Mechanical hyperalgesia was measured using von Frey hairs as previously described [44 (link)]. Briefly, mice were placed in a plastic cage (10×10×13 cm3) with a mesh floor for 30 min prior to testing. Animals were placed on a wire grid floor, through which the von Frey hairs (North Coast Medical Inc. CA, USA) were applied (bending force range from 0.02 to 1.4g, starting with 0.16g) by an investigator blinded to treatment. The hair force was increased or decreased according to the response. The 50% paw withdrawal threshold was calculated using the up-and-down method [13 (link)]. Clear paw withdrawal, shaking, or licking was considered as nociceptive-like responses. Ambulation was considered an ambiguous response, and in such cases, the stimulus was repeated.