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

In this video, we introduce how to use a cylinder and open field test to narrow motor function in the MPTP model of Parkinson's disease. The primary advantage is that the mice don't need to be trained before the behavioral test. Additionally, this method is efficient and the cost of the equipment is low.

Individuals who are new to behavioral tests may underestimate the effect of environmental interference. Keeping quiet and avoiding changes in lining will help. Here, behavioral testing is conducted 24 hours after the final injection of a seven day regimen of MPTP or saline injections and 40 minutes after intragastric administration of L-DOPA to a subset of the animals.

If behavioral testing is not performed in the same room where the animals are housed, acclimate the mice to the new room for 30 to 60 minutes before the test. Begin by placing a transparent glass cylinder at the center of a table. Surround the cylinder on three sides with black cardboard, placed four to eight centimeters away from the cylinder to reduce the effect of environmental lighting.

Leave one side of the cylinder facing the camera for video recording. Attach a camera capable of at least one million pixel resolution 40 to 60 centimeters away from the cylinder to ensure that the whole cylinder is contained in the field of view. Place one mouse into the cylinder at a time and start filming at once.

During this process try to avoid noise or light changes in order to avoid influencing the mouse's behavior. Paw lifts occur when the mouse rears up on it's hind limbs, raises both forelimbs above shoulder level, and lands. Stop filming after three minutes and place the mouse back into the home cage.

Clean the cylinder with water and then spray 70%ethnol over the inner wall to sanitize it and remove mouse scents. Wipe the cylinder dry before testing the next mouse. Once testing is completed, play back the video at a rate of 0.5 times the regular speed and count the number of paw lifts against the wall of each mouse.

If the mouse raises its forelimbs above shoulder level several times continuously without landing, it should be counted only once. Perform open field testing during the same session as the cylinder test. Prepare a transparent open field reaction box with a wooden plate, covered by a contrasting black or white cloth depending on the color of the mouse.

Fix a camera over the field at a height of one meter. Adjust the camera to make sure that the open field reaction box is right in the center of the video. Put one test mouse into the box and let the mouse familiarize itself with the environment for about one minute.

Record a five minute video using the camera connected to the computer. Finally, clean up any feces in the open field reaction box, spray 70%ethanol on the box, and wipe it. In the cylinder test, a decrease in the number of rears against the wall was observed in mice treated with MPTP compared with saline treated mice.

Increased rears were observed in the MTPT treated mice given L-Dopamine on the day of testing compared to the MPTP treated mice receiving saline. This image show the representative movement trace and the distribution of static time, walking time, and running time in control mice not treated with MPTP. Mice treated with MTPT demonstrated lower movement speed, shorter movement distance, longer static time, and shorter running time then saline treated mice, demonstrating a motor deficit induced by MTPT.

MPTP treated mice receiving L-Dopamine showed a higher movement speed, a longer movement distance, a shorter static time, and a longer running time than the mice treated with just MPTP, indicating that L-Dopamine mitigates the MPTP-induced motor deficit. When changing the mice being tested clear the area completely and spray ethanol to eliminate the effect of the scent of the former mice. Following this procedure, other measures such as the beam walking test, pole test can be performed.

Data related to balance capacity and motor ability can be gained through these methods. MPTP is neurotoxic for both mice and humans and so strict precautions must be taken to avoid exposure. Extra PPE, such as a mask or respirator should be worn.