Xu Fa-Lin, Zhu Chang-Lian, Wang Xiao-Yang, Qiu Lin, Ji Ling, Cheng Xiu-Yong, Luan Bin
Department of Pediatrics, Third Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China.
Zhongguo Dang Dai Er Ke Za Zhi. 2006 Apr;8(2):137-40.
p53-induced apoptosis is crucial in the development of hypoxic-ischemia (HI) brain damage and neurodegenerative disorders. Some experimental research has shown that a synthetic inhibitor of p53 can protect neurons against apoptosis. This study aimed to explore the expression of p53 in neonatal mice following HI brain damage and the effect of p53 inhibitor (pifithrin-alpha, PFT-alpha) on brain damage.
HI was induced in 9-day-old mice pups by ligation of left carotid artery and 10% oxygen exposure for 55 minutes. The pups were sacrificed and the brains were taken out at 3, 8, 24, and 72 hrs post-HI. The brains were sectioned and stained with antibody against p53 and microtubule-associated protein 2 (MAP-2). PFT-alpha was injected intraperitoneally: in experiment 1, immediately after HI with different dosages (1, 2 and 8 mg/kg); in experiment 2, 2 mg/kg at different HI times (1 hr before HI, and immediately and 1 hr after HI). Control animals without HI received injections of 0.5% dimethyl sulfoxide. Brain damage was evaluated by gross morphology scoring at 72 hrs after HI.
The number of p53 positive cells in the cortex, hippocampus and striatum of the ipsilateral hemisphere increased significantly and peaked at 3-8 hrs post-HI when compared with those of contralateral hemisphere as well as normal controls. The positive cells distributed mainly in the MAP-2 negative area. Both different dosages and different injection time PFT-alpha treatment did not reduce the extent of brain damage.
The immunoactivity of p53 increased significantly as early as 3 hrs post-HI. The distribution area of p53 expression was consistent with that of brain damage. The p53 inhibitor PFT-alpha has no protective effects against HI brain damage in neonatal mice.
p53诱导的细胞凋亡在缺氧缺血性（HI）脑损伤和神经退行性疾病的发展过程中至关重要。一些实验研究表明，一种p53的合成抑制剂可保护神经元免受细胞凋亡。本研究旨在探讨HI脑损伤后新生小鼠中p53的表达情况以及p53抑制剂（pifithrin-α，PFT-α）对脑损伤的影响。
通过结扎左侧颈动脉并暴露于10%氧气中55分钟，在9日龄小鼠幼崽中诱导HI。在HI后3、8、24和72小时处死幼崽并取出大脑。将大脑切片并用抗p53和微管相关蛋白2（MAP-2）的抗体染色。腹腔注射PFT-α：在实验1中于HI后立即注射不同剂量（1、2和8mg/kg）；在实验2中于不同HI时间（HI前1小时、HI时及HI后1小时）注射2mg/kg。未经历HI的对照动物注射0.5%二甲基亚砜。在HI后72小时通过大体形态评分评估脑损伤。
与对侧半球以及正常对照相比，同侧半球皮质、海马和纹状体中p53阳性细胞数量显著增加，并在HI后3 - 8小时达到峰值。阳性细胞主要分布在MAP-2阴性区域。不同剂量和不同注射时间的PFT-α治疗均未减轻脑损伤程度。
早在HI后3小时，p53的免疫活性就显著增加。p53表达的分布区域与脑损伤区域一致。p53抑制剂PFT-α对新生小鼠的HI脑损伤无保护作用。
