The U.S. scientists have claimed that they have found the brain's natural antioxidant defense mechanism to protect its nerve cells from toxic free radicals.

According to the researchers at the Dana-Farber Cancer Institute, this system protects the brain cells from the harmful effects of toxic 'free radicals' that are the waste products of cell metabolism that has been associated with aging and certain degenerative brain diseases, heart attack, strokes and cancer.

"Potentially, it may be possible to use drugs to strengthen the antioxidant system in the brain as a treatment for presently incurable diseases such as Parkinson`s, Huntington`s and Alzheimer's," said the researchers.

Bruce Spiegelman and his team used a mouse model in the study. They found out that accumulation of reactive oxygen species or free radicals makes the regulatory protein, PGC-1a to switch the anti-oxidant system on.

According to some experts, the failure of the protective system is mainly responsible for some of the brain diseases. Researchers have found that high levels of PGC-1a in cultured cells offers protection against nerve toxins.

This study is to be published in the Oct. 20 issue of the journal Cell. They are at present working on compounds that would stimulate the expression of PGC-1a in brain cells.