Triggering and Monitoring Heat-Induced Seizures in a Transgenic Mouse Model

Take an anesthetized transgenic adult mouse carrying a gene mutation that leads to dysfunctional sodium channels in the inhibitory interneurons.

Secure a lubricated rectal probe to monitor its body temperature.

Place the mouse in a recovery cage until its body temperature stabilizes.

Next, transfer the animal to a preheated heat chamber and begin video recording.

Increase the chamber's temperature at regular intervals while monitoring the gradual rise in the mouse's body temperature.

As the body temperature rises, the dysfunction in sodium channels worsens, reducing inhibitory neurotransmitter release.

This reduced release disrupts the balance between neuronal excitation and inhibition, resulting in neuronal hyperexcitability and seizures.

Record the body temperature during the seizure and note its behavioral characteristics.

Now, place the mouse on a cooling pad until its body temperature normalizes.

Finally, remove the rectal probe and allow the mouse to recover.

Start by switching on the mouse heat chamber, with the power on button and then press the heat on button. Using the keypad on the digital temperature controller, set the temperature of the heat chamber to 50 degrees Celsius. Line the floor of the heat chamber with cob bedding.

Mount a video recording camera in front of the heat chamber. Line a 140-millimeter-diameter Petri dish with thick layers of tissue paper and place it on ice to serve as a cooling pad. For the screening assay, ensure the body weight of the mouse is 15 grams or more. Before starting the procedure, confirm that the mouse is completely anesthetized with a toe pinch.

Coat the metal tip of the rectal temperature probe with a lubricant, and gently insert it into the mouse. Secure the rectal probe to the tail of the mouse with tape. Place the mouse in a new recovery cage lined with cob bedding. Start a timer, and observe the mouse for 5 minutes while monitoring the core body temperature until the mouse completely recovers from anesthesia, and the temperature stabilizes at 35 to 36 degrees Celsius.

At the end of 5 minutes, note the body temperature of the mouse as the initial body temperature at 0 minute. Transfer the mouse quickly to the floor of the preheated mouse heat chamber to start the experiment's trial. After the mouse is placed into the preheated mouse chamber, start the camera and the stopwatch.

Increase the temperature of the heat chamber at regular intervals, such that the body temperature of the mouse increases at a rate of 0.25 to 0.5 degrees Celsius per minute. Begin recording the body temperature of the mouse at 1-minute intervals for the duration of the experiment. At 9.5 minutes, set the temperature of the heat chamber to 55 degrees Celsius, to stabilize the temperature of the heat chamber at 55 degrees Celsius by the 10th minute.

Similarly, achieve a stable temperature of the heat chamber to 60 degrees Celsius by the 20th minute. Each seizure screening trial lasts for 30 minutes. If the mouse experiences a seizure, record the body temperature of the mouse during the seizure as a seizure threshold temperature. Take note of the seizure behavior characteristics displayed by the mouse.

Then, quickly pick up the mouse from the chamber and place it on the cooling pad. When the body temperature of the mouse comes down to 36 to 37 degrees Celsius, transfer the mouse to a recovery cage. To remove the rectal probe from the mouse, carefully cut the tape between the mouse tail and the rectal probe wire.