短期禁食诱导自噬对大鼠脑缺血损伤的保护作用

目的探讨短期禁食对大鼠脑局灶性缺血再灌注损伤的保护作用及机制。方法 57只成年雄性SD大鼠随机分为五组。假手术组(S组)、缺血再灌注组(I/R组)、短期禁食组(Fasting组)、自噬抑制剂3-甲基腺嘌呤组(3-MA组)和溶剂对照组(vehicle组)。I/R组采用右侧大脑中动脉阻闭120 min后再灌注72 h。Fasting组大鼠禁食但不禁水48 h后给予脑缺血再灌注损伤。3-MA组将3-MA 30μg溶于生理盐水10μl,于短期禁食前30 min行侧脑室注射给药,24 h后第二次侧脑室注射给药,共两次。脑缺血损伤检测指标为神经行为学评分和脑梗死容积。自噬的检测采用Westernblot测定微管相关蛋白1轻链3-II(LC3-II)的表达。结果再灌注后72 h,与I/R组比较,Fasting组可改善神经行为学评分,缩小脑梗死容积。Fasting组LC3-II的蛋白表达显著高于I/R组和S组。与Fasting组比较,3-MA组神经行为学评分降低,脑梗死容积扩大,脑损伤程度3-MA组与I/R组差异无统计学意义,表明抑制短期禁食所诱导的自噬,短期禁食的脑保护作用消失。结论短期禁食通过诱导自噬的形成减轻其后发生的大鼠局灶性脑缺血再灌注损伤。

Short-term fasting induced tolerance against focal cerebral ischemia by autophagy activation in rats

Objective To investigate whether short-term fasting have the neuroproteetive effect on focal cerebral ischemia-reperfusion injury through activation of autophagy. Methods Fifty-seven male Sprague-Dawley rats weighing 280 - 320 g were randomly divided into five groups： Sham, ischemia-reperfusion （I/R）, fasting, autophagy inhibitor 3-methyladenine （3-MA） and vehicle groups. Focal cerebral ischemia was performed using the method of right middle cerebral artery occlusion for 120 rain. Rats were deprived of food 48 h before I/R injury in fastirLg group. 3-MA （30 tag, in 10 μl normal saline ） or vehicle （10 μl, normal saline ） was administered using an intracerebroventricular injection 30 min before fasting once a day for 2 d. The neurobehavioral score and infarct volume were used to evaluate cerebral ischemic injury. Activation of au.tophagy was assessed by the level of miemtubule-associated protein 1 light chain 3-Ⅱ （LC3-Ⅱ） protein with immunoblotting. Results Short-term fasting markedly improved the neurobehavioral score and reduced the infarct volume compared with that of I/R group. The expression of LC3-Ⅱ protein was significantly increased 72 h after reperfusion in fasting group compared with the sham and I/R groups. The pretreatment with 3-MA attenuated the neuropmtective effect of short-term fasting against cerebral ischemia-reperfusion, and the neurobehavioral score and infarct volume of 3-MA group were not signiticandy different from that of I/R group, suggesting that inhibition of autophngy which induced by short-term fasting can reserve neuroprotection of short-term fasting. Conclusion Short-term fasting elicits the neuroprotective effect against transient focal cerebral ischemia through up-regadation of autophagy.