Figure 2. Time-course changes in root mean square (RMS) and mean power frequency (MPF) values of electromyographic signals recorded from the sacrococcygeus dorsi lateralis muscle before (C) and 20 min after pretreatment (T) with intrathecally administered aCSF or CNQX (65 or 130 nmol), followed by bilateral microinjection of 2.5 micro gram fentanyl into the locus ceruleus. Values presented are mean +/- SD, n = 6–8 animals per group. (dagger) P < 0.05 versus the corresponding baseline group in the Dunnett test. *P < 0.05 versus the aCSF group at comparable postfentanyl time points in the Scheffe test.