5. Conclusion
The presented screening technique provides researchers with a valuable investigative tool for studying the biological pathways in sensory-motor systems. This can be particularly useful in future work regarding systems that may be involved in zebrafish response to electricity along with examining larvae’s locomotor response, on-demand genetic testing and in both toxicology and drug screening applications. Employing a microscope with a larger FOV, along with further modifications to the device, could increase the number of fish tested at the same time to improve the throughput of behavioral assays with the presented technology.
The functional assay presented in this research enabled us to distinguish the actions of receptor antagonists from those of agonists. We assessed alteration in electric-induced locomotor activity of zebrafish larvae following acute exposure to a variety of selective or non-selective DA antagonists and agonists. Behavioral profiles varied according to each DA receptor drug in terms of RD and TBF. Exposure to quinpirole was found to significantly increase the RD and TBF of the larval response to electric stimulus, suggesting the involvement of D2-like DA receptors in modulating zebrafish larvae electric induced response. In contrast, no significant difference resulted due to exposure to apomorphine and SKF-81297. Treatment to any of the three DA antagonists decreased RD and TBF, however, only apomorphine and quinpirole restored the response, reversing the impact of the antagonists. These results may support the claim that there are similar actions in mammals and zebrafish triggered by DA receptor drugs. Additional studies are required to pharmacologically clarify DAergic receptors’ role and involvement in the zebrafish nervous system. Although present reports typically match mammalian reports of impacted movement as a result of induced changes to the DAergic system, further work is needed to eliminate the possibility of effects on other signaling pathways. The drugs tested have higher affinities for DAergic targets. However, they cannot be solely DAergic receptor ligands. Previous research has shown that these chemicals can also bind to adrenergic, cholinergic, histaminergic, and serotonergic receptors but with lower affinity[57–59]. Additional research is needed to determine the relative affinities for these receptors to fill this knowledge gap. Internal concentrations would also need to be determined to eliminate all ambiguity regarding the amount of a drug successfully passing biological membranes such as the skin or the blood-brain barrier to be able to interact with the receptors in the brain. The proposed studies will advance the understanding of electric-induced behaviors in a lower vertebrate model recognized for high-throughput and high-content analysis.