Animal experimentation is debated. Is scientific research ready to do without animals? Are alternatives sufficient? Colin Deransart, Bertrand Favier, Sabrina Boulet and Véronique Coizet from Grenoble Alpes University take the example of Parkinson’s disease. Here is a short version of their article published on our site on April 28, 2025
Regularly criticized, animal experimentation remains necessary to improve our knowledge on certain pathologies. For example Parkinson’s disease, which affects more than 270,000 people in France. Its diagnosis is often made too late to consider curative treatments.
Our team works to identify early markers of the disease. The stake, in the long term, is to be able to take care of patients before the damage is irreversible. Animal experimentation then makes it possible to complete the data obtained in humans.
In 1959, the Biologists William Russel and Rex Burch proposed the “3 R rule” to supervise the ethics of animal experimentation: replace, when possible, the use of animals by alternative models, reduce the number of animals required and finally refine experiments to minimize the constraints imposed on animals (pain, suffering, anxiety …).
In our research, we use three distinct animal models: two on the rat and one on the macaque. This may seem contrary to the last rule, but it makes it possible to cross -check data and increase their transposability to humans. The first thus focused on rats treated by a neurotoxin targeting neurons producing dopamine. The second was interested in the production of a deleterious protein, in order to study the progressive nature of the disease. In the third an injection of neurotoxin made it possible to reproduce the evolution of the clinical phases of the disease, with greater homology with humans.
Each animal model thus reproduces a precise stage of the disease and of course constitutes a simplification. This made it possible to identify six metabolites potentially linked to the neurodegenerative process. By combining them, a composite metabolic biomarker is obtained. By looking for it in recently diagnosed but not treated patients, it is noted that it can distinguish them from healthy patients. The key, the prospect of better following the evolution of the disease in a less restrictive way than the methods of current medical imaging, and a therapeutic hope: the deregulation of several of these metabolites could be partially corrected by a drug mimicking the effects of dopamine.
Beyond these advances, the detractors of animal experimentation often highlight the low transposition of the results of the animal to humans to justify the exclusive use of in vitro or in silico (digital) models. However, it has not been shown that the transposition of these tests is better in the current state of techniques. They are in reality the first screenwriters of all preclinical tests, while the contribution of animals at the end of the preclinical phase makes it possible to exclude 40 % of candidates medication, in particular on the basis of risks in humans. This guarantees quality care.
And that with a limited impact: it is estimated that during his life, an average Frenchman will “consume” only 2.6 laboratory animals, to compare to the 1298 animals consumed to eat.
This text is the short version of the article written by Colin Deransart, Bertrand Favier, Sabrina Boulet and Véronique Coizet of Grenoble Alpes University
