Effect of sevoflurane on cognitive function in old rats after cerebral blood flow change

Objective To investigate the effect of sevoflurane on spatitial cognitive function and the mRNA expressions of N-methyl-D-aspartate (NMDA) receptor and the subunits of NR1 and NR2B in the hippocampus of elderly rats during the cerebral blood flow changes.Methods Thirty Wistar rats were randomly divided into 4 groups:control group (Ⅰ,n=8),2% sevoflurane group (Ⅱ,n=8),3% sevoflurance group (Ⅲ,n=8) and sevoflurane-ischemia-group (Ⅳ,n=6).All rats received 0%,2%,3% sevoflurane and O2 in a flow rate of 2 L·min-1 and N2(6 L·min-1),100 min every day for 5 days,respectively.In group Ⅳ,left common cartid artery was ligated before a week of the mixed gas exposure.The cognitive function was tested 4 times a day for 5 consecutive days using Morris water maze.The animals were killed after the Morris water maze test performance.NR,NR1 and NR2B mRNA expressions in the hippocampus were determined using reverse transcriptase-polymerase chain reaction (RT-PCR).Results The mean of latency period in Ⅰ-Ⅳ groups graduatly shorterned from 88s to 36s on day 1-5,and the swimming distance shortened from 851cm to 485cm.The swimming distance was significantly shorter on the 5th day than on the 1st day in groupⅠ,Ⅱ and Ⅲ(P0.01).The latency period on the 1st day of group Ⅲ and on 1-5th day of group Ⅳ were significantly longer than in control group.The quadrant of hidden-platform of group Ⅲ and Ⅳ were obviously shorter than that of group Ⅰ.The NR mRNA expression in group Ⅲ and NR2B mRNA expression in group Ⅳ were markedly higher than group Ⅰ.Conclusion Sevoflurane inhibits cognitive function of elderly rats in dose-dependent manner.Cerebral blood flow deficits influences the effect of sevoflurane on cognitive function in old rats.Sevoflurane at high concentration may inhibit the capacity of NMDA receptor.