鄭小影,孔維,趙淑敏,紀(jì)海茹,陳萌,馬衛(wèi)軍,韓莉,劉勝
丁苯酞預(yù)處理對(duì)腦缺血再灌注大鼠海馬微血管構(gòu)筑和自由基代謝的影響
鄭小影,孔維,趙淑敏△,紀(jì)海茹,陳萌,馬衛(wèi)軍,韓莉,劉勝
目的觀察局灶性腦缺血再灌注時(shí)大鼠海馬微血管構(gòu)筑和自由基代謝的變化,探討丁苯酞對(duì)其影響。方法54只SD大鼠按隨機(jī)數(shù)字表法分為丁苯酞預(yù)處理組、缺血再灌注組和假手術(shù)組,每組18只。線栓法制備大鼠右側(cè)大腦中動(dòng)脈栓塞模型,觀察神經(jīng)功能缺損評(píng)分和梗死體積;單寧酸-氯化鐵(TA-Fe)媒染法顯示海馬微血管,定量分析微血管密度(MVD)和微血管面積密度(MVA);比色法檢測(cè)海馬組織超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量。結(jié)果與缺血再灌注組相比,丁苯酞預(yù)處理組神經(jīng)功能缺損評(píng)分和梗死體積均減少,SOD活性升高、MDA含量下降,微血管數(shù)量增多,分支吻合成網(wǎng),MVD和MVA值明顯升高(P<0.01)。結(jié)論丁苯酞可改善海馬微血管分布,減輕自由基損傷,對(duì)局灶性腦缺血再灌注損傷有一定的預(yù)防性保護(hù)作用。
再灌注損傷;海馬;超氧化物歧化酶;丙二醛;丁苯酞;微血管密度;微血管面積密度
隨著社會(huì)的發(fā)展和生活節(jié)奏的加快,急性腦梗死患者逐年增多且呈現(xiàn)年輕化趨勢(shì)。其病理生理基礎(chǔ)主要是腦缺血再灌注損傷(cerebral ischemia re?perfusion injury,CIRI),這使尋找可靠藥物來抑制CIRI成為國內(nèi)外醫(yī)生面臨的主要難題之一。丁苯酞(3-n-butylphthalide,商品名恩必普,NBP)已被證明對(duì)CIRI有較好的治療作用[1]。但其作為預(yù)防用藥的效果和機(jī)制尚有待進(jìn)一步研究。本文通過觀察大鼠腦缺血再灌注時(shí)海馬微血管分布和超氧化物歧化酶(SOD)、丙二醛(MDA)代謝情況,探討丁苯酞對(duì)急性腦梗死的預(yù)防性保護(hù)作用及其可能機(jī)制。
1.1 材料與分組54只SPF級(jí)SD大鼠購自天津醫(yī)科大學(xué)實(shí)驗(yàn)動(dòng)物中心,體質(zhì)量200~240 g,按隨機(jī)數(shù)字表法分為丁苯酞預(yù)處理(NBP)組、缺血再灌注(IR)組和假手術(shù)(Sham)組,每組18只。丁苯酞購自石藥集團(tuán)恩必普藥業(yè)有限公司。NBP組給予40 mg·kg-1·d-1灌胃,Sham組和IR組給等容積的生理鹽水,共7 d。Mivnt圖像分析系統(tǒng)(山東);SOD、MDA、DAB顯色試劑盒(南京建成生物工程研究所);單寧酸、氯化鐵(市凱通化學(xué)試劑有限公司)。
1.2 方法
1.2.1 大鼠缺血再灌注模型制備大鼠適應(yīng)性飼養(yǎng)1周后,各組大鼠灌胃7 d,準(zhǔn)備漁線(一端涂凡士林,一端用記號(hào)筆做好標(biāo)記備用)。術(shù)前12 h禁食、自由飲水,IR組和NBP組采用Zea-Longa改良線栓法[2]制備右側(cè)大腦中動(dòng)脈閉塞(MCAO)2 h再灌注24 h模型。Sham組僅分離頸總、頸內(nèi)、頸外動(dòng)脈,不做插線處理。大鼠蘇醒后模型成功標(biāo)志為:右眼Horner征、行走時(shí)向左側(cè)傾倒或轉(zhuǎn)圈和提尾時(shí)左前肢屈曲內(nèi)收。不符合模型要求的剔除,并及時(shí)補(bǔ)遺。術(shù)后分籠保暖飼養(yǎng)。
1.2.2 神經(jīng)功能缺損評(píng)分參照Longa等[2]評(píng)分標(biāo)準(zhǔn),于腦缺血2 h再灌注24 h時(shí)對(duì)各組大鼠進(jìn)行神經(jīng)功能缺損評(píng)分。無神經(jīng)功能缺損癥狀0分;不能完全伸展對(duì)側(cè)前爪1分;向外側(cè)轉(zhuǎn)圈2分;向內(nèi)側(cè)傾倒3分;不能自發(fā)行走,意識(shí)喪失4分。1~3分留用,0分、4分者棄去,并及時(shí)補(bǔ)足。
1.2.3 腦梗死體積測(cè)定采用TTC染色法。大鼠缺血2 h再灌注24 h時(shí),每組取6只斷頭取腦。將新鮮的腦組織置于-20℃冰箱中速凍后,沿冠狀方向切成片厚約2 mm切片。在培養(yǎng)皿中將切片擺好,倒入2%TTC溶液,37℃恒溫箱避光孵育30 min,期間翻動(dòng)以保證切片均勻著色,甲醛固定后拍照。正常腦組織染成均勻玫瑰紅色,梗死區(qū)因缺血不著色而呈白色。圖像分析系統(tǒng)計(jì)算每片的梗死面積,梗死體積即為梗死面積之和與片厚的乘積,以梗死體積/全腦體積比值作為衡量參數(shù)。
1.2.4 海馬微血管的顯示及定量分析再灌注后24 h,每組大鼠取6只,采用含2%單寧酸的混合固定液灌注固定后取腦。震蕩切片機(jī)連續(xù)切片,片厚25 μm,隔2片取1片。TAFe聯(lián)合媒染法[3]顯示海馬微血管形態(tài)后光鏡下觀察并拍片。隨機(jī)讀取3個(gè)視野,Mivnt圖像分析系統(tǒng)定量分析各組大鼠海馬的微血管密度(microvesser density,MVD)和微血管面積密度(microvesser aera density,MVA),取平均值。
1.2.5 海馬組織SOD活性和MDA含量的測(cè)定再灌注24 h后,每組大鼠取6只,斷頭取腦。在冰盤上將右側(cè)海馬從新鮮腦組織分離出來并制成10%勻漿備用。操作流程和方法按試劑盒要求進(jìn)行。黃嘌呤氧化酶法測(cè)SOD活性,硫代巴比妥酸法測(cè)MDA含量。
1.3 統(tǒng)計(jì)學(xué)方法采用SPSS 16.0軟件處理,結(jié)果以表示,多組間比較采用方差分析,多重比較采用LSD-t檢驗(yàn);2組間比較用獨(dú)立樣本t檢驗(yàn)。P<0.05為差異有統(tǒng)計(jì)學(xué)意義。
2.1 各組大鼠神經(jīng)功能缺損評(píng)分Sham組無神經(jīng)功能缺損,IR組可見明顯的右側(cè)Horner征和行走時(shí)向左側(cè)轉(zhuǎn)圈現(xiàn)象,見圖1、2。與IR組相比,NBP組神經(jīng)功能缺損癥狀顯著減輕(P<0.01),見表1。
2.2 各組大鼠腦梗死體積百分比的比較Sham組腦組織染成均勻玫瑰紅色,IR組和NBP組均有不同范圍的蒼白色梗死灶。與IR組相比,NBP組的蒼白色范圍有較顯著的降低(P<0.01),見表1。
Fig.1Horner symptoms in the right圖1 右側(cè)Horner征
Fig.2Circling towards to the left圖2 向左轉(zhuǎn)圈
Tab.1Comparision of neurological scores and the infarction volume of rats in all three groups表1 各組大鼠神經(jīng)功能缺損評(píng)分、腦梗死體積比較(n=6)
Tab.1Comparision of neurological scores and the infarction volume of rats in all three groups表1 各組大鼠神經(jīng)功能缺損評(píng)分、腦梗死體積比較(n=6)
**P<0.01
組別Sham組IR組NBP組t神經(jīng)功能缺損評(píng)分0 2.99±0.36 1.42±0.19 9.431**腦梗死體積(%)0 9.66±0.97 3.99±0.69 11.670**
2.3 大鼠海馬微血管顯示及定量分析Sham組海馬微血管呈現(xiàn)空心管狀密集分布,發(fā)出分支并相互吻合成網(wǎng);IR組多數(shù)血管扭曲變形或閉合,分支及分支間吻合幾乎看不到,MVD、MVA均明顯降低,與Sham組相比,差異有統(tǒng)計(jì)學(xué)意義(P<0.01);NBP組的微血管數(shù)量和樹狀分支較多,形態(tài)自然,與IR組相比,MVD、MVA均增加(P<0.01),見表2、圖3。
Tab.2Comparison of MVD and MVA in Hippocampus of rats in all three groups表2 各組大鼠海馬的MVD與MVA變化(n=6)
Tab.2Comparison of MVD and MVA in Hippocampus of rats in all three groups表2 各組大鼠海馬的MVD與MVA變化(n=6)
**P<0.01;a與Sham組比較,b與IR組比較,P<0.01
組別Sham組IR組NBP組F MVD 47.04±3.15 10.88±0.97a 28.66±2.14ab 380.681**MVA 0.118 1±0.012 8 0.025 8±0.007 4a 0.066 8±0.007 7ab 137.898**
2.4 各組大鼠海馬組織SOD活性和MDA的含量與Sham組相比,IR組海馬組織的SOD活性明顯降低,而MDA含量顯著升高(P<0.01);NBP預(yù)處理有效上調(diào)了SOD活性,同時(shí)下調(diào)了MDA含量,與IR組比較差異有統(tǒng)計(jì)學(xué)意義(P<0.01),見表3。
Tab.3Changes of SOD and MDA in hippocampus of rats in all three groups表3 各組大鼠海馬組織的SOD活性與MDA含量比較(n=6)
Tab.3Changes of SOD and MDA in hippocampus of rats in all three groups表3 各組大鼠海馬組織的SOD活性與MDA含量比較(n=6)
**P<0.01;a與Sham組比較,b與IR組比較,P<0.01
組別Sham組IR組NBP組F SOD(U·mg-1·pro-1)140.84±3.07 95.22±3.35a 123.59±2.28ab 368.640**MDA(μmol·g-1·pro-1)9.03±0.84 15.10±0.75a 11.41±0.81ab 87.231**
Fig.3Microvascular architecture in hippocampus of rats in all groups(TA-Fe method,×200)圖3 各組大鼠海馬微血管構(gòu)筑(TA-Fe媒染法,×200)
急性腦梗死時(shí)血流急劇中斷可引起神經(jīng)功能缺損,早期溶栓又會(huì)加重這種損傷。因此,通過對(duì)動(dòng)物模型預(yù)防用藥來減輕或抑制這種缺血再灌注損傷的實(shí)驗(yàn)成為醫(yī)學(xué)科研人員一個(gè)主要研究方向。研究證實(shí)預(yù)防性應(yīng)用中藥黃芩莖葉總黃酮可有效減輕大鼠大腦中動(dòng)脈的CIRI時(shí)皮質(zhì)微血管損傷[4]、提高抗氧化能力,并抑制神經(jīng)元凋亡[5-6]。紀(jì)海茹等[7]應(yīng)用我國自主研發(fā)新藥丁苯酞(商品名稱:恩必普)預(yù)處理局灶性腦缺血再灌注大鼠也證實(shí)其可減輕CIRI造成的腦水腫并降低血腦屏障通透性。牛慧艷等[8]研究顯示丁苯酞氯化鈉注射液治療臨床急性缺血性卒中有較好療效。但丁苯酞作為臨床一級(jí)預(yù)防用藥的依據(jù)尚不完善,有待進(jìn)一步研究。
3.1 NBP對(duì)大鼠CIRI時(shí)海馬微血管構(gòu)筑的作用腦組織對(duì)缺血缺氧非常敏感,海馬作為最敏感部位之一,海馬微循環(huán)因其維持海馬血液與神經(jīng)元間的物質(zhì)交換而備受關(guān)注,微血管的數(shù)量、結(jié)構(gòu)和功能的完整性是有效血液供應(yīng)的保證。CIRI可以破壞毛細(xì)血管管壁完整性,從而改變其通透性,引發(fā)一系列的病理生理變化。顯示微血管的方法很多,而單寧酸-氯化鐵法[3]可更好地顯示微血管。用其觀察缺血再灌注大腦皮質(zhì)的微血管變化效果良好[4]。MVD、MVA是衡量微循環(huán)物質(zhì)交換功能狀態(tài)和局部血流量的主要參數(shù),本實(shí)驗(yàn)顯示Sham組海馬管狀微血管密集,分支很多且相互吻合成網(wǎng);而IR組毛細(xì)血管很少,分支及分支間的吻合少見,MVD、MVA均明顯降低;NBP組的毛細(xì)血管數(shù)量和分支增多,MVD、MVA均較IR組增加。說明丁苯酞對(duì)海馬CIRI的保護(hù)作用可能與丁苯酞能促進(jìn)CIRI的腦微血管側(cè)支循環(huán)的形成有關(guān),這與以往的報(bào)道一致[9]。
3.2 NBP對(duì)大鼠CIRI時(shí)海馬組織自由基代謝的影響CIRI的病理過程涉及許多因素,其中氧自由基占有重要地位。生理狀態(tài)下機(jī)體內(nèi)氧自由基的產(chǎn)生和清除處于動(dòng)態(tài)平衡狀態(tài),CIRI時(shí)產(chǎn)生的大量氧自由基可造成脂質(zhì)過氧化物蓄積,細(xì)胞膜受損,最終引起神經(jīng)功能缺損[10]。SOD是體內(nèi)重要的天然抗氧化酶,MDA是由氧自由基引發(fā)的脂質(zhì)過氧化產(chǎn)物,MDA的含量一定程度上可以反映機(jī)體的脂質(zhì)過氧化程度。因此,監(jiān)測(cè)CIRI時(shí)SOD活性和MDA含量成為評(píng)價(jià)此時(shí)機(jī)體內(nèi)氧化和抗氧化水平的經(jīng)典指標(biāo)。陳萌等[5]發(fā)現(xiàn)大鼠CIRI時(shí)SOD活性明顯下降,而MDA含量大幅上調(diào),說明CIRI時(shí)氧自由基致膜脂質(zhì)等損傷,從而引發(fā)一系列的腦細(xì)胞功能受損。本文用丁苯酞預(yù)處理實(shí)驗(yàn)大鼠發(fā)現(xiàn)NBP組較IR組SOD活性升高,MDA含量下降,提示丁苯酞可能通過調(diào)節(jié)自由基代謝來減輕CIRI。
綜上所述,本文通過分析丁苯酞預(yù)處理對(duì)大鼠局灶性CIRI海馬的微血管分布和自由基代謝的影響,證實(shí)其對(duì)CIRI有一定的預(yù)防性保護(hù)作用,為其成為臨床預(yù)防用藥提供了實(shí)驗(yàn)依據(jù)。
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(2014-11-24收稿2015-03-07修回)
(本文編輯李鵬)
Effects of 3-n-butylphthalide pretreatment on microvascular architecture and free radical metabolism in hippocampus induced by cerebral ischemia/reperfusion
ZHENG Xiaoying,KONG Wei,ZHAO Shumin△,JI Hairu,CHEN Meng,MA Weijun,HAN Li,LIU Sheng
Basic Medical College,Chengde Medical College,Chengde 067000,China△
ObjectiveTo observe microvascular architecture and free radical metabolism in hippocampus after focal cerebral ischemia/reperfusion and to explore the effect of NBP(3-n-butylphthalide).MethodsFifty-four SD rats were ran?domly divided into NBP pretreatment group,ischemia/reperfusion group and sham operation group(n=18 in each group).The model of middle cerebral artery occlusion(MCAO)was established by suture method.The neurological scores were counted and the volume of infarction was measured;TA-Fe method was applied to observe the microvascular architecture of hippo?campus,Mivnt image analysis system was used to analyze the microvessel density(MVD)and the microvessel area density(MVA)of hippocampus quantitatively;The activity of SOD and content of MDA were measured by colorimetric method.ResultsCompared to the ischemia reperfusion(IR)group,the neurological scores and the volume of infarction were decreased sharply in NBP group.What′s more,the activity of SOD,MVD and MVA were all enhanced but the content of MDA and the count of closed microvessels were both reduced(P<0.01).ConclusionNBP can improve microvascular architecture of hippocampus and reduce the free radical injury.There is a protective effect on hippocampus of rats who suffered focal cere?bral ischemia reperfusion.
reperfusion injury;hippocampus;superoxide dismutase;malondialdehyde;3-n-butylphthalide;microves?sel density;microvessel area density
R743
A
10.11958/j.issn.0253-9896.2015.08.010
河北省教育廳教育科學(xué)計(jì)劃項(xiàng)目(JYGH2010048)
承德醫(yī)學(xué)院基礎(chǔ)醫(yī)學(xué)院(郵編067000)
鄭小影(1980),女,碩士研究生,主要從事中樞神經(jīng)解剖方面研究
△通訊作者E-mail:zhaoshumin-2008@163.com