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Parkinson's clue

点击量:   时间:2019-03-07 09:13:06

By Michael Day TO FIGHT Parkinson’s disease, drugs that block the production of toxic nitrogen oxides must be developed, neurobiologists say. Such medicines should actually prevent symptoms, whereas existing drugs only treat them. Clues that nitrogen oxides play a role came in the early 1980s, when drug abusers in California had been experimenting with injecting a drug related to morphine known as MPTP. They soon developed symptoms similar to Parkinson’s disease, such as tremors. As a result, animals treated with MPTP have become a popular model for the disease. Neurobiologists led by Gabriel Liberatore of Columbia University in New York have shown that injecting mice with MPTP increases the activity of an enzyme in the brain called inducible nitric oxide synthase (iNOS), which produces nitric oxide. This is accompanied by a rise in the death rate of nerve cells that make dopamine, a key neurotransmitter. The researchers think the increased activity of iNOS raises levels of nitric oxide, which in turn produces more powerful oxidising agents that kill the dopamine-producing neurons. Lowered production of dopamine is thought to underlie Parkinson’s disease. The team also showed that mutant mice lacking genes for iNOS were much more resistant to the effects of MPTP. So it’s possible that drugs that block iNOS’s effects would help treat Parkinson’s. “We hope to develop drugs that slow down the disease and give people a long window before they go onto drugs which have side effects and only work for a limited time,” says team member Valina Dawson of Johns Hopkins University in Baltimore. Thomas Grunewald, a Parkinson’s researcher at Cornell University, thinks this result is important. He adds that treatments for the disease will probably also have to include drugs that neutralise free radicals,