Oxidative Stress as a Mechanism of Valproic Acid-Associated Hepatotoxicity

A trend over time study of hepatic Farnesoid-X-activated receptor and its downstream targets modulation by valproic acid in mice

Valproic acid (VA) is a broad-spectrum anticonvulsant agent that acts through several molecular mechanisms to control different types of seizures. The main concern of the drug is its liver toxicity. Considering the regulatory roles of the Farnesoid nuclear receptors and the nuclear transcription factor Nrf2 in modifying and neutralizing the harmful effects of oxidative damage, the present study was designed to evaluate the role of FXR-Nrf2 and some downstream target gene alterations in hepatotoxicity induced by VA. Thirty-five eight-week-old male albino mice were randomly divided into five groups, including a control group, and four groups were assigned to receive VA (300 mg/kg/day; oral) for 3, 7, 10, and 14 days. Serum levels of ALT, AST, ALP, and total and direct bilirubin (TB, DB) were measured. Liver histology and the expression of FXR, Nrf2, α-GST, SOD, and TNF-α were assessed using H&E staining and real-time RT-PCR techniques. Maximum extent of biochemical and histopathological damage was observed on the 14th day, but changes in the expression of FXR, Nrf2, α-GST, and SOD were seen at three points: a significant upregulation on the 3rd day, a remarkable downregulation on the 10th day, and a second-time upregulation on the 14th day. In conclusion, considering the observed dysregulation in FXR-Nrf2 cascade expression during VA administration, it seems that downregulation in this pathway and consequently its downstream detoxification and antioxidant genes may play a role in liver toxicity.

Ferroptosis promotes valproate-induced liver steatosis in vitro and in vivo

Valproic acid (VPA), a common antiepileptic drug, can cause liver steatosis after long-term therapy. However, an impact of ferroptosis on VPA-induced liver steatosis has not been investigated. In the study, treatment with VPA promoted ferroptosis in the livers of mice by elevating ferrous iron (Fe2+) levels derived from the increased absorption by transferrin receptor 1 (TFR1) and the decreased storage by ferritin (FTH1 and FTL), disrupting the redox balance via reduced levels of solute carrier family 7 member 11 (SLC7A11), glutathione (GSH), and glutathione peroxidase 4 (GPX4), and augmenting acyl-CoA synthetase long-chain family member 4 (ACSL4) -mediated lipid peroxide generation, accompanied by enhanced liver steatosis. All the changes were significantly reversed by co-treatment with an iron-chelating agent, deferoxamine mesylate (DFO) and a ferroptosis inhibitor, ferrostatin-1 (Fer-1). Similarly, the increases in Fe2+, TFR1, and ACSL4 levels, as well as the decreases in GSH, GPX4, and ferroportin (FPN) levels, were detected in VPA-treated HepG2 cells. These changes were also attenuated after co-treatment with Fer-1. It demonstrates that ferroptosis promotes VPA-induced liver steatosis through iron overload, inhibition of the GSH-GPX4 axis, and upregulation of ACSL4. It offers a potential therapy targeting ferroptosis for patients with liver steatosis following VPA treatment.

Valproic Acid Causes Redox-Regulated Post-Translational Protein Modifications That Are Dependent upon P19 Cellular Differentiation States

Valproic acid (VPA) is a common anti-epileptic drug and known neurodevelopmental toxicant. Although the exact mechanism of VPA toxicity remains unknown, recent findings show that VPA disrupts redox signaling in undifferentiated cells but has little effect on fully differentiated neurons. Redox imbalances often alter oxidative post-translational protein modifications and could affect embryogenesis if developmentally critical proteins are targeted. We hypothesize that VPA causes redox-sensitive post-translational protein modifications that are dependent upon cellular differentiation states. Undifferentiated P19 cells and P19-derived neurons were treated with VPA alone or pretreated with D3T, an inducer of the nuclear factor erythroid 2-related factor 2 (NRF2) antioxidant pathway, prior to VPA exposure. Undifferentiated cells treated with VPA alone exhibited an oxidized glutathione redox couple and increased overall protein oxidation, whereas differentiated neurons were protected from protein oxidation via increased S-glutathionylation. Pretreatment with D3T prevented the effects of VPA exposure in undifferentiated cells. Taken together, our findings support redox-sensitive post-translational protein alterations in undifferentiated cells as a mechanism of VPA-induced developmental toxicity and propose NRF2 activation as a means to preserve proper neurogenesis.

Associations between one-carbon metabolism and valproic acid-induced liver dysfunction in epileptic patients

Valproic acid (VPA) has been widely used as an antiepileptic drug for decades. Although VPA is effective and well-tolerated, long-term VPA treatment is usually associated with hepatotoxicity. However, the underlying mechanisms of VPA-caused hepatotoxicity remain unclear. In this study, a total of 157 pediatric patients with epilepsy were recruited and divided into normal liver function (NLF, 112 subjects) group and abnormal liver function (ABLF, 45 subjects) group. We observed that MTHFR A1298C and MTHFR C677T variants may be linked to VPA-induced liver dysfunction (p = 0.001; p = 0.023, respectively). We also found that the MTHFR A1298C polymorphism was associated with a higher serum Hcy level (p = 0.001) and a lower FA level (p = 0.001). Moreover, the serum Hcy levels was strongly correlated with the GSH and TBARS concentrations (r = -0.6065, P < 0.001; r = 0.6564, P < 0.001, respectively). Furthermore, logistic analysis indicated that MTHFR A1298C/C677T polymorphisms and increased Hcy concentrations may be risk factors for VPA-induced liver dysfunction. These results suggested that individual susceptibility to VPA-induced liver dysfunction may result from MTHFR A1298C/C677T polymorphisms and increased Hcy levels. This study may be helpful for the prevention and guidance of VPA-induced liver dysfunction.

Chitosan Nanoparticles Loaded with Quercetin and Valproic Acid: A Novel Approach for Enhancing Antioxidant Activity against Oxidative Stress in the SH-SY5Y Human Neuroblastoma Cell Line

BACKGROUND

Multiple drug-delivery systems obtained by loading nanoparticles (NPs) with different drugs that have different physicochemical properties present a promising strategy to achieve synergistic effects between drugs or overcome undesired effects. This study aims to develop a new NP by loading quercetin (Que) and valproic acid (VPA) into chitosan. In this context, our study investigated the antioxidant activities of chitosan NPs loaded with single and dual drugs containing Que against oxidative stress.

METHOD

The synthesis of chitosan NPs loaded with a single (Que or VPA) and dual drug (Que and VPA), the characterization of the NPs, the conducting of in vitro antioxidant activity studies, and the analysis of the cytotoxicity and antioxidant activity of the NPs in human neuroblastoma SH-SY5Y cell lines were performed.

RESULT

The NP applications that protected cell viability to the greatest extent against H2O2-induced cell damage were, in order, 96 µg/mL of Que-loaded chitosan NP (77.30%, 48 h), 2 µg/mL of VPA-loaded chitosan NP (70.06%, 24 h), 96 µg/mL of blank chitosan NP (68.31%, 48 h), and 2 µg/mL of Que- and VPA-loaded chitosan NP (66.03%, 24 h).

CONCLUSION

Our study establishes a successful paradigm for developing drug-loaded NPs with a uniform and homogeneous distribution of drugs into NPs. Chitosan NPs loaded with both single and dual drugs possessing antioxidant activity were successfully developed. The capability of chitosan NPs developed at the nanometer scale to sustain cell viability in SH-SY5Y cell lines implies the potential of intranasal administration of chitosan NPs for future studies, offering protective effects in central nervous system diseases.

The implication of LPS/TLR4 and FXR receptors in hepatoprotective efficacy of indole-3-acetic acid and chenodeoxycholic acid

AIM

Valproic acid (VPA) belongs to the first-generation antiepileptic drugs, yet its prolonged use can cause life-threatening liver damage. The importance of our study is to investigate the protective effect of indole-3-acetic acid (IAA), chenodeoxycholic acid (CDCA) and their combination on VPA-induced liver injury focusing on lipopolysaccharides (LPS)/toll-like receptor 4 (TLR4) pathway and farnesoid X receptor (FXR).

METHODS

Thirty rats were randomly assigned into five groups, normal control group, VPA group received 500 mg/kg of VPA intraperitoneally. The remaining groups were orally treated with either 40 mg/kg of IAA, 90 mg/kg of CDCA, or a combination of both, along with VPA. All treatments were administered one hour after the administration of VPA for three weeks.

KEY FINDINGS

VPA group showed significant elevations in the liver weight/body weight ratio, serum aminotransferases, triglyceride, and total cholesterol levels. Hepatic glutathione (GSH) level and superoxide dismutase (SOD) activity were significantly decreased, while malondialdehyde (MDA) level, tumor necrosis factor-α (TNF-α), interleukin-1beta (IL-1β), lipopolysaccharide (LPS) and caspase 3 were significantly increased. Likewise, immunohistochemical analysis revealed that TLR4 expression was elevated, whereas FXR expression was downregulated in hepatocytes. IAA substantially ameliorated all previously altered parameters, whereas CDCA treatment showed a partial improvement compared to IAA. Surprisingly, combination therapy of IAA with CDCA showed an additive effect only in the hepatic expression of TLR4 and FXR proteins.

SIGNIFICANCE

IAA could be a promising protective agent against VPA-induced liver injury.

Alterations in salivary biochemical composition and redox state disruption induced by the anticonvulsant valproic acid in male rat salivary glands

OBJECTIVE

To investigate the effects of the anticonvulsant valproic acid (VPA) on salivary glands in male rat using biochemical, functional, histomorphometric, and redox state parameters.

MATERIALS AND METHODS

Twenty-four male Wistar rats were randomly distributed into three groups (n = 8 per group): Control (0.9% saline solution), VPA100 (100 mg/kg), and VPA400 (400 mg/kg). After 21 consecutive days of treatment with by intragastric gavage. Pilocarpine-induced saliva was collected to determine salivary flow rate, pH, buffering capacity, and biochemical composition. Analyses of histomorphometric parameters and redox balance markers were performed on the parotid and submandibular glands.

RESULTS

Salivary flow rate, pH, buffering capacity, total protein, potassium, sodium, and chloride were similar between groups. However, phosphate and calcium were reduced in VPA400, while amylase was increased in both VPA100 and VPA400. We did not detect significant differences in the areas of acini, ducts, and connective tissue in the salivary glands between the groups. There were no significant changes in the redox status of the submandibular glands. In turn, in the parotid glands we detected reduced total oxidizing capacity and lipid peroxidation, measured as thiobarbituric acid reactive substances (TBARs) and higher uric acid concentration in both the VPA100 and VPA400 groups, and increased superoxide dismutase (SOD) in the VPA400 group.

CONCLUSION

Chronic treatment with VPA modified the salivary biochemical composition and caused disruption in the redox state of the parotid gland in rats.

Valproic Acid-Associated Hyperammonemia: A Systematic Review

BACKGROUND

Hyperammonemia is an adverse effect that poses clinical uncertainty around valproic acid (VPA) use. The prevalence of symptomatic and asymptomatic hyperammonemia and its relationship to VPA concentration is not well established. There is also no clear guidance regarding its management. This results in variability in the monitoring and treatment of VPA-induced hyperammonemia. To inform clinical practice, this systematic review aims to summarize evidence available around VPA-associated hyperammonemia and its prevalence, clinical outcomes, and management.

METHODS

An electronic search was performed through Ovid MEDLINE, Ovid Embase, Web of Science, and PsycINFO using search terms that identified hyperammonemia in patients receiving VPA. Two reviewers independently performed primary title and abstract screening with a third reviewer resolving conflicting screening results. This process was repeated during the full-text review process.

RESULTS

A total of 240 articles were included. Prevalence of asymptomatic hyperammonemia (5%-73%) was higher than symptomatic hyperammonemia (0.7%-22.2%) and occurred within the therapeutic range of VPA serum concentration. Various risk factors were identified, including concomitant medications, liver injury, and defects in carnitine metabolism. With VPA discontinued, most symptomatic patients returned to baseline mental status with normalized ammonia level. There was insufficient data to support routine monitoring of ammonia level for VPA-associated hyperammonemia.

CONCLUSIONS

Valproic acid-associated hyperammonemia is a common adverse effect that may occur within therapeutic range of VPA. Further studies are required to determine the benefit of routine ammonia level monitoring and to guide the management of VPA-associated hyperammonemia.

Absence of Increased Susceptibility to Acetaminophen-Induced Liver Injury in a Diet-Induced NAFLD Mouse Model

Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease and its influence on drug-induced liver injury (DILI) is not fully understood. We investigated whether NAFLD can influence acetaminophen (APAP [N-acetyl-p-aminophenol])-induced hepatotoxicity in a diet-induced obese (DIO) mouse model of NAFLD. The male C57BL/6NTac DIO mice, fed a high-fat diet for more than 12 weeks, developed obesity, hyperinsulinemia, impaired glucose tolerance, and hepatomegaly with hepatic steatosis, similar to human NAFLD. In the acute toxicity study after a single dose of APAP (150 mg/kg), compared with control lean mice, the DIO mice had decreased serum transaminase levels and less severe hepatocellular injury. The DIO mice also had altered expression of genes related to APAP metabolism. Chronic APAP exposure for 26 weeks did not predispose the DIO mice with NAFLD to more severe hepatotoxicity compared with the lean mice. These results suggested that the C57BL/6NTac DIO mouse model appears to be more tolerant to APAP-induced hepatotoxicity than lean mice, potentially related to altered xenobiotic metabolizing capacity in the fatty liver. Further mechanistic studies with APAP and other drugs in NAFLD animal models are necessary to investigate the mechanism of altered susceptibility to intrinsic DILI in some human NAFLD patients.

Sodium valproate exposure influences the expression of pparg in the zebrafish model

Valproic acid (VPA) is an anti-epileptic drug used alone or in combination with other medications to treat seizures, mania, and bipolar disorder. VPA recognized as a teratogenic chemical can cause severe birth defects mainly affecting the brain and spinal cord when administered during pregnancy. However, the potential mechanisms of developmental toxicity are still less studied, and in the present study, the influence of VPA exposure was evaluated on zebrafish early-life stages. Zebrafish were exposed to two sublethal concentrations of sodium valproate (SV) (0.06 mM and 0.15 mM) from 24 hours post-fertilization (hpf) to 96 hpf and the SV teratogenic potential was investigated through morphometric analysis of zebrafish larvae combined with the evaluation of cartilage profile. Moreover, the effect of SV on the transcription level of pparg was also performed. The results of the study showed the teratogenic potential of SV, which disrupts the morphometric signature of the head and body. The marked distortion of cartilage structures was paralleled to a malformation of telencephalon and optic tectum in both concentrations suggesting a high teratogen effect of SV on the brain. These data were further confirmed by the increased expression of pparg in the zebrafish head. Overall, the present study confirms the teratogenic activity of SV in the zebrafish model and, for the first time, points out the potential protective role of pparg in the SV dose-dependent toxicity.

Antioxidant-Based Preventive Effect of Phytochemicals on Anticancer Drug-Induced Hepatotoxicity

Significance: Drug-induced liver injury (DILI) or hepatotoxicity has been a hot issue to overcome on the safety and physiological function of the liver, since it is known to have biochemical, cellular, immunological, and molecular alterations in the liver mainly induced by alcohol, chemicals, drugs, heavy metals, and genetic factors. Recently efficient therapeutic and preventive strategies by some phytochemicals are of interest, targeting oxidative stress-mediated hepatotoxicity alone or in combination with anticancer drugs. Recent Advances: To assess DILI, the variety of in vitro and in vivo animal models has been developed mainly by using carbon tetrachloride, d-galactosamine, acetaminophen, and lipopolysaccharide. Also, the mechanisms on hepatotoxicity by several drugs and herbs have been explored in detail. Recent studies reveal that antioxidants including vitamins and some phytochemicals were reported to prevent against DILI. Critical Issues: Antioxidant therapy with some phytochemicals is noteworthy, since oxidative stress is critically involved in DILI via production of chemically reactive oxygen species or metabolites, impairment of mitochondrial respiratory chain, and induction of redox cycling. Future Directions: For efficient antioxidant therapy, DILI susceptibility, Human Leukocyte Antigen genetic factors, biomarkers, and pathogenesis implicated in hepatotoxicity should be further explored in association with oxidative stress-mediated signaling, while more randomized preclinical and clinical trials are required with optimal safe doses of drugs and/or phytochemicals alone or in combination for efficient clinical practice along with the development of advanced DILI diagnostic tools.

Neuroprotective Effects of Natural Antioxidants Against Branched-Chain Fatty Acid-Induced Oxidative Stress in Cerebral Cortex and Cerebellum Regions of the Rat Brain

Valproic acid (VPA) is short branched-chain fatty acid (BCFA) derived from valeric acids which are naturally produced by Valeriana officinalis (flowering plant). Neurotoxicity caused by BCFA-like VPA may be mediated by oxidative stress, according to research involving the cerebral cortex and cerebellum. In the present study, we explored the possible protective effect of different antioxidants such as melatonin, quercetin, and piperine on VPA exposure by using a supernatant preparation of the cerebral cortex and cerebellum regions of the rat brain. The present study revealed that melatonin, quercetin, and piperine significantly prevented VPA-induced oxidative stress in the cerebral cortex and cerebellum regions. VPA was also observed to lower the level of reduced glutathione, and this effect was significantly mitigated by these antioxidants. Melatonin, quercetin, and piperine also ameliorated and altered the activities of AChE, Na⁺, K⁺ATPase, and MAO in the cerebral cortex and cerebellum. Results of this study also suggest that prior treatment of antioxidants like melatonin, quercetin, and piperine helps in combating the oxidative stress induced by VPA in the cerebral cortex and cerebellum region of the rat brain. Thus, sufficient dietary intake of these antioxidants by individuals at high risk of VPA exposure could prove beneficial in combating the adverse effect of VPA.

Valproic acid induced liver injury: An insight into molecular toxicological mechanism

Valproic acid (VPA) is an anti-seizure drug that causes idiosyncratic liver injury. 2-propyl-4-pentenoic acid (Δ⁴VPA), a metabolite of VPA, has been implicated in VPA-induced hepatotoxicity. This review summarizes the pathogenesis involved in VPA-induced liver injury. The VPA induce liver injury mainly by i) liberation of Δ⁴VPA metabolites; ii) decrease in glutathione stores and antioxidants, resulting in oxidative stress; iii) inhibition of fatty acid β-oxidation, inducing mitochondrial DNA depletion and hypermethylation; a decrease in proton leak; oxidative phosphorylation impairment and ATP synthesis decrease; iv) induction of fatty liver via inhibition of carnitine palmitoyltransferase I, enhancing nuclear receptor peroxisome proliferator-activated receptor-gamma and acyl-CoA thioesterase 1, and inducing long-chain fatty acid uptake and triglyceride synthesis. VPA administration aggravates liver injury in individuals with metabolic syndromes. Therapeutic drug monitoring, routine serum levels of transaminases, ammonia, and lipid parameters during VPA therapy may thus be beneficial in improving the safety profile or preventing the progression of DILI.

A review: Systematic research approach on toxicity model of liver and kidney in laboratory animals

Therapeutic experiments are commonly performed on laboratory animals to investigate the possible mechanism(s) of action of toxic agents as well as drugs or substances under consideration. The use of toxins in laboratory animal models, including rats, is intended to cause toxicity. This study aimed to investigate different models of hepatotoxicity and nephrotoxicity in laboratory animals to help researchers advance their research goals. The current narrative review used databases such as Medline, Web of Science, Scopus, and Embase and appropriate keywords until June 2021. Nephrotoxicity and hepatotoxicity models derived from some toxic agents such as cisplatin, acetaminophen, doxorubicin, some anticancer drugs, and other materials through various signaling pathways are investigated. To understand the models of renal or hepatotoxicity in laboratory animals, we have provided a list of toxic agents and their toxicity procedures in this review.

Syringic acid and silymarin concurrent administration inhibits sodium valproate-induced liver injury in rats

Sodium valproate (SV) is a well-known anti-epileptic drug, also used to control convulsions, bipolar disorders and migraines. SV has been shown to induce liver toxicity in clinical subjects. Syringic acid (SA), a natural polyphenolic compound has potential antioxidant, anti-inflammatory and several beneficial effects. Therefore, in this study, we evaluated hepatoprotective effect of SA against SV-induced liver injury in rats. Wistar rats were treated with SV orally at a dose of 500 mg/kg, once daily, for 14 days. Another three groups of rats were administered with SV and concurrently treated with SA (40 and 80 mg/kg) and silymarin (SIL) (100 mg/kg) for 14 days. SV administration for 14 days caused significant (p < .001) elevation of liver transaminases and ALP in serum. Liver MDA level was significantly (p < .001) increased with a concomitant decrease (p < .001) in enzymic antioxidants activities in SV administered rats. SV administration also caused the upregulation of proinflammatory markers such as tumor necrosis factor α, c-Jun N-terminal kinase, nuclear factor kappa B, cyclooxygenase-2 and Interleukin 6 expressions in liver tissue. Histopathological studies also revealed the presence of inflammatory cell infiltration and hepatocellular necrosis upon SV administration. At both doses, concurrent administration of SA and SIL significantly (p < .001) inhibited the liver transaminase activities in serum, oxidative stress, and proinflammatory markers expression in liver tissue. Our current results suggest that SA can be a promising herbal drug that can inhibit SV-induced hepatotoxicity when administered together due its potential anti-inflammatory effects.

Metabolomics Provides Novel Insights into Epilepsy Diagnosis and Treatment: A Review

Epilepsy is one of the most common diseases of the central nervous system. The diagnosis of epilepsy mainly depends on electroencephalograms and symptomatology, while diagnostic biofluid markers are still lacking. In addition, approximately 30% of patients with epilepsy (PWE) show a poor response to the currently available anti-seizure medicines. An increasing number of studies have reported alterations in the blood, brain tissue, cerebrospinal fluid and urine metabolome in PWE and animal models of epilepsy. The aim of this review was to identify potential metabolic biomarkers and pathways that might facilitate diagnostic, therapeutic and prognostic determination in PWE and the understanding of the pathogenesis of the disease. The PubMed and Embase databases were searched for metabolomic studies of PWE and epileptic models published before December 2020. The study objectives, types of models and reported differentially altered metabolites were examined and compared. Pathway analyses were performed using MetaboAnalyst 5.0 online software. Thirty-five studies were included in this review. Metabolites such as glutamate, lactate and citrate were disturbed in both PWE and epileptic models, which might be potential biomarkers of epilepsy. Metabolic pathways including alanine, aspartate and glutamate metabolism; glycine, serine and threonine metabolism; glycerophospholipid metabolism; glyoxylate and dicarboxylate metabolism; and arginine and proline metabolism were involved in epilepsy. These pathways might play important roles in the pathogenesis of the disease. This review summarizes metabolites and metabolic pathways related to epilepsy and provides a novel perspective for the identification of potential biomarkers and therapeutic targets for epilepsy.

The Effect of Coenzyme Q10 on Liver Injury Induced by Valproic Acid and Its Antiepileptic Activity in Rats

Valproic acid (VPA) has toxic metabolites that can elevate oxidative stress markers, and the hepatotoxicity of VPA has been reported. Coenzyme Q10 (CoQ10) is one of the most widely used antioxidants. The effect of CoQ10 on epileptogenesis and VPA hepatotoxicity were examined. Rats were randomly divided into five groups: the control group received 0.5% methylcellulose by oral gavages daily and saline by intraperitoneal injection three times weekly. The PTZ group received 1% methylcellulose by gavages daily and 30 mg/kg PTZ by intraperitoneal injection three times weekly. The valproic acid group received 500 mg/kg valproic acid by gavage and 30 mg/kg PTZ, as above. The CoQ10 group received 200 mg/kg CoQ10 by gavages daily and 30 mg/kg PTZ, as above. The Valproic acid + CoQ10 group received valproic acid and CoQ10, as above. Results: CoQ10 exhibited anticonvulsant activity and potentiated the anticonvulsant effect of VPA. CoQ10 combined with VPA induced a more significant reduction in oxidative stress and improved the histopathological changes in the brain and liver compared to VPA treatment. In addition, CoQ10 reduced the level of toxic VPA metabolites. These findings suggest that the co-administration of CoQ10 with VPA in epilepsy might have therapeutic potential by increasing antiepileptic activity and reducing the hepatotoxicity of VPA.

Valproic Acid After Neurosurgery Induces Elevated Risk of Liver Injury: A Prospective Nested Case-Control Study

BACKGROUND

Valproic acid (VPA) has been widely used to prevent epileptic seizures after neurosurgery in China. We have found that the incidence of liver injury (LI) in patients using VPA after neurosurgery is higher than that in other patients.

OBJECTIVE

The objective of this study was to investigate the risk factors of LI in patients using VPA after neurosurgery.

METHODS

A nested case-control study was conducted in patients using VPA after neurosurgery between September 2019 and March 2021. Cases of LI were matched to controls by age and body mass index (BMI). Conditional logistic regression was used to estimate matched odds ratios representing the odds of LI. A receiver operating characteristic curve was used to analyze the optimal cutoff condition.

RESULTS

A total of 248 people (62 LI and 186 control) were enrolled. Among patients with vs without LI, the matched odds ratio for trough concentration of VPA was significant (matched odds ratio [OR], 1.09; 95% confidence interval [CI]: 1.01-1.19). The course of treatment (OR: 1.17, 95% CI: 1.02-1.33), Glasgow score (OR: 0.26, 95% CI: 0.10-0.67), gene polymorphisms of CYP2C19 (OR: 2.09, 95% CI: 1.03-146.93), and UGT1A6 (OR: 34.61, 95% CI: 1.19-1003.23) were all related to the outcome. The optimal cutoff of the course of treatment was 10 days, while the trough concentration of VPA was determined to be 66.16 mg/L.

CONCLUSION

Length of treatment, VPA trough concentration, and Glasgow score were associated with LI in patients after neurosurgery. A gene test may be necessary for people who are prescribed VPA for a long time.

A read-across case study on chronic toxicity of branched carboxylic acids (1): Integration of mechanistic evidence from new approach methodologies (NAMs) to explore a common mode of action

This read-across case study characterises thirteen, structurally similar carboxylic acids demonstrating the application of in vitro and in silico human-based new approach methods, to determine biological similarity. Based on data from in vivo animal studies, the read-across hypothesis is that all analogues are steatotic and so should be considered hazardous. Transcriptomic analysis to determine differentially expressed genes (DEGs) in hepatocytes served as first tier testing to confirm a common mode-of-action and identify differences in the potency of the analogues. An adverse outcome pathway (AOP) network for hepatic steatosis, informed the design of an in vitro testing battery, targeting AOP relevant MIEs and KEs, and Dempster-Shafer decision theory was used to systematically quantify uncertainty and to define the minimal testing scope. The case study shows that the read-across hypothesis is the critical core to designing a robust, NAM-based testing strategy. By summarising the current mechanistic understanding, an AOP enables the selection of NAMs covering MIEs, early KEs, and late KEs. Experimental coverage of the AOP in this way is vital since MIEs and early KEs alone are not confirmatory of progression to the AO. This strategy exemplifies the workflow previously published by the EUTOXRISK project driving a paradigm shift towards NAM-based NGRA.

Protective effects of naringin on valproic acid-induced hepatotoxicity in rats

Valproic acid (VPA) is mainly prescribed to treat epilepsy. VPA has been reported to be associated with many adverse effects, including hepatotoxicity. Naringin (NRG) is a natural, therapeutically active flavanone glycoside with anti-inflammatory, anti-apoptotic, and antioxidant. The current study was therefore designed to investigate the protective effect of NRG against the VPA-induced experimental hepatotoxicity model. For this purpose, 24 Wistar albino rats were randomly divided into three groups as control (Vehicle), VPA (500 mg/kg), and NRG + VPA (100 mg/kg NRG + 500 mg/kg VPA) groups. The agents were administered via oral gavage for 14 days. Blood and liver tissue samples were taken on the end of the experiment. Biochemical analyzes were performed on the blood and liver samples. Also, malondialdehyde (MDA), superoxide dismutase (SOD) enzyme, glutathione (GSH) content, catalase (CAT) enzyme levels were examined in the liver tissue samples. Histopathological changes (hydropic degeneration and congestion) in the VPA group were increased significantly when compared to the control group (p < 0.05). We also found a decrease in enzymes of serum liver function in the VPA group. However, NRG has been shown not to prevent histopathological changes in the VPA group. According to our results with this experiment protocol, NRG could not exert sufficient protection against VPA-induced hepatotoxicity.

Determination of in vitro metabolic hepatic clearance of valproic acid (VPA) and five analogues by UPLC-MS-QTOF, applicable in alternatives to animal testing

Laboratory measurements of intrinsic clearance support the development of TK models, with potential relevance to weight of evidence toxicity assessments of xenobiotics, including read-across, the concept of predictive estimation by data extrapolation between chemicals of similar structure (analogues). In this work a procedure with analytical method for determination of in vitro hepatic metabolic clearance, relevant to biotransformation toxicokinetic (TK) modelling, is presented. Cryopreserved primary human hepatocytes represent a suitable cells, due to their biological characteristics, for providing an in vitro model for simulating in vivo metabolic clearance. The experimental part considered an adequate sequential time-frame for collecting samples and controls for all chemicals tested, including centrifugation and aliquoting of the corresponding fractions until the instrumental session. For the first time, in vitro hepatocyte intrinsic clearance was measured for six analogue test chemicals: valproic acid, 2-ethyl caproic acid, octanoic acid, valeric acid, 2-methyl butyric acid and 2-trans pentenoic acid, during incubated cell culture exposure up to 2 h or 3.5 h. The time dependence of any metabolism was determined from analysis of the supernatant at intervals using a new developed analytical method for UPLC coupled with QTOF mass spectrometer. The chemicals could then be ranked by their relative intrinsic clearance. The analyses were reproducible, with coherence of the calculated in vitro intrinsic clearance between experiments.

Vitamin U prevents valproic acid-induced liver injury through supporting enzymatic antioxidant system and increasing hepatocyte proliferation triggered by inflammation and apoptosis

The aim of this study was to investigate the cellular mechanisms that cause valproic acid (VPA)-induced liver damage and the therapeutic effect of Vitamin U (Vit U) on these mechanisms. Female Sprague Dawley rats were randomly divided into four groups: intact control animals, animals that received Vit U (50 mg/kg/day), animals given VPA (500 mg/kg/day), and animals given both VPA and Vit U. The rats in the Vit U + VPA group were administered Vit U by gavage an hour before VPA administration every day for 15 days. Liver tissues were evaluated through histopathological, biochemical, immunohistochemical, and Western blotting techniques. Administration of Vit U with VPA resulted in (i) prevention of histopathological changes caused by VPA; (ii) blockage of the decrease in catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), and superoxide dismutase (SOD) activities; prevention of the elevation in gamma-glutamyl transferase (GGT) activity and advanced oxidation protein products (AOPP) level; (iii) increased in the levels of interleukin-1 beta (IL-1β), active caspase-3, and cytoplasmic cytochrome c; (iv) increase in cleaved poly (ADP-ribose) polymerase (PARP) level and decrease in LC3B (II/I) ratio; (v) increase in the number of proliferating cells nuclear antigen (PCNA) positive hepatocytes. These findings show that Vit U prevents liver damage caused by VPA through increasing the antioxidant enzyme capacity and hepatocyte proliferation by triggering inflammation and apoptosis. These findings suggest that Vit U provides its protective effects against VPA-induced liver damage by stimulating homeostasis and regeneration.

Taurine attenuates valproic acid-induced hepatotoxicity via modulation of RIPK1/RIPK3/MLKL-mediated necroptosis signaling in mice

Valproic acid (VPA) is known as a common drug in seizure and bipolar disorders treatment. Hepatotoxicity is the most important complication of VPA. Taurine (Tau), an amino acid, has antioxidant effects. The present research was conducted to evaluate the protective mechanisms of Tau on VPA-induced liver injury, especially focusing on the necroptosis signaling pathway. The sixty-four male NMRI mice were divided into eight groups with eight animals per each. The experiment groups pretreated with Tau (250, 500, 1000 mg/kg) and necrostatine-1 (Nec-1, 1.8 mg/kg) and then VPA (500 mg/kg) was administered for 14 consecutive days. The extent of VPA-induced hepatotoxicity was confirmed by elevated ALP (alkaline phosphatase), AST (aspartate aminotransferase), ALT (alanine aminotransferase) levels, and histological changes as steatosis, accumulation of erythrocytes, and inflammation. Additionally, VPA significantly induced oxidative stress in the hepatic tissue by increasing ROS (reactive oxygen species) production and lipid peroxidation level along with decreasing GSH (glutathione). Hepatic TNF-α (tumor necrosis factor) level, mRNA and protein expression of RIPK1 (receptor-interacting protein kinase 1), RIPK3, and MLKL (mixed lineage kinase domain-like pseudokinase) were upregulated. Also, the phosphorylation of MLKL and RIPK3 increased in the VPA group. Tau could effectively reverse these events. Our data suggest which necroptosis has a key role in the toxicity of VPA through TNF-α-mediated RIPK1/RIPK3/MLKL signaling and oxidative stress. Our findings suggest that Tau protects the liver tissue against VPA toxicity via inhibiting necroptosis signaling pathway mediated by RIPK1/RIPK3/MLKL and suppressing oxidative stress, and apoptosis.

Beyond Metabolism: Role of the Immune System in Hepatic Toxicity

The liver is primarily thought of as a metabolic organ; however, the liver is also an important mediator of immunological functions. Key perspectives on this emerging topic were presented in a symposium at the 2018 annual meeting of the American College of Toxicology entitled "Beyond metabolism: Role of the immune system in hepatic toxicity." Viral hepatitis is an important disease of the liver for which insufficient preventive vaccines exist. Host immune responses inadequately clear these viruses and often potentiate immunological inflammation that damages the liver. In addition, the liver is a key innate immune organ against bacterial infection. Hepatocytes and immune cells cooperatively control systemic and local bacterial infections. Conversely, bacterial infection can activate multiple types of immune cells and pathways to cause hepatocyte damage and liver injury. Finally, the immune system and specifically cytokines and drugs can interact in idiosyncratic drug-induced liver injury. This rare disease can result in a disease spectrum that ranges from mild to acute liver failure. The immune system plays a role in this disease spectrum.

Involvement of CYP2E1-ROS-CD36/DGAT2 axis in the pathogenesis of VPA-induced hepatic steatosis in vivo and in vitro

Valproic acid (VPA) is a widely prescribed antiepileptic drug, which may cause steatosis in the liver. Oxidative stress is associated with the progression of VPA-induced hepatic steatosis. However, the potential mechanisms are not fully understood. In this study, we demonstrated the involvement of CYP2E1-ROS-CD36/DGAT2 axis in the pathogenesis of VPA-induced hepatic steatosis in vitro and in vivo. First, VPA treatment (500 mg/kg in mice, 5 mM in LO₂ cells) induced hepatic steatosis and enhanced reactive oxidative stress (ROS) level, and ROS scavenger, N-acetyl-L-cysteine (NAC, 200 mg/kg in mice, 1 mM in LO₂ cells) reversed the changes. Next, we observed the enhanced expression and enzymatic activity of cytochrome P450 2E1 (CYP2E1) in VPA-treated mice and LO₂ cells. Importantly, VPA-induced ROS accumulation and hepatic steatosis were attenuated when CYP2E1 was inhibited using CYP2E1 inhibitor, diallyl sulfide (DAS, 100 mg/kg in mice, 1 mM in LO₂ cells) or in CYP2E1-knockdown cell line, suggesting that CYP2E1 plays a potential role in ROS production following hepatic steatosis. Furthermore, gene expression analysis showed that the mRNA levels of cluster of differentiation 36 (CD36), a fatty acid translocase protein and distinct diacylglycerol acyltransferase 2 (DGAT2) were significantly upregulated in mice and LO₂ cells after VPA treatment, while the change was alleviated by NAC and DAS. Meanwhile, time course experiments demonstrated that the increase of CYP2E1 level occurred earlier than that of ROS, CD36 and DGAT2, and ROS generation preceded the onset of hepatic steatosis. Taken together, VPA treatment enhances the expression and enzymatic activity of CYP2E1, which promotes ROS production and then causes CD36 and DGAT2 overproduction and hepatic steatosis in mice and LO₂ cells, which provides a novel insight into VPA-induced hepatic steatosis.

Obeticholic Acid Ameliorates Valproic Acid-Induced Hepatic Steatosis and Oxidative Stress

Farnesoid X receptor (FXR), or NR1H4, protects the liver from insults of various etiologies. A role of FXR in drug-induced liver injury has also been hypothesized yet only marginally investigated. The aim of this study was to assess the effect of FXR activation on gene expression and phenotype of the liver of mice treated with valproic acid (VPA), or 2-propylpentanoic acid, a prototypical hepatotoxic drug. Obeticholic acid (OCA) was used to activate FXR both in mice and in human hepatocellular carcinoma (Huh-7) cells. Next-generation sequencing of mouse liver tissues was performed from control, VPA, and VPA + OCA-treated mice. Pathway analysis validation was performed using real-time reverse-transcription polymerase chain reaction, Western blotting, immunohistochemistry, and fluorometric assays. FXR activation induced antioxidative pathways, which was confirmed by a marked reduction in VPA-induced lipid peroxidation and endoplasmic reticulum stress. In vitro, VPA-induced oxidative stress was independent of lipid accumulation, stemmed from the cytoplasm, and was mitigated by OCA. In the liver of the mice treated with OCA, the levels of cytochrome P450 potentially involved in VPA metabolism were increased. The hepatic lipid-lowering effect observed in animals cotreated with VPA and OCA in comparison with that of animals treated with VPA was associated with regulation of the genes involved in the steatogenic nuclear receptor peroxisome proliferator-activated γ (PPARγ) pathway. In conclusion, pronounced antioxidant activity, repression of the PPARγ pathway, and higher expression of P450 enzymes involved in VPA metabolism may underlie the hepatoprotective of FXR activation during VPA treatment. SIGNIFICANCE STATEMENT: Valproic acid-induced oxidative stress occurs in absence of lipid accumulation and is not of mitochondrial origin. Valproic acid exposure induces the expression of the steatogenic nuclear receptor peroxisome proliferator-activated γ (PPARγ) and its downstream target genes. Constitutive activation of the farnesoid X receptor (FXR) reduces PPARγ hepatic expression and induces hepatic antioxidant activity. The variability in FXR expression level/activity, for instance in individuals carrying loss-of-function genetic variants of the FXR gene, could contribute to valproic acid pharmacokinetic and toxicokinetic profile.

Valproic Acid and the Liver Injury in Patients with Epilepsy: An Update

BACKGROUND

Valproic acid (VPA) as a widely used primary medication in the treatment of epilepsy is associated with reversible or irreversible hepatotoxicity. Long-term VPA therapy is also related to increased risk for the development of non-alcoholic fatty liver disease (NAFLD). In this review, metabolic elimination pathways of VPA in the liver and underlying mechanisms of VPA-induced hepatotoxicity are discussed.

METHODS

We searched in PubMed for manuscripts published in English, combining terms such as "Valproic acid", "hepatotoxicity", "liver injury", and "mechanisms". The data of screened papers were analyzed and summarized.

RESULTS

The formation of VPA reactive metabolites, inhibition of fatty acid β-oxidation, excessive oxidative stress and genetic variants of some enzymes, such as CPS1, POLG, GSTs, SOD2, UGTs and CYPs genes, have been reported to be associated with VPA hepatotoxicity. Furthermore, carnitine supplementation and antioxidants administration proved to be positive treatment strategies for VPA-induced hepatotoxicity.

CONCLUSION

Therapeutic drug monitoring (TDM) and routine liver biochemistry monitoring during VPA-therapy, as well as genotype screening for certain patients before VPA administration, could improve the safety profile of this antiepileptic drug.

Butyrate prevents valproate-induced liver injury: In vitro and in vivo evidence

Sodium valproate (VPA), an antiepileptic drug, may cause dose- and time-dependent hepatotoxicity. However, its iatrogenic molecular mechanism and the rescue therapy are disregarded. Recently, it has been demonstrated that sodium butyrate (NaB) reduces hepatic steatosis, improving respiratory capacity and mitochondrial dysfunction in obese mice. Here, we investigated the protective effect of NaB in counteracting VPA-induced hepatotoxicity using in vitro and in vivo models. Human HepG2 cells and primary rat hepatocytes were exposed to high VPA concentration and treated with NaB. Mitochondrial function, lipid metabolism, and oxidative stress were evaluated, using Seahorse analyzer, spectrophotometric, and biochemical determinations. Liver protection by NaB was also evaluated in VPA-treated epileptic WAG/Rij rats, receiving NaB for 6 months. NaB prevented VPA toxicity, limiting cell oxidative and mitochondrial damage (ROS, malondialdehyde, SOD activity, mitochondrial bioenergetics), and restoring fatty acid oxidation (peroxisome proliferator-activated receptor α expression and carnitine palmitoyl-transferase activity) in HepG2 cells, primary hepatocytes, and isolated mitochondria. In vivo, NaB confirmed its activity normalizing hepatic biomarkers, fatty acid metabolism, and reducing inflammation and fibrosis induced by VPA. These data support the protective potential of NaB on VPA-induced liver injury, indicating it as valid therapeutic approach in counteracting this common side effect due to VPA chronic treatment.

Ginsenoside compound K alleviates sodium valproate-induced hepatotoxicity in rats via antioxidant effect, regulation of peroxisome pathway and iron homeostasis

Sodium valproate (SVP) is a first-line treatment for various forms of epilepsy; however, it can cause severe liver injury. Ginsenoside compound K (G-CK) is the main active ingredient of the traditional herbal medicine ginseng. According to our previous research, SVP-induced elevation of ALT and AST levels, as well as pathological changes of liver tissue, was believed to be significantly reversed by G-CK in LiCl-pilocarpine induced epileptic rats. Thus, we aimed to evaluate the protective effect of G-CK on hepatotoxicity caused by SVP. The rats treated with SVP showed liver injury with evident increases in hepatic index, transaminases activity, alkaline phosphatase level, hepatic triglyceride and lipid peroxidation; significant decreases in plasma albumin level and antioxidant capacity; and obvious changes in histopathological and subcellular structures. All of these changes could be mitigated by co-administration with G-CK. Proteomic analysis indicated that hepcidin, soluble epoxide hydrolase (sEH, UniProt ID P80299), and the peroxisome pathway were involved in the hepatoprotective effect of G-CK. Changes in protein expression of hepcidin and sEH were verified by ELISA and Western blot analysis, respectively. In addition, we observed that the hepatic iron rose in SVP group and decreased in the combination group. In summary, our findings demonstrate the clear hepatoprotective effect of G-CK against SVP-induced hepatotoxicity through the antioxidant effect, regulation of peroxisome pathway relying on sEH (P80299) downregulation, as well as regulation of iron homeostasis dependent on hepcidin upregulation.

Rhabdomyolysis and Hepatotoxicity From Valproic Acid: Case Reports

Valproic acid (VPA) has been widely used more frequently as its approved indications have been expanded. More and more case reports on rare toxicities have been published in the literature (ie, hepatotoxicities, hyperammonemic encephalopathy, coagulation disorders, pancreatitis, thrombocytopenia). In spite of the long history of VPA, there is a lack of awareness of VPA toxicities among clinicians. We present two cases of a 44-year-old African American female and a 60-year-old Hispanic male taking chronic VPA therapy for psychiatric disorders admitted to the hospital with a combination of hepatotoxicities and acute kidney injury-associated rhabdomyolysis. In both cases, home VPA therapy was continued during hospitalization. Consequently, the female patient deceased and the male patient survived and discharged with continuation of his chronic VPA therapy. In cases of surviving patients, resumption of maintenance VPA upon discharge should be held and alternative therapy should be considered.

Comparative analysis of isoform-specific and non-selective histone deacetylase inhibitors in attenuating the intestinal damage after hemorrhagic shock

BACKGROUND

Isoform-specific histone deacetylase inhibitors (HDACIs) MC1568 and ACY1083 are comparable to the non-selective HDACI valproic acid (VPA) in improving survival in rodents undergoing lethal hemorrhage. However, the organ-specific properties of isoform-specific HDACIs have not been fully evaluated. Also, whether they can act synergistically is not known. We hypothesized that isoform-specific HDACIs are superior to VPA in attenuating intestinal injury and act synergistically when coadministered.

METHODS

Sprague Dawley rats were hemorrhaged (40% of total blood volume) and randomized to receive (n=4 per group) (1) MC1568 (5 mg/kg), (2) ACY1083 (30 mg/kg), (3) MC1568+ACY1083 (combination: 5 mg/kg + 30 mg/kg, respectively), (4) VPA (250 mg/kg), or (5) normal saline (NS; vehicle; 250 μL). Animals were observed for 3 hours, after which blood samples were collected and samples of the ileum were harvested. Expression of interleukin 1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), and cytokine-induced neutrophil chemoattractant 1 (CINC-1) was assessed in the tissues using enzyme-linked immunosorbent assay. Intestinal cleaved caspase 3 (c-caspase 3) levels were assessed as a marker of apoptosis, and histologic sections of the ileum were examined for signs of bowel injury. Levels of IL-1β and TNF-α were also measured in the serum as global markers of inflammation.

RESULTS

Treatments with MC1568, ACY1083, MC1568+ACY1083, and VPA were associated with decreased IL-1β levels in the intestine and serum compared with NS. IL-1β and TNF-α levels were significantly lower in the ACY1083 group compared with the VPA group. CINC-1 levels were significantly lower in the isoform-specific HDACI groups compared with the NS; however, no significant differences were seen with VPA. All treatment groups had a lower expression of intestinal c-caspase 3 compared with NS. Furthermore, MC1568 and ACY1083 groups had lower apoptosis compared with the VPA group. Bowel injury scores were significantly lower in the isoform-specific HDACI groups compared with the NS group; however, the attenuation in the VPA-treated animals did not reach statistical significance.

DISCUSSION

Isoform-specific HDACIs provide superior intestinal protection compared with VPA in a rodent model of hemorrhagic shock.

LEVEL OF EVIDENCE

Preclinical study.

New Perspectives on Acyl Glucuronide Risk Assessment in Drug Discovery: Investigation of In vitro Stability, In situ Reactivity, and Bioactivation

Background:

Acyl glucuronides of xenobiotics have been a subject of wide interest from the pharmaceutical industry with respect to biochemical reactivity, hepatic disposition, and enterohepatic cir-culation. The reactivity and lack of stability of an acyl glucuronide for a clinical candidate could pose ma-jor developability concerns. To date, multiple in vitro assays have been published to assess the risk asso-ciated with acyl glucuronides. Despite this fact, the translation of these findings to predicting clinical safe-ty remains poor.

Methods:

In the present investigation, we aimed to provide simplified in vitro strategy to understand the bioactivation potential of acyl glucuronides of 10 commercial, carboxylic acid containing drugs that have been categorized as “safe,” “warning,” or “withdrawn” with respect to their marketed use. Acyl migration was measured as a function of the number of peaks observed in LC-MSn analysis. In addition, we carried out reactive intermediate trapping studies with glutathione and methoxylamine to identify the key interme-diates in the transacylation bioactivation and glycation pathways, respectively. We also conducted reaction phenotyping with recombinant UDP-glucuronosyltransferase (UGT) Supersomes® to investigate if the formation of acyl glucuronides could be linked to specific UGT isoform(s).

Results:

Our results were in line with reported values in the literature. Our assay could be used in discov-ery research where half-life calculation completely eliminated the need to chemically synthesize the acyl glucuronide standard for risk assessment. We captured our results for risk assessment in a flow chart to simplify the various complex in vitro techniques historically presented.

Conclusion:

While the compounds tested from “withdrawn” and “warning category” all formed the glu-tathione adduct in buffer, none from “safe” category formed the glutathione adduct. In contrast, none of the compounds tested from any category formed methoxylamine conjugate, a reaction with putative alde-hyde moiety formed via acyl migration. These results, highly favor the nucleophilic displacement as a cause of the reactivity rather than the acyl migration via aldehyde formation. The workflow presented could also be applied in the discovery setting to triage new chemical entities of interest.

The footprints of mitochondrial impairment and cellular energy crisis in the pathogenesis of xenobiotics-induced nephrotoxicity, serum electrolytes imbalance, and Fanconi's syndrome: A comprehensive review

Fanconi's Syndrome (FS) is a disorder characterized by impaired renal proximal tubule function. FS is associated with a vast defect in the renal reabsorption of several chemicals. Inherited and/or acquired conditions seem to be connected with FS. Several xenobiotics including many pharmaceuticals are capable of inducing FS and nephrotoxicity. Although the pathological state of FS is well described, the exact underlying etiology and cellular mechanism(s) of xenobiotics-induced nephrotoxicity, serum electrolytes imbalance, and FS are not elucidated. Constant and high dependence of the renal reabsorption process to energy (ATP) makes mitochondrial dysfunction as a pivotal mechanism which could be involved in the pathogenesis of FS. The current review focuses on the footprints of mitochondrial impairment in the etiology of xenobiotics-induced FS. Moreover, the importance of mitochondria protecting agents and their preventive/therapeutic capability against FS is highlighted. The information collected in this review may provide significant clues to new therapeutic interventions aimed at minimizing xenobiotics-induced renal injury, serum electrolytes imbalance, and FS.

Effects of levetiracetam and valproic acid treatment on liver function tests, plasma free carnitine and lipid peroxidation in childhood epilepsies

BACKGROUND AND AIMS

The relationship between anti-epileptic usage and oxidative damage has not yet been clearly understood. In our study, we investigated oxidative stress parameters, carnitine levels, liver function tests (LFT) and their relationship in epileptic children treated with valproic acid or levetiracetam.

METHOD

LFTs, serum free carnitine and oxidative damage markers and their relations with each other were determined in patients who are on valproic acid or levetiracetam treatment at least for 6 months. 25 patients on therapeutic doses of valproic acid, 26 patients on therapeutic doses of levetiracetam and 26 healthy volunteers as controls were included. LFTs, ammonia, carnitine, lipid peroxidation biomarker malondialdehyde (MDA) and a sensitive marker of DNA damage, 8-hydroxy-2-deoxyguanosine (8-OHdG) levels were measured. Results of patients are compared to healthy controls. The data is evaluated with IBM SPSS Statistics 22.0.

RESULTS

Ammonia and MDA levels were elevated in patients using levetiracetam; 8-OHdG levels were elevated in both patient groups. Carnitine levels were significantly low in patients under valproic acid therapy, however they were not found to be correlated with MDA, 8-OHdG or LFTs. MDA showed positive correlation with ammonia and 8-OHdG in the levetiracetam group.

CONCLUSION

We did not observe hepatotoxicity in patients under therapeutic doses of valproic acid. However, epileptic children under therapeutic doses of levetiracetam showed significantly elevated levels of MDA and 8-OHdG, which is supportive for oxidative damage under levetiracetam therapy. This result was observed for the first time in childhood epilepsies and further studies are needed to understand its mechanism.

Effects of antiepileptic drugs on dynamic thiol/disulphide homeostasis in children with idiopathic epilepsy

PURPOSE

Anti-epileptic drugs have been widely used in children with epilepsy. Although several studies have investigated the role of oxidative stress and the effects of antiepileptic drugs on several oxidative markers in epilepsy, adequate information is not available on this issue. This study aimed to investigate the changes in thiol disulphide homeostasis in children with epilepsy under two commonly prescribed AED monotherapies, carbamazepine and valproic acid.

METHODS

A hundred and one children with epilepsy using valproic acid or carbamazepine and 58 healthy children were included in this study. Of the 101 patients with idiopathic epilepsy, 58 were on valproic acid monotherapy and 43 patients were on carbamazepine monotherapy. The total thiol, native thiol, and disulphide levels were measured and the disulphide/native thiol, disulphide/total thiol and native thiol/total thiol ratios were calculated in both groups.

RESULTS

The total thiol and native thiol levels of the valproic acid treated group were significantly lower than the control group (p < 0.05). The native thiol level of carbamazepine treated group was lower than the control group without a significance (p = 0.123). Disulphide level, disulphide/native thiol and disulphide/total thiol ratios were significantly higher and native thiol/total thiol ratio was significantly lower in both valproic acid and carbamazepine treated group compared with the control group.

CONCLUSION

Thiol/disulphide homeostasis is impaired in children with idiopathic epilepsy using valproic acid or carbamazepine. Valproic acid which is frequently used in childhood epilepsy may modify this balance more than carbamazepine monotherapy. More importantly, the new method used in our study proposes a promising, practical and daily applicable test for evaluating oxidative stress in these patien.

Valproic acid induced acute liver injury resulting in hepatic encephalopathy- a case report and literature review

Valproic acid (VPA) is a commonly used agent in the management of seizures and psychiatric disorders. Hyperammonemia is a common complication of VPA with 27.8% of patients having elevated levels – that is unrelated to hepatotoxicity and normal transaminases. Common side effects include obesity, insulin resistance, metabolic disorder and severe forms of hepatotoxicity. Other rare and idiosyncratic reactions have been reported, one of which is presented in our case. A 27-year old patient presented with hyperammonemia and encephalopathy as a consequence of idiosyncratic VPA reaction causing drug-induced liver injury (DILI) with severely elevated transaminases. DILI is commonly overlooked when investigating encephalopathy in the setting of VPA. Physicians should consider DILI in the context of hyperammonemia and transaminitis.

Mechanism of valproic acid-induced Fanconi syndrome involves mitochondrial dysfunction and oxidative stress in rat kidney

AIM

Drug-induced kidney proximal tubular injury and renal failure (Fanconi syndrome; FS) is a clinical complication. Valproic acid (VPA) is among the FS-inducing drugs. The current investigation was designed to evaluate the role of mitochondrial dysfunction and oxidative stress in VPA-induced renal injury.

METHODS

Animals received VPA (250 and 500 mg/kg, i.p., 15 consecutive days). Serum biomarkers of kidney injury and markers of oxidative stress were assessed. Moreover, kidney mitochondria were isolated and mitochondrial indices, including succinate dehydrogenase activity (SDA), mitochondrial depolarization, mitochondrial permeability transition pore (MPP), reactive oxygen species (ROS), lipid peroxidation (LPO), mitochondrial glutathione, and ATP were determined.

RESULTS

Valproic acid-treated animals developed biochemical evidence of FS as judged by elevated serum gamma-glutamyl transferase (γ-GT), alkaline phosphatase (ALP), creatinine (Cr), and blood urea nitrogen (BUN) along with hypokalaemia, hypophosphataemia, and a decrease in serum uric acid. VPA caused an increase in kidney ROS and LPO. Renal GSH reservoirs were depleted and tissue antioxidant capacity decreased in VPA-treated animals. Renal tubular interstitial nephritis, tissue necrosis, and atrophy were also evident in VPA-treated rats. Mitochondrial parameters including SDA, MMP, GSH, ATP and MPP were decreased and mitochondrial ROS and LPO were increased with VPA treatment. It was found that carnitine (100 mg/kg, i.p.) mitigated VPA adverse effects towards the kidney.

CONCLUSIONS

These data suggest that mitochondrial dysfunction and oxidative stress contributed to the VPA-induced FS. On the other hand, carnitine could be considered a potentially safe and effective therapeutic option in attenuating VPA-induced renal injury.

Comparison of base-line and chemical-induced transcriptomic responses in HepaRG and RPTEC/TERT1 cells using TempO-Seq

The utilisation of genome-wide transcriptomics has played a pivotal role in advancing the field of toxicology, allowing the mapping of transcriptional signatures to chemical exposures. These activities have uncovered several transcriptionally regulated pathways that can be utilised for assessing the perturbation impact of a chemical and also the identification of toxic mode of action. However, current transcriptomic platforms are not very amenable to high-throughput workflows due to, high cost, complexities in sample preparation and relatively complex bioinformatic analysis. Thus, transcriptomic investigations are usually limited in dose and time dimensions and are, therefore, not optimal for implementation in risk assessment workflows. In this study, we investigated a new cost-effective, transcriptomic assay, TempO-Seq, which alleviates the aforementioned limitations. This technique was evaluated in a 6-compound screen, utilising differentiated kidney (RPTEC/TERT1) and liver (HepaRG) cells and compared to non-transcriptomic label-free sensitive endpoints of chemical-induced disturbances, namely phase contrast morphology, xCELLigence and glycolysis. Non-proliferating cell monolayers were exposed to six sub-lethal concentrations of each compound for 24 h. The results show that utilising a 2839 gene panel, it is possible to discriminate basal tissue-specific signatures, generate dose-response relationships and to discriminate compound-specific and cell type-specific responses. This study also reiterates previous findings that chemical-induced transcriptomic alterations occur prior to cytotoxicity and that transcriptomics provides in depth mechanistic information of the effects of chemicals on cellular transcriptional responses. TempO-Seq is a robust transcriptomic platform that is well suited for in vitro toxicity experiments.

Noncovalent interactions dominate dynamic heme distortion in cytochrome P450 4B1

Cytochrome P450 4B1 (4B1) functions in both xenobiotic and endobiotic metabolism. An ester linkage between Glu-310 in 4B1 and the 5-methyl group of heme facilitates preferential hydroxylation of terminal (ω) methyl groups of hydrocarbons (HCs) and fatty acids compared with ω-1 sites bearing weaker C-H bonds. This preference is retained albeit diminished 4-fold for the E310A mutant, but the reason for this is unclear. Here, a crystal structure of the E310A-octane complex disclosed that noncovalent interactions maintain heme deformation in the absence of the ester linkage. Consistent with the lower symmetry of the heme, resonance Raman (RR) spectroscopy revealed large enhancements of RR peaks for high-spin HC complexes of 4B1 and the E310A mutant relative to P450 3A4. Whereas these enhancements were diminished in RR spectra of a low-spin 4B1-N-hydroxy-N'-(4-butyl-2-methylphenyl)formamidine complex, a crystal structure indicated that this inhibitor does not alter heme ruffling. RR spectra of Fe2+-CO HC complexes revealed larger effects of HC length in E310A than in 4B1, suggesting that reduced rigidity probably underlies increased E310A-catalyzed (ω-1)-hydroxylation. Diminished effects of the HC on the position of the Fe-CO stretching mode in 4B1 suggested that the ester linkage limits substrate access to the CO. Heme ruffling probably facilitates autocatalytic ester formation by reducing inhibitory coordination of Glu-310 with the heme iron. This also positions the 5-methyl for a reaction with the proposed glutamyl radical intermediate and potentially enhances oxo-ferryl intermediate reactivity for generation of the glutamyl radical to initiate ester bond formation and ω-hydroxylation.

Integrated 'omics analysis reveals new drug-induced mitochondrial perturbations in human hepatocytes

We performed a multiple 'omics study by integrating data on epigenomic, transcriptomic, and proteomic perturbations associated with mitochondrial dysfunction in primary human hepatocytes caused by the liver toxicant valproic acid (VPA), to deeper understand downstream events following epigenetic alterations in the mitochondrial genome. Furthermore, we investigated persistence of cross-omics changes after terminating drug treatment. Upon transient methylation changes of mitochondrial genes during VPA-treatment, increasing complexities of gene-interaction networks across time were demonstrated, which normalized during washout. Furthermore, co-expression between genes and their corresponding proteins increased across time. Additionally, in relation to persistently decreased ATP production, we observed decreased expression of mitochondrial complex I and III-V genes. Persistent transcripts and proteins were related to citric acid cycle and β-oxidation. In particular, we identified a potential novel mitochondrial-nuclear signaling axis, MT-CO2-FN1-MYC-CPT1. In summary, this cross-omics study revealed dynamic responses of the mitochondrial epigenome to an impulse toxicant challenge resulting in persistent mitochondrial dysfunctioning. Moreover, this approach allowed for discriminating between the toxic effect of VPA and adaptation.

Valproic acid disrupts the oscillatory expression of core circadian rhythm transcription factors

Valproic acid (VPA) is a well-established therapeutic used in treatment of seizure and mood disorders as well as migraines and a known hepatotoxicant. About 50% of VPA users experience metabolic disruptions, including weight gain, hyperlipidemia, and hyperinsulinemia, among others. Several of these metabolic abnormalities are similar to the effects of circadian rhythm disruption. In the current study, we examine the effect of VPA exposure on the expression of core circadian transcription factors that drive the circadian clock via a transcription-translation feedback loop. In cells with an unsynchronized clock, VPA simultaneously upregulated the expression of genes encoding core circadian transcription factors that regulate the positive and negative limbs of the feedback loop. Using low dose glucocorticoid, we synchronized cultured fibroblast cells to a circadian oscillatory pattern. Whether VPA was added at the time of synchronization or 12h later at CT12, we found that VPA disrupted the oscillatory expression of multiple genes encoding essential transcription factors that regulate circadian rhythm. Therefore, we conclude that VPA has a potent effect on the circadian rhythm transcription-translation feedback loop that may be linked to negative VPA side effects in humans. Furthermore, our study suggests potential chronopharmacology implications of VPA usage.

Nuclear and Mitochondrial DNA Methylation Patterns Induced by Valproic Acid in Human Hepatocytes

Valproic acid (VPA) is one of the most widely prescribed antiepileptic drugs in the world. Despite its pharmacological importance, it may cause liver toxicity and steatosis through mitochondrial dysfunction. The aim of this study is to further investigate VPA-induced mechanisms of steatosis by analyzing changes in patterns of methylation in nuclear DNA (nDNA) and mitochondrial DNA (mtDNA). Therefore, primary human hepatocytes (PHHs) were exposed to an incubation concentration of VPA that was shown to cause steatosis without inducing overt cytotoxicity. VPA was administered daily for 5 days, and this was followed by a 3 day washout (WO). Methylated DNA regions (DMRs) were identified by using the methylated DNA immunoprecipitation–sequencing (MeDIP-seq) method. The nDNA DMRs after VPA treatment could indeed be classified into oxidative stress- and steatosis-related pathways. In particular, networks of the steatosis-related gene EP300 provided novel insight into the mechanisms of toxicity induced by VPA treatment. Furthermore, we suggest that VPA induces a crosstalk between nDNA hypermethylation and mtDNA hypomethylation that plays a role in oxidative stress and steatosis development. Although most VPA-induced methylation patterns appeared reversible upon terminating VPA treatment, 31 nDNA DMRs (including 5 zinc finger protein genes) remained persistent after the WO period. Overall, we have shown that MeDIP-seq analysis is highly informative in disclosing novel mechanisms of VPA-induced toxicity in PHHs. Our results thus provide a prototype for the novel generation of interesting methylation biomarkers for repeated dose liver toxicity in vitro.

Zinc Deficiency and Oxidative Stress Involved in Valproic Acid Induced Hepatotoxicity: Protection by Zinc and Selenium Supplementation

Valproic acid (VPA) is an antiepileptic drug, which its usage is limited due to its hepatotoxicity. The present study was conducted to investigate the efficacy of zinc (Zn) and selenium (Se), necessary trace elements, against VPA-induced hepatotoxicity in Wistar rats. The animals were divided into five groups: control, VPA 200 mg/kg, VPA + Zn (100 mg/kg), VPA + Se (100 mg/kg), and VPA + Zn + Se. The administration of VPA for four consecutive weeks resulted in decrease in serum level of Zn in rats. Also, an increase in liver marker enzymes (ALT and AST) and also histological changes in liver tissue were shown after VPA administration. Oxidative stress was evident in VPA group by increased lipid peroxidation (LPO), protein carbonyl (PCO), glutathione (GSH) oxidation, and reducing total antioxidant capacity. Zn and Se (100 mg/kg) administration was able to protect against deterioration in liver enzyme, abrogated the histological change in liver tissue, and suppressed the increase in oxidative stress markers. Zn and combination of Zn plus Se treatment showed more protective effects than Se alone. These results imply that Zn and Se should be suggested as effective supplement products for the prevention of VPA-induced hepatotoxicity.

Sex-related differences of urethane and sodium valproate effects on Ki-67 expression in urethane-induced lung tumors of mice

The aim of the present study was to evaluate sex differences in tumorigenesis by assessing the number of Ki-67-positive cells [Ki-67(+)] in urethane-induced mice lung tumors and the effect of sodium valproate (NaVP) in BALB/c mice. Gonad-intact and gonadectomized female and male mice were divided into the following groups: i) Treated with urethane, ii) treated with urethane and NaVP and iii) gonad-intact or gonadectomized control. Urethane (total 50 mg/mouse) was injected intraperitoneally. The NaVP 0.4% solution was administered orally for 6 months. Histologically, lung tumors were divided into adenomas and adenocarcinomas and assessed immunohistochemically using antibodies against Ki-67. The Ki-67(+) was calculated per one mm² of a tumor. In adenomas, Ki-67(+) in the urethane-treated gonad-intact males was significantly higher than in females (P=0.001) and in castrated males (P<0.01); Ki-67(+) in adenomas of the urethane-treated gonad-intact males was significantly higher than in urethane-NaVP-treated ones (P<0.04). No significant differences were found in analogous female groups. In adenocarcinomas, Ki-67(+) in urethane-treated gonad-intact males was significantly higher than in females and gonadectomized mice of both sexes (P<0.001), and in ovariectomized females was significantly higher than in ovary-intact group (P=0.01). A significantly higher number of Ki-67(+) cells were observed in gonad-intact adenocarcinomas of the urethane-NaVP-treated females compared with the urethane-treated ones (P<0.001). Comparing between urethane-NaVP-treated gonadectomized males and females in adenocarcinomas, determined that Ki-67(+) was significantly lower in females (P=0.005). In adenocarcinomas, Ki-67(+) in urethane-NaVP-treated gonadectomized males and females was significantly lower than in gonad-intact mice of the same sex (P<0.001). In summary, gonadectomy with NaVP treatment decreased Ki-67(+) in adenocarcinomas for mice of both sexes. The results of the present study indicate sex-related differences in mice lung tumorigenesis, and a sex-related effect of NaVP on progression in urethane-induced BALB/c mice lung tumors.