胰岛素对吸入七氟醚小鼠海马神经元凋亡的影响

Effect of insulin on apoptosis in hippocampal neurons of sevoflurane-anesthetized mice

目的评价胰岛素对吸入七氟醚小鼠海马神经元凋亡的影响。方法清洁级健康雄性BALB/c小鼠45只，5～6周龄，体重18～22 g。按随机数字表法分为3组（n＝15）：对照组（C组）、七氟醚组（Sev组）和胰岛素＋七氟醚组（IS组）。IS组经鼻腔滴入胰岛素2 U/20 μl，连续7 d，C组给予0.9%生理盐水20 μl 。胰岛素处理结束后Sev组和IS组吸入2.5%七氟醚1 h，1 d后采用Morris水迷宫实验测试认知功能，随后处死小鼠取海马组织，采用TUNEL法计数凋亡神经元，计算凋亡指数（AI），采用Western blot法检测Bcl-2和Bax表达。结果与C组比较，Sev组术后4 d时逃避潜伏期延长，5 d时目标象限滞留时间百分比降低，AI升高，Bax表达上调，Bcl-2表达下调（P〈0.05）；与Sev组比较，IS组术后4 d时逃避潜伏期缩短，5 d时目标象限滞留时间百分比升高，AI降低，Bax表达下调，Bcl-2表达上调（P〈0.05）。结论胰岛素通过抑制海马神经元凋亡改善吸入七氟醚小鼠认知功能。

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 μl 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）.Conclusion Insulin improves the cognitive function of sevoflurane-anesthetized mice through inhibiting apoptosis in hippocampal neurons.