Panax quinquefolium saponins protect rat myocardium from ischemia/reperfusion injury through attenuating excessive endoplasmic reticulum stress

AIM: To investigate whether excessive endoplasmic reticulum stress (ERS) is involved in the protective mechanism of Panax quinquefolium saponins (PQS) against ischemia/reperfusion (I/R) injury in rat myocardium. METHODS: The model of myocardial I/R injury in vivo was made by ligating the left anterior descending artery for 45 min followed by 24 h of reperfusion in SD rats. The hemodynamics and serum content of cardiac troponin T (cTnT) were measured. The myocardial infarct size was measured by Evans blue and 2, 3, 5-triphenyltetrazolium chloride (TTC) staining. Cardiomyocyte apoptosis was detected using in situ TDT-mediated dUTP nick end labeling (TUNEL). The protein levels of glucose-regulated protein 78 (GRP78), calreticulin (CRT), C/EBP homologous protein (CHOP), caspase-12, apoptosis-associated proteins Bax and Bcl-2 were determined by Western blotting. RESULTS: Compared with I/R group, the mean arterial pressure in PQR+IR group was decreased by 32.0%, and left ventricular±dp/dtmax was increased by 64.0% and 35.0%, respectively.The serum content of cTnT was decreased by 53.3%, the percentage of area of necrosis (AN)/area at risk (AAR) was reduced by 65.5% and the apoptosis rate was decreased by 54.9%.The myocardial pathological changes were improved. Bcl-2 protein expression was increased by 110.0% and that of Bax was decreased by 47.8%. CRT protein expression was decreased by 43.4 %, CHOP protein expression and the protein level of cleaved caspase-12 were decreased by 38.6% and 23.7% in PQS+I/R group. CONCLUSION: PQS alleviates I/R injury in myocardium by inhibition of excessive ERS.     

Curcumin attenuates lung ischemia-reperfusion injury in mice through inhibiting JNK pathway and excessive endoplasmic reticulum stress

AIM: To investigate the role of curcumin (Cur) in attenuating lung ischemia-reperfusion (I/R) injury by inhibiting c-Jun N-terminal kinase(JNK) pathway and excessive endoplasmic reticulum stress (ERS) in mice. METHODS: Mouse model of lung I/R injury in situ was established in the left lung in vivo. Sixty mice were randomly divided into 6 groups (n=10 in each group), including sham group, I/R group, dimethyl sulfoxide solvent control group (I/R+DMSO group) and curcumin groups (I/R+ low, medium or high dose of Cur group). Left lung tissue was isolated after the experiment. The ratio of wet lung weight to dry lung weight (W/D), and total lung water content (TLW) were measured. The histological structure and ultrastructure of the left lung were observed under light and electron microscopes, and scored by alveolar damage index of quantitative assessment (IQA). The mRNA expression and protein levels of JNK and GRP78 were measured by RT-PCR and Western blotting. Apoptotic cells in the lung tissue were determined by TUNEL method. RESULTS: Compared with sham group, all indexes above in I/R group and DMSO group were significantly increased. No significant difference of all indexes between I/R group and DMSO group was observed. Compared with DMSO group, the indexes above in low, medium and high doses of Cur groups were decreased, especially in high dose of Cur group, but the expression level of GRP78 had no statistical difference. CONCLUSION: I/R induces excessive ERS in the lung tissue and results in lung injury. Cur has a protective effect on lung against I/R injury, which may be related to inhibition of apoptosis mediated by JNK pathway in ERS.     

PQS attenuates cardiomyocyte apoptosis induced by thapsigargin through inhibiting endoplasmic reticulum stress

AIM:To study the effect of Panax quinquefoliumsaponin (PQS) on cardiomyocyte apoptosis induced by thapsigargin (TG). METHODS:Primary cultured cardiomyocytes from neonatal SD rats were divided into control group, TG group, PQS (40 mg/L, 80 mg/L and 160 mg/L)+TG group, si-PERK+TG group, and mock+TG group. The cells were treated with 1 μmol/L TG for 24 h to induce apoptosis. The PERKgene in the cardiomyocytes was knocked down by RNAi. The cell viability was detected by CCK-8 assay. Apoptosis was analyzed by flow cytometry. Wes-tern blotting was used to determine the expression of ERS molecules GRP78, CRT, ATF4 and CHOP, anti-apoptosis protein Bcl-2 and pro-apoptosis protein Bax. RESULTS:Compared with control group, TG significantly and the apoptosis, reduced the cell viability (P<0.05), increased the phosphorylation of PERK and eIF2α, increased the expression of GRP78, CRT, ATF4, CHOP and pro-apoptosis protein Bax, and decreased the expression of anti-apoptosis protein Bcl-2 (P<0.05). Compared with TG group, PQS treatment (160 mg/L) significantly reduced the apoptosis and increased the cell viability (P<0.05). All the 3 different concentrations of PQS significantly increased the expression of anti-apoptosis protein Bcl-2 and reduced the expression of pro-apoptosis protein Bax (P<0.05) in a dose-dependent manner. PQS pretreatment and knockdown of PERK both reduced the protein levels of GRP78, CRT, PERK, p-PERK, eIF2α, p-eIF2α, ATF4, CHOP and pro-apoptosis protein Bax, and increased the expression of anti-apoptosis protein Bcl-2 (P<0.05). CONCLUSION: PQS at concentration of 160 mg/L attenuated cardiomyocyte apoptosis induced by TG. PQS had the similar effect as PERKknockdown on cardiomyocyte apoptosis. The mechanism may be associated with inhibiting PERK-eIF2α-ATF4-CHOP pathway of ERS-related apoptosis.     

Fuzi polysaccharide protects neonatal rat cardiomyocytes with hypoxia-reoxygenation by inhibiting endoplasmic reticulum stress

AIM: To investigate whether the protection mechanism of Fuzi polysaccharide (FPS) is related to inhibition of endoplasmic reticulum stress in cultured neonatal rat cardiomyocytes with hypoxia/reoxygenation (H/R). METHODS: Cultured rat myocardial cells were divided into control group, H/R group (hypoxia for 3 h and reoxygenation for 6 h) and different concentrations of FPS (0.1 g/L, 1 g/L, 10 g/L or 20 g/L) +H/R groups. The cell survival was detected by MTT assay and cell apoptosis of cardiomyocytes was measured by flow cytometry using Annexin V-FITC staining. The expression of glucose-regulated protein 78 (GRP78), CCAAT/enhancer-binding protein homologous protein (CHOP) and caspase-12 were determined by Western blotting. The mRNA expression of CHOP and caspase-12 was detected by quantitative PCR. RESULTS: After reoxygenation, the expression of GRP78, CHOP and caspase-12 in cardiomyocytes was increased. Compared with H/R group, the expression of GRP78, CHOP and caspase-12 in FPS+H/R groups was significantly inhibited, the survival rate of cardiomyocytes was increased and the apoptosis of cardiomyocytes was inhibited. This protective effect of FPS was in a dose-dependent manner and reached its peak at 10 g/L. CONCLUSION: Fuzi polysaccharide protects cardiomyocytes from H/R injury. The mechanism is related to inhibiting endoplasmic reticulum stress.     

欢迎订阅《园艺学报》

《园艺学报》是中国园艺学会和中国农业科学院蔬菜花卉研究所主办的学术期刊,创刊于1962年,刊载有关果树、蔬菜、观赏植物、茶及药用植物等方面的学术论文、研究报告、专题文献综述、问题与讨论、新技术新品种以及园艺研究动态与信息等,适合园艺科研人员、大专院校师生及农业技术推广部门专业技术人员阅读参考。《园艺学报》是中文核心期刊,被英国《CAB文摘数据库》、美国CA化学文摘、日本CBST科学技术文献速     

Effects of naringenin on PI3K/AKT signaling pathway and endoplasmic reticulum stress and its related apoptotic pathways in rats with myocardial ischemia/reperfusion injury

AIM To observe the effect of naringenin on cardiac injury in ischemia/reperfusion （I/R） rats, and to explore whether the role of naringenin is involved in PI3K/AKT signaling pathway and endoplasmic reticulum stress and its related apoptotic pathways. METHODS SD rats （n=48） were randomly divided into sham operation （sham） group, model （I/R） group, naringenin treatment （NAR） group and naringenin+LY294002 （NL） group. Myocardial I/R injury model was prepared by ligation of left anterior descending coronary artery of rats for 30 min followed by reperfusion for 120 min. After reperfusion, the serum levels of cardiac troponin I （cTnI） was measured by ELISA. HE staining, TTC staining and TUNEL staining were used to detect the myocardial histopathological changes, myocardial infarction area and myocardial cell apoptotic rate. The mRNA levels of endoplasmic reticulum stress-related indicators glucose-regulated protein 78 （GRP78）, C/EBP homologous protein （CHOP） and caspase-12 were detected by RT-qPCR. The protein levels of cleaved caspase-3, GRP78, CHOP, caspase-12, p-PI3K and p-AKT were determined by Western blot. RESULTS Compared with I/R group, the serum content of cTnI, myocardial pathological damage, myocardial infarction area and myocardial cell apoptotic rate were significantly reduced （P<0.05）, the protein levels of cleaved caspase-3, GRP78, CHOP and caspase-12 were decreased （P<0.05）, and the protein levels of p-PI3K and p-AKT were increased in NAR group （P<0.05）. LY294002 attenuated the protective effect of naringenin to some extent. CONCLUSION Naringenin reduces myocardial I/R injury in rats possibly by activating PI3K/AKT signaling pathway and subsequently regulating endoplasmic reticulum stress and its related apoptotic pathways.     

Relationship between histone H3K36 trimethylation and acute renal injury induced by ischemia/reperfusion

AIM: To observe the expression change of H3K36 trimethylation (H3K36me3) in acute kidney injury (AKI) induced by ischemia/reperfusion (IR) and analyze its correlation with SMYD2 and renal injury, and to provide a new target for clinical treatment of IR-AKI. METHODS: The ICR mice (n=30) were randomly divided into IR group (n=15) and sham operation group (sham group, n=15). The AKI model was established by clamping bilateral renal pedicles for 45 min. The serum and renal tissues of the mice were collected after the model was established for 24 h. The levels of blood urea nitrogen (BUN) and serum creatinine (SCr) were detected by biochemical method. The pathological changes of the kidney were observed by HE staining. The changes of NGAL and cleaved caspase-3 were observed by immunohistochemical (IHC) staining. The protein levels of NGAL, SMYD2, H3K36me3, p-P53, P53, cleaved caspase-3, Bax, Bcl-2, STAT3, p-STAT3, JNK and p-JNK1/2/3 in the renal tissues were determined by Western blot. The relationship between H3K36me3 and SMYD2/NGAL was analyzed by Pearson correlation method. RESULTS: Compared with sham group, BUN and SCr levels of the mice in IR group were significantly increased (P<0.05). HE staining showed significant edema, abscission and necrosis in renal tubular epithelial cells of the micc in IR group, and abscission of brush border and large amount of cell debris in the lumen were also observed. The IHC staining results showed that the protein levels of NGAL and cleaved caspase-3 in IR group were significantly increased. The results of Western blot showed that the protein levels of NGAL, SMYD2, H3K36me3, p-P53, cleaved caspase-3, Bax, STAT3, p-STAT3, JNK and p-JNK1/2/3 in IR group were significantly up-regulated (P<0.05), while the Bcl-2 levels were significantly down-regulated (P<0.05). The correlation analysis showed that H3K36me3 was positively correlated with the levels of SMYD2 and NGAL. CONCLUSION: H3K36me3 is closely related to SMYD2 and renal injury in IR-AKI mice, and the up-regulated expression of H3K36me3 may be involved in the regulation of IR-AKI occurrence and development together with the activation of STAT3 and JNK signaling pathways.     

苹果miR396家族鉴定及在不定根发育过程中的表达分析

分析了苹果miR396家族进化特性及其在苹果不定根发育过程中的表达模式。结果表明:苹果miR396家族有4条成熟体和7条前体序列(pre-miRNA)。Mfold预测显示Pre-miR396家族7个成员序列均可形成典型稳定的茎环二级结构,最小折叠自由能介于–62.9 kal·mol^-1(pre-miR396b)～–51.9kal·mol^-1(pre-miR396g)之间。系统发育进化树分析显示,pre-miR396家族亲缘关系可分为3个亚组(G1、G2、G3),每个亚组内基因数量不同,分别含有11、9、19个。靶基因预测显示,苹果miR396靶基因包括MdGRF1、MdGRF2和MdGRF5等,降解组测序进一步验证了mi R396对其候选靶基因MdGRF1、MdGRF2和MdGRF5的剪切关系。苹果miR396家族成员在侧根和果实中的表达量显著高于其他组织,其候选靶基因表达量则在花芽和腋芽中显著高于其他组织;不定根发育过程中,miR396家族不同成员表达模式存在显著差异,整体上呈上调表达趋势,其候选靶基因呈下调表达趋势;外源IBA处理显著诱导...     

Quercetin reduces microvascular permeability induced by ischemia/reperfusion injury through SIRT1 signaling

AIM To investigate whether quercetin (Que) attenuates microvascular injury after myocardial ischemia/reperfusion (I/R), and whether its mechanism is related to the up-regulation of silent information regulator 1 (SIRT1). METHODS In vivo, SD rats (220~250 g) were randomly divided into sham group (only threading without ligation), I/R group (ischemia 30 min/reperfusion 60 min), I/R+Que group (10 mg/kg Que injected intravenously 15 min before reperfusion) and I/R+Que+EX527 group (1 mg/kg EX527 injected intravenously 15 min before Que). The protein expression of SIRT1 in each group was determined by Western blot. The effect of Que on the morphological changes of myocardial microvascular was estimated by HE staining. The contents of endothelial damage markers and inflammatory factors in peripheral blood serum of the rats in each group were measured by ELISA. In vitro, Transwell chamber was used to culture H5V cells and then the influence of Que on the permeability of endothelial cells was evaluated. The expression of myosin light chain phosphatase(MLCP), zonula occludens-1 (ZO-1) and cytoskeleton was determined by Western blot and immunofluorescence method. RESULTS The results of Western blot showed that SIRT1 was significantly reduced by I/R in the myocardial tissue. Que increased the expression of SIRT1 after I/R, whereas EX527 significantly inhibited this effect (P<0.05). Que reduced the incidence of I/R arrhythmia, alleviated microvascular damage and inhibited the infiltrating of inflammatory cells,as well as decreased levels of the endothelial injury markers (E-selectin and VCAM-1) and proinflammatory factors (PAF, IL-1α and IL-6). While EX527 significantly reduced these effects of Que by inhibiting SIRT1. Cultured H5V cells showed that hypoxia/reoxygenation resulted in increased permeability of endothelial cells and decreased expression of ZO-1 and MLCP. However, Que, which up-regulated expression of SIRT1, significantly reduced the permeability of endothelial cells significantly and increased the expression of ZO-1 and MLCP. Meanwhile, the cytoskeleton remodeling basically disappeared. EX527, which down-regulated expression of SIRT1, significantly inhibited the above effects of Que. CONCLUSION Que attenuates myocardial I/R induced microvascular injury. The up-regulation of SIRT1 is involved in this mechanism.     

Role of endoplasmic reticulum stress in Bim-mediated cardiomyocyte apoptosis induced by hypoxia

AIM:To investigate the role of endoplasmic reticulum stress (ERS) in the process of Bim-mediated cardiomyocyte apoptosis induced by hypoxia. METHODS:Cardiomyocytes were isolated from neonatal Sprague-Dawley rats aged 1~3 days, and primarily cultured in vitro. The antibody targeting α-striated muscle actin was used to identify the cardiomyocytes. The siRNAs targeting bim were transfected into cardiomyocytes with liposome, followed by detecting the expression of Bim by Western blotting. Cardiomyocytes were divided into five groups: blank control group, hypoxia group, hypoxia+liposome group, hypoxia+negative control siRNA group and hypoxia+Bim-siRNA group. The cell viability was determined by MTT assay, and the cell apoptotic rate and the intracellular calcium concentration were measured by flow cytometry. The protein expression of caspase-12 and inositol 1,4,5-triphosphate (IP3) was detected by Western blotting. RESULTS:Immunohistochemical identification confirmed that rat cardiomyocytes were successfully cultured. Green fluorescence was observed in the cells transfected with negative control siRNA under fluorescence microscope. The expression of Bim was obviously inhibited after transfected with Bim-siRNAs and the silencing efficiency of Bim-siRNA-2 was the highest (86.73%). Compared with blank control group, the viability of cardiomyocytes in hypoxia group was significantly reduced (P<005). Compared with hypoxia+negative control siRNA group, the viability of cardiomyocytes in hypoxia+Bim-siRNA group was significantly increased (P<005). The apoptotic rate and the intracellular calcium concentration of cardiomyocytes were obviously increased in hypoxia group (P<0.01), and were both decreased after bim silencing (P<005 or P<0.01). The expression of caspase-12 and IP3 was up-regulated in hypoxia group (P<005), and was down-regulated after bim silencing (P<005 or P<0.01). CONCLUSION: Cardiomyocyte apoptosis induced by hypoxia can be inhibited by silencing the expression of bim gene. Caspase-12 and IP3, as markers of ERS, may participate in the process of Bim-mediated cardiomyocyte apoptosis induced by hypoxia.     

Effect of SET7/9-mediated endoplasmic reticulum stress on arsenic-induced hepatocyte apoptosis

AIM:To investigate the effect of SET7/9 (SET domain containing 7/9)-mediated endoplasmic reticulum stress (ERS) on protein kinase R-like endoplasmic reticulum kinase (PERK) signaling pathway, and to explore the mechanisms of arsenic-induced hepatocyte apoptosis. METHODS:Human liver LO2 cells were divided into control group, arsenic poisoning model group, negative transfection group and SET7/9 siRNA transfection group. The apoptosis of the LO2 cells in each group was analyzed by flow cytometry. The protein levels of SET7/9, glucose-regulated protein 78 (GRP78), PERK and p-PERK in the LO2 cells of each group were observed by Western blot. RESULTS:Inhibition of SET7/9 expression reduced the apoptotic rate of arsenic-induced LO2 cells. Arsenic exposure increased the expression of SET7/9 in the LO2 cells. Arsenic exposure increased the protein levels of GRP78 and p-PERK in the LO2 cells, but decreased the protein levels of GRP78 and p-PERK after transfection with SET7/9 siRNA (P<0.05). CONCLUSION:Arsenic exposure induces hepatocyte apoptosis by increasing SET7/9 to activate ERS by PERK signaling pathway.     

Effects of calpain-2 and autophagy-related protein 5 on hepatocyte apoptosis induced by endoplasmic reticulum stress

AIMTo investigate the effects of calpain-2 and autophagy-related protein 5 (Atg5) on apoptosis of BRL-3A rat normal liver cells during endoplasmic reticulum stress (ERS) induced by dithiothreitol (DTT). METH?ODS: BRL-3A cells were treated with DTT at 2.0 mmol/L for 0, 6, 12 and 24 h to induce ERS. Real-time cell analysis (RTCA) was used to measure the effect of DTT on BRL-3A cell proliferation. Apoptosis and cell cycle distribution were analyzed by flow cytometry. The mRNA expression of calpain-2 and Atg5 was detected by real-time PCR. The protein levels of calpain-2, Atg5, Atg7, Atg12 and microtubule-associated protein 1 light chain 3 (LC3) were determined by Western blot. The interaction between calpain-2 and Atg5 was investigated by co-immunoprecipitation (Co-IP). RESULTSThe proliferation of BRL-3A cells treated with DTT was significantly inhibited. The apoptosis of BRL-3A cells was significantly increased after DTT treatment for 6, 12 and 24 h as compared with 0 h group (P<0.05). The cell cycle was arrested in G₁ phase after DTT treatment (P<0.05). After DTT treatment for 6, 12 and 24 h, the mRNA expression of calpain-2 and Atg5 in the BRL-3A cells was significantly increased as compared with 0 h group (P<0.05). The protein levels of calpain-2, Atg12 and Atg7 in the cells treated with DTT for 6, 12 and 24 h were significantly higher than those in 0 h group, and the ratio of LC3-II/LC3-I was also significantly higher than that in 0 h group, while Atg5 expression was significantly lower than that in 0 h group (P<0.05). The results of Co-IP found that the anti-calpain-2 antibody precipitated Atg5 protein from the cell lysates, and the anti-Atg5 antibody also precipitated calpain-2 from the cell lysates, which confirmed the interaction between calpain-2 and Atg5. CONCLUSION Calpain-2 may participate in ERS-induced hepatocyte apoptosis by interacting with Atg5.     

Curcumin attenuates rat lung ischemia/reperfusion injury by interfering with autophagy

AIM To investigate the role of curcumin （CUR） in lung ischemia/reperfusion （I/R） injury （LIRI） and its relationship with autophagy. METHODS 40 SD rats were randomly divided into sham operation （sham） group, I/R group, solvent （DMSO） group, CUR group and CUR+rapamycin （CUR-Rap） group. The rats were intraperitoneally injected with normal saline, DMSO, CUR or CUR+Rap before operation. After the rat LIRI model was established, the lung tissues were taken to measure W/D, TLW, IAR, and the contents of SOD and MDA were also measured to indicate the oxidative stress level. Light and electron microscopes were used to observed the morphology and ultrastrucure of lung tissues. The expression levels of autophagy-related proteins were determined by Western blot to evaluate autophagy levels. RESULTS Compared with sham group, wet weight/dry weight （W/D）, total lung water （TLW）, injured alveoli rate（IAR） and malondialdehyde （MDA） content in all other groups were increased, superoxide dismutase （SOD） activity was decreased, the levels of autophagy were increased （P<0.05）, and lung tissue injury and cell ultrastructural damage were aggravated in CUR group. Compared with DMSO group, W/D, TLW and IAR and MDA content were decreased, SOD activity was decreased, autophagy levels were also decreased （P<0.05）, and lung tissue and cell ultrastructural damage were attenuated. Compared with CUR group, W/D, TLW, IAR and MDA content were increased, SOD activity declined, the autophagy levels were increased （P<0.05）, and damage of lung tissues and cells were more serious in CUR-Rap group. CONCLUSION Curcumin attenuates the lung I/R injury in rats, and its mechanism may be related to the reduction of oxidative stress and the inhibition of autophagy.     

Effect of endoplasmic reticulum stress on brain injury following chronic intermittent hypoxia in growing rats

AIM: To explore the role of endoplasmic reticulum stress (ERS) in brain injury following chronic intermittent hypoxia in growing rats and the protective effect of treatment with salubrinal. METHODS: Healthy male SD rats (3~4-week-old, 100~120 g, n=64) were randomly assigned to 8 groups (8 rats in each group):the groups of intermittent hypoxia for 2 and 4 weeks (2IH and 4IH), the groups of control (C) for 2 and 4 weeks (2C and 4C), the groups of dimethylsulfoxide (DMSO) for 2 and 4 weeks (2DMSO and 4DMSO) and the groups of salubrinal for 2 and 4 weeks (2SAL and 4SAL). The 8-arm radial maze was used to assess the working memory error (WME), reference memory error (RME) and total error (TE) of the rats. The changes of neuronal apoptosis in the hippocampus were observed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. The activity of superoxide dismutase (SOD), and the protein levels of endoplasmic reticulum stress marker compounds, C/EBP homologous protein (CHOP), phosphorylated eukaryotic translation initiation factor 2 alpha (p-eIF2α) and phosphorylated protein kinase R-like endoplasmic reticulum kinase (p-PERK), were analyzed. RESULTS: Chronic intermittent hypoxia (CIH) significantly increased RME, WME, TE and neuronal apoptotic index (AI) (P<0.01), and decreased the activity of SOD in the hippocampus and serum (P<0.01). The protein levels of p-PERK and CHOP progressively increased in hippocampus in IH groups (P<0.01), and p-eIF2α was downregulated (P<0.05). Treatment with salubrinal significantly decreased RME (P<0.05), WME (P<0.05), TE (P<0.01) and AI (P<0.01), and increased the activity of SOD (P<0.01). Salubrinal induced the phosphorylation of eIF2α significantly after CIH in hippocampus and downregulated the level of CHOP (P<0.01). CONCLUSION: Chronic intermittent hypoxia upregulates the protein levels of p-PERK and CHOP in the hippocampus, and decreases p-eIF2α protein and the activity of SOD. Salubrinal, a selective inhibitor of eIF-2α dephosphorylation, increases the activity of SOD and prevents CHOP protein activation throughout CIH exposure. Our findings suggest ERS-mediated cell apoptosis is one of the underlying mechanisms of cognitive dysfunction in OSAHS children. Further, a specific ERS inhibitor salubrinal should be tested for neuroprotection against CIH-induced brain injury.     

Excessive endoplasmic reticulum stress induces apoptotic cell death in chronic cyclosporine A nephrotoxicity

AIM：To investigate the impact of excessive endoplasmic reticulum stress on apoptotic cell death in a rat model of chronic cyclosporine A (CsA) nephrotoxicity. METHODS：Male Sprague-Dawley rats on a low-salt diet were subcutaneously injected with vehicle (olive oil, 1 mL·kg-1·d-1) or CsA (15 mg/kg) daily for 1 or 4 weeks. Tubulointerstitial fibrosis and apoptotic cell death were estimated by trichrome staining and TUNEL staining. In addition, immunohistochemistry and immunoblotting were used to evaluate the expression of immunoglobulin-binding protein (BiP), eukaryotic initiation factor 2α (eIF2α), growth arrest and DNA damage-inducible protein 153 (GADD153), caspase-12 and caspase-3. RESULTS：The rats treated with CsA for 1 week did not develop tubulointerstitial fibrosis and TUNEL-positive cells, whereas 4-week treatment with CsA induced typical tubulointerstitial fibrosis and increased TUNEL-positive cells. CsA induced a significant increase in BiP and caspase-12 expression peaked at 1 week, and then returned to normal levels at 4 weeks. In contrast, the expression of eIF2α, GADD153 and caspase-3 in CsA-treated rat kidneys were significantly increased in a time-dependent manner. CONCLUSION：Excessive endoplasmic reticulum stress causes apoptotic cell death by depleting molecular chaperones and stimulating the proapoptotic pathway in chronic CsA nephrotoxicity.     

Prostaglandin E1 protects heart after myocardial infarction by inhibiting endoplasmic reticulum stress in rats

AIM To investigate the effect of prostaglandin E1 (PGE1) on heart after myocardial infarction (MI) in rats and its related molecular mechanism. METHODS Fifty male SD rats were divided into sham group, model group and model+PGE1 group. The MI rat model was established by ligation of left anterior descending coronary artery. Cardiac function in the rats was detected by echocardiogaphy. The myocardial histomorphologic changes were evaluated by HE and Masson staining. The MI area was measured by TTC staining. The cardiomyocyte death was detected by TUNEL staining. The protein levels of endoplasmic reticulum stress (ERS)-related factors glucose-regulated protein 78 (GRP78), C/EBP homologous protein (CHOP) and caspase-12, and apoptosis-related factors Bcl-2, Bax and cleaved caspase-3 were determined by immunofluorescence staining and Western blot. RESULTS Compared with sham group, the cardiac function in model group was decreased, with significant myocardial pathological changes. The MI area was enlarged, and the death of cardiomyocytes was promoted. The protein levels of GRP78, CHOP, caspase-12, Bax and cleaved caspase-3 in the myocardial tissues were significantly increased, while Bcl-2 was decreased (P<0.01). Compared with model group, the cardiac function in model+PGE1 group was significantly improved, and the myocardial pathological damage was significantlty attenuated. The MI area and myocardial cell death were significantly reduced. The protein levels of GRP78, CHOP, caspase-12, Bax and cleaved caspase-3 in the myocardial tissues were significantly decreased, while Bcl-2 was increased (P<0.01). CONCLUSION PGE1 reduces collagen deposition and inflammation, and improves cardiac function by reducing ERS level, thus protecting cardiomyocytes from MI damage.     

Effect of acteoside on behavioral changes and endoplasmic reticulum stress in prefrontal cortex of depressive rats

AIM: To explore the effect of acteoside on behavioral changes and endoplasmic reticulum stress (ERS) in prefrontal cortex of depressive rats. METHODS: Sprague-Dawley (SD) rats (n=108) were randomly divided into 6 groups:control group, model group, fluoxetine (20 mg/kg) group, low-dose (30 mg/kg) acteoside group, medium-dose (60 mg/kg) acteoside group and high-dose (120 mg/kg) acteoside group, with 18 rats in each group. The depressive-like rat model was established by chronic unpredictable mild stress (CUMS) combined with solitary way for 28 d. The rats in fluoxetine group and acteoside groups were treated with fluoxetine (20 mg/kg) or acteoside (30 mg/kg, 60 mg/kg and 120 mg/kg) once daily by intragastric administration for 3 weeks. The rats in control group and model group were both given equal volume of saline by intragastric administration for 3 weeks. The behavioral changes were detected by the open-field test and sugar preference experiment. The protein expression of glucose-regulated protein 78 (GRP78) and C/EBP homologous protein (CHOP) was assessed by immunofluorescence and Western blot. The caspase-3 activity was measured by spectrophotometer. RESULTS: Compared with control group, the total distance, time spent in the center and sugar intake were all decreased, the expression of GRP78 and CHOP was increased, and the activity of caspase-3 was increased in model group, fluoxetine group and acteoside groups (P<0.05). Compared with model group, the total distance, time spent in the center and sugar intake were increased, the expression of GRP78 and CHOP was reduced, and the activity of caspase-3 was decreased (P<0.05) in fluoxetine group and acteoside groups. CONCLUSION: Acteoside improves depressive-like behaviors in depressive rats, which may be related to the inhibition of ERS and neuronal apoptosis in prefrontal cortex.