Brown Institute for Brain Science

Exercised-induced Fatigue

Rationale of Test

Multiple models of muscular and neuormuscular degeneration exist. A common phenotype of these mice is a decrease in endurance or inflammation and decreased muscle function following challenge. This task was designed to assess basal locomotor activity prior to and immediately following a significant physical challenge (forced run).

Apparatus

Standard shoebox size homecage, forced run treadmill, video camera.

Procedure

Mice are placed in a standard shoebox cage for a period of 10 minutes and their behavior is recorded. Immediately following this, mice are place on a treadmill that is accelerated to 20m/Min or a period of 30 minutes. Immediately following the forced run, mice are place back into a shoebox cage for a period of 10 minutes and their behavior is again recorded. Videos are then digitally tracked to assess total locomotor activity (distance traveled, rearing, climbing, hanging, grooming) in both the pretest and post-test.

Interpretation

Typical wildtype mice will show no adverse effects of exercise challenge and will show equivocal locomotor activity in post-test compared with pre-test. However, mice with muscular or neuromuscular pathology will often show a significant decrease in locomotor activity during the post-test compared with the pretest. This test can be used to assess the efficacy of drugs to stem muscular atrophy, and fatigue in response to physical exertion.

Relevant Controls

In wildtype mice, we see no differences in pre-test/post-test locomotor activity in the following control conditions: a 30 minute interval with no running, a 30 minute interval with multiple shocks administered, or a 30 minute forced run at 20m/Min.

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