The zebrafish: a multifaceted tool for research
Zebrafish are highlighted as an effective performance model to bridge the gap between cells and mammals. There are numerous advantages to the use of this model for screening new compounds:
- A higher number of samples can be processed in a shorter time
- Results can be obtained in less time
- The information content is higher than with in vitro screening, as this is done with organisms rather than isolated cells
Zebrafish are widely used in scientific research for their genetic homology with humans (> 75% of the genome share). Such a high degree of homology between zebrafish and human genotypes enables detailed study of some ailments, including but not limited to bacterial infections, heart diseases, cancer, Alzheimer’s, muscular dystrophy, etc.
The costs of keeping zebrafish are significantly lower than those of keeping mice. Zebrafish cost €0.05 a day to maintain compared to €1.00 for five mice in cage. While there are numerous individual factors that may affect these calculations in every organizations, zebrafish appear, in general, to be more cost-effective than other animals. For example, in vivo imaging of embryonic rodents is a much more intensive and costly process and its presents its own limitations.
In their early development stage, zebrafish larvae can be maintained in fluid volumes as low as 100 µl and arrayed in multi well plates. This allows for compound to be added directly to the solution in which embryos develop, the simplifying drug administration, decreasing the amount of compound used (µg-mg vs g in mice) and enabling rapid in vivo screening of these compounds.
For a drug to be effective, it must reach its intended target and confer therapeutical benefit without causing unacceptable toxicities. Consequently, ensuring good absorption, distribution, metabolism, excretion, and toxicity (ADME-Tox) is crucial to a drug’s success. Their high genetic homology with humans and their high correlation with mammals like mice (> 98%), make zebrafish an excellent model to evaluate ADME-Tox properties.
Principles for the more ethical use of animals in testing impose new restrictions on animals used for experimentation, such as replacement, reduction and refinement. From the point of view of the “3R”, zebrafish can be used to replace the so-called higher vertebrates (e.g. mice, rats) with a less evolve organism. Most of the experiments are performed on embryos or larvae whose nervous system is not fully developed and are hence not classified as protected animals.