Pharma news

LONDON:
Experiments on mice conducted by Emory University researchers have revealed that
a protein required for the earliest steps in embryonic development,
beta-catenin, also plays a key role in solidifying fear memories in the
brain.

Study leader Kerry
Ressler, associate professor of psychiatry and behavioural sciences at Emory
University School of Medicine, says that beta-catenin can be a potential target
for drugs to enhance or interfere with memory formation.

Ressler and his graduate
student Kimberly Maguschak used a variety of approaches to probe beta-catenin’s
role in fear memory formation - such as stabilizing the protein with a pulse of
the psychiatric drug lithium, and injecting a virus that could remove the gene
for beta-catenin from brain
cells.

The researchers made
mice learn to dread a certain tone that was followed by an electrical shock, and
the animals would show that fear by freezing. “We found that after beta-catenin
is taken out, the mice can still learn to fear the shocks. But two days later,
their fear doesn’t seem to be retained because they spend half as much time
freezing in response to the tone,” Nature magazine quoted Maguschak as saying.

She said that beta-catenin
appeared to be turned on in the amygdala - a brain region thought to be
important for forming memories of emotionally charged events - and involved in
signalling during the learning process.

“However, after the process of
moving memories from short-term to long-term is complete, beta-catenin doesn’t
appear to be necessary anymore,” she said.

“Injecting the virus after
that point has no effect on the ability of the mice to express their fear
memory,” she added.

The
researchers also observed that lithium salts, when given to the mice before
training, made them even more afraid of the tone two days later. Chemically,
lithium inhibits an enzyme that usually targets beta-catenin for destruction,
causing beta-catenin to become more active.

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