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

Summary

This protocol establishes a behavioral phenotyping paradigm in MPTP-treated zebrafish larvae to evaluate Parkinson's disease-like motor and non-motor deficits.

Abstract

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.

Introduction

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder after Alzheimer's disease¹. Its prevalence and the number of individuals affected have been steadily increasing in recent years, presenting a significant public health challenge worldwide². The incidence rate of PD notably escalates with age^3,4. Clinically, PD manifests through both motor symptoms -- such as dyskinesia, bradykinesia, resting tremor, and postural instability -- and a variety of non-motor symptoms, including cognitive impairment, anxiety, and sleep disturbances....

Protocol

This study involving zebrafish was conducted in compliance with institutional guidelines for animal care and use, and was approved by the Ethical Committee of the School of Pharmaceutical Sciences, Shandong University (No.YXDW2025-0056). The reagents and the equipment used are listed in the Table of Materials.

1. MPTP Preparation

1. Prepare 1× E3 medium by diluting 100× E3 stock solution 1:100 with ultrapure water (e.g., mix 5 mL of 100× E3 with 495 mL of ultrapure water to obtain 500 mL of 1× E3 medium).
   NOTE: Prepare E3 medium freshly on the day of use.
2. Prepare a 1 mM MPTP stock so....

Results

Sleep-wake regulation monitoring
The 52-h sleep-wake regulation monitoring began at 4 dpf and was conducted using a 96-well plate. Zebrafish in MPTP-treated showed significant disruptions in sleep structure compared to the WT group. Representative sleep curves, wake activity plots, and averaged activity traces are shown in Figure 2. Parameters of sleep-wake regulation analysis in zebrafish larvae are shown in Figure 3. Total sleep time was s.......

Discussion

This study developed and verified a comprehensive protocol to evaluate and analyze MPTP-induced PD-like behavioral phenotype. This protocol integrated 6 different tests, locomotor assessment, thigmotaxis assay, startle response test, photomotor response paradigms (including strobe light stimulation), light-dark challenge assay, and sleep-wake regulation monitoring, to evaluate and depict the motor and non-motor defects of PD. The results indicated that compared with the WT group, MPTP-treated zebrafish larvae showed moto.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
100× E3 stock solution	Shanghai Feixi Biotechnology	N/A	containing 34.8 g NaCl, 1.6 g KCl, 5.8 g CaCl2·2H2O, and 9.78 g MgCl2·6H2O per liter
12-Well Cell Culture Plate	NEST Biotechnology	712011	Non-Treated, Non-Pyrogenic, Sterile, Polystyrene.Used for zebrafish larval behavioral assays
24-Well Cell Culture Plate	NEST Biotechnology	702011	Non-Treated, Non-Pyrogenic, Sterile, Polystyrene.Used for zebrafish larval behavioral assays
3 mL Pasteur Pipette	Biologix	30-0238A1
6-Well Cell Culture Plate	NEST Biotechnology	703011	Non-Treated, Non-Pyrogenic, Sterile, Polystyrene.Used for zebrafish larval behavioral assays
96-Well Cell Culture Plate	NEST Biotechnology	701011	Non-Treated, Non-Pyrogenic, Sterile, Polystyrene.Used for zebrafish larval behavioral assays
MATLAB R2020a	MathWorks, USA	N/A	MATLAB R2020a, Campus-wide license obtained from Shandong University software portal (softms.sdu.edu.cn).Used for statistical analysis of zebrafish larval behavioral data.
Microsoft Excel	Microsoft	N/A	Microsoft Excel (part of Microsoft Office), version installed via Shandong University licensed software portal (softms.sdu.edu.cn).
MPTP(1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine)	Beyotime	41125281	5 mg
Petri Dish	NEST Biotechnology	704202	100 mm, sterile, easy grip handle, TC-Treated
Sodium hypochlorite solution	Macklin	S817439	stock household bleach solution(6-14% active chlorine basis), diluted to ≥10% v/v for surface and waste decontamination; also diluted 1:5 (6% bleach: water) for euthanasia of MPTP-treated zebrafish larvae.
Stereo Microscope	Olympus	SZX2 series
Zebrabox High-Resolution Video Tracking System	Viewpoint, France	N/A
Zebralab Software	Viewpoint, France	N/A	Version (3,52,3,87)