Mechanical nociceptive threshold testing

Mechanical nociceptive threshold was quantified using an Ugo Basile Analgesymeter^® (Randall-Selitto paw-withdrawal test; Stoelting, Chicago, IL), which applies a linearly increasing mechanical force to the dorsum of the rat's hind paw, as previously described [26; 61; 62]. The nociceptive threshold was defined as the force in grams at which the animal withdrew its paw; baseline paw-pressure nociceptive mechanical threshold was defined as the mean of the 3 readings taken just before a test agent was injected. Each paw was treated as an independent measure and each experiment performed on a separate group of rats. Data are presented as mean change from baseline mechanical nociceptive threshold.