March 17, 2016
The human brain has a prodigious demand for energy -- 20 to 30%
of the body's energy budget. In the course of normal aging, in people with
neurodegenerative diseases or mental disorders, or in periods of physiological stress, the supply of sugars to the brain
may be reduced. This leads to a reduction in the brain's energy reserves, which
in turn can lead to cognitive decline and loss of memory.
But new research on mice shows that the brain's energy reserves
can be increased with a daily dose of pyruvate, a small energy-rich molecule
that sits at the hub of most of the energy pathways inside the cell. These
results need to be replicated in human subjects, but could ultimately lead to
clinical applications.
"In our new study, we show that long-term dietary
supplementation with pyruvate increases the energy reserves in the brain, at
least in mice, in the form of the molecules glycogen, creatine and lactate,"
says lead author Heikki Tanila, Professor of Molecular Neurobiology at the A.
I. Virtanen Institute of the University of Eastern Finland.
What's more, dietary supplementation with pyruvate didn't only
increase the brain's energy stores: it also changed the behavior of the mice in
positive ways, show the researchers.
"The mice became more energetic and increased their
explorative activity. It appears that these behavioral changes are directly due
to the effect of pyruvate on brain function, since we didn't find that these
mice had developed greater muscle force or endurance," says Tanila.
For example, chronic supplementation with pyruvate facilitated
the spatial learning of middle-aged (6- to 12-months-old) mice, made them more
interested in the odor of unfamiliar mice, and stimulated them to perform
so-called "rearing", an exploratory behavior where mice stand on
their hind legs and investigate their surroundings.
The dose necessary to achieve these effects was about 800 mg
pyruvate per day - which corresponds to about 10 g per day in humans -- given
to the mice in normal chow over a period of 2.5 to 6 months. A single large
dose of pyruvate injected directly into the blood stream had no detectable
effect.
Interestingly, the positive response to dietary supplementation
with pyruvate was also found in a strain of transgenic mice called
APPswe/PS1dE9, often used as an animal model for the study of Alzheimer's disease. These mice exhibit
many of the same symptoms as people with Alzheimer's, such as the deposition of
protein plaques in the brain, neurodegeneration, and cognitive decline. These
results raise hopes that pyruvate might also benefit people with
neurodegenerative disorders such as Alzheimer's and Parkinson's.
"Pyruvate supplementation may prove beneficial as an
activating treatment for the elderly and in therapies for alleviating cognitive
decline due to aging, neurodegenerative disease, or mental disorders. It is
well tolerated and warrants further studies in humans," says Tanila.
The study, which was supported by the Alzheimer Association, is
published in the open-access journal Frontiers in Aging Neuroscience.
http://www.medicalnewstoday.com/releases/308013.php?tw
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