The overall goal of this procedure is to measure motor coordination in mice. This is accomplished by first testing on the accelerating rotor rod. Next motor coordination is tested on the onal bar.
The animal can also be tested on static rods. Lastly, performance on the parallel bars can be measured. Ultimately, results can be obtained that show whether the mouse has any impairments in motor coordination.
Generally, individuals new to this technique will struggle because of the difficulty of correctly placing the mouse on the apparatus For all of the following tests. Bring the mice to the experimental room five to 20 minutes before testing to ensure they are fully awake. The rotor rod scene here was built at the University of Oxford.
The rod is three centimeters in diameter with a series of parallel ridges on its surface, which help the mice to grip it more effectively. A flange on each side prevents the mouse from leaving the rod. They are 30 centimeters in diameter and six centimeters apart.
The rod is secured 30 centimeters from the base of the apparatus. A soft padded surface is placed at the base to cushion any falls before beginning the trial. Prepare the rotor rod by setting a start speed of four rotations per minute and an acceleration rate of 20 rotations per minute.
To begin, hold the mouse by the tail and bring it up towards the rod at a 45 degree angle below the horizontal. Quickly release the animal when it is almost touching the rod. Alternatively, the mouse can be lowered onto a dowel and the dowel will used to transfer the animal to the rod.
Start the acceleration 10 seconds after placing the mouse on the rod and note the speed at which the mouse falls off. If the mouse falls before five seconds and is likely due to poor placement by the experimenter, the result should not be recorded and the trial restarted if the mouse falls before 10 seconds. Note the time and allow the animal two more tries.
For animals that stay on past 10 seconds, record the speed at which the animal falls. Occasionally the mouse may stop walking and consequently, some assault around the rod before eventually falling. It is useful to note the speed of this occurrence.
Performance is calculated as the mean speed between trials. For example, a mouse that falls before 10 seconds once and then stays on until 12 rotations per minute. The second time scores four plus 12 divided by two equaling eight rotations per minute.
The horizontal bar measures fall limb strength and coordination while a bar two millimeters in diameter is most commonly used. Bars of larger diameter may provide more refined performance scores. Brass bars 38 centimeters long are held 49 centimeters above the bench surface by a wooden support column.
The bars are held under tension when fitted into the notches of supports that are drawn slightly together. Begin testing with the two millimeter bar. Hold the mouse by the tail and place it on the bench in front of the apparatus.
Slide it quickly. Backwards about 20 centimeters to align its body perpendicular to the bar rapidly. Raise the animal allowing it to grasp the horizontal bar at the center with only its four pores.
Release the tail while simultaneously starting a stop clock. If the mouse fails to grasp the bar and the experimenter's placement may be the cause. Do not record the fall and retest the animal after a brief rest.
If the mouse falls before five seconds, and this is apparently not due to poor placing by the experimenter, repeat up to three times in an attempt to get a score greater than five seconds. Record either the time the mouse falls or the time until one four poor touches a column with a maximum test time of 30 seconds, take the best score as the datu Right to score the horizontal bar. If the mass falls off between one and five seconds, score one between six seconds and 10 seconds.
Score two between 11 seconds and 20 seconds. Score three between 21 seconds and 30 seconds. Score four falling after 30 seconds or just staying on the bar till 30 seconds.
Scores five, and the mouse also scores five if it touches an end. Support with its four port at any time during testing. If a score of five is achieved on the two millimeter bar, the animal can then be tested on thicker bars after a brief rest.
The scoring system for the four and six millimeter bars is the same as for the two millimeter bar, and the final score is the cumulate total. Thus, a mouse that scores five on the two millimeter bar but falls from the four millimeter bar after 13 seconds. Scores five plus equals eight.
In this test for motor coordination, wooden dows or rods of varying thickness, 35 28, 22 15, and nine millimeters in diameter each 60 centimeters long affixed by a G clamp to a laboratory shelf 60 centimeters from the floor. A mark is made 10 centimeters from the end near the bench to denote the finish line. To begin place the mouse at the far end of the widest rod facing away from the shelf record the time it takes for the animal to orientate itself towards the shelf and that total transit time.
If the mouse turns upside down and clings below the rod during orientation, arbitrarily assign it to the maximum score of 120 seconds. The animal is not tested on the other rods and receives a maximum transit value as well. If the mouse falls or reaches the maximum test time of 120 seconds after orienting, do not test it on narrower rods.
A maximum score is also assigned if the mouse turns upside down while transversing the rod after orientation, return the mouse to the home cage and allow it to rest before testing. The next smaller rod. Place the animal on the smaller rod as shown earlier.
If the mouse falls off before five seconds, replace it and allow up to two more attempts. Record the time to reverse the rod or until the mouse falls off. To set up the parallel bars support two bars, one meter in length and four millimeters in diameter, 30 millimeters apart on wooden support.
Columns 60 centimeters above the floor. Place the mouse in the center of the two bars with its longitudinal axis perpendicular to the bars. Both front pores should be on one bar with both hind pores on the other bar.
Scoring is similar to that for the static rods. Two measures are taken the time until the mouse orients 90 degrees to the start position and the time until it reaches one of the end supports. Similarly, orientation and transit must be achieved without the animal turning upside down, otherwise the maximum time is allotted.
If the animal falls before five seconds, it is probably due to poor placing and the animal should be retested. A static rod was originally used to monitor the progress of disease in mutant mice with or without environmental enrichment in their home cages. The enrichment program dramatically delayed the onset of motor dysfunction on the rod, which was paralleled by a delay in the onset of hind poor clasping.
A general sign of neurological ment scrapy infected mice showed a decrease in horizontal bar performance from week 16 post-injection in rotor rod testing from week 18 and static rods from at least week 19. Hippocampal lesions had no effect on any measure of motor ability, but 1 2 9 s two SV mice were impaired relative to the C 57 black six strain on the rotor rod and static rods After its development. This technique paved the way for researchers in Huntington's disease to study the effects of environmental enrichment in Huntington's disease mutant mice.
