Our goal was to develop an effective and affordable voluntary wheel running protocol that could measure individual running parameters in mice while minimizing the effects of social isolation. The gap in current VWR protocols is the inability to accurately measure individual running metrics in mice without avoiding isolation induced stress or relying on general cage performance data. The advantage of our protocol is presenting an efficient voluntary rerunning model suitable for various research contexts that avoids isolation housing while accurately tracking individual running metrics in mice.
This protocol could allow stress paradigms to explore the impact of exercise on behavior in group housed mice, while accurately measuring individual metrics without introducing the stress associated with isolation housing. To begin, apply glue to the outer middle circumference of each wheel and affix one magnet. This magnet will be detected by the sensor of the speedometer to monitor the voluntary wheel running.
On the opposite side of the wheel, glue an object of similar weight, such as a coin, to counterbalance and prevent unwanted rotation due to the weight of the magnet. Cut out a piece of a white foam board in a complimentary shape to the base of the wheel. Tape it with waterproof adhesive paper to serve as a stage for the speedometer and wheel.
Insert a fresh set of batteries into the speedometer. Then set the wheel size during initial programming by measuring the outer circumference of the wheel. Stick the speedometer sensor to the platform.
Ensure that the sensor is placed parallel to the magnet of the wheel to allow for proper recording of movement. Wrap the sensor and wire with duct tape to prevent wire chewing by mice. Set up a behavioral apparatus with a box to test for mice simultaneously.
Then cut white foam into two board pieces that are 30 centimeters long and 40 centimeters wide. Make a 20 centimeter cut in the middle of the width of the board to allow the intersection of the two foam boards. Then cover the foam board with waterproof adhesive paper to allow for easy cleaning between groups.
Use the two intersecting foam boards to divide the apparatus box into four quadrants. Now place one prepared wheel in the corner of each quadrant. Secure the wires to the wall with tape and attach the speedometers to the side of the clear Perspex apparatus.
For no exercise control mice, lock the wheels using hot glue to immobilize the wheel's rotation center and disable rotation. For voluntary wheel running, place the mice in the voluntary wheel running room to habituate for 30 to 60 minutes, then reset all speedometers before starting the session. Place each mouse in the corner of its assigned quadrant where it can freely run.
After two hours, return the mice to their home cage and record the speedometer data. Clean the arenas and wheels with 70%ethanol between groups to prevent scent contamination. Mice demonstrated the highest voluntary wheel running activity during week two, spending an average of 2, 135.87 seconds on the wheel, traveling 1.16 kilometers and running at a speed of 2.25 kilometers per hour.
The lowest voluntary wheel running activity was recorded in week six with mice spending an average of 1, 136.48 seconds on the wheel, traveling 0.56 kilometers, and maintaining a speed of 2.21 kilometers per hour. After five weeks of voluntary wheel running, the mice exhibited a 26.87%increase in investigation time during the spatial object recognition test indicating improved hippocampal function.
