Jetting half way across the world, shift
work and those crazy all-nighters are all
things that can upset our body’s daily
cycle, or circadian rhythm . Over the
years, scientists have slowly been piecing
together the components of our “biological
clocks” that drive these rhythms, and we
now have a pretty good understanding of
how they are coordinated.
Now, scientists have discovered what is
effectively a “reset button ” in mice, which
could eventually help researchers develop
novel treatments that correct mismatches
between the environment and our
internal body clocks.
Circadian rhythms are physiological,
mental and behavioral changes that follow
an approximately 24-hour cycle, which are
primarily dictated by changes in light in
the environment. These oscillations are
driven by groups of interacting molecules
in the body which are collectively known
as biological clocks, and it is the job of a
master pacemaker located in the brain to
coordinate and regulate these clocks to
make sure the body is in sync.
It's been known for some time that this
“master clock” is a bundle of neurons in a
region called the suprachaismatic nucleus
(SCN); however, scientists didn't know
whether altering the way that these cells
fire could change how it operates.
Now, researchers from Vanderbilt
University have demonstrated that it is
indeed possible to control the clock by
selectively switching on and off this
population of cells, which effectively
mimics their daytime and nighttime
activity.
In order to manipulate the activity of
these neurons, the researchers used a
sophisticated technique known as
optogenetics. This involves inserting
genes that code for light-sensitive proteins
into distinct populations of cells, creating
a bundle of neurons that now respond to
light in a certain way. Then, after
implanting an optical fiber into the brain,
scientists can use lasers to either
stimulate (switch on) or inhibit (switch
off) these cells.
As described in Nature Neuroscience , the
researchers found that by artificially
stimulating the SCN neurons, they were
able to manipulate the mouse's sleep/
wake rhythms, effectively resetting the
master clock. This was particularly
interesting because previous work
suggested that the firing activity of these
cells was only an output of the clock's
activity.
”Of course, this exact approach isn't
ready for human use yet,” said study
author Michael Tackenberg. “But others
are making progress toward eventually
using optogenetics as therapy.”
Tackenberg is now taking the work
forward by examining whether mice
suffering from seasonal affective disorder
—a type of depression that has a seasonal
pattern—respond to the stimulation.
This article originally appeared at IFL
Science . Copyright 2015. To Nelsino
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