Objective

To analyse the effect of physical activity and L-Methionine supplemented diet in 2.2% in the evolution of Alzheimer’s disease. In addition, the effect of sedentarism in the development of this disease will also be analysed.

Subjects

30 Taconic APPSWE (Alzheimer model) mice randomly distributed into 3 groups:

• Physical activity. This group has free access to the wheel, and the amount of physical activity carried out by each mouse is registered. Their diet is the usual one for mice.

• Supplemented diet. Mice of this group do not have free access to the wheel. Their diet is supplemented with L-Methionine in 2.2%.

• Sedentary. They do not have free access to the wheel and have the same diet as the mice of the physical activity group.

Through the experiment, the following tests will be executed:

• Y maze. The base is the radial maze, in which some arms are closed so as to have the shape of a Y. There is a hole at the end of both left and right hand. Food is placed in one of these arms, but not in the other. As food is inside the hole, the mouse is not able to see where the food is. The mouse is located in the beginning of the maze, and its learning abilities and memory are studied, taking into account the number of rights and the needed time to find the food. This action must be carried out five consecutive times. If the mouse goes in the negative arm, the number of attempts in which the mouse entered the positively-reinforced arm will start from zero. The mouse has one minute in each attempt. Once the minute has passed, the mouse is shut in for 30 seconds in the negatively-reinforced arm and another 30 seconds in the starting arm. Then, a new attempt is carried out. Each mouse has 10 consecutive attempts once a week. See animation.

• T maze. The base is the radial maze, in which some arms are closed so as to have the shape of a T. There is a hole at the end of both left and right hand. Food is placed in one of these arms, but not in the other. As food is inside the hole, the mouse is not able to see where the food is. The mouse is located in the beginning of the maze, and its learning abilities and memory are studied, taking into account the number of rights and the needed time to find the food. This action must be carried out five consecutive times. If the mouse goes in the negative arm, the number of attempts in which the mouse entered the positively-reinforced arm will start from zero. The mouse has one minute in each attempt. Once the minute has passed, the mouse is shut in for 30 seconds in the negatively-reinforced arm and another 30 seconds in the starting arm. Then, a new attempt is carried out. Each mouse has 10 consecutive attempts once a week. See animation. See animation.

• Radial maze. The mouse must find in which arm the food is. In this case, the food is in the first arm that is at the right from the starting line. This maze has a negatively-reinforced arm. This arm will shut the mouse in if it enters. In this case, the negative reinforce is in the first arm at the left. The mouse will be considered to have learned when it chooses the arm with the food as a first option and avoids the negative one. This action must take place five consecutive times. If the mouse goes in the negative arm, the number of attempts in which it entered the positively-reinforced arm will start from zero. The mouse has one minute in each attempt. Once the minute has passed, the mouse is shut in for 30 seconds in the negatively-reinforced arm and another 30 seconds in the starting arm. Then, a new attempt is carried out. Each mouse has 10 consecutive attempts once a week. See animation.

The following video shows a mouse from the physical activity group in the maze for the first time. As can be seen, its first option is to go to the arm of the T maze where the food was the previous time. This video shows how the mouse explores the different arms and learns in which one it should enter.

Ingurune from INGEMA on Vimeo

• Morris water maze

• Object recognition

This test is based on the natural tendency of mice of exploring new objects. First, the mouse is placed in a uniformly lit cage and without any stimulus for 10-30 minutes. 24 hours later, the mouse is placed in the cage once again, but this time two identical objects (A1 and A2) are put in two different parts of the cage. The time dedicated to explore each of the objects is registered for 10 minutes. One hour later, the same exercise is done but one of the objects is substituted for a new one (A1 and B1), and the time dedicated to explore each of the objects is registered once again. Two hours later, the same exercise is done with the same objects (A1 and B1) and the time is measured. The following day, the B1 object is substituted with a new object, C1, and the time used to explore is registered.