银杏黄酮对糖尿病肾病大鼠的肾保护作用及机制探讨

目的 观察银杏黄酮对糖尿病肾病(DN)大鼠的肾保护作用,并探讨其机制.方法 将40只大鼠随机分为4组,每组各10只.A组不处理,B、C、D组左下腹腔注射STZ 60 mg/kg制备糖尿病模型,B、C组分别给予非酶糖化终末产物(AGEs)生成抑制剂氨基胍100 mg/(kg·d)、银杏黄酮150 mg/(kg·d)灌胃,A、D组给予同体积生理盐水.分别于治疗第4、8、12、16周测定24 h尿白蛋白,治疗前及治疗后16周测定体质量及空腹血糖;治疗16周后处死大鼠,取部分肾皮质进行电镜观察并测定AGEs.结果 治疗16周,B、C、D组体质量明显低于A组(P均＜0.01),B、C组血糖与治疗前相比无明显差异,B、C、D组间体质量无显著差异;A、B、C、D组肾皮质AGEs含量分别为(118.34±21.51)、(139.18±36.41)、(137.23±36.24)、(251.09±51.74) AUF/mg,B、C、D组AGEs含量显著高于A组(P均＜0.01),B、C组AGEs含量明显低于D组(P均＜0.01),B、C组间无显著差异;治疗16周后,B、C组24 h尿蛋白定量均低于D组(P均＜0.01);与A组比较,B、C、D组肾小球基底膜厚度增加、系膜间隙面积增大(P均＜0.05),B、C组较D组厚度及面积均减小(P均＜0.05).结论 银杏黄酮可降低DN大鼠尿蛋白、减轻肾组织损伤,该作用与其抑制非酶糖化作用有关.     

氨基胍抑制氨基脲敏感性胺氧化酶活性对糖尿病大鼠血管并发症的预防作用

目的探讨氨基胍在体内外对氨基脲敏感性胺氧化酶（SSAO）的抑制效果及对糖尿病大鼠血管并发症的预防作用。方法取雄性SD大鼠主动脉匀浆作为SSAO酶样来源,体外应用苯甲胺作为SSAO催化底物,在酶促反应体系中加入一系列浓度的氨基胍,采用高效液相色谱法检测SSAO活性;取雄性SD大鼠35只,随机分为正常对照组、糖尿病模型组（DM组）和氨基胍干预组（DM＋氨基胍组）,采用单次腹腔注射链脲佐菌素建立糖尿病模型,DM＋氨基胍组腹腔注射氨基胍25mg/（kg·d）。8周末检测大鼠血浆SSAO活性、甲胺、甲醛、内皮素1（ET-1）、一氧化氮（NO）浓度,同时检测主动脉组织SSAO活性,HE染色及透射电镜分别观察大鼠胸主动脉、肾组织形态学改变。结果氨基胍对大鼠主动脉组织SSAO具有较强的抑制作用,IC₅₀为12.47μmol/L;DM组SSAO活性、ET-1浓度高于正常对照组,血浆NO浓度低于正常对照组（P<0.01）;氨基胍明显抑制糖尿病大鼠SSAO活性,降低ET-1浓度,升高甲胺、NO浓度（P<0.01）;DM＋氨基胍组主动脉、肾组织病理改变较DM组明显减轻。结论氨基胍可有效抑制SSAO活性,可通过抑制SSAO氧化脱氨作用预防糖尿病血管并发症。     

壳聚糖对大鼠动脉粥样硬化的影响及其机制探讨

目的:研究壳聚糖对大鼠动脉粥样硬化斑块及一氧化氮合酶(NOS)的影响。方法:40只Wistar大鼠均分为:A组(正常对照组);B组:饲以高脂饲料(不含维生素D3);C组:一次性给予大鼠维生素D3(30万U/kg体重)肌肉注射,以球囊损伤主动脉内皮和饲以含维生素D3(1.25×106U/kg)的高脂饲料;D组在C组的基础上饲料中加入5%壳聚糖。90 d后检测主动脉动脉粥样硬化斑块形成及NOS的活性。结果:(1)90 d后C组大鼠胸主动脉形成了明显的动脉粥样硬化斑块,而仅饲以高脂饲料的大鼠胸主动脉结构未见改变,D组大鼠胸主动脉未形成动脉粥样硬化斑块;(2)血管中内皮型一氧化合酶(eNOS)后三组较A组均活性下降(P<0.01),而三者之间无统计学差异;(3)诱导型一氧化氮合成酶(iNOS):B组较A组无差异,而C组较A、B两组表达和活性均显著增加(P<0.05~<0.01),较之C组,D组的水平下降(P<0.01),但仍高于A、B组(P<0.01);(4)较之A组,B、C组的TC、TG、LDL-C水平上升(P<0.05~<0.01),D组的较C组下降(P<0.05~<0.01);B、C组的HDL-C水平较A组明显下降(P<0.01)。结论:壳聚糖可通过抑制胆固醇、甘油三酯等的吸收而发挥抗动脉粥样硬化作用,并通过对血脂的作用而间接发挥对NOS的影响。     

SARS冠状病毒N蛋白致大鼠肺部炎症及糖皮质激素对其的作用

目的探讨严重急性呼吸综合征(SARS)冠状病毒N蛋白所致大鼠肺部炎症反应及糖皮质激素(以下简称激素)对其的调节作用。方法24只SD大鼠随机分为4组,每组6只;A组大鼠气管内滴入无菌生理盐水0.2ml,B组(6h)、C组(24h)大鼠气管内滴入SARS病毒N蛋白溶液0.2ml,D组大鼠气管内滴入SARS病毒N蛋白溶液0.2ml的同时腹腔内注射10mg/kg地塞米松。测4组大鼠外周血、支气管肺泡灌洗液(BALF)中WBC总数及分类;测4组大鼠肺组织湿/干(W/D)比值;观察4组大鼠肺组织病理学变化;ELISA测4组大鼠血清及BALF中IL6、IL10、转化生长因子(TGF)β1水平。结果(1)外周血淋巴细胞比例C组较A组低(P<0.05),D组较A、C组均低(P值均小于0.01);D组WBC总数较A、C组均低(P<0.01)。BALF中WBC总数C组较A组高(P<0.05),D组较C组低(P<0.05);B、C组BALF中肺泡巨噬细胞占98%～99%。(2)肺脏W/D比值B、C组较A组高(P<0.05),D组较C组低(P<0.01)。(3)肺组织病理学变化:B、C组大鼠肺泡间隔明显增宽,有较多的炎性细胞渗出,包括中性粒细胞、淋巴细胞、单核细胞、成纤维细胞等,血管充血、淤血,有的支气管腔内有炎性细胞渗出,C组变化较B组无明显加重;D组大鼠肺组织炎性反应较B、C组减轻,肺泡间隔变薄,炎性细胞渗出减少。(4)血清及BALF中IL6、IL10、TGFβ1水平B组较A组高(P<0.01),C组进一步升高(P<0.01),D组较C组低(P<0.01)。结论SARS冠状病毒N蛋白具有致病性,能够引起大鼠肺部炎症反应和(或)急性肺损伤,肺损伤与促炎性细胞因子、抗炎性细胞因子的升高及失衡有关;激素可有效地减轻SARS冠状病毒N蛋白所致的肺部炎症反应。     

叶酸对2型糖尿病大鼠胸主动脉内皮功能的影响

目的探讨长期补充叶酸对2型糖尿病大鼠胸主动脉内皮功能的影响及其作用机制。方法将2型糖尿病大鼠37只分为模型组(12只)、小剂量叶酸组(12只)和大剂量叶酸组(13只),另11只正常大鼠为正常对照组,叶酸干预11周后,剪尾采血分别检测血清一氧化氮、超氧化物歧化酶及丙二醛水平,并取胸主动脉制备主动脉环进行离体血管环反应性测定。结果模型组大鼠血清一氧化氮和超氧化物歧化酶水平明显低于正常对照组(P<0.01),而血清丙二醛水平明显高于正常对照组(P<0.01);补充叶酸11周后,小剂量叶酸组及大剂量叶酸组血清一氧化氮及超氧化物歧化酶水平均较模型组有明显增高(P<0.05或P<0.01),而血清丙二醛水平较模型组明显降低(P<0.01)。在每一个乙酰胆碱累积浓度下,模型组大鼠胸主动脉环的舒张度均较正常对照组明显减低(P<0.05或P<0.01),而小剂量叶酸组和大剂量叶酸组大鼠胸主动脉环的舒张度则均较模型组明显增高(P<0.05或P<0.01),小剂量叶酸组大鼠胸主动脉环的舒张度与大剂量叶酸组相比差异无显著性。结论长期补充叶酸对2型糖尿病大鼠血管内皮功能损伤具有明显预防作用,叶酸可能通过增加机体一氧化氮合成从而提高血清一氧化氮活性和提高机体抗氧化能力来预防2型糖尿病大鼠血管内皮功能损伤的发生。     

人参皂甙Rg3对高龄大鼠血管结构与功能的影响

目的:研究人参皂甙Rg3对高龄大鼠血管壁结构和血管收缩、舒张功能的影响。方法:40只12月龄的SD大鼠随机分为观察组(B组,10只)和治疗组(C组,30只)。治疗组按给药剂量的不同被随机分为C1组、C2组、C3组,分别给予人参皂甙Rg3 5、10、20mg·kg-1·d-1灌胃治疗;B组给予安慰剂治疗。两组均普通饮食喂养,20月龄时,在无菌条件下取大鼠的胸主动脉条备检。10只3月龄的SD大鼠为青年组(A组)阴性对照组,同样方法取材备检。采用HE染色和电镜观察胸主动脉结构,用离体胸主动脉血管环灌流实验检测血管的收缩和舒张功能。结果:A组大鼠血管壁形态正常。B组大鼠血管平滑肌细胞增殖、管腔狭窄、基质明显增生。B组血管收缩和舒张功能均较A组下降(P0.05)。C3组的血管收缩和舒张功能较B明显改善(P0.05)。结论:高龄大鼠血管壁发生明显的血管老化病理和病理生理变化,表现为平滑肌细胞增殖、管腔狭窄、基质增生、胞质脂褐素沉积、血管收缩和舒张功能下降。人参皂甙Rg3长期服用能够显著地抑制高龄大鼠血管中层平滑肌细胞增殖,减轻基质增生,抑制血管舒缩功能的降低,有潜在的抗血管老化作用。     

糖尿病视网膜病变患者玻璃体中AGE、VEGF的表达及意义

目的 探讨糖尿病视网膜病变玻璃体中糖基化终产物(AGEs)和血管内皮生长因子(VEGF)水平与糖尿病视网膜病变的关系.方法 采用ELISA法测定41例糖尿病视网膜病变患者(A组)玻璃体中的AGEs和VEGF,并与28例非糖尿病(B组)进行对照;A组选20例和B组选18例,用黄嘌呤氧化酶法测定玻璃体内超氧化物歧化酶(SOD),用改良Witko-Sarsat法测定血清晚期氧化蛋白产物(AOPP).结果 A组玻璃体内AGEs 和 VEGF水平明显高于B组(P＜0.01),AGEs与VEGF呈正相关(r=0.64, P＜0.001),A组玻璃体内的抗氧化能力较B组明显降低(P＜0.01).结论 糖尿病视网膜病变的发生与其玻璃体内AGEs和抗氧化能力的降低有关,其作用是通过VEGF而产生的 ;玻璃体内AGEs 和 VEGF水平越高,其抗氧化能力越低.     

激动κ阿片受体对糖尿病大鼠血管舒缩功能及结构的影响

目的研究激动κ阿片受体(KOR)对糖尿病大鼠肠系膜小动脉血管舒缩功能及主动脉结构的影响,探讨其作用机制。方法选取雄性SD大鼠40只,分为对照组(16只)和模型组(24只)。其中,对照组分为正常组和正常+U50,488H组(U50,488H 1组),每组8只;模型组分为糖尿病组、糖尿病+U50,488H组(U50,488H 2组)和糖尿病+nor-BNI组(nor-BNI组),每组8只。采用体外血管环灌流技术检测肠系膜小动脉血管舒缩功能;Westernblot法检测小动脉血管组织内皮型一氧化氮合酶(eNOS)、NF-κB及KOR表达水平;光镜HE染色观察主动脉结构变化。结果与正常组比较,糖尿病组对KCl和去甲肾上腺素引起的收缩反应明显增强(P0.05),对乙酰胆碱引起的舒张反应明显减弱(P0.05),对硝普钠引起的舒张反应无明显变化;eNOS表达减少,而NF-κB及KOR表达增加(P0.01)。U50,488H处理后,eNOS及KOR表达增加而NF-κB表达减少;nor-BNI处理后,eNOS及KOR表达减少而NF-κB表达增加(P0.01)。结论激动KOR可改善糖尿病大鼠肠系膜小动脉血管舒缩功能和主动脉结构,机制可能与通过增加eNOS表达改善内皮功能和通过抑制NF-κB表达降低炎症水平有关。     

橙皮苷对STZ糖尿病大鼠肾脏功能和形态的影响

观察橙皮苷对链脲佐菌素导致的糖尿病大鼠肾脏功能和形态的影响,并与氨基胍进行比较。结果表明:（1）两治疗组大鼠尿蛋白排泄量显著低于对照组P<0.05）;（2）两治疗组肾组织AGEs和LPO含量显著低于对照组（P<0.01,P<0.05）:（3）治疗组肾小球系膜增生和基底膜增厚明显减轻。提示橙皮苷在抑制蛋白非酶糖基化、预防糖尿病肾脏并发症方面具有与氨基胍相似的作用。     

奥美沙坦酯及坎地沙坦酯对动脉粥样硬化大鼠炎症反应的影响

目的观察比较奥美沙坦酯、坎地沙坦酯对动脉粥样硬化(AS)大鼠炎症反应的影响。方法 40只雄性Wistar大鼠随机分为4组,即正常组(A组)、高脂组(B组)、坎地沙坦酯组(C组)、奥美沙坦酯组(D组),每组10只。B组、C组及D组喂以高脂饲料复制动脉粥样硬化模型,C组、D组同时以坎地沙坦酯及奥美沙坦酯干预,共饲养8周。于实验开始时及8周末测定大鼠体质量、酶联免疫吸附试验法(ELISA)测定血清单核细胞趋化蛋白-1(MCP-1)及可溶性P选择素(sP-选择素)含量;8周末时,大鼠麻醉后开胸并迅速分离胸主动脉-腹主动脉,用作RT-PCR半定量测定主动脉组织中CD40及CD40L表达,用紫外检测仪照相并观察,计算主动脉组织中CD40及CD40L的相对表达量,比较各组间主动脉CD40及CD40L表达不同。结果 0周时,各组大鼠体质量、血脂水平、血清MCP-1及sP-选择素无统计学意义(P>0.05);8周末,B组、C组、D组体质量、血脂含量、血清MCP-1及sP-选择素较A组明显升高(P<0.01),与B组比较,C组、D组血清MCP-1及sP-选择素含量明显降低(P<0.01),且与C组比较,D组血清MCP-1及sP-...     

糖尿病大鼠主动脉糖化终产物的免疫组化研究

目的　研究糖尿病时主动脉壁非酶糖化的程度以及非酶糖化机制在糖尿病血管重建和慢性并发症发生发展中的作用。方法　应用抗糖化终产物（ＡＧＥｓ） 多克隆抗体,对糖尿病大鼠和氨基胍治疗后的糖尿病大鼠进行主动脉壁ＡＧＥｓ 的免疫组化研究,计算机图像处理系统定量分析。结果糖尿病时主动脉壁中膜ＡＧＥｓ 的相对面积呈进行性增加,４ 周时其相对面积就显著大于对照组（ Ｐ＜０．０１）,氨基胍治疗４ 周后主动脉壁中膜ＡＧＥｓ 的相对面积较糖尿病组显著降低（ Ｐ＜ ０．０５）,治疗２４周后降低更为明显（Ｐ＜ ０．０１）。结论　主动脉壁ＡＧＥｓ 的免疫组化定量研究能更直观地反映血管组织非酶糖化的程度,非酶糖化是引起血管重建的重要机制之一。     

Attenuation of hypertension development by aminoguanidine in spontaneously hypertensive rats: role of methylglyoxal

BACKGROUND: Methylglyoxal (MG), a metabolite of glucose, and MG-induced advanced glycation endproducts (AGEs) are causatively associated with vascular complications of diabetes mellitus. We have previously reported elevated levels of MG and MG-induced AGEs in spontaneously hypertensive rats (SHR). The purpose of this study was to investigate the causative role of MG and MG-induced AGEs in the pathogenesis of hypertension in SHR. METHODS: Young SHR were treated with an AGE inhibitor, aminoguanidine, for 9 weeks. HPLC was used to determine plasma and aortic MG and reduced glutathione levels. The MG-induced AGEs, N epsilon-carboxyethyl-lysine (CEL) and argpyramidine, in the aorta were determined by immunohistochemistry. Vascular relaxation of small mesenteric arteries was measured using myograph. RESULTS: Chronic treatment with aminoguanidine attenuated age-dependent blood pressure (BP) increase in SHR. Plasma and aortic MG levels, and aortic levels of MG-induced AGEs, were significantly reduced after aminoguanidine treatment, which were comparable to those from age-matched Wistar Kyoto rats. Free radical level was significantly lowered, whereas reduced glutathione level was significantly increased by aminoguanidine treatment in the aortic tissues from SHR. Moreover, aminoguanidine therapy prevented the morphologic damage of vascular tissues in SHR and restored the endothelium-dependent relaxation to acetylcholine. Chronic aminoguanidine treatment also increased aortic endothelial nitric oxide synthase expression and reduced inducible nitric oxide synthase expression. CONCLUSIONS: The MG and MG-induced AGEs contribute to the pathogenesis of hypertension by altering the redox balance, causing vascular eutrophic inward remodeling, and inducing endothelial dysfunction in SHR.     

Maternal and postnatal vitamin D ingestion influences rat aortic structure,function and elastin content

OBJECTIVES: Subtle impairment of fetal nutrition appears to predict hypertension and atherosclerosis in adults. It has been hypothesised that impaired aortic elastogenesis is the initiating step in adult hypertension and aortic aneurysms. Vitamin D has been shown to inhibit elastin synthesis by cultured smooth muscle cells. Here we have investigated, in rats, the hypothesis that increased exposure to vitamin D during gestation and in the postnatal period alters aortic elastin content and aortic function. METHODS: Nine breeding pairs of Sprague-Dawley rats were allocated to one of three diets containing 3000 (control group), 6000 (low dose) or 12,000 (high dose) IU/kg vitamin D during pregnancy and lactation. Male pups were continued on the same diet until 6 weeks of age. Aortic elastin content was assessed by measuring desmosine+isodesmosine content using capillary zone electrophoresis. Transverse aortic sections were used for quantification of elastic lamellae and morphometric analysis. The contractility of aortic rings was assessed in an organ bath preparation. RESULTS: The desmosine+isodesmosine content of the abdominal aorta of 6-week-old male pups, was 14.1, 10.0 and 10.1 nmol/mg dry weight in the control (n=20), low- (n=23) and high-dose (n=15) groups, respectively (P=0.007). The median number of elastic lamellae of the distal thoracic aorta was 8.25, 7.13 and 6.88 in the control, low-dose and high-dose groups, respectively (P<0.001). There were no significant differences in aortic cross-sectional areas or media:adventitia ratios. The mean peak tension of aortic rings, in response to phenylephrine, was 1.3 g, 1.12 g and 0.87 g in the control, low- and high-dose groups respectively (P=0.002). CONCLUSION: In rats, exposure to increased amounts of vitamin D during gestation and early life results in a reduction of aortic elastin content, number of elastic lamellae in the aorta and force generation in aortic rings.     

肾血管性高血压大鼠血管内皮细胞功能的变化

目的观察肾血管性高血压(RVH)大鼠血管内皮细胞功能的变化并探讨其机制。方法体重为160~180g健康雄性Wistar大鼠随机分成2组高血压模型(RVH)组及对照(C)组。术后4周,用颈动脉直接插管法测定大鼠血压,应用生物测定法观察大鼠离体主动脉舒缩反应及美蓝(MB)、L-NAME、硝普钠(SNP)、左旋精氨酸(L-Arg)对其的影响。结果RVH大鼠离体胸主动脉环对苯肾上腺素(PHE)引起的收缩反应比对照组明显增高,去除内皮后可消除两组差异。鸟苷酸环化酶抑制剂美蓝及NO合成酶抑制剂L-NAME可使对照组收缩反应增加较RVH组明显。RVH大鼠胸主动脉环由乙酰胆碱(Ach)引起的内皮依赖性舒张反应较对照组明显减弱,而对非内皮依赖性松弛剂硝普钠(SNP)的舒张反应两组间无显著差异。NO合成底物L-Arg能显著提高RVH大鼠内皮依赖性舒张反应。结论肾血管性高血压血管内皮依赖的收缩反应增强,舒张反应减弱。其机制是血管内皮产生和释放EDRF(NO)功能受损和(或)EDRF作用减弱,合成NO的底物L-Arg不足。     

Exogenous advanced glycosylation end products induce complex vascular dysfunction in normal animals: a model for diabetic and aging complications.

Advanced glycosylation end products (AGEs) have been implicated in many of the complications of diabetes and normal aging. Markedly elevated vascular tissue and circulating AGEs were linked recently to the accelerated vasculopathy of end-stage diabetic renal disease. To determine the pathogenic role of AGEs in vivo, AGE-modified albumin was administered to healthy nondiabetic rats and rabbits alone or in combination with the AGE-crosslink inhibitor aminoguanidine. Within 2-4 weeks of AGE treatment, the AGE content of aortic tissue samples rose to six times the amount found in controls (P < 0.001). Cotreatment with aminoguanidine limited tissue AGE accumulation to levels two times that of control. AGE administration was associated with a significant increase in vascular permeability, as assessed by 125I label tracer methods. This alteration was absent in animals that received aminoguanidine in addition to AGE. Significant mononuclear cell migratory activity was observed in subendothelial and periarteriolar spaces in various tissues from AGE-treated rats compared to normal cellularity noted in tissues from animals treated with aminoguanidine. Blood pressure studies of AGE-treated rats and rabbits revealed markedly defective vasodilatory responses to acetylcholine and nitroglycerin compared to controls (P < 0.001), consistent with marked NO. inactivation; aminoguanidine treatment significantly prevented this defect. These in vivo data demonstrate directly that AGEs, independent of metabolic or genetic factors, can induce complex vascular alterations resembling those seen in diabetes or aging. AGE administration represents an animal model system for the study of diabetic and aging complications as well as for assessing the efficacy of newly emerging therapies aimed at inhibiting advanced glycosylation.     

Impairment of endothelium dependent responses in a rat model of chronic heart failure: effects of an exercise training protocol.

OBJECTIVE: The aim was to document the response of aortic rings from a rat model of heart failure to endothelium dependent and endothelium independent vasodilating agents. The effects of an exercise training schedule upon these responses was studied. METHODS: Heart failure was produced in one group of female Wistar rats by coronary artery occlusion, and sham operations were performed in a matched group. The rats were allowed to recover for six weeks, following which half the rats with heart failure were started on a treadmill exercise schedule for a further six weeks. After this time the rats were killed, and rings of aorta were studied in an organ bath to measure the response to both endothelium dependent and endothelium independent vasoactive agents. RESULTS: The presence of heart failure was confirmed in both the non-trained (NT, n = 5) and trained rats (TR, n = 5), but not in the sham operated animals (SH, n = 6). The constrictor response to prostaglandin F2 alpha was similar in aortic rings from all the animals. The relaxation response to the endothelium dependent vasodilator acetylcholine (10(-7) and 10(-6) M) was impaired in the rats with heart failure compared to the sham operated animals (10% v 33% with 10(-7) M acetylcholine, p < 0.005). The dilator response in the trained rats was not significantly greater than in the non-trained rats (TR 35% v NT 24% with 10(-6) M acetylcholine). There was no difference in the response to sodium nitroprusside (10(-7) and 10(-6) M) between the three groups. CONCLUSIONS: Chronic heart failure impairs the response of aortic rings to the endothelium dependent vasodilator acetylcholine in a rat model of heart failure. The response to sodium nitroprusside, an endothelium independent relaxing agent, is not impaired by heart failure. These findings may help to explain the raised systemic vascular resistance and the failure of vasodilatation in skeletal muscle vasculature which limits exercise capacity in subjects with heart failure.     

Exendin-4对2型糖尿病大鼠主动脉内皮核因子-κB和细胞间黏附分子-1表达的影响

目的探讨Exendin-4对2型糖尿病大鼠主动脉内皮NF-κB p65以及细胞间黏附分子-1(ICAM-1)表达的影响。方法选择40只雄性SD大鼠,6只喂基础饲料为正常对照组(NC组),另34只喂高脂饲料4周后,一次性腹腔注射链脲佐菌素,建立2型糖尿病大鼠模型,维持2周,24只大鼠造模成功,并分为糖尿病组(DM组)、Exendin-4低剂量治疗组(GL组)、中剂量治疗组(GM组)、高剂量治疗组(GH组),每组6只,给予不同剂量Exendin-4腹腔注射治疗6周。心脏采血检测丙二醛(MDA)、超氧化物歧化酶(SOD)、总抗氧化能力(T-AOC)水平。之后分离胸主动脉,免疫组织化学方法观察主动脉内皮NF-κB p65和TCAM-1的表达。结果与NC组比较,DM组MDA升高,SOD和T-AOC降低(P<0.05)。与DM组比较,GH组MDA降低,SOD、T-AOC升高;且NF-κB p65表达明显降低(P<0.05)。与GL组比较,GM组、GH组ICAM-1表达明显降低,差异均有统计学意义(P<0.05)。结论 Exendin-4具有血管内皮保护作用,其机制与抗氧化、抑制血管内皮NF-κB p65、ICAM-1的活化有关。     

Role of endothelium-derived prostanoid in angiotensin-induced vasoconstriction

To test the hypothesis that prostanoids contribute to angiotensin II-induced vascular contraction, we compared the effect of angiotensin II on isometric tension development by rings of descending thoracic aorta bathed in Krebs' bicarbonate buffer with and without indomethacin (10 microM) to inhibit cyclooxygenase, CGS13080 (10 microM) to inhibit thromboxane A2 synthesis, or SQ29548 (1 microM) to block thromboxane A2/prostaglandin endoperoxide receptors. The comparisons were made in rings of aorta taken from normotensive rats and from rats with aortic coarctation-induced hypertension at 12 days and 90-113 days after coarctation. These rings released thromboxane B2, which was found to be endothelium dependent, increased in hypertensive rats, and stimulated by angiotensin II (10(-6) M) in normotensive rats and in hypertensive rats at 12 days after coarctation. The angiotensin II (10(-6) to 10(-5)M)-induced contraction of aortic rings was increased by about 30% at 12 days after coarctation and decreased at 90-113 days after coarctation. Removal of the endothelium increased the contractile effect of angiotensin II (10(-6) M) in aortic rings of normotensive rats and hypertensive rats at 90-113 days after coarctation but decreased the effect in aortic rings of hypertensive rats at 12 days after coarctation. In rats at 12 days after coarctation, the angiotensin II (10(-6) M)-induced contraction of aortic rings with endothelium was attenuated by indomethacin and SQ29548 but not by CGS13080. These data suggest that a prostanoid-mediated and endothelium-dependent mechanism of vasoconstriction contributes to the constrictor effect of angiotensin II in aortic rings of rats in the early phase of aortic coarctation-induced hypertension.