*2.1. Mice*

C57BL/6J, 8–12 weeks old male mice from Charles River were used. Animal studies were conducted in compliance with ethical standards and with the approval of the Government of Upper Bavaria, Germany. Mice were anesthetized with the standard solution of fentanyl (0.05 mg/kg), midazolam (5 mg/kg) and medetomidine (0.5 mg/kg) applied subcutaneously (s.c.). To antagonize the narcosis, a combination of naloxone (1.2 mg/kg), flumazenile (0.5 mg/kg) and atipamezole (2.5 mg/kg) was applied s.c. To prevent postsurgical pain, mice were treated with buprenorphine (0.05 mg/kg) every 12 h until day 3.
