From: gts (gts_2000@yahoo.com)
Date: Mon Nov 25 2002 - 22:19:48 MST
Scientists Identify Memory Genes
November 25, 2002 02:08:35 PM PST, HealthScout News
By Adam Marcus
HealthScoutNews Reporter
MONDAY, Nov. 25 (HealthScoutNews) -- Scientists have identified scores
of brain genes that ramp up when rats swim through water mazes,
suggesting that these instructions are involved in learning and memory.
A new study by researchers in Italy and the United States has found 140
genes, located in an area of the brain called the hippocampus, that had
significantly altered activity when rats navigate a water maze. By
enhancing the protein product of one of those genes, the scientists
significantly boosted the rodents' spatial learning ability.
Dr. Daniel Alkon, scientific director of the Blanchette Rockefeller
Neurosciences Institute in Rockville, Md., and a co-author of the paper,
said the work could one day help treat people with Alzheimer's disease.
"Alzheimer's disease at the beginning is a disease of memory. We expect
that these genes [or their human counterparts] will also be important as
early targets of Alzheimer's disease," he said.
A report on the findings appears this week in the Proceedings of the
National Academy of Sciences.
Alkon and his colleagues used "gene chip" technology to watch the DNA of
rat brains after the rodents performed a standardized behavior test
called the Morris water maze. This activity is a well-established method
of assessing spatial learning and memory, which are housed in the
hippocampus.
They also studied rats that swam untested, as well as a group that
simply hung around in their cages.
By analyzing cells in the hippocampus at various points in time, Alkon's
team was able to compare the rats' gene activity and distill that
attributable to learning.
"There are a certain number of genes that change just with physical
activity, and they have an overlap with some genes that changed with
learning," Alkon said.
The genes made the cut if their activity increased or decreased by at
least a factor of two, and if that effect was reproducible, Alkon added.
To confirm the results, the scientists also studied the proteins
generated by the genes.
The researchers classified the 140 retention genes into six major
families, the largest of which regulates signals between cells. One of
these signals is mediated by a small protein, or peptide, called
fibroblast growth factor (FGF)-18. In another experiment, Alkon's group
showed that they could improve spatial learning in rats by injecting
them with FGF-18.
Although the size of the effect was hard to quantify, Alkon said treated
animals improved their performance in the water maze by about 30 to 40
percent.
"It was not a very small, minor change," he noted.
Michael Fanselow, a psychologist at the University of California at Los
Angeles, who studies the biology of behavior, said uncovering gene
expression in the brain is key to understanding memory.
But, he added, "people have to get beyond the notion that there's going
to be a memory gene."
Instead, the process of building memories is a finely choreographed
dance between many genes, some with activity rising and others falling
quiet, he said.
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