Zebrafish Pain New Frontier Laboratory Animal Science

Zebrafish (Danio rerio) have emerged as a significant model organism in
laboratory animal science, particularly in the study of pain and
nociception. Their genetic tractability, similar physiology to humans,
and cost-effectiveness make them an ideal candidate for pain research,
offering insights that are both evolutionary and translational (Costa et
al., 2021; Ohnesorge et al., 2021).

Understanding Pain in Zebrafish

Research has established that zebrafish can experience pain, as
evidenced by behavioral changes such as reduced activity and altered
space use following tissue damage (Sneddon et al., 2023). These
behavioral indicators are crucial for assessing pain and the
effectiveness of analgesic interventions. The Fish Behaviour Index
(FBI), an automated monitoring system, has been developed to detect
subtle behavioral changes in zebrafish post-procedure, allowing for
timely pain management interventions (Deakin et al., 2019).

Stress and Pain Modulation

The state of stress in zebrafish prior to painful stimuli can
significantly alter their pain response. Acute stress has been shown to
induce analgesia, while chronic stress may lead to heightened pain
sensitivity. This stress-induced analgesia is mediated by opioid
signaling, as demonstrated by the reversal of analgesic effects with
naloxone administration (Thomson et al., 2020). Understanding these
mechanisms is vital for refining experimental procedures and improving
animal welfare.

Advancements in Pain Research

Zebrafish models have been instrumental in exploring the molecular and
physiological responses to various noxious stimuli, such as acetic acid
and formalin. These models help in understanding the complex interplay
between pain and mood disorders and facilitate the screening of
potential analgesic therapies (Costa et al., 2021). Moreover, zebrafish
have been used to study pain induced by extreme thermal stimuli,
providing insights into the conservation of pain mechanisms across
species (Malafoglia et al., 2014).

Ethical Considerations and the 3Rs

The welfare of zebrafish in laboratory settings is increasingly
recognized, with efforts to apply the 3Rs (Replacement, Reduction, and
Refinement) in research practices. This includes the development of
non-invasive methods and the use of analgesics to minimize pain during
experiments (Sabrautzki et al., 2021; Message & Greenhough, 2019). The
adoption of these practices not only enhances the ethical standards of
research but also improves the reliability of experimental outcomes.

Conclusion

Zebrafish offer a promising avenue for pain research, bridging gaps
between basic science and clinical applications. By understanding and
managing pain in zebrafish, researchers can refine experimental
procedures, improve animal welfare, and advance the development of new
pain therapies. As the field progresses, zebrafish will continue to play
a pivotal role in unraveling the complexities of pain and its management
in laboratory settings.

References

Sneddon, L., Schroeder, P., Roque, A., Finger-Baier, K., Fleming, A.,
Tinman, S., & Collet, B. (2023). Pain management in zebrafish.
Laboratory Animals, 58, 261 – 276.

Costa, F., Rosa, L., Quadros, V., De Abreu, M., Santos, A., Sneddon, L.,
Kalueff, A., & Rosemberg, D. (2021). The Use of Zebrafish as a
Non-traditional Model Organism in Translational Pain Research: The
Knowns and the Unknowns. Current Neuropharmacology, 20, 476 – 493.

Thomson, J., Deakin, A., Cossins, A., Spencer, J., Young, I., & Sneddon,
L. (2020). Acute and chronic stress prevents responses to pain in
zebrafish: evidence for stress-induced analgesia. *The Journal of
Experimental Biology*, 223.

Sabrautzki, S., Miller, M., Kague, E., & Brielmeier, M. (2021). Welfare
Assessment of Adult Laboratory Zebrafish: A Practical Guide..
Zebrafish.

Deakin, A., Buckley, J., AlZu\’bi, H., Cossins, A., Spencer, J.,
Al-Nuaimy, W., Young, I., Thomson, J., & Sneddon, L. (2019). Automated
monitoring of behaviour in zebrafish after invasive procedures.
Scientific Reports, 9.

Ohnesorge, N., Heinl, C., & Lewejohann, L. (2021). Current Methods to
Investigate Nociception and Pain in Zebrafish. *Frontiers in
Neuroscience*, 15.

Malafoglia, V., Colasanti, M., Raffaeli, W., Balciunas, D., Giordano,
A., & Bellipanni, G. (2014). Extreme Thermal Noxious Stimuli Induce Pain
Responses in Zebrafish Larvae. Journal of Cellular Physiology, 229.

Message, R., & Greenhough, B. (2019). “But It’s Just a Fish”:
Understanding the Challenges of Applying the 3Rs in Laboratory Aquariums
in the UK. Animals : an Open Access Journal from MDPI, 9.