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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1d(SBI-1d)组、3d(SBI-3d)组、7d(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-7d组大鼠出现神经功能障碍(P<0.01),SBI-7d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。
OBJECTIVE: To study the spatial distribution of 5-lipoxygenase (5-LOX) in brain tissue of rats with surgical brain injury (SBI) model and its location and change with time, and to explore its possible mechanism in the pathogenesis of SBI . Methods Seventy-two healthy male Sprague-Dawley rats were randomly divided into 4 groups: Sham group, SBI-1d group, SBI-3d group and SBI-7d group only. SBI model was established by right frontal lobectomy in SBI-1d, SBI-3d and SBI-7d rats, Sham rats were only removed the corresponding part of the skull, do not hurt the dura. The water content of injured ipsilateral and contralateral brain tissues was measured by wet-dry mass method. The neurobehavioral function of rats in each group was evaluated by Garcia score and lever balance score. The spatial distribution and cell localization of 5-LOX were determined by immunofluorescence staining. The protein expression of 5-LOX and NF-κB was detected by Western blotting. The activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA) in brain tissue around the lesion area were determined by biochemistry method. Results Compared with Sham group, the water content in injured side of SBI-1d group and SBI-3d group increased (P <0.05), and the neurological function in SBI-1d, SBI-3d and SBI-7d groups (P <0.01). The Garcia score of SBI-7d group improved compared with SBI-1d group and SBI-3d group (P <0.05). (2) 5-LOX mainly distributed in the brain tissue around the injured area, among which the neurons were mainly expressed, astrocytes and microglia were also expressed. (3) Compared with Sham group, the expression of 5-LOX and NF-κB increased (P <0.05) in SBI-1d and SBI-3d groups, while the expression in SBI-7d group was lower than that in Sham group SBI-1d and SBI-3d group (P <0.05). The increase of 5-LOX expression was the most obvious on the first day after SBI. (4) Compared with Sham group, SOD activity in brain tissue of SBI-1d, SBI-3d and SBI-7d groups decreased (P <0.05), and MDA content in SBI-1d and SBI-3d groups increased P <0.05). Conclusions After SBI, the expression of 5-LOX is mainly expressed in the peripheral neurons, astrocytes and microglial cells in the injured area, and the expression is highest at 1 day after SBI. 5-LOX increased brain damage may be related to increased expression of NF-κB and increased oxidative stress.