Rationale:

The hot plate and assay models acute thermal pain. Pain sensitivity is measured on a hot plate. Latency to the first pain response is recorded as a measure of thermal pain sensitivity.

Methods:

The mice were acclimated to the testing room for at least 30 minutes. Group housed mice aged 10 weeks were used for this experiment. They were maintained on a light:dark cycle (6 am: 8 pm) with food and water available ad libitum. The hot plate (Columbus Instruments) was placed under a laminar flow hood for testing and set to 52°C. The hot plate was surrounded by a Plexiglass barrier to prevent the mice from escaping. Each mouse was placed on the hot plate and a timer was started simultaneously. The latency (sec) to the first pain response (hind-paw shake, lick, or escape jump) was recorded. The mouse was immediately removed from the hot plate. If the mouse did not emit a response within 60 seconds, it was removed from the hot plate. The hot plate was cleaned between each individual mouse that was tested.