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Basic research into Parkinson's

May 07, 2004

Parkinson's disease was first described in 1817 by the London physician James Parkinson. A great amount of research has been carried out since that time but the fundamental causes of the disease remain unresolved. Some time ago now researchers found that a neurotransmitter, dopamine, played a key role in this illness. This is why the majority of treatments used today to counter Parkinson's increase the level of dopamine in the brain exciting the receptors of this neurotransmitter.

Animal models

Parkinson's disease affects certain concrete cerebral nuclei in the human brain. These nuclei are the striated and the dark matter, nuclei which are related to the motor system. Parkinson's disease specifically affects those neurones located between these cerebral nuclei.

So, when animals are used as models in order to analyse the illness, rats for example, lesions appear precisely at the location of these cerebral nuclei. The procedure involves introducing a toxic substance into specific co-ordinates of the rat's brain, but only into one hemisphere thereof, the other remaining as a control or reference. In other words, so that the Parkinson's is generated solely on one side of the animal's brain.

Once the animal has recovered from the operation, after approximately one month, the analyses can begin. On the one hand, the behaviour of the animal is studied and analysed - the visible, external effects and, on the other, the effects of medication. In order to analyse the effects of the medication habitually used to treat the ailment, these medicines are administered and subsequently the electro-physiological activity of the brain is measured, i.e. the activity of the neurones. In this way it is intended to discover the medication most suitable to stop the progress of the disease.

Mild Parkinson's

By the time Parkinson's symptoms appear in humans, cerebral lesions are quite serious and the disease passed the point of no return. However, apparently, if the disease is managed to be detected at the early stages and applying a neurone protection treatment, the illness can be halted.

But, in this case, the validity of the medicines used presently is called into question. For example, the effects that the currently most commonly used treatment, levodopa. That is, it is not clear whether levodopa administered in the early stages of Parkinson's is neuroprotector or neurotoxic. To this end, in order to analyse, amongst other factors, the effects that levodopa produce in the early stages of Parkinson's, a model of mild Parkinson's has been developed at the Leioa campus of the University of the Basque Country.

Obtaining rats with mild Parkinson's is no easy task, given that the exact dose of the toxic substance has to be injected into the animal brain. Once a rat with mild Parkinson's has been obtained, the usual medicines are administered and the animal monitored to see if there is a differentiated evolution in the disease or not. Thus, according the Leioa investigation, the effect of the medication is totally different depending if the rat is healthy, if it has mild Parkinson's, or if the disease is advanced.

So, definite conclusions have yet to drawn, Moreover, in the case of Parkinson's, soon we will have to start dealing with gene therapy or therapeutic cloning, given that these are the future paths to follow in order to counter the disease, according to the experts.

Elhuyar Fundazioa