Objective To evaluate the effect of sevoflurane on the expression of α7 nicotinic acetylcholine receptor (α7nAChR) in hippocampal neurons of rats.Methods Forty-eight pathogen-free healthy adult Sprague-Dawley rats of both sexes,weighing 210-280 g,aged 3-4 months,were divided into 4 groups (n=12 each) using a random number table:control group (group C) and 1%,3% and 5% sevoflurane groups (S1,S2 and S3 groups).In S1,S2 and S3 groups,1%,3% and 5% sevoflurane were inhaled for 1 h,respectively.Morris water maze test was performed at 1 and 7 days after anesthesia to assess the cognitive function.Six rats in each group were sacrificed after the end of the test.The brains were then removed and the hippocampi were isolated for detection of the expression of α7nAChR (by Western blot) and contents of tumor necrosis factor-alpha and interleukin-1 (by enzyme-linked immunosorbent assay).Results Compared with group C,the number of crossing the platform was significantly decreased at 1 and 7 days after anesthesia in group S1,the time of staying at the target quadrant was significantly shortened,the number of crossing the platform was decreased,and the rate of time of staying at the original platform quadrant and rate of swimming distance at the original platform quadrant were decreased at 1 and 7 days after anesthesia in S2 and S3 groups,and the contents of tumor necrosis factor-alpha and interleukin-1 were significantly increased,and the expression of α7nAChR was down-regulated at 1 and 7 days after anesthesia in S1,S2 and S3 groups (P<0.05).Compared with group S1,the expression of α7nAChR was significantly down-regulated at 1 and 7 days after anesthesia in S2 and S3 groups (P<0.05).Compared with group S2,the expression of α7nAChR was significantly down-regulated at 1 day after anesthesia in group S3 (P<0.05).There was no significant difference in each parameter of Morris water maze test among group S1,group S2 and group S3 (P>0.05).Conclusion The mechanism by which sevoflurane induces inflammatory responses in hippocampi is related to down-regulation of α7nAChR expression in hippocampal neurons of rats.