Effect of sevoflurane anesthesia on expression of hippocampal α4nAchR in rats

Objective To evaluate the effect of sevoflurane anesthesia on the expression of hippocampal α4 subunit-containing nicotinic acetylcholine receptor (α4nAChR) in rats. Methods One hundred and forty-four Sprague-Dawley rats of both sexes, aged 3-4 months, weighing 220-270 g, were divided into 4 groups (n=36 each) using a random number table: control group (group C), sevoflurane anesthesia for 1 h group (group S1), sevoflurane anesthesia for 3 h group (group S2) and sevoflurane anesthesia for 5 h group (group S3). Group C inhaled air, and S1, S2 and S3 groups inhaled 3% sevoflurane for 1, 3 and 5 h, respectively.Twelve rats in each group were selected at 1 and 7 days after emergence from anesthesia to undergo spatial probe test.Rats were then sacrificed immediately after anesthesia and at 1 and 7 days after emergence from anesthesia, and hippocampi were removed for determination of the expression of α4nAchR protein and mRNA in hippocampal neurons (by Western blot or real-time polymerase chain reaction). Results Compared with group C, the duration of staying at the target quadrant was significantly shortened, and the ratio of duration of staying at the original platform quadrant to the total duration and ratio of swimming distance in the original platform quadrant to the total distance were decreased on 1 and 7 days after emergence from anesthesia, the expression of α4nAchR protein and mRNA was down-regulated, and the number of positive cells was reduced in S1, S2 and S3 groups (P 0.05). Conclusion The mechanism by which sevoflurane anesthesia induces cognitive dysfunction may be partially related to down-regulating the expression of hippocampal α4nAchR in rats. Key words: Anesthetics, inhalation; Cognitive disorders; Receptors, cholinergic; Postoperative complications