Valproate: past, present, and future

Neuroleptic Malignant Syndrome Associated with Valproate in an Adolescent

Neuroleptic malignant syndrome (NMS) is a life-threatening idiosyncratic reaction that usually occurs after the administration of antipsychotic drugs. Antidepressants, benzodiazepines, and antiepileptic drugs are also suggested to be associated with NMS. It is believed to result from a dopaminergic blockade in the central nervous system. NMS is manifested by hyperthermia, muscle rigidity, autonomic dysfunction, altered mental status, leukocytosis, and elevated serum creatinine phosphokinase. Valproate is commonly used in the treatment of many psychiatric and neurologic disorders. Valproate can precipitate NMS, especially when used with antipsychotic drugs concurrently. A 17-year-old male patient, who presented with fever, muscular rigidity, confusion, sweating, and tachycardia was admitted to the emergency room. He had been taking only valproate for the last two months for bipolar disorder. His laboratory analyses revealed raised serum hepatic enzymes, creatinine phosphokinase, and myoglobin levels. Considering fever, rigidity, autonomic dysfunction, cognitive alteration, and high creatinine phosphokinase levels, the patient was diagnosed with NMS. In this paper, we aim to discuss the association between valproate and NMS.

Comparison of LC-MS/MS vs chemiluminescent microparticle immunoassay in measuring the valproic acid concentration in plasma of epilepsy patients in a new perspective

OBJECTIVES

This study was designed to compare the performance of LC-MS/MS with chemiluminescent microparticle immunoassay (CMIA) for determination of VPA in epilepsy patients in the perspective of metabolites' hepatotoxicity.

METHOD

Samples were collected and then analyzed using both LC-MS/MS and CMIA. A LO2 cells (normal human hepatic cells) experiment was carried out to confirm VPA metabolites' hepatotoxicity using AST(Aspertate Aminotransferase, AST), ALT(Alanine aminotransferase, ALT) and LDH(lactate dehydrogenase, LDH) in supernate as index.

RESULTS

The regression equation analysis showed as LC-MS/MS=1.0094CMIA-1.8937, with the concordance correlation coefficient of 0.9700, and the CUSUM test proved no significant deviation from linearity (P>.05). CMIA compared to LC-MS/MS gave a positive bias of 1.2 μg/mL. In LO2 experiment, VPA and its metabolites groups showed an obvious increment of AST, ALT, and LDH in supernate.

CONCLUSION

The LC-MS/MS is largely consistent with the CMIA in analytical time and quantification ability for VPA, but the LC-MS/MS can simultaneously determinate VPA and its metabolites in plasma, and is also a higher cost-efficiency method in consideration of toxic metabolites monitoring. The overestimation of VPA by CMIA showed no clinical significance. The metabolites 3-OH-VPA and 5-OH-VPA damage the LO2 cells and the results presented a statistical significance (P<.05). It is vital to monitor the metabolites' concentrations for VAP's clinical safety application, and now is the occasion that laboratory and clinic consider the LC-MS/MS method as a more advantageous alternative to CMIA method in therapeutic monitoring of VPA.

Novel valproic aminophenol amides with enhanced glial cell viability effect

In this work, ortho-aminophenols were attached to valproic acid, resulting in seven novel anticancer drug prototypes.

Valproate Reduces Delayed Brain Injury in a Rat Model of Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE

Spreading depolarizations (SDs) may contribute to delayed cerebral ischemia after subarachnoid hemorrhage (SAH). We tested whether SD-inhibitor valproate reduces brain injury in an SAH rat model with and without experimental SD induction.

METHODS

Rats were randomized in a 2×2 design and pretreated with valproate (200 mg/kg) or vehicle for 4 weeks. SAH was induced by endovascular puncture of the right internal carotid bifurcation. One day post-SAH, brain tissue damage was measured with T₂-weighted magnetic resonance imaging, followed by cortical application of 1 mol/L KCl (to induce SDs) or NaCl (no SDs). Magnetic resonance imaging was repeated on day 3 followed by histology to confirm neuronal death. Neurological function was measured with an inclined slope test.

RESULTS

In the groups with KCl application, lesion growth between days 1 and 3 was 57±73 mm3 in the valproate-treated versus 237±232 mm3 in the vehicle-treated group. In the groups without SD induction, lesion growth in the valproate- and vehicle-treated groups was 8±20 mm3 versus 27±52 mm3. On fitting a 2-way analysis of variance model, we found a significant interaction effect between treatment and KCl/NaCl application of 161 mm3 (P=0.04). Number and duration of SDs, mortality, and neurological function were not statistically significantly different between groups. Lesion growth on magnetic resonance imaging correlated to histological infarct volume (Spearman's rho =0.83; P=0.0004), with areas of lesion growth exhibiting reduced neuronal death compared with primary lesions.

CONCLUSIONS

In our rat SAH model, valproate treatment significantly reduced brain lesion growth after KCl application. Future studies are needed to confirm that this protective effect is based on SD inhibition.

Valproic acid reduces hair loss and improves survival in patients receiving temozolomide-based radiation therapy for high-grade glioma

PURPOSE

Valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, is also used to manage seizures in glioblastoma patients. HDAC inhibitors can protect normal cells and tissues from the deleterious effects of radiotherapy, and VPA is reported to improve the survival of glioblastoma patients receiving chemoradiation therapy. VPA also promotes hair growth, and thus has the potential to reduce the radiotherapy side effect of hair loss while improving the survival of patients with glioblastoma. The purpose of this study was to determine whether VPA use during radiotherapy for high-grade glioma is associated with decreased side effects of radiotherapy and an improvement in overall survival (OS) and progression-free survival (PFS).

METHODS

Medical records of 112 patients with high-grade glioma were retrospectively reviewed. We grouped patients by VPA use or non-use during radiotherapy, and evaluated hair loss, OS, and PFS.

RESULTS

The radiation dose and fractionation at the onset of hair loss were 4 Gy and two fractions higher, respectively, in the VPA group compared with the VPA non-use group (P < 0.01). Median OS was 42.2 and 20.3 months in the VPA use and non-use groups, respectively (P < 0.01; hazard ratio [HR], 0.36; 95% confidence interval [CI], 0.18-0.74). Median PFS was 22.7 and 11.0 months in the VPA use and non-use groups, respectively (P = 0.099; HR, 0.62; 95% CI, 0.36-1.09).

CONCLUSIONS

VPA use during radiotherapy for glioma is associated with delayed hair loss and improvement in survival. Hair loss prevention benefits patients suffering from the deleterious effects of radiation.

Upregulation of CD54 and downregulation of HLA‑ABC contribute to the novel enhancement of the susceptibility of HL-60 cells to NK cell-mediated cytolysis induced by ATRA plus VPA

Enhancement of the susceptibility of HL-60 cells to NK cell-mediated cytolysis induced by all-trans-retinoic acid (ATRA) plus valproate (VPA) was evaluated. In addition to the synergistic effect of ATRA plus VPA on HL-60 cells, the optimal concentration of 1 mM VPA plus 0.5 µM ATRA increased the cytotoxic sensitivity of HL-60 cells to NK cells. The expression of the activated receptors NKp30 and NKG2D on NK-92 cells was higher compared with the levels noted for the other receptors, and the expression of NKG2D ligands MICA/B on HL-60 cells was not significantly upregulated in the ATRA plus VPA goup compared with the control. Moreover, it was observed that the ligands of NKp30 on HL-60 cells presented the same variation trend. As to the co-stimulatory and adhesion molecules on NK-92 and their ligands on HL-60 cells post exposure to ATRA and VPA alone or their combination, there was no obvious change in the expression of CD112, CD48 and CD70 on the HL-60 cells. However, the expression of CD54 on HL-60 cells was significantly upregulated. In contrast, the expression of NKG2A ligands HLA-ABC on HL-60 cells was obviously downregulated. In addition, the expression of HLA-E on the HL-60 cells in the group treated with ATRA plus VPA was not significantly increased. In conclusion, the combination of VPA and ATRA not only induced the differentiation of HL-60 cells, but also induced enhancement of the sensitivity of HL-60 cells to NK cells by downregulating the expression of HLA-ABC and upregulating the expression of CD54, but not MICA/MICB. The results provide experimental and theoretical basis for the clinical combination of a low-dose of ATRA plus VPA for the treatment of leukemia.

Potential role of selected antiepileptics used in neuropathic pain as human GABA transporter isoform 1 (GAT1) inhibitors-Molecular docking and pharmacodynamic studies

The chemical interaction of nine antiepileptic drugs (tiagabine, gabapentin, pregabalin, lamotrigine, zonisamide, valproic acid, valpromide, vigabatrin, progabide) and two endogenous metabolites (4-aminobutanoic acid, 4-hydroxybutanoic acid) with a model of human GABA transporter 1 (hGAT1) is described using the molecular docking method. To establish the role of hGAT1 in chronic pain, tiagabine, a selective hGAT1 inhibitor, was assessed in the in vivo experiments for its antiallodynic properties in two mouse models of neuropathic pain. Docking analyses performed in this study provided the complex binding energies, specific hydrogen bond components, and hydrogen bond properties such as energies, distances and angles. The data of the docking studies strongly support the assumption that the antiepileptic and analgesic actions of the studied drugs can be at least in part related to the strength of their chemical interactions with hGAT1. In vivo experiments with tiagabine confirmed the involvement of hGAT1 in the regulation of the mechanical nociceptive threshold in neuropathic pain.

Effects of Lycopene and Sodium Valproate on Pentylenetetrazol-Induced Kindling in Mice

Sodium valproate and tomato extract have been studied in different experimental models of epilepsy individually. The aim of the present study was to evaluate the effect of lycopene on the antiepileptic effects of sodium valproate against pentylenetetrazol-induced kindling in mice. Swiss albino mice of either sex were randomly divided into 5 groups, with each group containing 8 mice. These groups were treated with pentylenetetrazol (45 mg/kg on days 8, 10, and 12 and 70 mg/kg on day 14 day, i.p.); sodium valproate (200 mg/kg, p.o.) + pentylenetetrazol; lycopene (2 mg/kg, p.o.) + sodium valproate (200 mg/kg, p.o.) + pentylenetetrazol; and lycopene (4 mg/kg, p.o.) + sodium valproate (200 mg/kg, p.o.) + pentylenetetrazol, for 14 days, respectively. After treatment, the animals were observed for 30 minutes for behavioral analysis. Subsequently, the animals were sacrificed, and their brain was removed for the biochemical estimations of thiobarbituric acid reactive substances, catalase, superoxide dismutase activity, reduced glutathione, and gamma-aminobutyric acid. Significant pentylenetetrazol-induced seizure was characterized by alteration in the seizure score and latency as well as a significant increase in the levels of brain thiobarbituric acid reactive substances and a significant decrease in reduced glutathione, catalase, superoxide dismutase, and gamma-aminobutyric acid levels. Treatment with sodium valproate and lycopene significantly restored the seizure score, latency, thiobarbituric acid reactive substance, reduced glutathione, catalase, superoxide dismutase, and gamma-aminobutyric acid levels near to normal compared to pentylenetetrazol. The present study provides experimental evidence that a combination therapy of lycopene along with sodium valproate attenuated seizure and oxidative stress against pentylenetetrazol-induced kindling in mice.

Histone deacetylase inhibitor pracinostat in doublet therapy: a unique strategy to improve therapeutic efficacy and to tackle herculean cancer chemoresistance

Context Histone deacetylase inhibitors (HDACi) have shown promising results in neurodegeneration and cancer. Hydroxamate HDACi, including vorinostat, have shown encouraging results in haematological malignancies, but the poor pharmacokinetic of these inhibitors leads to insufficient tumour concentration limiting their application against solid malignancies. Objective This article deals with novel HDAC inhibitor pracinostat (SB939) and delineates its therapeutic role in solid and haematological malignancies. The article provides rigorous details about the underlying molecular mechanisms modulated by pracinostat to exert cytotoxic effect. The article further highlights the doublet therapy that may be used to tackle monotonous cancer chemoresistance. Methods Both old and the latest literature on pracinostat was retrieved from diverse sources, such as PubMed, Science Direct, Springer Link, general Google search using both pracinostat and SB939 keywords in various ways: after thorough evaluation the topic which can fulfil the current gap was chosen. Results Pracinostat shows potent anticancer activity against both solid and haematological malignancies compared to the FDA-approved drug vorinostat. This marvellous inhibitor has better physicochemical, pharmaceutical and pharmacokinetic properties than the defined inhibitor vorinostat. Pracinostat has  >100-fold more affinity towards HDACs compared to other zinc-dependent metalloenzymes and shows maximum efficacy when used in doublet therapy. Conclusion Pracinostat shows potent anticancer activity even against therapeutically challenging cancers when used in doublet therapy. However, the triplet combination studies of the defined inhibitor that may prove even more beneficial are still undone, emphasizing the desperate need of further research in the defined gap.

Valproic Acid and Hepatic Steatosis: A Possible Link? About a Case Report

BACKGROUND

Valproic acid is a mood-stabilizing anticonvulsant. Hepatic injuries are among the occasionally observed adverse effects of this medication.

CASE PRESENTATION

We present the case of a 47-year-old man who had bipolar disorder for ten years and treated with valproic acid. He demonstrated elevated serum aminotransferases and ultrasonography revealed that hepatomegaly was suggestive of hepatic steatosis.

CONCLUSION

This case report stresses the importance of a complete drug history and the need for clinicians to be aware of the delayed onset of hepatic injuries.

N-(2-hydroxyphenyl)-2-propylpentanamide, a valproic acid aryl derivative designed in silico with improved anti-proliferative activity in HeLa, rhabdomyosarcoma and breast cancer cells

Epigenetic alterations are associated with cancer and their targeting is a promising approach for treatment of this disease. Among current epigenetic drugs, histone deacetylase (HDAC) inhibitors induce changes in gene expression that can lead to cell death in tumors. Valproic acid (VPA) is a HDAC inhibitor that has antitumor activity at mM range. However, it is known that VPA is a hepatotoxic drug. Therefore, the aim of this study was to design a set of VPA derivatives adding the arylamine core of the suberoylanilide hydroxamic acid (SAHA) with different substituents at its carboxyl group. These derivatives were submitted to docking simulations to select the most promising compound. The compound 2 (N-(2-hydroxyphenyl)-2-propylpentanamide) was the best candidate to be synthesized and evaluated in vitro as an anti-cancer agent against HeLa, rhabdomyosarcoma and breast cancer cell lines. Compound 2 showed a better IC₅₀ (μM range) than VPA (mM range) on these cancer cells. And also, 2 was particularly effective on triple negative breast cancer cells. In conclusion, 2 is an example of drugs designed in silico that show biological properties against human cancer difficult to treat as triple negative breast cancer.

Novel molecular triggers underlie valproate-induced liver injury and its alleviation by the omega-3 fatty acid DHA: role of inflammation and apoptosis

Background/Aim

Hepatic injury is a hallmark adverse reaction to Valproate (VPA), a common used drug in the management of numerous CNS disorders, including epilepsy. DHA has a myriad of health benefits, including renal- and hepato-protective effects. Unfortunately, however, the underpinnings of such liver-pertinent VPA- and DHA-actions remain largely undefined. Accordingly, this study attempted to unveil the cellular and molecular triggers whereby VPA evokes, while DHA abates, hepatotoxicity.

Methods

We evaluated activity and/or expression of cellular markers of oxidative stress, inflammation, and apoptosis in rat liver, following treatment with VPA (500 mg/kg/day) with and without concurrent treatment with DHA (250 mg/kg/day) for two weeks.

Results and conclusion

VPA promoted hepatic oxidative stress as evidenced by enhancing activity/expression of NADPH-oxidase and its subunits, a ROS-generator, and by accumulation of lipid-peroxides. Moreover, VPA enhanced hepatic phosphorylation/activation of mitogen-activated protein kinase (MAPK), and expression of cyclooxygenase-2(COX-2), as proinflammatory signals. Besides, VPA promoted hepatocellular apoptosis, as attested by enhanced expression of cleaved caspase-9 and increased number of TUNEL-positive hepatocytes. Lastly, VPA upregulated levels of hypoxia-inducible factor-1-alpha (HIF-1α), a multifaceted modulator of hepatocytic biology, and activity of its downstream antioxidant enzyme heme-oxygenase-1(HO-1). These changes were significantly blunted by co-administration of DHA. Our findings demonstrate that VPA activated NADPH-oxidase and HIF-1α to induce oxidative-stress and hypoxia as initiators of hepatic injury. These changes were further aggravated by up-regulation of inflammatory (MAPK and COX-2) and apoptotic cascades, but could be partly lessened by HO-1 activation. Concurrent administration of DHA mitigated all VPA-induced anomalies.

Transcriptional regulation of E-cadherin and oncoprotein E7 by valproic acid in HPV positive cell lines

OBJECTIVES

Valproic acid (VPA) has proven to be as one of the most promising useful drug with anticancer properties. In this study, we investigate the VPA effects on E-cadherin expression in HeLa, TC1, MKN45, and HCT116 cell lines. This study assesses the effects of VPA on human papillomavirus E7 expression in HPV positive cell lines.

MATERIALS AND METHODS

Cell lines were treated by 2 mmol/l VPA and expression of E-cadherin and E7 was analyzed by quantitative real-time PCR. Student's t test and ANOVA were used to determine changes in expression levels.

RESULTS

The results revealed that mean of E-cadherin expression is increased by VPA 1.8 times in HCT116 and MKN45 cell lines, also the mean of E-cadherin mRNA levels is up-regulated 2.9 times in HeLa and TC1 cell lines. So, E-cadherin augmentation induced by VPA in HeLa and TC-1, HPV positive cell lines, is higher than HPV negative cell lines MKN45 and HCT116. The mean of HPV E7 expression is decreased by VPA, 4.6 times in in HeLa and TC-1 cell lines.

CONCLUSION

This study demonstrates that re-expression of E-cadherin by VPA in HPV positive cell lines is more than HPV negative cell lines. Whereas, HPV E7 reduces the expression of E-cadherin, reduction of HPV E7 expression by VPA is related to more augmentation of E-cadherin in HPV positive cell lines. So, this study demonstrates that VPA has more anticancer properties in HPV positive cell lines, and could potentially be a promising candidate for cervical cancer treatment.

Histone deacetylase inhibitor givinostat: the small-molecule with promising activity against therapeutically challenging haematological malignancies

Histone acetyl transferases and histone deacetylases (HDACs) are counteracting epigenetic enzymes regulating the turnover of histone acetylation thereby regulating transcriptional events in a precise manner. Deregulation of histone acetylation caused by aberrant expression of HDACs plays a key role in tumour onset and progression making these enzymes as candidate targets for anticancer drugs and therapy. Small-molecules namely histone deacetylase inhibitors (HDACi) modulating the biological function of HDACs have shown multiple biological effects including differentiation, cell cycle arrest and apoptosis in tumour models. HDACi in general have been described in plethora of reviews with respect to various cancers. However, no review article is available describing thoroughly the role of inhibitor givinostat (ITF2357 or [6-(diethylaminomethyl) naphthalen-2-yl] methyl N-[4-(hydroxycarbamoyl) phenyl] carbamate) in haematological malignancies. Thus, the present review explores the intricate role of novel inhibitor givinostat in the defined malignancies including multiple myeloma, acute myelogenous leukaemia, Hodgkin's and non-Hodgkin's lymphoma apart from myeloproliferative neoplasms. The distinct molecular mechanisms triggered by this small-molecule inhibitor in these cancers to exert cytotoxic effect have also been dealt with. The article also highlights the combination strategy that can be used for enhancing the therapeutic efficiency of this inhibitor in the upcoming future.

Neuroinformatics analyses reveal GABAt and SSADH as major proteins involved in anticonvulsant activity of valproic acid

The unequivocal hypotheses about anticonvulsant activity of valproic acid (VPA) have always been a basic hurdle in designing next generation neurotherapeutics, particularly the anti-epileptic drugs. The present study reports about a comprehensive in-silico investigation into qualitative and quantitative binding of VPA and corresponding natural ligands of four major enzymes involved in neurotransmissions, namely-GABA transaminase (GABAt), α-keto glutarate dehydrogenase (α-KGDH), Succinate Semialdehyde dehydrogenase (SSADH) and Glutamate Decarboxylase (GAD), respectively. The molecular docking analyses revealed that VPA inhibits GABAt and α-KGDH through allosteric while SSADH through competitive mode of binding. There is an observed elevation in binding of glutamate over GAD in the presence of VPA. The docking inhibition constant (Ki) of VPA to all the studied enzymatic receptors were observed to be well below the therapeutic concentration of VPA in blood, except for α-KGDH, thus favouring GABAergic over glutamatergic mode of anticonvulsant activity of VPA. The report is probably the first comprehensive in-silico molecular study about VPA action.

Inverse Association between Sodium Channel-Blocking Antiepileptic Drug Use and Cancer: Data Mining of Spontaneous Reporting and Claims Databases

PURPOSE

Voltage-gated sodium channels (VGSCs) are drug targets for the treatment of epilepsy. Recently, a decreased risk of cancer associated with sodium channel-blocking antiepileptic drugs (AEDs) has become a research focus of interest. The purpose of this study was to test the hypothesis that the use of sodium channel-blocking AEDs are inversely associated with cancer, using different methodologies, algorithms, and databases.

METHODS

A total of 65,146,507 drug-reaction pairs from the first quarter of 2004 through the end of 2013 were downloaded from the US Food and Drug Administration Adverse Event Reporting System. The reporting odds ratio (ROR) and information component (IC) were used to detect an inverse association between AEDs and cancer. Upper limits of the 95% confidence interval (CI) of < 1 and < 0 for the ROR and IC, respectively, signified inverse associations. Furthermore, using a claims database, which contains 3 million insured persons, an event sequence symmetry analysis (ESSA) was performed to identify an inverse association between AEDs and cancer over the period of January 2005 to May 2014. The upper limit of the 95% CI of adjusted sequence ratio (ASR) < 1 signified an inverse association.

RESULTS

In the FAERS database analyses, significant inverse associations were found between sodium channel-blocking AEDs and individual cancers. In the claims database analyses, sodium channel-blocking AED use was inversely associated with diagnoses of colorectal cancer, lung cancer, gastric cancer, and hematological malignancies, with ASRs of 0.72 (95% CI: 0.60 - 0.86), 0.65 (0.51 - 0.81), 0.80 (0.65 - 0.98), and 0.50 (0.37 - 0.66), respectively. Positive associations between sodium channel-blocking AEDs and cancer were not found in the study.

CONCLUSION

Multi-methodological approaches using different methodologies, algorithms, and databases suggest that sodium channel-blocking AED use is inversely associated with colorectal cancer, lung cancer, gastric cancer, and hematological malignancies.

Favorable results after conservative management of 316 valproate intoxicated patients

Background:

Valproic acid (VPA) is an effective antiepileptic drug widely used worldwide. Despite several studies indicating the usefulness of intravenous L-carnitine in the treatment of VPA poisoning, this drug is not readily available in Iran. The aim of this study was to determine whether supportive care without antidote would result in acceptable outcomes in VPA poisoned patients.

Materials and Methods:

In an observational, retrospective, single-center case series, all patients >12-year-old with VPA overdose who had referred to a tertiary center between 2009 and 2013 were consecutively enrolled. Patients’ demographic and presenting features, physical examinations, clinical management, laboratory data, and outcomes were recorded.

Results:

A total of 316 patients were enrolled with pure VPA toxicity. The most common presenting signs/symptoms were drowsiness, nausea and vomiting, vertigo, and headache. In the course of the disease, 14 patients (4.4%) were intubated and three (0.9%) required hemodialysis with mean dialysis sessions of two. Fourteen patients were admitted to Intensive Care Unit, and seizures occurred in five. The initial level of consciousness was lower in patients with poor outcome. The median ingested dose of VPA in patients who required dialysis was significantly higher (20 vs. 6 g; P = 0.006). Multivariate analyses revealed that coma on presentation was associated with a worse outcome (P = 0.001; odds ratio = 61.5, 95% CI = 5.8-646.7).

Conclusion:

Prognosis of VPA poisoned patients appears to be good even with supportive care. According to our study, older age, ingestion of higher amounts of VPA and lower PCO₂, HCO₃, base excess, and CPK levels prone the patients to more severe toxicities in univariate analysis, but the main poor prognostic factor is coma on presentation in multivariate analysis.

Valproic acid stimulates proliferation of glial precursors during cortical gliogenesis in developing rat

Valproic acid (VPA) is a neurotherapeutic drug prescribed for seizures, bipolar disorder, and migraine, including women of reproductive age. VPA is a well-known teratogen that produces congenital malformations in many organs including the nervous system, as well as later neurodevelopmental disorders, including mental retardation and autism. In developing brain, few studies have examined VPA effects on glial cells, particularly astrocytes. To investigate effects on primary glial precursors, we developed new cell culture and in vivo models using frontal cerebral cortex of postnatal day (P2) rat. In vitro, VPA exposure elicited dose-dependent, biphasic effects on DNA synthesis and proliferation. In vivo VPA (300 mg/kg) exposure from P2 to P4 increased both DNA synthesis and cell proliferation, affecting primarily astrocyte precursors, as >75% of mitotic cells expressed brain lipid-binding protein. Significantly, the consequence of early VPA exposure was increased astrocytes, as both S100-β+ cells and glial fibrillary acidic protein were increased in adolescent brain. Molecularly, VPA served as an HDAC inhibitor in vitro and in vivo as enhanced proliferation was accompanied by increased histone acetylation, whereas it elicited changes in culture in cell-cycle regulators, including cyclin D1 and E, and cyclin-dependent kinase (CDK) inhibitors, p21 and p27. Collectively, these data suggest clinically relevant VPA exposures stimulate glial precursor proliferation, though at higher doses can elicit inhibition through differential regulation of CDK inhibitors. Because changes in glial cell functions are proposed as mechanisms contributing to neuropsychiatric disorders, these observations suggest that VPA teratogenic actions may be mediated through changes in astrocyte generation during development. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 780-798, 2016.

Strategy for enhancing the therapeutic efficacy of histone deacetylase inhibitor dacinostat: the novel paradigm to tackle monotonous cancer chemoresistance

Histone deacetylases (HDACs) regulate gene expression by creating the closed state of chromatin via histone hypoacetylation. Histone acetylation deregulation caused by aberrant expression of classical HDACs leads to imprecise gene regulation culminating in various diseases including cancer. Histone deacetylase inhibitors (HDACi), the small-molecules modulating the biological function of HDACs have shown promising results in inducing cell cycle arrest, differentiation and apoptosis in tumour models. HDACi do not show desired cytotoxic effect when used in monotherapy due to triggering of various resistance mechanisms in cancer cells emphasizing the desperate need of novel strategies that can be used to overcome such challenges. The present article provides intricate details about the novel HDACi dacinostat (LAQ-824) against multiple myeloma and acute myeloid leukaemia. The distinct molecular mechanisms modulated by dacinostat in exerting cytotoxic effect against the defined malignancies have also been detailed. The article also explains the strategy that can be used to circumvent the conventional therapy resistant cases and for enhancing the therapeutic efficacy of dacinostat for effective anticancer therapy.

Determination of valproic acid in human plasma using dispersive liquid-liquid microextraction followed by gas chromatography-flame ionization detection

OBJECTIVES

Dispersive liquid-liquid microextraction coupled with gas chromatography (GC)-flame ionization detector was developed for the determination of valproic acid (VPA) in human plasma.

MATERIALS AND METHODS

Using a syringe, a mixture of suitable extraction solvent (40 µl chloroform) and disperser (1 ml acetone) was quickly added to 10 ml of diluted plasma sample containing VPA (pH, 1.0; concentration of NaCl, 4% (w/v)), resulting in a cloudy solution. After centrifugation (6000 rpm for 6 min), an aliquot (1 µl) of the sedimented organic phase was removed using a 1-µl GC microsyringe and injected into the GC system for analysis. One variable at a time optimization method was used to study various parameters affecting the extraction efficiency of target analyte. Then, the developed method was fully validated for its accuracy, precision, recovery, stability, and robustness.

RESULTS

Under the optimum extraction conditions, good linearity range was obtained for the calibration graph, with correlation coefficient higher than 0.998. Limit of detection and lower limit of quantitation were 3.2 and 6 μg/ml, respectively. The relative standard deviations of intra and inter-day analysis of examined compound were less than 11.5%. The relative recoveries were found in the range of 97 to 107.5%. Finally, the validated method was successfully applied to the analysis of VPA in patient sample.

CONCLUSION

The presented method has acceptable levels of precision, accuracy and relative recovery and could be used for therapeutic drug monitoring of VPA in human plasma.

Valproic Acid Induces the Hyperacetylation of P53, Expression of P53 Target Genes, and Markers of the Intrinsic Apoptotic Pathway in Midorganogenesis Murine Limbs

In utero exposure to valproic acid (VPA), an anticonvulsant and histone deacetylase inhibitor (HDACi), increases the risk of congenital malformations. Although the mechanisms leading to the teratogenicity of VPA remain unsolved, several HDAC inhibitors increase cell death in cancer cell lines and embryonic tissues. Moreover, P53, the master regulator of apoptosis, is an established HDAC target. The purpose of this study was to investigate the effects of VPA on P53 signaling and markers of apoptosis during midorganogenesis in vitro limb development. Timed-pregnant CD1 mice (gestation day 12) were euthanized; embryonic forelimbs were excised and cultured in vitro for 3, 6, 12, or 24 hr in the presence or absence of VPA or valpromide (VPD), a non-HDACi analog of VPA. Quantitative RT-PCR and Western blots were used to assess the expression of candidate genes and proteins involved in P53 signaling and apoptosis. P53 hyperacetylation and a decrease (Survivin/Birc5 and Bcl2) or an increase (p21/Cdkn1a) in the expression of p53 target genes was observed only in VPA-exposed limbs. VPA exposure also triggered an increase in markers of apoptosis and DNA damage; the concentrations of cleaved caspase 9 and caspase 3, cleaved-poly (ADP-ribose) polymerase, and γ-H2AX were increased in VPA-exposed limbs. VPD treatment caused a small but significant increase in cleaved caspase 3. Thus, in vitro exposure to an HDACi such as VPA leads to P53 hyperacetylation, enhances the expression of P53 target genes, and triggers an increase in apoptosis that may contribute to teratogenicity.

Valproic acid enhances neuronal differentiation of sympathoadrenal progenitor cells

The antiepileptic drug valproic acid (VPA) has been shown to influence the neural differentiation and neurite outgrowth of neural stem cells. Sympathoadrenal progenitor cells share properties with neural stem cells and are considered a potential cell source in the treatment of neurodegenerative diseases. The present study therefore aims at modulating the neural differentiation potential of these cells by treatment with the histone deacetylase inhibitor VPA. We studied the epigenetic effects of VPA in two culture conditions: suspension conditions aimed to expand adrenomedullary sympathoadrenal progenitors within free-floating chromospheres and adherent cell cultures optimized to derive neurons. Treatment of chromospheres with VPA may launch neuronal differentiation mechanisms and improve their neurogenic potential upon transplantation. However, also transplantation of differentiated functional neurons could be beneficial. Treating chromospheres for 7 days with clinically relevant concentrations of VPA (2 mm) revealed a decrease of neural progenitor markers Nestin, Notch2 and Sox10. Furthermore, VPA initiated catecholaminergic neuronal differentiation indicated by upregulation of the neuronal marker β-III-tubulin, the dopaminergic transcription factor Pitx3 and the catecholaminergic enzymes TH and GTPCH. In adherent neural differentiation conditions, VPA treatment improved the differentiation of sympathoadrenal progenitor cells into catecholaminergic neurons with significantly elevated levels of nor- and epinephrine. In conclusion, similar to neural stem cells, VPA launches differentiation mechanisms in sympathoadrenal progenitor cells that result in increased generation of functional neurons. Thus, data from this study will be relevant to the potential use of chromaffin progenitors in transplantation therapies of neurodegenerative diseases.

Interaction between carbenoxolone and valproic acid on pentylenetetrazole kindling model of epilepsy

Gap junctions play an important role in the synchronized neuronal discharges. The main reason of the epileptic seizures is disruption of this synchronization. Therefore, the aim of the present study is to explore the combination valproic acid with carbenoxolone in pentylenetetrazole-kindled rats. In the first set of experiments, pentylenetetrazole (35 mg/kg intraperitoneally was administered to the rats to produce the kindling and then permanent screw electrodes to record electroencephalographic signals. The kindled rats were divided into six groups. While electroencephalographic recordings received from animals, behavioral evaluation was done by an observer. The data analysis was performed using T test and Mann-Whitney U tests. The dose of 40 mg/kg carbenoxolone was the most effective in carbenoxolone treatment groups. It prevented generalized seizures by 50%, reduced seizure stage, seizure duration and spike frequency. There was no significant difference between carbenoxolone-valproic acid combination and valproic acid on any seizure parameters. The current study is the first study which shows the interaction of carbenoxolone with valproic acid in pentylenetetrazole kindling model. As a result, carbenoxolone-valproic acid combination was not more effective than the standalone use of these drugs.

Valproic Acid Arrests Proliferation but Promotes Neuronal Differentiation of Adult Spinal NSPCs from SCI Rats

Although the adult spinal cord contains a population of multipotent neural stem/precursor cells (NSPCs) exhibiting the potential to replace neurons, endogenous neurogenesis is very limited after spinal cord injury (SCI) because the activated NSPCs primarily differentiate into astrocytes rather than neurons. Valproic acid (VPA), a histone deacetylase inhibitor, exerts multiple pharmacological effects including fate regulation of stem cells. In this study, we cultured adult spinal NSPCs from chronic compressive SCI rats and treated with VPA. In spite of inhibiting the proliferation and arresting in the G0/G1 phase of NSPCs, VPA markedly promoted neuronal differentiation (β-tubulin III(+) cells) as well as decreased astrocytic differentiation (GFAP(+) cells). Cell cycle regulator p21(Cip/WAF1) and proneural genes Ngn2 and NeuroD1 were increased in the two processes respectively. In vivo, to minimize the possible inhibitory effects of VPA to the proliferation of NSPCs as well as avoid other neuroprotections of VPA in acute phase of SCI, we carried out a delayed intraperitoneal injection of VPA (150 mg/kg/12 h) to SCI rats from day 15 to day 22 after injury. Both of the newborn neuron marker doublecortin and the mature neuron marker neuron-specific nuclear protein were significantly enhanced after VPA treatment in the epicenter and adjacent segments of the injured spinal cord. Although the impaired corticospinal tracks had not significantly improved, Basso-Beattie-Bresnahan scores in VPA treatment group were better than control. Our study provide the first evidence that administration of VPA enhances the neurogenic potential of NSPCs after SCI and reveal the therapeutic value of delayed treatment of VPA to SCI.

Valproate-induced liver injury: modulation by the omega-3 fatty acid DHA proposes a novel anticonvulsant regimen

Background

The polyunsaturated, ω-3 fatty acid, docosahexaenoic acid (DHA), claims diverse cytoprotective potentials, although via largely undefined triggers. Thus, we currently first tested the ability of DHA to ameliorate valproate (VPA)-evoked hepatotoxicity, to modulate its anticonvulsant effects, then sought the cellular and molecular basis of such actions. Lastly, we also verified whether DHA may kinetically alter plasma levels/clearance rate of VPA.

Methods and Results

VPA (500 mg/kg orally for 14 days in rats) evoked prominent hepatotoxicity that appeared as a marked rise (2- to 4-fold) in serum hepatic enzymes (γ-glutamyl transferase [γ-GT], alanine aminotransferase [ALT], and alkaline phosphatase [ALP]), increased hepatic lipid peroxide (LPO) and tumor necrosis factor-alpha (TNFα) levels, as well as myeloperoxidase (MPO) activity (3- to 5-fold), lowering of serum albumin (40 %), and depletion of liver reduced-glutathione (GSH, 35 %). Likewise, histopathologic examination revealed hepatocellular degeneration, replacement by inflammatory cells, focal pericentral necrosis, and micro/macrovesicular steatosis. Concurrent treatment with DHA (250 mg/kg) markedly blunted the elevated levels of liver enzymes, lipid peroxides, TNFα, and MPO activity, while raising serum albumin and hepatic GSH levels. DHA also alleviated most of the cytologic insults linked to VPA. Besides, in a pentylenetetrazole (PTZ) mouse convulsion model, DHA (250 mg/kg) markedly increased the latency in convulsion evoked by VPA, beyond their individual responses. Lastly, pharmacokinetic studies revealed that joint DHA administration did not alter serum VPA concentrations.

Conclusions

DHA substantially ameliorated liver injury induced by VPA, while also markedly boosted its pharmacologic effects. DHA manipulated definite cellular machinery to curb liver oxidative stress and inflammation, without affecting VPA plasma levels. Collectively, these protective and synergy profiles for DHA propose a superior VPA-drug combination regimen.

Valproic Acid Neuroprotection in the 6-OHDA Model of Parkinson's Disease Is Possibly Related to Its Anti-Inflammatory and HDAC Inhibitory Properties

Parkinson's disease is a neurodegenerative disorder where the main hallmark is the dopaminergic neuronal loss. Besides motor symptoms, PD also causes cognitive decline. Although current therapies focus on the restoration of dopamine levels in the striatum, prevention or disease-modifying therapies are urgently needed. Valproic acid (VA) is a wide spectrum antiepileptic drug, exerting many biochemical and physiological effects. It has been shown to inhibit histone deacetylase which seems to be associated with the drug neuroprotective action. The objectives were to study the neuroprotective properties of VA in a model of Parkinson's disease, consisting in the unilateral striatal injection of the neurotoxin 6-OHDA. For that, male Wistar rats (250 g) were divided into the groups: sham-operated (SO), untreated 6-OHDA-lesioned, and 6-OHDA-lesioned treated with VA (25 or 50 mg/kg). Oral treatments started 24 h after the stereotaxic surgery and continued daily for 2 weeks, when the animals were subjected to behavioral evaluations (apomorphine-induced rotations and open-field tests). Then, they were sacrificed and had their mesencephalon, striatum, and hippocampus dissected for neurochemical (DA and DOPAC determinations), histological (Fluoro-Jade staining), and immunohistochemistry evaluations (TH, OX-42, GFAP, TNF-alpha, and HDAC). The results showed that VA partly reversed behavioral and neurochemical alterations observed in the untreated 6-OHDA-lesioned rats. Besides, VA also decreased neuron degeneration in the striatum and reversed the TH depletion observed in the mesencephalon of the untreated 6-OHDA groups. This neurotoxin increased the OX-42 and GFAP immunoreactivities in the mesencephalon, indicating increased microglia and astrocyte reactivities, respectively, which were reversed by VA. In addition, the immunostainings for TNF-alpha and HDAC demonstrated in the untreated 6-OHDA-lesioned rats were also decreased after VA treatments. These results were observed not only in the CA1 and CA3 subfields of the hippocampus, but also in the temporal cortex. In conclusion, we showed that VA partly reversed the behavioral, neurochemical, histological, and immunohistochemical alterations observed in the untreated 6-OHDA-lesioned animals. These effects are probably related to the drug anti-inflammatory activity and strongly suggest that VA is a potential candidate to be included in translational studies for the treatment of neurodegenerative diseases as PD.

Changes in the anti-oxidant system in adult epilepsy patients receiving anti-epileptic drugs

Anti-epileptic drugs (AEDs) have been widely used in patients with epilepsy. This study evaluated the adverse effects of two commonly prescribed AED monotherapies, carbamazepine (CBZ) and valproic acid (VPA). The aim of this study was to evaluate the influence of these anti-epileptic drugs on paraoxonase-1 (PON-1), glutathione S-transferase (GST) and acetyl cholinesterase (AChE) activities in the serum of adult patients with epilepsy. Of the 56 epileptic adults, 28 were given valproate, and the remaining 28 were given carbamazepine. Glutathione (GSH) levels in epilepsy patients receiving anti-epileptic drug treatment were insignificantly higher compared with controls. GST activity in epilepsy patients receiving anti-epileptic drug treatment was insignificantly lower compared with controls. PON1 and AChE activity in epilepsy patients receiving anti-epileptic drug treatment was significantly lower compared with controls. PON1 and AChE activities in the serum of patients treated with carbamazepine monotherapy were lower than in patients treated with valproic acid monotherapy.

Epigenetic regulation of persistent pain

Persistent or chronic pain is tightly associated with various environmental changes and linked to abnormal gene expression within cells processing nociceptive signaling. Epigenetic regulation governs gene expression in response to environmental cues. Recent animal model and clinical studies indicate that epigenetic regulation plays an important role in the development or maintenance of persistent pain and possibly the transition of acute pain to chronic pain, thus shedding light in a direction for development of new therapeutics for persistent pain.

Perinatal Influences of Valproate on Brain and Behaviour: An Animal Model for Autism

Valproic acid or valproate (VPA) is an anti-convulsant and mood stabiliser effective in treating epilepsy and bipolar disorders. Although in adults VPA is well tolerated and safe, there is convincing evidence that it has teratogenic properties, ranging from mild neurodevelopmental changes to severe congenital malformations. In particular, studies involving humans and other animals have shown that prenatal exposure to VPA can induce developmental abnormalities reminiscent of autism spectrum disorder (ASD). In this chapter, we discuss the connection between VPA and ASD, evaluate the VPA animal model of ASD, and describe the possible molecular mechanisms underlying VPA's teratogenic properties.

Acute administration of lithium, but not valproate, modulates cognitive judgment bias in rats

RATIONALE AND OBJECTIVES

Both valproic acid (VPA) and lithium (LI) are well-established treatments for therapy of intense and sustained mood shifts, which are characteristics of affective disorders, such as bipolar disorder (BP). As mood and cognitive judgment bias have been found to be strongly interrelated, the present study investigated, in an animal model, whether acute treatment with VPA or LI could affect cognitive judgment bias.

METHODS

To accomplish this goal, two groups of rats received single injections of either VPA or LI after initial behavioral training and were subsequently tested with the ambiguous-cue interpretation (ACI) test. Both drugs were administered in three doses using the fully randomized Latin square design.

RESULTS

VPA (100, 200, and 400 mg/kg) had no significant effect on the interpretation of the ambiguous cue. LI at the lowest dose (10 mg/kg) had no effect; at an intermediate dose (50 mg/kg), it significantly biased animals towards positive interpretation of the ambiguous cue, and at the highest dose (100 mg/kg), it impaired the ability of animals to complete the test.

CONCLUSION

To our knowledge, this is the first study demonstrating lithium's effects on increased optimistic judgment bias. Future studies may focus on the ability of putative pharmacotherapies to modify the cognitive judgment bias dimension of patients at risk for bipolar disorder or depression.

Effects of histone deacetylase inhibitor valproic acid on skeletal myocyte development

The tight interaction between genomic DNA and histones, which normally represses gene transcription, can be relaxed by histone acetylation. This loosening of the DNA-histone complex is important for selective gene activation during stem cell differentiation. Histone acetylation may be increased through the application of histone deacetylase inhibitors at the early stages of differentiation to modulate lineage commitment. We examined the effects of the histone deacetylase inhibitor valproic acid on the differentiation of pluripotent stem cells into skeletal myocytes. Our data demonstrated that valproic acid can act in concert with retinoic acid to enhance the commitment of stem cells into the skeletal myocyte lineage reinforcing the notion that histone acetylation is important for skeletal myogenesis. Thus, using a combination of small molecules to exploit different signaling pathways pertaining to specific gene programs will allow for modulation of lineage specification and stem cell differentiation in potential cell-based therapies.

Sudden cardiac death is associated both with epilepsy and with use of antiepileptic medications

OBJECTIVE

Epilepsy is associated with increased risk for sudden cardiac death (SCD). We aimed to establish, in a community based study, whether this association is mediated by epilepsy per se, use of antiepileptic medications (AEMs), or both.

METHODS

We studied SCD cases and age/sex matched controls in a case-control study in a large scale general practitioners' research database (n=478 661 patients). SCD risk for symptomatic epilepsy (seizure <2 years before SCD), stable epilepsy (no seizure <2 years before SCD), and use of AEMs (any indication) was determined.

RESULTS

We identified 926 SCD cases and 9832 controls. Fourteen cases had epilepsy. Epilepsy was associated with an increased SCD risk (cases 1.5%, controls 0.5%; adjusted OR 2.8, 95% CI 1.4 to 5.3). SCD risk was increased for symptomatic epilepsy (cases 0.9%, controls 0.1%; adjusted OR 5.8, 95% CI 2.1 to 15.6), but not with stable epilepsy (cases 0.6%, controls 0.4%; adjusted OR 1.6, 95% CI 0.7 to 4.1). AEM use was found in 23 cases and was associated with an increased SCD risk (cases 2.5%, controls 0.8%; adjusted OR overall 2.6, 95% CI 1.5 to 4.3) among symptomatic epilepsy cases (cases 0.9%, controls 0.1%; adjusted OR 6.4, 95% CI 2.4 to 17.4) and non-epilepsy cases (cases 1.0%, controls 0.4%; adjusted OR 2.3, 95% CI 1.01 to 5.2). Increased SCD risk was associated with sodium channel blocking AEMs (cases 1.6%, controls 0.4%; adjusted OR 2.8, 95% CI 1.1 to 7.2), but not with non-sodium channel blocking AEMs. Carbamazepine and gabapentin were associated with increased SCD risk (carbamazepine: cases 1.1%, controls 0.3%; adjusted OR 3.2, 95% CI 1.1 to 9.2; gabapentin: cases 0.3%, controls 0.1%; adjusted OR 5.7, 95% CI 1.2 to 27.9).

CONCLUSIONS

Epilepsy and AEM use are both associated with increased SCD risk in the general population. Poor seizure control contributes to increased SCD risk in epilepsy, while sodium channel blockade contributes to SCD susceptibility in AEM users.

HDAC inhibition through valproic acid modulates the methylation profiles in human embryonic kidney cells

Post-translational modifications on the tails of core and linker histones dictate transcription and have vital roles in disease and development. Acetylation and deacetylation events enabled by histone acetyl transferases and histone deacetylases (HDACs) on the chromatin milieu are intricately involved in gene regulation. Inhibition of HDACs is emerging as a powerful strategy in regenerative therapy, transplantation, development and in nuclear reprogramming events. Valproic acid (VPA), belonging to the short-chain fatty acid group of HDAC inhibitors, modulates the epigenome altering gene expression profiles across cell lines. This work attempts to explore the methylation profiles triggered by VPA treatment on human embryonic kidney cells (HEK 293) through a biochemical and computational approach. VPA treatment (for 48 h) has been observed to hypermethylate lysine 4 on the core histone H3 and confers a hypomethylation status of H3 lysine 27 in HEK 293 cells leaving the nuclear area and nuclear contour unaltered. Our structural docking and Binding Free Energy (BFE) calculations establish an active role for VPA in inhibiting the demethylase JARID1A (Jumonji, AT Rich Interactive Domain 1A) and the methyl-transferase EZH2 (Enhancer of Zeste Homologue 2). This work has also proven that VPA can inhibit the activity of proteins like GSK3β and PKCβII involved in developmental disorders. This work establishes a dynamic correlation between histone methylation events and HDAC inhibition and may define newer epigenetic strategies for treating neurodevelopmental and oncological disorders.

Structural and energetic analysis to provide insight residues of CYP2C9, 2C11 and 2E1 involved in valproic acid dehydrogenation selectivity

Docking and molecular dynamics (MD) simulation have been two computational techniques used to gain insight about the substrate orientation within protein active sites, allowing to identify potential residues involved in the binding and catalytic mechanisms. In this study, both methods were combined to predict the regioselectivity in the binding mode of valproic acid (VPA) on three cytochrome P-450 (CYP) isoforms CYP2C9, CYP2C11, and CYP2E1, which are involved in the biotransformation of VPA yielding reactive hepatotoxic intermediate 2-n-propyl-4-pentenoic acid (4nVPA). There are experimental data about hydrogen atom abstraction of the C4-position of VPA to yield 4nVPA, however, there are not structural evidence about the binding mode of VPA and 4nVPA on CYPs. Therefore, the complexes between these CYP isoforms and VPA or 4nVPA were studied to explore their differences in binding and energetic stabilization. Docking results showed that VPA and 4nVPA are coupled into CYPs binding site in a similar conformation, but it does not explain the VPA hydrogen atom abstraction. On the other hand, MD simulations showed a set of energetic states that reorient VPA at the first ns, then making it susceptible to a dehydrogenation reaction. For 4nVPA, multiple binding modes were observed in which the different states could favor either undergo other reaction mechanism or ligand expulsion from the binding site. Otherwise, the energetic and entropic contribution point out a similar behavior for the three CYP complexes, showing as expected a more energetically favorable binding free energy for the complexes between CYPs and VPA than with 4nVPA.

Administration of histone deacetylase inhibitor during neonatal period changes emotionality of adult male 129Sv mice

Environmental factors acting during the neonatal period affected the formation of phenotype of adult animals via epigenetic modifications of the genome, e.g. histone acetylation. We studied the effects of blockage of histone deacetylases with sodium valproate on week 1 of life on the behavioral pattern of adult male 129Sv mice. The results of behavioral tests attest to long-term changes in emotional, but not cognitive pattern of adult animals after sodium valproate administration, which manifested in increased anxiety of animals.

The role of the entorhinal cortex in epileptiform activities of the hippocampus

BACKGROUND

Temporal lobe epilepsy (TLE) is the commonest type of epilepsy in adults, and the hippocampus is indicated to have a close relationship with TLE. Recent researches also indicate that the entorhinal cortex (EC) is involved in epilepsy. To explore the essential role that the EC may play in epilepsy, a computational model of the hippocampal CA3 region was built, which consisted of pyramidal cells and two types of interneurons. By changing the input signals from the EC, the effects of EC on epileptiform activities of the hippocampus were investigated. Additionally, recent studies have found that the antiepileptic drug valproate (VPA) can block ictal discharges but cannot block interictal discharges in vitro, and the mechanism under this phenomenon is still confusing. In our model, the effects of VPA on epileptiform activities were simulated and some mechanisms were explored.

RESULTS

Interictal discharges were induced in the model without the input signals from the EC, whereas the model with the EC input produced ictal discharges when the EC input contained ictal discharges. The GABA-ergic connection strength was enhanced and the NMDA-ergic connection strength was reduced to simulate the effects of VPA, and the simulation results showed that the disappearance of ictal discharges in the model mainly due to the disappearance of ictal discharges in the input signals from the EC.

CONCLUSIONS

Simulation results showed that ictal discharges in the EC were necessary for the hippocampus to generate ictal discharges, and VPA might block the ictal discharges in the EC, which led to the disappearance of ictal discharges in the hippocampus.

Activation of GATA4 gene expression at the early stage of cardiac specification

Currently, there are no effective treatments to directly repair damaged heart tissue after cardiac injury since existing therapies focus on rescuing or preserving reversibly damaged tissue. Cell-based therapies using cardiomyocytes generated from stem cells present a promising therapeutic approach to directly replace damaged myocardium with new healthy tissue. However, the molecular mechanisms underlying the commitment of stem cells into cardiomyocytes are not fully understood and will be critical to guide this new technology into the clinic. Since GATA4 is a critical regulator of cardiac differentiation, we examined the molecular basis underlying the early activation of GATA4 gene expression during cardiac differentiation of pluripotent stem cells. Our studies demonstrate the direct involvement of histone acetylation and transcriptional coactivator p300 in the regulation of GATA4 gene expression. More importantly, we show that histone acetyltransferase (HAT) activity is important for GATA4 gene expression with the use of curcumin, a HAT inhibitor. In addition, the widely used histone deacetylase inhibitor valproic acid enhances both histone acetylation and cardiac specification.

Phase I study of anti-VEGF monoclonal antibody bevacizumab and histone deacetylase inhibitor valproic acid in patients with advanced cancers

PURPOSE

Anti-angiogenic agents combined with histone deacetylase inhibitors act synergistically in vitro and in vivo. We conducted a phase I study of the combination of the anti-VEGF monoclonal antibody bevacizumab and histone deacetylase inhibitor valproic acid in patients with advanced cancers.

METHODS

Bevacizumab was administered at escalating dosages of 2.5-11 mg/kg on days 1 and 15, and oral valproic acid at dosages of 5.3-10 mg/kg on days 1-28 every 28 days to determine the maximum tolerated dose. Pharmacodynamic parameters were assessed in peripheral blood mononuclear cells (histone H3 acetylation) and serum (valproic acid levels).

RESULTS

Fifty-seven patients were enrolled. Dose-limiting toxicities were grade 3 altered mental status (n = 2), related to valproic acid. Bevacizumab 11 mg/kg given on days 1 and 15 and valproic acid 5.3 mg/kg daily were the recommended phase II dosages. Stable disease (SD) ≥6 months was reported in 4/57 (7 %) of patients, including two patients with colorectal cancer who had progressed previously on bevacizumab. Of the 39 patients evaluated for histone acetylation, 2 of 3 (67 %) patients with SD ≥6 months showed histone acetylation, while 8 of 36 (22 %) without SD ≥6 months demonstrated histone acetylation (p = 0.16). Patients with any grade of hypertension, compared to others, had a prolonged median survival (11.1 vs. 5.8 months; p = 0.012).

CONCLUSIONS

The combination of bevacizumab 11 mg/kg and valproic acid 5.3 mg/kg is safe in patients with advanced malignancies, with activity in colorectal, gastroesophageal junction, and prostate cancer. Patients with hypertension had improved overall survival.

Novel Vitamin K analogs suppress seizures in zebrafish and mouse models of epilepsy

Epilepsy is a debilitating disease affecting 1-2% of the world's population. Despite this high prevalence, 30% of patients suffering from epilepsy are not successfully managed by current medication suggesting a critical need for new anti-epileptic drugs (AEDs). In an effort to discover new therapeutics for the management of epilepsy, we began our study by screening drugs that, like some currently used AEDs, inhibit histone deacetylases (HDACs) using a well-established larval zebrafish model. In this model, 7-day post fertilization (dpf) larvae are treated with the widely used seizure-inducing compound pentylenetetrazol (PTZ) which stimulates a rapid increase in swimming behavior previously determined to be a measurable manifestation of seizures. In our first screen, we tested a number of different HDAC inhibitors and found that one, 2-benzamido-1 4-naphthoquinone (NQN1), significantly decreased swim activity to levels equal to that of valproic acid, 2-n-propylpentanoic acid (VPA). We continued to screen structurally related compounds including Vitamin K3 (VK3) and a number of novel Vitamin K (VK) analogs. We found that VK3 was a robust inhibitor of the PTZ-induced swim activity, as were several of our novel compounds. Three of these compounds were subsequently tested on mouse seizure models at the National Institute of Neurological Disorders and Stroke (NINDS) Anticonvulsant Screening Program. Compound 2h reduced seizures particularly well in the minimal clonic seizure (6Hz) and corneal-kindled mouse models of epilepsy, with no observable toxicity. As VK3 affects mitochondrial function, we tested the effects of our compounds on mitochondrial respiration and ATP production in a mouse hippocampal cell line. We demonstrate that these compounds affect ATP metabolism and increase total cellular ATP. Our data indicate the potential utility of these and other VK analogs for the prevention of seizures and suggest the potential mechanism for this protection may lie in the ability of these compounds to affect energy production.

Valproic acid, but not levetiracetam, selectively decreases HDAC7 and HDAC2 expression in human ovarian cancer cells

Histone deacetylases (HDACs) are often overexpressed in cancer cells, leading to altered expression and activity of numerous proteins involved in carcinogenesis. Recent evidence suggests that expression of class I HDACs is increased in ovarian carcinomas and plays a significant role in carcinogenesis and resistance to chemotherapeutic agents. Two compounds, valproic acid (VPA) and levetiracetam (LEV), exhibit HDAC inhibitor (HDACI) activity in various cell types, but data concerning their activity in ovarian cancer are lacking. Here we compared the effects of VPA and LEV as HDACIs, using a human ovarian cancer cell line, OVCAR-3. Cells were cultured with VPA or LEV at concentrations between 1 and 10 mM for 1-24h. HDAC activity was determined by fluorometric assay and confirmed by western blotting. Expression of HDAC genes was determined by real-time PCR and HDAC proteins expression was evaluated by western blotting. Additionally, we used high-performance liquid chromatography to determine whether OVCAR-3 cells can metabolize LEV to its major metabolite, 2-pyrrolidinone-n-butyric acid (PBA), which might exert HDACI activity. LEV, however, had no apparent effect on HDAC activity, or gene and protein expression. The OVCAR-3 cell line was able to metabolize LEV to PBA, but the effect was small. Our observations suggest that VPA should be considered as a possible adjunctive drug in ovarian cancer treatment.

Effects of valproate sodium on extracellular signal-regulated kinase 1/2 phosphorylation following hippocampal neuronal epileptiform discharge in rats

The aim of the present study was to investigate the effects of valproate sodium (VPAS) on the phosphorylation extracellular signal-regulated kinase 1/2 (ERK1/2) following hippocampal neuronal epileptiform discharge in rat neurons. The study used neurons from female and male neonate Sprague-Dawley (SD) rats (at least 24 h old), which were rapidly decapitated. Following the successful development of the epileptiform discharge cell model, the neurons were divided into two groups, the VPAS group and the control group. In the concentration-response experiment, the neurons were incubated with three different concentrations of VPAS (50, 75 and 100 mg/l) 30 min prior to the epileptiform discharge. The expression of phosphorylated ERK1/2 (p-ERK1/2) was examined using an immunofluorescence technique. In the time-response experiment, the neurons were incubated with VPAS (50 mg/l) and monitored at different time-points (30 min prior to the epileptiform discharge and 0 min, 30 min, 2 h and 6 h subsequent to epileptiform discharge), and western blotting was employed to measure the changes in p-ERK1/2 protein expression. No significant differences in the expression of p-ERK1/2 among the neurons treated with different concentrations of VPAS were identified in the concentration-response experiment. However, in the time-response experiment, the expression of p-ERK1/2 30 min prior to the epileptiform discharge was significantly lower compared with that at the other time-points. Furthermore, 50 mg/l VPAS was capable of decreasing the action potential frequency of the neuronal epileptiform discharge. ERK1/2 was excessively and persistently activated following the epileptiform discharge of the neurons. In addition, a low concentration of VPAS was effective at inhibiting the phosphorylation of ERK1/2 at an earlier period of neuronal epileptiform discharge.

Evaluation of neurotoxic and neuroprotective pathways affected by antiepileptic drugs in cultured hippocampal neurons

In this study we evaluated the neurotoxicity of eslicarbazepine acetate (ESL), and of its in vivo metabolites eslicarbazepine (S-Lic) and R-licarbazepine (R-Lic), as compared to the structurally-related compounds carbamazepine (CBZ) and oxcarbazepine (OXC), in an in vitro model of cultured rat hippocampal neurons. The non-related antiepileptic drugs (AEDs) lamotrigine (LTG) and sodium valproate (VPA) were also studied. We assessed whether AEDs modulate pro-survival/pro-apoptotic pathways, such as extracellular-regulated kinase (ERK1/2), Akt and stress activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK). We found that neither ESL nor its metabolites, CBZ or LTG, up to 0.3mM, for 24h of exposure, decreased cell viability. OXC was the most toxic drug decreasing cell viability in a concentration-dependent manner, leading to activation of caspase-3 and PARP cleavage. VPA caused the appearance of the apoptotic markers, but did not alter cell viability. ESL, S-Lic and OXC decreased the levels of phospho-ERK1/2 and of phospho-Akt, when compared to basal levels, whereas CBZ decreased phospho-SAPK/JNK and phospho-Akt levels. LTG and VPA increased the phosphorylation levels of SAPK/JNK. These results suggest that ESL and its main metabolite S-Lic, as well as CBZ, LTG and VPA, are less toxic to hippocampal neurons than OXC, which was the most toxic agent.