Effect of different durations of low-concentration isoflurane anesthesia on expression of NR2B in hippocampus of mice

Objective To investigate the effect of different durations of low-concentration isoflurane anesthesia on the expression of 2B subunits-containing N-methyl-D-aspartate receptors(NR2B)in the hippocampus of mice. Methods Forty C57BL/6 mice, aged 10 weeks, weighing 20-24 g, were randomly divided into 5 groups(n=8 each)using a random number table: control group(group C); 0.7%-1.0% isoflurane inhaled for 30 min group(group I1); 0.7%-1.0% isoflurane inhaled for 2 h group(group I2); 0.7%-1.0% isoflurane inhaled for 4 h group(group I3); 0.7%-1.0% isoflurane inhaled for 6 h group(group I4). Morris water maze test was carried out at 48 h after the end of anesthesia, and the escape latency and frequency of crossing the original platform were recorded.The mice were sacrificed after the end of the test, and the hippocampi were removed for determination of the expression of activated caspase-3 and NR2B(using Western blot analysis). Results Compared with group C, the escape latency was significantly shortened, and the frequency of crossing the original platform was increased in I1 and I2groups, no significant changes were found in the activated caspase-3 expression, and the expression of NR2B was up-regulated in I1, I2 and I3 groups, and the escape latency was prolonged, the frequency of crossing the original platform was decreased, the activated caspase-3 expression was up-regulated, and the expression of NR2B was down-regulated in group I4. Conclusion The mechanism underlying the effect produced by different durations of low-concentration isoflurane anesthesia on the cognitive function is related to the expression of NR2B in the hippocampus of mice. Key words: Isoflurane; Cognition disorders; Receptors, N-methyl-D-aspartate; Hippocampus