ABSTRACT
Objective To evaluate the effect of insulin on apoptosis in hippocampal neurons of sevoflurane-anesthetized mice.Methods Forty-five pathogen-free healthy male BALB/c mice,aged 5-6 weeks,weighing 18-22 g,were divided into 3 groups (n=15 each) using a random number table:control group (group C),sevoflurane group (group Sev) and insulin plus sevoflurane group (group IS).Insulin 2 U/20 μ1 was instilled via the nasal cavity for 7 consecutive days in group IS,and 0.9％ normal saline 20 μl was given instead in group C.After the end of insulin treatment,2.5％ sevoflurane was inhaled for 1 h in Sev and IS groups,and Morris water maze test was performed to assess the cognitive function 1 day later.The mice were then sacrificed and hippocampal tissues were obtained for determination of neuronal apoptosis (by TUNEL) and expression of Bcl-2 and Bax (by Western blot).Apoptosis index (AI)was calculated.Results Compared with group C,the escape latency was significantly prolonged at day 4 after operation,the percentage of time spent on the target quadrant was decreased at day 5 after operation,AI was increased,the expression of Bax was up-regulated,and the expression of Bcl-2 was down-regulated in group Sev (P＜0.05).Compared with group Sev,the escape latency was significantly shortened at day 4 after operation,the percentage of time spent on the target quadrant was increased at day 5 after operation,AI was decreased,the expression of Bax was down-regulated,and the expression of Bcl-2 was up-regulated in group IS (P＜ 0.05).Cornclusion Insulin improves the cognitive function of sevoflurane-anesthetized mice through inhibiting apoptosis in hippocampal neurons.