尼克酰胺-N-甲基转移酶在链脲佐菌素致糖尿病猴胰岛中的高表达及意义

目的： 本文旨在明确尼克酰胺-N-甲基转移酶（NNMT）在链脲佐菌素（STZ）致糖尿病猴胰腺中的表达及其定位，进而分析NNMT在β细胞损伤中的重要作用。方法： 应用基因芯片技术筛选STZ致糖尿病猴胰腺组织差异表达基因，选择NNMT作为研究对象。半定量RT-PCR及Western印迹法分别从mRNA及蛋白水平验证该差异，然后应用免疫组化技术观察该蛋白在胰腺内外分泌细胞中的表达情况。结果： NNMT在正常猴胰腺中仅有微弱表达，但在STZ致糖尿病猴胰腺中其mRNA及蛋白水平均明显上调。免疫组化结果显示该差异表达主要表现在胰岛β细胞分布区。结论： NNMT可以催化对维持细胞功能极为重要的尼克酰胺甲基化，其在糖尿病β细胞内表达上调可能会引起细胞内能量代谢障碍而导致β细胞损伤。     

Impaired regulation function in cardiovascular neurons of nucleus tractus solitarii in streptozotocin-induced diabetic rats

This study characterizes neural firing activity of the nucleus tractus solitarii (NTS) and baroreflex sensitivity (BRS) in streptozotocin (STZ)-induced diabetic rats relative to control rats by implantation of multi-wire electrode into rat NTS for direct monitoring of barosensitive NTS neurons before and after baroreflex system challenge by phenylephrine (PE) injection. NTS firing data is correlated with arterial pressure for both control and diabetic rats. In control rats, NTS firing rate and systolic arterial pressure correlate significantly with both pre-PE (baseline) and post-PE (p<0.01). In STZ-induced diabetic rats, positive correlation is observed only after PE injection (p<0.05). Although NTS firing rate was not significantly different between control and diabetic rats (p=0.085) in the baseline condition, it was significantly reduced in STZ-induced diabetic rats (p=0.042) with adjustment for BRS. After PE injection, NTS firing rate is significantly lower in diabetic rats relative to control rats (p<0.01). With adjustment for BRS, multivariate analysis shows that diabetes is independently associated with NTS firing rate after PE injection (p=0.034). Prior physiological and immunofluorescent studies found differing NTS data for control and diabetic rat only after PE challenge, but our data show diabetes-induced barosensitive NTS impairment in the baseline condition for STZ-induced diabetic rats. This latter finding suggests greater sensitivity of multi-wire electrode study of NTS relative to earlier methods.     

实时FQ-PCR检测链脲佐菌素诱导糖尿病小鼠模型胰腺survivin基因的表达

目的：研究链脲佐菌素（STZ）诱导的糖尿病小鼠胰腺survivin基因mRNA表达，了解其在胰岛损伤中的作用。 方法： 小剂量多次注射STZ的方法建立糖尿病小鼠模型，每周测定体重及血糖，并采用实时荧光PCR方法检测胰腺survivin基因mRNA表达水平。 结果： 正常BALB/c小鼠胰腺有survivin基因表达。STZ组体重在4周内无明显改变；血糖在第1周即明显升高；survivin表达水平在3、4周显著升高。对照组体重持续增加，血糖及survivin表达水平各周间无显著差异。 结论： 正常小鼠胰腺有survivin基因表达，STZ注射后survivin表达水平显著升高，可能与胰岛恢复有关。     

STZ诱导糖尿病大鼠肾脏CTGF表达改变及意义探讨

目的：观察STZ诱导糖尿病大鼠肾脏结缔组织生长因子(CTGF)表达改变及意义。方法:将SD大鼠分为对照(假手术)组(C组)（n=32）、糖尿病肾病组(DN组)（n=35）2组。每组再随机分为4个亚组：1周、2周、4周和8周组。观察各组大鼠血糖（BG）、24 h尿量（UV）、体重（BW）、尿白蛋白排泄(24 Ualb)、内生肌酐清除率(Ccr)、肾重(KW)、肾重/体重(KW/BW)、肾小球面积(A_G)和体积(V_G)、近端小管面积(A_T)、GBM、TBM厚度的改变，免疫组化观察CTGF和α-SMA在小球、小管的表达情况。结果：实验期间DN组BG、UV明显大于C组（P<0.01），DN组24 h Ualb（mg/24 h）、Ccr、KW、 KW/BW、A_G、V_G、A_T、小球及小管的CTGF表达均持续显著高于C组，AT在4周时达到高峰，且CTGF表达与24 Ualb、A_G、V_G、A_T等指标呈显著正相关 (r分别=0.95、0.92、0.86、0.94, 分别P<0.01、 P<0.05)。α-SMA 在DN组大鼠早期肾小管上皮细胞中表达不明显，第4周起可见少量α-平滑肌肌动蛋白(α-SMA)表达，到第8周时更明显。8周时DN组GBM和TBM明显厚于C组 (P<0.01)。结论：糖尿病早期CTGF表达增加，并可能参与介导糖尿病早期肾脏肥大，CTGF可能与随后的肾小管上皮细胞转分化和肾脏纤维化有关。     

Enhanced sensitivity to DNA damage induced by cooking oil fumes in human OGG1 deficient cells

Cooking oil fumes (COFs) have been implicated as an important nonsmoking risk factor of lung cancer in Chinese women. However, the molecular mechanism of COFs-induced carcinogenicity remains unknown. To understand the molecular basis underlying COFs-induced cytotoxicity and genotoxicity as well as the roles of hOGG1 in the repair of COFs-induced DNA damage, a human lung cancer cell line with hOGG1 deficiency, A549-R was established by using a ribozyme gene targeting technique that specifically knockdowned hOGG1 in A549 lung adenocarcinoma cells. MTT and comet assays were employed to examine cell viability and DNA damage/repair, respectively, in A549-R and A549 cell lines treated with COF condensate (COFC). RT-PCR and Western blot results showed that the expression of hOGG1 in A549-R cell line was significantly decreased compared with that in A549 cell line. The concentration of COFC that inhibited cell growth by 50% (the IC50) in the A549-R cell line was much lower than that in the A549 cell line, and more COFC-induced DNA damage was detected in the A549-R cell line. The time course study of DNA repair demonstrated delayed repair kinetics in the A549-R cell line, suggesting a decreased cellular damage repair capacity. Our results showed that hOGG1 deficiency enhanced cellular sensitivity to DNA damage caused by COFC. The results further indicate that hOGG1 plays an important role in repairing COF-induced DNA damage. Our study suggests that COFs may lead to DNA damage that is subjected to hOGG1-mediated repair pathways, and oxidative DNA damage may be involved in COF-induced carcinogenesis.     

Effects of neonatal capsaicin treatment and streptozotocin-induced diabetes on urinary bladder function in rats

A significant increase in the size and weight of the urinary bladder was observed 2 weeks after streptozotocin treatment and 2 months after neonatal capsaicin treatment. Both treatments induced a significant increase in the level of [³H]quinuclidinyl benzilate binding to muscarinic cholinergic receptors in the urinary bladder membranes. However, contractile responses of urinary bladder muscle strips to carbachol (0.3–20 μM) were not significantly affected by either treatment. On the other hand, neonatal capsaicin treatment, but not streptozotocin treatment, significantly enhanced contractile responses of bladder strips to electric field stimulation.     

糖尿病在糖尿病大鼠心肌梗死后心力衰竭形成中的效应

目的： 评估糖尿病在链脲霉素（STZ）诱导的血糖不加控制的糖尿病大鼠急性心肌梗死（AMI）后心力衰竭(HF)形成中的效应。方法：所有SD大鼠随机分组,糖尿病组经腹腔内注射STZ（65mg/kg）诱导糖尿病,70 d后所有AMI组结扎冠状动脉左前降支建立AMI模型。确定AMI前后各时点观察大鼠的生存率,心肌超微结构的变化,进行血流动力学分析、心肌纤维化测定及左心肥厚的评估。结果：结扎左冠状动脉前降支后,糖尿病大鼠的左心功能恶化及左室重构的速度均较非糖尿病大鼠显著。在早期阶段,糖尿病与非糖尿病大鼠心肌纤维化相似,而1月后却出现显著差别。结论：糖尿病大鼠AMI后心力衰竭进展明显加速。     

Glycerol reduces food intake in diabetic rats

Streptozotocin diabetic rats received four daily subcutaneous injections of glycerol or a glycerol solution in place of water for a seven day period. Both night and total food intake in the subcutaneous glycerol group were significantly suppressed below untreated diabetic controls. The oral glycerol group showed a nonsignificant decrease in night food intake and a significant reduction in day and total food intake. Consumption of additional fluid calories by the oral glycerol group contributed to the suppression of food intake in this group, but suppression in the subcutaneous group was unrelated to calculated calories obtained from glycerol. The oral glycerol group also consumed more of the glycerol solution than the other diabetic groups did of water. Results of this study support previous findings that subcutaneous and oral glycerol suppress food intake in normal rats although suppression with oral glycerol may have been related to caloric intake, and suggest that low plasma concentrations of insulin do not interfere with the effects obtained with glycerol in normal animals.     

DNA base excision repair activities in mouse models of Alzheimer's disease

Alzheimer's disease (AD) has been correlated with elevated levels of oxidative DNA damage. Base excision repair (BER) is the main repair pathway for the removal of oxidative DNA base modifications. We have recently found significant functional deficiencies in BER in brains of sporadic AD and amnestic mild cognitive impairment patients. In this study we tested whether altered BER activities are associated with appearance of symptoms in different brain regions of pre-symptomatic and symptomatic mice harboring mutant APP alone or in combination with Tau and PS1. Our results suggest that unlike in humans, the development of AD-like pathology in the studied mouse models is not associated with deficiencies in BER.     

The influence of cyclosporin A on the vascular permeability of the pancreatic islets and on diabetes induced by multiple low doses of streptozotocin in the mouse

Summary The aim of the present study was to investigate the influence of cyclosporin A on the course of multiple low dose streptozotocin induced diabetes in mice, an animal model for human type I diabetes mellitus. C57BL/Ks mice were treated on five consecutive days with intraperitoneal injections of steptozotocin or citiric acid buffer. Thirty min before the injections the animals were given cyclosporin A (10 or 50 mg/kg body weight) or saline. Cyclosporin A did not protect against the hypoglycaemia and at the higher dose it potentiated the diabetogenic effect. Furthermore, cyclosporin A did not affect the development of insulitis when the pancreatic glands were examined by light microscopy. Using a technique for monitoring vascular permeability in vivo with the aid of the pigment Monastral Blue B, it was found that the development of diabetes was accompanied by an increased vascular leakage. Control animals treated with cyclosporin A also showed an increased islet staining with Monastral Blue B. The data indicate that cyclosporin A potentiates diabetes induced by low doses of streptozotocin. This can be attributed to a direct toxic effect of cyclosporin A on the pancretic B-cells and may also be due to an increased vascular leakage induced by cyclosporin A. The latter would allow an increased migration of inflammatory cells into the islets and the consequent release of B-cytotoxic substances.This work was supported by grants from the Swedish Diabetes Association, the Swedish Medical Research Council (12X-109, 12X-8273; 12P-7680), the Clas Groschinsky Memorial Foundation, the Nordic Insulin Fund, the Ernfors Family Fund, the Swedish Society of Medicine and the Hoechst Diabetes Foundation     

Increases in PKC gamma expression in trigeminal spinal nucleus is associated with orofacial thermal hyperalgesia in streptozotocin-induced diabetic mice

Painful diabetic polyneuropathy (PDN) at the early phrase of diabetes frequently exhibits increased responsiveness to nociception. In diabetic patients and animal models, alterations in the transmission of orofacial sensory information have been demonstrated in trigeminal system. Herein, we examined the changes of protein kinase Cγ subunit (PKCγ) in trigeminal spinal nucleus (Sp5C) and observed the development of orofacial thermal sensitivity in streptozotocin (STZ)-induced type 1 diabetic mice. With hyperglycemia and body weight loss, STZ mice exhibited orofacial thermal hyperalgesia, along with increased PKCγ expression in Sp5C. Insulin treatment at the early stage of diabetes could alleviate the orofacial thermal hyperalgesia and impaired increased PKCγ in Sp5C in diabetic mice. In summary, our results demonstrate that PKCγ might be involved in orofacial thermal hyperalgesia of diabetes, and early insulin treatment might be effective way to treat orofacial PDN.     

Combination therapy of Nigella sativa and human parathyroid hormone on bone mass, biomechanical behavior and structure in streptozotocin-induced diabetic rats

Extracts of the seeds of Nigella sativa (NS), an annual herbaceous plant of the Ranunculaceae family, have been used for many years for therapeutic purposes, including their potential anti-diabetic properties. The aim of the present study was to test the hypothesis that combined treatment with NS and human parathyroid hormone (hPTH) is more effective than treatment with NS or hPTH alone in improving bone mass, connectivity, biomechanical behaviour and strength in insulin-dependent diabetic rats. Diabetes was induced by intraperitoneal injection of streptozotocin (STZ) at a single dose of 50mg/kg. The diabetic rats received NS (2ml/kg/day, i.p.), hPTH (6microg/kg/day, i.p.) or NS and hPTH combined for 4 weeks, starting 8 weeks after STZ injection. The beta-cells of the pancreatic islets of Langerhans were examined by immunohistochemical methods. In addition, bone sections of femora were processed for histomorphometry and biomechanical analysis. In diabetic rats, the beta-cells were essentially negative for insulin-immunoreactivity. NS treatment (alone or in combination with hPTH) significantly increased the area of insulin immunoreactive beta-cells in diabetic rats; however, hPTH treatment alone only led to a slightly increase in the insulin-immunoreactivity. These results suggest that NS might be used in a similar manner to insulin as a safe and effective therapy for diabetes and might be useful in the treatment of diabetic osteopenia.     

Repair of persistent strand breaks in the mitochondrial genome

Oxidative DNA damage has been attributed to increased cancer incidence and premature aging phenotypes. Reactive oxygen species (ROS) are unavoidable byproducts of oxidative phosphorylation and are the major contributors of endogenous oxidative damage. To prevent the negative effects of ROS, cells have developed DNA repair mechanisms designed to specifically combat endogenous DNA modifications. The base excision repair (BER) pathway is primarily responsible for the repair of small non-helix distorting lesions and DNA single strand breaks. This repair pathway is found in all organisms, and in mammalian cells, consists of three related sub-pathways: short patch (SP-BER), long patch (LP-BER) and single strand break repair (SSBR). While much is known about nuclear BER, comparatively little is known about this pathway in the mitochondria, particularly the LP-BER and SSBR sub-pathways. There are a number of proteins that have recently been found to be involved in mitochondrial BER, including Cockayne syndrome proteins A and B (CSA and CSB), aprataxin (APTX), tryosyl-DNA phosphodiesterase 1 (TDP1), flap endonuclease 1 (FEN-1) and exonuclease G (EXOG). These significant advances in mitochondrial DNA repair may open new avenues in the management and treatment of a number of neurological disorders associated with mitochondrial dysfunction, and will be reviewed in further detail herein.     

Effects of melatonin on streptozotocin-induced diabetic liver injury in rats

This study investigated the possible protective effects of melatonin as an antioxidant against streptozotocin (STZ)-induced diabetic liver injury in rats. Wistar rats were divided into four groups: untreated control (UC), melatonin-treated control (MC), untreated diabetic (UD), and melatonin-treated diabetic (MD). Experimental diabetes was induced by a single-dose (60 mg/kg, intraperitoneally (ip)) STZ injection, and melatonin was injected (200 microg/kg/day, ip) for 4 weeks. Upon light and electron microscopic examination, we observed that melatonin improved the morphological and histopathological changes of the liver caused by diabetes. Malondialdehyde levels in the liver homogenates of UD rats were higher than those of controls and were markedly reduced after melatonin treatment. Although no significant difference was observed with respect to antioxidant status, the superoxide dismutase activity tended to be higher in the UD rats than in the treated rats. Our findings showed that melatonin administration partially reduced liver injury in STZ-induced diabetic rats.     

大豆异黄酮对I型糖尿病甲基乙二醛水平及白内障并发症的影响

目的：甲基乙二醛（MG）是糖代谢产生的毒性副产物,本研究旨在探讨大豆异黄酮是否通过降低MG的产生而发挥对I型糖尿病的防治作用。方法：链脲佐菌素诱导I型糖尿病大鼠模型,给予含不同剂量大豆异黄酮的大鼠饲料喂养,按大豆异黄酮不同剂量随机分为3组：大豆异黄酮低剂量组（diabetes+LIS）,大豆异黄酮高剂量组（diabetes+HIS）及模型组（diabetes）。治疗8周后处死大鼠,留取血清测定血糖、糖化血红蛋白、还原型谷胱甘肽（GSH）、胰岛素水平,HPLC法测定血清MG水平,免疫组化法检测胰岛β细胞胰岛素表达情况。结果：与模型组或diabetes+LIS组大鼠比较,HIS组大鼠血清胰岛素水平明显上升［(2.46±0.35)μg/L vs (0.55±0.04)μg/L or (0.39±0.04) μg/L, 均P<0.01］,血糖明显下降［(19.50±1.85)mol/L vs (28.24±3.56) mol/L or (26.94±1.82) mmol/L, 均P<0.05］、糖化血红蛋白减低［（13.14±3.00)% vs (17.16±2.60)% or (17.29±4.12)%, 均P<0.05］,血清MG明显降低 ［(0.77±0.09)nmol/L vs (1.57±0.17)nmol/L or (1.91±0.28)nmol/L,均P<0.05］,而血清GSH 水平明显增加［(13.26±1.61)mmol/L vs (7.35±1.55)mmol/L or (5.54±1.10) mmol/L, 均P<0.01］,diabetes+HIS 组大鼠胰岛β细胞中胰岛素表达水平也明显增加。Diabetes+HIS 组大鼠白内障的发生率明显低于模型组（P<0.05）。模型组与diabetes+LIS组比较,上述指标均无显著差异。结论：大豆异黄酮对I型糖尿病具有治疗作用,并能降低I型糖尿病大鼠白内障的发生率,其机制可能与胰岛素水平增加、MG水平降低及抗氧化作用有关。     

氧化应激在糖尿病大鼠胃动力变化中的意义

 目的：观察糖尿病大鼠胃组织中氧化应激水平,探讨氧化应激对糖尿病胃动力和胃Cajal间质细胞（ICC）的影响。方法：38只8周龄雄性SD大鼠腹腔注射链脲佐菌素（STZ）,选取造模成功的36只大鼠分为糖尿病组和糖尿病治疗组,每组18只,另取同批正常SD大鼠18只作为正常对照组。检测各组大鼠体重、血糖和糖化血红蛋白。实验第1周末和第10周末分别处死各组9只大鼠测定胃排空率,以及胃平滑肌中丙二醛（MDA）、超氧化物歧化酶（SOD）、肿瘤坏死因子α（TNF-α）、酪氨酸激酶受体c-Kit和干细胞因子（SCF）水平。通过免疫细胞化学和原位末端标记（TUNEL）法检测胃组织ICC凋亡。结果：与正常组比较,糖尿病大鼠胃动力明显减弱。糖尿病大鼠胃平滑肌内MDA含量升高,SOD活性减弱,TNF-α含量升高,c-Kit和SCF水平下降,ICC凋亡明显增加。糖尿病大鼠治疗后氧化应激水平降低,抗氧化能力提高,c-Kit和SCF水平显著升高,ICC凋亡减少。抗氧化治疗后胃动力明显改善,与糖尿病组比较有明显差异。结论：高血糖影响大鼠胃组织中抗氧化酶的表达。氧化应激水平在糖尿病胃组织中明显增强,在糖尿病大鼠胃动力变化中发挥重要作用。氧化应激促使c-Kit/SCF系统受损,导致胃平滑肌ICC凋亡增多。     

Effect of antisense TGF-beta1 oligodeoxynucleotides in streptozotocin- induced diabetic rat kidney

Transforming growth factor (TGF)-beta1 is an important fibrogenic factor that is involved in the pathogenesis of diabetic nephropathy. We evaluated the effect of circular antisense TGF-beta1 oligodeoxynucleotides (ODNs) on the TGF-beta1 expression in the rat mesangial cell culture and in streptozotocin (STZ)-induced diabetic rats. Circular antisense TGF-beta1 ODNs were found to be stable in rat serum, significantly decreasing TGF-beta1 mRNA expression compared with linear antisense ODNs in the rat mesangial cell culture. Circular antisense TGF-beta1 ODNs were introduced into the tail vein of normal rats using hemagglutinating virus of Japan (HVJ)-liposome-mediated gene transfer method and were confirmed to be delivered effectively into the kidney, liver, lungs, and spleen. To inhibit the overexpression of TGF-beta1 in diabetic kidneys, we introduced circular antisense TGF-beta1 ODNs into the STZ-induced diabetic rats. On day 13 after circular antisense TGF-beta1 ODNs injection, TGF-beta1 mRNA and protein expression markedly decreased and urinary TGF-beta1 excretion rate also dropped in the circular antisense TGF-beta1 ODNs-treated diabetic rats. These results suggest that circular antisense TGF-beta1 ODNs may be a useful tool for developing new therapeutic application for progressive diabetic nephropathy.