Delayed recovery of behavior after anesthesia in rats

Early, complete recovery from general anesthesia is of importance for outpatients, in resuscitation research and in behavior testing of neonates. A model was designed to study behavior during the first week of recovery from anesthesia in rats, using two methods: spontaneous and unrestrained locomotor activity was tested and passive avoidance of electroshock was studied in a two session, one trial model. Neurologic deficit and ease of handling were also tested. After anesthesia with halothane 1-2% in N2O/O2 for 30 min, spontaneous activity was reduced, compared with unanesthetized rats, for up to at least 48 h. On day 6 post-anesthesia, locomotor activity was recovered, and, on days 4 and 5, passive avoidance was unchanged. Neurologic deficits were absent after the first hour of recovery and ease of handling was unchanged.

Halothane and nitrous oxide have prolonged effects on locomotor behavior beyond the immediate post-anesthesia recovery period, at a time when neurologic deficit testing does not reveal any abnormalities. The model is suitable for the comparison of recovery from different anesthesia techniques in rats.