Thermal Hyperalgesia Assessment in mTBI Mice

Thermal hyperalgesia was evaluated at 14 and 30 days after mTBI or sham surgery by the Plantar Test Apparatus (Ugo Basile, Varese, Italy), as described by Guida et al., 2017 (link). On the day of the experiment each mouse was placed in a plastic cage (22 cm × 17 cm × 14 cm; length × width × height) with a glass floor. After 30 min habituation period, the plantar surface of the hind paw was exposed to a beam of radiant heat through the glass floor. The radiant heat source consists of an infrared bulb (Osram halogen-bellaphot bulb; 8 V, 50 W). A photoelectric cell detected light reflected from the paw and turned off the lamp when paw movement interrupted the reflected light. Data were expressed as thermal withdrawal latency (TWL) in seconds and TWL was automatically displayed to the nearest 0.1 s; the cut-off time was 20 s in order to prevent tissue damage. Each mouse served as its own control, the responses being measured both before and after surgical procedures. An observer blind to the treatment quantified TWL.