Evidence for involvement of ERK, PI3K, and RSK in induction of Bcl-2 by valproate

GLUL gene knockdown and restricted glucose level show synergistic inhibitory effect on the luminal subtype breast cancer MCF7 cells' proliferation and metastasis

The glutamine synthetase path is one of the most important metabolic pathways in luminal breast cancer cells, which plays a critical role in supplying glutamine as an intermediate in the biosynthesis of amino acids and nucleotides. On the other hand, glycolysis and its dominant substrate, glucose, are the most critical players in cancer metabolism. Accordingly, targeting these two critical paths might be more efficient in luminal-type breast cancer treatment. MCF7 cells were cultivated in media containing 4.5, 2, and 1 g/L glucose to study its effects on GLUL (Glutamate Ammonia Ligase) expression. Followingly, high and low glucose cell cultures were transfected with 220 pM of siGLUL and incubated for 48 h at 37 ºC. The cell cycle progression and apoptosis were monitored and assessed by flow cytometry. Expression of GLUL, known as glutamine synthetase, was evaluated in mRNA and protein levels by qRT-PCR and western blotting, respectively. To examine the migration and invasion capacity of studied cells exploited from wound healing assay and subsequent expression studies of glutathione-S-transferase Mu3 (GSTM3) and alfa-enolase (ENO1). Expression of GLUL significantly decreased in cells cultured at lower glucose levels compared to those at higher glucose levels. siRNA-mediated knockdown of GLUL expression in low glucose cultures significantly reduced growth, proliferation, migration, and invasion of the MCF7 cells and enhanced their apoptosis compared to the controls. Based on the results, GLUL suppression down-regulated GSTM3, a main detoxifying enzyme, and up-regulated Bax. According to the role of glycolysis as a ROS suppressor, decreased amounts of glucose could be associated with increased ROS; it can be considered an efficient involved mechanism in this study. Also, increased expression of Bax could be attributable to mTOR/AKT inhibition following GLUL repression. In conclusion, utilizing GLUL and glycolysis inhibitors might be a more effective strategy in luminal-type breast cancer therapy. See also Figure 1(Fig. 1).

Upregulation of neuronal progranulin mediates the antinociceptive effect of trimetazidine in paclitaxel-induced peripheral neuropathy: Role of ERK1/2 signaling

Neuronal progranulin (PGRN) overexpression is an endogenous adaptive pain defense following nerve injury. It allows the survival of injured neurons to block enhanced nociceptive responses. Trimetazidine (TMZ) is widely used by cardiac patients as an anti-anginal drug, reflecting its anti-ischemic property. TMZ promotes axonal regeneration of sciatic nerves after crush injury. This study explored the interplay between PGRN and extracellular signal-regulated kinases (ERK1/2) to address mechanisms underlying neuropathic pain alleviation following paclitaxel (PTX) administration. Rats were given four injections of PTX (2 mg/kg, i.p.) every other day. Two days after the last dose, rats received TMZ (25 mg/kg) with or without the ERK inhibitor, PD98059, daily for 21 days. TMZ preserved the integrity of myelinated nerve fibers, as evidenced by an obvious reduction in axonal damage biomarkers. Accordingly, it alleviated PTX-evoked thermal, cold, and mechanical hyperalgesia/allodynia. TMZ also promoted ERK1/2 phosphorylation with a profound upsurge in PGRN content. These effects were associated with a substantial increase in Notch1 receptor gene expression and a prominent anti-inflammatory effect with a marked increase in mRNA expression of secretory leukocyte protease inhibitor. Further, TMZ decreased oxidative stress and caspase-3 activity in the sciatic nerve. Conversely, co-administration of PD98059 completely abolished these beneficial effects. Thus, the robust antinociceptive effect of TMZ is largely attributed to upregulating PGRN and Notch1 receptors via ERK1/2 activation.

Combined Toxicity of Metal Nanoparticles: Comparison of Individual and Mixture Particles Effect

Toxicity of metal nanoparticles (NPs) are closely associated with increasing intracellular reactive oxygen species (ROS) and the levels of pro-inflammatory mediators. However, NP interactions and surface complexation reactions alter the original toxicity of individual NPs. To date, toxicity studies on NPs have mostly been focused on individual NPs instead of the combination of several species. It is expected that the amount of industrial and highway-acquired NPs released into the environment will further increase in the near future. This raises the possibility that various types of NPs could be found in the same medium, thereby, the adverse effects of each NP either could be potentiated, inhibited or remain unaffected by the presence of the other NPs. After uptake of NPs into the human body from various routes, protein kinases pathways mediate their toxicities. In this context, family of mitogen-activated protein kinases (MAPKs) is mostly efficient. Despite each NP activates almost the same metabolic pathways, the toxicity induced by a single type of NP is different than the case of co-exposure to the combined NPs. The scantiness of toxicological data on NPs combinations displays difficulties to determine, if there is any risk associated with exposure to combined nanomaterials. Currently, in addition to mathematical analysis (Response surface methodology; RSM), the quantitative-structure-activity relationship (QSAR) is used to estimate the toxicity of various metal oxide NPs based on their physicochemical properties and levels applied. In this chapter, it is discussed whether the coexistence of multiple metal NPs alter the original toxicity of individual NP. Additionally, in the part of "Toxicity of diesel emission/exhaust particles (DEP)", the known individual toxicity of metal NPs within the DEP is compared with the data regarding toxicity of total DEP mixture.

Association of GLP-1 receptor gene polymorphisms with sporadic Parkinson's disease in Chinese Han population

The Glucagon Like Peptide 1 Receptor (GLP1R) plays a critical role in selective death of dopaminergic neurons and development of Parkinson's disease (PD). However, little is known about genetic associations of GLP1R gene polymorphisms with PD susceptibility. Therefore, this study aimed to verify whether GLP1R polymorphisms contribute to PD risk in a Chinese Han population. We recruited 518 individuals comprising 259 sporadic PD patients and 259 healthy controls. All of the participants were genotyped for two possibly functional polymorphisms located in GLP1R (rs3765467 and rs6923761) using the Sequenom MassARRAY platform. The frequency of the rs3765467 GG genotype was significantly higher in the PD group compared with that in the control group (OR = 1.444, 95 % CI: 1.015-2.055, p =  0.041). Subgroup analysis revealed that male patients and late-onset patients with the rs3765467 GG genotype suffered an increased risk of PD compared with healthy controls (p =  0.021 and p =  0.012, respectively). However, the genotype and allele frequencies for rs6923761 were not significantly different between PD and healthy subjects. Our results indicate that the GLP1R rs3765467 GG genotype is a potential risk factor for PD, especially for male and late-onset PD patients in the Chinese Han population.

Isovaleroylbinankadsurin A ameliorates cardiac ischemia/reperfusion injury through activating GR dependent RISK signaling

Ischemia/reperfusion (I/R) injury is a pathological process caused by reperfusion. The prevention of I/R injury is of great importance as it would enhance the efficacy of myocardial infarction treatment in patients. Isovaleroylbinankadsurin A (ISBA) has been demonstrated to possess multiple bioactivities for treating diseases. However, its protective effect on myocardial I/R injury remains unknown. In this study, the cardiomyocytes hypoxia/reoxygenation (H/R) in vitro model and coronary artery ligation in vivo model were used to examine the protective effect of ISBA. Apoptosis was determined by flow cytometry and Caspase 3 activity. Protein level was determined by Western blot. The mitochondrial viability was examined with mitochondrial viability stain assay. Mitochondrial membrane potential was detected by JC-1 staining and reactive oxygen species (ROS) was stained with 2',7'-dichlorodihydrofluorescein diacetate (DCF-DA). The binding interactions between ISBA and receptors was simulated by molecular docking. Results showed that ISBA effectively protected cardiomyocytes from I/R injury in in vitro and in vivo models. It remarkably blocked the apoptosis induced by H/R injury through the mitochondrial dependent pathway. Activation of the reperfusion injury salvage kinase (RISK) pathway was demonstrated to be essential for ISBA to exert its protective effect on cardiomyocytes. Moreover, molecular docking indicated that ISBA could directly bind to glucocorticoid receptor (GR) and thus induce its activation. Furthermore, the treatment of GR inhibitor RU486 partially counteracted the protective effect of ISBA on cardiomyocytes, consistent with the results of docking.Most attractively, by activating GR dependent RISK pathway, ISBA significantly elevated the cellular anti-oxidative capacity and hence alleviated oxidative damage induced by I/R injury. In conclusion, our study proved that ISBA protected the heart from myocardial I/R injury through activating GR dependent RISK pathway and consequently inhibiting the ROS generation. It provides a valuable reference for ISBA to be developed as a candidate drug for cardiovascular diseases.

Sphingosine-1-phosphate (S1P) analog phytosphingosine-1-phosphate (P1P) improves the in vitro maturation efficiency of porcine oocytes via regulation of oxidative stress and apoptosis

Phytosphingosine-1-phosphate (P1P) is a signaling sphingolipid that regulates various physiological activities. However, little is known about the effect of P1P in the context of reproduction. Thus, we aimed to investigate the influence of P1P on oocyte maturation during porcine in vitro maturation (IVM). Here, we report the expression of S1PR1-3 among P1P receptors (S1PR1-4) in cumulus cells and oocytes. When P1P was administered at concentrations of 10, 50, 100, and 1,000 nM during IVM, the metaphase II rate was significantly increased in the 1,000 nM (1 μM) P1P treatment group. Maturation rate improvement by P1P supplementation was observed only in the presence of epidermal growth factor (EGF). Oocytes under the influence of P1P showed decreased intracellular reactive oxygen species levels but no significant differences in glutathione levels. In our molecular studies, P1P treatment upregulated gene expression involved in cumulus expansion (Has2 and EGF), antioxidant enzymes (SOD3 and Cat), and developmental competence (Oct4) while activating extracellular signal-regulated kinase1/2 and Akt signaling. P1P treatment also influenced oocyte survival by shifting the ratio of Bcl-2 to Bax while inactivating JNK signaling. We further demonstrated that oocytes matured with P1P displayed significantly higher developmental competence (cleavage and blastocyst [BL] formation rate) and greater BL quality (total cell number and the ratio of apoptotic cells) when activated via parthenogenetic activation (PA) and in vitro fertilization. Despite the low levels of endogenous P1P found in animals, exogenous P1P influenced animal reproduction, as shown by increased porcine oocyte maturation as well as preimplantation embryo development. This study and its findings are potentially relevant for both human and animal-assisted reproduction.

Liraglutide and its Neuroprotective Properties-Focus on Possible Biochemical Mechanisms in Alzheimer's Disease and Cerebral Ischemic Events

Liraglutide is a GLP-1 analog (glucagon like peptide-1) used primarily in the treatment of diabetes mellitus type 2 (DM2) and obesity. The literature starts to suggest that liraglutide may reduce the effects of ischemic stroke by activating anti-apoptotic pathways, as well as limiting the harmful effects of free radicals. The GLP-1R expression has been reported in the cerebral cortex, especially occipital and frontal lobes, the hypothalamus, and the thalamus. Liraglutide reduced the area of ischemia caused by MCAO (middle cerebral artery occlusion), limited neurological deficits, decreased hyperglycemia caused by stress, and presented anti-apoptotic effects by increasing the expression of Bcl-2 and Bcl-xl proteins and reduction of Bax and Bad protein expression. The pharmaceutical managed to decrease concentrations of proapoptotic factors, such as NF-κB (Nuclear Factor-kappa β), ICAM-1 (Intercellular Adhesion Molecule 1), caspase-3, and reduced the level of TUNEL-positive cells. Liraglutide was able to reduce the level of free radicals by decreasing the level of malondialdehyde (MDA), and increasing the superoxide dismutase level (SOD), glutathione (GSH), and catalase. Liraglutide may affect the neurovascular unit causing its remodeling, which seems to be crucial for recovery after stroke. Liraglutide may stabilize atherosclerotic plaque, as well as counteract its early formation and further development. Liraglutide, through its binding to GLP-1R (glucagon like peptide-1 receptor) and consequent activation of PI3K/MAPK (Phosphoinositide 3-kinase/mitogen associated protein kinase) dependent pathways, may have a positive impact on Aβ (amyloid beta) trafficking and clearance by increasing the presence of Aβ transporters in cerebrospinal fluid. Liraglutide seems to affect tau pathology. It is possible that liraglutide may have some stem cell stimulating properties. The effects may be connected with PKA (phosphorylase kinase A) activation. This paper presents potential mechanisms of liraglutide activity in conditions connected with neuronal damage, with special emphasis on Alzheimer's disease and cerebral ischemia.

Rapamycin treatment increases hippocampal cell viability in an mTOR-independent manner during exposure to hypoxia mimetic, cobalt chloride

BACKGROUND

Cobalt chloride (CoCl2) induces chemical hypoxia through activation of hypoxia-inducible factor-1 alpha (HIF-1α). Mammalian target of rapamycin (mTOR) is a multifaceted protein capable of regulating cell growth, angiogenesis, metabolism, proliferation, and survival. In this study, we tested the efficacy of a well-known mTOR inhibitor, rapamycin, in reducing oxidative damage and increasing cell viability in the mouse hippocampal cell line, HT22, during a CoCl2-simulated hypoxic insult.

RESULTS

CoCl2 caused cell death in a dose-dependent manner and increased protein levels of cleaved caspase-9 and caspase-3. Rapamycin increased viability of HT22 cells exposed to CoCl2 and reduced activation of caspases-9 and -3. Cells exposed to CoCl2 displayed increased reactive oxygen species (ROS) production and hyperpolarization of the mitochondrial membrane, both of which rapamycin successfully blocked. mTOR protein itself, along with its downstream signaling target, phospho-S6 ribosomal protein (pS6), were significantly inhibited with CoCl2 and rapamycin addition did not significantly lower expression further. Rapamycin promoted protein expression of Beclin-1 and increased conversion of microtubule-associated protein light chain 3 (LC3)-I into LC3-II, suggesting an increase in autophagy. Pro-apoptotic protein, Bcl-2 associated × (Bax), exhibited a slight, but significant decrease with rapamycin treatment, while its anti-apoptotic counterpart, B cell lymphoma-2 (Bcl-2), was to a similar degree upregulated. Finally, the protein expression ratio of phosphorylated mitogen-activated protein kinase (pMAPK) to its unphosphorylated form (MAPK) was dramatically increased in rapamycin and CoCl2 co-treated cells.

CONCLUSIONS

Our results indicate that rapamycin confers protection against CoCl2-simulated hypoxic insults to neuronal cells. This occurs, as suggested by our results, independent of mTOR modification, and rather through stabilization of the mitochondrial membrane with concomitant decreases in ROS production. Additionally, inhibition of caspase-9 and -3 activation and stimulation of protective autophagy reduces cell death, while a decrease in the Bax/Bcl-2 ratio and an increase in pMAPK promotes cell survival during CoCl2 exposure. Together these results demonstrate the therapeutic potential of rapamycin against hypoxic injury and highlight potential pathways mediating the protective effects of rapamycin treatment.

Icariin and mesenchymal stem cells synergistically promote angiogenesis and neurogenesis after cerebral ischemia via PI3K and ERK1/2 pathways

Mesenchymal stem cells (MSCs) are one promising candidate for regenerative therapy of ischaemic stroke through transdifferetiation and paracrine actions. Icariin (ICA) has shown great potential in improving cell activity and VEGF, BDNF secretion in vitro. Whether they will synergistically improve therapy effect on cerebral ischemia is unknown. In this study, male SD rats were subjected to transient middle cerebral artery occlusion (MCAO) followed by reperfusion and ICA/MSC treatment. Results showed that ICA and MSCs combined treatment greatly reduced brain infarction volume, improved neurologic deficits of motor and somatosensory function and neurobehavioral outcomes. The combined therapy increased expression of VEGF and BDNF to a maximum through activating PI3K and ERK1/2 pathways in the hippocampus and frontal cortex in response to transient MCAO. They notably promoted angiogenesis and neurogenesis in vivo. Thus, ICA and MSCs combined treatment may represent a feasible approach for improving the beneficial effects of stem cell therapy for cerebral ischemia.

Overexpression of G-protein-coupled receptors 65 in glioblastoma predicts poor patient prognosis

OBJECTIVE

G-protein-coupled receptors 65 (GPR65), identified as an acid-sensing receptor, is overexpressed in several malignancies and promote tumor development. Our aim was to investigate the expression and prognostic value of GPR65 in glioblastoma.

MATERIALS AND METHODS

We determined the expression of GPR65 protein using immunohistochemistry in tissue microarrays containing 11 Grade I, 107 Grade II, 47 Grade III, and 102 Grade IV gliomas and 16 normal brains. Then we evaluated its association with pathological grades, prognosis, and recurrence. The Cancer Genome Atlas (TCGA) group (N=528) was further employed to examine transcriptional level of GPR65 in glioblastoma and the correlation between GPR65 expression and clinical outcome.

RESULTS

In our cohort, GPR65 expression was positively related to glioma pathological grade (p<0.01) and elevated in glioblastoma (p<0.01). High expression of GPR65 was associated with significantly short overall survival (OS) (p=0.013) and progression-free survival (PFS) (p=0.029), and could be identified as an independent risk factor for OS of glioblastoma patients (Hazard Ratio [HR]=1.596, p=0.037). As an aiding evidence, increased GPR65 mRNA expression was also found in TCGA glioblastoma group (p<0.001) and its high level predicted a poor clinical outcome (OS, p=0.003; PFS, p=0.001).

CONCLUSION

Our findings suggest that GPR65 is overexpressed in glioblastoma and its high expression predicts unfavorable clinical outcome for patients. Targeting GPR65 may serve as a potential therapy for treating glioblastoma.

Neuroplasticity-related mechanisms underlying the antidepressant-like effects of traditional herbal medicines

Traditional herbal medicine can offer efficacious and safe alternative pharmacotherapies for depression. The ability of an herbal medicine to produce neuroadaptive processes, that enhance neuroplasticity and cellular resilience in response to chronic stress, may point to its antidepressant potential. We suggest that among many investigated herbal medicines, those that can enhance neuroplasticity may have stronger therapeutic potential. The current article presents a summary of traditional herbal medicines, which are thought to exert antidepressant-like effects in chronic stress models via neuroplasticity enhancement. Brain-derived neurotrophic factor (BDNF) is a biomarker for neuroplasticity-related mechanisms compromised in depression and recovered by conventional antidepressants, including synaptic plasticity, cell survival, neurogenesis and spine formation. We therefore presumed that if an herbal medicine up-regulates BDNF in the hippocampus and/or prefrontal cortex (PFC), its antidepressant-like effect is mediated, at least partially, via neuroplasticity-related mechanisms. Literature search was performed using the general terms depression, stress, neuroplasticity and herbal medicines. Screening of retrieved preclinical studies revealed 30 traditional herbal medicines: 8 single herbs, 15 bioactive constituents, and 7 herbal formulas. The antidepressant-like effects of these medicines were associated with reversal of chronic stress-induced impairment in neuroplasticity, most notably by BDNF up-regulation, activation of BDNF downstream signaling pathways and increase in neurogenesis in the hippocampus and/or PFC/frontal cortex. In light of the ability of these medicines to enhance neuroplasticity, we suggest that they may be suitable candidates for clinical investigation in depressed individuals. Once their efficacy, tolerability and safety will be substantiated, they may serve as natural alternatives to conventional antidepressants.

Type A monoamine oxidase and serotonin are coordinately involved in depressive disorders: from neurotransmitter imbalance to impaired neurogenesis

Type A monoamine oxidase (MAOA) catabolizes monoamine transmitters, serotonin, norepinephrine and dopamine, and plays a major role in the onset, progression and therapy of neuropsychiatric disorders. In depressive disorders, increase in MAOA expression and decrease in brain levels of serotonin and norepinephrine are proposed as the major pathogenic factors. The functional polymorphism of MAOA gene and genes in serotonin signal pathway are associated with depression. This review presents recent advance in studies on the role of MAOA in major depressive disorder and related emotional disorders. MAOA and serotonin regulate the prenatal development and postnatal maintenance of brain architecture and neurocircuit, as shown by MAOA-deficient humans and MAO knockout animal models. Impaired neurogenesis in the mature hippocampus has been proposed as "adult neurogenesis" hypothesis of depression. MAOA modulates the sensitivity to stress in the stages of brain development and maturation, and the interaction of gene-environmental factors in the early stage regulates the onset of depressive behaviors in adulthood. Vice versa environmental factors affect MAOA expression by epigenetic regulation. MAO inhibitors not only restore compromised neurotransmitters, but also protect neurons from cell death in depression through induction of anti-apoptotic Bcl-2 and prosurvival neurotrophic factors, especially brain-derived neurotrophic factor, the deficiency of which is detected in depression. This review discusses novel role of MAOA and serotonin in the pathogenesis and therapy of depressive disorders.

Inhibition of ERK activity enhances the cytotoxic effect of peroxisome proliferator-activated receptor γ (PPARγ) agonists in HeLa cells

In this study, we examined whether the peroxisome proliferator-activated receptor γ (PPARγ) agonists, ciglitazone (CGZ) and troglitazone (TGZ), induce cell death in human cervical cancer HeLa cells. The cells were treated with a range of CGZ or TGZ doses for 24 or 48 h. Low concentrations of CGZ (≤10 μM) or TGZ (≤20 μM) had no effect on cell viability whereas higher doses induced cell death in a time- and dose-dependent manner as evidenced by the detection of activated caspase-3 and PARP cleavage. Treatment with the PPARγ antagonist GW9662 followed by PPARγ agonists did not increase CGZ- or TGZ-induced cell death, indicating that PPARγ agonists induced HeLa cell death independently of PPARγ. Moreover, ERK1/2 activation was observed at a CGZ concentration of 25 μM and a TGZ concentration of 35 μM, both of which induced cell death. To elucidate the role of ERK1/2 activated by the two PPARγ agonists, the effect of U0126, an inhibitor of ERK1/2, on PPARγ-agonist-induced cell death was examined. Treatment with 10 or 20 μM U0126 followed by CGZ or TGZ induced the down-regulation of ERK1/2 activity and a decrease in Bcl-2 expression accompanied by the collapse of mitochondrial membrane potential, which in turn significantly enhanced CGZ- or TGZ-induced apoptotic cell death. Our results suggest that PPARγ agonists are capable of inducing apoptotic cell death in HeLa cells independently of PPARγ and that inhibition of ERK1/2 activity offers a strategy to enhance the cytotoxicity of PPARγ agonists in the treatment of cervical cancer.

DNA Hypermethylation of CREB3L1 and Bcl-2 Associated with the Mitochondrial-Mediated Apoptosis via PI3K/Akt Pathway in Human BEAS-2B Cells Exposure to Silica Nanoparticles

The toxic effects of silica nanoparticles (SiNPs) are raising concerns due to its widely applications in biomedicine. However, current information about the epigenetic toxicity of SiNPs is insufficient. In this study, the epigenetic regulation of low-dose exposure to SiNPs was evaluated in human bronchial epithelial BEAS-2B cells over 30 passages. Cell viability was decreased in a dose- and passage-dependent manner. The apoptotic rate, the expression of caspase-9 and caspase-3, were significantly increased induced by SiNPs. HumanMethylation450 BeadChip analysis identified that the PI3K/Akt as the primary apoptosis-related pathway among the 25 significant altered processes. The differentially methylated sites of PI3K/Akt pathway involved 32 differential genes promoters, in which the CREB3L1 and Bcl-2 were significant hypermethylated. The methyltransferase inhibitor, 5-aza, further verified that the DNA hypermethylation status of CREB3L1 and Bcl-2 were associated with downregulation of their mRNA levels. In addition, mitochondrial-mediated apoptosis was triggered by SiNPs via the downregulation of PI3K/Akt/CREB/Bcl-2 signaling pathway. Our findings suggest that long-term low-dose exposure to SiNPs could lead to epigenetic alterations.

The Neuroprotection of Liraglutide Against Ischaemia-induced Apoptosis through the Activation of the PI3K/AKT and MAPK Pathways

Glucagon-like peptide-1 (GLP-1) is an incretin hormone that increases glucose-dependent insulin secretion to reduce the glucose level. Liraglutide, a long-acting GLP-1 analogue, has been found to have neuroprotective action in various experimental models. However, the protective mechanisms of liraglutide in ischaemic stroke remain unclear. Here, we demonstrated that liraglutide significantly decreased the infarct volume, improved neurologic deficits, and lowered stress-related hyperglycaemia without causing hypoglycaemia in a rat model of middle cerebral artery occlusion (MCAO). Liraglutide inhibited cell apoptosis by reducing excessive reactive oxygen species (ROS) and improving the function of mitochondria in neurons under oxygen glucose deprivation (OGD) in vitro and MCAO in vivo. Liraglutide up-regulated the phosphorylation of protein kinase B (AKT) and extracellular signal-regulated kinases (ERK) and inhibited the phosphorylation of c-jun-NH2-terminal kinase (JNK) and p38. Moreover, the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 and/or the ERK inhibitor U0126 counteracted the protective effect of liraglutide. Taken together, these results suggest that liraglutide exerts neuroprotective action against ischaemia-induced apoptosis through the reduction of ROS and the activation of the PI3K/AKT and mitogen-activated protein kinase (MAPK) pathways. Therefore, liraglutide has therapeutic potential for patients with ischaemic stroke, especially those with Type 2 diabetes mellitus or stress hyperglycaemia.

PI3Kγ deficiency enhances seizures severity and associated outcomes in a mouse model of convulsions induced by intrahippocampal injection of pilocarpine

Phosphatidylinositol 3-kinase (PI3K) is an enzyme involved in different pathophysiological processes, including neurological disorders. However, its role in seizures and postictal outcomes is still not fully understood. We investigated the role of PI3Kγ on seizures, production of neurotrophic and inflammatory mediators, expression of a marker for microglia, neuronal death and hippocampal neurogenesis in mice (WT and PI3Kγ(-/-)) subjected to intrahippocampal microinjection of pilocarpine. PI3Kγ(-/-) mice presented a more severe status epilepticus (SE) than WT mice. In hippocampal synaptosomes, genetic or pharmacological blockade of PI3Kγ enhanced the release of glutamate and the cytosolic calcium concentration induced by KCl. There was an enhanced neuronal death and a decrease in the doublecortin positive cells in the dentate gyrus of PI3Kγ(-/-) animals after the induction of SE. Levels of BDNF were significantly increased in the hippocampus of WT and PI3Kγ(-/-) mice, although in the prefrontal cortex, only PI3Kγ(-/-) animals showed significant increase in the levels of this neurotrophic factor. Pilocarpine increased hippocampal microglial immunolabeling in both groups, albeit in the prelimbic, medial and motor regions of the prefrontal cortex this increase was observed only in PI3Kγ(-/-) mice. Regarding the levels of inflammatory mediators, pilocarpine injection increased interleukin (IL) 6 in the hippocampus of WT and PI3Kγ(-/-) animals and in the prefrontal cortex of PI3Kγ(-/-) animals 24h after the stimulus. Levels of TNFα were enhanced in the hippocampus and prefrontal cortex of only PI3Kγ(-/-) mice at this time point. On the other hand, PI3Kγ deletion impaired the increase in IL-10 in the hippocampus induced by pilocarpine. In conclusion, the lack of PI3Kγ revealed a deleterious effect in an animal model of convulsions induced by pilocarpine, suggesting that this enzyme may play a protective role in seizures and pathological outcomes associated with this condition.

Tetramethylpyrazine protects Schwann cells from ischemia-like injury and increases cell survival in cold ischemic rat nerves

Tetramethylpyrazine (TMP), a major active ingredient of Ligusticum wallichi Franchat extract (a Chinese herb), exhibits neuroprotective properties in ischemia. In this study, we assessed its protective effects on Schwann cells (SCs) by culturing them in the presence of oxygen glucose deprivation (OGD) conditions and measuring cell survival in cold ischemic rat nerves. In the OGD-induced ischemic injury model of SCs, we demonstrated that TMP treatment not only reduced OGD-induced cell viability losses, cell death, and apoptosis of SCs in a dose-dependent manner, and inhibited LDH release, but also suppressed OGD-induced downregulation of Bcl-2 and upregulation of Bax and caspase-3, as well as inhibited the consequent activation of caspase-3. In the cold ischemic nerve model, we found that prolonged cold ischemic exposure for four weeks was markedly associated with the absence of SCs, a decrease in cell viability, and apoptosis in preserved nerve segments incubated in University of Wisconsin solution (UWS) alone. However, TMP attenuated nerve segment damage by preserving SCs and antagonizing the decrease in nerve fiber viability and increase in TUNEL-positive cells in a dose-dependent manner. Collectively, our results indicate that TMP not only provides protective effects in an ischemia-like injury model of cultured rat SCs by regulating Bcl-2, Bax, and caspase-3, but also increases cell survival and suppresses apoptosis in the cold ischemic nerve model after prolonged ischemic exposure for four weeks. Therefore, TMP may be a novel and effective therapeutic strategy for preventing peripheral nervous system ischemic diseases and improving peripheral nerve storage.

ARHI overexpression induces epithelial ovarian cancer cell apoptosis and excessive autophagy

OBJECTIVE

ARHI is a maternally imprinted tumor suppressor gene that is responsible for initiating programmed cell death and inhibiting cancer cell growth. However, the influence of ARHI on epithelial ovarian cancer cell death and the underlying mechanisms behind how ARHI regulates cancer cells still require further studies.

METHODS

Epithelial ovarian cancer cells TOV112D and ES-2 were used in this in vitro study. Cell proliferation, apoptosis, and autophagy activities were compared in TOV112D and ES-2 cells transfected with ARHI vectors or control vectors. Bcl-2 siRNA was transfected into TOV112D cells to investigate the roles of Bcl-2 played in regulating apoptosis and autophagy.

RESULTS

ARHI expression was reduced in TOV112D and ES-2 cells compared with normal epithelial ovarian cells (NOE095 and HOSEpiC). Overexpressed ARHI inhibited cancer cell proliferation, whereas induced forced cell apoptosis and excessive formation of autophagosomes inhibited promoted cell death. Furthermore, we found that Bcl-2 expression moderately declined in response to ARHI overexpressing in ES-2 and TOV112D cells; meanwhile, more apoptotic cells and higher LC3 level presented after silence of Bcl-2 in TOV112D cells. Reduced Bcl-2-Beclin 1 complex were observed in ARHI overexpressing cells. Moreover, modulation of ARHI to Bcl-2 expression could be ascribed partially to the activation of PI3k/AKT pathway. The addition of LY294002 enabled to suppress Bcl-2 expression and cell proliferation.

CONCLUSIONS

The silence of ARHI expression in vitro seems to accelerate the malignant transformation of healthy ovarian cells by restraining apoptosis and autophagy. The overexpressed ARHI in TOV112D cancer cells suppresses the activation of PI3K/AKT and reduces the expression of Bcl-2, leading to enhanced cell apoptosis and autophagic cancer cell death.

Resistance to BH3 mimetic S1 in SCLC cells that up-regulate and phosphorylate Bcl-2 through ERK1/2

BACKGROUND AND PURPOSE

B cell lymphoma 2 (Bcl-2) is a central regulator of cell survival that is overexpressed in the majority of small-cell lung cancers (SCLC) and contributes to both malignant transformation and therapeutic resistance. The purpose of this work was to study the key factors that determine the sensitivity of SCLC cells to Bcl-2 homology domain-3 (BH3) mimetic S1 and the mechanism underlying the resistance of BH3 mimetics.

EXPERIMENTAL APPROACHES

Western blot was used to evaluate the contribution of Bcl-2 family members to the cellular response of SCLC cell lines to S1. Acquired resistant cells were derived from initially sensitive H1688 cells. Quantitative PCR and gene silencing were performed to investigate Bcl-2 up-regulation.

KEY RESULTS

A progressive increase in the relative levels of Bcl-2 and phosphorylated Bcl-2 (pBcl-2) characterized the increased de novo and acquired resistance of SCLC cell lines. Furthermore, acute treatment of S1 induced Bcl-2 expression and phosphorylation. We showed that BH3 mimetics, including S1 and ABT-737, induced endoplasmic reticulum (ER) stress and then activated MAPK/ERK pathway. The dual function of MAPK/ERK pathway in defining BH3 mimetics was illustrated; ERK1/2 activation leaded to Bcl-2 transcriptional up-regulation and sustained phosphorylation in naïve and acquired resistant SCLC cells. pBcl-2 played a key role in creating resistance of S1 and ABT-737 not only by sequestrating pro-apoptotic proteins, but also sequestrating a positive feedback to promote ERK1/2 activation.

CONCLUSIONS AND IMPLICATIONS

These results provide significant novel insights into the molecular mechanisms for crosstalk between ER stress and endogenously apoptotic pathways in SCLC following BH3 mimetics treatment.

Antidepressant effect of Stillen

Stillen has been used to treat patients with gastric mucosal ulcers and has an anti-inflammatory effect. It is well-known that neuro-inflammatory reactions are related to depression. Here we evaluated the antidepressant-like effect of Stillen on mice subjected to the forced swimming test (FST). Stillen and eupatilin (a major component of Stillen) significantly decreased immobility times compared with the FST control group. In the Stillen-administered group, increased levels of 5-hydroxytryptamine (serotonin) and brain-derived neurotrophic factor protein were observed in the hippocampus. Nissl bodies also increased in the hippocampus neuronal cytoplasm of the Stillen-administered group. Stillen decreased levels of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (at the mRNA and protein levels) in the hippocampus and serum, compared with the control group. In addition, the mRNA expression of estrogen receptor-β increased after Stillen administration in the hippocampus. These findings suggest that Stillen should be viewed as a candidate antidepressant.

Targeting mitochondrially mediated plasticity to develop improved therapeutics for bipolar disorder

INTRODUCTION

Bipolar disorder (BPD) is a severe illness with few treatments available. Understanding BPD pathophysiology and identifying potential relevant targets could prove useful for developing new treatments. Remarkably, subtle impairments of mitochondrial function may play an important role in BPD pathophysiology.

AREAS COVERED

This article focuses on human studies and reviews evidence of mitochondrial dysfunction in BPD as a promising target for the development of new, improved treatments. Mitochondria are crucial for energy production, generated mainly through the electron transport chain (ETC) and play an important role in regulating apoptosis and calcium (Ca²⁺) signaling as well as synaptic plasticity. Mitochondria move throughout the neurons to provide energy for intracellular signaling. Studies showed polymorphisms of mitochondria-related genes as risk factors for BPD. Postmortem studies in BPD also show decreased ETC activity/expression and increased nitrosative and oxidative stress (OxS) in patient brains. BPD has been also associated with increased OxS, Ca²⁺ dysregulation and increased proapoptotic signaling in peripheral blood. Neuroimaging studies consistently show decreased energy levels and pH in brains of BPD patients.

EXPERT OPINION

Targeting mitochondrial function, and their role in energy metabolism, synaptic plasticity and cell survival, may be an important avenue for development of new mood-stabilizing agents.

Changes in mitochondrial function are pivotal in neurodegenerative and psychiatric disorders: how important is BDNF?

The brain is at the very limit of its energy supply and has evolved specific means of adapting function to energy supply, of which mitochondria form a crucial link. Neurotrophic and inflammatory processes may not only have opposite effects on neuroplasticity, but also involve opposite effects on mitochondrial oxidative phosphorylation and glycolytic processes, respectively, modulated by stress and glucocorticoids, which also have marked effects on mood. Neurodegenerative processes show marked disorders in oxidative metabolism in key brain areas, sometimes decades before symptoms appear (Parkinson's and Alzheimer's diseases). We argue that brain-derived neurotrophic factor couples activity to changes in respiratory efficiency and these effects may be opposed by inflammatory cytokines, a key factor in neurodegenerative processes.

Sirtuin activity in dentate gyrus contributes to chronic stress-induced behavior and extracellular signal-regulated protein kinases 1 and 2 cascade changes in the hippocampus

BACKGROUND

Exposure to chronic stress produces negative effects on mood and hippocampus-dependent memory formation. Alterations in signaling cascades and histone acetylation present a mechanism of modulation of transcription that may underlie stress-dependent processes in the hippocampus critical to learning and memory and development of depressive behaviors.

METHODS

The rat model of chronic variable stress (CVS) was used to investigate the role of changes in protein acetylation and other molecular components of hippocampus-dependent memory formation and anhedonic behavior in response to CVS.

RESULTS

Chronic variable stress treatment decreased both extracellular signal-regulated protein kinases 1 and 2 activation and Bcl-2 expression in all three regions of the hippocampus that corresponded behaviorally with a decrease in memory for the novel object location task and increased anhedonia. Extracellular signal-regulated protein kinases 1 and 2 activation was not significantly affected in the amygdala and increased in the medial prefrontal cortex by CVS. Chronic variable stress had no significant effect on activation of Akt in the hippocampus. We investigated molecular and behavioral effects of infusion of the sirtuin inhibitor, sirtinol, into the dentate gyrus (DG). Sirtinol infusion into the DG prevented the CVS-mediated decrease in extracellular signal-regulated protein kinases 1 and 2 activity and Bcl-2 expression, as well as histone acetylation in the DG previously observed following CVS. This corresponded to enhanced performance on the novel object location memory task, as well as reduced anhedonic behavior.

CONCLUSIONS

These results suggest that changes in sirtuin activity contribute to changes in molecular cascades and histone acetylation within the hippocampus observed following CVS and may represent a novel therapeutic target for stress-induced depression.

[6]-shogaol attenuates neuronal apoptosis in hydrogen peroxide-treated astrocytes through the up-regulation of neurotrophic factors

Neuronal apoptosis induced by oxidative stress is a prominent feature of neurodegenerative disorders. [6]-shogaol, a bio-active compound in ginger, possesses potent anti-inflammatory actions and has recently emerged as a potential therapeutic agent for neurodegenerative disorders. However, the effects of [6]-shogaol on astroglial apoptosis following exogenously induced oxidative stress has not yet been investigated. Here, we show that the anti-apoptotic activity of [6]-shogaol in astrocytes following exposure to hydrogen peroxide (H2 O2 ) involves a marked up-regulation of neurotrophic factors such as nerve growth factor, glial cell line-derived neurotrophic factor, and brain-derived neurotrophic factor. Astrocytes co-treated with [6]-shogaol and H2 O2 for 1 h showed decrease in reactive oxygen species production compared with those only treated with H2 O2 . Moreover, [6]-shogaol counteracted the reduced expression of ERK1/2 in H2 O2 -treated astrocytes and protected these cells from oxidative stress and apoptosis by attenuating the impairment of mitochondrial function proteins such as Bcl-2 and Bcl-xL. Additionally, [6]-shogaol inhibits the expression of the apoptotic proteins Bax and caspase-3 in H2 O2 -treated astrocytes. This data suggest that following oxidative stress, [6]-shogaol protects astrocytes from oxidative damage through the up-regulating levels of neurotrophic factors. These findings provide further support for the use of [6]-shogaol as a therapeutic agent in neurodegenerative disorders.

Therapeutic concentrations of valproate but not amitriptyline increase neuropeptide Y (NPY) expression in the human SH-SY5Y neuroblastoma cell line

Neuropeptide Y (NPY) is a peptide found in the brain and autonomic nervous system, which is associated with anxiety, depression, epilepsy, learning and memory, sleep, obesity and circadian rhythms. NPY has recently gained much attention as an endogenous antiepileptic and antidepressant agent, as drugs with antiepileptic and/or mood-stabilizing properties may exert their action by increasing NPY concentrations, which in turn can reduce anxiety and depression levels, dampen seizures or increase seizure threshold. We have used human neuroblastoma SH-SY5Y cells to investigate the effect of valproate (VPA) and amitriptyline (AMI) on NPY expression at therapeutic plasma concentrations of 0.6mM and 630nM, respectively. In addition, 12-O-tetradecanoylphorbol-13-acetate (TPA) known to differentiate SH-SY5Y cells into a neuronal phenotype and to increase NPY expression through activation of protein kinase C (PKC) was applied as a positive control (16nM). Cell viability after drug treatment was tested with a 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. NPY expression was measured using immunofluorescence and quantitative RT-PCR (qRT-PCR). Results from immunocytochemistry have shown NPY levels to be significantly increased following a 72h but not 24h VPA treatment. A further increase in expression was observed with simultaneous VPA and TPA treatment, suggesting that the two agents may increase NPY expression through different mechanisms. The increase in NPY mRNA by VPA and TPA was confirmed with qRT-PCR after 72h. In contrast, AMI had no effect on NPY expression in SH-SY5Y cells. Together, the data point to an elevation of human NPY mRNA and peptide levels by therapeutic concentrations of VPA following chronic treatment. Thus, upregulation of NPY may have an impact in anti-cancer treatment of neuroblastomas with VPA, and antagonizing hypothalamic NPY effects may help to ameliorate VPA-induced weight gain and obesity without interfering with the desired central effects of VPA.

Neuroprotective activity of peripherally administered liver growth factor in a rat model of Parkinson's disease

Liver growth factor (LGF) is a hepatic mitogen purified some years ago that promotes proliferation of different cell types and the regeneration of damaged tissues, including brain tissue. Considering the possibility that LGF could be used as a therapeutic agent in Parkinson’s disease, we analyzed its potential neuroregenerative and/or neuroprotective activity when peripherally administered to unilaterally 6-hydroxydopamine (6-OHDA)-lesioned rats. For these studies, rats subjected to nigrostriatal lesions were treated intraperitoneally twice a week with LGF (5 microg/rat) for 3 weeks. Animals were sacrificed 4 weeks after the last LGF treatment. The results show that LGF stimulates sprouting of tyrosine hydroxylase-positive terminals and increases tyrosine hydroxylase and dopamine transporter expression, as well as dopamine levels in the denervated striatum of 6-OHDA-lesioned rats. In this structure, LGF activates microglia and raises tumor necrosis factor-alpha protein levels, which have been reported to have a role in neuroregeneration and neuroprotection. Besides, LGF stimulates the phosphorylation of MAPK/ERK1/2 and CREB, and regulates the expression of proteins which are critical for cell survival such as Bcl2 and Akt. Because LGF partially protects dopamine neurons from 6-OHDA neurotoxicity in the substantia nigra, and reduces motor deficits in these animals, we propose LGF as a novel factor that may be useful in the treatment of Parkinson’s disease.

Neuroprotective effects of the mood stabilizer lamotrigine against glutamate excitotoxicity: roles of chromatin remodelling and Bcl-2 induction

Lamotrigine (LTG), a phenyltriazine derivative and anti-epileptic drug, has emerged as an effective first-line treatment for bipolar mood disorder. Like the other mood stabilizers lithium and valproate, LTG also has neuroprotective properties but its exact mechanisms remain poorly defined. The present study utilized rat cerebellar granule cells (CGCs) to examine the neuroprotective effects of LTG against glutamate-induced excitotoxicity and to investigate potential underlying mechanisms. CGCs pretreated with LTG were challenged with an excitotoxic dose of glutamate. Pretreatment caused a time- and concentration-dependent inhibition of glutamate excitotoxicity with nearly full protection at higher doses (≥ 100 μm), as revealed by cell viability assays and morphology. LTG treatment increased levels of acetylated histone H3 and H4 as well as dose- and time-dependently enhanced B-cell lymphoma-2 (Bcl-2) mRNA and protein levels; these changes were associated with up-regulation of the histone acetylation and activity of the Bcl-2 promoter. Importantly, lentiviral-mediated Bcl-2 silencing by shRNA reduced both LTG-induced Bcl-2 mRNA up-regulation and neuroprotection against glutamate excitotoxicity. Finally, the co-presence of a sub-effective concentration of LTG (10 μm) with lithium or valproate produced synergistic neuroprotection. Together, our results demonstrate that the neuroprotective effects of LTG against glutamate excitotoxicity likely involve histone deacetylase inhibition and downstream up-regulation of anti-apoptotic protein Bcl-2. These underlying mechanisms may contribute to the clinical efficacy of LTG in treating bipolar disorder and warrant further investigation.

Effects of intravenous administration of human umbilical cord blood stem cells in 3-acetylpyridine-lesioned rats

Cerebellar ataxias include a heterogeneous group of infrequent diseases characterized by lack of motor coordination caused by disturbances in the cerebellum and its associated circuits. Current therapies are based on the use of drugs that correct some of the molecular processes involved in their pathogenesis. Although these treatments yielded promising results, there is not yet an effective therapy for these diseases. Cell replacement strategies using human umbilical cord blood mononuclear cells (HuUCBMCs) have emerged as a promising approach for restoration of function in neurodegenerative diseases. The aim of this work was to investigate the potential therapeutic activity of HuUCBMCs in the 3-acetylpyridine (3-AP) rat model of cerebellar ataxia. Intravenous administered HuUCBMCs reached the cerebellum and brain stem of 3-AP ataxic rats. Grafted cells reduced 3-AP-induced neuronal loss promoted the activation of microglia in the brain stem, and prevented the overexpression of GFAP elicited by 3-AP in the cerebellum. In addition, HuUCBMCs upregulated the expression of proteins that are critical for cell survival, such as phospho-Akt and Bcl-2, in the cerebellum and brain stem of 3-AP ataxic rats. As all these effects were accompanied by a temporal but significant improvement in motor coordination, HuUCBMCs grafts can be considered as an effective cell replacement therapy for cerebellar disorders.

[Antiepileptic prophylaxis for elective neurosurgery]

In tumoral surgery, the risk factors for perioperative epilepsy can be roughly grouped into two categories: those related to the preoperative patient's conditions (type and location of the tumors, their impact on the surrounding brain…) and those specifically related to surgery (cerebral edema, parenchymal hematoma, surgical approach, complete or incomplete resection...). The first category is supposed to be responsible for preoperative and late postoperative epilepsy, while the second would be more related to the risk of epilepsy in the first postoperative week (or may be even in the first 48hours). It is well accepted (but not always respected) by the neuro-oncologists that there is no indication for preventive antiepileptic drugs (AED) in a patient with a brain tumor that has never presented seizure. However, every seizure crisis must be treated medically. Neurosurgical procedure (which is also a key factor for controlling epilepsy when it occurs. The AED should then be maintained as appropriate. In the absence of preoperative treatment, it has never been shown that prophylactic AED significantly decreases the incidence of postoperative seizures, early or late. Yet, the opposite has not been shown neither, and many groups use AED despite the risk of side effects and an uncertain risk-benefit ratio. Currently, postoperative epilepsy is much less frequent than it was 20 or 30years ago, and the risk of AED side effects also decreases with the latest generation of molecules (such as levetiracetam). So, AED risks and benefits tend to diminish in parallel, but their relationship is still to be assessed. In practice, a modern attitude would restrict prophylactic AED use to the higher risk patients (preoperative epilepsy, temporal astrocytoma, the extent of edema and mass effect...). A drug of last generation should be used, starting one week before surgery. The duration of the treatment should be limited to one week postoperatively in the absence of seizure.

Impaired mitochondrial function in psychiatric disorders

Major psychiatric illnesses such as mood disorders and schizophrenia are chronic, recurrent mental illnesses that affect the lives of millions of individuals. Although these disorders have traditionally been viewed as 'neurochemical diseases', it is now clear that they are associated with impairments of synaptic plasticity and cellular resilience. Although most patients with these disorders do not have classic mitochondrial disorders, there is a growing body of evidence to suggest that impaired mitochondrial function may affect key cellular processes, thereby altering synaptic functioning and contributing to the atrophic changes that underlie the deteriorating long-term course of these illnesses. Enhancing mitochondrial function could represent an important avenue for the development of novel therapeutics and also presents an opportunity for a potentially more efficient drug-development process.

Antipsychotics in the treatment of bipolar disorder

Atypical antipsychotics have an important role in the acute and maintenance treatment of bipolar disorder. While robust evidence supports the efficacy of these agents in the treatment of mania and in the prevention of manic relapse, few atypical antipsychotics have shown efficacy in the treatment or prevention of depressive episodes. These agents pose a lower risk of extrapyramidal side effects compared to typical neuroleptics, but carry a significant liability for weight gain and other metabolic side effects such as hyperglycemia and hyperlipidemia. More comparative effectiveness studies are needed to assess the optimal treatment regimens, including the relative benefits and risks of antipsychotics versus mood stabilizers. The exploration of the molecular mechanisms of antipsychotics has helped to shed further light on the underlying neurobiology of bipolar disorder, since these compounds target systems thought to be key to the pathophysiology of bipolar disorder. In addition to modulating monoaminergic neurotransmission, atypical antipsychotics appear to share properties with mood-stabilizing agents known to alter intracellular signal transduction leading to changes in neuronal activity and gene expression. Atypical antipsychotic drugs have been shown to exhibit neuroprotective properties that are mediated by upregulation of trophic and cellular resilience factors. Building on our understanding of existing therapeutics, especially as it relates to underlying disease pathology, newer "plasticity enhancing" strategies hold promise for future treatments of bipolar disorder.

Cell death is induced by ciglitazone, a peroxisome proliferator-activated receptor γ (PPARγ) agonist, independently of PPARγ in human glioma cells

Peroxisome proliferator-activated receptor γ (PPARγ) regulates multiple signaling pathways, and its agonists induce apoptosis in various cancer cells. However, their role in cell death is unclear. In this study, the relationship between ciglitazone (CGZ) and PPARγ in CGZ-induced cell death was examined. At concentrations of greater than 30 μM, CGZ, a synthetic PPARγ agonist, activated caspase-3 and induced apoptosis in T98G cells. Treatment of T98G cells with less than 30 μM CGZ effectively induced cell death after pretreatment with 30 μM of the PPARγ antagonist GW9662, although GW9662 alone did not induce cell death. This cell death was also observed when cells were co-treated with CGZ and GW9662, but was not observed when cells were treated with CGZ prior to GW9662. In cells in which PPARγ was down-regulated cells by siRNA, lower concentrations of CGZ (<30 μM) were sufficient to induce cell death, although higher concentrations of CGZ (≥30 μM) were required to induce cell death in control T98G cells, indicating that CGZ effectively induces cell death in T98G cells independently of PPARγ. Treatment with GW9662 followed by CGZ resulted in a down-regulation of Akt activity and the loss of mitochondrial membrane potential (MMP), which was accompanied by a decrease in Bcl-2 expression and an increase in Bid cleavage. These data suggest that CGZ is capable of inducing apoptotic cell death independently of PPARγ in glioma cells, by down-regulating Akt activity and inducing MMP collapse.

Pigment epithelium-derived factor (PEDF) protects cortical neurons in vitro from oxidant injury by activation of extracellular signal-regulated kinase (ERK) 1/2 and induction of Bcl-2

Mitigating oxidative stress-induced damage is critical to preserve neuronal function in diseased or injured brains. This study explores the mechanisms contributing to the neuroprotective effects of pigment epithelium-derived factor (PEDF) in cortical neurons. Cultured primary neurons are exposed to PEDF and H₂O₂ as well as inhibitors of phosphoinositide-3 kinase (PI3K) or extracellular signal-regulated kinase 1/2 (ERK1/2). Neuronal survival, cell death and levels of caspase 3, PEDF, phosphorylated ERK1/2, and Bcl-2 are measured. The data show cortical cultures release PEDF and that H₂O₂ treatment causes cell death, increases activated caspase 3 levels and decreases release of PEDF. Exogenous PEDF induces a dose-dependent increase in Bcl-2 expression and neuronal survival. Blocking Bcl-2 expression by siRNA reduced PEDF-induced increases in neuronal survival. Treating cortical cultures with PEDF 24 h before H₂O₂ exposure mitigates oxidant-induced decreases in neuronal survival, Bcl-2 expression, and phosphorylation of ERK1/2 and also reduces elevated caspase 3 level and activity. PEDF pretreatment effect on survival is blocked by inhibiting ERK or PI3K. However, only inhibition of ERK reduced the ability of PEDF to protect neurons from H₂O₂-induced Bcl-2 decrease and neuronal death. These data demonstrate PEDF-mediated neuroprotection against oxidant injury is largely mediated via ERK1/2 and Bcl-2 and suggest the utility of PEDF in preserving the viability of oxidatively challenged neurons.

Valproic acid inhibits neural progenitor cell death by activation of NF-κB signaling pathway and up-regulation of Bcl-XL

Background

At the beginning of neurogenesis, massive brain cell death occurs and more than 50% of cells are eliminated by apoptosis along with neuronal differentiation. However, few studies were conducted so far regarding the regulation of neural progenitor cells (NPCs) death during development. Because of the physiological role of cell death during development, aberration of normal apoptotic cell death is detrimental to normal organogenesis.

Apoptosis occurs in not only neuron but also in NPCs and neuroblast. When growth and survival signals such as EGF or LIF are removed, apoptosis is activated as well as the induction of differentiation. To investigate the regulation of cell death during developmental stage, it is essential to investigate the regulation of apoptosis of NPCs.

Methods

Neural progenitor cells were cultured from E14 embryonic brains of Sprague-Dawley rats. For in vivo VPA animal model, pregnant rats were treated with VPA (400 mg/kg S.C.) diluted with normal saline at E12. To analyze the cell death, we performed PI staining and PARP and caspase-3 cleavage assay. Expression level of proteins was investigated by Western blot and immunocytochemical assays. The level of mRNA expression was investigated by RT-PCR. Interaction of Bcl-XL gene promoter and NF-κB p65 was investigated by ChIP assay.

Results

In this study, FACS analysis, PI staining and PARP and caspase-3 cleavage assay showed that VPA protects cultured NPCs from cell death after growth factor withdrawal both in basal and staurosporine- or hydrogen peroxide-stimulated conditions. The protective effect of prenatally injected VPA was also observed in E16 embryonic brain. Treatment of VPA decreased the level of IκBα and increased the nuclear translocation of NF-κB, which subsequently enhanced expression of anti-apoptotic protein Bcl-XL.

Conclusion

To the best of our knowledge, this is the first report to indicate the reduced death of NPCs by VPA at developmentally critical periods through the degradation of IκBα and the activation of NF-κB signaling. The reduced NPCs death might underlie the neurodevelopmental defects collectively called fetal valproate syndrome, which shows symptoms such as mental retardation and autism-like behavior.

Interaction networks of lithium and valproate molecular targets reveal a striking enrichment of apoptosis functional clusters and neurotrophin signaling

The overall neurobiological mechanisms by which lithium and valproate stabilize mood in bipolar disorder patients have yet to be fully defined. The therapeutic efficacy and dissimilar chemical structures of these medications suggest that they perturb both shared and disparate cellular processes. To investigate key pathways and functional clusters involved in the global action of lithium and valproate, we generated interaction networks formed by well-supported drug targets. Striking functional similarities emerged. Intersecting nodes in lithium and valproate networks highlighted a strong enrichment of apoptosis clusters and neurotrophin signaling. Other enriched pathways included MAPK, ErbB, insulin, VEGF, Wnt and long-term potentiation indicating a widespread effect of both drugs on diverse signaling systems. MAPK1/3 and AKT1/2 were the most preponderant nodes across pathways suggesting a central role in mediating pathway interactions. The convergence of biological responses unveils a functional signature for lithium and valproate that could be key modulators of their therapeutic efficacy.

Postoperative seizures following the resection of convexity meningiomas: are prophylactic anticonvulsants indicated?

Object

Seizures in the perioperative period are a well-recognized clinical entity in the setting of brain tumor surgery. At present, the suitability of antiepileptic prophylaxis in patients following brain tumor surgery is unclear, especially in those without prior seizures. Given the paucity of tumor-type and site-specific data, the authors evaluated the incidence of postoperative seizures in patients with convexity meningiomas and no prior seizures.

Methods

The authors identified 180 patients with no preoperative history of seizures who underwent resection of a convexity meningioma. Some patients received antiepileptic prophylaxis for 7 days postoperatively while others did not, based on the practice patterns of different attendings. The rates of clinically evident seizures in the first 3–4 weeks after surgery were compared.

Results

Patients who received antiepilepsy drugs (129 patients) did not significantly differ from those who did not (51 patients) in terms of age, sex, WHO tumor grade, extent of resection, rate of previous cranial surgery or radiation therapies, or use of preoperative embolization. There was a single new postoperative seizure in the entire cohort, yielding a new seizure rate of 1.9% in patients not on antiepileptic prophylaxis compared with 0% in patients on antiepileptics (p = not significant).

Conclusions

While it is thought that the routine use of prophylactic antiepileptics may prevent new seizures in patients undergoing surgery for a convexity meningioma, the rate of new seizures in untreated patients is probably very low. Data in this study call into question whether the cost and side effects of these medications are worth the small benefit their administration may confer.