快猫短视频

EXPOSURE to low levels of the pesticide rotenone makes monkeys develop Parkinson鈥檚 disease, suggesting it has the same effect on people too.

鈥淚t provides proof of the concept that a lifetime of exposure to certain toxins can result in Parkinson鈥檚 disease,鈥� says Timothy Greenamyre of Emory University in Atlanta, Georgia, whose team carried out the work.

The cause of Parkinson鈥檚 has long been elusive. Only a small fraction of cases are inherited. The best evidence that certain chemicals can cause the disease came when a substance called MPTP caused a cluster of cases among San Francisco drug users in the 1980s. But this could have been an exception.

Then four years ago Greenamyre鈥檚 work hit the headlines when his team reported that rats exposed to rotenone develop Parkinson鈥檚 (快猫短视频, 11 November 2000, p 16). Rotenone is a natural insecticide still occasionally used by organic farmers and found in some garden products.

Now his team has shown that monkeys exposed to low levels of the pesticide for about 18 months develop Parkinson鈥檚. 鈥淭here is a selective neurodegeneration of the same systems that degenerate in Parkinson鈥檚 disease,鈥� Greenamyre told the Society for Neuroscience meeting in San Diego last week. 鈥淭hey have all the pathological hallmarks of the disease.鈥�

It is likely that stress, genetic predispositions and environmental toxins such as rotenone all play a role, says Michael Zigmond of the University of Pittsburgh. But he also has good news: he has shown that exercise has a protective effect. When his team injected the neurotoxin 6-hydroxydopamine into rats, only those forced to exercise did not develop Parkinson鈥檚 symptoms.

A small pilot trial involving 21 people with the disease has already begun in Pittsburg, but Zigmond cautions that too much exercise might be damaging rather than helpful.