Figure 4.

Time course of flinching behavior (Top) and concurrent assessment of lumbar spinal glutamate (Middle), and PGs E2 (Bottom) release measured in unanesthetized rats before and after the injection of formalin (5%/50 μl) into the left hind paw of the rat at time = 0. At −10 min, the rats received an intrathecal (IT) injection of saline (vehicle: n = 4) or morphine (10 μg; n = 7). Release was assessed by using a chronically implanted loop dialysis probe (27), and the intrathecal injection was through a chronic intrathecal catheter. Each line presents the mean of four and seven rats, respectively. Error bars deleted for clarity. ∗, P < 0.05 versus formalin; #, P < 0.05 vs. IT saline.