Effect of propofol on memory in mice.

The amnestic effects of the intravenous hypnotic anesthetic agent 2,6-diisopropylphenol (propofol; Diprivan) were studied in a single-trial passive avoidance task. Mice were injected with propofol 10 min before or immediately after training. Memory was impaired in a dose-dependent fashion when the anesthetic was administered before learning, but no amnesia was apparent with posttraining injections. Examination of the acquisition of passive avoidance using a multitrial task showed that propofol-treated mice learned the response normally but forgot the learning significantly faster than vehicle-treated controls. The anterograde amnesia was not the result of state-dependent learning. Propofol also disrupted extinction of fear conditioning when the anesthetic was given during the extinction session. Propofol-induced amnesia could be attenuated by amphetamine (1 mg/kg) injected 30 min before the retention test.