Pubdate: Wed, 02 May 2001
Source: Associated Press (Wire)
Copyright: 2001 Associated Press
Details: http://www.mapinc.org/media/27
Author: Alex Dominguez, Associated Press Writer

BRAIN CHEMICAL MAY BE KEY TO PARKINSON'S, DRUG ADDICTION, SCHIZOPHRENIA

A substance produced by the brain to help cells grow also helps a key 
chemical messenger do its job, a finding that could shed new light on 
Parkinson's disease, schizophrenia and drug addiction, researchers say.

The substance, brain-derived neurotrophic factor, has long been known to 
help brain cells mature and survive. The researchers found that BDNF also 
helps the messenger dopamine by providing a pathway used to deliver the 
message.

The findings are reported in Thursday's issue of the journal Nature by 
Pierre Sokoloff of INSERM, the French equivalent of the National Institutes 
of Health, and colleagues in Paris and Marseille, France.

Working in mice, the scientists found that BDNF prompts brain cells to 
produce so-called D3 receptors, one type of the tiny structures to which 
dopamine binds to deliver its message. So, BDNF may play some role in 
several conditions involving the dopamine signaling system, such as 
Parkinson's disease and drug addiction, researchers said.

Brain autopsies of schizophrenia patients have also found higher than 
normal levels of BDNF, Sokoloff said.

The researchers found that mice lacking BDNF had unusually few D3 
receptors. They also found that when they reduced the population of D3 
receptors in one part of the brain by chemical injection, they could 
largely restore the population by injecting BDNF.

In a commentary accompanying the paper, Francis J. White of the Chicago 
Medical School said substances that bind D3 receptors are effective at 
treating Parkinson's and reducing cocaine-seeking behavior in animal 
versions of cocaine addiction. As a result, BDNF may be involved in the 
effects of the Parkinson's medicine levodopa and in drug addiction, he said.

Ira B. Black, chairman of the department of neuroscience and cell biology 
at Robert Wood Johnson Medical School in Piscataway, N.J., said new 
treatments based on the research may be a way off.

"We don't understand enough yet," Black said. "But the important thing here 
is that the link has been established between BDNF and dopamine, and that's 
an honest day's work."
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