The effect of fentanyl on the lick/chew response in rabbits.

Tooth pulp stimulation in the rabbit produces a complex rhythmic lick/chew response (LCR). Because of the effect of fentanyl on the afferent and efferent components of oral function we examined its effect on this response. Intravenous fentanyl attenuates the LCR in a dose dependent manner with the ED50 occurring at 0.1 mg/kg. Concurrently a different response to tooth stimulation appears consisting of a slow, non-rhythmic lateral jaw movement (LJR). The effects of fentanyl on both LCR and LJR are blocked by naloxone (0.1 mg/kg). The dopamine antagonist, chlorpromazine (10 mg/kg iv) also has the same qualitative effect as fentanyl on both responses.