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:
Posted by Dr. Tim Sandle,
Pharmaceutical Microbiology