Fig. 9

Orexin-A increased the PPR of paired IPSCs in the presence of naloxone in LC neurons of morphine-treated rats. a Paired IPSCs were evoked by 70 ms-separated paired pulses every 20 s. b Averaged PPR, the ratio of the averaged amplitude of 2nd IPSCs to that of 1st IPSCs in the presence of orexin-A (100 nM) and naloxone (1 μM) (data are shown as mean ± SEM, one-way ANOVA, **P < 0.01 versus baseline, n = 8)