雌激素对去卵巢大鼠不同脑区淀粉样β蛋白前体蛋白β位点裂解酶表达的影响(英文)

Effects of estrogen on the expression of beta-amyloid precursor protein cleaving enzyme in different cerebral regions ofovariectomized rats

背景:脑中雌激素可调节淀粉样β蛋白前体蛋白的代谢与β淀粉样蛋白的产生。了解雌激素与淀粉样β蛋白前体蛋白代谢以及关键酶淀粉样β蛋白前体蛋白β位点裂解酶的关系,对研究轻度认知障碍、阿尔茨海默病的发病原因具有重要作用。目的:利用大鼠卵巢切除模型观察内外源性雌激素缺乏及补充外源性雌激素对大鼠脑皮质区和海马CA1区淀粉样β蛋白前体蛋白β位点裂解酶表达以及血清雌激素含量的影响。设计:完全随机对照实验。单位:青岛大学医学院附属医院脑血管病研究所,青岛市市立医院病理科。材料:实验于2003-01/12在青岛大学医学院附属医院脑病防治重点实验室完成。选择健康雌性Wistar大鼠21只,随机分为3组,每组7只。①卵巢切除组:制备大鼠双侧卵巢切除模型。②卵巢切除后补充外源性雌激素治疗组(雌激素组):卵巢切除后给予苯甲酸雌二醇(1mg/kg),每7d皮下注射1次,共4次。③假手术对照组:手术过程与卵巢切除组相同,但不切除卵巢,不补充雌激素。方法:①第28天时,大鼠在麻醉状态下取脑组织备用,制备冠状切片,用于免疫荧光标记细胞化学染色观察。②激光共聚焦显微镜下观察皮质区、海马CA1区红色荧光标记细胞数量。③体内雌激素水平检测:大鼠眼动脉取血1.5mL,离心取上清备用,运用放射免疫法检测大鼠血清中雌激素含量。主要观察指标:①免疫荧光标记细胞化学法观察大鼠脑皮质区、海马CA1区淀粉样β蛋白前体蛋白β位点裂解酶免疫荧光细胞数的变化。②放免法测量大鼠血清雌激素含量的变化。结果:21只大鼠均进入结果分析。①卵巢切除组大鼠皮质区、海马CA1区淀粉样β蛋白前体蛋白β位点裂解酶阳性细胞数显著高于对照组和雌激素组[皮质区:(20.00±5.16),(5.71±3.14),(4.00±4.61)个/视野;海马CA1区:(17.14±4.45),(6.85±1.95),(5.14±5.52)个/视野,P均<0.01]。②卵巢切除组血液雌激素含量显著低于对照组和雌激素组[(5.31±0.85),(22.94±9.48),(21.30±7.62)ng/L,P均<0.01]。③雌激素组各观察部位淀粉样β蛋白前体蛋白β位点裂解酶表达阳性细胞数和血液雌激素含量与对照组接近(P均>0.05)。结论:采用双侧卵巢切除的方法,造成大鼠体内雌激素缺乏,引起大鼠脑内皮质区、海马CA1区淀粉样β蛋白前体蛋白β位点裂解酶表达增多。给予卵巢切除大鼠补充外源性雌激素,其海马CA1区、皮质区淀粉样β蛋白前体蛋白β位点裂解酶表达显著减少,说明体内外雌激素含量的变化可影响大鼠皮质和海马区域淀粉样β蛋白前体蛋白β位点裂解酶表达。

BACKGROUND： Estrogen has a role in regulating the metabolism of beta-amyloid precursor protein and the production of beta-amyloid protein. It is important for studies on etiological factors of mild cognitive impairment and Alzheimer＇s disease to understand the relationship of estrogen with the metabolism of betaamyloid precursor protein and beta-amyloid precursor protein cleaving enzyme （BACE）. OBJECTIVE： To observe the effects of endogenous and exogenous estrogen deficiency and exogenous estrogen supplement on BACE expression in the cortex and hippocampal CA1 of ovariectomized rats as well as the level of estrogen in serum. DESIGN： A completely randomized and controlled experiment. SETTING： Institute of Cerebrovascular Diseases, Affiliated Hospital of the Medical College of Qingdao University; Department of Pathology, Qingdao Municipal Hospital. MATERIALS： The experiment was carried out in the Institute of Cerebrovascular Diseases, Affiliated Hospital of the Medical College of Qingdao University, from January to December 2003. Totally 21 Wistar rats were randomized into 3 groups： ovariectomy group, estrogen group （supplement of benovocylin at a dose of 1 mg,/kg via subcutaneous injection following ovarieetomy every seven days for four times）, and sham-operation control group （no ovariectomy or supplement of estrogen）. METHODS： ① On day 28, rats were killed under anesthesia to take out brain tissues and make coronary sections for histochemical observation by using immunofluorescence staining. ② Under the laser confocal microscope, we observed the number of red fluorescence-labeled cells in the cortex and hippocampal CA1 region. ③ Estrogen level： Blood sample of 1.5 mL was collected from rats＇ ophthalmic artery to prepare supernatant via centrifugation for examining the estrogen level in serum with radioimmunoassay.MAIN OUTCOME MEASURES： ①The number of BACE positive neurons in the cortex and hippocampal CA1 regions; ② the content of estrogen in serum. RESULTS： All the rats entered the result analysis. ① Compared with that of control and estrogen groups, the number of BACE positive neurons in the cortex and hippocampal CA1 of ovariectomy group increased significantly （cortex： 20.00＋5.16, 5.71＋3.14, 4.00＋4.61; hippocampalCAl： 17.14＋4.45, 6.85＋1.95, 5.14＋5.52, all P 〈 0.01）.② The content of estrogen in ovarieetomy group decreased obviously as compared with that of control and estrogen groups [（5.31＋0.85）, （22.94＋9.48）, （21.30＋7.62） ng/L, all P 〈 0.01]. ③ Estrogen group and control group did not significantly differ in the number of BACE positive neurons in each encephalic region observed and the content of estrogen （P 〉 0.05）. CONCLUSION： Bilateral ovariectomy results in estrogen deficiency and an increased expression of BACE in the cortex and hippocampal CA1 regions of rats, which can be inhibited by supplement of estrogen. It suggests that the variation of estrogen can affect the expression of BACE in the cortex and hippocampal CAI of rats.