Behavioral Assessments of Spontaneous Locomotion in a Murine MPTP-induced Parkinson's Disease Model

Summary

We describe establishment of a murine model for Parkinson's disease using MPTP, and behavioral assessments using cylinder and open field tests to measure motor function. We then use L-DOPA as one example to show how to apply this model in the study of PD drugs.

Abstract

Parkinson’s disease (PD) is a common neurodegenerative disorder disease, causing the phenomenon of shaking, rigidity, slowness of movement and dementia. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) can lead to some Parkinson’s-like symptoms by destroying dopaminergic neurons in the substantia nigra of the brain. It has been thus used to establish PD models in various animal studies. Here, mice receive MPTP injections (20 mg/kg/day) for seven days and the behavioral tests are performed on the eighth day. This model is adapted efficiently in the study of PD. The behavioral tests here include the cylinder test and the open field test. The cylinder experiment is used to detect the animals’ ability to lift their front paws when put into a different environment. As the PD model mice show arching—the mouse arches its back—the number of paw liftings decrease. This test is easy to execute. The open field test is used to detect the amount of time the mice spend on running, walking, and remaining immobile. We analyze animals’ movements in open field using software and obtain data. Lastly, we use L-DOPA, one of the most commonly used PD drugs, as one example to show how to apply this model to the study of PD drugs. Our results indicate that MPTP neurotoxicity induces motor deficit which can be mitigated by L-DOPA.

Introduction

Parkinson's disease (PD), one of the most common diseases among older individuals, is a long-term neurodegenerative disorder¹_. Patients always show the phenomenon of shaking, rigidity, slowness of movement and dementia that worsen over time². Other symptoms including sensory, sleep, and emotional problems are also commonly observed². The cause of PD is still unclear, but it is generally believed to involve both genetic and environmental factors, which induce loss of dopaminergic neurons in the substantia nigra³, and development of Lewy bodies and Lewy neurite....

Protocol

This study was performed according to the international, national and institutional rules considering animal experiments. The study protocol was approved by the animal ethics committee of Nankai University.

1. MPTP and L-DOPA administration

NOTE: Ten-week-old female BALB/c mice were provided by the Institute of Zoology, Chinese Academy of Sciences. Mice were housed six per cage under a 12 h light/dark cycle (lights on at 08:00-20:00), a constant temperature of 21-22 °C and a relative humidity of 55% ± 5%. Autoclaved standard mice chow of the same formulation and water ad libitum was given to all ....

Results

In the cylinder test, the decrease of rears against the wall was observed in mice (group 2) treated with MPTP from day 1 to day 7 and saline on day 8 as compared with saline-treated mice (group 1), while an increase of rears was observed in the mice (group 3) treated with MPTP from day 1 to day 7 and L-DOPA on day 8 as compared with the mice (group 2) treated with MPTP from day 1 to day 7 and saline on day 8 (Figure 1).

Discussion

Due to destruction of dopaminergic neurons in the substantia nigra of the brain, MPTP causes Parkinson's-like symptoms in mice⁷. L-DOPA is the most preferred drug for PD ever since its clinical use, because it helps in maintaining normal daily activities in patients with PD, with effective suppression of motor abnormalities including akinesia and rigidity¹⁵. The mice treated with MPTP showed impairments in the behavioral tests like cylinder test and open field test, whi.......

Materials

Name	Company	Catalog Number	Comments
70% Ethanol	Ruiboxing Company	RBX-64175
Camera	BASLER	acA645-100gm
Cylinder test	Made in-house at Nankai University	N/A
Excel	Microsoft	N/A
Levodopa	Sigma-Aldrich	72816
Matalb 2017a	Mathworks	N/A
Mice	Institute of Zoology, Chinese Academy of Sciences	Balb/c	Adult female mice(10 weeks)
MPTP	Yuanye Biological Technology Company Ltd., Shanghai	S31504-500mg
Open field test	Made in-house at Nankai University	N/A
Syringe	Solelybio	S-xsgwz-w	Irrigation
Syringe	Jiangxi Fenglin Medical Application Co.	hc3824	Intraperitoneal injection