Fig. 1.

Thermal antinociceptive effects of morphine under the UCMS condition. The effects of morphine on thermal nociceptive latency (a) and %MPE (b) in a hot-plate test under the UCMS (closed circles n = 15) and non-stress (open circles n = 13) conditions. Intraperitoneal morphine was repetitively administered to the mice at doses of 1, 2, and 7 mg/kg, for cumulative doses of 1, 3, and 10 mg/kg, respectively. ^## p < 0.01, ^# p < 0.05, significantly differed from the non-stress condition. Data are expressed as mean ± SEM.