Parkinson's treatment hope

Behind the Headlines

Monday July 16 2007

Parkinson's brain scan picture

A Parkinson's CT brain scan

Hope for a new therapy that may slow or even reverse the symptoms of Parkinson’s disease was reported by BBC News on July 14 2007. The article reported the discovery of a protein (conserved dopamine neurotrophic factor, or CDNF) that when used in rats appeared to slow and even reverse Parkinson’s-like disease. The implications of the story are that the protein may have the same effect of halting and reversing the destruction of dopamine-producing nerve cells in the brain that leads to Parkinson’s disease in humans.

The news story described how experiments were carried out on rats with chemically induced Parkinson’s-like disease. The disease state aimed to simulate an advanced stage of Parkinson’s disease in humans to see if the protein could help repair damage in nerve cells.

The report also mentioned previous research based on another protein (glial-cell-line-derived neurotrophic factor [GDNF]) which had previously been shown to improve Parkinson’s symptoms, but further studies had raised issues over its effect and safety.

The study compares the effect of CDNF, GDNF and a placebo in rats with a Parkinson’s-like disease. Animal studies cannot automatically be applied to humans, and Parkinson’s-like disease is not the same as actual Parkinson’s.

Ultimately, studies need to be carried out on humans before we can draw conclusions about the effects of CDNF on Parkinson’s disease.

Where did the story come from?

The story was based on a study in rats conducted in a laboratory by Mart Saarma and a research team from the University of Helsinki, Finland, and published in letter form in the peer-reviewed medical journal Nature.

 

 

What kind of scientific study was this?

There were two relevant parts to the study. The first assessed the protective effects that the proteins have on rat brains.The rats were pretreated with either CDNF, a placebo or GDNF glial-cell-line-derived neurotrophic factor another protein which had previously been shown to improve Parkinson’s symptoms, though further studies had raised issues over its effect and safety. Six hours after the pre-treatment, a Parkinson’s-like disease was chemically induced in the rats and their response to the treatment was assessed.

 

The second part of the study assessed the curative effects that the proteins had on rat brains.The disease was induced in rats four weeks before they were treated with CDNF, GDNF or a placebo.The effect of the proteins in their brain was compared 12 weeks after treatment.

 

What were the results of the study?

For the protective part of the study, the researchers found rats pre-treated with CDNF displayed reduced behavioural symptoms associated with the disease when tested at both two and four weeks after treatment. In rats treated with GDNF, behavioural improvements were only seen at two weeks.

 

The curative part of the study found that CDNF improved behavioural symptoms of the disease in rats, and restored the dopaminergic neurones compared with a placebo 12 weeks after treatment.

The process between an initial positive result in an animal study and final approval for use in humans can take many years.

 

What the researchers say

The researchers report that CDNF appears to protect the dopaminergic neurones from Parkinson’s-like disease in rats.

 

CDNF reduced the behavioural symptoms of the disease in rats, prevented degeneration of dopaminergic neurons and restored dopaminergic function.

The researchers conclude that “CDNF might be beneficial for the treatment of Parkinson’s disease”.

 

What does the NHS Knowledge Service make of this study?

Parkinson’s disease is thought to be caused by a deficiency of the chemical transmitter dopamine in specific parts of the brain. As this study was conducted in animals, the findings cannot automatically be applied to humans.

 

Rats were exposed to toxins that are believed to cause Parkinson’s-like disease because of their effects on dopaminergic neurones and behaviour. These disease models are not exactly the same as Parkinson’s in humans.

The research appears to be well-conducted, and the researchers used comparison groups of animals to see how another treatment or no treatment compared.

Ultimately, studies need to be carried out on humans before we can draw conclusions about the effects of CDNF on Parkinson’s disease.

It has been estimated that very few – five in 5,000 – chemicals that are tested in the laboratory and on animals ever make it to human studies, and only one of those five may be safe and effective enough to reach pharmacy shelves. The process between an initial positive result in an animal study and final approval for use in humans can take many years.

Analysis by Bazian

Edited by NHS Choices

Links to the headlines

Hope for new Parkinson's therapy. BBC News, July 14 2007

Links to the science

Chan C, Guzman J, Ilijic E, et al. 'Rejuvenation' protects neurons in mouse models of Parkinson's disease. Nature 2007; 447:1081

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