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."