Critically ill old patients sometimes require repeated surgical interventions, and thus it is important to determine the influence of repeated exposure to anesthetics on learning and memory. Sevoflurane, a widely used inhalation anesthetic, has few neurological adverse effects and offers a rapid return to consciousness. But the long-term influence of sevoflurane exposure and the effect of repeated sevoflurane exposure on cognition have rarely been reported, and available studies are contradictory.Materials and methods:
In the present study, the Morris water maze test was employed to investigate the long-term influence of single (4 h) or repeated (2 h daily for 5 consecutive days) exposure to 1.5% or 2.5% sevoflurane on the learning ability and memory of old (16–18 months old) male rats. Testing was performed from 1 day to 4 weeks after the last exposure. In the hippocampus, brain derived neurotrophic factor (BDNF), NF-κB mRNA, and apoptosis rate were also examined to determine whether cellular biochemical changes related to cognition and memory occurred after single or repeated exposure to sevoflurane.Key findings:
Repeated exposure to 2.5% sevoflurane decreased hippocampal levels of BDNF protein, enhanced hippocampal levels of NF-κB mRNA, and increased the apoptosis rate of pyramidal cells. Single exposure to 2.5% sevoflurane, and repeated exposure to either 1.5% or 2.5% sevoflurane significantly compromised learning and memory of old male rats.Significance:
Repeated exposure to sevoflurane impaired the learning and memory of old male rats, an impairment that was accompanied by cognition-related biochemical changes in the hippocampus.