纳洛酮对SD大鼠循环骤停后脑功能的保护作用

Protective effect of naloxone on rat brain after cardiac arrest

目的:观察纳洛酮对缺血缺氧后脑神经元内钙结合蛋白D28k表达的影响、脑组织超微结构的改变以及对神经功能的影响,探讨纳洛酮的脑功能保护作用机制。方法:实验选用29只SD大鼠,随机将大鼠分为4组:纳洛酮预处理组(8只),纳洛酮后处理组(8只),复苏对照组(8只),假手术组(5只)。采用窒息+艾司洛尔(超短效β受体阻滞剂)的大鼠心肺骤停模型。纳洛酮预处理组:纳洛酮0.3mg在心肺骤停前30min由静脉导管注入大鼠体内;纳洛酮后处理组:复苏开始后30min纳洛酮0.3mg由静脉注入。心跳骤停5min后开始进行心肺复苏,7d后大鼠处死、取脑、切片,免疫组化分析钙结合蛋白D28k的活性表达情况,透射电镜下观察脑组织损伤情况,每天对大鼠进行神经功能评分。结果:心肺复苏7d后,纳洛酮预处理组、纳洛酮后处理组、复苏对照组、假手术组大鼠海马区神经元钙结合蛋白D28k的阳性百分率分别为(41.15±6.52)%,(38.44±5.42)%,(21.69±4.17)%,(45.71±5.78)%,纳洛酮预处理和后处理组钙结合蛋白D28k的表达明显强于复苏对照组(P<0.01)。假手术组、预处理组、后处理组、对照组电镜下观察组织损伤评分为0,(4.47±3.25)%,(5.24±3.88)%,(15.06±4.39)%,纳洛酮预处理及后处理组神经组织损伤程度也轻于复苏对照组(P<0.05)。

AIM: To observe the effect of naloxone on the expression of calbindin D28k in neuron, changes of ultrastructure of brain tissue and neurological function of rats after ischemia and hypoxia, and investigate the protective mechanism of naloxone on brain function of rats. METHODS: Twenty nine Sprague Dawley rats were randomly divided into four groups:pre treatment of naloxone group (n=8), post treatment of naloxone group(n=8), resuscitation control group (n=8) and sham operated group(n=5).Rat models of cardiac arrest were established by using apnea+esmolol (ultra short acting beta receptor blocker).Rats in the pre treatment of naloxone group were injected with naloxone(0.3 mg) through venous duct 30 minutes before cardiac arrest,rats in the post treatment of naloxone group were treated with venous injection of naloxone (0.3 mg) 30 minutes after resuscitation.Cardiopulmonary resuscitation was performed at 5 minutes after cardiac arrest, and the rats were killed after 7 days, the brain was taken and sliced, and then the expression of calbindin D28k activity was analyzed by immunohistochemistry,and histologic damage of brain was observed under transmission electron microscope.Neurologic deficit score(NDS) of rats was evaluated every day. RESULTS: Seven days after cardiopulmonary resuscitation, the positive percentage of calbindin D28k in the pre treatment and post treatment of naloxone groups, resuscitation control group and sham operated group were (41.15 ±6.52)%, (38.44±5.42)%, (21.69±4.17)%and (45.71±5.78)%respectively,and the expressions of calbindin D28k in the pre treatment and post treatment of naloxone groups were obviously higher than that in the resuscitation control group(P< 0.01).The NDS scores observed under electron microscope in the sham operated group,pre treatment and post treatment of naloxone groups and control group were 0,(4.47±3.25)%,(5.24±3.88)%and (15.06±4.39)%respectively, and the damage degree in the pre treatment and post treatment of naloxone groups was milder than that in the resuscitation control group (P< 0.05), and NDS was higher than that in the control group (P< 0.01). CONCLUSION: Naloxone may promote the expression of calbindin D28k in neuron or inhibit its loss, which leads to the inhibition of calcium overload and the relief of tissue damage, and it has certain protective role in ameliorating brain faction and brain resuscitation.