Lithium ions attenuate serum-deprivation-induced apoptosis in PC12 cells through regulation of the Akt/FoxO1 signaling pathways

Qingxin Kaiqiao Fang decreases Tau hyperphosphorylation in Alzheimer's disease via the PI3K/Akt/GSK3β pathway in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Alzheimer's disease (AD) belongs to the category of "senile dementia" in traditional Chinese medicine. AD is associated with brain emptiness or collaterals blocked by phlegm-heat. "Fumanjian" from Jingyue Quanshu treats dementia by promoting qi circulation, alleviating depression, eliminating turbidity, cultivating positivity, and dispelling evil spirits. Qingxin Kaiqiao Fang (QKF), derived from Fumanjian, is effective in treating AD owing to previously mentioned clinical effects. Elucidating the mechanism(s) of action of QKF on AD associated with phlegm-heat may be beneficial for therapeutic management; however, further research is needed.

AIM OF THE STUDY

This study aimed to determine the role of the PI3K/Akt pathway in AD, especially the specific effector protein involved, and explore the efficacy of QKF in treating AD by modulating the PI3K/Akt signal.

MATERIALS AND METHODS

High-performance liquid chromatography-Q-orbitrap-mass spectrometry was used to analyze the chemical components of QKF. Subsequently, APP/PS1 double-transgenic mice were used for behavioral tests, and hematoxylin-eosin and Nissl staining were used to assess the neuroprotective and cognitive effects of QKF. Cerebrospinal fluid pharmacology was used in in vitro validation, and Aβ25-35 was used to induce PC12 cells to establish the AD cell model. Various methods, including immunohistochemistry, Western blotting, quantitative real-time polymerase chain reaction, morphological assay, cell counting kit-8(CCK-8) assay, and terminal deoxynucleotide transferase (TdT)-mediated dUTP nick-end labeling (TUNEL)staining, were used to evaluate the effect of QKF on Tau hyperphosphorylation and anti-apoptosis. These methods also assessed the influence of QKF on the PI3K/Akt/GSK3β pathway involving the mRNA and protein expressions. Finally, the inhibitor - LY294002 was used for reverse validation.

RESULTS

We identified 295 chemical components in the water extract of QKF.QKF improved spatial cognition and learning memory in APP/PS1 mice, protected PC12 cell morphology, improved cell survival, reduced Aβ25-35-induced apoptosis, and inhibited the hyperphosphorylation of Tau protein via the PI3k/Akt/GSK3β signaling pathway. Furthermore, this protective effect of QKF was reduced by LY294002 in vitro.

CONCLUSIONS

QKF can improve spatial cognition, learning, and memory abilities in APP/PS1 mice and protect PC12 cells. Decreasing the Tau hyperphosphorylation in AD exhibits curative efficacy on AD via the PI3K/Akt/GSK3β pathway in vitro and in vivo.

Comparison of Chemical Compositions and Antioxidant Activity of Essential Oils from Litsea Cubeba, Cinnamon, Anise, and Eucalyptus

The purpose of this study was to compare the antioxidant activity of litsea cubeba oil (LCO), cinnamon oil (CO), anise oil (AO), and eucalyptus oil (EUC) in vitro. The chemical compositions of the essential oils (EOs) were analyzed using gas chromatography-mass spectrometry (GC-MS). The antioxidant activity of the four EOs was evaluated through scavenging DPPH free radicals, chelating Fe²⁺, scavenging hydroxyl free radicals, and inhibiting yolk lipid peroxidation. The results showed that the major compounds found in LCO, CO, AO, and EUC are citral (64.29%), cinnamaldehyde (84.25%), anethole (78.51%), and 1,8-cineole (81.78%), respectively. The four EOs all had certain antioxidant activity. The ability to scavenge DPPH radical was ranked in the order of LCO > CO > AO > EUC. The hydroxyl radical scavenging ability was ranked in the order of EUC > CO > LCO > AO. The chelating Fe²⁺ capacity was ranked in the order of EUC > AO > CO > LCO. The yolk lipid peroxidation inhibition ability was ranked in the order of CO > AO > EUC > LCO. In different antioxidant activity assays, the antioxidant activity of the EOs was different. It was speculated that the total antioxidant activity of an EO may be the result of the joint action of different antioxidant capacities.

Lithium and hormesis: Enhancement of adaptive responses and biological performance via hormetic mechanisms

Biomedical and consumer interest in the health-promoting properties of pure single entities of known or unknown chemical constituents and mixtures has never been greater. Since its "rediscovery" in the 1950s, lithium is an example of such a constituent that represents an array of scientific and public health challenges and medical potentials that may now be understood best when seen through the lens of the dose-response paradigm known as hormesis. The present paper represents the first review of the capacity of lithium to induce hormetic dose responses in a broad range of biological models, organ systems, and endpoints. Of significance is that the numerous hormetic findings occur with extensive concentration/dose response evaluations with the optimal dosing being similar across multiple organ systems. The particular focus of these hormetic dose-response findings was targeted to research with a broad spectrum of stem cell types and neuroprotective effects. These findings suggest that lithium may have critically valuable systemic effects with respect to those therapeutically treated with lithium as well as for exposures that may be achieved via dietary intervention.

Hydroxysafflor Yellow A and Anhydrosafflor Yellow B Protect Against Cerebral Ischemia/Reperfusion Injury by Attenuating Oxidative Stress and Apoptosis via the Silent Information Regulator 1 Signaling Pathway

Hydroxysafflor yellow A (HSYA) and anhydrosafflor yellow B (AHSYB) are the main water-soluble compounds in Carthamus tinctorius L. However, studies on the effect of AHSYB on cerebral ischemia/reperfusion (I/R) injury and the therapeutic effect of HSYA by regulating silent information regulator 1 (SIRT1) pathway remain obscure. In this study, we investigated whether the neuroprotective effects of HSYA and AHSYB on oxygen-glucose deprivation/reoxygenation in primary-cultured hippocampal neuronal cells and the middle cerebral artery occlusion and reperfusion model in rats are associated with the regulation of the SIRT1 pathway. In vitro, HSYA and AHSYB increased cell viability, depressed oxidation properties, and reduced neuronal cell apoptosis. In vivo results showed that HSYA and AHSYB effectively reduced infarct volume, improved neurological function, suppressed apoptosis, and decreased the oxidative stress reaction. Besides, RT-PCR and Western blot analysis showed that HSYA and AHSYB increased the mRNA and protein expressions of the main factors in the SIRT1 pathway, including SIRT1, forkhead box O (FOXO) 1, and peroxisome proliferator–activated receptor coactivator 1α (PGC1α), decreased the expression of Bax, and increased the expression of Bcl-2. The results from immunohistochemistry also showed that the expressions of SIRT1, FOXO1, and PGC1α were increased after treatment with HSYA and AHSYB. Furthermore, the neuroprotective effects of HSYA and AHSYB were abolished by EX527 (SIRT1–specific inhibitor). These results indicated that HSYA and AHSYB should be developed into potential drugs for treating cerebral I/R injury via the SIRT1 pathway. Although HSYA and AHSYB have different chemical structures, both of them exert similar neuroprotective properties against I/R injury in vitro and in vivo, which means that AHSYB is also a non-negligible component in safflower.

PTEN mediates serum deprivation-induced cytotoxicity in H9c2 cells via the PI3K/AKT signaling pathway

The pathogenesis of acute myocardial infarction (AMI) is associated with cardiomyocyte necrosis and apoptosis. Numerous studies have determined the regulatory effects of Phosphatase and tensin homolog (PTEN) cell proliferation and apoptosis in other cell types. However, the potential role of PTEN in cardiomyocyte is unclear. In this study, we used H9c2 cells cultured under serum deprivation to simulate the apoptosis process of myocardial infarction. Small interference RNA (siRNA) of PTEN was used to knock down the expression of PTEN. Cell viability was determined by CCK-8. Cell proliferation was examined by Edu staining, and the protein expression was analyzed by Western blot. We also evaluated the generation of ROS, the degree of DNA damage, and cell apoptosis using immunofluorescence assay. As a result, we observed that serum deprivation in H9c2 cells increased PTEN expression. Functionally, the PTEN knockdown experiment using siRNA inhibited serum deprivation-induced cell apoptosis, ROS production, and DNA damage, whereas increased cell proliferation. All these effects could be reversed by phosphatidylinositol 3-kinase (PI3K) inhibitor, which indicated the PI3K/protein kinase B (AKT) might be the critical component of the PTEN effects during serum deficiency. In conclusion, our study indicated the role of the PTEN/PI3K/AKT pathway in serum deprivation-induced cytotoxicity in H9c2 cells.

Metformin protects PC12 cells and hippocampal neurons from H2 O 2 -induced oxidative damage through activation of AMPK pathway

Metformin, a first line anti type 2 diabetes drug, has recently been shown to extend lifespan in various species, and therefore, became the first antiaging drug in clinical trial. Oxidative stress due to excess reactive oxygen species (ROS) is considered to be an important factor in aging and related disease, such as Alzheimer's disease (AD). However, the antioxidative effects of metformin and its underlying mechanisms in neuronal cells is not known. In the present study, we showed that metformin, in clinically relevant concentrations, protected neuronal PC12 cells from H₂ O₂ -induced cell death. Metformin significantly ameliorated cell death due to H₂ O₂ insult by restoring abnormal changes in nuclear morphology, intracellular ROS, lactate dehydrogenase, and mitochondrial membrane potential induced by H₂ O₂ . Hoechst staining assay and flow cytometry analysis revealed that metformin significantly reduced the apoptosis in PC12 cells exposed to H₂ O₂ . Western blot analysis further demonstrated that metformin stimulated the phosphorylation and activation of AMP-activated protein kinase (AMPK) in PC12 cells, while application of AMPK inhibitor compound C, or knockdown of the expression of AMPK by specific small interfering RNA or short hairpin RNA blocked the protective effect of metformin. Similar results were obtained in primary cultured hippocampal neurons. Taken together, these results indicated that metformin is able to protect neuronal cells from oxidative injury, at least in part, via the activation of AMPK. As metformin is comparatively cheaper with much less side effects in clinic, our findings support its potential to be a drug for prevention and treatment of aging and aging-related diseases.

Statins induce cell apoptosis through a modulation of AKT/FOXO1 pathway in prostate cancer cells

Background

In recent years, statins have been frequently investigated in neoplasms. However, the potential roles of statins on prostate cancer cells and the underlying mechanisms have not been fully elucidated. In current study, we explored the effect and molecular mechanism of statins on cell proliferation and apoptosis in prostate cancer cells.

Methods

Prostate cancer cell were treated with gradient doses of simvastatin and fluvastatin for 24–72 h. Cell proliferation was analyzed by using MTS assay and colony formation. Cell apoptosis was measured by Hoechst staining, flow cytometry and caspase-3 activity. Western blotting was used to evaluate the proteins levels.

Results

Both simvastatin and fluvastatin produced a dose- and time-dependent inhibition of cell viability and colony formation while a promotion of cell apoptosis as evident with increases in caspase-3 activity, cleaved-caspase-3, cleaved-caspase-8 and cleaved-PARP levels in PC3 cells. Similar statin effects were observed in DU145 prostate cancer cells. Furthermore, statins produced a time- and dose-dependent reduction of phosphorylated-AKT and phosphorylated-FOXO1 levels in PC3 cells, and pretreatment of cells with an AKT phosphorylation inhibitor, MK2206, potentiated statins’ effect.

Conclusion

Statins decrease cell proliferation and induce cell apoptosis, probably mediated via a downregulation of AKT/FOXO1 phosphorylation in prostate cancer cells, which may have a potential benefit in prostate cancer prevention and therapy.

Effects of lithium on the secretory production of recombinant antibody from insect cells

Monoclonal antibodies and antibody fragments are widely used in therapeutics and diagnoses. While mammalian cells serve as the host cells for antibody production, insect cells can produce large quantities of secretory antibodies in serum-free suspension cultures. The effects of lithium on the processes of autophagy and apoptosis in mammalian cells are well chronicled. In the present study, stably transformed insect cells, which produce an engineered antibody molecule, were cultured with lithium chloride in a serum-free medium. Treatment with lithium chloride induced autophagy and apoptosis in recombinant insect cells and led to increases in the yields of secreted antibodies.

Combing metabolomics with bioanalysis methods to study the antitumor mechanism of the new acridone derivative 8q on CCRF-CEM cells: 8q induced mitochondrial-mediated apoptosis and targeted the PI3K/AKT/FOXO1 pathway

A novel acridone derivative, N-(2-(dimethylamino)ethyl)-1-((3-methoxybenzyl)amino)-5- nitro-9-oxo-9,10-dihydro-acridine-4-carboxamide (8q), which was synthesized in our lab, showed potent anti-leukaemia activity against CCRF-CEM cells. Moreover, in silico predictions showed that 8q conformed to the rule of five and displayed low toxicity. However, the mechanism of anti-leukaemia action remains unclear. The aim of this research was to reveal the probable anti-leukaemia mechanism of 8q on CCRF-CEM cells. Flow cytometry assay demonstrated that 8q induced apoptosis. The expression of caspase family proteins results showed that 8q could only promote cleaved caspase-3, 7 and 9 expressions without affecting cleaved caspase-8 protein, hinting that 8q induced mitochondrial-mediated apoptosis. Further, we detected 3 indicators of mitochondrial lesions, including increased of Cyt-C release, with a decrease in MMP and ATP levels. Next, metabolomics were introduced to assist in the research of the anti-leukaemia mechanism of 8q. The metabolomics results showed that 100 nM 8q could increase the level of GSH, and decrease its oxidation products. These indicated 8q could influence the ROS, which derived by mitochondria. Then we examined the effect of 8q on intracellular ROS levels. What is particularly interesting is that 8q inhibited cell ROS stress at low concentration and stimulated ROS stress at high concentration. The pro-apoptosis mechanisms of 8q were then explored. 8q significantly decreased anti-apoptotic proteins Bcl-2 and Bcl-xL expression, whereas it up-regulated the pro-apoptotic proteins Bax, Bak, Bad, Bik and Puma expression. In addition, 8q dramatically inhibited the expression of FASN, which is related to fatty acid metabolism. Furthermore, PI3K, AKT and FOXO1 were inactivated, and the expression of total AKT was also inhibited by 8q treatment, which promoted intrinsic apoptosis. In conclusion, these findings demonstrate that 8q can induce mitochondrial lesions and promote mitochondrial-mediated pathway apoptosis by regulating the expression of Bcl-2 family proteins and inhibiting the activity of the PI3K/AKT/FOXO1 signaling pathway.

Neuroprotective Effect of Tetrahedral DNA Nanostructures in a Cell Model of Alzheimer's Disease

Accumulating evidence supports the abnormal deposition of amyloid β-peptide (Aβ) as the main cause of Alzheimer's disease (AD). Therefore, fighting against the formation, deposition, and toxicity of Aβ is a basic strategy for the treatment of AD. In the process of in vitro nerve cell culture, screening out drugs that can antagonize a series of toxic reactions caused by β-amyloid deposition has become an effective method for the follow-up treatment of AD. Our previous studies showed that tetrahedral DNA nanostructures (TDNs) had good biocompatibility and had some positive effects on the biological behavior of cells. In this study, the main aim of our work was to explore the effects and potential mechanism of TDNs in protecting neuronal PC12 cells from the toxicity of Aβ. Our study demonstrated that TDNs can protect and rescue PC12 cell death through Aβ25-35-induced PC12 cell apoptosis. Further studies showed that TDNs significantly improved the apoptosis by affecting the abnormal cell cycle, restoring abnormal nuclear morphology and caspase activity. Western blot analysis showed that TDNs could prevent the damage caused by Aβ deposition by activating the ERK1/2 pathway and thus be a potential therapeutic agent with a neuroprotective effect in Alzheimer's disease. Our finding provides a potential application of TDNs in the prevention and treatment of AD.

αMSH prevents ROS-induced apoptosis by inhibiting Foxo1/mTORC2 in mice adipose tissue

Alpha-melanocyte stimulating hormone (αMSH) is an important adenohypophysis polypeptide hormone that regulates body metabolic status. To date, it is well known that the disorder of hypothalamic αMSH secretion is related to many metabolic diseases, such as obesity and type II diabetes. However, the underlying mechanisms are poorly understood. In our study, we focused on the reactive oxygen species (ROS)-induced adipocyte apoptosis and tried to unveil the role of αMSH in this process and the signal pathway which αMSH acts through. Kunming white mice were used and induced to oxidative stress status by hydrogen peroxide (H2O2) injection and a significant reduction of αMSH were found in mice serum, while elevated ROS level and mRNA level of pro-apoptotic genes were observed in mice adipose tissue. What is more, when detect the function of αMSH in ROS-induced apoptosis, similar inhibitory trend was found with the oxidative stress inhibitor N-acetyl-L-cysteine (NAC) in ROS-induced adipocyte apoptosis and this trend is αMSH receptor melanocortin 5 receptor (MC5R) depended, while an opposite trend was found between αMSH and Foxo1, which is a known positive regulator of adipocyte apoptosis. Further, we found that the repress effect of αMSH in adipocytes apoptosis is acting through Foxo1/mTORC2 pathway. These findings indicate that, αMSH has a strong inhibitory effect on ROS-induced adipocyte apoptosis and underlying mechanism is interacting with key factors in mTOR signal pathway. Our study demonstrated a great role of αMSH in adipocyte apoptosis and brings a new therapeutic mean to the treatment of obesity and diabetes.

H2O2 attenuates IGF-1R tyrosine phosphorylation and its survival signaling properties in neuronal cells via NR2B containing NMDA receptor

Impairment of insulin-like growth factor I (IGF-I) signaling plays an important role in the development of neurodegeneration. In the present study, we investigated the effect of H₂O₂ on the survival signaling of IGF-1 and its underlying mechanisms in human neuronal cells SH-SY5Y. Our results showed that IGF-1 promoted cell survival and stimulated phosphorylation of IGF-1R as well as its downstream targets like AKT and ERK1/2 in these cells. Meanwhile, these effects of IGF-1 were abolished by H₂O₂ at 200μM concentration which did not cause any significant toxicity to cells itself in our experiments. Moreover, studies using various glutamate receptor subtype antagonists displayed that N-methyl-D -aspartate (NMDA) receptor antagonist dizocilpine maleate (MK-801) blocked the effects of H₂O₂, whereas other glutamate receptor subtype antagonists, such as non-NMDA receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX), metabolic glutamate receptor antagonists LY341495 and CPCCOEt, had no effect. Further studies revealed that NR2B-containing NMDARs are responsible for these effects as its effects were blocked by pharmacological inhibitor Ro25-698 or specific siRNA for NR2B, but not NR2A. Finally, our data also showed that Ca²⁺ influx contributes to the effects of H₂O₂. Similar results were obtained in primary cultured cortical neurons. Taken together, the results from the present study suggested that H₂O₂ attenuated IGF-1R tyrosine phosphorylation and its survival signaling properties via NR2B containing NMDA receptors and Ca²⁺ influx in SH-SY5Y cells. Therefore, NMDAR antagonists, especially NR2B-selective ones, combined with IGF-1 may serve as an alternative therapeutic agent for oxidative stress related neurodegenerative disease.

Artemisinin protects PC12 cells against β-amyloid-induced apoptosis through activation of the ERK1/2 signaling pathway

Accumulating evidence displays that an abnormal deposition of amyloid beta-peptide (Aβ) is the primary cause of the pathogenesis of Alzheimer's disease (AD). And therefore the elimination of Aβ is regarded as an important strategy for AD treatment. The discovery of drug candidates using culture neuronal cells against Aβ peptide toxicity is believed to be an effective approach to develop drug for the treatment of AD patients. We have previously showed that artemisinin, a FDA-approved anti-malaria drug, has neuroprotective effects recently. In the present study, we aimed to investigate the effects and potential mechanism of artemisinin in protecting neuronal PC12 cells from toxicity of β amyloid peptide. Our studies revealed that artemisinin, in clinical relevant concentration, protected and rescued PC12 cells from Aβ25–35-induced cell death. Further study showed that artemisinin significantly ameliorated cell death due to Aβ25–35 insult by restoring abnormal changes in nuclear morphology, lactate dehydrogenase, intracellular ROS, mitochondrial membrane potential and activity of apoptotic caspase. Western blotting analysis demonstrated that artemisinin activated extracellular regulated kinase ERK1/2 but not Akt survival signaling. Consistent with the role of ERK1/2, preincubation of cells with ERK1/2 pathway inhibitor PD98059 blocked the effect of artemisinin while PI3K inhibitor LY294002 has no effect. Moreover, Aβ1-42 also caused cells death of PC12 cells while artemisinin suppressed Aβ1-42 cytotoxicity in PC12 cells. Taken together, these results, at the first time, suggest that artemisinin is a potential protectant against β amyloid insult through activation of the ERK1/2 pathway. Our finding provides a potential application of artemisinin in prevention and treatment of AD.

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β-amyloid induced apoptosis in PC12 cells.

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Artemisinin protected PC12 cells against β-amyloid-induced apoptosis.

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Artemisinin activated ERK1/2 signaling pathway in PC12 cells.

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Artemisinin protected PC12 cells against β-amyloid toxicity by ERK1/2 signaling pathway.

Palmitic acid triggers cell apoptosis in RGC-5 retinal ganglion cells through the Akt/FoxO1 signaling pathway

Hallmarks of the pathophysiology of glaucoma are oxidative stress and apoptotic death of retinal ganglion cells (RGCs). Lipotoxicity, involving a series of pathological cellular responses after exposure to elevated levels of fatty acids, leads to oxidative stress and cell death in various cell types. The phosphatidylinositol-3-kinase/protein kinase B/Forkhead box O1 (PI3K/Akt/FoxO1) pathway is crucial for cell survival and apoptosis. More importantly, FoxO1 gene has been reported to confer relatively higher risks for eye diseases including glaucoma. However, little information is available regarding the interaction between FoxO1 and RGC apoptosis, much less a precise mechanism. In the present study, immortalized rat retinal ganglion cell line 5 (RGC-5) was used as a model to study the toxicity of palmitic acid (PA), as well as underlying mechanisms. We found that PA exposure significantly decreased cell viability by enhancing apoptosis in RGC-5 cells, as measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry. PA also induced a remarkable increase in reactive oxygen species and malondialdehyde. Moreover, PA significantly decreased the level of phospho-Akt and phospho-FoxO1 in cells. Finally, shRNA knockdown and plasmid overexpression studies displayed that downregulation of Akt protein or upregulation of FoxO1 protein augmented cell death, while knockdown of FoxO1 or overexpression of Akt1 abolished PA-induced cell death. Collectively, our results indicated that PA-induced cell death is mediated through modulation of Akt/FoxO1 pathway activity.

Effect of lithium on ventricular remodelling in infarcted rats via the Akt/mTOR signalling pathways

Activation of phosphoinositide 3-kinase (PI3K)/Akt signalling is the molecular pathway driving physiological hypertrophy. As lithium, a PI3K agonist, is highly toxic at regular doses, we assessed the effect of lithium at a lower dose on ventricular hypertrophy after myocardial infarction (MI). Male Wistar rats after induction of MI were randomized to either vehicle or lithium (1 mmol/kg per day) for 4 weeks. The dose of lithium led to a mean serum level of 0.39 mM, substantially lower than the therapeutic concentrations (0.8–1.2 mM). Infarction in the vehicle was characterized by pathological hypertrophy in the remote zone; histologically, by increased cardiomyocyte sizes, interstitial fibrosis and left ventricular dilatation; functionally, by impaired cardiac contractility; and molecularly, by an increase of p-extracellular-signal-regulated kinase (ERK) levels, nuclear factor of activated T cells (NFAT) activity, GATA4 expression and foetal gene expressions. Lithium administration mitigated pathological remodelling. Furthermore, lithium caused increased phosphorylation of eukaryotic initiation factor 4E binding protein 1 (p-4E-BP1), the downstream target of mammalian target of rapamycin (mTOR). Blockade of the Akt and mTOR signalling pathway with deguelin and rapamycin resulted in markedly diminished levels of p-4E-BP1, but not ERK. The present study demonstrated that chronic lithium treatment at low doses mitigates pathological hypertrophy through an Akt/mTOR dependent pathway.

Nerve growth factor protects against palmitic acid-induced injury in retinal ganglion cells

Accumulating evidence supports an important role for nerve growth factor (NGF) in diabetic retinopathy. We hypothesized that NGF has a protective effect on rat retinal ganglion RGC-5 cells injured by palmitic acid (PA), a metabolic factor implicated in the development of diabetes and its complications. Our results show that PA exposure caused apoptosis of RGC-5 cells, while NGF protected against PA insult in a concentration-dependent manner. Additionally, NGF significantly attenuated the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) in RGC-5 cells. Pathway inhibitor tests showed that the protective effect of NGF was completely reversed by LY294002 (PI3K inhibitor), Akt VIII inhibitor, and PD98059 (ERK1/2 inhibitor). Western blot analysis revealed that NGF induced the phosphorylation of Akt/FoxO1 and ERK1/2 and reversed the PA-evoked reduction in the levels of these proteins. These results indicate that NGF protects RGC-5 cells against PA-induced injury through anti-oxidation and inhibition of apoptosis by modulation of the PI3K/Akt and ERK1/2 signaling pathways.