Da-xiang Lu

Berberine Inhibits Doxorubicin-Triggered Cardiomyocyte Apoptosis via Attenuating Mitochondrial Dysfunction and Increasing Bcl-2 Expression

Cardiomyocyte apoptosis is an important event in doxorubicin (DOX)-induced cardiac injury. The aim of the present study was to investigate the protection of berberine (Ber) against DOX- triggered cardiomyocyte apoptosis in neonatal rat cardiomyocytes and rats. In neonatal rat cardiomyocytes, Ber attenuated DOX-induced cellular injury and apoptosis in a dose-dependent manner. However, Ber has no significant effect on viability of MCF-7 breast cancer cells treated with DOX. Ber reduced caspase-3 and caspase-9, but not caspase-8 activity in DOX-treated cardiomyocytes. Furthermore, Ber decreased adenosine monophosphate-activated protein kinase α (AMPKα) and p53 phosphorylation at 2 h, cytosolic cytochrome c and mitochondrial Bax levels and increased Bcl-2 level at 6 h in DOX-stimulated cardiomyocytes. Pretreatment with compound C, an AMPK inhibitor, also suppressed p53 phosphorylation and apoptosis in DOX-treated cardiomyocytes. DOX stimulation for 30 min led to a loss of mitochondrial membrane potential and a rise in the AMP/ATP ratio. Ber markedly reduced DOX-induced mitochondrial membrane potential loss and an increase in the AMP/ATP ratio at 1 h and 2 h post DOX exposure. In in vivo experiments, Ber significantly improved survival, increased stroke volume and attenuated myocardial injury in DOX-challenged rats. TUNEL and Western blot assays showed that Ber not only decreased myocardial apoptosis, caspase-3 activation, AMPKα and p53 phosphorylation, but also increased Bcl-2 expression in myocardium of rats exposed to DOX for 84 h. These findings indicate that Ber attenuates DOX-induced cardiomyocyte apoptosis via protecting mitochondria, inhibiting an increase in the AMP/ATP ratio and AMPKα phosphorylation as well as elevating Bcl-2 expression, which offer a novel mechanism responsible for protection of Ber against DOX-induced cardiomyopathy.

Neutral sulfate berberine modulates cytokine secretion and increases survival in endotoxemic mice

AbstractAim:Berberine is thought to be an immunomodulator, so the present study aimed to investigate the effect of berberine on mortality, lung and intestine injury in endotoxemic mice, and the mechanism of its action.Methods:Mice were challenged with lipopolysaccharide (LPS, 28 mg/kg, ip), and neutral sulfate berberine was administrated intragastrically. Mortality was monitored every 12 h, and histology of the lungs and intestine as well as the plasma tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-12 (IL-12), IL-10, and nitric oxide (NO) levels were examined.Results:Pretreatment with 50 mg/kg neutral sulfate berberine once a day for 5 days significantly decreased the mortality rate and attenuated tissue injury of the lungs and small intestine in mice challenged with LPS. LPS stimulated a marked increase in plasma levels of TNF-α, IFN-γ, IL-12, IL-10, and NO. The administration of berberine significantly reduced plasma TNF-α, IFN-γ, and NO levels, but did not suppress plasma IL-12 levels in mice exposed to LPS. Furthermore, pretreatment with neutral sulfate berberine augmented IL-10 secretion stimulated by LPS in mice.Conclusion:Pretreatment with neutral sulfate berberine attenuates tissue injury and improves survival in endotoxemic mice, which may be mediated, at least in part, by the inhibition of pro-inflammatory mediator production and upregulation of IL-10 release. These findings might provide a new strategy for the treatment of endotoxemia.

Berberine protects against lipopolysaccharide-induced intestinal injury in mice via alpha 2 adrenoceptor-independent mechanisms.

Aim:To investigate the mechanisms responsible for the protective action of berberine (Ber) against gut damage in endotoxemic mice.Methods:Male BALB/c mice were administered intragastrically with distilled water (0.1 mL/10 g), Ber (50 mg/kg) alone, yohimbine (2 mg/kg) alone, or Ber (50mg/kg) in combination with yohimbine (2 mg/kg) for 3 d. On the third day, lipopolysaccharide (LPS, 18 mg/kg) or normal saline was intraperitoneally injected one hour after the intragastric administration. Following the treatment, intestinal injury in the ileum was histopathologically accessed; enterocyte apoptosis was examined using TUNEL method; Toll-like receptor 4 (TLR4) mRNA expression was measured using RT-PCR assay; inhibitor protein-κBα (I-κBα) phosphorylation and myeloperoxidase content were examined using Western blloting. The macrophage inflammatory protein-2 (MIP-2) production was measured using ELISA assay.Results:Mice challenged with LPS caused extensive ileum injury, including a significantly increased injury score, decreased intestinal villus height, reduced gut mucosal weight and increased intestinal permeability. Furthermore, LPS significantly induced enterocyte apoptosis, increased TLR4 mRNA expression, I-κBα phosphorylation, MIP-2 production and myeloperoxidase content in the ileum. Pretreatment with Ber significantly alleviated all the alterations in the ileum in the endotoxemic mice. Pretreatment with the α2-adrenoceptor antagonist yohimbine did not block the protective action of Ber against LPS-induced intestinal injury. In addition, treatment with yohimbine alone did not prevent LPS-induced intestinal injury.Conclusion:Pretreatment with Ber provides significant protection against LPS-induced intestinal injury in mice, via reducing enterocyte apoptosis, inhibiting the TLR4-nuclear factor κB-MIP-2 pathway and decreasing neutrophil infiltration that are independent of α2-adrenoceptors.

Effects of neutral sulfate berberine on LPS-induced cardiomyocyte TNF-α secretion, abnormal calcium cycling, and cardiac dysfunction in rats

AbstractAim:To evaluate the effect of neutral sulfate berberine on cardiac function, tumor necrosis factor α (TNF-α) release, and intracellular calcium concentration ([Ca2+]i) in cardiomyocytes exposed to lipopolysaccharide (LPS).Methods:Primary cultured rat cardiomyocytes were prepared from ventricles of 3–4-day old Sprague- Dawley rats. TNF-α concentrations in cell-conditioned media were measured by using a Quantikine enzyme-linked immunosorbent assay kit, and cardiomyocyte [Ca2+]i was measured by using Fura-2/AM. The isolated rat hearts were perfused in the Langendorff mode.Results:LPS at doses of 1, 5, 10, and 20 μg/mL markedly stimulated TNF-α secretion from cardiomyocytes, and neutral sulfate berberine inhibited LPS-induced TNF-α production. Intracellular calcium concentration was significantly decreased after LPS stimulation for 1 h, and increased 2 h after LPS treatment. Pretreatment with neutral sulfate berberine reversed the LPS-induced [Ca2+]i alterations, although neutral sulfate berberine did not inhibit a rapid increase in cardiomyocyte [Ca2+]i induced by LPS. Perfusion of isolated hearts with LPS (100 μg/mL) for 20 min resulted in significantly impaired cardiac performance at 120 min after LPS challenge: the maximal rate of left ventricular pressure rise and fall (±dp/dtmax) decreased compared with the control. In contrast, ±dp/dtmax at 120 min in hearts perfused with neutral sulfate berberine (1 μmol/L) for 10 min followed by 20 min LPS (100 μg/mL) was greater than the corresponding value in the LPS group.Conclusion:Neutral sulfate berberine inhibits LPS-stimulated myocardial TNF-α production, impairs calcium cycling, and improves LPS-induced contractile dysfunction in intact heart.

Therapeutic strategies targeting the LPS signaling and cytokines

Lipopolysaccharide (LPS) has been recognized as a major player in the pathogenesis of sepsis and neutralization of LPS or inhibition of its signal transduction mechanism is promising new treatment strategy in preclinical experiments. However, these therapeutic approaches have been shown unsuccessful in clinical trials. LPS activates Toll-like receptor 4 (TLR4) and induces pro-inflammatory and anti-inflammatory responses, the altered innate and adaptive immune responses eventually lead to the immunosuppressive state. The future therapeutic efforts in sepsis should focus on the immunosuppressive state. In this article, we will outline the current data on therapeutic strategies targeting LPS, TLR4 and single cytokine in sepsis and discuss the experimental and clinical evaluation of the immunomodulatory action of glycine and berberine. While we have demonstrated berberine in combination with yohimbine can modulate host immune responses in endotoxemia, it seems worthwhile to conduct clinical trials on the safe and efficacy of this new immunomodulatory therapy.

β1-adrenoceptor stimulation promotes LPS-induced cardiomyocyte apoptosis through activating PKA and enhancing CaMKII and IκBα phosphorylation

IntroductionCaspase activation and cardiomyocyte apoptosis have been implicated in lipopolysaccharide (LPS)-induced cardiac contractile dysfunction. We have recently demonstrated that β1-adrenoceptor (AR) activation by endogenous norepinephrine contributes to cardiomyocyte apoptosis in endotoxemic mice. Here, we further investigated the molecular mechanisms for the enhancing effect of β1-AR activation on LPS-induced cardiomyocyte apoptosis.MethodsThe adult mouse ventricular myocytes were exposed to LPS, dobutamine, protein kinase A (PKA) inhibitor or/and nifedipine, an L-type Ca2+ channel blocker. Male BALB/c mice were treated with LPS or/ and β1-AR antagonist, atenolol. Cardiomyocyte apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling (TUNEL) assay and apoptosis-associated molecules were detected.ResultsLPS induced apoptosis in adult mouse ventricular myocytes, dobutamine (DOB), a β1-AR agonist, promoted apoptosis, caspase-8, 9 and 3 activation and increased cytosolic Ca2+ concentration in LPS-challenged cardiomyocytes. DOB also up-regulated TNF-α expression, decreased Bcl-2 levels, promoted Bax translocation to mitochondria, mitochondrial membrane potential loss and cytochrome c release as well as IκBα, p38 MAPK, JNK and Ca2+/calmodulin-dependent protein kinase II (CaMKII) phosphorylation in LPS-treated cardiomyocytes. PKA inhibitor abolished the effects of DOB on caspase-9 activation, Bcl-2 levels as well as JNK and p38 MAPK phosphorylation, but not on IκBα phosphorylation, TNF-α expression and caspase-8 activation in LPS-stimulated cardiomyocytes. Pretreatment with nifedipine not only significantly blocked the enhancing effects of DOB on LPS-induced elevation in cytosolic Ca2+ concentration and CaMKII phosphorylation in cardiomyocytes, but also partly reversed the effects of DOB on caspase-9 and caspase-3/7 activities in LPS-treated cardiomyocytes. Furthermore, atenolol suppressed TNF-α expression, JNK, p38 MAPK and CaMKII phosphorylation, increased Bcl-2 expression, and inhibited cytochrome c release and cardiomyocyte apoptosis in the myocardium of endotoxemic mice.Conclusionsβ1-AR activation promotes LPS-induced apoptosis through activating PKA, increasing CaMKII phosphorylation as well as enhancing IκBα phosphorylation and TNF-α expression in cardiomyocytes.

Yohimbine Promotes Cardiac NE Release and Prevents LPS-Induced Cardiac Dysfunction via Blockade of Presynaptic α2A-Adrenergic Receptor

Myocardial depression is an important contributor to mortality in sepsis. We have recently demonstrated that α2-adrenoceptor (AR) antagonist, yohimbine (YHB), attenuates lipopolysaccharide (LPS)-induced myocardial depression. However, the mechanisms for this action of YHB are unclear. Here, we demonstrated that YHB decreased nitric oxide (NO) and tumor necrosis factor-alpha (TNF-α) levels in the myocardium and plasma, attenuated cardiac and hepatic dysfunction, but not kidney and lung injuries in endotoxemic mice. Immunohistochemical analysis revealed that cardiac α2A-AR was mostly located in sympathetic nerve presynaptic membrane; YHB decreased cardiac α2A-AR level and promoted cardiac norepinephrine (NE) release in endotoxemic mice. Reserpine that exhausted cardiac NE without markedly decreasing plasma NE level abrogated the inhibitory effects of YHB on cardiac TNF-α and iNOS expression as well as cardiac dysfunction, but not the suppressive effects of YHB on plasma TNF-α and NO elevation in LPS-challenged mice. Furthermore, both reserpine and YHB significantly inhibited LPS-induced myocardial apoptosis. α1-AR, β2-AR, but not β1-AR antagonists reversed the inhibitory effect of YHB on LPS-stimulated myocardial apoptosis. However, β1-AR antagonist attenuated LPS-caused cardiomyocyte apoptosis, partly abolished the protective effect of YHB on the left ventricular ejection fraction in endotoxemic mice. Altogether, these findings indicate that YHB attenuates LPS-induced cardiac dysfunction, at least in part, through blocking presynaptic α2A-AR and thus increasing cardiac NE release. YHB-elevated cardiac NE improves cardiac function via suppressing cardiac iNOS and TNF-α expression, activating β1-AR and inhibiting cardiomyocyte apoptosis through α1- and β2-AR in endotoxemic mice. However, cardiac β1-AR activation promotes LPS-induced cardiomyocyte apoptosis.

Glycine inhibits the LPS-induced increase in cytosolic Ca 2+ concentration and TNFα production in cardiomyocytes by activating a glycine receptor

AbstractAim:Previous studies have demonstrated that glycine (GLY) markedly reduces lipopolysaccharide (LPS)-induced myocardial injury. However, the mechanism of this effect is still unclear. The present study investigated the effect of GLY on cytosolic calcium concentration ([Ca2+]c) and tumor necrosis factor-α (TNFα) production in cardiomyocytes exposed to LPS, as well as whether the glycine-gated chloride channel is involved in this process.Methods:Neonatal rat cardiomyocytes were isolated, and the [Ca2+]c and TNFα levels were determined by using Fura-2 and a Quantikine enzyme-linked immunosorbent assay, respectively. The distribution of the GLY receptor and GLY-induced currents in cardiomyocytes were also investigated using immunocytochemistry and the whole-cell patch-clamp technique, respectively.Results:LPS at concentrations ranging from 10 ng/mL to 100 μg/mL significantly stimulated TNFα production. GLY did not inhibit TNFα production induced by LPS at concentrations below 10 ng/mL but did significantly decrease TNFα release stimulated by 100 μg/mL LPS and prevented an LPS-induced increase in [Ca2+]c, which was reversed by strychnine, a glycine receptor antagonist. GLY did not block the isoproterenol-induced increase in [Ca2+]c, but did prevent the potassium chloride-induced increase in [Ca2+]c in cardiomyocytes. Strychnine reversed the inhibition of the KCl–stimulated elevation in [Ca2+]c by GLY. In chloride-free buffer, GLY had no effect on the dipotassium hydrogen phosphate-induced increase in [Ca2+]c. Furthermore, GLY receptor α1 and β subunit-immunoreactive spots were observed in cardiomyocytes, and GLY-evoked currents were blocked by strychnine.Conclusion:Cardiomyocytes possess the glycine-gated chloride channel, through which GLY prevents the increase in [Ca2+]c and inhibits the TNFα production induced by LPS at high doses in neonatal rat cardiomyocytes.

Neuroprotective Effect of Lutein on NMDA-Induced Retinal Ganglion Cell Injury in Rat Retina

AbstractLutein injection is a possible therapeutic approach for retinal diseases, but the molecular mechanism of its neuroprotective effect remains to be elucidated. The aim of this study was to investigate its protective effects in retinal ganglion cells (RGCs) against N-methyl-d-aspartate (NMDA)-induced retinal damage in vivo. Retinal damage was induced by intravitreal NMDA injection in rats. Each animal was given five daily intraperitoneal injections of Lutein or vehicle along with intravitreal NMDA injections. Electroretinograms were recorded. The number of viable RGCs was quantified using the retinal whole-mount method by immunofluorescence. Proteins were measured by Western blot assays. Lutein reduced the retinal damage and improved the response to light, as shown by an animal behavior assay (the black-and-white box method) in rats. Furthermore, Lutein treatment prevented the NMDA-induced reduction in phNR wave amplitude. Lutein increased RGC number after NMDA-induced retina damage. Most importantly, Bax, cytochrome c, p-p38 MAPK, and p–c-Jun were all upregulated in rats injected with NMDA, but these expression patterns were reversed by continuous Lutein uptake. Bcl-2, p-GSK-3β, and p-Akt in the Lutein-treated eyes were increased compared with the NMDA group. Lutein has neuroprotective effects against retinal damage, its protective effects may be partly mediated by its anti-excitability neurotoxicity, through MAPKs and PI3K/Akt signaling, suggesting a potential approach for suppressing retinal neural damage.

Berberine inhibits norepinephrine-induced apoptosis in neonatal rat cardiomyocytes via inhibiting ROS-TNF-α-caspase signaling pathway.

ObjectiveTo determine the effect of berberine (Ber) on norepinephrine (NE)-induced apoptosis in neonatal rat cardiomyocytes.MethodsThe cultured neonatal rat cardiomyocytes were treated with NE in the presence or absence of Ber. The activity of lactate dehydrogenase (LDH) in the culture medium was examined, and apoptosis of cardiomyocytes was assessed by Hoechst 33258, isothiocyanate (FITC)-conjugated annexin-V, and propidine iodide (PI) staining. In addition, the activities of caspases-2 and-3 were measured by a fluorescent assay kit. The level of secreted tumor necrosis factor α (TNF-α) and production of intracellular reactive oxygen species (ROS) were also determined.ResultsNE at a concentration of 50 μ mol/L induced an obvious increase in the activity of LDH in the culture medium (P<0.05), which was inhibited by coincubation with 0.5, 1.0, or 2.0 μ mol/L Ber (P<0.05). Ber also significantly attenuated NE-induced apoptosis in a dose-dependent manner (P<0.01). Moreover, Ber at a dose of 2 μ mol/L markedly decreased the ROS and TNF-α productions (P <0.05) and inhibited the activation of caspases-2 and -3 in cardiomyocytes exposed to NE (P<0.05)h.ConclusionThe present study suggested that Ber could reduce NE-induced apoptosis in neonatal rat cardiomyocytes through inhibiting the ROS-TNF-α-caspase signaling pathway.