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[novapsyche]

Bullied Mice Show Brain Reacts to Stress

Any bully's victim knows the experience can cause lingering fear. Now scientists watching big mice intimidate small ones have discovered the stress spurs genetic changes in the brain — a finding that may help research into depression and other mental illnesses.

The experiment suggests a part of the brain linked to addiction also plays a previously unsuspected role in illnesses characterized by chronic anxiety and social withdrawal, Texas researchers report Thursday in the journal Science.

In fact, a substance produced in the brain, called BDNF, seems to be the culprit, controlling whether the bullied mice turned into fearful hermits or not.

[...] BDNF is a chemical important for the growth and maturation of nerve cells. Some antidepressants are thought to increase BDNF levels in the hippocampus, helpfully boosting neurons.

But in this different brain region, encompassing the so-called mesolimbic dopamine pathway, Dr. Eric Nestler, UT Southwestern's psychiatry chairman, found too much BDNF was bad: The bullied mice experienced marked BDNF increases, which in turn switched on several hundred genes located deep in the front part of the brain. That unusual gene activation paralleled the animals' social withdrawal.

Then Nestler's team injected mice with a virus that switched off BDNF production only in this one brain region, and repeated the bullying experiment. Mice lacking the BDNF didn't become cowed — they essentially couldn't learn how to respond to this emotional threat, evidence of BDNF's role in social stress.

Comments

[kittenkissies.livejournal.com]

We need to find this mouse bully and counsel him before it gets worse.