Zebrafish as an Alternate Animal Model for Biomedical Research
Gayatri Dewangan
Department of Pharmacology and Toxicology
College of Veterinary Science and A.H., Mhow
INTRODUCTION
Many animal species play crucial roles in advancing biomedical research as experimental models. The validity and consistency of study findings from in vitro or rodent studies are enhanced by the use of animal models. Zebrafish has become a popular animal model for biomedical research. Zebrafish are employed as model organisms in nearly every area of biology worldwide. The advancements in molecular techniques throughout the latter half of the 20th century leads to use of Zebrafish as a model organism in almost all aspects of biology throughout the world. Zebrafish are becoming more and more popular as models because of their qualities that make them appropriate for a wide range of research applications. An attractive vertebrate model organism for biomedical research is the zebrafish.
What are zebrafish?
This is tropical freshwater fish belonging to the minnow family include. They can be found in India’s rivers and ponds , although these days, pet stores frequently sell them. The blue stripes that run horizontally down either side of their bodies give them the name “zebrafish.” Danio rerio the Latin name for zebrafish. Organogenesis and other developmental phases in zebrafish happen quite quickly. One of the main causes of the expansion of zebrafish research is its quick growth.
WHAT MAKES ZEBRAFISH A BETTER MODEL FOR RESEARCH ?
It is important to minimise animal suffering by using the least sentient organism possible when using animals in research. However, there are also scientific reasons why ‘lower’ organisms, such as zebrafish, can be a better model for research. Some of these reasons are given below:
- Genetic similarity to mammals
Since zebrafish are vertebrates, they are quite similar to mammals, including humans, in terms of both sequencing and function. Studies on fish can provide important insights into human illness processes because all vertebrates share similar cell biology and developmental processes. For instance, every protein that has been investigated thus far in fish and mammals has a similar purpose.
- Housing and care easier than rodents
Zebrafish are easier to keep in environments that seem more natural than it is possible to mimic for mammals because of their tiny size and the relatively simple nature of their natural habitat. This reduces housing stress and the potential effects it may have on experiment results. This not only improves the utilization of animals but also minimizes the number of animals required because it lessens the possibility of stress-related variance between subjects.
- Easy to use for Impact of any genetic mutation or drug treatment
Because zebrafish embryos and larvae are fully transparent, non-invasive imaging techniques can be used to monitor the effects of genetic alteration or pharmacological treatment. Techniques that are less invasive reduce animal suffering. Since the invasive methods are avoided, this could have an impact not only on wellbeing but also on the outcome of the experiment, the transparent nature of zebrafish larvae may also result in more accurate and reproducible results.
- Lots of offspring
There is steady supply of Zebrafish, when zebrafish is preferred for research. Compared to rats, zebrafish have significantly more progeny in each generation. Compared to the 200–300 offspring that fish produce per coupling, rodents have 5–10 offspring. Zebrafish progeny likewise grow and develop swiftly.
- Genetic modification and easier to introduce genetic changes
It is also possible to genetically modify zebrafish embryos. Humans and zebrafish have 70% of the same genes, and 84% of the genes linked to disease have a zebrafish counterpart. The whole zebrafish genome has been sequenced, and more than 140,000 genes have undergone mutations to better understand their roles in both health and development.
Because zebrafish embryos can absorb chemicals added to their water, genetic modifications can be easily induced in them using only chemical mutagens. Zebrafish can have a far higher density of mutations in their genome than rats because they can tolerate far higher concentrations of chemical mutagens.
- Maintenance
Zebrafish are very robust and easy to maintain. Their ideal conditions can be easily replicated, because they are naturally found in ponds. Although they cost a lot less than other model organisms like flies, they still need a larger room. This model is also a vertebrate, which gives it an advantage over other models.
- Reproduction
Zebrafish can lay hundreds of eggs a week due to their incredibly high fertility. Additionally, because of their extremely quick production times, scientists have an endless supply of these models. This expedites the entire experimentation process and is especially helpful when producing mutants. Zebrafish eggs develop externally, this is an another advantage over other models, such as mice which allows scientists to study their initial development easily.
APPLICATIONS OF ZEBRAFISH IN BIOMEDICAL RESEARCH
- Hematopoietic Research
Since these fishes have the same sequential multilineage hematopoiesis process as human beings, these model organisms provide many insights, both in blood lineage development pathways and blood disorders, to the scientists who are studying in the field of medicine.
- Cardiovascular Research
Given that the embryonic heart anatomy of these fish is comparable to that of human embryos, they are also frequently utilized in studies concerning cardiovascular problems. Zebrafish also benefit from the ability to live without sufficient heart circulation. Despite circulatory problems, the embryo benefits from this exceptional characteristic as it develops from the very beginning. For example, one of the ways they are used in this discipline is to investigate the connection between myocardial infarction and inflammation.
- Neurological Research
Since human brains include many of the same signaling proteins found in zebrafish brains, treating neurological problems in zebrafish is a significant area of research. In fact, many neurological disorders known to affect humans also affect zebrafish.
- Toxicity Assays for Drug Discovery Using Zebrafish
Zebrafish are highly amenable to chemical absorption through water, and their transparent ex-utero embryos make it simple to identify toxins or knockdowns that cause harm to them. Furthermore, it has been demonstrated that substances that are known to be harmful to humans and animals also have comparable effects on zebrafish.
Toxicity assays using zebrafish include:
- Developmental / embryo toxicity
- Cardiovascular toxicity
- Hepatotoxicity
- Neurotoxicity
- Nephrotoxicity
- Ocular toxicity
- Zebrafish for Pharma Research
Zebrafish are being used in early Drug Discovery investigations by pharmaceutical industry researchers all over the world. By employing zebrafish for High Content Screening of tiny molecules, researchers can produce potential medicinal compounds more quickly and economically. Treatments for neurological conditions, cancer, cardiovascular disease, infectious diseases, and a number of uncommon illnesses are among the drugs now in development.
- Zebrafish for Agrochemical Research
Zebrafish have also been used in toxicity studies related to pesticides, including herbicides, fungicides, bactericides, and insecticides in recent years. For the purpose of studying oxidative stress, developmental toxicity, and neurotoxicity, fish are usually employed at the embryonic and larval stages. 352 papers were published on the topic between 2012 and 2019, indicating a growing use of zebrafish in agrochemical research, not just for safety concerns but also for environmental toxicity.
- Aquaculture Research
Among the several fish species raised for aquaculture, zebrafish are also among the more genetically adaptable aquatic species. Commercial applications of the zebrafish model include the identification of genes involved in the development of muscles, bones, and lipids; the metabolism of nutrition; the pathophysiology of disease and stress; and behavioral features.
- Zebrafish for Cosmetic Research
There are strict regulations governing animal experimentation in the cosmetics sector. Again, zebrafish in the embryonic and early stages present a competitive option in this field. Zebrafish have demonstrated potential in a number of areas, including phenotype-based high-rate screens of skincare products (nanotoxicity). For instance, skin care treatments that lessen UV radiation-induced free radical damage are becoming more and more well-liked. A popular and useful method for evaluating these antioxidant chemicals is to test them on zebrafish larvae.
