4-O-methylhonokiol attenuated β-amyloid-induced memory impairment through reduction of oxidative damages via inactivation of p38 MAP kinase

Oxidative stress induced neuronal cell death by accumulation of β-amyloid (Aβ) is a critical pathological mechanism of Alzheimer's disease (AD). Intracerebroventrical infusion of Aβ_1-42 (300 pmol/day per mouse) for 14 days induced neuronal cell death and memory impairment, but pre-treatment of 4-O-methylhonokiol (4-O-MH), a novel compound extracted from Magnolia officinalis for 3 weeks (0.2, 0.5 and 1.0 mg/kg) prior to the infusion of Aβ_1-42 and during the infusion dose dependently improved Aβ_1-42-induced memory impairment and prevented neuronal cell death. Additionally, 4-O-MH reduced Aβ_1-42 infusion-induced oxidative damages of protein and lipid but reduced glutathione levels in the cortex and hippocampus. Aβ_1-42 infusion-induced activation of astrocytes and p38 mitogenic activated protein (MAP) kinase was also prevented by 4-O-MH in mice brains. In further study using culture cortical neurons, p38 MAP kinase inhibitor abolished the inhibitory effect of 4-O-MH (10 μM) on the Aβ_1-42 (5 μM)-induced reactive oxidative species generation and neuronal cell death. These results suggest that 4-O-MH might prevent the development and progression of AD through the reduction of oxidative stress and neuronal cell death via inactivation of p38 MAP kinase pathway.     

Protein phosphatase 5 protects neurons against amyloid-β toxicity

Amyloid-β (Aβ) is thought to promote neuronal cell loss in Alzheimer's disease, in part through the generation of reactive oxygen species (ROS) and subsequent activation of mitogen-activated protein kinase (MAPK) pathways. Protein phosphatase 5 (PP5) is a ubiquitously expressed serine/threonine phosphatase which has been implicated in several cell stress response pathways and shown to inactivate MAPK pathways through key dephosphorylation events. Therefore, we examined whether PP5 protects dissociated embryonic rat cortical neurons in vitro from cell death evoked by Aβ. As predicted, neurons in which PP5 expression was decreased by small-interfering RNA treatment were more susceptible to Aβ toxicity. In contrast, over-expression of PP5, but not the inactive mutant, PP5(H304Q), prevented MAPK phosphorylation and neurotoxicity induced by Aβ. PP5 also prevented cell death caused by direct treatment with H₂O₂, but did not prevent Aβ-induced production of ROS. Thus, the neuroprotective effect of PP5 requires its phosphatase activity and lies downstream of Aβ-induced generation of ROS. In summary, our data indicate that PP5 plays a pivotal neuroprotective role against cell death induced by Aβ and oxidative stress. Consequently, PP5 might be an effective therapeutic target in Alzheimer's disease and other neurodegenerative disorders in which oxidative stress is implicated.     

Protection of Flupirtine on β-Amyloid-Induced Apoptosis in Neuronal Cells In Vitro: Prevention of Amyloid-Induced Glutathione Depletion

Abstract: Effective drugs are not available to protect against β-amyloid peptide (Aβ)-induced neurotoxicity. Cortical neurons from rat embryos were treated with the toxic fragment Aβ25-35 at 1 µ M in the presence or absence of flupirtine, a triaminopyridine, successfully applied clinically as a nonopiate analgesic drug. Five days later 1 µ M Aβ25-35 caused reduction of cell viability to 31.1%. Preincubation of cells with flupirtine (1 or 5 µg/ml) resulted in a significant increase of the percentage of viable cells (74.6 and 65.4%, respectively). During incubation with Aβ25-35 the neurons undergo apoptosis as determined by appearance of the characteristic stepladder-like DNA fragmentation pattern and by the TUNEL technique. Aβ25-35-induced DNA fragmentation could be abolished by preincubation of the cells with 1 µg/ml flupirtine. Incubation with Aβ25-35 reduces the intraneuronal level of GSH from 21.4 to 7.4 nmol/10⁶ cells. This depletion could be partially prevented by preincubation of the cells with flupirtine. Thus, flupirtine may be adequate for the treatment of the neuronal loss in Alzheimer's disease (where Aβ accumulates in senile plaques) and probably other neurological diseases such as amyotrophic lateral sclerosis.     

Neurodegeneration in an Aβ-induced model of Alzheimer's disease: the role of Cdk5

Cdk5 dysregulation is a major event in the neurodegenerative process of Alzheimer's disease (AD). In vitro studies using differentiated neurons exposed to Aβ exhibit Cdk5-mediated tau hyperphosphorylation, cell cycle re-entry and neuronal loss. In this study we aimed to determine the role of Cdk5 in neuronal injury occurring in an AD mouse model obtained through the intracerebroventricular (icv) injection of the Aβ_1–40 synthetic peptide. In mice icv-injected with Aβ, Cdk5 activator p35 is cleaved by calpains, leading to p25 formation and Cdk5 overactivation. Subsequently, there was an increase in tau hyperphosphorylation, as well as decreased levels of synaptic markers. Cell cycle reactivation and a significant neuronal loss were also observed. These neurotoxic events in Aβ-injected mice were prevented by blocking calpain activation with MDL28170 , which was administered intraperitoneally (ip). As MDL prevents p35 cleavage and subsequent Cdk5 overactivation, it is likely that this kinase is involved in tau hyperphosphorylation, cell cycle re-entry, synaptic loss and neuronal death triggered by Aβ. Altogether, these data demonstrate that Cdk5 plays a pivotal role in tau phosphorylation, cell cycle induction, synaptotoxicity, and apoptotic death in postmitotic neurons exposed to Aβ peptides in vivo , acting as a link between diverse neurotoxic pathways of AD.     

Estrogens Attenuate and Corticosterone Exacerbates Excitotoxicity, Oxidative Injury, and Amyloid β-Peptide Toxicity in Hippocampal Neurons

Abstract: Steroid hormones, particularly estrogens and glucocorticoids, may play roles in the pathogenesis of neurodegenerative disorders, but their mechanisms of action are not known. We report that estrogens protect cultured hippocampal neurons against glutamate toxicity, glucose deprivation, FeSO₄ toxicity, and amyloid β-peptide (Aβ) toxicity. The toxicity of each insult was significantly attenuated in cultures pretreated for 2 h with 100 n M -10 µ M 17β-estradiol, estriol, or progesterone. In contrast, corticosterone exacerbated neuronal injury induced by glutamate, FeSO₄, and Aβ. Several other steroids, including testosterone, aldosterone, and vitamin D, had no effect on neuronal vulnerability to the different insults. The protective actions of estrogens and progesterone were not blocked by actinomycin D or cycloheximide. Lipid peroxidation induced by FeSO₄ and Aβ was significantly attenuated in neurons and isolated membranes pretreated with estrogens and progesterone, suggesting that these steroids possess antioxidant activities. Estrogens and progesterone also attenuated Aβ- and glutamate-induced elevation of intracellular free Ca²⁺ concentrations. We conclude that estrogens, progesterone, and corticosterone can directly affect neuronal vulnerability to excitotoxic, metabolic, and oxidative insults, suggesting roles for these steroids in several different neurodegenerative disorders.     

Sesaminol Glucosides Protect β-Amyloid Induced Apoptotic Cell Death by Regulating Redox System in SK-N-SH Cells

We have investigated the neuroprotective effect of sesaminol glucosides (SG) in SK-N-SH cells. SG prevented apoptotic cell death induced by Aβ_25–35. In parallel, SK-N-SH cells exposed to Aβ_25–35 underwent oxidative stress as shown by the elevated level of intracellular ROS, lipid peroxidation, and 8-hydroxy-2′-deoxyguanosine (8-OHdG) formation, which were effectively suppressed by SG treatment. Furthermore, SG reversed the activities of catalase and glutathione peroxidase, and restored intracellular GSH levels in Aβ_25–35 challenged SK-N-SH cells. In addition, SG inhibited not only Aβ_25–35-induced apoptotic features including cleavage of poly(ADP-ribose) polymerase, activation of caspase-3, and activation of caspase-9, but also elevated Bax/Bcl-2 ratio in SK-N-SH cells treated with Aβ_25–35. It was also observed that Aβ_25–35 stimulated the phosphorylation of mitogen-activated protein kinases (MAPKs), including extracellular protein regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 MAP kinase. SG inhibited phosphorylation of the JNK, ERK and p38 MAP kinase. These results suggest that SG has a protective effect against Aβ_25–35-induced neuronal apoptosis, possibly through scavenging oxidative stress and regulating MAPKs signaling pathways.     

p38 MAP kinase mediates bax translocation in nitric oxide-induced apoptosis in neurons

Nitric oxide is a chemical messenger implicated in neuronal damage associated with ischemia, neurodegenerative disease, and excitotoxicity. Excitotoxic injury leads to increased NO formation, as well as stimulation of the p38 mitogen-activated protein (MAP) kinase in neurons. In the present study, we determined if NO-induced cell death in neurons was dependent on p38 MAP kinase activity. Sodium nitroprusside (SNP), an NO donor, elevated caspase activity and induced death in human SH-SY5Y neuroblastoma cells and primary cultures of cortical neurons. Concomitant treatment with SB203580, a p38 MAP kinase inhibitor, diminished caspase induction and protected SH-SY5Y cells and primary cultures of cortical neurons from NO-induced cell death, whereas the caspase inhibitor zVAD-fmk did not provide significant protection. A role for p38 MAP kinase was further substantiated by the observation that SB203580 blocked translocation of the cell death activator, Bax, from the cytosol to the mitochondria after treatment with SNP. Moreover, expressing a constitutively active form of MKK3, a direct activator of p38 MAP kinase promoted Bax translocation and cell death in the absence of SNP. Bax-deficient cortical neurons were resistant to SNP, further demonstrating the necessity of Bax in this mode of cell death. These results demonstrate that p38 MAP kinase activity plays a critical role in NO-mediated cell death in neurons by stimulating Bax translocation to the mitochondria, thereby activating the cell death pathway.     

The Lipid Peroxidation Product, 4-Hydroxy-2-trans-Nonenal, Alters the Conformation of Cortical Synaptosomal Membrane Proteins

Abstract: Alzheimer's disease (AD) is widely held to be a disorder associated with oxidative stress due, in part, to the membrane action of amyloid β-peptide (Aβ). Aβ-associated free radicals cause lipid peroxidation, a major product of which is 4-hydroxy-2- trans -nonenal (HNE). We determined whether HNE would alter the conformation of synaptosomal membrane proteins, which might be related to the known neurotoxicity of Aβ and HNE. Electron paramagnetic resonance spectroscopy, using a protein-specific spin label, MAL-6(2,2,6,6-tetramethyl-4-maleimidopiperidin-1-oxyl), was used to probe conformational changes in gerbil cortical synaptosomal membrane proteins, and a lipid-specific stearic acid label, 5-nitroxide stearate, was used to probe for HNE-induced alterations in the fluidity of the bilayer domain of these membranes. Synaptosomal membranes, incubated with low concentrations of HNE, exhibited changes in protein conformation and bilayer order and motion (fluidity). The changes in protein conformation were found to be concentration- and time-dependent. Significant protein conformational changes were observed at physiologically relevant concentrations of 1–10 µ M HNE, reminiscent of similar changes in synaptosomal membrane proteins from senile plaque- and Aβ-rich AD hippocampal and inferior parietal brain regions. HNE-induced modifications in the physical state of gerbil synaptosomal membrane proteins were prevented completely by using excess glutathione ethyl ester, known to protect neurons from HNE-caused neurotoxicity. Membrane fluidity was found to increase at higher concentrations of HNE (50 µ M ). The results obtained are discussed with relevance to the hypothesis of Aβ-induced free radical-mediated lipid peroxidation, leading to subsequent HNE-induced alterations in the structure and function of key membrane proteins with consequent neurotoxicity in AD brain.     

p38α MAP Kinase Mediates Hypoxia-Induced Motor Neuron Cell Death: A Potential Target of Minocycline’s Neuroprotective Action

Hypoxia-ischemia (HI) may play a significant role in motor neuron death associated with the pathology of spinal cord injury and, perhaps, amyotrophic lateral sclerosis. The present study employs an in vitro model of HI to investigate the role of a stress kinase pathway, i.e., p38 MAP kinase, in cell death signaling in a motor neuron cell line, i.e., NSC34, subjected to oxygen-glucose deprivation (OGD). Although the neurons were essentially tolerant to either hypoxia (0.2% O₂) or low glucose (1 mM) alone, more than 60% of them died in response to combined low oxygen and low-glucose exposure. Minocycline, a semi-synthetic tetracycline known for its neuroprotective effects in models of neurodegeneration, afforded substantial (∼50%) protection against hypoxic cell death, assessed by lactate dehydrogenase release and flow cytometry, while suppressing OGD-induced p38 MAP kinase activation. An inhibitor of p38 kinase, SB203580, as well as siRNA-mediated down-regulation of p38 kinase elicited an almost complete blockade of OGD-induced cell death. The use of p38 isoform-specific siRNAs further revealed preferential involvement of the α over the β isoform of p38 MAP kinase in hypoxic neuronal cell death in our model.     

Cytotoxic Effect of β-Amyloid on a Human Differentiated Neuron Is Not Mediated by Cytoplasmic Ca2+ Accumulation

Abstract: The effects of synthetic β-amyloid (Aβ1–42) on cell viability and cellular Ca²⁺ homeostasis have been studied in the human neuron-like NT2N cell, which differentiates from a teratocarcinoma cell line, NTera2/C1.D1, by retinoic acid treatment. NT2N viability was measured using morphological criteria and fluorescent live/dead staining and quantified using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide metabolism. Aβ1–42 dose-dependently caused NT2N cell death when it was present in the cell culture for 14 days but had no effect on viability when it was present for 4 days. The lowest effective concentration was 4 µ M , and the strongest effect was produced by 40 µ M . Control NT2N cells produced spontaneous cytosolic Ca²⁺ oscillations under basal conditions. These oscillations were inhibited dose-dependently (0.4–40 µ M ) by Aβ1–42 that was present in the cell culture for 1 or 4 days. Ca²⁺ wave frequency was decreased from 0.21 ± 0.02 to 0.05 ± 0.02/min, amplitude from 88 ± 8 to 13 ± 4 n M , and average Ca²⁺ level from 130 ± 8 to 58 ± 3 n M . The Ca²⁺ responses to 30 m M K⁺ and 100 µ M glutamate were not different between control and Aβ-treated cells. Thus, the results do not support the hypothesis that cytosolic early Ca²⁺ accumulation mediates Aβ-induced NT2N cell death.     

Neuroprotective effects of donepezil through inhibition of GSK-3 activity in amyloid-β-induced neuronal cell death

Acetylcholinesterase inhibitors (AChE-inhibitors) are used for the treatment of Alzheimer's disease. Recently, the AChE-inhibitor donepezil was found to have neuroprotective effects. However, the protective mechanisms of donepezil have not yet been clearly identified. We investigated the neuroprotective effects of donepezil and other AChE-inhibitors against amyloid-β1–42 (Aβ42)-induced neurotoxicity in rat cortical neurons. To evaluate the neuroprotective effects of AChE-inhibitors, primary cultured cortical neurons were pre-treated with several concentrations of AChE-inhibitors for 24 h and then treated with 20 μM Aβ42 for 6 h. In addition to donepezil, other AChE-inhibitors (galantamine and huperizine A) also showed increased neuronal cell viability against Aβ42 toxicity in a concentration-dependent manner. However, we demonstrated that donepezil has a more potent effect in inhibiting glycogen synthase kinase-3 (GSK-3) activity compared with other AChE-inhibitors. The neuroprotective effects of donepezil were blocked by LY294002 (10 μM), a phosphoinositide 3 kinase inhibitor, but only partially by mecamylamine (10 μM), a blocker of nicotinic acetylcholine receptors. Additionally, donepezil's neuroprotective mechanism was related to the enhanced phosphorylation of Akt and GSK-3β and reduced phosphorylation of tau and glycogen synthase. These results suggest that donepezil prevents Aβ42-induced neurotoxicity through the activation of phosphoinositide 3 kinase/Akt and inhibition of GSK-3, as well as through the activation of nicotinic acetylcholine receptors.     

Oxidative stress-induced apoptosis in dividing fibroblasts involves activation of p38 MAP kinase and over-expression of Bax: resistance of quiescent cells to oxidative stress

Oxidative stress has been postulated to be involved in aging and age-related degenerative diseases. Cell death as a result of oxidative stress plays an important role in the age related diseases. Using human diploid fibroblasts (HDF) as model to study the mechanism of cell death induced by oxidative stress, a condition was standardized to induce apoptosis in the early passage sub-confluent HDFs by a brief exposure of cells to 250 M hydrogen peroxide. It was observed that p38 MAP kinase (MAPK) was activated soon after the treatment followed by over-expression of Bax protein in cells undergoing apoptosis. An interesting finding of the present study is that the confluent, quiescent HDFs were resistant to cell death under identical condition of oxidative stress. The contact-inhibited quiescent HDFs exhibited increased glutathione level following H₂O₂-treatment, did not activate p38 MAP kinase, or over-express Bax, and were resistant to cell death. These findings indicated that there was a correlation between the cell cycle and sensitivity to oxidative stress. This is the first report to our knowledge that describes a relationship between the quiescence state and anti-oxidative defense. Furthermore, our results also suggest that the p38MAPK activation-Bax expression pathway might be involved in apoptosis induced by oxidative stress.     

Pro-apoptotic signaling in neuronal cells following iron and amyloid beta peptide neurotoxicity

In a previous report, we characterized several oxidative stress parameters during the course of amyloid beta (Abeta) peptide/Fe2+-induced apoptotic death in neuronal cells. In extending these findings, we now report a marked decrease in protein kinase C (PKC) isoforms, reduced Akt serine/threonine kinase activity, Bcl 2-associated death promoter (BAD) phosphorylation and enhanced p38 mitogen-activated protein kinase (MAPK) and caspase-9 and -3 activation, 12 h after addition of both 5 micro m Abeta and 5 micro m Fe2+. These activities reminiscent for a pro-apoptotic cellular course were blocked in the presence of the iron chelator deferroxamine. Abeta alone, increased PKC isoform levels between three- and four-fold after 12 h, enhanced Akt activity approximately eight-fold and Ser136 BAD phosphorylation two-fold, suggesting that by itself is not toxic. Fe2+ alone transiently enhanced p38 MAPK and caspase-9 and -3 enzymes indicative for cell damage, but was not sufficient to cause cell death as previously indicated. GF, a PKC inhibitor or wortmannin, a blocker of the Akt pathway enhanced Abeta/Fe2+-induced toxicity, while SB, a p38 MAPK inhibitor, prevented cell damage and apoptosis. These findings further support the hypothesis that metal ion chelation and inhibitors of pro-apoptotic kinase cascades may be beneficial for Alzheimer's disease therapy.     

Pituitary adenylate cyclase-activating polypeptide (PACAP) prevents hippocampal neurons from apoptosis by inhibiting JNK/SAPK and p38 signal transduction pathways

We have demonstrated that ischemic neuronal death (apoptosis) of rat CA1 region of the hippocampus was prevented by infusing pituitary adenylate cyclase-activating polypeptide (PACAP) either intracerebroventricularly or intravenously. We have also demonstrated that the activity of mitogen-activated protein (MAP) kinase family members, including ERK (extracellular signal-regulated kinase), Jun N-terminal kinase (JNK)/stress-activated protein kinase (SAPK) and p38, was increased in the hippocampus within 1-6 h after brain ischemia. The molecular mechanisms underlying the PACAP anti-apoptotic effect were demonstrated in this study. Ischemic stress had a strong influence on MAP kinase family, especially on JNK/SAPK and p38. PACAP inhibited the activation of JNK/SAPK and p38 after ischemic stress, while ERK is not suppressed. These findings suggest that PACAP inhibits the JNK/SAPK and p38 signaling pathways, thereby protecting neurons against apoptosis.     

MKK3 and -6-dependent activation of p38alpha MAP kinase is required for cytoskeletal changes in pulmonary microvascular endothelial cells induced by ICAM-1 ligation

Previous studies demonstrated that neutrophil adherence induces ICAM-1-dependent cytoskeletal changes in TNF-alpha-treated pulmonary microvascular endothelial cells that are prevented by a pharmacological inhibitor of p38 MAP kinase. This study determined whether neutrophil adherence induces activation of p38 MAP kinase in endothelial cells, the subcellular localization of phosphorylated p38, which MAP kinase kinases lead to p38 activation, which p38 isoform is activated, and what the downstream targets may be. Confocal microscopy showed that neutrophil adhesion for 2 or 6 min induced an increase in phosphorylated p38 in endothelial cells that was punctate and concentrated in the central region of the endothelial cells. Studies using small interfering RNA (siRNA) to inhibit the protein expression of MAP kinase kinase 3 and 6, either singly or in combination, showed that both MAP kinase kinases were required for p38 phosphorylation. Studies using an antisense oligonucleotide to p38alpha demonstrated that inhibition of the protein expression of p38alpha 1) inhibited activation of p38 MAP kinase without affecting the protein expression of p38beta; 2) prevented phosphorylation of heat shock protein 27, an actin binding protein that may induce actin polymerization upon phosphorylation; 3) attenuated cytoskeletal changes; and 4) attenuated neutrophil migration to the EC borders. Thus MAP kinase kinase3- and 6-dependent activation of the alpha-isoform of p38 MAP kinase is required for the cytoskeletal changes induced by neutrophil adherence and influences subsequent neutrophil migration toward endothelial cell junctions.     

A Role for 4-Hydroxynonenal, an Aldehydic Product of Lipid Peroxidation, in Disruption of Ion Homeostasis and Neuronal Death Induced by Amyloid β-Peptide

Abstract: Peroxidation of membrane lipids results in release of the aldehyde 4-hydroxynonenal (HNE), which is known to conjugate to specific amino acids of proteins and may alter their function. Because accumulating data indicate that free radicals mediate injury and death of neurons in Alzheimer's disease (AD) and because amyloid β-peptide (Aβ) can promote free radical production, we tested the hypothesis that HNE mediates Aβ25-35-induced disruption of neuronal ion homeostasis and cell death. Aβ induced large increases in levels of free and protein-bound HNE in cultured hippocampal cells. HNE was neurotoxic in a time- and concentration-dependent manner, and this toxicity was specific in that other aldehydic lipid peroxidation products were not neurotoxic. HNE impaired Na⁺,K⁺-ATPase activity and induced an increase of neuronal intracellular free Ca²⁺ concentration. HNE increased neuronal vulnerability to glutamate toxicity, and HNE toxicity was partially attenuated by NMDA receptor antagonists, suggesting an excitotoxic component to HNE neurotoxicity. Glutathione, which was previously shown to play a key role in HNE metabolism in nonneuronal cells, attenuated the neurotoxicities of both Aβ and HNE. The antioxidant propyl gallate protected neurons against Aβ toxicity but was less effective in protecting against HNE toxicity. Collectively, the data suggest that HNE mediates Aβ-induced oxidative damage to neuronal membrane proteins, which, in turn, leads to disruption of ion homeostasis and cell degeneration.     

Proteins with pathogenic polyglutamine expansion inhibit fast axonal transport

The mechanisms underlying neuronal degeneration in Alzheimer's disease (AD) are very controversial and none more so than whether apoptosis plays a role. Although neurons in AD face a wide assortment of apoptogenic stimuli, the temporal dichotomy between the acuteness of apoptosis vs. the chronicity of AD suggests that apoptosis should be extremely rare in AD. In this regard, survival factor(s) must be involved. In this study, we investigated Bcl-w, a pro-survival member of the Bcl-2 family. Although expressed at low levels in brains of control cases, Bcl-w is significantly up-regulated in AD as shown by both immunocytochemistry and immunoblot analysis. Astonishingly, increased Bcl-w was found to be associated with neurofibrillary pathologies in AD, which was further demonstrated by an EM study. Since neuronal death in AD is thought to be triggered by increased production of amyloid-β (Aβ), it was interesting to find that exposure of human M17 neuroblastoma cells to Aβ1–42 (1 n m −10 μ m ) dramatically up-regulates Bcl-w protein levels. Such increases may be a protective response that attenuates apoptotic processes. Consistent with this, transfected M17 cells overexpressing Bcl-w were protected from both STS-induced and Aβ-induced apoptosis compared to vector-transfected controls. Notably, both tau phosphorylation and p38 is inhibited in Bcl-w transfected cells which may contribute to the neuroprotective role of Bcl-w. Taken together, these set of in vitro and in vivo results suggest that Bcl-w plays an important protective role in neurons in the AD brain.     

F-spondin plays a critical role in murine neuroblastoma survival by maintaining IL-6 expression

F-spondin is associated with the regulation of axonal growth and the development of the nervous system. Its mechanism of action, however, is not clearly understood. In this study, we found that murine neuroblastoma Neuro-2a cells expressed a significant level of IL-6, but only trace amounts of IL-12, tumor necrosis factor α and nitric oxide. Knock-down of F-spondin mRNA in murine neuroblastoma NB41A3 and Neuro-2a cells using small interfering RNAs led to decreased IL-6 levels along with lower resistance to serum starvation and cytotoxic amyloid β_1–42 (Aβ_1–42) peptide. Restoring decline of F-spondin or IL-6 induced by F-spondin knock-down through adding exogenous F-spondin, IL-6 or over-expressing F-spondin reversed the cell death induced by Aβ_1–42 peptide or serum starvation. The decrease of IL-6 level was positively correlated with decrease of NF-κB and inhibition of p38 mitogen-activated protein kinase (MAPK). Over-expressing MEKK, a kinase activator of the p38 MAPK pathway, increased IL-6 production, restored the decrease of p38 induced by F-spondin knock-down, and rescued the cells from death caused by Aβ_1–42 peptide. Taken together, these results suggest that F-spondin may play a critical role in murine neuroblastoma survival under adverse conditions by maintaining IL-6 level via a MEKK/p38 MAPK/NF-κB-dependent pathway.