三七总皂苷联合氨基胍治疗对糖尿病大鼠肾脏氧化损伤的影响

目的 研究三七总皂苷联合氨基胍治疗对糖尿病大鼠肾组织氧化损伤的影响及其机制.方法 清洁级健康雄性SD大鼠48只,腹腔注射链脲佐菌素,建立糖尿病大鼠模型,按数字表法随机分为糖尿病模型组(n=12)、三七总皂苷治疗组(n=12)、氨基胍治疗组(n=12)和三七总皂苷+氨基胍联合治疗组(n=12);另设正常对照组(n=12).第4、8周应用比色法测定血清及肾皮质超氧化物歧化酶及丙二醛含量,采用荧光光谱法测定血清和肾皮质晚期糖基化终产物含量,行肾组织PAS染色并测定肾小球平均截面积,计算肾小球平均体积.采用单因素方差分析进行组间比较.结果 三七总皂苷+氨基胍联合治疗组血清及肾皮质晚期糖基化终产物(F=36.017,P<0.01;F=8.213,P<0.01)、丙二醛(F=8.683,P<0.01;F=14.615,P<0.01)、内生肌酐清除率(F=7.233,P<0.01)、肾小球平均截面积(F=24.317,P<0.01)、肾小球平均体积(F=26.145,P<0.01)、尿蛋白量(F=17.108,P<0.05)、肾脏重量(F=5.182,P<0.05)、肾脏肥大指数(F=50.169,P<0.01)低于糖尿病模型组,血清及肾皮质超氧化物歧化酶(F值分别为6.260、7.666,均P<0.01)、体重(F=10.449,P<0.05)高于糖尿病模型组.三七总皂苷+氨基胍联合治疗组血清丙二醛低于氨基胍治疗组(F=8.683,P<0.05),肾皮质丙二醛低于氨基胍治疗组和三七总皂苷治疗组(F=14.615,P<0.05),血清晚期糖基化终产物低于氨基胍治疗组和三七总皂苷治疗组(F=36.017,P<0.01或<0.05),肾皮质晚期糖基化终产物低于氨基胍治疗组和三七总皂苷治疗组(F=8.213,P<0.05).8周末时,三七总皂苷+氨基胍联合治疗组肾小球平均截面积、肾小球平均体积均低于三七总皂苷治疗组(F值分别为24.317、26.145,均P<0.05)和氨基胍治疗组(F值分别为24.317、26.145,均P<0.05).结论 三七总皂苷+氨基胍联合治疗可通过减轻肾组织氧化应激反应、减少肾组织晚期糖基化终产物的生成与蓄积对糖尿病大鼠肾脏起到保护作?     

氨基胍对2型糖尿病模型大鼠行为学改变和树突棘素表达变化的影响

目的观察氨基胍对2型糖尿病(T2DM)大鼠行为学改变和树突棘素表达变化的影响。方法将大鼠随机分为对照组、模型组、氨基胍组。模型组及氨基胍组建立T2DM大鼠模型,造模成功后,氨基胍组给予氨基胍溶液灌胃(剂量为150 mg·kg~(-1)·min~(-1)),模型组给予等量生理盐水灌胃,对照组不予灌胃处理。分别于6、12、16 w应用Morris水迷宫对各组大鼠进行行为学评价;并于12、16 w采用免疫组化法检测各组大鼠海马区树突棘素的表达变化。结果与对照组相比,12、16 w模型组潜伏期明显延长(P<0.05);树突棘素表达显著减少(P<0.05),并随疾程进展呈递减趋势。与模型组比较,同一时间点氨基胍组大鼠潜伏期明显缩短(P<0.05),树突棘素表达显著增多(P<0.05或P<0.01),并随着治疗进程呈持续增多趋势。结论氨基胍可促进T2DM大鼠脑树突棘素的表达增加,而发挥脑保护作用,改善T2DM引起的认知功能障碍。     

糖基化终产物对糖尿病大鼠肾脏血管紧张素转换酶2表达的调节

目的 观察糖基化终产物(AGEs)对糖尿病大鼠肾脏血管紧张素转换酶2(ACE2)表达的调节和意义.方法 诱导糖尿病模型后,立即给予干预组糖尿病大鼠氨基胍.第12周末检测尿白蛋白排泄率(UAER)、肾脏系膜外基质增生(MME),测定肾内ACE2、ACE蛋白表达,计算ACE2/ACE比值,并检测肾脏ACE2mRNA水平.结果 与糖尿病对照组相比,氨基胍干预组UAER及MME降低(P< 0.05),肾脏ACE2表达及ACE2/ACE比值增加(P< 0.05).结论 AGEs可下调糖尿病大鼠肾脏ACE2表达,减少ACE2/ACE比值,可能是导致糖尿病肾病的重要原因之一.     

橙皮苷与氨基胍对STZ－糖尿病大鼠主动脉胶原非酶糖化作用的比较

本文观察了天然黄酮类化合物──橙皮苷对ＳＴＺ－糖尿病大鼠主动脉胶原非酶糖基化作用的影响，并与氨基肌进行了比较。结果表明：用橙皮苷及氨基肌治疗１２０天后，糖尿病鼠动脉胶原ＡＧＥｓ含量明显降低（Ｐ＜０．０１），而血糖、体重无明显差别。提示橙皮苷对糖尿病大鼠蛋白非酶糖基化作用与氨基胍相似。     

丝胶对糖尿病大鼠肾脏转化生长因子-β_1表达的影响

目的观察丝胶对糖尿病大鼠肾脏转化生长因子-β1(TGF-β1)表达的影响。方法 48只雄性SD大鼠随机分为正常对照组、糖尿病模型组、丝胶治疗组和阳性对照组,每组12只。链脲佐菌素腹腔注射建立2型糖尿病大鼠模型,丝胶治疗组大鼠给予丝胶(2.4 g/kg)灌胃、阳性对照组大鼠给予二甲双胍(55.33 mg/kg)灌胃。分别检测各组大鼠的血肌酐和尿素氮,SP免疫组织化学染色法观察大鼠肾脏TGF-β1的表达。结果糖尿病模型组大鼠的血尿素氮和肌酐明显高于正常对照组大鼠(P<0.01),丝胶治疗组、阳性对照组大鼠的血尿素氮和肌酐明显低于糖尿病模型组大鼠(P<0.01,P<0.05)。TGF-β1蛋白免疫阳性产物呈棕黄色细腻颗粒状,位于肾小囊壁层上皮细胞、足细胞和球内系膜细胞的胞浆。糖尿病模型组大鼠肾脏TGF-β1蛋白的表达明显高于正常对照组大鼠(P<0.01);丝胶治疗组、阳性对照组大鼠肾脏TGF-β1蛋白的表达明显低于糖尿病模型组大鼠(P<0.01)。结论丝胶可通过下调糖尿病大鼠肾脏TGF-β1的表达减轻肾脏肥大和细胞外基质积聚,对糖尿病时肾脏损伤具有一定的保护作用。     

苦荞麦提取物对糖尿病大鼠肾脏糖基化反应的影响及机制

目的观察苦荞麦提取物对链脲佐菌素(STZ)诱导的糖尿病大鼠糖基化反应的影响。方法 STZ诱导建立糖尿病大鼠模型,然后分别给予苦荞麦高、中、低200,100,50 mg·kg-1·d-1剂量和氨基胍100 mg·kg-1·d-1治疗12 w。采用荧光分光光度法测定肾脏组织中糖基化终末产物(AGEs)及硫化巴比妥酸反应物(TBARS)含量;采用免疫印迹法测定肾脏组织中糖基化终末产物受体(RAGE)的蛋白表达水平。结果与正常组比较,模型组肾脏组织中AGEs含量及TBARS含量均显著升高,肾脏组织中RAGE的蛋白表达水平显著升高;与模型组比较,苦荞麦各剂量组及氨基胍组肾脏组织中AGEs含量及TBARS含量均显著降低,以苦荞麦高剂量组下降最明显(P<0.01);苦荞麦各剂量组及氨基胍组肾脏组织中RAGE的蛋白表达水平亦降低,以苦荞麦高剂量组下降明显(P<0.01)。结论苦荞麦能够抑制糖尿病大鼠体内的糖基化反应,并且随着苦荞麦剂量的增加,抑制作用更加明显。     

还原型谷胱甘肽对糖尿病大鼠MDA和TAOC的影响

目的 探讨还原型谷胱甘肽(GSH)对链脲佐菌素(STZ)诱导的糖尿病大鼠丙二醛(MDA)和总抗氧化能力(TAOC)的影响.方法 大鼠分4组:(1) 同龄正常大鼠对照组;(2)糖尿病大鼠对照组;(3)GSH治疗的糖尿病组;(4)皮下注射胰岛素控制血糖在正常范围的糖尿病组(PZI组).2 w后测定血清空腹血糖(FPG)、糖化血清蛋白(GSP)、MDA及TAOC.4 w后测定血清FPG、GSP、MDA 、TAOC以及心脏、肝脏、胰腺、肾脏组织匀浆的MDA和TAOC.结果 GSH治疗组治疗2、4 w后的FPG和GSP与糖尿病对照组比较无统计学差异.2、4 w时GSH治疗组血清MDA显著低于糖尿病对照组(P<0.05,P<0.01),血清TAOC显著高于糖尿病对照组(P<0.05).4 w时GSH治疗组除胰腺外,心、肝、肾组织MDA均低于糖尿病对照组(P<0.05),而TAOC均显著高于糖尿病对照组(P<0.05).结论 GSH能改善STZ诱导的糖尿病大鼠的抗脂质过氧化能力,提高糖尿病大鼠总抗氧化能力.     

中药对糖尿病大鼠肾皮质蛋白质非酶糖化的抑制作用

雄性Wistar大鼠70只,随机平均分为7组,正常对照组,糖尿病对照组氨基胍（100mh／kg／d）治疗组和黄芩苷,葛根素,川芎嗪,水飞蓟素（150mh/kg／d）治疗组,腹腔注射链脲佐菌素（60mg／kg）诱发糖尿病。16周后,处死大鼠,分离肾脏,称重然后进行肾皮质糖基化终末产物（AGEs）测定。结果：治疗前后各组血糖无明显变化。治疗后糖尿病组双肾重量明显高于正常对照（P〈0．01）,5个治疗组双肾重量明显低于糖尿病组（P〈0．01）,各治疗组间无明显差异（P〉0．05）。糖尿病AGEs含量明显高于正常对照（P〈0．01）,5个治疗组AGEs含量明显低于糖尿病组（P〈0．01）,各治疗组间无明显差异（P〉0．05）结论：1．蛋白质非酶糖化生成AGEs参与DN的发生与发展。2．中药对非酶糖化的抑制作用与典型糖化抑制剂氨基胍相似,且价格低、副作用少,值得临床推荐应用。     

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。     

Caspase-3在胰岛素抵抗及其干预组大鼠肾组织中的表达及意义

目的 建立胰岛素抵抗模型并药物干预,观察Caspase-3在肾组织的表达,以探讨其表达与胰岛素抵抗程度的关系.方法 出生当日Wistar大鼠,腹腔注射链脲佐菌素STZ (100 mg/kg)复制胰岛素抵抗模型.设立正常对照组、胰岛素抵抗组、二甲双胍治疗组及川芎嗪+氨基胍干预组(联合治疗组).8周、32周末采血,测空腹血糖、空腹血浆胰岛素,计算胰岛素抵抗指数;32周末取一侧肾组织用4%多聚甲醛固定24 h,石蜡包埋,制作5 μm切片,另一侧肾组织液氮速冻后,-80℃冰箱保存备用.免疫组织化学测定Caspase-3在各组大鼠肾组织中的表达,免疫印迹实验测定肾组织中Caspase-3含量.结果 (1)胰岛素抵抗指数变化,胰岛素抵抗组明显高于对照组(P<0.01),二甲双胍组与联合治疗组均明显低于胰岛素抵抗组(P<0.01),且联合治疗组低于二甲双胍组(P<0.05)(2)Caspase-3变化,胰岛素抵抗组明显高于对照组(P<0.01),二甲双胍组、联合治疗组均明显低于胰岛素抵抗组(P<0.01),且联合治疗组低于二甲双胍组(P<0.05).结论 链脲佐菌素可诱导当日出生的Wistar大鼠产生胰岛素抵抗;该模型肾组织Caspase-3表达增强,且其表达强度与胰岛素抵抗程度正相关;二甲双胍及川芎嗪+氨基胍均有缓解胰岛素抵抗作用,其作用机制与下调Caspase-3表达有关,且川芎嗪+氨基胍的效果优于二甲双胍.     

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。     

Blockade of advanced glycation end-product formation restores ischemia-induced angiogenesis in diabetic mice

We hypothesized that formation of advanced glycation end products (AGEs) associated with diabetes reduces matrix degradation by metalloproteinases (MMPs) and contributes to the impairment of ischemia-induced angiogenesis. Mice were treated or not with streptozotocin (40 mg/kg) and streptozotocin plus aminoguanidine (AGEs formation blocker, 50 mg/kg). After 8 weeks of treatment, hindlimb ischemia was induced by right femoral artery ligature. Plasma AGE levels were strongly elevated in diabetic mice when compared with control mice (579 +/- 21 versus 47 +/- 4 pmol/ml, respectively; P < 0.01). Treatment with aminoguanidine reduced AGE plasma levels when compared with untreated diabetic mice (P < 0.001). After 28 days of ischemia, ischemic/nonischemic leg angiographic score, capillary density, and laser Doppler skin-perfusion ratios were 1.4-, 1.5-, and 1.4-fold decreased in diabetic mice in reference to controls (P < 0.01). Treatment with aminoguanidine completely normalized ischemia-induced angiogenesis in diabetic mice. We next analyzed the role of proteolysis in AGE formation-induced hampered neovascularization process. After 3 days of ischemia, MMP-2 activity and MMP-3 and MMP-13 protein levels were increased in untreated and aminoguanidine-treated diabetic mice when compared with controls (P < 0.05). Despite this activation of the MMP pathway, collagenolysis was decreased in untreated diabetic mice. Conversely, treatment of diabetic mice with aminoguanidine restored collagenolysis toward levels found in control mice. In conclusion, blockade of AGE formation by aminoguanidine normalizes impaired ischemia-induced angiogenesis in diabetic mice. This effect is probably mediated by restoration of matrix degradation processes that are disturbed as a result of AGE accumulation.     

Relative contributions of advanced glycation and nitric oxide synthase inhibition to aminoguanidine-mediated renoprotection in diabetic rats

Summary Advanced glycation end products (AGEs) have previously been shown to be increased in the diabetic kidney. Aminoguanidine, an inhibitor of advanced glycation, has been shown to attenuate the development of AGEs as well as the progression of renal disease in experimental diabetes. However, the precise mechanisms through which aminoguanidine acts remain to be elucidated since it is also able to act as an inhibitor of nitric oxide synthase (NOS). This study has therefore compared the effects of aminoguanidine with the effects of two other inhibitors of NOS, L -NAME and methylguanidine, on the development of experimental diabetic nephropathy. Diabetic rats were randomised to receive no treatment, aminoguanidine (1 g/l in drinking water), L -NAME (5 mg/l in drinking water) or methylguanidine (1 g/l in drinking water). Diabetic rats had increased levels of albuminuria and urinary nitrite/nitrate excretion when compared to control rats. Renal AGEs measured by fluorescence as well as by a carboxymethyllysine reactive radioimmunoassay, were elevated in diabetic rats. No changes in inducible NOS (iNOS) protein expression were detected in experimental diabetes nor did aminoguanidine affect iNOS expression. Aminoguanidine did not affect blood glucose or HbA_1c but it did prevent increases in albuminuria, urinary nitrites/nitrates and renal AGE levels as measured by fluorescence and radioimmunoassay. L -NAME and methylguanidine did not retard the development of albuminuria, nor did they prevent increases in renal AGE levels, as assessed by fluorescence. However, these treatments did prevent increases in AGEs, as measured by radioimmunoassay. This study indicates that the renoprotective effect of aminoguanidine in experimental diabetes cannot be reproduced by L -NAME or methylguanidine. It is likely that the effect of aminoguanidine is mediated predominantly by decreased AGE formation rather than via NOS inhibition. It also raises the possibility that inhibition of fluorescent AGE formation may be more renoprotective than inhibition of the formation of carboxymethyllysine-containing AGEs. [Diabetologia (1997) 40: 1141–1151] Received: 10 April 1997 and in revised form: 18 June 1997     

葛根素降低糖尿病大鼠血清糖基化终产物水平和单核细胞趋化蛋白1含量

目的　研究葛根素对糖尿病大鼠糖基化终产物 (AGEs)水平和单核细胞趋化蛋白 1(MCP 1)表达的影响。方法　将大鼠随机分为正常对照组 (CON)、糖尿病组 (DM )、糖尿病氨基胍治疗组 (AG )和糖尿病葛根素治疗组 (PU )。腹腔注射链脲佐菌素诱导糖尿病模型 ,检测血清中AGEs(荧光法 )和MCP 1(ELISA)水平 ;病理切片PAS染色及电镜观察肾组织的病理改变。免疫组化检测肾皮质MCP 1的蛋白表达水平。结果　DM组血清AGEs和MCP 1水平较PU组和AG组明显增高 (均P <0 .0 5 ) ;电镜发现两个治疗组的肾小球基底膜和心肌细胞病理改变程度比糖尿病组轻 ;肾小球内皮细胞和系膜区MCP 1免疫组化染色阳性细胞数明显比糖尿病组少。结论　葛根素能降低糖尿病大鼠血清AGEs和MCP 1水平 ,减少肾皮质中MCP 1的表达 ,减轻肾脏和心肌的病变程度     

晚期糖基化终末产物对糖尿病大鼠主动脉结构和功能的影响

目的探讨晚期糖基化终末产物(AGEs)对主动脉血管结构和功能影响及氨基胍的保护作用。方法将80只雄性SD大鼠随机分为4组:空白对照组(A组),糖尿病组(B组),糖尿病氨基胍干预组(C组)和空白氨基胍干预组(D组),每组20只。药物应用12周观察主动脉功能和结构变化。结果与A组和D组比较,B组、C组主动脉环对去甲肾上腺素引起的收缩反应明显增强,对乙酰胆碱引起的舒张反应则均明显减弱,C组反应强度较B组明显减轻(P0.05,P0.01)。主动脉壁均有AGEs沉积,B组、C组较明显,C组较B组明显减轻(P0.01);超微结构观察显示,A组、D组主动脉内膜大致正常,B组、C组内膜破坏明显,与动脉环结果呈一致性趋势。结论糖尿病大鼠主动脉AGEs含量增多,损伤了主动脉的结构和功能,氨基胍能够减少AGEs的沉积,并对主动脉结构和功能有保护作用。     

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.     

Aminoguanidine inhibits albuminuria, but not the formation of advanced glycation end-products in skin collagen of diabetic rats

Aminoguanidine, an inhibitor of advanced glycation reactions in vitro, inhibits the development of diabetic complications in animal models of diabetes, suggesting that it acts by inhibition of advanced glycation reactions in vivo. However, effects of aminoguanidine on the formation of specific advanced glycation end-products (AGEs) in vivo have not been rigorously examined. Therefore, we studied the effects of aminoguanidine on the formation of pentosidine and N(epsilon)-(carboxymethyl)lysine (CML), measured by analytical chemical methods, in collagen of streptozotocin-diabetic Lewis rats at doses which ameliorated urinary albumin excretion, an index of diabetic nephropathy. At 12 weeks, diabetic animals had fivefold higher blood glucose, threefold higher glycated hemoglobin and fivefold higher collagen glycation, compared to metabolically healthy controls; pentosidine and CML in skin collagen were increased by approximately 30 and 150%, respectively. Administration of aminoguanidine, 50 mg/kg by daily intraperitoneal injection, significantly inhibited the development of albuminuria (approximately 60%, P < 0.01) in diabetic rats, without an effect on blood glucose or glycation of hemoglobin or collagen. Surprisingly, aminoguanidine failed to inhibit the increase in pentosidine and CML in diabetic rat skin collagen. Similar results were obtained in an independent experiment in which aminoguanidine was administered in drinking water at a dose of 0.5 g/l. We conclude that the therapeutic benefits of aminoguanidine on albuminuria may not be the result of inhibition of AGE formation.     

Depletion of nitric oxide synthase-containing neurons in the diabetic retina: reversal by aminoguanidine

Summary A close association of neuronal nitric oxide synthase-immunoreactive (nNOS-IR) neurons with the retinal vasculature has been reported and it is proposed that activation of these neurons could be the mechanism by which retinal blood flow and metabolism are linked. Further, advanced glycation end products (AGEs) have previously been shown to be increased in the diabetic retina and aminoguanidine (AG), an inhibitor of advanced glycation, has been shown to attenuate the development of AGE accumulation as well as the progression of experimental diabetic retinopathy. This study examined the effects of short (1 and 3 weeks) and long term (32 weeks) diabetes on nNOS-containing neurons of the retina using NADPH diaphorase (NADPHd) histochemistry. In addition, the effect of aminoguanidine (an inhibitor of advanced glycation and NOS) and N^G-nitro-L-arginine methyl ester (L-NAME) (a non-selective NOS inhibitor) on retinal nNOS-containing neurons was examined in short and long term control and diabetic rats. In a separate study, the effect of 2,3 diamino-phenazine (NN0028) (an inhibitor of advanced glycation, but not NOS) was examined in short term (3 weeks) diabetic rats. The number of NADPHd-positive neurons per retina was reduced after one week of diabetes and remained decreased in long term diabetic rats, an effect not observed in diabetic rats rendered euglycaemic by intensified insulin treatment. Treatment of diabetic animals with aminoguanidine or NN0028 prevented the depletion in the nNOS-containing neuron number, an effect not reproduced by L-NAME. These studies suggest that the action of AG in restoring the number of nNOS-containing retinal neurons is mediated by the inhibition of AGE formation. The depletion of nNOS-containing neurons may contribute to alterations in the autoregulation of blood flow which occurs in diabetes. [Diabetologia (1998) 41: 1419–1425] Received: 23 February 1998 and in final revised form: 4 August 1998     

糖尿病大鼠皮肤损害及其机制研究

链脲佐菌素诱导的SD糖尿病大鼠4周时皮肤已开始变薄,8周时表皮厚度已明显低于正常大鼠[(0.016_+0.006对0.041±0.007)mm,P<0.01],各时间点G2/M期的表皮细胞比例显著减少.12周时在真皮层中微血管病变常见.与同时间点正常大鼠相比,血浆晚期糖基化终末产物(AGEs)和丙二醛含量明显升高,谷胱甘肽下降(均P<0.01),皮肤糖含量、AGEs水平均显著升高(P<0.01).提示局部高糖和AGEs的蓄积,可能是糖尿病皮肤损害的重要机制.