Zebrafish Developmental Neurotoxicity Assays

In the majority of cases, the developing brain is more sensitive to chemical toxicants than the adult brain. Exposure to different chemicals during development induces a major risk to human health and can lead to the onset of different neurological and neuropsychiatric impairments, ranging from attention deficit hyperactivity disorder to autism spectrum disorders, and Parkinson's disease. The impairments observed in these diseases represent a continuum, from typical clinical syndromes at one extreme to small subclinical deficits in motor, sensory, and behavioral impairments at the other. Overt toxicity is identified relatively rarely and is usually the result of high-level exposure. However, developmental neurotoxicity testing (DNT) researches face the challenge of assessing subtle effects caused by chemicals present at relatively low concentrations.

The little progress in identifying the DNT of chemicals is in part owing to the limitation of studies using conventional in vivo models, of which experiments are laborious and time-consuming. Therefore, the zebrafish model system has emerged as a suitable complementary in vivo DNT model. The embryonic developmental stages of zebrafish are well documented, which provides a guide for us to identify major physiological alterations occurring during developmental toxicity assays. Zebrafish also exhibit many simple and complex neurobehaviors, including spontaneous swimming, startle responses, and learning. Besides, there is continuous progress on uncovering the developmental processes of the blood-brain-barrier (BBB) and central nervous system (CNS) of the zebrafish. The overall development of the zebrafish CNS and patterning of brain sub-regions are completed within three days after fertilization. The rapid CNS development combined with the general advantages of the zebrafish model system allows screening of chemical compounds for potential DNT, leading to the zebrafish being an ideal complementary model for DNT studies.

Figure 1. Zebrafish neurodevelopment. (Lee J, Freeman J L. 2014)

Our Developmental Neurotoxicity Assessment in Zebrafish

With years of experience and advanced technologies, Creative Biogene has developed several approaches to utilize zebrafish in neurotoxicity screening. Effects of different chemicals on brain development can be evaluated by different neurotoxicity endpoints including gene expression patterns, toxicokinetics, neural morphogenesis and neurobehavioral profiling. These endpoints enable the researcher to capitalize on the positive aspects of DNT using zebrafish.

• Gene expression profiling

The modulation of gene expression by exposure to chemicals at sub-toxic concentrations can be detected in zebrafish without observable phenotypic changes. Thus, defining a set of markers related to developmental neurotoxicity and quantifying the expression of these markers can be a rapid and sensitive means of conducting DNT.

• Toxicokinetics

Following the xenobiotic exposure period, embryos or larvae are collected and digested for analytical assessment. Uptake, biotransformation, and elimination can be studied by various spectrometry methods, depending on the xenobiotic of interest and sample nature.

• Neuroimaging

Morphometric endpoints can be explored by using whole-mount immunostaining with neuron-specific antibodies.

• Neurobehavioral profiling

Various neurobehaviors of larval zebrafish can be tracked in 96-well plates by using automated and video-tracking systems. These tracking systems, coupled with the ease of obtaining large numbers of zebrafish larvae, make it possible to undertake an objective and systematic analysis of behaviors.

Our Advantages

• Wide ranges of detection technologies
• Easy and flexible workflow
• Advanced high-content screening equipment
• Excellent predictability

Contact us to learn more about our developmental neurotoxicity assessment services.

References

1. Kiper K G, Freeman J L. Zebrafish as a Tool to Assess Developmental Neurotoxicity. Cell Culture Techniques. Humana, New York, NY, 2019: 169-193.
2. Lee J, Freeman J L. Zebrafish as a model for developmental neurotoxicity assessment: the application of the zebrafish in defining the effects of arsenic, methylmercury, or lead on early neurodevelopment. Toxics, 2014, 2(3): 464-495.
3. Nishimura Y, et al. Zebrafish as a systems toxicology model for developmental neurotoxicity testing. Congenital anomalies, 2015, 55(1): 1-16.
4. d'Amora M, Giordani S. The utility of zebrafish as a model for screening developmental neurotoxicity. Frontiers in neuroscience, 2018, 12: 976.

For research use only. Not intended for any clinical use.