Figure 1

Measurement of voluntary movement in a carrageenan-induced inflammatory pain model. (A) Left, Carrageenan (2% in 40 μl) or saline was injected subcutaneously (s.c.) into the plantar surfaces of both hindpaws in rats. Latency of withdrawal response to a thermal stimulus was measured (n = 5–10, ***p<0.001) at 2h, 3h, 4h after carrageenan injection. Results are means ± SEMs. Middle, Number of rearings were measured at 2h, 3h, and 4h after carrageenan or saline injection for 20 min (n = 7–9). Right, Pearson correlation analysis of the relation between number of rearings and withdrawal latencies to noxious thermal stimuli in rats at 2h, 3h, and 4h after carrageenan injection (n = 5–9, *p<0.05, r² = 0.92). (B) A trace of rat movements over 20 min after administering saline (CTL) (left) or carrageenan (Carr). (C) Total distances moved over 20 min were measured at 2h, 3h, and 4h after carrageenan or saline injection (n = 7–9). The correlation between total distance moved and withdrawal latency to noxious thermal stimuli was performed in rats 2h, 3h, and 4h after carrageenan injection (n = 5–9, r² = 0.9).