甘氨酸对STZ诱导的Ⅰ型糖尿病的保护作用及其机制研究

<正>目的:本实验旨在探究甘氨酸对STZ诱导的Ⅰ型糖尿病的降血糖作用及其作用机制。方法和结果:我们采用链脲佐菌素(STZ,50 mg/kg)腹腔注射(连续5 d)C57小鼠建立Ⅰ型糖尿病模型,造模完成后腹腔注射给予小鼠80 mg/kg、400 mg/kg和800 mg/kg甘氨酸,每周检测各组小鼠空腹血糖值。实验结果显示,80 mg/kg甘氨酸对Ⅰ型糖尿病小鼠血糖无明显保护作用,     

间歇低氧小鼠胰腺β细胞凋亡及其机制的实验研究

目的: 探讨间歇低氧对小鼠胰腺β细胞凋亡的影响及其可能机制。方法: 将30只雄性C57BL/6J小鼠随机分为间歇低氧组、持续低氧组和正常对照组,每组10只。实验结束后测定各组小鼠的胰岛素耐量;采用化学比色法测定胰腺组织丙二醛(MDA)含量和超氧化物歧化酶(SOD)活性;用real-time PCR检测小鼠胰腺组织中锰超氧化物歧化酶(MnSOD)和谷胱甘肽过氧化酶(GPx1) mRNA的表达水平;并用TUNEL染色检测胰腺β细胞凋亡。结果: 间歇低氧组小鼠胰岛素抵抗水平及胰腺组织中MDA水平显著高于正常对照组和持续低氧组 (P<0.01);胰腺组织SOD活性显著低于正常对照组和持续低氧组(P<0.01);抗氧化酶MnSOD和GPx1 mRNA的表达水平显著低于正常对照组和持续低氧组 (P<0.01);而胰腺β细胞凋亡率显著高于正常对照组和持续低氧组(P<0.01)。持续低氧组与正常对照组上述各种指标的比较均无显著差异(均P＞0.05)。结论: 间歇低氧可导致胰腺组织氧化应激状态和胰腺β细胞凋亡,这可能是阻塞性睡眠呼吸暂停低通气综合征患者胰岛素抵抗及2型糖尿病的病理生理基础之一。     

人α1-抗胰蛋白酶在胰岛β细胞移植中免疫抑制和保护作用的研究

 目的：探讨人α1-抗胰蛋白酶（hAAT）蛋白在胰岛β细胞移植中的免疫抑制和保护作用。方法：构建稳定表达hAAT蛋白的NIT-hAAT细胞系。将NIT-1细胞系和NIT-hAAT细胞系分别2次腹腔注射正常BALB/c小鼠,诱导细胞毒性T淋巴细胞(CTL)产生,将丝裂霉素处理后的2种细胞系与CTL混合培养,流式细胞术检测NIT-hAAT细胞凋亡情况;ELISA检测细胞因子表达;实时荧光定量PCR检测炎症因子mRNA表达。将2种细胞系分别植入糖尿病模型小鼠左肾包膜内,动态观察血糖和体重变化、血清中胰岛素和C肽水平以及移植部位的病理学变化。结果：CTL实验中,NIT-hAAT细胞受体鼠淋巴细胞的细胞毒作用较NIT-1细胞受体鼠明显减轻。hAAT具有减轻细胞凋亡、抑制炎症因子IL-1β、IL-6 mRNA的表达以及调节Th1/Th2细胞因子平衡的作用。NIT-hAAT细胞移植到糖尿病模型小鼠后,血糖明显下降并维持至28 d,血清中胰岛素和C肽含量明显升高,移植部位炎症细胞浸润明显减轻。结论：hAAT蛋白可减轻CTL对β细胞的杀伤作用,抑制炎症因子的表达,短期内可以抑制移植物免疫排斥反应,对胰岛β细胞移植治疗糖尿病具有明显的免疫抑制和保护作用。     

大鼠胰岛素瘤实验模型的建立及其应用

目的 通过移植大鼠胰岛素瘤INS-1细胞至糖尿病小鼠肾包膜下使之形成胰岛素瘤,并诱导其发生凋亡,建立可用于研究胰岛β细胞凋亡机制的动物模型.方法 将5×106 INS-1细胞接种于链脲霉素(STZ)造模的糖尿病小鼠左肾包膜下,监测动物空腹血糖和血清胰岛素水平的变化,当血糖趋近正常后摘取动物左侧肾脏并检测其血糖和血清胰岛素水平的变化;固定包埋摘取的肾脏,进行HE染色以及胰岛素的免疫组化染色,确定胰岛素瘤模型的建立.在胰岛素瘤动物模型中,腹腔给予毒胡萝卜素(TG)或软脂酸钠(PA),监测给药后动物空腹血糖的变化,当血糖浓度出现逆转时,摘取动物左侧肾脏,通过TUNEL原位染色法检测移植瘤细胞的凋亡.结果 将INS-1细胞移植到糖尿病小鼠肾包膜下后,从第9天开始,动物空腹血糖进行性降低,血清胰岛素水平逐渐升高,当动物血糖接近至正常时,摘取动物左肾导致动物血糖显著升高,在摘取的左肾可见明显的移植瘤,免疫组织化学染色显示移植瘤细胞为胰岛素阳性.在胰岛素瘤动物模型给予TG或PA刺激后,动物空腹血糖出现逆转,显著升高,血清中胰岛素含量明显降低,摘取动物左侧肾脏后,TUNEL原位染色发现移植瘤内有明显的细胞凋亡.结论 大鼠胰岛素瘤INS-1细胞肾包膜下移植可以建立胰岛素瘤动物模型,应用此动物模型可以在体内研究胰岛β细胞凋亡的机制.     

TNFSF14对STZ诱发Ⅰ型糖尿病的影响及其机制初探

目的:以链脲佐菌素(STZ)腹腔注射小鼠,建立Ⅰ型糖尿病动物模型,探讨TNFSF14在Ⅰ型糖尿病病理发生的作用。方法:以55 mg/kg的剂量,腹腔注射STZ于野生型(WT)和TNFSF14缺陷(TNFSF14 KO)小鼠体内,连续注射5 d,并在最后一次注射的当天开始测量血糖,根据情况每周测量2～3次;在指定的时间点处死小鼠,收集胰腺组织、脾脏和胰腺淋巴结。HE染色观察胰腺组织的病理情况;流式细胞术检测脾脏和胰腺淋巴结的淋巴细胞中T细胞亚群(CD3⁺T细胞、CD4⁺T细胞以及CD4⁺FoxP3⁺调节性T细胞)的频率。结果:连续5 d注射STZ后,WT组小鼠的血糖随即急剧上升,23 d后所有小鼠均超过了正常水平,而TNFSF14 KO小鼠的血糖值相对稳定,23 d后仍有80%的小鼠维持在正常血糖水平。HE染色显示,与WT小鼠相比,TNFSF14 KO小鼠的胰岛中淋巴细胞浸润明显减少,胰岛相对完整。流式细胞术结果表明,与WT组小鼠相比,TNFSF14 KO小鼠脾脏和胰腺淋巴结淋巴细胞中的CD3     

针刺提高2型糖尿病模型大鼠胰岛β细胞胰岛素的表达

背景：针刺治疗2型糖尿病具有很好的疗效。 目的：观察针刺对2型糖尿病模型大鼠胰岛β细胞胰岛素表达的影响。 方法：将糖尿病模型大鼠按随机化原则分为针刺组、西药组、模型组,同时设置正常对照组。针刺组大鼠取足三里、内庭和胰俞穴给予针刺治疗,西药组用罗格列酮0.2 mg/kg灌胃,模型组用双蒸水2 mL/kg灌胃,均1次/d,连续4周。 结果与结论：①血糖：针刺组明显低于模型组、西药组(P < 0.05)。②血脂：针刺组胆固醇和三酰甘油低于模型组 (P < 0.05);高密度脂蛋白胆固醇明显高于模型组(P < 0.01)。针刺组三指标与西药组比较差异无显著性意义。③胰岛β细胞胰岛素表达：针刺组显著高于模型组和西药组(P < 0.05)。④胰岛形态：模型组与西药组胰岛结构不完整,结构破坏,胰岛素染色效果差;针刺组胰岛结构趋向完整,胰岛素染色颗粒明显。说明针刺可显著提高2型糖尿病模型大鼠胰岛β细胞胰岛素表达水平,有效改善胰岛β细胞功能。     

2型糖尿病神经病理性痛C57BL/6J小鼠模型的建立

目的利用胃饲酒精和腹腔注射链脲佐菌素(streptozotocin,STZ)建立2型糖尿病神经病理性痛C57BL/6J小鼠模型。方法 80只C57BL/6J小鼠随机分为:对照组(n=15)和实验组(n=65)。对照组每日胃饲生理盐水,12周后单次空腹腹腔注射柠檬酸缓冲液;实验组每日胃饲酒精12周诱导胰岛素抵抗,继以不同剂量链脲佐菌素(40 mg/kg、50 mg/kg、60 mg/kg)腹腔注射1次,于不同时间点分别测体重、血糖、血胰岛素浓度,计算胰岛素抵抗指数、机械缩足阈值和热缩足潜伏期的变化。结果连续胃饲酒精12周后,实验组小鼠体重明显增加,空腹胰岛素浓度升高,胰岛素抵抗指数升高,血糖未升高,机械缩足阈值和热缩足潜伏期无变化。注射STZ后,40 mg/kg剂量组血糖升高但不能长期维持,60 mg/kg剂量组血糖较高,死亡率高;50 mg/kg剂量组血糖中度升高且相对稳定,胰岛素浓度和胰岛素敏感性均降低,其机械缩足阈值和热缩足潜伏期均低于基础值和对照组(P0.05)。结论连续酒精胃饲12周后联合腹腔注射STZ50 mg/kg可以建立理想的2型糖尿病神经病理性痛小鼠模型。     

当归多糖对D-半乳糖致小鼠胰腺损伤的保护作用

目的 探讨当归多糖（ASP）对D-半乳糖（D-gal）致小鼠胰腺损伤的保护作用。 方法 雄性C57BL/6 J 小鼠随机分为3组,每组10只。D-gal组: 小鼠皮下注射- gal (120 mg/kg, qd×42 d）; ASP+D-gal组: D-gal注射时间与剂量同D-gal模型组,从模型复制第16天起,腹腔注射ASP(40 mg/kg,qd×27 d）;正常对照组: 小鼠皮下注射等量与等时的生理盐水。各组给药完成后第2天检测相关指标,取外周血检测空腹血糖含量并行口服葡萄糖耐量测定（OGTT）;取胰腺称湿重计算脏器指数;制备石蜡切片,HE染色观察胰腺组织病理结构,图像分析法计数胰岛内有核细胞数和相关面积;制备胰腺组织匀浆,检测丙二醛(MDA)含量和总抗氧化能力（T-AOC）。 结果 从注射D-gal第16天开始,腹腔注射ASP共27 d（ASP+D-gal组）,小鼠胰腺湿重与脏器指数明显降低,组织病理损伤减轻;空腹血糖显著下降;在30 min和120 min的OGTT水平差别不明显;OGTT曲线下面积（AUC）降低;胰岛内有核细胞数减少,单个细胞面积减小;T-AOC活性上升,MDA含量下降。 结论 D-gal可致胰腺结构损伤和功能衰退,ASP能拮抗D-gal从而减轻对胰腺的损伤,其机制可能与减轻氧化损伤有关。     

牛磺熊去氧胆酸减轻2型糖尿病小鼠肝细胞凋亡

目的观察牛磺熊去氧胆酸(TUDCA)对自发性2型糖尿病小鼠肝细胞凋亡的影响,并探讨其作用机制。方法将db/db和db/m(lean)小鼠随机分为对照组和TUDCA处理组。TUDCA处理组每天灌胃给予500 mg/kg TUDCA,连续治疗2周。检测空腹血糖和胰岛素水平;检测肝脏组织丙二醛(MDA)、活性氧(ROS)和超氧化物歧化酶(SOD)水平;用油红O染色观察肝组织脂质沉积;用TUNEL检测肝细胞凋亡;用real-time PCR和免疫组化法检测肝组织C-JUN和XBP-1的转录和表达水平;用光镜观察肝脏组织形态和超微结构改变。结果与lean对照组相比,db/db对照组空腹血糖、转氨酶、MDA和ROS活性升高;胰岛素和SOD活性降低(P0.05);C-JUN和XBP-1表达上调;肝细胞脂滴和凋亡细胞明显增多。与db/db对照组相比,db/db TUDCA处理组空腹血糖、转氨酶、MDA和ROS活性降低;胰岛素和SOD活性升高(P0.05);C-JUN和XBP-1表达下调;肝细胞脂滴和凋亡细胞明显减少。结论 TUDCA可通过抑制肝细胞凋亡减轻2型糖尿病小鼠肝损伤,其机制可能与抑制氧化应激反应、下调C-JUN与XBP-1基因表达有关。     

R6/2型亨廷顿病转基因小鼠胰岛β细胞功能损伤

目的：研究R6/2型亨廷顿病(HD) 转基因小鼠胰岛β细胞的功能,揭示HD转基因小鼠继发糖尿病的机制。方法：利用R6/2 型HD转基因小鼠模型,检测正常和HD小鼠空腹血糖以及血清胰岛素水平;并应用HE染色和免疫荧光技术分析正常和HD小鼠胰岛形态学差异。结果：与正常小鼠相比,R6/2 型HD小鼠空腹血糖显著增高,血清胰岛素水平明显降低,胰岛萎缩,β细胞数量减少,细胞功能指数降低,而胰岛素抵抗指数正常。结论：胰岛β细胞功能损伤是引起R6/2 HD转基因小鼠继发糖尿病发生的主要因素。     

Complete Freund's adjuvant has a differential amplification action on the induction of diabetes by streptozotocin in various murine strains: CFA amplifies STZ in murine diabetes

The effect of complete Freunds Adjuvant (CFA) has been investigated on the multi-low-dose streptozotocin (STZ) model of diabetes in mice of the H-2b (C57Bl/6) and of the H-2k (A/J, CBA) genotypes. Physiological (glycemia and body weight) and morphological (insulitis) parameters were monitored. STZ was used at standard and sub-diabetogenic dose levels (45 and 22.5 mg/kg STZ, for five consecutive days respectively) and CFA was given as a single dose (0.1 ml) on the first dosage day. In H-2k mice, CFA was synergistic with STZ at 45 mg/kg but did not cause the 22.5 mg/kg dose to raise glycemia to diabetic levels. By comparison, CFA was not synergistic with STZ at 45 mg/kg in H-2b mice, but did convert the subdiabetogenic dose to a diabetogenic action in these animals. Histologically, it was noted that insulitis was a more prominent and persistent feature of the H-2k mice. It occurred at the subdiabetogenic dose level of STZ in H-2k mice, in the absence of increased glycemia, suggesting that these two phenomena are not related. CFA, either alone, or with STZ, caused severe persistent perilobular inflammation of the exocrine pancreas. It did not increase the incidence or severity of insulitis. A possible mechanism whereby CFA is synergistic with STZ at different doses in H-2b and H-2k mice is suggested.     

Essential pathogenic role of endogenous IL-18 in murine diabetes induced by multiple low doses of streptozotocin. Prevention of hyperglycemia and insulitis by a recombinant IL-18-binding protein: Fc construct

IL-18 is a cytokine structurally and functionally related to IL-1 that, in synergy with IL-12, stimulates the synthesis of IFN-gamma from T lymphocytes and natural killer cells. Because IFN-gamma plays a key pathogenic role in the development of murine immunoinflammatory diabetes induced by multiple low doses of streptozotocin (STZ) we investigated the effect of negating the actions of endogenous IL-18 in this model by administering recombinant IL-18-binding protein:Fc (IL-18 bp:Fc). C57BL/6 mice were injected once daily with 40 mg/kg STZ for 5 consecutive days, day 0 being the first day of STZ challenge. Relative to control animals treated in parallel with either PBS or human IgG, mice treated from day -3 to day 7 with daily doses of 150 microg of IL-18 bp:Fc exhibited lower incidence of diabetes and milder insulitis. In contrast, mice that were treated with IL-18 bp:Fc from day 7 to day 14 exhibited clinical and histological signs of STZ-induced diabetes similar to those of control mice treated with IgG. The protective effect of IL-18 bp:Fc was accompanied by modified ex vivo immune responses, in that spleen cells and peritoneal macrophages contained fewer IFN-gamma secreting cells and released lower amounts of nitrite (an index of nitric oxide production) and IL-1beta. We conclude that intact IL-18 function is essential for the full diabetogenic effect of low dose STZ in C57BL/6 mice.     

一种建立小鼠2型糖尿病心肌病模型的方法

目的:采用连续喂养高脂饮食(high-fat diet,HFD)结合单次腹腔注射链脲佐菌素(streptozotocin,STZ)的方法建立小鼠2型糖尿病心肌病模型。方法:将40只5~6周龄C57BL/6J雄性小鼠随机分成2组(每组各20只):对照(control)组,持续以普通饲料喂养;HFD+STZ组,持续以HFD喂养,并于造模第5周注射STZ(100mg/kg)。于造模实验开始(第0周)、第5周、第6周、第11周和第16周,测量体重和血糖,并于第11周和第16周分别对control组和HFD+STZ组小鼠进行心功能检测、胰岛素水平检测、组织学观察和心肌细胞凋亡分析。结果:造模过程中HFD+STZ组小鼠各时期的体重均大于control组(P0.05),注射完STZ后小鼠体重略有下降,但仍高于control组。注射STZ 1周后,HFD+STZ组小鼠空腹血糖值均持续高于13.89 mmol/L。在造模第11周和16周时,HFD+STZ组小鼠胰岛素水平与control组相比均有降低(P0.05)。心功能检测、组织学观察和心肌细胞凋亡分析显示,造模第11周时,HFD+STZ组小鼠的超声、心肌细胞面积和凋亡率等指标与control组相比变化不明显;造模第16周,HFD+STZ组小鼠出现心室功能障碍,心肌细胞肥大,心肌细胞的面积和心肌细胞凋亡率明显大于control组(P0.05)。结论:采用连续喂养HFD结合单次注射STZ可成功建立小鼠2型糖尿病心肌病模型。     

孕酮对小鼠认知能力及星形胶质细胞表达的影响

目的研究孕酮对成年雌性去卵巢小鼠认知能力的影响,及其与星形胶质细胞GFAP免疫阳性细胞表达是否存在关联性。方法 60只雌性昆明小鼠随机分为5组,除假手术对照组(SHAM组)外,其余各组小鼠行双侧卵巢切除术。术后对各组小鼠分别腹腔注射不同剂量孕酮或生理盐水。用Y-型电迷宫测试系统测定小鼠的认知功能变化,免疫组化法测定星形胶质细胞(astrocytes,AC)标志物胶质纤维酸性蛋白(GFAP)免疫阳性细胞的表达和变化。结果小鼠认知功能测定中,去卵巢对照组(OVX组)小鼠与SHAM组小鼠相比,在第2、3时段正确反应次数显著降低(P<0.05),高孕酮剂量组(HP组)小鼠与OVX组相比,在第3时段正确反应次数显著增高(P<0.05);GFAP表达测定中,OVX组与SHAM组小鼠相比,GFAP阳性细胞AOD和阳性细胞面积表达水平增加(P<0.05),孕酮中剂量组(MP组)和HP组与OVX组小鼠相比,GFAP阳性细胞AOD和阳性细胞面积表达水平降低(P<0.05)。结论雌、孕激素的缺乏会引起成年雌性小鼠认知障碍,孕酮的长期补充治疗可以改善小鼠认知能力,其作用机制与星形胶质细胞的变化相关。     

Protective effects of epigallocatechin gallate (EGCG) on streptozotocin-induced diabetic nephropathy in mice

There is increasing evidence suggesting that antioxidants in green tea extracts may protect kidneys on the progression of end-stage renal disease. We investigated the protective impacts of (−)-epigallocatechin 3-O-gallate (EGCG) against streptozotocin (STZ)-induced diabetic nephropathy in mice. The mice were divided into 5 groups (n = 10 per group): control (saline, i.p.), STZ (200 mg/kg, i.p.), EGCG50 (50 mg/kg, S.Q.), EGCG100 (100 mg/kg, S.Q.), and EGCG200 (200 mg/kg, S.Q.). Animals were sacrificed at scheduled times after EGCG administration and then quantitative and qualitative analysis were performed. Compared with the control group, the STZ group showed an increase in levels of blood glucose, blood urea nitrogen, creatinine and urine protein amounts with a decrease in body weight. All the above parameters were significantly reversed with EGCG treatment, especially in the EGCG100 group. After STZ injection, there was a mesangial proliferation with increased renal osteopontin accumulation and its protein expression in the glomeruli and the proximal tubules. Mice kidneys after EGCG-treatment showed a reduced expression of above parameters and relatively improved histopathological findings. These results indicated that EGCG 100 mg/kg might provide an effective protection against STZ-induced diabetic nephropathy in mice by osteopontin suppression.     

Accelerated diabetes in non-obese diabetic (NOD) mice differing in incidence of spontaneous disease.

The NOD mouse is an established model of autoimmune diabetes mellitus. Various lines of NOD mice differ in their incidence of spontaneous diabetes, e.g. 93% of female NOD/Lt mice compared with 46% of female NOD/Wehi mice develop diabetes by 250 days. These two lines were studied under conditions which greatly accelerate the onset of hyperglycaemia. It was hoped that their responses to these manipulations would reveal characteristic differences which would increase our understanding of diabetes resistance in the low incidence NOD/Wehi line. One dose of 300 mg/kg of cyclophosphamide (CP) produced hyperglycaemia in 50% of NOD mice within 2 weeks in both lines. They were also equally susceptible to diabetes induced by splenocyte transfer at 21 days of age from prediabetic 150-day-old NOD/Lt or NOD/Wehi females. Five daily 40 mg/kg doses of streptozotocin (STZ) resulted in a severity of diabetes in the NOD mice greater than in C57BL or SJL/mice. While the incidence and severity of diabetes induced in the two NOD lines were similar, this appeared to be principally due to sensitivity to the toxic effects of STZ rather than its ability to exacerbate autoimmune beta cell destruction. It has previously been shown that it is possible to prevent diabetes in susceptible NOD mice with simple, relatively benign therapies and here we show that it is possible to induce diabetes in resistant animals at a rate indistinguishable from fully predisposed individuals. It therefore appears that the prediabetic NOD mouse is poised in an immunologically precarious state with the onset of disease being highly dependent on factors which exacerbate or moderate autoimmune destruction.     

Prolactin regulation of the expression of TNF-alpha, IFN-gamma and IL-10 by splenocytes in murine multiple low dose streptozotocin diabetes

Previously, the hormone prolactin (PRL) has been found to protect against development of type 1 diabetes induced by multiple injections of streptozotocin (STZ) in mice. To further investigate this effect of PRL, C57BL/Ks mice were injected intraperitoneally with STZ (40 mg/kg body weight) or NaCl for 5 days and PRL (4 mg/kg body weight) or NaCl for 14 days. On day 15, splenocytes were isolated from the in vivo treated mice. Spleen cell preparations depleted in erythrocytes and macrophages were stained for cytoplasmic TNF-alpha, IFN-gamma and IL-10 and analyzed with flow cytometry. Isolated spleen cells were also cultured (RPMI 1640+10% fetal bovine serum) for 24 h. Thereafter, cytokine mRNA expression by the spleen cells was measured by real-time PCR and cytokine secretion determined by enzyme linked immunosorbent assay (ELISA). Freshly isolated spleen cell preparations from PRL and STZ+PRL treated animals seemed to have an increased frequency of IL-10 positive cells compared to controls. In cultured spleen cells isolated from STZ treated mice, IFN-gamma and IL-10 mRNA expression was up-regulated. PRL treatment down-regulated the mRNA expression of these cytokines and also TNF-alpha in the splenocytes obtained from animals treated with STZ. The accumulation of these cytokines in the cultures of the explanted splenocytes showed only minor differences between the experimental groups. Overall, the data seems to favor the view that PRL enhanced a Th2 response, which may reflect the preventive effect of PRL against development of multiple low dose STZ diabetes in mice.     

Difference in glucose intolerance between C57BL/6J and ICR strain mice with streptozotocin/nicotinamide-induced diabetes

Blood glucose and plasma insulin levels between C57BL/6J and ICR strain mice with nicotinamide (NA) and streptozotocin (STZ)-induced diabetes were compared to establish a suitable strain of the experimental diabetic mouse model. The mice were intraperitoneally treated twice with STZ (100 mg/kg) 15 min after injection of NA (120 mg/kg) at a 1-day interval, and non-fasting blood glucose level was then weekly monitored for 5 weeks. The blood glucose level in ICR mice gradually increased and was about 2-times higher than that in C57BL/6J mice at the end of the observation. The plasma insulin level in ICR mice was comparatively low, compared with that in C57BL/6J mice. ICR mice were also markedly glucose-intolerant when oral glucose tolerance test was performed. These results indicate that ICR strain is more sensitive than C57BL/6J strain as a mouse model with NA/STZ-induced mild diabetes.     

A new animal model of non-insulin-dependent diabetes mellitus with hypertension: neonatal streptozotocin treatment in spontaneously hypertensive rats.

Streptozotocin (STZ) treatment on neonatal rats produces a non-insulin-dependent diabetes mellitus (NIDDM) model in adulthood. Applying this model to spontaneously hypertensive rats (SHR), we designed the present study to develop a new model of NIDDM with genetic hypertension. Two-day-old male and female SHR were intraperitoneally injected with 25.0-75.0mg/kg STZ, and two-day-old Wistar Kyoto rats (WKY) of both sexes, which are a normotensive control strain for SHR, were similarly injected with 75.0-150.0mg/kg STZ. Control rats received vehicle alone. The relationships between the doses of the STZ injected and the changes of the metabolic variable and blood pressure were examined for 12 weeks following the treatment. Plasma glucose levels in male SHR increased in a dose-dependent manner at 12 weeks, control 122 +/- 8 (SEM) mg/dl, 25.0mg/kg STZ 139 +/- 13mg/dl (ns), 37.5mg/kg STZ 240 +/- 51mg/dl (ns), 50.0mg/kg STZ 359 +/- 39mg/dl (p less than 0.01), 62.5mg/kg STZ 419 +/- 33mg/dl (p less than 0.001) and 75.0mg/kg STZ 513 +/- 10mg/dl (p less than 0.001), whereas in male WKY, only mild hyperglycemia developed in case of the higher doses of STZ given, control 112 +/- 4mg/dl, 75.0mg/kg STZ 136 +/- 18mg/dl (ns), 100.0mg/kg STZ 204 +/- 40mg/dl (ns), 125.0mg/kg STZ 219 +/- 37mg/dl (p less than 0.05), and 150.0mg/kg STZ 177 +/- 12mg/dl (p less than 0.01). The development of hypertension was not affected by the neonatal STZ treatment in male SHR at 11 weeks, systolic blood pressure being control 210 +/- 7mmHg, 25.0mg/kg STZ 217 +/- 5mmHg (ns), 37.5mg/kg STZ 202 +/- 3mmHg (ns), 50.0mg/kg STZ 216 +/- 6mmHg (ns), 62.5mg/kg STZ 210 +/- 6mmHg (ns), and 75.0mg/kg STZ 209 +/- 5mmHg (ns). For the long-term observation, STZ-treated male SHR were divided into mild diabetes group (plasma glucose at 12 weeks less than 300mg/dl, mean 195 +/- 21mg/dl) and severe diabetes group (greater than or equal to 300mg/dl, mean 445 +/- 18mg/dl). Hyperglycemia in both groups was maintained until 28 weeks, plasma glucose being control 112 +/- 4mg/dl, mild diabetes group 161 +/- 10mg/dl (p less than 0.01), and severe diabetes group 419 +/- 25mg/dl (p less than 0.001) but it later gradually ameliorated, plasma glucose at 52 weeks being control 120 +/- 3mg/dl, mild diabetes group 131 +/- 7mg/dl (ns), and severe diabetes group 220 +/- 43mg/dl (ns). However, hypertension persisted in both diabetes groups until 52 weeks, systolic blood pressure being control 209 +/- 6mmHg, mild diabetes group 199 +/- 9mmHg (ns), and severe diabetes group 221 +/- 6mmHg (ns).(ABSTRACT TRUNCATED AT 400 WORDS)     

Functional photoacoustic microscopy of diabetic vasculature

We used functional photoacoustic microscopy to image diabetes-induced damage to the microvasculature. To produce an animal model for Type 1 diabetes, we used streptozotocin (STZ), which is particularly toxic to the insulin-producing beta cells of the pancreas in mammals. A set number of ND4 Swiss Webster mice received intraperitoneal injections of STZ for five consecutive days at 50 mg/kg. Most mice developed a significant rise in blood glucose level (≈ 400 mg/dL) within three weeks of the first injection. Changes in vasculature and hemodynamics were monitored for six weeks. The mouse ear was imaged with an optical-resolution photoacoustic microscope at a main blood vessel branch from the root of the ear. There are noticeable and measurable changes associated with the disease, including decreased vessel diameter and possible occlusion due to vessel damage and polyurea. We also observed an increase in the blood flow speed in the vein and a decrease in the artery, which could be due to compensation for the dehydration and vessel diameter changes. Functional and metabolic parameters such as hemoglobin oxygen saturation, oxygen extraction fraction, and oxygen consumption rate were also measured, but showed no significant change.