Chronic sleep disturbance lead to neurodegenerative disease pathogenesis. We would like to provide a simple, stable, and long-term protocol to model frequent interruptions during human sleep to address this question. These mice minimizes handling labors and the artificial buyers.
It can standardized interventions among mice within the same experimental group and between different experiments to produce repeatable behavioral and the pathological outcomes. This model can be applied to a variety of disease models such as depression and the Alzheimer's disease to study the impacts of chronic sleep disturbance in the presence of an underlying disease. Begin by randomly assigning three to five 20 to 28 gram 8 to 10-week-old adult wild-type male mice to CSF modeling and control cages to avoid social isolation stress.
House both groups of cages in the same 21 to 23 degree Celsius and 35 to 60%humidity modeling room with a 12-hour light/dark cycle to maintain an identical surrounding environment. Then provide the mice with sufficient food and water using long nozzles with ball valve tips on the water bottles to prevent water leakage upon the platform movements and fastening the water bottles on top of each cage with a spring to avoid dislocation of the bottles during rotation. For chronic sleep fragmentation modeling, program an electrically controlled orbital rotor with a 67 by 110 centimeter platform to run during the 8:00 a.m.
to 8:00 p.m. light phase and use a solid state timer to set the rotor speed to 110 revolutions per minute for a repetitive 10 seconds on, 110 seconds off cycle. Use thick springs to fasten the CSF cages on top of the rotor platform to prevent dislocation of the cages upon platform rotation and confirm that the food and water access are maintained during the orbital rotations.
After setting up the model system, observe the cages for at least one hour to ensure that the orbital rotor is operating appropriately. During the modeling period, weigh the mice weekly at 8:00 a.m. when changing the bedding and remove any aggressors from the cages as necessary.
At the end of the modeling period, continue to house and feed the mice in the modeling room. To perform a Morris Water Maze test, between 8:00 a.m. and 12:00 p.m.
every day for five days, release one mouse at a time into a circular tank filled with 20 to 23 degree Celsius water in one of four quadrants for each trial. During the trial, use a video tracking system to record the escape latency of each mouse as it attempts to swim to the platform. If the mouse is unable to locate the platform within 60 seconds, guide the animal to the platform.
Allow it to remain on the platform for 15 seconds before returning it to its cage. On the sixth day after training, remove the platform from the water tank and release the mouse from the northeast quadrant for one final 60-second swim period per animal. After CSF modeling, no differences in the weights of mice between the control and experimental groups are observed.
The CSF group displays a reduced escapability in locating the platform over a period of five training days in the Morris Water Maze behavioral trial compared to the control animals. In the probe test, the CSF mice spent significantly less time proportionally in the targeted quadrant, crossing the previous platform location fewer times without an observable swimming speed difference. In the familiar phase of the novel object recognition test, there is no significant difference in the total exploration time between the CSF and control groups or in the exploration time between objects A1 and A2 in either group.
In the test phase, the discrimination index of the CSF mice is significantly reduced compared to that of the control animals. In these representative open field test and forced swimming test evaluations, the CSF group spent less time in the central zone during the test than did the control group. CSF mice also exhibited a longer total distance of movement within the tank, suggesting increased spontaneous activity after modeling.
Nevertheless, the CSF modeling did not induce depression-like behavior as verified by non-significant differences in the immobility time between the two groups subjected to forced swimming test. Selecting an appropriate vibrating cycle and modeling duration as well as a proper timeline for the CSF treatment and phenotype identification are important for the success of this experiment. Traditional sleep deprivation protocols require a great deal of work and the mostly for acute or short-term modeling.
This protocol allows the study of a pathological mechanism of mild but long lasting sleep disturbance.
