Zebrafish have the potential to be an effective animal model for neurodegenerative disease. Because
of the transparency observed in zebrafish embryos, non-invasive imaging techniques can be used to
visualise individual genes. Neurodegenerative diseases are those that affect bodily functions such as
walking, talking, breathing, as well as involuntary actions such as heartbeat and kidney function.
These diseases are most common in the elderly, but they are also common in children born
prematurely. Alzheimer’s disease (AD), Parkinson’s disease (PD), and amyotrophic lateral sclerosis
are some examples of this disease (ALS). The World Health Organization (WHO) predicts that by
2040, NDD will overtake cardiovascular disease as the second leading cause of death. More animal
models that can depict the complexities of NND pathogenesis are in high demand. Movement
disorders are a diverse group of neurological conditions marked by an inability to produce or control
Although the zebrafish (Danio rerio) has been used extensively in neurodevelopmental studies for
many years, its use in neurological disease research is relatively new. Because it is a vertebrate, this
animal has advantages over other small animals such as the fly or worm in the study of human
disease. Genetic and non-genetic disorders can be modelled in both the adult and embryonic
organisms. The embryo can be genetically manipulated to generate stable and transiently expressing
transgenic fish, as well as knock down genes to study their loss of function. Because of the large
number of offspring, screening studies are also easily performed.
Neurodegeneration is being studied using zebrafish. Other techniques for inducing neurological
models include the generation of stable transgenic lines, gamma irradiation, chemical mutagenesis,
TILLING, zinc finger nucleases, and surgery. Furthermore, in situ hybridization, behavioural testing,
electrophysiology, and pharmacological challenges can be used to characterise phenotypes that
develop in these models, in addition to the techniques described here. Despite the numerous benefits
of modelling diseases in zebrafish described here, zebrafish research is not without its drawbacks. The
disadvantage of its simplicity is that the nervous system of zebrafish is more primitive than that of
humans, and this simplification is even greater in embryos. Although the zebrafish genome is smaller
than the human genome, many human genes have multiple zebrafish orthologues due to genome
duplication during evolution.
Zebrafish have the potential to be an effective animal model for neurodegenerative disease.
Because of the transparency of zebrafish embryos, non-invasive imaging techniques can be used to
visualise individual genes (fluorescently labelled or dyed). The embryo’s transparency also aids in
genetic manipulation. Due to the small size of larvae, neuroactive compounds can also be screened
using high-throughput methods. Transient manipulation of gene activities and subsequent examination
in a normal cellular environment is very simple. Morpholine antisense oligonucleotide, mRNAs,
transgenes, and genome editing techniques such as CRISPR-Cas9, TALENS are all capable of
genetically manipulating embryos.
1) Spontaneous Coil Test (STC): The test was evaluated in terms of coil duration and coiling
frequency to determine coiling activity. The exposure time should be between 0 and 28 hpf, and the
embryo should be between 19 and 28 hpf at the time of measurement.
2) Photomotor response (PMR) test: Embryos were exposed in crystallising dishes at 26°C from 2 to
30-35 hpf. PMR measurements were then performed on embryos at this stage. Movement activity,
also known as the motion index, is recorded. The exposure time should be between 0 and 28 hpf, and
the embryo should be between 19 and 28 hpf at the time of measurement.
3) Locomotor response test (LMR): Locomotor activity recording in terms of total distance moved
and was integrated every minute for each treatment (T) and control group (C) (n = 16 embryos each).
The exposure duration should be between 0 and 120 hpf, and the embryo’s age at the time of
measurement should be between 72 and 120 hpf.
4) The alternating light- and dark-induced locomotor response test (LMR-L/D) subjects the embryo to
a 10-minute period of darkness, followed by three alternating cycles of 10-minute light and 10-minute
dark. Swimming distance, duration, and speed are all recorded. The exposure duration should be
between 0 and 120 hpf, and the embryo’s age at the time of measurement should be between 72 and
120 hpf.
Conclusion
The use of neuroactive substances in the treatment of neurodegenerative diseases should result in the
following outcomes. Similar behavioural methods resulted in a consistent behavioural response to
anticipated activity across studies (hypo- or hyperactivity), Different methods (STC, PMR, LMR,
LMR-L/D) should produce consistent anticipated activity (hypo- or hyperactivity). The observed
activity was consistent with the anticipated activity regardless of the method used. The respective
effect concentrations in the different studies are similar when hypo- or hyperactivity is consistent
across studies. Due to the clinical heterogeneity of the disease, a number of pharmacological drugs
designed for the treatment of neurodegenerative diseases have failed in clinical trials over the last
several decades. Because most NDD pathologies are genetic, disease-modifying treatments can only
be effective in the early stages of the disease.