间歇缺氧大鼠海马神经元凋亡及其机制

The change and mechanism of apoptosis in the hippocampal CA1 region of rats exposed to intermittent hypoxia

目的探讨间歇缺氧对大鼠海马组织氧化应激状态及海马神经元凋亡的影响及其可能的机制。方法将36只雄性 Wistar 大鼠随机分为间歇缺氧组、持续缺氧组和正常对照组,每组12只。采用化学比色法测定海马组织丙二醛和超氧化物歧化酶(SOD)水平,应用 Western 免疫印迹法检测海马 CA1区磷酸化 C-JUN 氨基末端激酶(p-JNK)、磷酸化 c-jun(p-c-jun)的表达水平,应用缺口末端标记(TUNEL)法检测海马 CA1区神经元凋亡率。结果间歇缺氧组大鼠海马 CA1区丙二醛水平为(1.61±0.39)nmol/mg 蛋白,显著高于正常对照组的[(1.25±0.29)nmol/mg 蛋白]和持续缺氧组的[(1.34±0.24)nmol/mg 蛋白];间歇缺氧组大鼠海马 CA1区 SOD 水平为(45±13)NU/mg 蛋白,显著低于正常对照组[(58±12)NU/mg 蛋白]和持续缺氧组[(56士10)NU/mg 蛋白];持续缺氧组与正常对照组的差异均无统计学意义。间歇缺氧组 p-JNK、p-c-jun 表达显著增高,分别是正常对照组的2.1倍及2.3倍;间歇缺氧组海马 CA1区神经元凋亡率为(0.30±0.16)%,显著高于正常对照组[(0.12±0.07)%]和持续缺氧组[(0.17±0.09)]。结论间歇缺氧可导致海马 CA1区氧化应激状态,从而激活 JNK 信号传导通路,介导海马神经元凋亡,这可能是阻塞性睡眠呼吸暂停低通气综合征患者神经功能障碍的病理生理基础之一。

Objective To investigate the effect of intermittent hypoxia on rat hippocampal oxidative stress and neuron apoptosis in the hippocampal CA1 region. Methods Thirty six healthy male Wistar rats were randomly divided into three groups of 12 each： a control （NC） group, an intermittent hypoxia （IH） group and a sustained hypoxia （SH） group. The levels of Malondiadehyde （MDA） and Superoxide dismutase （SOD） were detected by colorimetric method. Western blotting was used to examine the expression of p-JNK and p-c-jun. TUNEL was used to detect the neuron apoptosis in the hippocampal CA1 region. Results The level of MDA （ nmol/mg protein） in the hippoeampal CA1 region in IH group （ 1.61 ± 0. 39 ） was significantly higher than those in NC group （ 1.25 ± 0. 29 ） and in SH group （ 1.34± 0. 24）, F =4. 185, P 〈 0. 05; the level of SOD （NU/mg protein） in IH group （45 ± 13） was significantly lower than those in NC group （58 ± 12） and in SH group （56 ± 10）, F =4.338, P 〈0.05. There were no significant differences between SH and NC groups in the level of MDA or in the activity of SOD （P all 〉 0. 05 ）. The expression of p-JNK and p-c-jun in IH group were 2. 1 and 2. 3 times the expression in the NC group respectively. The apoptotic indices of IH group （0. 30 ±0. 16） was significantly elevated as compared with group NC （0. 12±0.07） andSH （0. 17±0.09）, F=7.766,P〈0.01. Conclusion Oxidative stress associated with IH in the hippocampal CA1 region can activate JNK signaling pathway, leading to the apoptosis of hippoeampal neuron. This maybe the pathophysiological basis of obstructive sleep apnea hyponea syndrome with neurobehavioral impairments.