N-乙酰-L-色氨酸对大鼠肝脏缺血再灌注后肠损伤的保护作用

目的 探讨N-乙酰-L-色氨酸(L-NAT)对大鼠肝脏缺血再灌注中肠损伤的保护作用.方法 将健康成年雄性SD大鼠24只分为假手术组(Sham组)、缺血再灌注组(IR组)和缺血再灌注加L-NAT组(IR+ L-NAT组).用夹闭肝中叶和左叶肝蒂分支的方法制作肝缺血再灌注模型,用苏木素-伊红(HE)染色法观察小肠组织的形态学结构,用免疫组织化学染色观察激活型Caspase-3、Bax、Bcl-2的表达.结果 (1)IR组小肠绒毛结构破坏,肠黏膜充血脱落,上皮细胞变性坏死,出现炎症细胞浸润;L-NAT可使之减轻.(2)免疫组织化学染色显示,与Sham组相比,IR组激活型Caspase-3、Bcl-2和bax的表达升高,L-NAT干预后,Caspase-3和Bax的表达下降,而Bcl-2的表达进一步升高.结论 L-NAT可抑制肝脏缺血再灌注损伤引起的小肠上皮细胞凋亡,减轻小肠上皮细胞损伤.     

N-acetyl-L-tryptophan,a substance-P receptor antagonist attenuates aluminum-induced spatial memory deficit in rats

Neuroinflammation plays an important role in the pathophysiology of Alzheimer’s disease. Neurokinin substance P is a key mediator which modulates neuroinflammation through neurokinin receptor. Involvement of substance P in Alzheimer’s disease is still plausible and various controversies exist in this hypothesis. Preventing the deleterious effects of substance P using N-acetyl-L-tryptophan, a substance P antagonist could be a promising therapeutic strategy. This study was aimed to evaluate the effect of N-acetyl-L-tryptophan on aluminum induced spatial memory alterations in rats. Memory impairment was induced using aluminum chloride (AlCl₃) at a dose of 10?mg/kg for 42 d. After induction of dementia, rats were exposed to 30 and 50?mg/kg of N-acetyl-L-tryptophan for 28 d. Spatial memory alterations were measured using Morris water maze. Acetylcholinesterase activity and antioxidant enzyme glutathione level were assessed in hippocampus, frontal cortex and striatum. The higher dose of N-acetyl-L-tryptophan (50?mg/kg) significantly improved the aluminum induced memory alterations. N-acetyl-L-tryptophan exposure resulted in significant increase in acetylcholinesterase activity and glutathione level in hippocampus. The neuroprotective effect of N-acetyl-L-tryptophan could be due to its ability to block substance P mediated neuroinflammation, reduction in oxidative stress and anti-apoptotic properties. To conclude, N-acetyl-L-tryptophan may be considered as a novel neuroprotective therapy in Alzheimer’s disease.     

N-乙酰-L-色氨酸具有对新生鼠脑缺血/缺氧损伤的保护作用 

目的 探讨N-乙酰-L-色氨酸(L-NAT)对新生鼠脑缺血/缺氧损伤的保护作用.方法 出生第7天的沙土鼠90只,随机分为正常对照组、缺血/缺氧组和L-NAT组.制备脑缺血/缺氧损伤模型,L-NAT组在造模前30min腹腔注射L-NAT(5mg/kg).用Fluoro-Jade B(FJB)染色法观察细胞的死亡情况;用免疫荧光染色、Western blotting观察活化的Caspase-3和Caspase-9在各组的表达.结果 L-NAT可使缺血/缺氧损伤后FJB阳性细胞数量减少,并抑制缺血/缺氧后Caspase-3和Caspase-9的活化.结论 L-NAT对新生鼠脑缺血/缺氧损伤动物模型具有保护作用.     

N-乙酰-L-色氨酸减轻H2O2诱导小鼠海马神经元细胞凋亡

 目的 探讨N-乙酰-L-色氨酸(L-NAT)对海马神经元（PHN）缺血低氧损伤的影响。方法 用600μmol/L H2O2诱导PHN制备海马神经元细胞凋亡模型,采用免疫荧光染色检测caspase-3的表达,Rhodamine 123染色检测线粒体膜势能（ΔΨm）的改变,台盼蓝染色检测细胞存活率,比色法检测caspase-3、乳酸脱氢酶（LDH）的活性,Western blot检测caspase-3及凋亡诱导因子（AIF）和细胞色素C（CytC）等线粒体促凋亡因子在胞质蛋白和线粒体蛋白中的表达。结果 L-NAT可减轻H2O2所引起的细胞形态的死亡、存活率的降低、LDH的释放、caspase-3的激活、线粒体膜势能的丧失及AIF和CytC等线粒体促凋亡因子的释放。 结论 L-NAT能通过抑制caspase依赖性和非依赖性的细胞凋亡途径,减轻H2O2诱导的小鼠海马神经元的细胞损伤。     

N-乙酰-L-色氨酸对新生鼠脑缺血缺氧纹状体损伤的保护作用

目的 探讨N-乙酰-L-色氨酸(L-NAT)对新生鼠脑缺血缺氧纹状体损伤的保护作用.方法 用出生第7天的SD大鼠制备新生鼠脑缺血缺氧模型,HE染色观察纹状体的形态学变化;免疫荧光染色观察Caspase3、Bcl-2和Bax的表达情况.结果 与Sham组相比,HIE组纹状体中神经细胞排列紊乱,且数量明显减少,Caspase-3、Bcl-2、Bax的表达升高;HIE+L-NAT组纹状体细胞的损伤程度减轻,Bax、Caspase-3表达下降,Bcl-2的表达进一步升高.结论 L-NAT可能通过调节Bcl-2家族蛋白的表达减轻纹状体细胞的损伤程度,从而保护新生鼠脑缺血缺氧损伤.