Putting the move on primate Parkinson's.

Putting the move on primate Parkinson's

Preliminary research indicates a new surgical technique eases the symptoms of a Parkinson's-like disease in monkeys and adds to evidence suggesting at least two areas of the brain play a crucial role in this debilitating movement disorder. If confirmed, the new finding may lead to more effective treatment for persons with the disorder, especially those resistant to drug therapy.

Parkinson's disease develops when an as-yet-unknown process destroys certain dopamine-producing neurons in the brain's substantia nigra. Some researchers have hypothesized that this process somehow affects another brain region known as the subthalamic nucleus, causing its neurons to fire too rapidly and thus producing the muscular tremors and rigidity that plague Parkinson's patients. A study reported in the Sept. 21 SCIENCE now provides the first direct evidence linking Parkinsonism's movement movement difficulties with the subthalamic nucleus.

Mahlon R. DeLong, then at the Johns Hopkins Hospital in Baltimore, and his colleagues gave two African green monkeys intramuscular injections of MPTP, a synthetic drug known to cause a primate disorder that resembles human Parkinson's symptoms. A week after receiving the injections, the monkeys sat largely motionless in their cages, unable to feed or groom themselves.

When the monkeys had developed a severe and stable form of the disease, the team injected a neurotoxin called ibotenic acid directly into the subthalamic nucleus of each animal's brain. The treatment brought a "dramatic improvement," DeLong told SCIENCE NEWS. Within minutes, he says, both monkeys moved about their cages and resumed feeding and grooming.

These findings hint that the disease's crippling effects result from neural overactivity in the subthalamic nucleus, says DeLong, now at Emory University in Atlanta. The ibotenic acid destroyed some neurons in that region of the monkey brains, slowing the neuron-firing rate, he speculates.

Scientists don't understand the function of the subthalamic nucleus in normal individuals, but suspect it is involved in movement regulation. By learning more about the subthalamic nucleus and Parkinson's disease, investigators may unravel the mystery of the healthy subthalamic nucleus and glean clues about other movement disorders such as Huntington's disease, comments Peter L. Strick of the State University of New York Health Science Center at Syracuse.

"This is a fantastic report," says Edward H. Oldfield of the National Institute of Neurological Disorders and Stroke in Bethesda, Md. While DeLong predicts the new treatment may benefit at least that third of Parkinson's sufferers who can't take the drug L-dopa, a natural precursor to dopamine, Oldfield believes it may eventually prove useful for all Parkinson's patients. However, before investigators attempt the potentially risky technique on people, more research must confirm these new findings.