Impaired proliferation of non-parenchymal cells participates in an impairment of liver regeneration in db/db mice

In this study, we examined the possibility that impaired proliferation of non-parenchymal cells affects in an impairment of liver regeneration in db/db mice, which are congenitally deficient in receptors for leptin. Liver regeneration after a two thirds partial hepatectomy (2/3 PH) was impaired in 10-week-old female db/db mice. The proliferation of both hepatocytes and non-parenchymal cells estimated from a bromodeoxyuridine (BrdU) labeling index was suppressed, and the protein expression of vascular endothelial growth factor was blocked in db/db mice. Although the extent of fatty change and the level of epidermal growth factor receptor protein expression in the liver were improved in 5-week-old db/db mice, the regeneration of liver was impaired after 2/3 PH in both 5- and 10-week-old db/db mice. These results suggested that suppressed proliferation of non-parenchymal cells contributes to the impairment of liver regeneration in db/db mice. As leptin has also the angiogenic effect, the angiogenic inhibitor FR-118487 was administered to ICR mice to examine liver regeneration after 2/3 PH, and the rate of regeneration was affected. In conclusion, it is suggested that the suppressed proliferation of non-parenchymal cells contributes to the impairment of liver regeneration probably through a disrupted angiogenesis in db/db mice.     

Impaired liver regeneration after partial hepatectomy in db/db mice

Fatty liver is the most common hepatic disorder in humans and supposed to be a cause of poor prognosis after liver transplantation and hepatic resection which could be resulted from impaired liver regeneration. This study was carried out to analyze the process of liver regeneration in db/db mice which show severe steatosis because of abnormal leptin receptor. We performed 70% partial hepatectomy (PH) on db/db mice and normal +m/+m mice, and then sacrificed the animals 1, 2, 3, 5, 7 and 10 days later. The liver samples were weighed and examined histologically or immunohistochemically. As a result, the liver mass restitution was significantly inhibited in db/db mice compared with +m/+m mice. The BrdU labelling index peaked at 2 days after PH in both strains, although the value was lower in db/db mice. After that, interestingly, it decreased to the control level at 5 days in +m/+m mice while the recovery was delayed in db/db mice. Similar sequence was also observed in the PCNA labelling index. In addition, the peak time of the mitosis index was 2 days and 5 days after PH in +m/+m mice and in db/db mice, respectively. Thus, although not significant, the proliferative response of hepatocytes to PH occurred somewhat more transient and sharply in +m/+m mice while it lasted somewhat longer in db/db mice. This suggests that db/db mice may be valuable as one of the animal models for the investigation of the effects of steatosis on the liver regeneration.     

甜菜碱对老龄db/db小鼠脂肪性肝损害的影响

 目的：通过高脂饮食诱发db/db小鼠非酒精性脂肪性肝病（NAFLD）模型,探索甜菜碱对遗传性小鼠脂肪肝脂质代谢的影响。方法：50只7月龄db/db鼠随机分为低、中、高剂量组、生理盐水对照组和阳性药物组。所有小鼠均饲以高脂饲料, 以诱发NAFLD 模型。 小鼠分别以200 mg/kg(低剂量组)、400 mg/kg(中剂量组)和800 mg/kg(高剂量组)甜菜碱溶液灌胃,连续6周。测定血清丙氨酸氨基转移酶(ALT)、甘油三酯(TG)、总胆固醇（TC）和低密度脂蛋白(LDL)水平,并行葡萄糖耐量测定和肝组织病理学观察。结果：甜菜碱可显著降低血清ALT、TC和LDL的水平(P<0.05或P<0.01)。组织学结果表明甜菜碱可显著减少小鼠肝细胞的脂肪样变性。结论: 甜菜碱可以显著改善老龄db/db小鼠的脂类代谢紊乱和肝功能,明显降低脂肪在肝细胞中的积蓄。     

A stereological study of the renal glomerular vasculature in the db/db mouse model of diabetic nephropathy

In diabetic nephropathy, glomerular hypertrophy is evident early in response to hyperglycaemia. Alterations of capillary length and vascular remodelling that may contribute to glomerular hypertrophy and the subsequent development of glomerulosclerosis remain unclear. The present study used the db/db mouse model of Type 2 diabetes to examine the glomerular microvascular changes apparent with long-term diabetic complications. Unbiased stereological methods and high-resolution light microscopy were used to estimate glomerular volume, and glomerular capillary dimensions including length and surface area in 7-month-old db/db diabetic mice and age-matched db/m control mice. The db/db diabetic mice showed significant glomerular hypertrophy, corresponding with elevated blood glucose levels, and increased body weight and kidney weight, compared with db/m control mice. Glomerular enlargement in db/db mice was associated with increases in the surface area (5.387 +/- 0.466 x 10(4) microm2 vs. 2.610 +/- 0.287 x 10(4) microm2; P < 0.0005) and length (0.3343 +/- 0.022 x 10(4) microm vs. 0.1549 +/- 0.017 x 10(4) microm; P < 0.0001) of capillaries per glomerulus, compared with non-diabetic mice. Stereological assessment at the electron microscopic level revealed increased glomerular volume density of mesangial cells and mesangial matrix, and thickening of the glomerular basement membrane in db/db mice. These results demonstrate that glomerular hypertrophy evident in advanced diabetic nephropathy in this model is associated with increased length and surface area of glomerular capillaries. The contribution of angiogenesis and vasculogenesis to the glomerular microvascular alterations in response to hyperglycaemia remain to be determined.     

厄贝沙坦通过诱导自噬减轻db/db小鼠肝脏脂肪变

目的:探讨厄贝沙坦对db/db小鼠脂肪肝的影响及自噬在这一过程中的作用。方法:雄性db/db小鼠24只随机分为模型组和厄贝沙坦组,另选取12只db/m小鼠作为正常对照组。各组分别干预16周后,观察体重、肝指数、血脂、肝功能以及肝脏病理的变化,检测肝组织PI3K/Akt/m TOR信号通路及自噬相关蛋白Atg-7、beclin-1和LC3B的表达情况,并利用电镜观察肝脏自噬小体的变化。结果:与模型组相比,应用厄贝沙坦干预后,db/db小鼠的体重、肝指数、血脂、丙氨酸转氨酶和天冬氨酸转氨酶与模型组相比显著降低(P0.05),肝脏病理改变明显减轻;肝组织p-PI3K、p-Akt和p-m TOR的表达明显减少,Atg-7、beclin-1和LC3B-Ⅱ的表达明显增加,肝脏自噬小体显著增多(P0.05)。结论:厄贝沙坦可能通过抑制PI3K/Akt/m TOR信号通路,上调自噬相关蛋白Atg-7、beclin-1和LC3B-Ⅱ表达,进而促进肝细胞自噬,减轻db/db小鼠肝脏脂肪变。     

db/db小鼠肝脏中实时定量逆转录PCR内参照基因及标准化方法的评估与整合（英文）

目的:实时定量逆转录PCR(RT-q PCR)结果的标准化对于保证最终结果的准确性尤其重要。常用的标准化方法包括用加入的核酸量校正(ΔCt法)、用单个内参照基因校正(ΔΔCt法)和用统计学软件计算多个内参照基因的几何平均值进行校正。我们在db/db小鼠肝脏中对各种校正方法进行评估。方法:用ge Norm和NormFinder两种软件评估ACTB、e IF5、GAPDH、HMBS、HPRT1、Polr2A和RPLP0共7个内参照基因,以肝脏脂质合成相关基因Thrsp、SCD、SREBP1c和FAS作为目的基因。结果:应用ΔCt法,db/db小鼠肝脏中所有目的基因及GAPDH的表达显著升高(P0.05)。ge Norm计算认为ACTB和HMBS最稳定。Norm Finder计算认为ACTB最稳定,而GAPDH和RPLP0为最佳组合。以单个基因ACTB或RPLP0,以及ACTB与HMBS,或GAPDH与RPLP0的几何平均值进行校正,db/db小鼠肝脏中除SREBP1c以外,Thrsp、SCD1和FAS的表达均升高(P0.05)。结论:用ΔCt法校正RTq PCR的结果稳定并具有生物学意义。统计学软件ge Norm或Norm Finder应与ΔCt法整合使用。     

Pathology of the liver in obese and diabetic ob/ob and db/db mice fed a standard or high-calorie diet

Non‐alcoholic fatty liver disease (NAFLD) is one of the commonest liver diseases in Western countries. Although leptin deficient ob/ob and db/db mice are frequently used as murine models of NAFLD, an exhaustive characterization of their hepatic lesions has not been reported to date, particularly under calorie overconsumption. Thus, liver lesions were characterized in 78 ob/ob and db/db mice fed either a standard or high‐calorie (HC) diet, for one or three months. Steatosis, necroinflammation, apoptosis and fibrosis were assessed and the NAFLD activity score (NAS) was calculated. Steatosis was milder in db/db mice compared to ob/ob mice and was more frequently microvesicular. Although necroinflammation was usually mild in both genotypes, it was aggravated in db/db mice after one month of calorie overconsumption. Apoptosis was observed in db/db mice whereas it was only detected in ob/ob mice after HC feeding. Increased apoptosis was frequently associated with microvesicular steatosis. In db/db mice fed the HC diet for three months, fibrosis was aggravated while steatosis, necroinflammation and apoptosis tended to alleviate. This was associated with increased plasma β‐hydroxybutyrate suggesting an adaptive stimulation of hepatic mitochondrial fatty acid oxidation (FAO). Nevertheless, one‐third of these db/db mice had steatohepatitis (NAS ≥ 5), whereas none of the ob/ob mice developed non‐alcoholic steatohepatitis under the same conditions. Steatosis, necroinflammation, apoptosis and fibrosis are modulated by calorie overconsumption in the context of leptin deficiency. Association between apoptosis and microvesicular steatosis in obese mice suggests common mitochondrial abnormalities. Enhanced hepatic FAO in db/db mice is associated with fibrosis aggravation.     

NGF在db/db自发性糖尿病小鼠颌下腺的表达

目的　观察转基因糖尿病小鼠颌下腺的形态学改变以及神经生长因子 (NGF)在颌下腺表达的变化。　方法　引进日本C5 7BL ksj db m表型正常隐性基因小鼠 ,近亲交配 ,其纯合子后代 ,即为db db(单基因遗传自然发病型 )糖尿病小鼠。取 3、4、6、8、10月龄db db糖尿病小鼠及相应月龄的db m正常小鼠颌下腺。HE染色及SP免疫组织化学染色后行图像分析 ,统计NGF阳性表达的细胞数。　结果　随着糖尿病发展 ,颌下腺组织萎缩 ,细胞缩小 ,形态不规则 ,排列不整齐。不同月龄糖尿病小鼠NGF阳性细胞明显低于相应对照组 (P <0 0 1) ,且逐渐减少 ,呈下降趋势。　结论　NGF阳性细胞数的减少说明颌下腺颗粒曲管细胞合成和分泌NGF功能降低 ,而NGF缺乏与糖尿病性神经病变的发生与发展密切相关。     

Blockade of IL-6 signaling exacerbates liver injury and suppresses antiapoptotic gene expression in methionine choline-deficient diet-fed db/db mice

Our previous study revealed that blockade of interleukin-6 (IL-6)-STAT3 signaling ameliorated liver injury, although hepatic STAT3(-/-) or GP130(-/-) mice have been reported to develop severe liver injury, in a murine methionine choline deficient (MCD) diet-induced model of non-alcoholic steatohepatitis (NASH). In this study, to determine whether profound blockade of IL-6-STAT3 signaling may still ameliorate liver injury, we studied db/db mice, which have impaired leptin-mediated STAT3 activation, using the MCD diet-induced NASH model. Male lean and db/db mice (6 weeks old) were fed either control chow or an MCD diet for 8 or 12 weeks. Half of the mice were treated with 15 mg/kg rat anti-mouse IL-6 receptor neutralizing antibody (MR16-1) intraperitoneally twice weekly, the remainder were injected with 15 mg/kg rat IgG as a control. Hepatic steatosis, injury, fibrosis, markers of lipid peroxidation/oxidant stress and antiapoptotic gene expression were evaluated. Plasma IL-6 levels were elevated in all groups of db/db mice. Although hepatic IL-6/ GP130 signaling was activated in chow-fed db/db mice, this was suppressed in MCD diet-fed db/db mice, accompanied by downregulation of hepatic IL-6 receptor and GP130 mRNA expression. MR16-1 treatment of MCD diet-fed db/db mice further repressed STAT3 activities and expression of STAT3-related antiapoptotic genes, such as Bcl-2 and Ref-1, but increased plasma-free fatty acid and hepatic markers of lipid peroxidation/oxidant stress, leading to increased liver injury, hepatocyte apoptosis and liver fibrosis. Although 'moderate' blockade of enhanced IL-6-STAT3 signaling may be beneficial in NASH, as we reported previously, these findings demonstrate that a profound defect in STAT3 activation is detrimental in terms of liver injury, hepatocyte apoptosis and liver fibrosis, indicating the hepato-protective role of IL-6 signaling in this severe NASH model.     

甜菊糖甙对db/db小鼠胰岛素抵抗和胰岛炎症的影响

目的：大量证据显示,胰岛的炎症反应和胰岛素抵抗是db/db小鼠发生2型糖尿病（DM2）的两个主要因素。甜菊糖甙是一种从菊科植物中提取的天然化合物对于糖尿病病人有许多益处。本实验试图观察甜菊糖甙是否能够改善db/db小鼠的胰岛素抵抗和胰岛炎症反应,从而改善糖代谢。方法：给予db/db小鼠甜菊糖甙或者空白溶剂处理2个月。在处理结束时观察空腹血糖和胰岛素耐量,同时分离胰岛行葡萄糖刺激的胰岛素分泌试验,并行胰腺组织免疫荧光观察胰岛内巨噬细胞浸润情况。结果：甜菊糖甙干预2个月不影响db/db小鼠体重,但显著降低小鼠的空腹血糖,明显改善胰岛素抵抗。同时葡萄糖刺激的胰岛素分泌试验结果提示,甜菊糖甙可显著提高db/db小鼠胰岛在体外分泌胰岛素的能力。此外,免疫荧光提示,甜菊糖甙能显著减轻db/db小鼠胰岛内巨噬细胞浸润程度明显减轻和改善胰岛炎症反应。结论：甜菊糖甙能通过改善胰岛素抵抗和胰岛炎症反应来改善db/db小鼠的糖代谢和胰岛素分泌能力。     

凋亡细胞在db/db自发性糖尿病小鼠颌下腺的分布

目的:观察凋亡细胞在db/db糖尿病小鼠颌下腺中的分布。方法:选取3、4、6、8、10月龄db/db糖尿病小鼠及相应月龄的dh/m~(?)小鼠颌下腺,应用TUNEL标记方法染色后进行图像分析.统计凋亡细胞在颌下腺组织中分布的细胞阳性率。结果:随着糖尿病的发展,颌下腺组织出现腺体萎缩及颗粒曲管数目减少,实质细胞排列不整齐,呈簇状堆集,纤维及血管增多。凋亡细胞在对照组及糖尿病组颌下腺中均有分布,糖尿病组凋亡细胞阳性率高于对照组。糖尿病组与对照组凋亡细胞阳性率随月龄增大均呈增加趋势。结论:db/db糖尿病可导致颌下腺组织萎缩及实质细胞形态学改变;凋亡细胞阳性率在糖尿病组随疾病发展而增加显著。这与糖尿病腺体萎缩和功能受损相一致。     

Japanese herbal medicines shosaikoto,inchinkoto, and juzentaihoto inhibit high‐fat diet‐induced nonalcoholic steatohepatitis in db/db mice

Few studies have investigated the effects of Japanese herbal medicines on nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH). To the best of our knowledge, only one study has examined whether high‐fat (HF) diet‐fed db/db mice are appropriate animal models of NASH. We investigated the effects of four types of Japanese herbal medicines (shosaikoto (TJ‐9), inchinkoto (TJ‐135), juzentaihoto (TJ‐48), and keishibukuryogan (TJ‐25)) on hepatic lesions of HF diet‐fed db/db mice. Db/db mice were divided into six groups: control diet (control); HF diet (HF); and HF diet supplemented with TJ‐9, TJ‐135, TJ‐48, or TJ‐25 (TJ‐9, TJ‐135, TJ‐48, and TJ‐25, respectively). Mice were killed after 6 weeks of treatment, and biochemical and pathological analyses were performed. Mice in the HF group consistently developed histopathological features consistent with definite NASH, and marked necroinflammation occurred. Serum alanine aminotransferase levels in the TJ‐9, TJ‐135, and TJ‐48 groups were significantly improved compared with those in the HF group. With regard to liver histology, TJ‐9 and TJ‐48 significantly improved lobular inflammation, and TJ‐135 significantly improved ballooning degeneration. We have shown that HF diet‐fed db/db mice are animal models that correctly recapitulate the histopathology of human NASH and that TJ‐9, TJ‐135, and TJ‐48 inhibit necroinflammatory activity in this model.     

Defective hepatic regeneration after partial hepatectomy in leptin-deficient mice is not rescued by exogenous leptin

Liver regeneration after partial hepatectomy (PH) is impaired in leptin-deficient ob/ob mice. Here, we tested whether exogenous leptin and/or correction of the obese phenotype (by food restriction or long-term leptin administration) would rescue hepatocyte proliferation and whether the hepatic progenitor cell compartment was activated in leptin-deficient ob/ob livers after PH. Because of the high mortality following 70% PH to ob/ob mice, we performed a less extensive (55%) resection. Compared to lean mice, liver regeneration after 55% PH was deeply impaired and delayed in ob/ob mice. Administration of exogenous leptin to ob/ob mice at doses that restored circulating leptin levels during the surgery and postsurgery period or for 3 weeks prior to the surgical procedure did not rescue defective liver regeneration. Moreover, correction of obesity, metabolic syndrome and hepatic steatosis by prolonged administration of leptin or food restriction (with or without leptin replacement at the time of PH) did not improve liver regeneration in ob/ob mice. The hepatic progenitor cell compartment was increased in ob/ob mice. However, after PH, the number of progenitor cells decreased and signs of proliferation were absent from this cell compartment. In this study, we have conclusively shown that neither leptin replacement nor amelioration of the metabolic syndrome, obese phenotype and hepatic steatosis, with or without restitution of normal circulating levels of leptin, was able to restore replicative competence to ob/ob livers after PH. Thus, leptin does not directly signal to liver cells to promote hepatocyte proliferation, and the obese phenotype is not solely responsible for impaired regeneration.     

2型糖尿病模型db/db小鼠海马NOS阳性神经元变化

目的　观察人类 2型糖尿病模型———C5 7BL/KsJdb/db(db/db)小鼠海马NOS阳性神经元变化。方法　糖尿病组 :6周龄C5 7BL/KsJ(db +db +)小鼠 5只 ,尾静脉空腹血糖高于 11.1mmol/L且肥胖。对照组 :非糖尿病小鼠C5 7BL/KsJ(?+) 5只 ,尾静脉空腹血糖低于 6 .0mmol/L体重正常 ,于 30周龄 (成模第 6月末 )时 ,灌注固定取脑 ,以NADPH d组化法显示海马NOS阳性神经元。结果　与正常对照组相比 ,糖尿病组小鼠海马齿状回NOS阳性神经元密度显著减少 (P <0 0 1)。结论　糖尿病时NOS阳性神经元数量减少 ,NO的合成降低表明NO可能参与糖尿病中枢神经系统功能障碍     

STAT-3 overexpression and p21 up-regulation accompany impaired regeneration of fatty livers

Fatty liver is an important cause of morbidity in humans and is linked to impaired liver regeneration after liver injury, but the mechanisms for impaired liver regeneration remain unknown. In the normal liver, the interleukin (IL)-6/STAT-3 pathway is thought to play a central role in regeneration because this pathway is disrupted in IL-6-deficient mice that exhibit impaired liver regeneration after 70% partial hepatectomy (PH). To determine whether inhibition of STAT-3 is involved in fatty liver-related mitoinhibition, regenerative induction of STAT-3 was compared in normal mice and leptin-deficient ob/ob mice that have fatty livers and markedly impaired liver regeneration after PH. In both groups, two waves of STAT-3 activation were observed, the first in endothelia and the second in hepatocytes. Before PH, a significantly higher percentage of ob/ob endothelial and hepatocyte nuclei expressed phosphorylated (activated) STAT-3. After PH, phospho-STAT-3 accumulated in liver nuclei of lean mice and this response was markedly exaggerated in ob/ob mice. Moreover, a striking inverse correlation was noted between hepatocyte nuclear accumulation of phospho-STAT-3 and DNA synthesis (as assessed by bromodeoxyuridine labeling), as well as cyclin D1 mRNA induction and protein expression. In contrast, STAT-3 activation was positively correlated with p21 protein expression in both groups of mice. Because these results link exaggerated STAT-3 activation with impaired hepatocyte proliferation, STAT-3 inhibition cannot be a growth-arrest mechanism in ob/ob fatty livers. Rather, hyperinduction of this factor may promote mitoinhibition by up-regulating mechanisms that impede cell cycle progression.     

Chronic inhibition of endoplasmic reticulum stress and inflammation prevents ischaemia-induced vascular pathology in type II diabetic mice

Endoplasmic reticulum (ER) stress and inflammation are important mechanisms that underlie many of the serious consequences of type II diabetes. However, the role of ER stress and inflammation in impaired ischaemia-induced neovascularization in type II diabetes is unknown. We studied ischaemia-induced neovascularization in the hind-limb of 4-week-old db - /db- mice and their controls treated with or without the ER stress inhibitor (tauroursodeoxycholic acid, TUDCA, 150 mg/kg per day) and interleukin-1 receptor antagonist (anakinra, 0.5 μg/mouse per day) for 4 weeks. Blood pressure was similar in all groups of mice. Blood glucose, insulin levels, and body weight were reduced in db - /db- mice treated with TUDCA. Increased cholesterol and reduced adiponectin in db - /db- mice were restored by TUDCA and anakinra treatment. ER stress and inflammation in the ischaemic hind-limb in db - /db- mice were attenuated by TUDCA and anakinra treatment. Ischaemia-induced neovascularization and blood flow recovery were significantly reduced in db - /db- mice compared to control. Interestingly, neovascularization and blood flow recovery were restored in db - /db- mice treated with TUDCA or anakinra compared to non-treated db - /db- mice. TUDCA and anakinra enhanced eNOS-cGMP, VEGFR2, and reduced ERK1/2 MAP-kinase signalling, while endothelial progenitor cell number was similar in all groups of mice. Our findings demonstrate that the inhibition of ER stress and inflammation prevents impaired ischaemia-induced neovascularization in type II diabetic mice. Thus, ER stress and inflammation could be potential targets for a novel therapeutic approach to prevent impaired ischaemia-induced vascular pathology in type II diabetes.     

Effects of estradiol and progesterone on diabetes-associated utero-ovarian atrophy in C57BL/KsJ (db/db) mutant mice

The modulating effects of estradiol (E: 1 microgram/3.5 days) and progesterone (P: 2 mg/3.5 days) on the obesity and hyperinsulinemic and hyperglycemic components of the diabetes-obesity syndrome in female C57BL/KsJ (db/db) mice, which includes cellular atrophy and adiposity in the reproductive tract, were examined and compared to corresponding control (+/?) parameters. All control and diabetic mice received oil (vehicle control), E, or P treatments starting at 4 weeks of age. Body weight, serum insulin levels, blood glucose concentrations, and utero-ovarian lipoprotein lipase activities were analyzed at 8 and 16 weeks of age and related to the ultrastructural changes in the steroid-sensitive uterine epithelium during the treatment period. Neither E nor P had any effect on body weights in (+/?) or (db/db) mice. The pronounced diabetes-associated elevation in serum insulin levels was enhanced by E, and suppressed by P, in 16-week-old (db/db) mice as compared with controls. By 16 weeks of age, the E therapy normalized blood glucose levels in diabetic mice to control levels, whereas P was ineffective in modulating the hyperglycemia. The reduction in blood glucose levels in E-treated diabetic mice correlated temporally with the return of normal intracellular structure including the disappearance of intracellular lipid vacuoles characteristic of uterine epithelium cells of (db/db) mice. The diabetes-induced rise in utero-ovarian lipoprotein lipase activity was normalized by P-therapy. The reduction in utero-ovarian lipoprotein lipase activity coincided temporally with the demonstrated intracellular reorganization in (db/db) reproductive tract tissues.(ABSTRACT TRUNCATED AT 250 WORDS)