Baicalin protects against renal interstitial fibrosis in mice by inhibiting the TGF-β/Smad signalling pathway

ContextBaicalin, a flavonoid extracted from radix scutellariae, possesses various pharmacological effects, including protective effects on renal interstitial fibrosis (RIF), but its possible role and mechanisms have not been fully elucidated.ObjectiveThis study explores the protective effects and mechanisms of baicalin on RIF.Materials and methodsC57BL/6 male mice were divided into six groups: sham, model, low baicalin, middle baicalin, high baicalin and positive drug groups. The unilateral ureteral obstruction (UUO) model of RIF was constructed and treated with baicalin doses (10, 20 and 40 mg/kg) and a positive control drug (valsartan, 8 mg/kg). H&E staining was used to observe the pathological changes in renal tissues, Masson staining was performed to evaluate collagen deposition in renal tissues, and immunohistochemical examination was adopted to determine α-SMA and extracellular matrix (ECM) expression. Primary mouse fibroblasts were isolated, extracted and treated with baicalin and/or TGF-β. qRT-PCR and enzyme-linked immunosorbent assay (ELISA) were applied to detect the inflammatory responses. Moreover, ECM and TGF-β/Smad expression levels were evaluated by western blot assay.ResultsBaicalin ameliorated RIF in UUO mice by inhibiting fibrosis and inflammatory responses. The TGF-β/Smad pathway was significantly suppressed in the UUO mouse model. Additionally, baicalin significantly inhibited ECM expression and inflammatory factors in fibroblasts treated with TGF-β. TGF-β/Smad pathway activation was significantly decreased in fibroblasts.Discussion and conclusionsThese findings support the use of baicalin as a potential therapeutic option for the treatment of RIF by possibly inhibiting the TGF-β/Smad signalling pathway.     

吡非尼酮通过miRNA-425-5p调控TGF-β/Smad通路对大鼠心肌纤维化的影响

目的 探讨吡非尼酮通过调控miRNA-425-5p及转化生长因子（TGF）-β/Smad通路改善心肌梗死大鼠心肌纤维化程度的作用。方法 将60只雄性SD大鼠分为3组：假手术组（不结扎冠状动脉）、模型组、吡非尼酮组（吡非尼酮0.3 g/kg灌胃）。造模4周后采用心脏多普勒超声评价各组大鼠心脏功能; 酶联免疫吸附试验检测血浆中白细胞介素6（IL-6）、Ⅰ型胶原蛋白α2（COL1α2）、Ⅲ型胶原蛋白α1（COL3α1）的水平;采用Masson染色法评价大鼠心肌纤维化程度,使用Image-Pro Plus 6.0分析各组心肌胶原容积分数;Western blot检测心肌组织中TGF-β1、Smad2、Smad3蛋白表达水平;实时荧光定量PCR（qPCR）检测心肌组织中TGF-β1和miRNA-425-5p表达水平。同时在体外分离、培养乳鼠心肌成纤维细胞,分为对照组（不加任何物质）、miRNA-425-5p mimic组（加入转染miRNA-425-5p mimic）、吡非尼酮组（加入1.5 g/L的吡非尼酮）。采用qPCR检测各组miRNA-425-5p和TGF-β1 mRNA表达水平。结果 模型组大鼠与假手术组相比心脏左心室舒张末期内径（LVEDd）、左心室收缩末期内径（LVESd）增大,左心室射血分数（LVEF）、左心室短轴缩短率（FS）降低（P<0.05）;Masson染色及定量分析结果显示心肌纤维化加重;炎性因子IL-6、COL3α1、COL1α2水平明显升高（P<0.05）;心肌组织TGF-β1、Smad2、Smad3蛋白表达升高,miRNA-425-5p表达水平降低（均P<0.05）。吡非尼酮组与模型组相比,LVEDd、LVESd缩小,LVEF、FS升高（P<0.05）,Masson染色及定量分析结果示心肌纤维化程度减轻,血浆炎性因子IL-6、COL3α1、COL1α2水平明显降低（P<0.05）;心肌组织TGF-β1、Smad2、Smad3蛋白表达水平降低,miRNA-425-5p表达水平升高（均P<0.05）。体外细胞实验结果表明,miRNA-425-5p mimic组与对照组相比,miRNA-425-5p表达水平升高,TGF-β1 mRNA表达水平降低（P<0.05）。吡非尼酮组与对照组相比,miRNA-425-5p表达水平升高,TGF-β1 mRNA表达水平降低（P<0.05）。结论 吡非尼酮可通过调节miRNA-425-5p表达水平调控TGF-β/Smad信号通路,减轻心肌纤维化,改善心肌梗死后心力衰竭大鼠心脏功能。     

Patchouli alcohol protects against myocardial ischaemia–reperfusion injury by regulating the Notch1/Hes1 pathway

ContextPatchouli alcohol (PA) has protective effects on cerebral ischaemia/reperfusion (I/R) injury, but its efficacy on myocardial ischaemia-reperfusion (MI/R) has yet to be addressed.ObjectiveTo examine the therapeutic effect of PA on myocardial ischaemia-reperfusion (I/R) injury.Materials and methodsC57BL/6 male mice were randomly divided into sham, MI/R, MI/R + PA-10, MI/R + PA-20 and MI/R + PA-40 groups. In vivo MI/R model was established by ligating the anterior descending coronary artery of the heart. In vitro stimulated IR cell model was constructed by using the rat cardiomyocyte H9C2 cell line. Mice in the treatment groups were intraperitoneally injected with PA (10, 20, 40 mg/kg) for 30 days then subjected to surgery, and cells in the experimental group were pre-treated with PA (1, 10 or 100 μmol/L). After treatment, mouse heart function, myocardial injury markers, myocardial infarction and Notch1/Hes1 expression, endoplasmic reticulum stress markers, and apoptosis-related proteins were determined.ResultsIn vivo, PA treatment improved hemodynamic parameter changes and myocardial enzymes, increased the left ventricular ejection fraction and left ventricular fractional shortening, reduced the left ventricular end-systolic diameter and inhibited CK-MB, cTnI and cTnT levels. In addition, PA attenuated myocardial tissue damage and apoptosis. PA treatment elevated Notch1, NICD and Hes1 levels and suppressed the levels of ATF4, p-PERK/PERK, and cleaved caspase-3/caspase-3 in vitro and in vivo.Discussion and conclusionPA protects against MI/R, possibly by modulating ER stress, apoptosis and the Notch1/Hes1 signalling pathways. These findings indicate that PA may be a promising candidate for treating ischaemic heart diseases.     

Mangiferin ameliorates cardiac fibrosis in D-galactose-induced aging rats by inhibiting TGF-β/p38/MK2 signaling pathway

Aging is the process spontaneously occurred in living organisms. Cardiac fibrosis is a pathophysiological process of cardiac aging. Mangiferin is a well-known C-glucoside xanthone in mango leaves with lots of beneficial properties. In this study, rat model of cardiac fibrosis was induced by injected with 150 mg/kg/d D-galactose for 8 weeks. The age-related cardiac decline was estimated by detecting the relative weight of heart, the serum levels of cardiac injury indicators and the expression of hypertrophic biomakers. Cardiac oxidative stress and local inflammation were measured by detecting the levels of malondialdehyde, enzymatic antioxidant status and proinflammatory cytokines. Cardiac fibrosis was evaluated by observing collagen deposition via masson and sirius red staining, as well as by examining the expression of extracellular matrix proteins via Western blot analysis. The cardiac activity of profibrotic TGF-β1/p38/MK2 signaling pathway was assessed by measuring the expression of TGF-β1 and the phosphorylation levels of p38 and MK2. It was observed that mangiferin ameliorated D-galactose-induced cardiac aging, attenuated cardiac oxidative stress, inflammation and fibrosis, as well as inhibited the activation of TGF-β1/p38/MK2 signaling pathway. These results showed that mangiferin could ameliorate cardiac fibrosis in D-galactose-induced aging rats possibly via inhibiting TGF-β/p38/MK2 signaling pathway.     

Salidroside orchestrates metabolic reprogramming by regulating the Hif-1α signalling pathway in acute mountain sickness

ContextRhodiola crenulata (Hook. f. et Thoms.) H. Ohba (Crassulaceae) is used to prevent and treat acute mountain sickness. However, the mechanisms underlying its effects on the central nervous system remain unclear.ObjectiveTo investigate the effect of Rhodiola crenulata on cellular metabolism in the central nervous system.Materials and methodsThe viability and Hif-1α levels of microglia and neurons at 5% O₂ for 1, 3, 5 and 24 h were examined. We performed the binding of salidroside (Sal), rhodiosin, tyrosol and p-hydroxybenzyl alcohol to Hif-1α, Hif-1α, lactate, oxidative phosphorylation and glycolysis assays. Forty male C57BL/6J mice were divided into control and Sal (25, 50 and 100 mg/kg) groups to measure the levels of Hif-1α and lactate.ResultsMicroglia sensed low oxygen levels earlier than neurons, accompanied by elevated expression of Hif-1α protein. Salidroside, rhodiosin, tyrosol, and p-hydroxybenzyl alcohol decreased BV-2 (IC₅₀=1.93 ± 0.34 mM, 959.74 ± 10.24 μM, 7.47 ± 1.03 and 8.42 ± 1.63 mM) and PC-12 (IC₅₀=6.89 ± 0.57 mM, 159.28 ± 8.89 μM, 8.65 ± 1.20 and 8.64 ± 1.42 mM) viability. They (10 μM) reduced Hif-1α degradation in BV-2 (3.7-, 2.5-, 2.9- and 2.5-fold) and PC-12 cells (2.8-, 2.8-, 2.3- and 2.0-fold) under normoxia. Salidroside increased glycolytic capacity but attenuated oxidative phosphorylation. Salidroside (50 and 100 mg/kg) treatment increased the protein expression of Hif-1α and the release of lactate in the brain tissue of mice.ConclusionsThese results suggest that Sal induces metabolic reprogramming by regulating the Hif-1α signalling pathway to activate compensatory responses, which may be the core mechanism underlying the effect of Rhodiola crenulata on the central nervous system.     

Peiminine inhibits myocardial injury and fibrosis after myocardial infarction in rats by regulating mitogen-activated protein kinase pathway

Myocardial infarction promotes cardiac remodeling and myocardial fibrosis, thus leading to cardiac dysfunction or heart failure. Peiminine has been regarded as a traditional anti-fibrotic Chinese medicine in pulmonary fibrosis. However, the role of peiminine in myocardial infarction-induced myocardial injury and fibrosis remained elusive. Firstly, rat model of myocardial infarction was established using ligation of the left coronary artery, which were then intraperitoneally injected with 2 or 5 mg/kg peiminine once a day for 4 weeks. Echocardiography and haemodynamic evaluation results showed that peiminine treatment reduced left ventricular end-diastolic pressure, and enhanced maximum rate of increase/decrease of left ventricle pressure (± dP/dt max) and left ventricular systolic pressure, which ameliorate the cardiac function. Secondly, myocardial infarction-induced myocardial injury and infarct size were also attenuated by peiminine. Moreover, peiminine inhibited myocardial infarction-induced increase of interleukin (IL)-1β, IL-6 and tumor necrosis factor-α production, as well as the myocardial cell apoptosis, in the rats. Thirdly, peiminine also decreased the myocardial fibrosis related protein expression including collagen I and collagen III. Lastly, peiminine reduced the expression of p38 and phosphorylation of extracellular signal-regulated kinase 1/2 in rat model of myocardial infarction. In conclusion, peiminine has a cardioprotective effect against myocardial infarction-induced myocardial injury and fibrosis, which can be attributed to the inactivation of mitogen-activated protein kinase pathway.     

Britanin relieves ferroptosis-mediated myocardial ischaemia/reperfusion damage by upregulating GPX4 through activation of AMPK/GSK3β/Nrf2 signalling

ContextFerroptosis was described as an important contributor to the myocardial ischaemia/reperfusion (MIR) injury, and britanin (Bri) was reported to exert antitumor and anti-inflammatory activities.ObjectiveOur study explores the effect and mechanism of Bri on MIR damage.Materials and methodsThe rat model of MIR was established by ligation of the left anterior descending coronary artery. Male Sprague–Dawley (SD) rats were divided into three groups: sham group (n = 6), MIR group (n = 6) and MIR + Bri group (n = 6; 50 mg/kg). Rats were intragastrically pre-treated with Bri or normal saline once daily for 3 days. To further verify the role and mechanism of Bri, H9C2 cells were subjected to hypoxia plus reoxygenation (H/R) to induce the in vitro model of MIR.ResultsCompared with MIR rats, Bri significantly decreased infarct area (22.50% vs. 38.67%), myocardial apoptosis (23.00% vs. 41.5%), creatine phosphokinase (0.57 U/mL vs. 0.76 U/mL), and lactate dehydrogenase levels (3.18 U/mL vs. 5.17 U/mL), concomitant with alleviation of ferroptosis. Mechanistically, Bri treatment induced the activation of the adenosine monophosphate activated protein kinase (AMPK)/glycogen synthase kinase 3β (GSK3β)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in vivo. In addition, the AMPK/GSK3β/Nrf2 pathway participated in the regulation of glutathione peroxidase 4 (GPX4) expression, and silencing of Nrf2 attenuated the effect of Bri on H/R-induced cell injury.Discussion and conclusionsBri protected against ferroptosis-mediated MIR damage by upregulating GPX4 through activation of the AMPK/GSK3β/Nrf2 signalling, suggesting that Bri might become a novel therapeutic agent for MIR.     

Catalpol counteracts the pathology in a mouse model of Duchenne muscular dystrophy by inhibiting the TGF-β1/TAK1 signaling pathway

Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disease caused by a mutation in the gene encoding the dystrophin protein. Catalpol is an iridoid glycoside found in Chinese herbs with anti-inflammatory, anti-oxidant, anti-apoptotic, and hypoglycemic activities that can protect against muscle wasting. In the present study we investigated the effects of catalpol on DMD. Aged Dystrophin-deficient (mdx) mice (12 months old) were treated with catalpol (100, 200 mg·kg⁻¹·d⁻¹, ig) for 6 weeks. At the end of the experiment, the mice were sacrificed, and gastrocnemius (GAS), tibialis anterior (TA), extensor digitorum longus (EDL), soleus (SOL) muscles were collected. We found that catalpol administration dose-dependently increased stride length and decreased stride width in Gait test. Wire grip test showed that the time of wire grip and grip strength were increased. We found that catalpol administration dose-dependently alleviated skeletal muscle damage, evidenced by reduced plasma CK and LDH activity as well as increased the weight of skeletal muscles. Catalpol administration had no effect on dystrophin expression, but exerted anti-inflammatory effects. Furthermore, catalpol administration dose-dependently decreased tibialis anterior (TA) muscle fibrosis, and inhibited the expression of TGF-β1, TAK1 and α-SMA. In primary myoblasts from mdx mice, knockdown of TAK1 abolished the inhibitory effects of catalpol on the expression levels of TGF-β1 and α-SMA. In conclusion, catalpol can restore skeletal muscle strength and alleviate skeletal muscle damage in aged mdx mice, thus may provide a novel therapy for DMD. Catalpol attenuates muscle fibrosis by inhibiting the TGF-β1/TAK1 signaling pathway.     

PTPL1 suppresses lung cancer cell migration via inhibiting TGF-β1-induced activation of p38 MAPK and Smad 2/3 pathways and EMT

Epithelial-mesenchymal transition (EMT) enables dissemination of neoplastic cells and onset of distal metastasis of primary tumors. However, the regulatory mechanisms of EMT by microenvironmental factors such as transforming growth factor-β (TGF-β) remain largely unresolved. Protein tyrosine phosphatase L1 (PTPL1) is a non-receptor protein tyrosine phosphatase that plays a suppressive role in tumorigenesis of diverse tissues. In this study we investigated the role of PTPL1/PTPN13 in metastasis of lung cancer and the signaling pathways regulated by PTPL1 in terms of EMT of non-small cell lung cancer (NSCLC) cells. We showed that the expression of PTPL1 was significantly downregulated in cancerous tissues of 23 patients with NSCLC compared with adjacent normal tissues. PTPL1 expression was positively correlated with overall survival of NSCLC patients. Then we treated A549 cells in vitro with TGF-β1 (10 ng/mL) and assessed EMT. We found that knockdown of PTPL1 enhanced the migration and invasion capabilities of A549 cells, through enhancing TGF-β1-induced EMT. In nude mice bearing A549 cell xenografts, knockdown of PTPL1 significantly promoted homing of cells and formation of tumor loci in the lungs. We further revealed that PTPL1 suppressed TGF-β-induced EMT by counteracting the activation of canonical Smad2/3 and non-canonical p38 MAPK signaling pathways. Using immunoprecipitation assay we demonstrated that PTPL1 could bind to p38 MAPK, suggesting that p38 MAPK might be a direct substrate of PTPL1. In conclusion, these results unravel novel mechanisms underlying the regulation of TGF-β signaling pathway, and have implications for prognostic assessment and targeted therapy of metastatic lung cancer.     

Ginsenoside Rg1 prevents acetaminophen-induced oxidative stress and apoptosis via Nrf2/ARE signaling pathway

Inappropriate use of acetaminophen (APAP) can lead to morbidity and mortality secondary to hepatic necrosis. Ginsenoside Rg1 is a major active ingredient in processed Panax ginseng, which is proved to elicit biological effects. We hypothesized the beneficial effect of Rg1 on APAP-mediated hepatotoxicity was through Nrf2/ARE pathway. The study was conducted in cells and mice, comparing the actions of Rg1. Rg1 significantly improved cell survival rates and promoted the expression of antioxidant proteins. Meanwhile, Rg1 reduced the excessive ROS and the occurrence of cell apoptosis, which were related to Nrf2/ARE pathway. Expression of Nrf2 has a certain cell specificity.

     

Fasudil alleviates brain damage in rats after carbon monoxide poisoning through regulating neurite outgrowth inhibitor/oligodendrocytemyelin glycoprotein signalling pathway

Carbon monoxide (CO) poisoning can lead to many serious neurological symptoms. Currently, there are no effective therapies for CO poisoning. In this study, rats exposed to CO received hyperbaric oxygen therapy, and those in the Fasudil group were given additional Fasudil injection once daily. We found that the escape latency in CO poisoning group (CO group) was significantly prolonged, the T₁/T_total was obviously decreased, and the mean escape time and the active escape latency were notably extended compared with those in normal control group (NC group, P < 0.05). After administration of Fasudil, the escape latency was significantly shortened, T₁/T_total was gradually increased as compared with CO group (>1 week, P < 0.05). Ultrastructural damage of neurons and blood‐brain barrier of rats was serious in CO group, while the structural and functional integrity of neuron and mitochondria maintained relatively well in Fasudil group. Moreover, we also noted that the expressions of neurite outgrowth inhibitor (Nogo), oligodendrocyte‐myelin glycoprotein (OMgp) and Rock in brain tissue were significantly increased in CO group, and the elevated levels of the three proteins were still observed at 2 months after CO poisoning. Fasudil markedly reduced their expressions compared with those of CO group (P < 0.05). In summary, the activation of Nogo‐OMgp/Rho signalling pathway is associated with brain injury in rats with CO poisoning. Fasudil can efficiently down‐regulate the expressions of Nogo, OMgp and Rock proteins, paving a way for the treatment of acute brain damage after CO poisoning.     

miR-7/TGF-β2 axis sustains acidic tumor microenvironment-induced lung cancer metastasis

Acidosis, regardless of hypoxia involvement, is recognized as a chronic and harsh tumor microenvironment (TME) that educates malignant cells to thrive and metastasize. Although overwhelming evidence supports an acidic environment as a driver or ubiquitous hallmark of cancer progression, the unrevealed core mechanisms underlying the direct effect of acidification on tumorigenesis have hindered the discovery of novel therapeutic targets and clinical therapy. Here, chemical-induced and transgenic mouse models for colon, liver and lung cancer were established, respectively. miR-7 and TGF-β2 expressions were examined in clinical tissues (n = 184). RNA-seq, miRNA-seq, proteomics, biosynthesis analyses and functional studies were performed to validate the mechanisms involved in the acidic TME-induced lung cancer metastasis. Our data show that lung cancer is sensitive to the increased acidification of TME, and acidic TME-induced lung cancer metastasis via inhibition of miR-7-5p. TGF-β2 is a direct target of miR-7-5p. The reduced expression of miR-7-5p subsequently increases the expression of TGF-β2 which enhances the metastatic potential of the lung cancer. Indeed, overexpression of miR-7-5p reduces the acidic pH-enhanced lung cancer metastasis. Furthermore, the human lung tumor samples also show a reduced miR-7-5p expression but an elevated level of activated TGF-β2; the expressions of both miR-7-5p and TGF-β2 are correlated with patients’ survival. We are the first to identify the role of the miR-7/TGF-β2 axis in acidic pH-enhanced lung cancer metastasis. Our study not only delineates how acidification directly affects tumorigenesis, but also suggests miR-7 is a novel reliable biomarker for acidic TME and a novel therapeutic target for non-small cell lung cancer (NSCLC) treatment. Our study opens an avenue to explore the pH-sensitive subcellular components as novel therapeutic targets for cancer treatment.KEY WORDS: Acidic tumor microenvironment, miR-7-5p, TGF-β2, Metastasis, Lung cancer, pH, Invasion     

丹参多酚酸盐通过TGF-β1/Smad和PI3K/AKT/mTOR信号通路抑制大鼠肝纤维化的进展

目的：探索丹参多酚酸盐对四氯化碳诱导的大鼠肝纤维化的防治作用及其作用机制。方法：将雄性SD大鼠随机分为正常对照组（空白组）、CCl₄模型组（模型组）、丹参多酚酸盐低剂量组（低剂量组）和丹参多酚酸盐高剂量组（高剂量组）,每组12只。采用1 mL·kg^-1每周2次的剂量给予大鼠灌胃CCl₄-橄榄油（1：1）溶液诱导建立肝纤维化模型,治疗组大鼠在建模的同时分别每日1次腹腔注射丹参多酚酸盐15,30 mg·kg^-1。7周处死大鼠,观察大鼠肝脏大体形态;HE和Masson三色染色检测肝组织病理学变化;全自动生化分析仪检测大鼠肝功能指标,包括总胆红素（TBIL）、谷草转氨酶（AST）及谷丙转氨酶（ALT）;放射免疫法测定四项肝纤维化指标,包括透明质酸（HA）、层黏蛋白（LN）、Ⅲ型前胶原肽（PⅢP）和Ⅳ型胶原（CIV）;实时定量PCR法测定肝组织中α-SMA、MMP-1、TIMP-1、Collagen Ⅰ和Collagen Ⅲ基因表达的水平;Western blot检测肝脏组织中TGF-β1、Smad2/3、Smad7、p-PI3K、p-AKT、p-mTOR等蛋白的表达。结果：与模型组相比,丹参多酚酸盐能够显著降低大鼠肝功能和肝纤维化指标,并改善大鼠肝纤维化程度;与此同时,丹参多酚酸盐能够抑制肝组织中TGF-β1/Smad和PI3K/AKT/mTOR信号通路,且能够通过调节细胞外基质的合成和降解来抑制肝纤维化的进展。结论：丹参多酚酸盐可通过调节TGF-β1/Smad和PI3K/AKT/mTOR信号通路发挥抗肝纤维化的作用。     

Neogambogic acid relieves myocardial injury induced by sepsis via p38 MAPK/NF-κB pathway

Sepsis-associated myocardial injury, an invertible myocardial depression, is a common complication of sepsis. Neogambogic acid is an active compound in garcinia and exerts anthelmintic, anti-inflammatory, and detoxification properties. The role of neogambogic acid in sepsis-associated myocardial injury was assessed. Firstly, mice were pretreated with neogambogic acid and then subjected to lipopolysaccharide treatment to induce sepsis. Results showed that lipopolysaccharide treatment induced up-regulation of biomarkers involved in cardiac injury, including lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB), and troponin I (cTnI). However, pretreatment with neogambogic acid reduced levels of LDH, CK-MB, and cTnI, and ameliorated histopathological changes in the heart tissues of septic mice. Secondly, neogambogic acid also improved cardiac function in septic mice through reduction in left ventricular end-diastolic pressure, and enhancement of ejection fraction, fractional shortening, and left ventricular systolic mean pressure. Moreover, neogambogic acid suppressed cardiac apoptosis and inflammation in septic mice and reduced cardiac fibrosis. Lastly, protein expression of p-p38, p-JNK, and p-NF-κB in septic mice was decreased by neogambogic acid. In conclusion, neogambogic acid exerted anti-apoptotic, anti-fibrotic, and anti-inflammatory effects in septic mice through the inactivation of MAPK/NF-κB pathway.     

Ginsenoside Rg1 protects dopaminergic neurons in a rat model of Parkinson's disease through the IGF-I receptor signalling pathway

Background and purpose:

We have shown that ginsenoside Rg1 is a novel class of potent phytoestrogen and activates insulin-like growth factor-I receptor (IGF-IR) signalling pathway in human breast cancer MCF-7 cells. The present study tested the hypothesis that the neuroprotective actions of Rg1 involved activation of the IGF-IR signalling pathway in a rat model of Parkinson''s disease, induced by 6-hydroxydopamine (6-OHDA).

Experimental approach:

Ovariectomized rats were infused unilaterally with 6-OHDA into the medial forebrain bundle to lesion the nigrostriatal dopamine pathway and treated with Rg1 (1.5 h after 6-OHDA injections) in the absence or presence of the IGF-IR antagonist JB-1 (1 h before Rg1 injections). The rotational behaviour induced by apomorphine and the dopamine content in the striatum were studied. Protein and gene expression of tyrosine hydroxylase, dopamine transporter and Bcl-2 in the substantia nigra were also determined.

Key results:

Rg1 treatment ameliorated the rotational behaviour induced by apomorphine in our model of nigrostriatal injury. This effect was partly blocked by JB-1. 6-OHDA significantly decreased the dopamine content of the striatum and treatment with Rg1 reversed this decrease. Treatment with Rg1 of 6-OHDA-lesioned rats reduced neurotoxicity, as measured by tyrosine hydroxylase, dopamine transporter and Bcl-2 protein and gene level in the substantia nigra. These effects were abolished by JB-1.

Conclusions and implications:

These data provide the first evidence that Rg1 has neuroprotective effects on dopaminergic neurons in the 6-OHDA model of nigrostriatal injury and its actions might involve activation of the IGF-IR signalling pathway.     

人参皂苷Rg1可能通过CDK4-pRB-E2F1通路减少神经元凋亡

目的　探讨人参皂苷Rg1是否通过CDK4 pRB E2F1通路对抗Aβ1～ 4 0 诱导的神经元凋亡。方法　用TUNEL染色、DNA琼脂糖凝胶电泳方法观察神经元凋亡形态学和生化改变 ;免疫印迹方法检测细胞周期相关的周期依赖性激酶4(Cyclindependentkinase 4,CDK4)、磷酸化的视网膜神经胶质瘤蛋白 (Retinoblastomaprotein ,pRB)水平 ;RT PCR技术检测E2F1mRNA表达水平 ;荧光分光光度计法检测凋亡效应分子Caspase 3活力的变化。结果　人参皂苷Rg1预处理可降低Aβ1～ 4 0 诱导的大鼠皮层神经元的凋亡率 ;凋亡细胞特有的DNA梯形条带消失 ;CDK4、磷酸化pRB水平降低 ;E2F1基因表达下调 ;Caspase 3活力下降。结论　人参皂苷Rg1可通过抑制CDK4 pRB E2F1信号传导通路及Caspase 3的激活 ,减少Aβ1～ 4 0 诱导的大鼠皮层神经元凋亡。