Phenotypic Profiling of MPTP-Induced Parkinsonian-like Behavioral Phenotypes in Zebrafish Larvae Based on Behavioral Experiment.

This article introduces a unique, multiparametric behavioral phenotyping protocol for MPTP-induced Parkinson's disease (PD) in larval zebrafish. Chemical induction of PD-like pathology in zebrafish provides a high-throughput, genetically tractable system, yet most studies have focused narrowly on basic locomotor assays or simple light-dark transitions. Such limited approaches fail to capture the broader spectrum of PD-related dysfunctions, ranging from bradykinesia and sensorimotor deficits to anxiety-like behaviors and sleep disturbances. To address this gap, this study developed an integrated battery of 6 complementary assays: locomotor test to assess general locomotor and exploratory drive; thigmotaxis assessment to detect anxiety-related edge-preference behaviors; startle response test to record bradykinesia and impaired motor reactivity; light-dark challenge assays to evaluate risk-taking and stress responsiveness; photomotor response paradigms (including strobe light stimulation) to quantify sensorimotor and reflexive movement; and sleep-wake regulation monitoring to measure sleep-wake behavior. Larval zebrafish are exposed to sublethal concentrations of MPTP from 1 day post-fertilization (dpf) to 5 dpf, with behavioral assessments initiated from 4 to 6 dpf. High-resolution automated tracking generates several behavioral endpoints per assay. This approach uncovers previously undetected PD-like alterations, such as disorderly sleep architecture, impaired habituation learning, sensorimotor and reflexive movement, reflecting early nonmotor symptoms. By combining these assays, researchers obtain a comprehensive behavioral symptom that more closely mirrors the complexity of human PD. This protocol expands the paradigm for studying PD pathogenesis, screening candidate therapeutics, and exploring environmental modulators. It exemplifies the collection's goal of presenting innovative animal models that enhance translational relevance through robust, multifaceted phenotyping.