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.     

Differential effect of statins on diabetic nephropathy in db/db mice

Recent studies suggest a potential benefit of the lipid-lowering medication in the treatment of chronic kidney disease (CKD) such as diabetic nephropathy. Although statins have been widely used to lower serum cholesterol levels, the effect of these drugs on diabetic nephropathy has not been fully elucidated. In the present study, therefore, we addressed the role of different kinds of statins on diabetic nephropathy in db/db mice. Mice were fed with a standard diet with 0.005% (w/w) of pitavastatin, rosuvastatin, and pravastatin for 8 weeks starting from 8 weeks of age. The treatment with statins did not affect the food intake, body weight gain, adiposity, or blood pressure in db/db mice. Treatment with statins also had no effect on plasma lipid levels. In terms of the effect on albuminuria, pitavastatin and rosuvastatin reduced the urinary excretion of albumin by 60 and 40%, respectively, but not pravastatin, suggesting the effect of these two drugs on diabetic nephropathy. Furthermore, pitavastatin and rosuvastatin improved glomerular hypertrophy. All statins treatment improved insulin resistance. In addition, rosuvastatin and pravastatin treatment reduced oxidative stress measured by urinary 8-OHdG level, whereas the statins had no effect on the inflammatory response in the kidney of db/db mice. These results are not consistent with the renoprotective effect of statins. In conclusion, our data suggest that pitavastatin and rosuvastatin can improve diabetic nephropathy through the suppression of glomerular hypertrophy, independent of lipid-lowering or anti-oxidative effects.     

Increased glomerular and tubular expression of transforming growth factor-beta1, its type II receptor, and activation of the Smad signaling pathway in the db/db mouse

Activation of the renal transforming growth factor-beta (TGF-beta) system likely mediates the excess production of extracellular matrix in the diabetic kidney. To establish the role of the TGF-beta system in type 2 diabetic nephropathy, we examined the intrarenal localization and expression of the TGF-beta1 isoform, the TGF-beta type II receptor, and the Smad signaling pathway in the 16-week-old db/db mouse, a genetic model of type 2 diabetes that exhibits mesangial matrix expansion, glomerular basement membrane thickening, and renal insufficiency that closely resemble the human disease. Compared with its nondiabetic db/m littermate, the db/db mouse showed significantly increased TGF-beta1 mRNA expression by in situ hybridization in both glomerular and tubular compartments. Likewise, TGF-beta1 protein, by immunohistochemical staining, was increased in both renal compartments, but the fractional expression of TGF-beta1 protein was less than that of the mRNA in the glomerulus. In situ hybridization and immunohistochemical staining for the TGF-beta type II receptor revealed concordant and significant increases of both mRNA and protein in the glomerular and tubular compartments of diabetic animals. Finally, immunohistochemistry showed preferential accumulation of Smad3 in the nuclei of glomerular and tubular cells in diabetes. The complementary technique of Southwestern histochemistry using a labeled Smad-binding element demonstrated increased binding of nuclear proteins to Smad-binding element, indicating active signaling downstream of the TGF-beta stimulus. We therefore propose that the TGF-beta system is up-regulated at the ligand, receptor, and signaling levels throughout the renal cortex in this animal model of type 2 diabetes. Our findings suggest that the profibrotic effects of TGF-beta may underlie the progression to glomerulosclerosis and tubulointerstitial fibrosis that characterize diabetic nephropathy.     

db/db自发性糖尿病小鼠睾丸生殖细胞凋亡及相关基因Bcl-2和Bax表达

目的　研究糖尿病时生殖细胞凋亡及相关基因Bcl 2和Bax表达变化。方法　以脱氧核糖核酸末端转移酶介导的dUTP缺口末端标记法 (TUNEL)检测生殖细胞的凋亡 ,免疫组化ABC法检测凋亡相关基因Bcl 2和Bax的表达变化。结果　凋亡管数及凋亡阳性率糖尿病组均较正常高 ,而且随糖尿病病程进展呈明显增加趋势 ,对照组中随加龄二者也有增加。Bcl 2蛋白以散在的颗粒状大量分布于除精原细胞的各级生精细胞中 ,且以精子细胞质为最多。随糖尿病病变加重 ,Bcl 2表达减少 ,而且 ,糖尿病组比对照组Bcl 2表达率低。Bax蛋白比Bcl 2蛋白表达量少 ,以散在的颗粒状分布于曲细精管基底部的精原细胞和支持细胞中。随糖尿病病程进展和年龄增加 ,表达均呈增加趋势 ,而且 ,糖尿病组比对照组Bax表达率高。结论　在db/db自发性糖尿病小鼠睾丸 ,伴随生殖细胞凋亡增加 ,Bcl 2表达减少 ,Bax表达增加 ,凋亡及相关基因在糖尿病生殖功能障碍中起重要作用     

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)     

RAGE drives the development of glomerulosclerosis and implicates podocyte activation in the pathogenesis of diabetic nephropathy

Diabetic nephropathy ensues from events involving earliest changes in the glomeruli and podocytes, followed by accumulation of extracellular matrix in the mesangium. Postulated mechanisms include roles for vascular endothelial growth factor (VEGF), produced by podocytes and contributing to enhanced excretion of urinary albumin and recruitment/activation of inflammatory cells, and transforming growth factor-beta (TGF-beta), elicited largely from mesangial cells and driving production of extracellular matrix. RAGE, a receptor for advanced glycation endproducts (AGEs) and S100/calgranulins, displays enhanced expression in podocytes of genetically diabetic db/db mice by age 13 weeks. RAGE-bearing podocytes express high levels of VEGF by this time, in parallel with enhanced recruitment of mononuclear phagocytes to the glomeruli; events prevented by blockade of RAGE. By age 27 weeks, soluble RAGE-treated db/db mice displayed diminished albuminuria and glomerulosclerosis, and improved renal function. Diabetic homozygous RAGE null mice failed to develop significantly increased mesangial matrix expansion or thickening of the glomerular basement membrane. We propose that activation of RAGE contributes to expression of VEGF and enhanced attraction/activation of inflammatory cells in the diabetic glomerulus, thereby setting the stage for mesangial activation and TGF-beta production; processes which converge to cause albuminuria and glomerulosclerosis.     

The role of interstitial macrophages in nephropathy of type 2 diabetic db/db mice

Diabetic nephropathy is associated with interstitial macrophage infiltrates, but their contribution to disease progression is unclear. We addressed this question by blockade of chemokine receptor (CCR)1 because CCR1 mediates the macrophage recruitment to the renal interstitium. In fact, when CCR1 was blocked with BL5923, a novel orally available CCR1 antagonist, the interstitial recruitment of ex vivo labeled macrophages was markedly decreased in uninephrectomized male db/db mice with advanced diabetic nephropathy. Likewise, BL5923 (60 mg/kg, twice a day) orally administered from months 5 to 6 of life reduced the numbers of interstitial macrophages in uninephrectomized db/db mice. This was associated with reduced numbers of Ki-67 proliferating tubular epithelial and interstitial cells, tubular atrophy, and interstitial fibrosis in uninephrectomized db/db mice. Glomerular pathology and proteinuria were not affected by the CCR1 antagonist. BL5923 reduced renal mRNA expression of Ccl2, Ccr1, Ccr2, Ccr5, transforming growth factor-beta1, and collagen I-alpha1 when compared with untreated uninephrectomized male db/db mice of the same age. Thus, we identified a previously unrecognized role for interstitial macrophages for tubulointerstitial injury, loss of peritubular microvasculature, interstitial inflammation, and fibrosis in type 2 diabetic db/db mice. These data identify oral treatment with the CCR1 antagonist BL5923 as a potential therapy for late-stage diabetic nephropathy.     

Effects of estradiol and raloxifene on arterial thrombosis in ovariectomized mice

OBJECTIVE: The effects of estrogen and selective estrogen receptor modulators (eg, raloxifene) on arterial thrombosis are not well defined. This study assessed the manner and mechanism by which estrogen and raloxifene affect homeostatic pathways in ovariectomized mice after acute arterial injury. DESIGN: Female mice (3 weeks old) underwent ovariectomy or sham operation. Five days after surgery, mice were assigned to treatment with estradiol (5.3 nmol/kg), raloxifene (2.7 micromol/kg), or placebo (n = 10-12/group). The biological effects of both treatments were assessed by measurements of bone mass and the degree of uterine atrophy. After 4 months of therapy, carotid artery thrombosis was induced by photochemical injury, and the time to vascular occlusion was measured. RESULTS: Both treatments increased bone mineral density (4.1%-7.85%). Reversal of macroscopic uterine atrophy was observed only in estrogen-treated mice. Ovariectomized mice had a shorter time to occlusion compared with sham-operated mice (70.8 +/- 7.4 vs 103 +/- 11.3 min), suggesting accelerated thrombosis. Both estradiol and raloxifene significantly inhibited intra-arterial thrombosis in ovariectomized mice, prolonging the time to occlusion to 136.33 +/- 13.5 and 141.43 +/- 9.26 min, respectively. Cyclooxygenase-2 levels in the lung tissue were significantly increased by both raloxifene and estradiol with endothelial nitric oxide synthase expression being unaltered. Platelet adhesion (measured by surface coverage under a shear rate of 1,800 s for 2 min) was significantly reduced in ovariectomized animals, being 4.63% +/- 1.47%, 5.78% +/- 1.58%, and 10.04% +/- 1.33% for raloxifene, estradiol, and placebo, respectively. CONCLUSIONS: Ovariectomy amplifies thrombosis. We found that 4 months of treatment with both estradiol and raloxifene attenuates intravascular thrombosis. The antithrombotic effect was accompanied by increased expression of cyclooxygenase-2 and suppression of platelet surface adhesion.     

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。     

Growth factor midkine is involved in the pathogenesis of diabetic nephropathy

Diabetic nephropathy is a life-threatening disease associated with diabetes mellitus. Longstanding hyperglycemia induces pathological reactions of glomerular mesangial cells, such as overproduction of extracellular matrix, which finally lead to nephropathy. However, the mechanisms underlying its pathogenesis have not been completely elucidated. Using the Streptozotocin-induced model of diabetes, we report that mice deficient in the growth factor midkine (Mdk-/-) exhibited strikingly milder nephropathy than Mdk+/+ mice, even though both mice showed similar extents of hyperglycemia after Streptozotocin injection. Midkine expression was induced in the glomerular mesangium of Mdk+/+ mice with diabetic nephropathy and in primary cultured mesangial cells exposed to high glucose. Mdk-/- mesangial cells exhibited reduced phosphorylation of protein kinase C and extracellular signal-regulated kinase as well as reduced production of transforming growth factor-beta(1) on high glucose loading. Addition of exogenous midkine restored extracellular signal-regulated kinase phosphorylation in Mdk-/- cells under high glucose conditions, whereas a midkine antisense oligodeoxynucleotide suppressed midkine in Mdk+/+ cells. Therefore, this study identifies midkine as a key molecule in diabetic nephropathy and suggests that midkine accelerates the intracellular signaling network evoked by hyperglycemia in nephropathy.     

Late onset of Ccl2 blockade with the Spiegelmer mNOX-E36-3'PEG prevents glomerulosclerosis and improves glomerular filtration rate in db/db mice

Diabetic kidney disease is associated with monocyte chemoattractant CC chemokine ligand 2 (CCL2)-dependent glomerular and interstitial macrophage recruitment. In addition, nephropathy is delayed in Ccl2 mutant diabetic mice. However, whether the late onset of therapeutic Ccl2 blockade modulates the progression of advanced diabetic nephropathy remains unknown. We addressed this question by antagonizing Ccl2 with mNOX-E36-3'PEG, an anti-Ccl2 L-enantiomeric RNA aptamer (ie, a Spiegelmer), which binds murine Ccl2 and blocks the recruitment of ex vivo-labeled macrophages to the kidneys of db/db mice with type 2 diabetes. We injected mNOX-E36-3'PEG subcutaneously at a dose of 50 mg/kg three times per week into uninephrectomized (1K) db/db mice with advanced glomerulopathy from 4 to 6 months of age. mNOX-E36-3'PEG reduced the number of glomerular macrophages by 40% compared with nonfunctional (control) Spiegelmer-treated 1K db/db mice. This result was associated with protection from diffuse glomerulosclerosis and significantly improved the glomerular filtration rate. mNOX-E36-3'PEG also reduced renal Ccl2 mRNA and protein expression compared with control Spiegelmer-treated 1K db/db mice of the same age. Together, the late onset of therapeutic Ccl2 blockade, eg, with specific Spiegelmers, offers protection from diffuse glomerulosclerosis in type 2 diabetic db/db mice and, thus, may represent a novel therapeutic strategy for advanced glomerulosclerosis.     

Hepatic metabolism of genetically diabetic (db/db) mice. I. Carbohydrate metabolism.

Hepatic carbohydrate metabolism in genetically diabetic mice (db/db) and their normal littermates has been studied. In db/db mice, body water was below normal and declined with age. The liver of db/db mice was abnormally large in relation to the metabolic mass of the body at all ages studied. In db/db mice, hepatic glycogenolysis, glycogen synthesis, glycogen synthetase, and phosphorylase were markedly increased. Gluconeogenesis from alanine or lactate in perfused livers of db/db mice was greater than normal per 100 g body water. Activities of fructose-1, 6-biophosphatase, glucose-6-phosphatase, glucokinase + hexokinase, and pyruvate kinase were elevated in livers of db/db mice. Diabetic mouse livers perfused with lactate showed a markedly reduced concentration of P-enolpyruvate and clear "forward crossover" between fructose-1, 6-P2 and fructose-6-P. In vivo glucose clearance, measured with [3-3H]glucose, in db/db mice was 170% that of normal mice. Data presented indicate that in livers of db/db mice: 1) glucose production is elevated prior to hyperglycemia, 2) glycogen turns over more rapidly, and 3) glycolytic and gluconeogenic enzymes are elevated paradoxically. These abnormalities are discussed from the viewpoint of their etiology.     

Ramipril improves oxidative stress-related vascular endothelial dysfunction in db/db mice

Endothelial dysfunction often precedes Type 2 diabetes-associated cardiovascular complications. One important cause of endothelial dysfunction is oxidative stress, which can lead to reduced nitric oxide (NO) bioavailability. In this study, we examined the effects of ramipril (an angiotensin-converting enzyme inhibitor, ACEI) on reactive oxygen species (ROS) production and endothelium-dependent vasodilation using a Type 2 diabetic (db/db) murine model. Plasma concentration of 8-isoprostane ([8-isoP]) was measured and used as an indication of the amount of ROS production. Six weeks of ramipril (10 mg/kg/day) treatment significantly reduced [8-isoP] and improved acetylcholine(ACh)-induced vasodilation in db/db mice without altering responses in wild-type (WT) mice. Responsiveness of smooth muscle cells to NO, assessed by sodium nitroprusside-induced vasodilation, was not different between db/db and WT mice regardless of ramipril or vehicle treatment. Our results suggest that ramipril specifically improved endothelium-dependent vasodilation in Type 2 diabetic mice, possibly by reducing ROS levels.     

db/db自发性糖尿病小鼠睾丸生殖细胞增殖及凋亡研究

目的　研究糖尿病对生殖细胞增殖和凋亡的影响。　方法　以免疫组织化学ABC法检测增殖细胞核抗原 (proliferationcellnucleusantigen ,PCNA)检测生殖细胞的增殖情况 ,电镜和脱氧核糖核酸末端转移酶介导的dUTP缺口末端标记法 (TUNEL)检测凋亡的生殖细胞。　结果　PCNA阳性率随糖尿病病程进展 (糖尿病组 )和年龄增加 (对照组 )均呈明显下降趋势 ,但每年龄段糖尿病组PCNA阳性率均明显低于相应正常对照组。凋亡管横断面数及凋亡阳性率糖尿病组均较正常高 ,而且随糖尿病病程进展呈明显增加趋势 ,对照组中随加龄二者有增加。电镜下 ,糖尿病组小鼠睾丸精原细胞、精母细胞和精子细胞均可见到核染色质凝集、边集 ,凋亡小体形成和降解等凋亡过程。　结论　db/db自发性糖尿病小鼠睾丸生殖细胞PCNA表达减弱 ,TUNEL标记凋亡细胞增加 ,说明糖尿病使生殖细胞增殖与凋亡的平衡破坏 ,这可能是糖尿病生殖功能障碍的原因     

Gender-dependent attenuation of cardiac potassium currents in type 2 diabetic db/db mice

Single ventricular myocytes were prepared from control db /+ and insulin-resistant diabetic db/db male mice at 6 and 12 weeks of age. Peak and sustained outward potassium currents were measured using whole-cell voltage clamp methods. At 6 weeks currents were fully developed in control and diabetic mice, with no differences in the density of either current. By 12 weeks both currents were significantly attenuated in the diabetic mice, but could be augmented by in vitro incubation with the angiotensin-converting enzyme (ACE) inhibitor quinapril (1 μ m , 5–9 h). In cells from female db/db mice (12 weeks of age), K⁺ currents were not attenuated and no effects of quinapril were observed. To investigate whether lack of insulin action accounts for these gender differences, cells were also isolated from cardiomyocte-specific insulin receptor knockout (CIRKO) mice. Both K⁺ currents were significantly attenuated in cells from male and female CIRKO mice, and action potentials were significantly prolonged. Incubation with quinapril did not augment K⁺ currents. Our results demonstrate that type 2 diabetes is associated with gender-selective attenuation of K⁺ currents in cardiomyocytes, which may underlie gender differences in the development of some cardiac arrhythmias. The mechanism for attenuation of K⁺ currents in cells from male mice is due, at least in part, to an autocrine effect resulting from activation of a cardiac renin–angiotensin system. Insulin is not involved in these gender differences, since the absence of insulin action in CIRKO mice diminishes K⁺ currents in cells from both males and females.     

Feeding, activity, and body temperature following 6-hydroxydopamine lesions in diabetes (db/db) mice

Reductions in central catecholamines produced by intraventricular injections of 6-hydroxydopamine (6-OHDA) cause weight loss and decreased plasma glucose in diabetes (db/db) mice. The effects of this treatment were examined in short-term (64-day) and long-term (120-day) survival groups. Diabetes mice treated with 6-OHDA decreased food intake, lost weight, and maintained a lower weight than vehicle-treated controls until vehicle-treated animals began to enter the terminal stages of the syndrome, indicated by a loss of body weight. Diabetes mice given 6-OHDA lost weight despite reduced body temperatures and activity levels. Blood glucose levels were always lower in 6-OHDA than in ad lib fed vehicle-treated db/db mice. The 6-OHDA treatment also improved pancreatic islet granulation. Pair feeding vehicle-treated with 6-OHDA-treated db/db mice did not halt weight gain in the vehicle-treated group. However, measurement of carcass fat indicated similar losses in db/db-6-OHDA mice and vehicle-treated mice when the vehicle group was pair-fed with lean controls. Treatment with 6-OHDA produced long-term improvement in the diabetes syndrome, but the decreased body weight of the 6-OHDA-treated diabetes mice could not be completely accounted for by changes in food intake or measured indices of energy expenditure.     

保护素D1 通过抑制肾脏炎症及足突细胞上皮-间充质转化而抑制早期 糖尿病肾病小鼠肾纤维化

 目的：保护素D1 (PD1) 是一个潜在的抗炎症脂蛋白分子,本实验探讨其治疗早期糖尿病肾病（DN）肾纤维化的作用及机制。方法：用链脲佐菌素125 mg/kg 2次腹腔注射C57BL/6J雌性小鼠,建立早期DN小鼠模型。糖尿病模型成功后,用PD1（0.08 mg·kg-1·d-1）腹腔注射治疗,设正常鼠及DN鼠为对照。治疗8周后检测各组小鼠24 h尿蛋白及尿白蛋白定量、体重、肾重、肾重/体重比、血清及尿肌酐和肌酐清除率;用PAS染色法检测肾小球系膜区基质/肾小球面积比,用免疫荧光染色法检测肾皮质中巨噬细胞的数量,用Western blotting检测肾小球纤连蛋白（FN）和α-平滑肌肌动蛋白（α-SMA）的表达,以及肾小球足突细胞特异性上皮标志蛋白zonula occludens-1(ZO-1)和P-cadherin的表达;同时,体外用高糖刺激小鼠巨噬细胞株RAW264.7,检测PD1对其分泌肿瘤坏死因子α（TNF-α）和白细胞介素1β（IL-1β）的抑制作用。体外用转化生长因子β1（TGF-β1）刺激小鼠足突细胞株,用Western blotting检测PD1对其诱导足突细胞上皮-间充质转化(EMT)中上皮细胞标志蛋白P-cadherin 和ZO-1减少的恢复作用,及间充质细胞标志蛋白成纤维细胞特异性蛋白1（FSP1） 和α-SMA过表达的抑制作用。结果：PD1能减少DN小鼠肾小球系膜基质的积聚、24 h尿蛋白及尿白蛋白定量、体重、肾重和肾重/体重比,抑制异常增高的肌酐清除率。PD1能减少DN小鼠肾皮质中巨噬细胞的数量,抑制DN小鼠肾小球FN和α-SMA的表达,恢复足突细胞特异性上皮标志蛋白ZO-1和P-cadherin的表达。PD1能抑制高糖诱导RAW264.7分泌TNF-α和IL-1β,能抑制TGF-β1诱导足突细胞FSP1和α-SMA表达的增加以及ZO-1和P-cadherin表达的减少。结论：PD1能减轻早期DN小鼠肾纤维化,其部分机制可能通过抑制肾脏的炎症及足突细胞EMT。     

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.     

Blockade of TSP1-dependent TGF-β activity reduces renal injury and proteinuria in a murine model of diabetic nephropathy

Transforming growth factor-β (TGF-β) is key in the pathogenesis of diabetic nephropathy. Thrombospondin 1 (TSP1) expression is increased in diabetes, and TSP1 regulates latent TGF-β activation in vitro and in diabetic animal models. Herein, we investigate the effect of blockade of TSP1-dependent TGF-β activation on progression of renal disease in a mouse model of type 1 diabetes (C57BL/6J-Ins2(Akita)) as a targeted treatment for diabetic nephropathy. Akita and control C57BL/6 mice who underwent uninephrectomy received 15 weeks of thrice-weekly i.p. treatment with 3 or 30 mg/kg LSKL peptide, control SLLK peptide, or saline. The effects of systemic LSKL peptide on dermal wound healing was assessed in type 2 diabetic mice (db/db). Proteinuria (urinary albumin level and albumin/creatinine ratio) was significantly improved in Akita mice treated with 30 mg/kg LSKL peptide. LSKL treatment reduced urinary TGF-β activity and renal phospho-Smad2/3 levels and improved markers of tubulointerstitial injury (fibronectin) and podocytes (nephrin). However, LSKL did not alter glomerulosclerosis or glomerular structure. LSKL did not increase tumor incidence or inflammation or impair diabetic wound healing. These data suggest that selective targeting of excessive TGF-β activity through blockade of TSP1-dependent TGF-β activation represents a therapeutic strategy for treating diabetic nephropathy that preserves the homeostatic functions of TGF-β.     

The effects of diethyldithiocarbamate,a SOD inhibitor,on endothelial function in sedentary and exercised db/db mice

The study was designed to evaluate the effects of diethyldithiocarbamate (DDC), an superoxide dismutase (SOD) blocker on endothelial function in db/db mice. The db/db and wild-type (WT) mice were randomly divided into low intensity exercise, moderate intensity exercise and control (sedentary) groups. Mice were exercised daily, 5 days per week. After 6 weeks, ring segments of aortae were mounted in wire myograph and acetylcholine (ACh) concentration response curves were recorded in absence or presence of DDC and DDC plus SOD.Results showed that ACh concentration response curve was similar in WT and WT exercised groups. Incubation of aorta rings of WT mice with DDC suppressed the maximum ACh response (p < 0.05). Subsequent incubation with SOD restored vasodilatory response in WT mice. The vasodilatation to ACh was significantly reduced in sedentary db/db mice compare to WT (p < 0.05) and incubation with DDC did not further decrease this response, however, addition of SOD restored the vasodilatation to ACh to that observed in WT mice. Mild and moderate exercised db/db mice had ACh response similar to that in WT mice. Incubation with DDC incubation reduced ACh induced vasodilatation and addition of SOD restored this response.Our results support the conclusion that SOD mimetics can be used to improve superoxide-mediated endothelial dysfunction in diabetic db/db mice.