Tail withdrawal. As with the hot plate, mice were allowed 30 min of habituation. Although lightly restrained in a denim pocket, the distal half of the mouse's tail was dipped into a bath of water thermostatically controlled at 47.0°C (±0.1°C) (TW47) by Boekel Scientific/Grant Optima Immersion Circulator Model GR150 (Boekel Scientific, Feasterville, PA, USA). Latency to respond to the heat stimulus by vigorous flexion of the tail was measured. Mice received three to five trials separated by 10 seconds, with maximum trial duration of 30 seconds. If no response occurred by 30 seconds, the mouse's tail was removed from the hot water. The last three trials were recorded.
