Number of Fos-IR cells (mean ± standard error of the mean) in the central amygdala (CEA) and lateral hypothalamus (LH) in the without orthodontic appliance (without OA) group, in the group that received the inactivated (without force) or activated (30g) or (70g) OA, and in the group that was pretreated with morphine sulphate (MS, 2 mg/kg) before the insertion of an OA activated with a 70g. *P < .05 compared with other groups by the Tukey test. Number of rats analyzed in parentheses