5-脂氧合酶在大鼠外科脑损伤模型脑组织中的表达及作用

目的 研究大鼠外科脑损伤(SBI)模型脑组织中5-脂氧合酶(5-LOX)表达的空间分布、细胞定位和随时间变化的规律,并探讨其在SBI发病中的可能作用机制.方法 将72只健康成年雄性SD大鼠随机分为假手术(Sham)组及SBI术后1 d(SBI-1d)组、3 d(SBI-3d)组、7 d(SBI-7d)组,每组18只.对SBI-1d、SBI-3d和SBI-7d组大鼠采用右侧额叶切除法建立SBI模型,Sham组大鼠只移除相应部位的颅骨,不伤及硬脑膜.采用干湿质量法测量损伤同侧、对侧脑组织的含水量;Garcia评分和杠杆平衡评分评估各组大鼠的神经行为学功能;免疫荧光化学染色确定5-LOX的空间分布及细胞定位;蛋白质印迹法检测5-LOX和核转录因子(NF)-κB的蛋白表达;生物化学法测定损伤区周围脑组织中超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量.结果 (1)与Sham组相比,SBI-1d和SBI-3d组大鼠损伤侧脑组织含水量增加(P＜0.05);SBI-1d、SBI-3d和SBI-Td组大鼠出现神经功能障碍(P＜0.01),SBI-Td组大鼠的Garcia评分较SBI-1d、SBI-3d组改善(P＜0.05).(2)5-LOX主要分布在损伤区周围的脑组织中,其中以神经元表达为主,星形胶质细胞和小胶质细胞也有表达.(3)与Sham组相比,SBI-1d和SBI-3d组大鼠损伤区周围脑组织中5-LOX、NF-κB表达增加(P＜0.05),而SBI-7d组两者表达低于SBI-1d和SBI-3d组(P＜0.05),其中5-LOX表达增加在SBI术后第1天最明显.(4)与Sham组相比,SBI-1d、SBI-3d和SBI-7d组大鼠损伤区周围脑组织中SOD活性降低(P＜0.05),SBI-1d和SBI-3d组MDA含量增加(P＜0.05).结论 SBI后,5-LOX主要表达于损伤区周围神经元,星形胶质细胞和小胶质细胞也有表达;且在SBI术后1d表达最多.5-LOX加重脑损伤可能与NF-κB表达增多以及氧化应激增加有关.

Cerebral expression and function of 5-lipoxygenase in surgical brain injury model of rats

Objective To investigate the spatial distribution,cell localization and time-dependent changes of 5-1ipoxygenase (5-LOX) expression in brain tissues of rats with surgical brain injury (SBI) and its role in the pathogenesis of SBI.Methods Seventy-two healthy male SD rats were randomly divided into Sham group,1-day post surgery (SBI-1d) group,3-day post surgery (SBI-3d) group and 7-day post surgery (SBI-Td) group,each group with 18 rats.SBI rat model was established by right frontal lobectomy in the SBI-1d,SBI-3d and SBI-7d groups,while rats in the Sham group only with the corresponding skull removed with the dura intact.Brain water content (BWC) of ipsilateral and contralateral brain tissues was measured by wet-dry weight formula.The neurobehavioral functions of all rats were evaluated by modified Garcia score and beam balance test.The spatial distribution and cellular location of 5-LOX were detected by imrmunofluorescence staining.The expressions of 5-LOX and NF-κB in the damaged brain tissues were detected by Western blotting analysis.The activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA) around the lesion areas were determined by biochemical method.Results (1) Compared with the Sham group,neurological dysfunction was significant in the SBI-1d,and SBI-3d and SBI-7d groups (P＜0.01),and the BWC of injured brain tissue of rats was significantly increased in the SBI-1d and SBI-3d groups (P＜0.05).The modified Garcia score in the SBI-Td group was significantly higher than that in the SBI-1d and SBI-3d groups (P＜0.05).(2) 5-LOX was mainly distributed around the lesion areas,which was mainly localized in the cytoplasm of neurons,followed by glial cells and microglia.(3) The expressions of 5-LOX and NF-κB were significantly increased in the SBI-1d and SBI-3d groups (P＜0.05) versus the Sham and SBI-7d groups.(4) Compared with the Sham group,the activity of SOD was significantly decreased in the other three groups (P＜0.05);while the content of MDA was significantly increased in the SBI-1d and SBI-3d groups (P＜0.05).Conclusion 5-LOX is mainly expressed in the neurons around the lesion areas after SBI,followed by glial cells and microglia,with the highest expression at 1 day after surgery.The mechanism by which 5-LOX aggravates brain injury may be related to increased expression of NF-κB and oxidative stress injury.