Brain chemical may be key to Parkinson's, drug addiction, schizophrenia

<br>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,

Wednesday, May 2nd 2001, 12:00 am

By: News On 6

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.''