The aim of this procedure is to measure strength in mice using two different tests. In the first test, the mouse is placed on a wire mesh green, which is then inverted, and the time to fall is recorded. In the second test, the mouse grips a wire mesh ball that is attached to a link of steel chain.
Additional chain links are added and the total weight that the animal can hold is recorded. Ultimately, results can be obtained that uncover differences in strength between mice. This method can be useful when studying human motor disorders.
Since full assessment of motor deficits must include specific tests of strength. To begin, bring the experimental animals into the room five to 20 minutes before testing to habituate. The inverted screen is a 43 centimeter square of wire mesh consisting of 12 millimeter squares of one millimeter diameter wire.
It is surrounded by a four centimeter wide wooden trim, which prevents mice from climbing onto the other side. To prevent the mouse from getting hurt, place something soft underneath the screen. Once habituated, place the mouse in the center of the wire mesh screen.
Start a stop clock and rotate the screen to an inverted position over the course of two seconds. With the mouse's head declining, first, hold the screen steadily 40 to 50 centimeters above a padded surface. Note the time when the mouse falls off or remove it.
When the criterion time of 60 seconds is reached. To score performance on the inverted screen, a numerical value is assigned to the time it takes for the animal to fall. For example, a fall between one to 10 seconds receives a score of one while a fall between 26 and 60 seconds.
Receives a score of three, return the animal to the home cage. After testing Several years ago, one of my students commented that a mouse was looking rather scruffy, so I thought I better give it a brush up and couldn't find a brush. But I did find a ball of stainless steel wire, which is used to descale domestic kettles.
And as I brushed her with this ball of wire, she grabbed it and held onto it furiously, and I thought, ah, there must be a test of strength here. Before using the weights test to measure strength in mice, be sure the experimental animals have acclimated to the test environment to construct a weight. Start with a ball of fine gauge stainless steel wire weighing around seven grams de, or fur collectors for domestic kettles are ideal.
The ball of fine wire is then collected to a series of steel chain links each weighing approximately 13 grams. In this example, up to seven links are attached for total weights equaling 20 33, 46, 59, 72, 85, and 98 grams. Begin the test by placing the first weight onto the laboratory bench.
Next, hold a mouse by the base of the tail and lower it until it grasps. The wire mesh. Once the mouse has a hold of the wire with its for pores, start a stop clock and raise the mouse until the link is clear of the bench.
The mouse must hold the weight for three seconds. If successful, return the animal to its home cage and tested on the next heaviest weight. After all, the other animals have been tested.
On the first For the weights test. The four pores only should be used to grasp the wire ball. If the hind legs grasp it as well simply terminate the test by putting the mouse and the weight down and trying again a few seconds later.
If the mouse fails to grip adequately, it could be a loss of motivation, and you can increase the motivation by increasing arousal levels by simply holding the mouse by the tail a little bit longer before you introduce him to the weight. If the mouse drops the weight before three seconds, record the time the weight dropped. Rest the mouse for about 10 seconds and repeat the test with the same weight.
The test is over. When the animal fails to hold the weight a third time, return the animal to the home cage and record the heaviest weight the animal was able to hold for three seconds. A total score is calculated as the product of the number of links in the heaviest chain held for the full three seconds multiplied by the time it was held.
For example, a mouse holding a five link weight for three seconds, but unable to lift a six link weight is assigned a score of five times three equaling 15. If the heaviest weight is dropped before three seconds, an appropriate intermediate value can be calculated. If a six link weight is held for only one second, a score of five times three plus one equaling 16 may be assigned.
Most people think of mice as puny little creatures, but in fact, their power to weight ratio given their small size is extremely high, and their Latin name mu musculus is entirely appropriate. Mice instinctively hold onto materials with a really strong grip. So mu musculars is an ideal model animal in which to assess disorders of muscular strength and can be used to test for possible treatments for disorders of muscular strength.
