is the collection of microorganisms that live in an animal's body, many of which are essential for health. Previous studies have shown that mice whose microbiomes are deficient in certain types of bacteria are more likely to develop diabetes. There is also some evidence that certain microbes may be protective against diabetes.

The researchers didn't set out to look specifically at how antibiotic-induced depletion influences glucose levels. They wanted to look at the circadian (24 hour) rhythms of mouse metabolism when the microbiome is depleted. This type of research is often done with mice raised in germ-free environments.

After treating the mice, the investigators observed that there was a large decrease in the diversity of microorganisms present in their guts, as expected. When they looked at the metabolisms of the mice, they found that they were able to clear glucose from their blood much faster than expected.

Further studies showed that the colon tissue in the mice was acting as a kind of sink for the glucose -- absorbing the extra sugar and thereby reducing its levels in the blood. This behavior fit the observation that the mice had colons that were greatly increased in size.

The researchers then discovered that these metabolic changes were actually related to changes in liver function and to the bile acids that were being released by the liver. The mice did not have changes in body fat composition or in what they ate -- the two things that normally influence glucose metabolism and are known to play a role in type 2 diabetes in humans.

See:

Amir Zarrinpar, Amandine Chaix, Zhenjiang Z. Xu, Max W. Chang, Clarisse A. Marotz, Alan Saghatelian, Rob Knight, Satchidananda Panda. Antibiotic-induced microbiome depletion alters metabolic homeostasis by affecting gut signaling and colonic metabolism. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-018-05336-9

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology