鸢尾素对新生大鼠缺氧缺血性脑损伤的作用及机制

Effect of irisin on hypoxic-ischemic brain damage in neonatal rats

摘要:

目的 探索鸢尾素对新生大鼠缺氧缺血性脑损伤的作用和机制。方法 将248只7日龄Sprague-Dawley大鼠随机分为假手术组、模型组、鸢尾素干预低剂量组及高剂量组（n=62）。模型组和鸢尾素干预组大鼠行右侧颈总动脉结扎后再行缺氧处理，建立缺氧缺血脑损伤模型。假手术组只分离右侧颈总动脉而不做结扎和缺氧处理。高、低剂量组大鼠分别于侧脑室注射0.15 μg、0.30 μg重组鸢尾素多肽，模型组及假手术组注射等量PBS。采用水迷宫实验检测各组大鼠神经行为学差异；采用TTC染色、苏木精-伊红染色和TUNEL染色检测各组大鼠脑组织病理改变；采用Western blot检测凋亡相关分子cleaved-caspase-3（CC3）及BCL-2/BAX的表达差异。结果 与假手术组相比，模型组大鼠潜伏期延长，穿越平台次数减少（P < 0.05）；高剂量组大鼠潜伏期较模型组缩短，穿越平台次数较模型组增加（P < 0.05）。与假手术组比较，模型组大鼠右侧大脑半球出现大面积梗死，细胞核固缩及核裂解明显增多；高剂量组大鼠与模型组大鼠相比，右侧大脑半球梗死面积减少，细胞核固缩及核裂解减少。模型组大鼠右侧大脑皮层及海马区细胞凋亡率明显高于假手术组，高剂量组细胞凋亡率明显低于模型组（P < 0.05）。造模后24 h及48 h，假手术组CC3水平明显低于模型组（P < 0.05）；高剂量组CC3水平明显低于模型组，BCL-2/BAX值明显高于模型组（P < 0.05）。低剂量组上述实验指标及脑组织病理变化情况与模型组类似。结论 鸢尾素可以有效减轻新生大鼠缺氧缺血性脑损伤，且疗效与鸢尾素使用剂量有关，其作用机制可能与减少大脑皮层及海马区域细胞凋亡相关。

Abstract:

Objective To study the effect and mechanism of action of irisin on hypoxic-ischemic brain damage in neonatal rats. Methods A total of 248 7-day-old Sprague-Dawley rats were randomly divided into a sham-operation group, a model group, and low-and high-dose irisin intervention groups (n=62 each). The rats in the model and irisin intervention groups were given hypoxic treatment after right common carotid artery ligation to establish a model of hypoxic-ischemic brain damage. Those in the sham-operation group were given the separation of the right common carotid artery without ligation or hypoxic treatment. The rats in the high-and low-dose irisin intervention groups were given intracerebroventricular injection of recombinant irisin polypeptide at a dose of 0.30 μg and 0.15 μg respectively. Those in the model and sham-operation groups were given the injection of an equal volume of PBS. The water maze test was used to compare neurological behaviors between groups. TTC staining, hematoxylin-eosin staining and TUNEL staining were used to observe histopathological changes of the brain. Western blot was used to measure the expression of the apoptosis-related molecules cleaved-caspase-3 (CC3), BCL-2 and BAX. Results Compared with the sham-operation group, the model group had a significant increase in latency time and a significant reduction in the number of platform crossings (P < 0.05). Compared with the model group, the high-dose irisin intervention group had a significant reduction in latency time and a significant increase in the number of platform crossings (P < 0.05). Compared with the sham-operation group, the model group had massive infarction in the right hemisphere, with significant increases in karyopyknosis and karyorrhexis. Compared with the model group, the high-dose irisin intervention group had a smaller infarct area of the right hemisphere, with reductions in karyopyknosis and karyorrhexis. The model group had a significantly higher apoptosis rate of cells in the right cerebral cortex and the hippocampus than the sham-operation group. The high-dose irisin intervention group had a significantly lower apoptosis rate than the model group (P < 0.05). At 24 and 48 hours after modeling, the sham-operation group had a significantly lower level of CC3 than the model group (P < 0.05). Compared with the model group, the high-dose irisin intervention group had a significantly lower level of CC3 and a significantly higher BCL-2/BAX ratio (P < 0.05). The low-dose irisin intervention group had similar laboratory markers and histopathological changes of the brain to the model group. Conclusions Irisin can alleviate hypoxic-ischemic brain damage in neonatal rats in a dose-dependent manner, possibly by reducing cell apoptosis in the cerebral cortex and the hippocampus.