Table 1.
Awake | Medetomidine | Recovery | ||
0.055 mg/kg | 0.33 mg/kg | |||
Spontaneous movements | +++ | + | − | + |
Startle reaction to noise | +++ | + | − | +++ |
Breathing rate | +++ | ++ | + | +++ |
Motion, startling reactions, and breathing rate of mice were manually scored by an independent observer. Minus sign indicates absence. Subcutaneous medetomidine bolus induced a dose-dependent gradual decrease of motion and breathing rate. Low-dose medetomidine induced a slight decrease of locomotion but mice were still reacting to sudden noise. At the highest dose, mice stopped moving in the cage and acoustic startle reflex was absent. In recovery, medetomidine sedation was reversed by 1 mg/kg atipamezole, which essentially restored awake behavior.