Shi-feng Chu

Ginsenoside Rg1 attenuates okadaic acid induced spatial memory impairment by the GSK3β/tau signaling pathway and the Aβ formation prevention in rats.

Ginsenoside Rg1, one of the major active ingredients isolated from Panax Ginseng, has been shown notable neuroprotective effects in memory impairment animals. However, the role of ginsenoside Rg1 on cognition capacity damaged by neurofibrillary tangles (NFTs) is still poorly understood, and the underlying mechanism remain to be fully elucidated. Okadaic acid (OKA), a potent phosphatase inhibitor, often apply to imitate Alzheimers disease-like symptom damaged by neurofibrillary tangles, was used to investigate the effects of ginsenoside Rg1 on memory impairment and the related mechanisms in Sprague Dawley (SD) rats. The anti-dementic drug donepezil was used as a positive contrast. The results showed that OKA intracerebroventricular (i.c.v.) injection induced memory impairment, including changes in the ability of orientation navigate, spatial probe and relearning memory in behavioral test of Morris water maze (MWM). However, treatment with Rg1 and donepezil remarkably alleviated these changes. Also OKA treated rats showed memory impairment including increasing of phospho-tau, decreasing of phospho-GSK3β and the formation of β-amyloid in special brain regions, which were reversed by Rg1 (20 mg/kg) and donepezil (1 mg/kg) administration. All these indicating that ginsenoside Rg1 protects rats against OKA-induced neurotoxicity. The possible neuroprotective mechanism may be that Rg1 decreases OKA-induced memory impairment through GSK3β/tau signaling pathway and/or attenuating Aβ formation. Thus, these studies indicate that ginsenoside Rg1 might be a potential preventive drug for Alzheimers disease.

Nrf2 pathway activation contributes to anti-fibrosis effects of ginsenoside Rg1 in a rat model of alcohol- and CCl4-induced hepatic fibrosis.

Aim:To investigate the anti-fibrosis effects of ginsenoside Rg1 on alcohol- and CCl4-induced hepatic fibrosis in rats and to explore the mechanisms of the effects.Methods:Rats were given 6% alcohol in water and injected with CCl4 (2 mL/kg, sc) twice a week for 8 weeks. Rg1 (10, 20 and 40 mg/kg per day, po) was administered in the last 2 weeks. Hepatic fibrosis was determined by measuring serum biochemical parameters, HE staining, Massons trichromic staining, and hydroxyproline and α-SMA immunohistochemical staining of liver tissues. The activities of antioxidant enzymes, lipid peroxidation, and Nrf2 signaling pathway-related proteins (Nrf2, Ho-1 and Nqo1) in liver tissues were analyzed. Cultured hepatic stellate cells (HSCs) of rats were prepared for in vitro studies.Results:In the alcohol- and CCl4-treated rats, Rg1 administration dose-dependently suppressed the marked increases of serum ALT, AST, LDH and ALP levels, inhibited liver inflammation and HSC activation and reduced liver fibrosis scores. Rg1 significantly increased the activities of antioxidant enzymes (SOD, GSH-Px and CAT) and reduced MDA levels in liver tissues. Furthermore, Rg1 significantly increased the expression and nuclear translocation of Nrf2 that regulated the expression of many antioxidant enzymes. Treatment of the cultured HSCs with Rg1 (1 μmol/L) induced Nrf2 translocation, and suppressed CCl4-induced cell proliferation, reversed CCl4- induced changes in MDA, GPX, PCIII and HA contents in the supernatant fluid and α-SMA expression in the cells. Knockdown of Nrf2 gene diminished these actions of Rg1 in CCl4-treated HSCs in vitro.Conclusion:Rg1 exerts protective effects in a rat model of alcohol- and CCl4-induced hepatic fibrosis via promoting the nuclear translocation of Nrf2 and expression of antioxidant enzymes.

Inhibitory effect of ginsenoside Rg1 on lipopolysaccharide-induced microglial activation in mice.

Microglial activation plays a pivotal role in the pathogenesis of neurodegenerative diseases by producing various pro-inflammatory cytokines and nitric oxide (NO). In the paper, the anti-inflammatory effect of ginsenoside Rg1 was investigated in mice intracerebroventricular injected of lipopolysaccharide (LPS). NO and tumor necrosis factor (TNF)-α production in both cerebral cortex and hippocampus decreased at dose-dependent manner by oral administration with Rg1. And the expression of ionized calcium binding adaptor molecule 1 (Iba-1) increased in both cerebral cortex and hippocampus in LPS-injected group compared to that in control group. However, Rg1 inhibited microglial activation by suppressing Iba-1 expression. In addition, the expression of inducible nitric oxide synthase (iNOS) was inhibited by Rg1. Moreover, Rg1 suppressed the phosphorylation level of IκB, nuclear translocation of p65 subunit of NFκB, and phosphorylation level of p38, ERK1/2, JNK mitogen-activated protein kinase (MAPK) induced by LPS. Concluding, Rg1 inhibited the inflammation mediated by LPS by suppressing NFκB and MAPK pathway, which provided the explanation for its therapeutic effect on neurodegenerative diseases.

Protective effect of (−)clausenamide against Aβ-induced neurotoxicity in differentiated PC12 cells

The neurotoxicity of aggregated beta-amyloid (Abeta) has been implicated as a critical cause in the pathogenesis of Alzheimers disease (AD). In the present study, we investigated the effect of (-)clausenamide ((-)Clau), an aqueous extract of leaves of Clausena lassium (lour) skeel, on the neurotoxicity of Abeta(25-35). The viability of differentiated PC12 cells was determined by MTT assay. Apoptosis was detected by flow cytometry. DCFH-DA was used for assessment of intracellular ROS generation, JC-1 and Rhodamine 123 for measurement of mitochondrial transmembrane potential (MMP). The intracellular calcium was determined with Fluo-3. The phosphorylation of p38 MAPK and the expression of Bcl-2, Bax, P53, Caspase 3 were examined by Western blot. The results showed that (-)Clau significantly elevated cell viability. Furthermore, (-)Clau arrested the apoptotic cascade by reversing overload of calcium, preventing ROS generation, moderated the dissipation of MMP and the misbalance of Bcl-2 and Bax, inhibiting the activation of p38 MAPK and the expression of P53 and cleaved Caspase 3. Our results suggested that (-)Clau may be a therapeutic agent for AD.

Protopanaxtriol protects against 3-nitropropionic acid-induced oxidative stress in a rat model of Huntington's disease

Aim:Protopanaxtriol (Ppt) is extracted from Panax ginseng Mayer. In the present study, we investigated whether Ppt could protect against 3-nitropropionic acid (3-NP)-induced oxidative stress in a rat model of Huntingtons disease (HD) and explored the mechanisms of action.Methods:Male SD rats were treated with 3-NP (20 mg/kg on d 1, and 15 mg/kg on d 2–5, ip). The rats received Ppt (5, 10, and 20 mg/kg, po) daily prior to 3-NP administration. Nimodipine (12 mg/kg, po) or N-acetyl cysteine (NAC, 100 mg/kg, po) was used as positive control drugs. The body weight and behavior were monitored within 5 d. Then the animals were sacrificed, neuronal damage in striatum was estimated using Nissl staining. Hsp70 expression was detected with immunohistochemistry. Reactive oxygen species (ROS) generation was measured using dihydroethidium (DHE) staining. The levels of components in the Nrf2 pathway were measured with immunohistochemistry and Western blotting.Results:3-NP resulted in a marked reduction in the body weight and locomotion activity accompanied by progressive striatal dysfunction. In striatum, 3-NP caused ROS generation mainly in neurons rather than in astrocytes and induced Hsp70 expression. Administration of Ppt significantly alleviated 3-NP-induced changes of body weight and behavior, decreased ROS production and restored antioxidant enzymes activities in striatum. Moreover, Ppt directly scavenged free radicals, increased Nrf2 entering nucleus, and the expression of its downstream products heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidase 1 (NQO1) in striatum. Similar effects were obtained with the positive control drugs nimodipine or NAC.Conclusion:Ppt exerts a protective action against 3-NP-induced oxidative stress in the rat model of HD, which is associated with its anti-oxidant activity.

Effects of chronic mild stress on behavioral and neurobiological parameters - Role of glucocorticoid.

Major depression is thought to originate from maladaptation to adverse events, particularly when impairments occur in mood-related brain regions. Hypothalamus-pituitary-adrenal (HPA) axis is one of the major systems involved in physiological stress response. HPA axis dysfunction and high glucocorticoid concentrations play an important role in the pathogenesis of depression. In addition, astrocytic disability and dysfunction of neurotrophin brain-derived neurotrophin factor (BDNF) greatly influence the development of depression and anxiety disorders. Therefore, we investigated whether depressive-like and anxiety-like behaviors manifest in the absence of glucocorticoid production and circulation in adrenalectomized (ADX) rats after chronic mild stress (CMS) exposure and its potential molecular mechanisms. The results demonstrate that glucocorticoid-controlled rats showed anxiety-like behaviors but not depression-like behaviors after CMS. Molecular and cellular changes included the decreased BDNF in the hippocampus, astrocytic dysfunction with connexin43 (cx43) decreasing and abnormality in gap junction in prefrontal cortex (PFC). Interestingly, we did not find any changes in glucocorticoid receptor (GR) or its chaperone protein FK506 binding protein 51 (FKBP5) expression in the hippocampus or PFC in ADX rats subjected to CMS. In conclusion, the production and circulation of glucocorticoids are one of the contributing factors in the development of depression-like behaviors in response to CMS. In contrast, the effects of CMS on anxiety-like behaviors are independent of the presence of circulating glucocorticoids. Meanwhile, stress decreased GR expression and enhanced FKBP5 expression via higher glucocorticoid exposure. Gap junction dysfunction and changes in BDNF may be associated with anxiety-like behaviors.

20C, a bibenzyl compound isolated from Gastrodia elata, protects PC12 cells against rotenone-induced apoptosis via activation of the Nrf2/ARE/HO-1 signaling pathway

Aim:Our preliminary study shows that a bibenzyl compound isolated from Gastrodia elata, 2-[4-hydroxy-3-(4-hydroxybenzyl)benzyl]-4-(4-hydroxybenzyl)phenol (designated 20C), protects PC12 cells against H2O2-induced injury. In this study we investigated whether 20C exerted neuroprotective action in a cell model of Parkinsons disease.Methods:A cell model of Parkinsons disease was established in PC12 cells by exposure to rotenone (4 μmol/L) for 48 h. Cell viability and apoptosis were assessed, and intracellular ROS level and the mitochondrial membrane potential (MMP) were detected. The expression of apoptosis-related proteins Bax, Bcl-2, cytochrome c, cleaved caspase-3, and oxidative stress-related proteins Nrf2, HO-1 and NQO1 were examined using Western blotting. The mRNA levels of HO-1 and NQO1 were determined with RT-PCR. The nuclear translocation of Nrf2 was observed with immunofluorescence staining.Results:Treatment with rotenone significantly increased the number of apoptotic cells, accompanied by marked increases in the Bax/Bcl-2 ratio, cytochrome c release and caspase-3 activation. Rotenone also increased ROS accumulation, reduced MMP, and increased the nuclear translocation of Nrf2 as well as the mRNA and protein levels of the Nrf2 downstream target genes HO-1 and NQO1 in PC12 cells. Co-treatment with 20C (0.01–1 μmol/L) dose-dependently attenuated rotenone-induced apoptosis and oxidative stress in PC12 cells. Nrf2 knockdown by siRNA partially reversed the protective effects of 20C in rotenone-treated PC12 cells.Conclusion:The bibenzyl compound 20C protects PC12 cells from rotenone-induced apoptosis, at least in part, via activation of the Nrf2/ARE/HO-1 signaling pathway.

Anti-inflammatory effect of IMMLG5521, a coumarin derivative, on Sephadex-induced lung inflammation in rats

The study is to investigate the effect of compound IMMLG5521, a coumarin derivative, on lung inflammation induced by Sephadex in rats. Sephadex led to massive granulomas, infiltration of neutrophils and eosinophils, the increase of TNF-α level in BALF and lung tissue. Sephadex injection led to the up-regulation of VCAM-1 and ICAM-1 expressions in the lungs. However, pretreatment with IMMLG5521 (6.25 and 12.5 mg/kg) inhibited massive granulomas and infiltration of neutrophils and eosinophils, decreased TNF-α level in BALF and lung tissue, and down-regulated VCAM-1 and ICAM-1 expressions in the lung tissue. In conclusion, compound IMMLG5521 may suppress the lung injury induced by Sephadex, at least in part, due to the prevention of the up-regulation of VCAM-1 and ICAM-1 expressions and TNF-α level.

Upregulating the Expression of Survivin-HBXIP Complex Contributes to the Protective Role of IMM-H004 in Transient Global Cerebral Ischemia/Reperfusion.

IMM-H004, a 3-piperazinylcoumarin compound derived from coumarin, has been proved effective against CA1 cell loss and spatial learning impairments resulting from transient global ischemia/reperfusion (TGCI/R), while the mechanism is still largely unknown. Here, we confirmed that treatment of rats with IMM-H004 immediately after TGCI/R ameliorated delayed neuronal death (DND) in the CA1 of hippocampus and cortex. Further study suggested that IMM-H004 contributed to the expression of antiapoptotic protein survivin through the activation of PI3K-dependent protein kinase B (PKB/Akt), which led to the phosphorylation of forkhead box O1 (FoxO1), then relieved the inhibiting effect on survivin promoter. Additionally, IMM-H004 also enhanced the expression of hepatitis B X-interacting protein (HBXIP), which formed a complex with survivin to prevent the activation of caspase death cascade, thereby halting apoptotic cell death. Finally, we injected a HBXIP siRNA into hippocampus and performed microelectroporation before ischemia/reperfusion, which abolished the protective effect of IMM-H004. Further study revealed that HBXIP maintained the high expression of Akt and survivin. Collectively, our findings demonstrated that DND after TGCI/R was alleviated by IMM-H004 through promoting the formation of survivin-HBXIP complex, which further emphasized the importance of endogenous protein involved in self-repair after stroke.

Piperine prevents cholesterol gallstones formation in mice

Biliary cholesterol may contribute to the formation of cholesterol gallstones, and regulation of these levels could be a useful therapeutic strategy for gallstones disease. Piperine (PA) is a potential cholesterol lowering agent. In this study, we assessed the effect and mechanism of PA in preventing cholesterol gallstones formation induced by feeding lithogenic diet containing high cholesterol levels to mice. C57BL/6 inbred mice were fed lithogenic or chow diets for 10 weeks, with or without PA (15, 30 and 60 mg/kg) or ursodeoxycholic acid (UDCA, 60 mg/kg) administration. Cholesterol, phospholipids and crystals in bile, the lipid in serum, pathological changes and proteins expression in liver were analyzed. The results showed that PA could decrease the cholesterol potency and crystals in bile, reduce total cholesterol (TC), triglycerides (TG) and increase high-density lipoprotein/low-density lipoprotein (HDL/LDL) levels in serum. Furthermore, PA treatment reduced liver lipid peroxidation and protected hepatobiliary cells from liver injury by decreasing malondialdehyde (MDA) and increasing superoxide dismutase (SOD). In addition, PA inhibited the expression of ATP-binding cassette transporters G5/8 (ABCG5/8) and liver X receptor (LXR) in liver, and reduced cholesterol transport from the hepatocytes to the gallbladder. It may be the mechanism of PA in preventing cholesterol gallstones formation. PA as a potential drug for prevention cholesterol gallstones merits further investigation.