Neurotoxicity induced by dexamethasone in the human neuroblastoma SH-SY5Y cell line can be prevented by folic acid

Dexamethasone upregulates macrophage PIEZO1 via SGK1, suppressing inflammation and increasing ROS and apoptosis

The side effects of high-dose dexamethasone in anti-infection include increased ROS production and immune cell apoptosis. Dexamethasone effectively activates serum/glucocorticoid-regulated kinase 1 (SGK1), which upregulates various ion channels by activating store-operated calcium entry (SOCE), leading to Ca2+ oscillations. PIEZO1 plays a crucial role in macrophages' immune activity and function, but whether dexamethasone can regulate PIEZO1 by enhancing SOCE via SGK1 activation remains unclear. The effects of dexamethasone were assessed in a mouse model of sepsis, and primary BMDMs and the RAW264.7 were treated with overexpression plasmids, siRNAs, or specific activators or inhibitors to examine the relationships between SGK1, SOCE, and PIEZO1. The functional and phenotypic changes of mouse and macrophage models were detected. The results indicate that high-dose dexamethasone upregulated SGK1 by activating the macrophage glucocorticoid receptor, which enhanced SOCE and subsequently activated PIEZO1. Activation of PIEZO1 resulted in Ca2+ influx and cytoskeletal remodelling. The increase in intracellular Ca2+ mediated by PIEZO1 further increased the activation of SGK1 and ORAI1/STIM1, leading to intracellular Ca2+ peaks. In the context of inflammation, activation of PIEZO1 suppressed the activation of TLR4/NFκB p65 in macrophages. In RAW264.7 cells, PIEZO1 continuous activation inhibited the change in mitochondrial membrane potential, accelerated ROS accumulation, and induced autophagic damage and cell apoptosis in the late stage. CaMK2α was identified as a downstream mediator of TLR4 and PIEZO1, facilitating high-dose dexamethasone-induced macrophage immunosuppression and apoptosis. PIEZO1 is a new glucocorticoid target to regulate macrophage function and activity. This study provides a theoretical basis for the rational use of dexamethasone.

Effects of Combining Biofactors on Bioenergetic Parameters, Aβ Levels and Survival in Alzheimer Model Organisms

Increased amyloid beta (Aβ) levels and mitochondrial dysfunction (MD) in the human brain characterize Alzheimer disease (AD). Folic acid, magnesium and vitamin B6 are essential micro-nutrients that may provide neuroprotection. Bioenergetic parameters and amyloid precursor protein (APP) processing products were investigated in vitro in human neuroblastoma SH-SY5Y-APP695 cells, expressing neuronal APP, and in vivo, in the invertebrate Caenorhabditis elegans (CL2006 & GMC101) expressing muscular APP. Model organisms were incubated with either folic acid and magnesium-orotate (ID63) or folic acid, magnesium-orotate and vitamin B6 (ID64) in different concentrations. ID63 and ID64 reduced Aβ, soluble alpha APP (sAPPα), and lactate levels in SH-SY5Y-APP695 cells. The latter might be explained by enhanced expression of lactate dehydrogenase (LDHA). Micronutrient combinations had no effects on mitochondrial parameters in SH-SY5Y-APP695 cells. ID64 showed a significant life-prolonging effect in C. elegans CL2006. Incubation of GMC101 with ID63 significantly lowered Aβ aggregation. Both combinations significantly reduced paralysis and thus improved the phenotype in GMC101. Thus, the combinations of the tested biofactors are effective in pre-clinical models of AD by interfering with Aβ related pathways and glycolysis.

Human Embryonic Stem Cell-Derived Neural Lineages as In Vitro Models for Screening the Neuroprotective Properties of Lignosus rhinocerus (Cooke) Ryvarden

In the biomedical field, there is growing interest in using human stem cell-derived neurons as in vitro models for pharmacological and toxicological screening of bioactive compounds extracted from natural products. Lignosus rhinocerus (Tiger Milk Mushroom) is used by indigenous communities in Malaysia as a traditional medicine to treat various diseases. The sclerotium of L. rhinocerus has been reported to have medicinal properties, including various bioactivities such as neuritogenic, anti-inflammatory, and anticancer effects. This study aims to investigate the neuroprotective activities of L. rhinocerus sclerotial extracts. Human embryonic stem cell (hESC)-derived neural lineages exposed to the synthetic glucocorticoid, dexamethasone (DEX), were used as the in vitro models. Excess glucocorticoids have been shown to adversely affect fetal brain development and impair differentiation of neural progenitor cells. Screening of different L. rhinocerus sclerotial extracts and DEX on the hESC-derived neural lineages was conducted using cell viability and neurite outgrowth assays. The neuroprotective effects of L. rhinocerus sclerotial extracts against DEX were further evaluated using apoptosis assays and Western blot analysis. Hot aqueous and methanol extracts of L. rhinocerus sclerotium promoted neurite outgrowth of hESC-derived neural stem cells (NSCs) with negligible cytotoxicity. Treatment with DEX decreased viability of NSCs by inducing apoptosis. Coincubation of L. rhinocerus methanol extract with DEX attenuated the DEX-induced apoptosis and reduction in phospho-Akt (pAkt) level in NSCs. These results suggest the involvement of Akt signaling in the neuroprotection of L. rhinocerus methanol extract against DEX-induced apoptosis in NSCs. Methanol extract of L. rhinocerus sclerotium exhibited potential neuroprotective activities against DEX-induced toxicity in hESC-derived NSCs. This study thus validates the use of human stem cell-derived neural lineages as potential in vitro models for screening of natural products with neuroprotective properties.

Standardized Citrus unshiu peel extract ameliorates dexamethasone-induced neurotoxicity and depressive-like behaviors in mice

Dried Citrus unshiu peel, also known as Chinpi, have been commonly used as a traditional medicine to improve for allergy, inflammation and hepatopathy. Many previously studies have reported that citrus flavonoids show neuroprotective activities. However, the antidepressant-related effects of C. unshiu peels have not been well characterized. Here, the antidepressant-like effects of standardized C. unshiu peel extract (SCP) were evaluated in in vivo and in vitro depression models induced by dexamethasone (DEX), a synthetic glucocorticoid. Male ICR mice (9-week-old) were injected the DEX (40 mg/kg) and were orally given SCP daily (30, 100, and 300 mg/kg) for 14 consecutive days. The depressive-like behaviors were determined by use of open filed test (OFT), sucrose preference test (SPT), tail suspension test (TST), and forced swim test (FST). We show that treatment with SCP significantly alleviated DEX-induced depressive-like behaviors and reduced neurotoxicity in a concentration dependent manner in SH-SY5Y cells. Additionally, repeated DEX injection markedly decreased brain derived neurotrophic factor (BDNF) level, tropomyosin receptor kinase B (TrkB), and cyclic AMP-response element-binding protein (CREB), while SCP treatment improved these levels in the cerebral cortex and hippocampus regions. Our findings suggest that SCP exhibits significant antidepressant-like effects in the DEX-induced depressive animal model, and this activity may be mediated by preventing corticosterone-induced neurotoxicity.

Changes in behavioural parameters, oxidative stress and neurotrophins in the brain of adult offspring induced to an animal model of schizophrenia: The effects of FA deficient or FA supplemented diet during the neurodevelopmental phase

A deficiency of maternal folic acid (FA) can compromise the function and development of the brain, and may produce a susceptibility to diseases such as schizophrenia (SZ) in the later life of offspring. The aim of this study was to evaluate the effects of both FA deficient and FA supplemented diets during gestation and lactation on behavioural parameters, the markers of oxidative stress and neurotrophic factors in adult offspring which had been subjected to an animal model of SZ. Female mother rats (Dam's) were separated into experimental maternal groups, which began receiving a special diet (food) consisting of the AIN-93 diet, a control diet, or an FA deficient diet during the periods of pregnancy and lactation. Dam's receiving the control diet were further subdivided into four groups: one group received only control diet, while three groups to receive supplementation with FA at different doses (5, 10 and 50 mg/kg). Adult offspring bred from the Dam's were divided into ten groups for induction of the animal model of SZ through the administration of ketamine (Ket) (25 mg/kg). After the last administration of the drug, the animals were subjected to the behavioural tests and were then euthanized. The frontal cortex (FC) and hippocampus (Hip) were then dissected for later biochemical analysis. Our data demonstrates that Ket induced the model of SZ by altering the behavioural parameters (e.g. hyperlocomotion, social impairment, deficits in the sensory-motor profile and memory damage in the adult animals); and also caused changes in the parameters of oxidative stress (lipid hydroperoxide - LPO; 8-isoprostane - 8-ISO; 4-hydroxynonenal - 4-HNE; protein carbonyl content; superoxide dismutase - SOD and catalase - CAT) as well as in the levels of neurotrophic factors (brain-derived neurotrophic factor - BDNF and nerve growth factor - NGF) particularly within the FC of adult offspring. A deficiency in maternal FA, alone or in combination with ket, was able to induce hyperlocomotion and social impairment in the offspring with increased levels of lipid and protein damage (LPO, 8-ISO, 4-HNE, carbonylation of protein) within the FC, increased activity of antioxidant enzymes (SOD and CAT) in both of the brain structures studied, and also reduced the levels of neurotrophins (BDNF and NGF), particularly within the Hip of the adult offspring. Supplementation of FA (5, 10 and 50 mg/kg) to the Dam's was mostly able to prevent the cognitive damage which was induced by Ket in the adult animals. FA (10 and 50 mg/kg) attenuated the action of Ket in the animals in relation to the biochemical parameters, proving the possible neuroprotective effect of FA in the adulthood of offspring that were subjected to the animal model of SZ. Our study indicates that the intake of maternal FA during pregnancy and lactation plays an important role, particularly in the regulation of markers of oxidative stress and neurotrophins.

The preventive effects of edible folic acid on cardiomyocyte apoptosis and survival in early onset triple-transgenic Alzheimer's disease model mice

In recent years, neuropathological and epidemiological studies have indicated an association between Alzheimer's disease (AD) and several cardiovascular risk factors. In this study, the cardio-protective effects of folic acid (FA) in early stage AD was elucidated using a triple-transgenic (3xTg) Alzheimer's mouse model. Eleven-month-old C57BL/6 mice and 3xTg mice were assigned to five groups. During the four-month treatment period, the low-FA treatment group received FA through their diet, and the high-FA treatment groups received 3 mg/dl folate in drinking water and were also gastric-fed 1.2 mg/kg folate every day. In the C57B1/6J mice, treatment with high doses of FA (HFA) did not show any considerable effect compared to the control group or the low-dose dietary FA treatment group. However, Alzheimer's mice treated with HFA showed enhanced cardio-protection. Western blot analysis revealed that FA treatment restored SIRT1 expression, which was suppressed in 3xTg mice, through enhanced AMPK expression. FA significantly enhanced the IGF1 receptor survival mechanism in the hearts of the 3xTg mice and suppressed the expression-intrinsic and extrinsic apoptosis-associated proteins. The results suggest that FA intake may significantly alleviate cellular pathological events in the heart associated with AD.

Effect of folic acid on oxidative stress and behavioral changes in the animal model of schizophrenia induced by ketamine

Recent studies have shown benefits for the supplementation of folic acid in schizophrenic patients. The aim of this study was to evaluate the effects of folic acid addition on adult rats, over a period of 7 or 14 days. It also sets out to verify any potential protective action using an animal model of schizophrenia induced by ketamine, in behavioral and biochemical parameters. This study used two protocols (acute and chronic) for the administration of ketamine at a dose of 25 mg/kg (i.p.). The folic acid was given by oral route in doses of 5, 10 and 50 mg/kg, once daily, for 7 and/or 14 days in order to compare the protective effects of folic acid. Thirty minutes after the last administration of ketamine, the locomotor and social interaction activities were evaluated, and immediately the brain structure were removed for biochemical analysis. In this study, ketamine was administered in a single dose or in doses over the course of 7 days increasing the animal's locomotion. This study showed that the administration of folic acid over 7 days was unable to prevent hyper locomotion. In contrast, folic acid (10 and 50 mg/kg) administrated over a period of 14 days, was able to partially prevent the hyper locomotion. Our data indicates that both acute and chronic administrations of ketamine increased the time to first contact between the animals, while the increased latency for social contact was completely prevented by folic acid (5, 10 and 50 mg/kg). Chronic and acute administrations of ketamine also increased lipid peroxidation and protein carbonylation in brain. Folic acid (10 and 50 mg/kg) supplements showed protective effects on the oxidative damage found in the different brain structures evaluated. All together, the results indicate that nutritional supplementation with folic acid provides promising results in an animal model of schizophrenia induced by ketamine.

Clobetasol and Halcinonide Act as Smoothened Agonists to Promote Myelin Gene Expression and RxRγ Receptor Activation

One of the causes of permanent disability in chronic multiple sclerosis patients is the inability of oligodendrocyte progenitor cells (OPCs) to terminate their maturation program at lesions. To identify key regulators of myelin gene expression acting at the last stages of OPC maturation we developed a drug repositioning strategy based on the mouse immortalized oligodendrocyte (OL) cell line Oli-neu brought to the premyelination stage by stably expressing a key factor regulating the last stages of OL maturation. The Prestwick Chemical Library^® of 1,200 FDA-approved compound(s) was repositioned at three dosages based on the induction of Myelin Basic Protein (MBP) expression. Drug hits were further validated using dosage-dependent reproducibility tests and biochemical assays. The glucocorticoid class of compounds was the most highly represented and we found that they can be divided in three groups according to their efficacy on MBP up-regulation. Since target identification is crucial before bringing compounds to the clinic, we searched for common targets of the primary screen hits based on their known chemical-target interactomes, and the pathways predicted by top ranking compounds were validated using specific inhibitors. Two of the top ranking compounds, Halcinonide and Clobetasol, act as Smoothened (Smo) agonists to up-regulate myelin gene expression in the Oli-neuM cell line. Further, RxRγ activation is required for MBP expression upon Halcinonide and Clobetasol treatment. These data indicate Clobetasol and Halcinonide as potential promyelinating drugs and also provide a mechanistic understanding of their mode of action in the pathway leading to myelination in OPCs. Furthermore, our classification of glucocorticoids with respect to MBP expression provides important novel insights into their effects in the CNS and a rational criteria for their choice in combinatorial therapies in de-myelinating diseases.

Additives to local anesthetics for peripheral nerve blocks or local anesthesia: a review of the literature

SUMMARY 

A multitude of studies have focused on individual additives to local anesthetics and their effect on quality, onset, duration, spread and selectivity, as well as the potential toxic effects of their use. This review aims to give a broad overview of the current evidence in this developing field, based on beneficial and adverse effects of these drugs. We discuss the limitations of the available data and hope to convey implications and future perspectives for clinicians and researchers alike.

Pterostilbene mediates neuroprotection against oxidative toxicity via oestrogen receptor α signalling pathways

Objectives

Accumulating evidence indicated protective role of phytoestrogens against neuronal damage induced by various insults, such as amyloid beta, oxygen deprivation and mitochondrial toxins. Hydrogen peroxide (H2O2) influences the mitochondrial membrane potential, which eventually results in cell apoptosis. In this study, we investigated the effects and possible mechanisms of a phytoestrogen, pterostilbene (PTER), in cell apoptosis induced by H2O2 in human neuronal SH-SY5Y cells. We also analysed the involvement of oestrogen receptors, oestrogen receptor-α and -β (ER-α and ER-β) in the protective role of PTER.

Methods

The effects of PTER on H2O2-stimulated cell were examined using MTT and FACS analysis. The signal pathways and estrogen receptors involved in PTER's effects were investigated using MTT and Western blot analysis.

Key findings

The results showed that H2O2 treatment significantly reduced cell viability in SY5Y cells, which was protected by PTER treatment. We also found that H2O2 inhibited the PI3K/AKT and MAPK/ERK signalling pathways, whereas PTER treatment restored these signalling pathways. We also found that the PTER effect could be largely blocked by an ER-α antagonist, 3-Bis(4-hydroxyphenyl)-4-methyl-5-[4-(2-piperidinylethoxy)phenol]-1H-pyrazole dihydrochloride (MPP), but not by an ER-β antagonist, 4-[2-Phenyl-5,7-bis(trifluoromethyl)pyrazolo[1,5-a] pyrimidin-3-yl]phenol (PHTPP), suggesting that ER-α is a major player in the neuroprotective activity of PTER.

Conclusion

Our study thus demonstrates that PTER is an effective neuroprotective agent presumably through ER-α-mediated signalling pathways.

Venlafaxine protects methylglyoxal-induced apoptosis in the cultured human brain microvascular endothelial cells

It was reported that venlafaxine protects microvascular endothelial cells injury in several models. But the mechanisms of venlafaxine protects cell injury still poor understanding. Here, we shows that in the cultured human brain microvascular endothelial cells (HBMEC), we found that venlafaxine protects methylglyoxal (MGO)-induced cell injury, and the venlafaxine significant reduction in the level of reactive oxygen species, down-regulated expression of pro-apoptotic activated caspase-3 and Bax, increased BDNF release and expression of anti-apoptotic Bcl-2 in the cultured HBMEC. Furthermore, we found that venlafaxine inhibits MGO-induced phosphorylation of JNK. Moreover, venlafaxine increased AKT phosphorylation and the protective effects of venlafaxine was inhibited by PI3K/AKT inhibitor. These findings suggest that venlafaxine protects MGO-induced HBMEC injury through PI3K/AKT and JNK pathway as the potential underlying mechanisms of HBMEC injury in diabetes.

The role of Akt/FoxO3a in the protective effect of venlafaxine against corticosterone-induced cell death in PC12 cells

RATIONALE

Antidepressants could exert neuroprotective effects against various insults and the antidepressant-like effect may result from its neuroprotective effects. The phosphatidylinositol-3-kinase/protein kinase B/Forkhead box O3 (PI3K/Akt/FoxO3a) pathway is a key signaling pathway in mediating cell survival. However, no information is available regarding the interaction of FoxO3a and antidepressants.

OBJECTIVES

PC12 cells treated with corticosterone were used as a model to study the protective effect of venlafaxine and underlying mechanisms.

METHODS

Methyl thiazolyl tetrazolium (MTT) assay, Hoechst staining, and the observation of FoxO3a subcellular location were used to study the protective effect of venlafaxine against cell damage caused by corticosterone. Pretreatments with various pathway inhibitors were used to investigate the possible pathways involved in the protection of venlafaxine. The phosphorylation of Akt and FoxO3a was analyzed by Western blot.

RESULTS

Corticosterone decreased the phosphorylation of Akt and FoxO3a and led to the nuclear localization of FoxO3a and the apoptosis of PC12 cells. Venlafaxine concentration-dependently protected PC12 cells against corticosterone. The protective effect of venlafaxine was reversed by LY294002 and wortmannin, two PI3K inhibitors, and Akt inhibitor VIII, whereas mitogen-activated protein kinase kinase (MAPK kinase) inhibitor PD98059 and the p38 MAPK inhibitor PD160316 had no effect. Western blot analyses showed that venlafaxine induced the phosphorylation of Akt and FoxO3a by the PI3K/Akt pathway and reversed the reduction of the phosphorylated Akt and FoxO3a, and the nuclear translocation of Foxo3a induced by corticosterone.

CONCLUSIONS

Venlafaxine protects PC12 cells against corticosterone-induced cell death by modulating the activity of the PI3K/Akt/FoxO3a pathway.

Involvement of PI3K, GSK-3β and PPARγ in the antidepressant-like effect of folic acid in the forced swimming test in mice

Preclinical and clinical studies indicate that deficiency in folic acid plays a role in the pathophysiology of depression. Considering that alterations in the signaling pathways that regulate neuroplasticity and cellular survival are implicated in depressive disorders, the present study investigated the involvement of the phosphoinositide 3-kinase (PI3K), glycogen synthase kinase-3 (GSK-3β), and peroxisome proliferator-activated receptor-γ (PPARγ) in the antidepressant-like effect of folic acid in the forced swimming test (FST). The intracerebroventricular (i.c.v.) pre-treatment of mice with LY294002 (10 nmol/site, a PI3K inhibitor) or GW-9662 (1 µg/site, a PPARγ antagonist) prevented the antidepressant-like effect of folic acid (50 mg/kg, p.o.) in the FST. In addition, the administration of subeffective doses of the selective GSK-3β inhibitor, AR-A014418 (3 mg/kg, i.p.), a non-selective GSK-3β inhibitor, lithium chloride (10 mg/kg, p.o) or a PPARγ agonist, rosiglitazone (1 µg/site, i.c.v.) in combination with a subeffective dose of folic acid (10 mg/kg, p.o.) significantly reduced the immobility time in the FST as compared with either drug alone, without altering the locomotor activity. These results indicate that the antidepressant-like effect of folic acid in the FST might be dependent on inhibition of GSK-3β and activation of PPARγ, reinforcing the notion that these are important targets for antidepressant activity.

Dexamethasone enhances oxidative stress-induced cell death in murine neural stem cells

Glucocorticoids (GCs) are essential for normal brain development; however, there is consistent evidence that prenatal exposure of the fetal brain to excess GCs permanently modifies the phenotype of neuronal cells. In this paper, the murine-derived multipotent stem cell line C17.2 was used, as an in vitro model, to investigate the impact of GCs on neural stem cell survival. Our results indicate that dexamethasone (Dex) increases the sensitivity of murine neural stem cells (NSCs) to 2,3-methoxy-1,4-naphthoquinone-induced apoptosis, and this effect could be blocked by the glucocorticoid-receptor (GR) antagonist mifepristone, strongly suggesting the involvement of the GR. Furthermore, our results show that Dex decreases cell number and induces a G1-arrest. We hypothesized that the mitochondria are the main target of Dex. Interestingly, after treatment with Dex, 72% of the investigated genes involved in the mitochondrial respiratory chain are down-regulated, as well as 29% of the genes encoding for antioxidant enzymes. In conclusion, using the C17.2 cell line as a model to study developmental neurotoxicity in vitro, we have shown that GCs can increase cellular sensitivity to oxidative stress and alter the phenotype of NCSs.