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Healthcare Journal of new orleans
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NOV / DEC 2014
53
on motor activity, anxiety, depression and
exploratory behavior, Bruce-Keller noticed
striking differences between the two groups
of mice.While none of themice became obese,
themice who received a gut microbiome from
the HFD mice showed consistent signs of
mental deficits. They exhibited a significant
decline in memory, along with an increase in
compulsiveness and in anxiety-based behav-
ior compared to the CDmice.
These changes in the HFDmicemanifested
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Research Center
themselves in several ways. In one test, mice
were placed into a box containing sixteen
marbles and fresh litter, a situation that can
make them uneasy because the litter smells
differently than the mouse’s own scent. The
HFD mice displayed significantly more anx-
ious and compulsive behavior by burying
most of themarbles, while the CDmice did not
bury—onlymoved and explored—themarbles.
The movement of the mice was followed
with video tracking computer software to look
at factors such as the speed of their walking,
the amount they walked, and the pattern the
mice took inside their boxes.
These tests continued to show changes in
behavior among the HFDmice.The HFDmice
displayed decreases in exploratory behavior
by hugging the sides of their boxes as they
walked instead of scurrying all over the box—
another sign of anxiety.
“This is an instinctual move by the mice to
protect themselves from predators they may
encounter in the wild, such as owls,” Bruce-
Keller said.
Further testing revealed increased inflam-
mation in the intestines of the HFDmice, and
subsequently in their blood and brains, likely
because the unhealthymicrobiomes affected
the structural integrity of the intestines leading
to leaking and translocation of bacteria into
the bloodstream, Bruce-Keller said.
Two other observations were important to
note. First, none of the mice in either group
became obese, none had a change in insulin
levels or became insulin resistant, and none
of the mice displayed unhealthy triglyceride
levels. Second, an in-depth characterization
of the gut microbes in the two groups of mice
showed subtle, but significant differences in
the number of specific strains of bacteria.
These findings strongly suggest that it is the
difference in bacterial diversity and not the
presence of obesity or insulin resistance that
caused the changes in behavior and brain
chemistry.
“This study might serve to take the focus
off of weight as a primary indicator of health.
Just because someone is a few pounds over-
weight, that may not indicate they are neces-
sarily unhealthy,” Bruce-Keller said. “It leads
us to believe that there is increased evidence
to support the benefits of a healthy diet and
lifestyle, and we are hopeful because this is
a very flexible and realistic target for staying
healthy. In the future, these findings could pro-
vide doctors with a better way to help people
get and stay healthy.”
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