Figure 2.

Comparison of behavioural responses elicited by intracisternal and lumbar intrathecal morphine (100 nmol). (A) Time course of thermal nociceptive responses evaluated by measuring tail-withdrawal latency in 50°C water at baseline (BL) before and 15, 30, 45 and 60 min after administration. *P < 0.05, significantly different from the baseline for all time points for both intracisternal and lumbar intrathecal morphine. (B–F) Time course of scratching responses in each 15 min time block during a 60 min observation period. Behavioural responses were recorded 5 min after morphine administration. The number of total scratches (B), head and body scratches (C and D), were counted and the percentage of head and body scratches (E and F) were calculated. Each data point represents mean ± SEM (n = 4). *P < 0.05, significant difference between intracisternal and lumbar intrathecal morphine at the corresponding time point.