The evolutionarily conserved role of melatonin in CNS disorders and behavioral regulation: Translational lessons from zebrafish.

Melatonin is an important hormone regulating circadian rhythm, neuroprotection and neuroimmune processes. However, its exact physiological roles in brain mechanisms remain poorly understood. Here, we summarize the mounting evidence implicating melatonin in brain disorders and behavior, based on clinical and experimental studies in-vivo. In addition to rodent models, the zebrafish (Danio rerio) is becoming increasingly utilized in biomedical and neuroscience research. Here, we discuss melatonin neurobiology of zebrafish, and parallel these findings with clinical and rodent data. We also discuss the genomic effects of melatonin in zebrafish, and emphasize the growing utility of zebrafish models to study melatonin neurobiology and drug discovery.

Effects of lidocaine on adult zebrafish behavior and brain acetylcholinesterase following peripheral and systemic administration.

Lidocaine is a voltage-gated Na+ channel blocker, commonly used as a fast-acting local and general anesthetic. Lidocaine also has central action, affecting behavior both clinically and in animal models. Adult zebrafish are rapidly becoming a critical novel model organism in translational neuroscience research. Here, we examine the effects of acute peripheral (lateral line application, 4%) and systemic (water immersion, 1, 5 and 10 mg/L) administration of lidocaine on adult zebrafish behavior tested in the novel tank test. Overall, the drug evoked hypolocomotor effect when applied systemically (at 10 mg/L) and peripherally. Peripheral lidocaine also reduced top exploration in the novel tank test (vs. sham), suggesting anxiogenic-like effect of the lateral line blockage, Our findings show the importance of the lateral line system in driving adult zebrafish locomotion, and suggest sedative-like effects of systemic lidocaine in aduld zebrafish. In addition, reflecting the role of central cholinergic contribution in lidocaine action, brain acetylcholinesterase (AChE) activity was lower following peripheral and systemic administration of lidocaine at behaviorally active doses. Collectively, our data support the effects of lidocaine on behavioral responses in zebrafish, and reinforce the growing utility of this aquatic model to screen various CNS drugs.