A Way to Slow Parkinson's?

Blocking Specific Form of a Brain Chemical Could Slow Brain Cell Loss, Researchers Find

By Daniel DeNoon
WebMD Medical News
http://www.webmd.com/content/article...src=RSS_PUBLIC

Sept. 12, 2006 -- Blocking a specific form of a brain chemical slows brain cell loss in an animal model of Parkinson's disease, Texas researchers report.

In the animal model, the researchers found they could slow the death of affected brain cells by about half by blocking the chemical, called soluble TNF.

The finding offers a target for new drugs that could slow the progression of the debilitating and deadly disease. And it may apply to Alzheimer's disease as well, suggest University of Texas Southwestern Medical Center researchers Melissa K. McCoy, Malú G. Tansey, PhD, and colleagues.

The finding "may unveil opportunities for development of new … therapeutics to treat human neurodegenerative diseases like Parkinson's disease and Alzheimer's disease," McCoy and colleagues say.

The researchers report their study in the Sept. 13 issue of The Journal of Neuroscience.

Parkinson's Culprit Found?

Parkinson's happens when about 80% of a specific kind of brain cell mysteriously dies off. McCoy and colleagues note that this seems to involve one of the body's most basic immune responses -- inflammation.

Messenger chemicals trigger this process. One of those chemical messengers is tumor necrosis factor, or TNF.

You may have read about TNF before. It's involved in the haywire immune responses that cause rheumatoid arthritisrheumatoid arthritis.

The UTSW researchers decided to look at a specific form of TNF called soluble TNF. That's because the kind of brain cells that die off during Parkinson's disease are highly sensitive to that brain chemical.

Sure enough, in an animal model of Parkinson's disease, they found that by blocking soluble TNF, the rate of brain cell death could be about cut in half.

That, they suggest, would be enough to significantly slow the inexorable, deadly progression of Parkinson's disease.

Current arthritisarthritis drugs Enbrel and Remicade block TNF. But they block a form of the chemical important to immune function and infection resistance.

For Parkinson's disease, McCoy and colleagues suggest a drug that specifically blocks soluble TNF would be safer.

There's also evidence from mice studies that TNF signaling may be important in Alzheimer's disease, too. McCoy and colleagues say a drug that blocks soluble TNF might kill two birds with one stone.

Blocking soluble TNF does not stop the death of important brain cells -- it only slows the process. But the researchers say this could be enough to make a major impact.

"A reduction of [brain-cell] death by 50% with delivery of [TNF-blockers] into the central nervous system would have a significant and positive impact on delaying progression of [brain cell] loss in individuals with Parkinson's disease, should these results in animal models be realized in clinical trials," they say.

SOURCES: McCoy, M. The Journal of Neuroscience, Sept. 13, 2006; vol 26.

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TNF: Tumor necrosis factor. A type of biological response modifier (a substance that can improve the body's natural response to disease). Tumor necrosis factor- (TNF-), a cytokine secreted by adipose tissue and other cells

Cytokine: Any of several regulatory proteins, such as the interleukins and lymphokines, that are released by cells of the immune system and act as intercellular mediators in the generation of an immune response.

Adipose Tissue: A type of connective tissue specialized for lipid (fat) storage.