PPAR-gamma agonist protects podocytes from injury

Podocyte injury and loss contribute to progressive glomerulosclerosis. Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is a nuclear hormone receptor, which we have found to be increased in podocytes in a variety of kidney diseases. It is not known if PPAR-gamma contributes to renal injury or if it serves as a countermeasure to limit renal injury during disease progression. We tested these possibilities utilizing the puromycin aminonucleoside (PAN) model of renal injury in immortalized mouse podocytes. The cultured podocytes expressed PPAR-gamma mRNA at baseline but this was decreased by PAN. Pioglitazone, a pharmacologic agonist of PPAR-gamma, increased both PPAR-gamma mRNA and activity in injured podocytes, as assessed by a reporter plasmid assay. Further, pioglitazone significantly decreased PAN-induced podocyte apoptosis and necrosis while restoring podocyte differentiation. The PPAR-gamma agonist significantly restored expression of the cyclin-dependent kinase inhibitor p27 and the antiapoptotic molecule Bcl-xL while significantly decreasing proapoptotic caspase-3 activity. Pioglitazone tended to decrease PAN-induced transforming growth factor-beta (TGF-beta) mRNA expression. Our study shows that PPAR-gamma is normally expressed by podocytes and its activation is protective against PAN-induced apoptosis and necrosis. We postulate that this protective effect may be mediated in part by effects on p27 and TGF-beta expression.     

Induction of antioxidant enzymes in murine podocytes precedes injury by puromycin aminonucleoside

BACKGROUND: An imbalance between the generation of reactive oxygen species (ROS) and antioxidant defense mechanisms has been suggested to play an important role in podocyte injury in nephrotic syndrome. Experimental nephrotic syndrome induced by injection of puromycin aminonucleoside (PAN) into rats is a well-established model of nephrotic syndrome, and can be largely prevented by pretreatment with antioxidant enzymes (AOE), suggesting that podocyte injury may be mediated by ROS. METHODS: To test the hypothesis that PAN-induced podocyte injury is modulated in part by podocyte antioxidant defenses, we analyzed AOE activities, lipid peroxidation products, and relative ROS levels in podocytes using our recently reported in vitro model of PAN-induced podocyte injury. RESULTS: PAN treatment induced early increases in both podocyte hydrogen peroxide and superoxide and later increases in lipid peroxidation products. Compared to baseline activities, PAN also induced significant changes in the major cellular AOE activities (maximum increases of 151% for catalase, 134% for superoxide dismutase, and 220% for glutathione peroxidase vs. time-matched controls). These changes largely preceded the development of extensive podocyte process retraction and actin filament disruption, which was maximal at 7 days. CONCLUSION: These results demonstrate that (1) PAN treatment induces significant early changes in podocyte ROS, (2) podocytes can mount an antioxidant defense against oxidant stress, and (3) this protective response is initiated prior to the development of extensive oxidant-induced podocyte structural injury. These findings suggest that enhancement of podocyte AOE activities represent a potential therapeutic target to protect from or ameliorate podocyte injury during nephrotic syndrome.     

1,25(OH)2D3抑制嘌呤霉素氨基核苷酸肾病大鼠足细胞凋亡

目的 观察1，25（OH）2D3对嘌呤霉素氨基核苷酸（PAN）肾病大鼠足细胞凋亡的影响。 方法 72只雄性SD大鼠随机分为健康对照组（NC）、PAN组和1，25（OH）2D3治疗组 [1，25（OH）2D3 0.2 μg·kg-1·d-1灌胃]。一次性尾静脉注射PAN 100 mg/kg体质量建立足细胞损伤的PAN肾病动物模型。于3、7、14、21 d分批处死动物，分别检测不同时间点尿蛋白量（24 h）和肾功能。光镜和透射电镜观察肾组织学改变。TUNEL法检测足细胞凋亡。RT-PCR、免疫荧光、免疫组化分别检测nephrin、TGF-β1 mRNA和蛋白的表达。Western印迹检测磷酸化（p）-Smad2/3的表达。 结果 （1）PAN组各时间点BUN、Scr、尿蛋白量（24 h）[7 d时，（20.26±4.87） mg比（1.01±0.41） mg，P < 0.01]均高于同期的NC组，而肾小球足细胞显著减少[14 d时，(10.9±4.2) 个/肾小球切面比(31.9±6.2)个/肾小球切面，P ＜ 0.01]，且足突增宽融合。1，25（OH）2D3治疗组各时间点尿蛋白量（24 h）[7 d时（9.95±3.82） mg]和BUN、Scr显著低于PAN组（P < 0.05），且肾脏病理改变减轻。（2）PAN组7 d时nephrin mRNA和蛋白的表达显著降低，nephrin由正常的沿毛细血管襻线状分布向颗粒状、团快状改变，足细胞凋亡数显著增加[14 d时，（37.4±7.9）个/肾小球切面]。与PAN组相比，1，25（OH）2D3治疗组各时间段nephrin mRNA和蛋白的表达显著增加，且保持着正常的沿毛细血管襻线状分布，足细胞凋亡数显著减少[14 d时，(21.9±6.2) 个/肾小球切面，P < 0.01]。（3）PAN组TGF-β1 mRNA和蛋白的表达以及p-Smad2/3蛋白的表达均高于NC组（P < 0.01），1，25（OH）2D3治疗组TGF-β1 mRNA和蛋白的表达以及p-Smad2/3蛋白的表达低于PAN组（P < 0.01）。 结论 1，25（OH）2D3能有效地抑制PAN诱导的足细胞凋亡，减少尿蛋白，其对足细胞损伤的保护作用可能与抑制TGF-β1信号通路有关。     

cAMP/PKA signal activation prevents chemical-induced podocyte injury

Objective To investigate the role of activated cylic AMP(cAMP) signaling in chemical-induced podocyte injury. Methods Eight-weeks-old male BalB/C mice were randomly divided into three groups: control group, Adriamycin (ADR) group and Forskolin+ADR group. ADR nephropathy models were established by tail intravenous injection,and part of them were injected Forskolin, an agonist of adenylate cyclase, intraperitoneally. Phosphorylation of cAMP response element binding protein (CREB) was detected by laser confocal microscopy,morphology of foot processes were determined with transmission electron microscope, and WT-1 expression in glomeruli were detected by immunohistochemistry. Conditionally immortalized podocytes were treated with puromycin aminonucleoside (PAN), Exchange protein directly activated by cAMP (Epac) agonist 8-pCPT-2-O-Me-cAMP (2Me),protein kinase A (PKA) antagonist H89 and its agonist pCPT-cAMP(pCPT). Western blot was used to detect the expression levels of Epac, caspase3 and cleaved caspase3. PKA activity was assayed using cAMP-dependent protein kinase detection system. Cell viability was determined by a cell count kit and podocyte apoptosis was estimated by TUNEL staining. Mitochondrial membrane potential was evaluated by JC-1 staining. Results （1）Compared with ADR group, the urine albumin decreased significantly (P＜0.05) among Forskolin+ADR group and the WT-1 positive cells per glomerulus increased obviously (P＜0.05). （2）PAN decreased podocyte number in a time-dependent manner (P＜0.05), pre-treatment with pCPT obviously inhibited PAN induced podocyte decrease (P＜0.05), but H89 prevented the effect of pCPT in a dose-dependent manner (P＜0.05). （3）JC-1 staining showed that the percentage of podocyte with green fluorescence for control, PAN and pCPT+PAN group were (12.67±2.15)%, (31.35±4.60)% and (16.96 ± 2.51)%respectively (P＜0.05), and pretreatment with H89 inhibited the effect of pCPT (P＜0.05). （4）PAN promoted podocyte apoptosis and cleaved caspase3 expression (P＜0.05), and pretreatment with pCPT significantly prevented PAN-induced podocyte apoptosis and cleaved caspase3 expression (P＜0.05). Conclusions cAMP signaling activation ameliorated podocyte injury in ADR mice and PAN-induced podocyte apoptosis, and cAMP/PKA pathway may mediate these processes.     

Fluvastatin attenuates the down?regulation of β1 integrin expression in PAN?treated podocytes by inhibiting ROS

Objective To investigate the effect of fluvastatin（FLV）on the expression of β1 integrin in puromycin aminonucleoside (PAN)?treated podocytes and its mechanism. Methods Cultured human podocytes were divided into PAN, different concentrations of fluvastatin（1×10-8 to 1×10-5 mol/L）,SOD, H2O2 groups respectively. Expressions of β1 integrin and reactive oxygen species (ROS) in podocytes were detected by Western blotting and DCFHDA (2’7’?Dichlorofluoresecein 3’6’?diacetate) respectively. The viability of podocyte was determined by MTT colorimetry. Results PAN and H2O2 significantly decreased the expression of β1 integrin and increased the synthesis of ROS in podocytes (P<0.05 respectively). Lower concentration fluvastatin or SOD treatment up?regulated β1 integrin and down?regulated ROS of podocytes induced by PAN (P<0.05 respectively). MTT revealed that lower podocyte viability was found in higher concentration fluvastatin, PAN and H2O2 groups. Lower concentration fluvastatin and SOD could protect podocytes against PAN. Conclusion Fluvastatin attenuates the injury of podocyte induced by PAN and increases the expression of β1 integrin, whose mechanism may be associated with the inhibition of the ROS activity.     

Fluvastatin ameliorates podocyte injury in proteinuric rats via modulation of excessive Rho signaling

Statins have been reported to confer renoprotection in several experimental models of renal disease through pleiotropic actions. The roles of statins in glomerular podocytes have not been explored. The objective of this study was to evaluate the effects of fluvastatin on podocyte and tubulointerstitial injury in puromycin aminonucleoside (PAN)-induced nephrosis. PAN induced massive proteinuria and serum creatinine elevation on day 7, which were significantly suppressed by fluvastatin. Immunofluorescence studies of podocyte-associated proteins nephrin and podocin revealed diminished and discontinuous staining patterns in rats with PAN nephrosis, indicating severe podocyte injury. Fluvastatin treatment dramatically mitigated the abnormal staining profiles. Reduction of nephrin expression by PAN and its reversal by fluvastatin were confirmed by quantitative analyses. By electron microscopy, effacement of foot processes was ameliorated in fluvastatin-treated rats. Fluvastatin also mitigated tubulointerstitial damage in PAN nephrosis, with the repression of PAN-induced NF-kappaB and activator protein-1 activation in the kidneys. In addition, expression of activated membrane-bound small GTPase RhoA was markedly increased in the glomeruli of PAN nephrosis, which was inhibited by fluvastatin treatment. In cultured podocytes, fluvastatin suppressed PAN-evoked activation of RhoA and actin cytoskeletal reorganization. Furthermore, fasudil, a specific Rho-kinase inhibitor, successfully ameliorated PAN-induced podocyte damage and proteinuria. In summary, fluvastatin alleviated podocyte and tubulointerstitial injury in PAN nephrosis. The beneficial effects of fluvastatin on podocytes can be attributable to direct modulation of excessive RhoA activity. Our data suggest a therapeutic role for statins in clinical conditions that are relevant to podocyte injury.     

Salvia przewalskii extract of total phenolic acids inhibit TLR4 signaling activation in podocyte injury induced by puromycin aminonucleoside in vitro

Background: TLR4 signaling is known to be involved in podocyte injury. We have previously shown that Salvia przewalskii extract of total phenolic acids (SPE) and its active monomer salvianolic acid B (SalB) and rosmarinic acid (RA) protect podocytes from injury induced by PAN. In the present study, we test whether SPE inhibits TLR4 signaling.

Methods: The conditionally immortalized mouse podocytes were treated with SPE, SalB, RA, SalB?+?RA or tacrolimus for 30?min, followed by PAN (100?μg/mL) for 24?h. The F-actin staining with phalloidin was used to assess cytoskeletal injury in the podocytes. Western blotting and semi-quantitatives RT-PCR were used to assess the changes of the components in the TLR4 signaling pathway.

Results: (1) The F-actin stress fibers of podocytes were almost completely disrupted after PAN treatment for 24?h, and the disruption was significantly alleviated by SPE; (2) the PAN-induced elevation of mRNA levels of TLR4, MyD88 and p65 were inhibited except p65 with high-dose SalB; (3) consistently, the protein levels of TLR4, MyD88 and pp65 were significantly elevated by PAN, and SPE, SalB, RA and admixture, respectively, attenuated the elevations of TLR4 and pp65 proteins; (4) SPE and tacrolimus have a similarly strong effect on inhibition of the expression of TLR4 signaling components.

Conclusions: SPE protects podocytes from PAN-induced injury at least partly through inhibiting TLR4 signaling. SPE is as strong as tacrolimus in inhibiting TLR4 signaling in podocytes.     

AGE与RAGE相互作用通过活性氧引起足细胞凋亡

目的：探讨晚期糖基化终末产物（AGE）对足细胞凋亡的影响,及氧化应激在其中的作用。方法：小鼠足细胞株由美国纽约西奈山医学院Peter Mundel教授馈赠。用钙磷脂结合蛋白Ⅴ-荧光异硫氰酸盐（FITC）和碘化物（PI）标记细胞,采用荧光激活细胞分类（FACS）法来计数凋亡和坏死的足细胞。Dharmacon On TargetPlus SMARTpool si RNA试剂和Amaxa RNAi nucleofection试剂盒成功转染si RNA到足细胞。绿荧光蛋白载体证明转染的有效性,分别采用Western Blot和实时定量PCR（RT-PCR）方法来检测si RNA转染足细胞后AGE受体蛋白（RAGE）靶基因蛋白质和mRNA的表达。用LS50B型荧光分光光度计测活性氧,根据波长485nm在530nm发射的荧光来判断活性氧（ROS）的产生。观察活性氧的清除剂N-乙酰基-半胱氨酸（NAC）能否减少AGE-BSA诱导的足细胞凋亡。结果：AGE引起足细胞的凋亡呈剂量依赖性,随AGE浓度的增大,凋亡的发生率逐渐升高;RAGE siRNA能减少60%~70%RAGE mRNA和蛋白质的表达;ROS的清除剂NAC可明显减少AGE-BSA引起的ROS的产生和足细胞凋亡。结论：AGE与RAGE作用后活性氧产生增加,活性氧的增加可能是AGE引起足细胞凋亡的途径之一,可通过抗氧化减少ROS的产生延缓糖尿病肾病的进展。     

活性氧介导醛固酮诱导的足细胞凋亡

目的 观察醛固酮（ALD）及其受体拮抗剂螺内酯（SPI）对足细胞活性氧（ROS）产生及凋亡的影响,并探讨其可能机制。 方法 体外培养条件的永生化小鼠足细胞系,分为空白对照组、ALD组、SPI组、ALD+SPI组;用荧光分光光度计检测足细胞内ROS水平;间接免疫荧光检测nephrin表达;流式细胞仪检测足细胞凋亡率;RT-PCR、Western 印迹法检测bax、bcl-2 mRNA及蛋白表达。同时观察抗氧化剂N-乙酰半胱氨酸（NAC）对上述效应的阻断作用。 结果 与对照组相比,ALD诱导足细胞ROS产生增多（P < 0.05）,该作用可被SPI阻断（P < 0.05）。ALD可诱导足细胞nephrin表达降低及足细胞凋亡（P < 0.05）,同时伴有bax mRNA、蛋白表达升高及bcl-2 mRNA、蛋白表达降低（P < 0.05）,SPI及NAC可阻断这一变化（P < 0.05）。 结论 ALD通过ROS途径作用于盐皮质激素受体上调促凋亡因子bax表达,下调抑凋亡因子bcl-2表达,进而诱导足细胞凋亡。     

The role of adrenomedullin and receptors in glomerular hyperfiltration in streptozotocin-induced diabetic rats

BACKGROUND: Since adrenomedullin (AM) elicits vasodilatation by binding to specific AM receptors consisted of calcitonin-receptor-like receptor (CRLR)/receptor-activity-modifying protein 2 (RAMP2) or CRLR/receptor-activity-modifying protein 3 (RAMP3) on endothelial cells and stimulating nitric oxide production, AM possibly involves in glomerular capillary dilatation in early phase of diabetic nephropathy. METHODS: Streptozotocin (STZ)-induced diabetic Sprague-Dawley rats at 4 weeks after the injection were employed for expression studies of AM, RAPM2, and RAMP3. The measurement of AM peptide levels in kidney tissue, plasma, and urine was performed. Human aortic endothelial cells (HAEC) were used to investigate functional link between glucose-induced AM production and nitric oxide release. RESULTS: STZ rats showed glomerular hypertrophy and increased urinary NO2- and NO3- excretion. By Northern blot analyses, AM and RAPM2 mRNAs significantly increased in the kidneys of STZ rats, while RAMP3 mRNA was not altered. In STZ rats, AM peptide was actively secreted into urine (1280 +/- 360 fmol/day vs. control 110 +/- 36 fmol/day). AM peptide was mainly detected on cortical and medullary collecting duct cells in control rat kidneys and AM peptide and mRNA were up-regulated on afferent arterioles and glomeruli of STZ rats. RAMP2 expression was detected on afferent arterioles and not in glomeruli in control rats and it was up-regulated on glomerular endothelial cells in STZ rats. In HAEC culture, d-glucose stimulated AM and nitric oxide production and they were suppressed by addition of AM antisense oligodeoxynucleotides. CONCLUSION: Up-regulated expression of AM and RAMP2 in afferent arterioles and glomeruli may be related to selective dilatation of glomerular capillary in acute phase of type 1 diabetes.     

Evidence suggesting a role for hydroxyl radical in puromycin aminonucleoside-induced proteinuria

A single intravenous injection of puromycin aminonucleoside (PAN) results in marked proteinuria and glomerular morphological changes that are similar to minimal change disease in humans. We examined the effect of hydroxyl radical scavengers and an iron chelator on PAN-induced proteinuria. PAN in a dose of 5 mg/100 g body wt significantly increased urinary protein by day 5 (saline: 15 +/- 2, N = 24: PAN: 63 +/- 17, N = 23, P less than 0.001); the proteinuria rapidly increased thereafter, reaching 216 +/- 34, N = 23 by day 7. Concurrent administration of hydroxyl radical scavengers dimethylthiourea, (DMTU 500 mg/kg followed by 125 mg/kg i.p. twice a day) and sodium benzoate (BENZ, 150 mg/kg followed by 125 mg/kg i.p. twice a day) starting the evening before PAN injection markedly reduced proteinuria throughout the course of the study (urinary protein, mg/24 hours on day 7, mean +/- SEM: PAN: 229 +/- 45, N = 15; PAN + DMTU: 30 +/- 5, N = 18; PAN + BENZ: 80 +/- 18, N = 16. Because of the participation of iron in biological systems to generate hydroxyl radical, we also examined the effect of deferoxamine (DFO, 30 mg/day), an iron chelator, on the PAN-induced proteinuria. Concurrent administration of DFO was also protective. In a second series of experiments, DMTU and DFO (administered as described above and then for two additional days after the PAN) provided marked protection even when they were stopped prior to the onset of proteinuria. The protective effects of two hydroxyl radical scavengers and iron chelator implicate an important role for hydroxyl radical in PAN-induced nephrotic syndrome.     

IGF-1 protects intestinal epithelial cells from oxidative stress-induced apoptosis

BACKGROUND: Reactive oxygen species (ROS) are involved in the pathogenesis of necrotizing enterocolitis (NEC) in premature infants. We have recently found that activation of multiple cellular signaling transduction pathways occurs during ROS-induced intestinal cell apoptosis; the phosphatidylinositol 3-kinase (PI3-K) pathway plays an anti-apoptotic role during this process. Insulin-like growth factor (IGF)-1 activates PI3-K pathway to promote cell survival; however, the effects of IGF-1 treatment during gut injury are not clearly defined. The purpose of this study was to determine whether IGF-1 protects intestinal cells from ROS-induced apoptosis. MATERIALS AND METHODS: Rat intestinal epithelial (RIE)-1 cells were treated with either IGF-1 (100 nm), hydrogen peroxide (H2O2; 500 microm), or combination. Western blotting was performed to assess phosphorylation of Akt, a downstream effector of PI3-K. Cell Death Detection ELISA, DCHF, and JC-1 assays were performed to demonstrate protective effects of IGF-1. Wortmannin, an inhibitor of PI3-K, was used to show PI3-K-dependent mechanism of action for IGF-1. RESULTS: H2O2 treatment resulted in increased intestinal epithelial cell apoptosis with intracellular ROS generation and mitochondrial membrane depolarization; IGF-1 pre-treatment attenuated this response without affecting ROS production. H2O2-induced phosphorylation of Akt was further increased with IGF-1 treatment; wortmannin abolished these effects in RIE-1 cells. CONCLUSIONS: PI3-K pathway is activated during ROS-induced intestinal epithelial cell injury; IGF-1 exerted an anti-apoptotic effect during this response by PI3-K activation. A better understanding of the exact role of IGF-1-mediated activation of PI3-K may allow us to facilitate the development of novel therapy against NEC.     

敲低CD2相关蛋白的表达对足细胞黏附和胞质伸展功能的影响

目的 观察敲低足细胞CD2相关蛋白（CD2AP）表达对细胞黏附和胞质伸展功能的影响，并探讨其机制。 方法 用RPMI 1640培养基33℃下培养小鼠未分化足细胞系，转染针对CD2AP的小分子干扰RNA（siRNA），设无特异靶位点的scrambing 序列即control siRNA转染组作对照。48 h后将转染的足细胞制备成单细胞悬液，接种于预铺有Ⅳ型胶原蛋白的96孔板内，33℃下培养90 min后检测足细胞的贴壁率和细胞的伸展面积；流式细胞仪检测抑制CD2AP后足细胞的凋亡率以及在不同氨基核苷嘌呤霉素（PAN）刺激下足细胞的凋亡率；激光共聚焦显微镜下检测F肌动蛋白（F-actin）的分布变化；Western印迹和免疫共沉淀检测nephrin蛋白的表达及其磷酸化水平。 结果 转染CD2AP siRNA足细胞的黏附率为41.72%±6.07%，显著低于对照组64.46%±8.53%（P < 0.05）；细胞伸展的面积>200 μm2的比例（55.86％）亦显著低于对照组（73.61％）。转染CD2AP siRNA后48 h足细胞的凋亡率高于对照组[（5.73±0.61）％比（3.26±0.45）％，P < 0.05]。100 mg/L的PAN能明显诱导足细胞的凋亡，减少足细胞的黏附率（P < 0.05）。敲低CD2AP的表达后足细胞F-actin的分布发生明显的变化，nephrin蛋白表达和磷酸化水平下降（P < 0.05）。 结论 敲低CD2AP的表达使足细胞易于凋亡，影响细胞的黏附功能。足细胞骨架蛋白的紊乱和nephrin信号通路的抑制可能是足细胞黏附和伸展功能下降的机制。     

Antioxidants ameliorate the expression of vascular endothelial growth factor mediated by protein kinase C in diabetic podocytes.

BACKGROUND: The increased production of reactive oxygen species (ROS) may be involved in the onset or development of diabetic vascular complications. The release of ROS from podocytes plays a role in the pathogenesis of glomerular damage in various experimental glomerular diseases. Although it is assumed that the podocyte injury also plays an important role in diabetic nephropathy, the mechanism is still unknown. METHODS: Using a differentiated mouse podocyte cell line, we investigated: (1) whether a high level of ambient glucose increases the level of ROS, (2) whether the protein kinase C (PKC) pathway is involved in a high-glucose-induced generation of ROS and vascular endothelial growth factor (VEGF) and (3) whether antioxidants ameliorate PKC-mediated VEGF expression in diabetic milieu. RESULTS: Intracellular ROS generation was significantly higher in high glucose than in control conditions in cultured podocytes. High ambient glucose also increased VEGF mRNA and protein expression. The high-glucose-induced increases in ROS and VEGF mRNA and protein by podocytes were effectively inhibited by pretreatment with various antioxidants and were completely restored by PKC inhibition. The results show that cultured mouse podocytes produce ROS in response to high glucose, and that PKC is involved in high-glucose-induced ROS and VEGF production by podocyte. CONCLUSION: Increased ROS in podocytes may play a role in the pathogenesis of podocyte injury in diabetic nephropathy.     

Influence of dexamethasone on the expression and distribution of transient receptor potential cation channel 6 in glomerular podocytes

Objective To observe the changes of foot processes, expression and distribution of transient receptor potential cation channel 6 (TRPC6) in podocytes by puromycin aminonucleoside (PAN) and dexamethasone (DEX) intervention, then to investigate the function of TRPC6 in podocytes and its relation to proteinuria in kidney diseases. Methods Podocytes cultured in vitro were divided into three group: control group, PAN stimulation group and DEX intervention group. Mouse podocyte cell line (MPC5) were cultured in 0.02% dimethyl sulfoxide (DMSO) in control group, subjected to PAN (50 μg/ml) treatment alone or with DEX (1 μmol/L) in other two groups for 8 h, 24 h, 48 h. The podocyte morphology was observed and took pictures by phase - contrast microscope, then the differences of morphology and areas were analyzed. The distribution, mRNA expression and protein expression of TRPC6 were detected by indirect immunocyto-fluorescence, real-time quantitative PCR and Western blotting, respectively. Results The well - developed podocyte arborization and interconnection was formed in control group, but PAN led to significant shrinkage of podocytes (P＜0.05), together with podocyte foot process retraction, effacement and loss of cell contact. DEX significantly prevented the shrinkage and apoptosis of podocytes. The apoptosis rate was significantly increased after PAN stimulated 48 h (P＜0.05). Real-time quantitative PCR and Western blotting found TRPC6 mRNA and protein expression were prone to increase in PAN group compared with control group (P＜0.05). The distribution of TRPC6 becamed abnormal in PAN group. DEX decreased TRPC6 mRNA and protein expression at 48 h compared with PAN group (P＜0.05). The abnormal distribution of TRPC6 was also alleviated by the protection of DEX. Conclusion DEX exerts a direct action to podocyte which retains the integrity of slit diaphragm against podocyte injury, and alleviates proteinuria via stabilizing mRNA, protein expression and distribution of TRPC6.     

The role of reactive oxygen species and apoptosis in the pathogenesis of varicocele in a rat model and efficiency of vitamin E treatment

We investigated role of reactive oxygen species (ROS) and apoptosis in the pathogenesis of infertility in experimental model of varicocele. The protective effect of vitamin E was also examined. Three groups of rats were constructed as the first group had sham operation, experimental varicoceles were established by partial ligation of the left renal vein in later two groups. Third group had received vitamin E. Production of ROS was determined by chemiluminescence assay (CL). The in situ end labelling technique was utilized to investigate apoptosis. Tissue vitamin E levels were measured by high performance liquid chromatography. The differences between luminol enhanced CL levels of groups were not statistically significant. However, the difference between CL levels of lucigenin probe in left testicles of sham and varicocele groups were statistically significant ( p = 0.0007). Similarly, the results of the third group receiving vitamin E significantly differed from the varicocele group ( p = 0.0025). The difference of apoptotic index was also statistically significant between sham and varicocele groups ( p = 0.0038). Although the values of apoptotic index detected in the vitamin E group were lower compared with the varicocele group, the difference was not significant. This study proposes that ROS production and apoptosis in the testicles were induced with experimental varicocele. Vitamin E had a protective role. An increased rate of apoptosis with experimental varicocele suggests a molecular alteration, which may involve ROS overproduction as the triggering mechanism. Consequently, this study indicates an association between varicocele and infertility at molecular level through stimulation of ROS and apoptosis.