The overall aim of the following protocol is to measure anxiety like behavior in rodents. This is achieved by using a specially designed piece of equipment called the successive All's apparatus. The successive alleys apparatus consists of a series of progressively narrowing alleys, which also decrease in the height of their walls.
The anxiogenic nature of the alleys increases as the animal moves towards the narrow open end results are obtained that demonstrate changes in anxiety like behavior after genetic or pharmacological intervention. The main advantage of the successes Ali's technique, unlike existing methods like the elevated plus maze, is that there is no central area where the nature of the exploratory behavior is rather ambiguous. The successive alley's apparatus consists of four linearly connected alleys made of wood.
The alleys are designed to increase in their anxiogenic nature as they move further from the starting point. Each alley is 25 centimeters long. The width of each alley gradually decreases.
Similarly, the height of the walls decreases with each successive alley. A clamp secures the apparatus to a lab bench raising it approximately 50 centimeters above the floor. The open end of Alley one should be at least 10 centimeters away from the support to prevent mice from climbing onto it.
Place padding under the apparatus to cushion an animal if it falls. To begin, bring the mice to the experimental room for five to 20 minutes before testing for acclimation. A good practice when monitoring behavior on a novel apparatus is to first expose it to mouse soda from a non-experimental animal.
After removing the animal, clean the apparatus as you would normally before testing ready the timers that you will need for the experiment. A combined event, counter and timer as seen here works well. When ready.
Place a mouse at the closed end of alley one facing the wall. Immediately start a timer that will determine the overall length of the test and another that records the time spent in alley one. Observe the animal's exploratory behavior and record the entries latency to enter and the total time spent in successive alleys to be counted.
As an entry, the mouse must place all four feet onto the next alley. Injuries accounted, moving both forward and backward. Record the number of fecal boli and whether any urination has occurred.
If the mouse falls off, stop the clock and replace it on the alley from which it fell facing alley one. After a test time of five minutes, remove the animal and clean the apparatus with a damp cloth followed by a dry tissue. For each animal, record the latency to enter each alley, the number of entries into each and the total time spent there.
In this example, mice with lesions of the medial prefrontal cortex were tested on the traditional elevated plus maze. Lesioned animals designated by M spent more time in the open arms compared to controls shown here as group C, implying a decrease in anxiety when compared to controls. Similarly, in the success of all's apparatus, test lesioned animals spent more time in the furthest and most anxiogenic alleys of the apparatus when compared to controls.
Following this procedure. Other methods like the elevated plus maze can be used to further characterize changes in anxiety.
