Brain drug gives new hope to Parkinson's sufferers

Published on Wednesday 5 July 2006 01:14

THE effects of Parkinson's disease could be reversed by a drug which causes new brain cells to grow, research suggests.

Scientists hope that the findings from the experimental drug could lead to new treatments for patients with the debilitating disease.

There are currently no proven treatments to slow or halt the course of Parkinson's disease, which affects 10,000 people in Scotland, with drugs becoming less effective over time.

The progressive disease's symptoms of tremors, stiffness in the limbs, slow movements and poor balance and co-ordination are caused by the loss of neurons in the brain.

Now new tests in animals show that a drug, known as 7-OH-DPAT, which mimics the effects of the nerve-signalling chemical dopamine, causes new neurons to develop in the part of the brain where cells are lost to the disease.

The team from the Mayo Clinic College of Medicine in Florida gave the drug to rats with symptoms similar to Parkinson's in humans.

The rats were also given infusions of a fluorescent substance to show how neurons in the brain were connecting. They were tested before and after receiving the treatment to see how well they could walk and move.

Animals treated with the drug had more than twice as many multiplying cells as those who did not receive treatment.

Many of these new cells appeared to develop into mature neurons and about 28 per cent appeared to be the key dopamine neurons. There was also an 80 per cent improvement in movement and the rats' ability to retrieve food by themselves after treatment.

The researchers, writing in The Journal of Neuroscience, said that the effects appeared to last at least four months after treatment ended.

Lead researcher Dr Christopher Eckman said: "There was a profound behavioural effect of the treatment, even after it 'washed out' of the system. This shows that the treatment affects the underlying pathology."

The experimental animal drug is similar to others currently approved to treat Parkinson's in humans.

Dr Eckman said while these were useful in treating the symptoms, they had not been designed to prompt new neurons to grow.

He said that tweaking how these drugs work or developing new compounds to boost neuron growth could provide an entirely new way of treating Parkinson's.

Dr Eckman said this was the first study to show that the development of new neurons from cells already in the brain could lead to better movement in those treated.

The findings may also lead to new ways of treating other degenerative diseases affecting the brain, such as Alzheimer's.

Many researchers are currently trying to find ways of replacing lost neurons in Parkinson's disease.

One possible way that this could be achieved would be to transplant new neurons grown from embryonic stem cells or other cells.

But this type of treatment is very difficult for technical reasons. There is also some ethical concerns about the use of embryonic stem cells, which are harvested from human embryos which are then destroyed.

Dr Eckman said that a drug therapy would be much easier to give to patients with Parkinson's.

The researchers are now looking at how different doses of existing Parkinson's drugs affect the development of new cells. They hope to then be able to test comparable doses in humans.

The National Institute of Neurological Disorders and Stroke in the US described the research as "very exciting".

Dr Kieran Breen, the director of research at the Parkinson's Disease Society in the UK, said: "The results of this study are interesting, demonstrating this drug has a positive effect on both stem cells within the brain and the growth of neurons and can lead to improved movement in rats with Parkinson's.

"As the drug tested in the trial has similar effects to dopamine agonists - a class of drugs currently used in Parkinson's treatment - further studies are required to see if these currently available treatments have a similar effect on stem cells within the brain and the growth of neurons."

Dr Breen said the research helped further understanding of Parkinson's.