計(jì)莉強(qiáng) 姚曉霖 許廣艷
[摘要] 目的 觀察黃芪多糖對2型糖尿病ZDF大鼠血糖及肝臟脂代謝的影響。 方法 選取30只成年雄性ZDF大鼠,隨機(jī)分為模型組、APS低劑量、APS中劑量組、APS高劑量組和二甲雙胍組;另取6只成年雄性ZDF(fa/+)大鼠作為正常組。實(shí)驗(yàn)組灌胃給予相應(yīng)劑量藥物,模型組和正常組灌胃給予生理鹽水溶液,測定各組ZDF大鼠體重、空腹血糖;肝脂代謝指標(biāo):TC、TG、LDL-C、HDL-C含量;肝損傷指標(biāo):AST、ALT活性;肝臟病理學(xué)檢測,從而探討APS對2型糖尿病ZDF大鼠血糖及肝臟脂代謝的影響。 結(jié)果 給藥前實(shí)驗(yàn)組大鼠體重、空腹血糖顯著增高,TC、TG、LDL-C顯著增加,符合糖尿病癥狀,且肝損傷存在一定程度損傷;予APS后各實(shí)驗(yàn)組大鼠體重較模型組顯著降低(P<0.05),同時(shí)與給藥前相比體重顯著性降低(P<0.05);空腹血糖較模型組顯著性降低(P<0.05),其中黃芪多糖大劑量降血糖作用最為顯著(P<0.01),與給藥前相比得出同樣的結(jié)論;各實(shí)驗(yàn)組大鼠TC、TG、LDL-C較模型組均有降低趨勢,其中APS高劑量組TC、TG、LDL-C含量下降最顯著(P<0.05);肝損傷方面,各給藥組大鼠ALT、AST較模型組均有降低趨勢,且APS高劑量組最為顯著(P<0.05);肝臟HE結(jié)果顯示模型組細(xì)胞核皺縮,胞質(zhì)呈網(wǎng)絲狀,細(xì)胞間存在明顯脂滴沉積;予APS后,肝臟細(xì)胞形態(tài)趨于正常,部分細(xì)胞內(nèi)存在細(xì)小脂滴,肝小葉結(jié)構(gòu)正常,肝細(xì)胞索呈放射狀排列。 結(jié)論 黃芪多糖通過降血糖和糾正肝臟脂代謝紊亂,改善肝臟脂滴沉積,對抗糖尿病引起的肝損傷,從而起到抗2型糖尿病的作用。
[關(guān)鍵詞] 黃芪多糖;2型糖尿病;脂代謝;肝臟
[中圖分類號] R285.5 [文獻(xiàn)標(biāo)識(shí)碼] A [文章編號] 1673-9701(2017)26-0030-05
Effects of astragalus polysaccharides on blood glucose and liver lipid Metabolism in ZDF Rats with type 2 diabetes mellitus
JI Liqiang1 YAO Xiaolin2 XU Guangyan3
1.Department of Pharmacy, the First People's Hospital of Yuhang District in Hangzhou City, Hangzhou 311100, China; 2.Department of Urology, the First Affiliated Hospital of Zhejiang University Medical College, Hangzhou 310003, China; 3.Department of Pharmacy, PLA 117 Hospital, Hangzhou 310000, China
[Abstract] Objective To observe the effect of astragalus polysaccharides on blood glucose and liver lipid metabolism in ZDF rats with type 2 diabetes mellitus. Methods 30 adult male ZDF rats were selected and randomly divided into model group, APS low dose group, APS middle dose group, APS high dose group and metformin group. 6 adult male ZDF (fa/+) rats were selected as normal group. The rats in the experimental group were treated with corresponding dose of the drug. The model group and normal group were given the same dose of saline solution. The body weight, fasting blood glucose, liver lipid metabolism indexes(TC, TG, LDL-C and HDL-C), liver damage indexes(AST, ALT activity) and liver pathology detection of ZDF rats in each group were determined, explored the influence of APS on blood glucose and liver lipid metabolism in type 2 diabetes ZDF rats. Results The body weight, fasting blood glucose, TC, TG and LDL-C were significantly increased in the experimental group before drug administration, which was accorded with the symptoms of diabetes mellitus and there was a certain degree of damage to liver. After administration of APS, the body weight of each experimental group was significantly lower than that of the model group and that before drug treatment(P<0.05). Fasting blood glucose in each treatment group was significantly lower than that in model group, and the high dose of astragalus polysaccharides had the most significant hypoglycemic effect, which got the same conclusion to that before administration. The levels of TC, TG and LDL-C in each experimental group were lower than those in the model group, and the decrease of TC, TG, LDL-C in APS high dose group was the most significant(P<0.05). The ALT and AST in each treatment group were lower than those in the model group, and the decrease in APS high dose group was the most significant(P<0.05). Liver HE results showed that there was shrinkage of nucleus in the model group, and the cytoplasm was filamentous, and there was significant lipid deposition between cells. After the administration of APS,the liver cell morphology tended to normal, and there were small lipid droplets in some cells, with normal liver lobular structure and radially arranged in hepatic cords. Conclusion Astragalus polysaccharides can improve liver lipid deposition and prevent hepatic injury caused by diabetes mellitus by lowering blood sugar and correcting liver lipid metabolism disorder, so as to play an role of anti-type 2 diabetes mellitus.endprint
[Key words] Astragalus polysaccharides; Type 2 diabetes; Lipid metabolism; Liver
2型糖尿病患者多為脂代謝紊亂,主要包括高甘油三酯血癥、高密度脂蛋白降低、低密度脂蛋白增加,慢性高血糖和高脂血癥可導(dǎo)致糖尿病并發(fā)癥,如動(dòng)脈粥樣硬化和脂肪肝,因此研究糖尿病肝脂代謝紊亂具有非常重要的臨床價(jià)值。黃芪多糖(Astra-galus polys-aecharides,APS)是從中藥黃芪中提取的一種大分子生物活性物質(zhì),目前研究認(rèn)為其具有抗氧化與加強(qiáng)免疫力等作用[1-3]。本文通過觀察APS對2型糖尿病ZDF大鼠肝臟代謝功能的作用,旨在分析APS在2型糖尿病治療中的臨床價(jià)值,以期為防治2型糖尿病提供相關(guān)參考。
1 材料與方法
1.1 動(dòng)物與飼料
選擇體重約為(200±20) g成年雄性ZDF大鼠30只,體重約為(200±20)g,成年雄性ZDF(fa/+)大鼠6只,SPF級,購于北京維通利華實(shí)驗(yàn)動(dòng)物有限公司。飼養(yǎng)條件:由浙江中醫(yī)藥大學(xué)動(dòng)物實(shí)驗(yàn)研究中心飼養(yǎng),許可證:SYXK(浙)2016-0115。溫度(22±1)°C,濕度50%~70%,光照:150-200Lx,每12小時(shí)明暗交替,換風(fēng)次數(shù)15~20次/h。噪音:<50 dB。每籠飼養(yǎng)2只大鼠并標(biāo)記編號。普通飼料:Co60輻照滅菌大鼠標(biāo)準(zhǔn)顆粒飼料。高脂高糖飼料:在基礎(chǔ)飼料上加入10%蛋黃、10%蔗糖、10%豬油、0.25%膽固醇;并用Co60輻照滅菌。
1.2主要試劑和設(shè)備
黃芪多糖:浙江中醫(yī)藥大學(xué)藥學(xué)院提供;格華止(鹽酸二甲雙胍片):上海施貴寶制藥公司,批號:1605 089;Rat insulin ELISA Kit 10-1250-01:Mercodia AB生產(chǎn),批號:21759;生化測定試劑盒:南京建成生物有限公司,批號 20160623;Quo-Test A1C HbA1c Reag-ent Kit:Quotient Diagnostics Ltd生產(chǎn),批號:020166;全自動(dòng)生化儀:日本日立株式會(huì)所生產(chǎn),型號:7020;糖化血紅蛋白測定儀:Quotient Diagnostics Ltd生產(chǎn)。
1.3 模型誘導(dǎo)
取36只SPF級雄性ZDF(fa/fa)大鼠,適應(yīng)性喂養(yǎng)1周后,采用高脂飼料誘導(dǎo),2周后采用眼眶取血方法測定血生化指標(biāo),分組給藥后,喂普通飼料。另取6只ZDF(fa/+)大鼠,予普通飼料。
1.4 糖尿病ZDF大鼠分組與給藥
將ZDF(fa/fa)大鼠按體重和血糖值隨機(jī)分組,即模型組、APS低劑量(200 mg/kg)組、APS中劑量組(400 mg/kg)組、APS高劑量組(800 mg/kg)、二甲雙胍組(200 mg/kg),每組6只,各實(shí)驗(yàn)組分別灌胃給予相應(yīng)劑量藥物,模型組和ZDF(fa/+)正常組大鼠灌胃給予生理鹽水溶液10 mL/kg,每日1次,連續(xù)8周。
1.5 測定指標(biāo)
分別在給藥前和末次給藥后,8 h禁食不禁水,于次日清晨空腹眼眶取血。給藥結(jié)束后心臟取血處死,分離血清后分別測定TC、TG、AST、ALT、LDL-C、HDL-C,由浙江中醫(yī)藥大學(xué)動(dòng)物實(shí)驗(yàn)中心測定;取肝臟組織,4%甲醛固定,制備病理切片,由浙江中醫(yī)藥大學(xué)動(dòng)物實(shí)驗(yàn)中心完成病理片拍攝。
1.6 統(tǒng)計(jì)學(xué)方法
采用SPSS17.0軟件進(jìn)行統(tǒng)計(jì)分析,計(jì)量資料以均數(shù)±標(biāo)準(zhǔn)差(x±s)表示。計(jì)量資料若方差齊,則采用LSD檢驗(yàn)兩兩比較;若方差不齊,其差異性則采用H-G檢驗(yàn),P<0.05表示差異有顯著性,P<0.01為差異有極顯著統(tǒng)計(jì)學(xué)意義。
2結(jié)果
2.1黃芪多糖對糖尿病ZDF大鼠體重和血糖的影響
見表1。給藥前正常組大鼠體重顯著低于各實(shí)驗(yàn)組(P<0.01),且各實(shí)驗(yàn)組間體重?zé)o明顯差異;給藥結(jié)束后,各實(shí)驗(yàn)組大鼠體重較模型組顯著降低(P<0.05),其中黃芪多糖組呈量效關(guān)系,同時(shí)與給藥前相比體重顯著性降低(P<0.05),黃芪多糖高劑量組降低最顯著(P<0.01)。與正常組比較,各實(shí)驗(yàn)組空腹血糖升高具有顯著性(P<0.01);給藥結(jié)束后,實(shí)驗(yàn)組空腹血糖明顯低于模型組,差異有統(tǒng)計(jì)學(xué)意義,其中黃芪多糖高劑量組降血糖作用最為顯著(P<0.01);同樣,與給藥前相比,黃芪多糖高劑量組大鼠血糖下降最為明顯(P<0.01)。
2.2黃芪多糖對糖尿病ZDF大鼠TC、TG的影響
見表2。正常組TC、TG在給藥前顯著低于各實(shí)驗(yàn)組(P<0.01);給藥結(jié)束后,各實(shí)驗(yàn)組大鼠TC、TG較模型組均有一定程度降低,其中黃芪多糖高劑量組TC、TG下降最顯著(P<0.01);與給藥前相比,給藥后黃芪多糖組大鼠TC、TG均有一定程度降低,其中高劑量組下降最顯著(P<0.05)。
2.3黃芪多糖對糖尿病ZDF大鼠HDL-C、LDL-C的影響
見表3。給藥前正常組大鼠HDL-C與LDL-C含量明顯低于各實(shí)驗(yàn)組(P<0.05),且與模型組相比各給藥組HDL-C與LDL-C含量均無顯著性差異;給藥結(jié)束后,各給藥組大鼠與模型組相比HDL-C無顯著性差異。與正常組相比,各實(shí)驗(yàn)組LDL-C顯著性升高(P<0.05);給藥結(jié)束后,與模型組相比,黃芪多糖高劑量組LDL-C顯著下降(P<0.05),其余給藥組雖有一定程度降低,但差異無統(tǒng)計(jì)學(xué)意義;與給藥前相比,給藥后黃芪多糖高劑量組LDL-C含量下降顯著(P<0.05)。
2.4黃芪多糖對糖尿病ZDF大鼠ALT、AST的影響
見表4。正常組大鼠在給藥前ALT明顯低于各實(shí)驗(yàn)組(P<0.01),且各實(shí)驗(yàn)組間無顯著性差異;給藥結(jié)束后,正常組大鼠ALT顯著低于各實(shí)驗(yàn)組(P<0.01),各給藥組大鼠ALT較模型組顯著降低(P<0.05);與給藥前相比,給藥后黃芪多糖組ALT均有一定程度降低(P<0.05)。給藥前,各組大鼠AST無顯著差異;給藥結(jié)束后,與模型組相比,黃芪多糖中、高劑量組AST顯著降低(P<0.05),其余給藥組雖有一定程度降低,但差異無統(tǒng)計(jì)學(xué)意義。endprint
2.5黃芪多糖對糖尿病ZDF大鼠肝臟病理結(jié)構(gòu)的影響
見封三圖3。正常組ZDF大鼠肝臟細(xì)胞分布均勻,形態(tài)正常,肝細(xì)胞索呈放射狀排列,細(xì)胞無明顯病變現(xiàn)象,見封三圖3A。而模型組ZDF大鼠肝臟細(xì)胞核皺縮,胞質(zhì)呈網(wǎng)絲狀,細(xì)胞間存在明顯脂滴沉積,見封三圖3B。C、D黃芪多糖組大鼠肝臟部分細(xì)胞內(nèi)見細(xì)小脂滴空泡化,肝細(xì)胞索呈放射狀排列,見封三圖3C和封三圖3D,其中黃芪多糖高劑量組大鼠肝臟細(xì)胞形態(tài)正常,肝小葉結(jié)構(gòu)正常,肝細(xì)胞索呈放射狀排列,見封三圖3E。二甲雙胍組大鼠肝臟部分細(xì)胞內(nèi)存在脂滴空泡化,肝細(xì)胞索狀結(jié)構(gòu)清晰,見封三圖3F。
3 討論
糖尿病是繼癌癥、心腦血管疾病之后危害人類健康的第三大疾病。據(jù)國際糖尿病聯(lián)盟(International Diabetes Federation,IDF)統(tǒng)計(jì),2013年全球糖尿病患者總數(shù)約為3.82億,預(yù)計(jì)2035年將達(dá)到5.92億[4]。2型糖尿病的發(fā)病原因和機(jī)制非常復(fù)雜,包括葡萄糖代謝、脂代謝和能量代謝紊亂,因胰島β細(xì)胞功能缺陷而導(dǎo)致的胰島素分泌減少(或相對減少)或由于胰島素抵抗(或兩者共同存在)所致的胰島素在機(jī)體內(nèi)調(diào)控葡萄糖代謝能力的下降[5]等。針對發(fā)病原因,目前臨床上廣泛應(yīng)用于治療2型糖尿病的藥物有雙胍類、磺酰脲類、噻唑烷二酮類、α-葡萄糖苷酶抑制劑等,但有部分患者服用后會(huì)產(chǎn)生毒副作用,如肝毒性、低血糖癥、體重增加、浮腫、胃腸道功能紊亂[6]等,因此患者用藥受到限制[7]。
糖尿病動(dòng)物模型是用于研究糖尿病及其并發(fā)癥發(fā)生發(fā)展的分子機(jī)制及新的治療措施的重要手段[8]。本實(shí)驗(yàn)采用的是ZDF(Zucker diabetic fatty rat)自發(fā)性糖尿病大鼠模型——一種由于編碼瘦素Leprfa等位基因突變形成的自發(fā)性純合子糖尿病大鼠,其特點(diǎn)是具有肥胖、高胰島素血癥、高血糖以及高甘油三酯和高脂肪酸等特征,病理生理與人類糖尿病相似。作為FDA糖尿病藥物研發(fā)指南所述的2型糖尿病常用動(dòng)物模型之一[9],目前作為研究糖尿病的病因和發(fā)病機(jī)制研究的動(dòng)物載體被國內(nèi)外廣泛應(yīng)用。其在6周齡時(shí)便出現(xiàn)胰島素抵抗的特點(diǎn),10~12周齡時(shí)表現(xiàn)出穩(wěn)定的高血糖狀態(tài)[10]。本實(shí)驗(yàn)采用高脂飼料誘導(dǎo)2周后,造模大鼠體重顯著增加,空腹血糖≥16.7 mmol/L,而且TC、TG和LDL-C明顯升高,肝臟生化指標(biāo)ALT、AST顯著升高,肝臟病理亦符合糖尿病肝臟脂代謝紊亂標(biāo)準(zhǔn)。
中藥黃芪是常用的補(bǔ)氣中藥,具有補(bǔ)氣健脾、益衛(wèi)固表、升陽舉陷、利水消腫、托毒生肌等作用[11]。研究發(fā)現(xiàn),含黃芪的復(fù)方、黃芪單藥或黃芪提取液能降低血黏度和甘油三酯,提高血管中NO水平,減少內(nèi)皮損傷,改善微循環(huán),在糖尿病足、糖尿病微血管病變的治療方面有明顯的療效[12-13],目前在糖尿病、心血管疾病的臨床輔助治療中中藥黃芪已廣泛應(yīng)用。黃芪多糖(Astragalus polysaccharide,APS)是黃芪中最有效的成分之一,其主要生物活性表現(xiàn)為增強(qiáng)機(jī)體免疫功能、抗腫瘤、抗病毒、抗氧化、抗衰老、神經(jīng)修復(fù)、降低腦缺血損傷等功效[14]。
肝臟是人體代謝的主要器官,是糖、蛋白質(zhì)和脂肪三大代謝的中心[15],直接參與糖在體內(nèi)的代謝過程,在機(jī)體的儲(chǔ)存、分布和血糖的調(diào)節(jié)方面起重要作用,與2型糖尿病的發(fā)生和發(fā)展密切相關(guān)。本實(shí)驗(yàn)HE染色結(jié)果顯示,正常組ZDF大鼠肝臟細(xì)胞分布均勻,細(xì)胞無明顯病變現(xiàn)象,而模型組大鼠細(xì)胞核皺縮,細(xì)胞間存在明顯脂滴積累,而經(jīng)黃芪多糖干預(yù)后脂滴積累現(xiàn)象均出現(xiàn)一定程度的改善,表明黃芪多糖在一定程度上可改善肝臟脂滴沉積。
糖尿病肝脂代謝紊亂中心環(huán)節(jié)為胰島素抵抗[16]。當(dāng)機(jī)體的胰島素受體發(fā)生缺陷,體內(nèi)的糖元無法有效利用,胰島素代償性分泌增加,脂肪的抗脂解作用減少,脂蛋白酶的活性增加,脂肪分解加速,血漿FFA和肝臟合成TG增加,從而促進(jìn)機(jī)體發(fā)生肝臟胰島素抵抗[17-19]。且TC、TG水平增高與2型糖尿病病情和病程有關(guān)。本實(shí)驗(yàn)研究表明,ZDF模型大鼠TC、TG含量增加,同時(shí)肝臟ALT、AST活力異常升高,表明2型糖尿病可導(dǎo)致脂代謝紊亂,且可導(dǎo)致肝細(xì)胞實(shí)質(zhì)損傷。黃芪多糖能明顯降低2型糖尿病ZDF大鼠的血糖、TC、TG和HDL-C含量,表明黃芪多糖能夠調(diào)節(jié)降血糖和改善脂代謝紊亂作用。
血清AST、ALT等酶的活性可靈敏反映肝細(xì)胞損傷、壞死的程度[20],本文中ZDF模型大鼠出現(xiàn)AST、ALT增高趨勢,其中ALT顯著性增加,表明此時(shí)ZDF模型大鼠肝臟出現(xiàn)一定程度損傷。黃芪多糖給藥后,AST、ALT含量明顯低于模型組,表明黃芪多糖能保護(hù)肝臟細(xì)胞,挽救肝損傷。
綜上所述,黃芪多糖可顯著改善ZDF大鼠體重、空腹血糖、TC、TG、LDL-C含量,降低肝損傷特異性指標(biāo)AST、ALT的含量,減輕ZDF大鼠肝臟細(xì)胞空泡程度,改善肝臟脂肪滴沉積,其機(jī)制可能與改善肝臟脂代謝紊亂和對抗糖尿病引起的肝損傷有關(guān),但具體機(jī)制仍需要進(jìn)一步研究。
[參考文獻(xiàn)]
[1] Tu S,Shao A,Ren L,et al. Angiogenesis effect of Astragalus polysaccharide combined with endothelial progenitor cells therapy in diabetic male rat following experimental hind limb ischemia[J]. Chin Med J(Engl),2014, 127(11):2121-2128.
[2] Zhao L,Wu H,Zhao A,et al. The in vivo and in vitro study of polysaccharides from a two-herb formula on ulcerative colitis and potential mechanism of action[J]. Journal of Ethnopharmacology,2014,153(1):151-159.endprint
[3] Kai Z,Michela P,Antonio P,et al. Biological active ingredients of traditional Chinese herb Astragalus membranaceus on treatment of diabetes: a systematic review[J].Mini Reviews in Medicinal Chemistry,2015,15(4):315-329.
[4] Guariguata L,Whiting DR,Hambleton I,et al. Global estimates of diabetes prevalence for 2013 and projections for 2035[J]. Diabetes Research and Clinical Practice,2014, 103(2):137-149.
[5] Asante E. Interventions to promote treatment adherence in type 2 diabetes mellitus[J]. British Journal of Community Nursing,2013,18(6):267-274.
[6] Agarwal AA,Jadhav PR,Deshmukh YA. Prescribing pattern and efficacy of anti-diabetic drugs in maintaining optimal glycemic levels in diabetic patients[J]. Journal of Basic and Clinical Pharmacy,2014,5(3): 79.
[7] Yang W,Lu J,Weng J,et al. Prevalence of diabetes among men and women in China[J]. New England Journal of Medicine,2010,362(12):1090-1101.
[8] Al-Awar A,Kupai K,Veszelka M,et al. Experimental diabetes mellitus in different animal models[J]. Journal of Diabetes Research,2016.
[9] FDA. Guidance for industry diabetes mellitus: developing drugs and therapeutic biologics for treatment and prevention [EB/OL]. 2008[2014-09-05]. http://www. fda.gov/downloads/Drugs/Guidances/ ucm071624.pdf.
[10] Peterson RG,Shaw WN,Neel MA,et al. Zucker diabetic fatty rat as a model for non-insulin-dependent diabetes mellitus[J]. ILAR Journal,1990,32(3):16-19.
[11] 段煉,李會(huì)軍,聞曉東,等. 黃芪治療糖尿病研究進(jìn)展[J].中國新藥雜志,2013,22(7):776-781.
[12] Yao XM,Liu YJ,Wang YM,et al. Astragaloside IV prevents high glucose-induced podocyte apoptosis via downregulation of TRPC6[J]. Molecular Medicine Reports,2016,13(6):5149-5156.
[13] 王光浩,張敬芳,楊雪琴. 黃芪注射液治療糖尿病腎病的實(shí)驗(yàn)研究[J]. 微循環(huán)學(xué)雜志,2007,17(1): 20-21.
[14] Xie JH,Jin ML,Morris GA,et al. Advances on bioactive polysaccharides from medicinal plants[J]. Critical Reviews in Food Science and Nutrition,2016,56(sup1):S60-S84.
[15] Chaumontet C,Even PC,Schwarz J,et al. High dietary protein decreases fat deposition induced by high-fat and high-sucrose diet in rats[J]. British Journal of Nutrition,2015,114(8):1132-1142.
[16] Korolczuk A. Progranulin,a new adipokine at the crossroads of metabolic syndrome,diabetes,dyslipidemia and hypertension[J]. Current Pharmaceutical Design,2017,23(10): 1533-1539.
[17] Tao R,Xiong X,Harris RA,et al. Genetic inactivation of pyruvate dehydrogenase kinases improves hepatic insulin resistance induced diabetes[J]. PLoS One,2013,8(8): e71997.
[18] Guo R,Nair S,Zhang Y,et al. Adiponectin deficiency rescues high-fat diet-induced hepatic injury,apoptosis and autophagy loss despite persistent steatosis[J]. International Journal of Obesity,2017,14(9):1403.
[19] Jiang W,Li D,Jiang T,et al. Protective effects of Chaihu Shugan San on nonalcoholic fatty liver disease in rats with insulin resistance[J]. Chinese Journal of Integrative medicine,2016,5(10):1-8.
[20] Van Beek JH,De Moor MH,De Geus EJ,et al. The genetic architecture of liver enzyme levels:GGT,ALT and AST[J]. Behavior Genetics,2013,43(4):329-339.
(收稿日期:2017-06-04)endprint