Stress and brain

This acticle is my canadian friend send to me. My teacher always asks us to read articles from bbc.com. I am shame that I seldom read article on bbc.com. not until my friend send me this article... i don't find that some articles is very interesting and can broaden my horizons...

Why he sent me this article? maybe I always forget something. so he thought some of my brain cells killed.

He trys to find out the reason about my bad memory. Finally, he thinks it may due to the stress that i carry too much! If brain cells killed, it will never renew. Anyway, I should stop this tragedy contiuous...

Thank for XXX about sending me this article and save my remained brain cells!!! (Ah! he teaches me english sometime... )

You want to know who is XXX? Oh! it is secret... I don't want to post his name...coz it is private ! I think he doesn't want me to post his name here too!!!

Best wishes to you !!! hope you will enjoy your university life in canada!

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Stressful event kills brain cells

A single
episode of severe stress can be enough to kill off new nerve cells in the brain,
research suggests.

Rosalind Franklin University researchers believe their finding may give new
insights into the development of depression.

Working on rats, they found that cells were lost in the hippocampus, an area
of the brain which processes learning, memory and emotion.

The study features in the Journal of Neuroscience.

The researchers found that in young rats, the stress of encountering
aggressive, older rats did not stop the generation of new nerve cells in the
hippocampus.

However, it did prevent the cells from surviving - leaving fewer new neurons
for processing feelings and emotions.

The hippocampus is one of two regions of the brain that continues to develop
new nerve cells throughout life, in both rats and humans.

Treatment hope

The researchers believe the loss of cells could be one cause of depression.

However, their work also raises hope of possible treatments to stop acute
stress from contributing to mood problems.

They found that cells tended to die not immediately following a stressful
situation, but after a delay of 24 hours or more.

In principle, they argue it could eventually be possible to administer
treatment during this time to prevent cells being lost.

The researchers put each young rat in a cage with two older rats for 20
minutes.

The older rats quickly pinned down, and in many cases, bit the intruder.

The young rats had stress hormone levels six times as high as those who were
not caged with older animals.

Microscope analysis

However, microscopic analysis of brain tissue showed that their ability to
generate new cells in the hippocampus remained undimmed.

This seemed to disprove a previous theory that stress hormones put a brake on
the generation of new cells.

A week after the encounter, however, only a third of the new cells had
survived.

Long-term survival of nerve cells was also compromised.

In another part of their study, the researchers marked newborn cells in the
hippocampus, and subjected rats to stress a week later.

At the end of the month they counted a third fewer fully developed nerve
cells.

Lead researcher Dr Daniel Peterson said the next step was to understand how
stress reduced cell survival.

Mixed results

Professor David Kendall, from the University of Nottingham, said previous
research had shown that longer-term, unpredictable mild stress could depress
nerve cell generation in the hippocampus.

That study suggested the key seemed to be a reduction in production of a
hormone that helps keep brain cells alive.

However, Professor Kendall said there was also evidence to suggest that mild
stress could be protective.

"You might remember the issue of London cabbies allegedly having bigger
hippocampi related to the stress of acquiring "The Knowledge".

"The rule of thumb seems to be; a little stress is good for you but
severe/unpredictable stress is bad."