Fig. 4

Orexin-A decreased IPSCs in LC neurons of morphine-treated rats in the presence of naloxone. a Sample traces of eIPSCs at a holding potential of − 70 mV in bath application of orexin-A (OXA) and orexin-A plus naloxone (NLX). b Orexin-A pretreatment (100 nM) had no effect on the eIPSC amplitude alone compared to baseline, while orexin-A reduced eIPSC amplitude in the presence of naloxone (1 µM) (repeated measures ANOVA followed by Student–Newman–Keuls test, *P < 0.001, ***P < 0.001, n = 8). c Sample traces of sIPSCs during baseline and bath application of orexin-A and orexin-A plus naloxone. d Left, orexin-A significantly reduced the frequency of sIPSCs in the presence but not in the absence of naloxone (repeated measure ANOVA followed by Student–Newman–Keuls test, *P < 0.05, ***P < 0.001, n = 8). Orexin-A alone had no significant effect on sIPSCs frequency compared to baseline. Right, cumulative probability plots of sIPSCs inter-event interval during baseline and bath application of orexin-A and orexin-A plus naloxone. e Left, orexin-A had no significant effect on sIPSCs amplitude either alone or with naloxone compared to baseline. Right, cumulative probability plots of sIPSCs amplitude during baseline and bath application of orexin-A and orexin-A plus naloxone