M1 muscarinic receptors modify oxidative stress response to acetaminophen-induced acute liver injury

Hepatotoxicity of antipsychotics: an exploratory pharmacoepidemiologic and pharmacodynamic study integrating FAERS data and in vitro receptor-binding affinities

Introduction

Antipsychotic psychopharmacotherapy is associated with the risk of drug-induced liver injury (DILI). However, understanding specific risk factors remains challenging due to limited data. This study investigates the relationship between receptor binding affinities and occupancies of antipsychotics and their associated hepatotoxic risks.

Methods

A disproportionality analysis with calculation of the Reporting Odds Ratio (ROR) and the Information Component (IC) was conducted using data from the FDA Adverse Event Reporting System (FAERS) to identify signals related to the Standardised MedDRA Query "drug-related hepatic disorders", which served as a proxy for drug-induced hepatotoxicity. This was followed by a pharmacoepidemiologic-pharmacodynamic approach to investigate the relationship between the ROR and substance-related receptor binding affinities and occupancy, which was estimated based on in vitro receptor-binding profiles.

Results

Significant signals were identified for several antipsychotics, including chlorpromazine, loxapine, olanzapine, and quetiapine, with chlorpromazine and loxapine showing the highest RORs for DILI. Gender-specific analysis revealed a higher frequency of signals in female patients. Statistically significant negative correlations were identified between the ROR for drug-related hepatic disorders and the affinity for serotonin receptor 5-HT1A (r (17) = -0.68, p = 0.0012), while a positive correlation was observed for cholinergic receptors (r (17) = 0.46, p = 0.048). No significant correlations were found related to other receptors or drug properties.

Conclusion

Our findings suggest that the serotonin and probably the cholinergic system may play a role in the development of DILI related to antipsychotic medications. The identification of antipsychotics with a higher association with DILI, such as chlorpromazine, underscores the need for careful monitoring in clinical practice. However, our findings need further longitudinal studies to confirm causality. A better understanding of the associations may inform clinical decision-making, particularly in patients with an increased susceptibility to liver damage.

Investigation of the General Molecular Mechanisms of Gallic Acid via Analyses of Its Transcriptome Profile

Gallic acid (GA), a phenolic compound naturally found in many plants, exhibits potential preventive and therapeutic roles. However, the underlying molecular mechanisms of its diverse biological activities remain unclear. Here, we investigated possible mechanisms of GA function through a transcriptome-based analysis using LINCS L1000, a publicly available data resource. We compared the changes in the gene expression profiles induced by GA with those induced by FDA-approved drugs in three cancer cell lines (A549, PC3, and MCF7). The top 10 drugs exhibiting high similarity with GA in their expression patterns were identified by calculating the connectivity score in the three cell lines. We specified the known target proteins of these drugs, which could be potential targets of GA, and identified 19 potential targets. Next, we retrieved evidence in the literature that GA likely binds directly to DNA polymerase β and ribonucleoside-diphosphate reductase. Although our results align with previous studies suggesting a direct and/or indirect connection between GA and the target proteins, further experimental investigations are required to fully understand the exact molecular mechanisms of GA. Our study provides insights into the therapeutic mechanisms of GA, introducing a new approach to characterizing therapeutic natural compounds using transcriptome-based analyses.

Sting mutation attenuates acetaminophen-induced acute liver injury by limiting NLRP3 activation

Acetaminophen (N-acetyl-p-aminophenol; APAP), a widely used effective nonsteroidal anti-inflammatory drug, leads to acute liver injury at overdose worldwide. Evidence showed that the severity of liver injury associated with the subsequent involvement of inflammatory mediators and immune cells. The innate immune stimulator of interferon genes protein (STING) pathway was critical in modulating inflammation. Here, we show that STING was activated and inflammation was enhanced in the liver in APAP-overdosed C57BL/6J mice, and Sting mutation (Stinggt/gt) mice exhibited less liver damage. Multiplexing flow cytometry displayed that Sting mutation changed hepatic recruitment and replacement of macrophages/monocytes in APAP-overdosed mice, which was inclined to anti-inflammation. In addition, Sting mutation limited NLRP3 activation in the liver in APAP-overdosed mice, and inhibited the expression of inflammatory cytokines. Finally, MCC950, a potent and selective NLRP3 inhibitor, significantly ameliorated APAP-induced liver injury and inflammation. Besides, pretreatment of MCC950 in C57 mice resulted in changes of immune cells infiltration in the liver similar to Stinggt/gt mice. Our study revealed that STING played a crucial role in APAP-induced acute liver injury, possibly by maintaining liver immune cells homeostasis and inhibiting NLRP3 inflammasome activation, suggesting that inhibiting STING-NLRP3 pathway might be a potential therapeutic strategy for acute liver injury.

Muscarinic receptor agonist-induced βPix binding to β-catenin promotes colon neoplasia

M3 muscarinic receptors (M3R) modulate β-catenin signaling and colon neoplasia. CDC42/RAC guanine nucleotide exchange factor, βPix, binds to β-catenin in colon cancer cells, augmenting β-catenin transcriptional activity. Using in silico, in vitro, and in vivo approaches, we explored whether these actions are regulated by M3R. At the invasive fronts of murine and human colon cancers, we detected co-localized nuclear expression of βPix and β-catenin in stem cells overexpressing M3R. Using immunohistochemistry, immunoprecipitation, proximity ligand, and fluorescent cell sorting assays in human tissues and established and primary human colon cancer cell cultures, we detected time-dependent M3R agonist-induced cytoplasmic and nuclear association of βPix with β-catenin. βPix knockdown attenuated M3R agonist-induced human colon cancer cell proliferation, migration, invasion, and expression of PTGS2, the gene encoding cyclooxygenase-2, a key player in colon neoplasia. Overexpressing βPix dose-dependently augmented β-catenin binding to the transcription factor TCF4. In a murine model of sporadic colon cancer, advanced neoplasia was attenuated in conditional knockout mice with intestinal epithelial cell deficiency of βPix. Expression levels of β-catenin target genes and proteins relevant to colon neoplasia, including c-Myc and Ptgs2, were reduced in colon tumors from βPix-deficient conditional knockout mice. Targeting the M3R/βPix/β-catenin axis may have therapeutic potential.

The relationship between the cholinergic mechanism of toxicity and oxidative stress in rats during subacute diazinon poisoning

Diazinon is an organophosphate pesticide (OP) that has significant potential for accidental and intentional poisoning of wildlife, domestic animals and humans. The aim of the study is to investigate the correlation between cholinesterase activity and oxidative stress parameters in liver and diaphragm by continuous monitoring as a function of time during prolonged use of diazinon. Wistar rats were treated orally with diazinon (55 mg/kg/day): 7, 14, 21 and 28 days. At the end of each period, blood, liver and diaphragm were collected to examine cholinesterase activity and enzymatic/non-enzymatic oxidative stress parameters: superoxide dismutase 1 (SOD1), catalase (CAT), thiobarbituric acid substances (TBARS), protein carbonyl groups. In all four time periods, there was a significant change in acetylcholinesterase (AChE) in erythrocytes and butyrylcholinesterase (BuChE) in blood plasma, CAT in liver and diaphragm and SOD1 in diaphragm. Parameters significantly altered during the cholinergic crisis included: cholinesterases and TBARS in liver and diaphragm and partially SOD1 in liver. Protein carbonyl groups in liver and diaphragm were significantly altered outside the cholinergic crisis. In the liver, there was a very strong negative correlation between BuChE and TBARS in all four time periods and BuChE and CAT on day 7. In the diaphragm, a very strong negative correlation was found between AChE and TBARS at days 7 and 14, and a very strong positive correlation between AChE and SOD1 at days 14, 21 and 28. A better understanding of the relationship between cholinergic overstimulation and oxidative stress may help to better assess health status in prolonged OPs intoxication.

Procyanidins Ameliorate Acetaminophen-induced Acute Liver Injury via Activating the Nrf-2/SOD-1 Signal Pathway

Background and Objectives

An overdose of acetaminophen (APAP) usually leads to acute liver injury, and oxidative stress is one of the fundamental mechanisms used to characterize it. Procyanidins (PCs) can reduce the oxidative stress in the liver of mice. This study aimed to investigate the potential protective role of PCs against APAP-induced acute liver injury.

Materials and Methods

Experiments were performed on male Kunming mice in six groups: phosphate-buffered saline, PCs, APAP, and PCs pretreated with 10, 50, and 100 mg/kg. The mice were peritoneally injected with PCs 30 min before the administration of APAP. First, survival rates of mice were scored every 12 hr for three days in succession. Furthermore, serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (T-Bil), total cholesterol (TC), triglyceride (TG), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-1 (IL-6) were determined. Additionally, histological analysis and hepatic oxidative stress including the levels of superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione (GSH) were assessed. Finally, the protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and SOD-1 was detected by Western blotting.

Results

The data indicated that PCs improved survival rates of APAP-induced liver injury in mice models. Moreover, PCs could reduce the elevated serum levels of ALT, AST, T-Bil, TC, TG, TNF-α, IL-1β, and IL-6 due to APAP exposure with a dose-dependent manner. Besides, PCs pretreatment attenuated hepatic histopathological damage and oxidative stress which manifested the increases of SOD and GSH, whereas the decrease of MDA. Furthermore, PCs enhanced the protein expression of Nrf2 and SOD-1 in the PCs pretreatment groups compared with the APAP group.

Conclusion

PCs ameliorated APAP-induced acute liver injury, and Nrf2 signaling pathway modulating antioxidative stress might be involved in it.

The molecular mechanisms of acetaminophen-induced hepatotoxicity and its potential therapeutic targets

Acetaminophen (APAP), a widely used antipyretic and analgesic drug in clinics, is relatively safe at therapeutic doses; however, APAP overdose may lead to fatal acute liver injury. Currently, N-acetylcysteine (NAC) is clinically used as the main antidote for APAP poisoning, but its therapeutic effect remains limited owing to rapid disease progression and the general diagnosis of advanced poisoning. As is well known, APAP-induced hepatotoxicity (AIH) is mainly caused by the toxic metabolite N-acetyl-p-benzoquinone imine (NAPQI), and the toxic mechanisms of AIH are complicated. Several cellular processes are involved in the pathogenesis of AIH, including liver metabolism, mitochondrial oxidative stress and dysfunction, sterile inflammation, endoplasmic reticulum stress, autophagy, and microcirculation dysfunction. Mitochondrial oxidative stress and dysfunction are the major cellular events associated with APAP-induced liver injury. Many biomolecules involved in these biological processes are potential therapeutic targets for AIH. Therefore, there is an urgent need to comprehensively clarify the molecular mechanisms underlying AIH and to explore novel therapeutic strategies. This review summarizes the various cellular events involved in AIH and discusses their potential therapeutic targets, with the aim of providing new ideas for the treatment of AIH.

Nilotinib alleviated acetaminophen-induced acute hepatic injury in mice through inhibiting HIF-1alpha/VEGF-signaling pathway

The current study inspects the impact of nilotinib (Nil) on liver damage caused by acetaminophen (APAP). Adult male mice were pre-treated with nilotinib (Nil,5 and 10 mg/kg) orally once daily for 7 days followed by a single intraperitoneal administration of acetaminophen (APAP, 200 mg/kg) on the 7th day. The results indicated that nilotinib significantly decreased APAP-induced elevation of biochemical markers (ALT, AST, ALP, LDH, ɤ GT, and total bilirubin). Additionally, nilotinib significantly increased hepatic GSH and SOD content, while decreased MDA content. Nil significantly suppressed the expression of HIF-1α and VEGF. Histopathological examination of hepatic tissue from Nil-treated mice revealed that Nil reduced acetaminophen-induced necrosis.

Smilax china L. Polysaccharide Alleviates Oxidative Stress and Protects From Acetaminophen-Induced Hepatotoxicity via Activating the Nrf2-ARE Pathway

The alleviation of oxidative stress is considered an effective treatment for acetaminophen (APAP)-induced acute liver injury (AILI). However, it remains unknow whether the potential antioxidant Smilax china L. polysaccharide (SCLP) protects against AILI. In this study, in vitro and in vivo experiments were conducted to verify the hepatoprotective effect of SCLP against AILI and explore the potential mechanism. We found that SCLP relieved liver histopathological changes; reversed the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), malondialdehyde (MDA) and reactive oxygen species (ROS); reversed the change in liver myeloperoxidase (MPO) activity; and enhanced liver antioxidant (GSH, GSH-Px, and t-SOD) levels in APAP-treated mice, thereby significantly reducing APAP-induced liver toxicity. SCLP rescued the cell viability and alleviated oxidative stress in H2O2-treated mouse AML12 (Alpha mouse liver 12) hepatocytes. The results of the mechanistic studies showed that SCLP upregulated nuclear factor E2 related factor (Nrf2) expression, promoted Nrf2 nuclear translocation, and enhanced the ability of Nrf2 to bind antioxidant response elements (AREs). Furthermore, SCLP activated Nrf2-ARE pathway, thus upregulating the expression of oxidative stress-related proteins heme oxygenase 1(HO-1), NAD(P)H quinone dehydrogenase 1(NQO-1) and glutamic acid cysteine ligase catalytic subunit (GCLC). In conclusion, this study confirmed the close correlation between liver protection by SCLP upon exposure to APAP and activated of the Nrf2-ARE pathway. These findings suggest that SCLP is an attractive therapeutic candidate drug for the treatment of AILI.

Actions of Klotho on hippocampal neuronal cells

Klotho gene was originally recognized as a putative aging-suppressor and its prominent age-regulating effects are mostly attributed to the modulation of mineral homeostasis in the kidney. However, recent studies link alterations in hippocampal Klotho expression with cognitive impairment and neurodegenerative diseases. This suggests that hippocampal neurons require Klotho for health and proper functionality. Klotho protects against neuronal dysfunction and regulates several intracellular signaling pathways including oxidative stress response, inflammation, DNA damage, autophagy, endoplasmic reticulum stress response, and multiple types of cell death. Specifically, this chapter covers the current knowledge as to how Klotho protein affects the hippocampal neuronal cells, with special attention paid to underlying molecular mechanisms, and thus influences hippocampal development, hippocampal-dependent cognition, behavior, and motor skills as well as mediates neurodegenerative processes.

Vitamin D deficiency exacerbates hepatic oxidative stress and inflammation during acetaminophen-induced acute liver injury in mice

Several experiments confirmed that vitamin D3 protected against acetaminophen (APAP)-induced acute liver injury (ALI). This research aimed to evaluate the influence of vitamin D deficiency (VDD) on APAP-induced ALI. In VDD and VDD + APAP groups, mice were fed with VDD diet. In APAP and VDD + APAP groups, mice were intraperitoneally injected with a sublethal dose of APAP (150 mg/kg). A sublethal dose of APAP caused a slight elevation of ALT and AST. Interestingly, APAP-induced elevation of ALT and AST was aggravated in VDD-fed mice. APAP-induced hepatic necrosis was exacerbated in VDD-fed mice. In addition, APAP-induced hepatocyte death, measured using TUNEL assay, was exacerbated in VDD-fed mice. Additional experiment showed that APAP-induced hepatic GSH depletion and lipid peroxidation were exacerbated in VDD-fed mice. Moreover, APAP-induced upregulation of antioxidant genes, such as hepatic heme oxygenase-1 (Ho-1), glutathione peroxidase (Gshpx), superoxide dismutase 1 (Sod1) and catalase enzymes (Cat), was aggravated in VDD-fed mice. Although a sublethal dose of APAP did not cause hepatic inflammation, hepatic proinflammatory cytokines and chemokines, such as Tnf-α, Kc, Mcp-1 and Mip2, were upregulated in VDD-fed mice treated with APAP. These results provide experimental data that VDD exacerbates hepatic oxidative stress and inflammation during APAP-induced ALI.

Nano-designed carbon monoxide donor SMA/CORM2 exhibits protective effect against acetaminophen induced liver injury through macrophage reprograming and promoting liver regeneration

Acetaminophen (APAP) induced liver injury is the most common drug-induced liver injury, accounting for the top cause of acute liver failure in the United State, however the therapeutic options for it is very limited. Excess generation of reactive oxygen species (ROS) and the subsequent inflammatory responses are the major factors of the liver injury. Carbon monoxide (CO) is an important gaseous molecule with versatile functions including anti-oxidation and anti-inflammation, and we previous reported the therapeutic potential of a nano-designed CO donor SMA/CORM2 in a dextran sulphate sodium (DSS) induced mouse colitis model. In this context, we investigated the effect of SMA/CORM2 in an APAP-induced mouse acute liver injury model and tackled the mechanisms involved. We found upregulation of heme oxygenase-1 (HO-1, endogenous CO generating enzyme) and the dynamic changes of macrophage polarization (pro-inflammatory M1/anti-inflammatory M2), which played important roles in the process of live injury. SMA/CORM2 treatment remarkably increased the CO levels in the liver and circulation, by which oxidative stresses in the liver were significantly reduced, and more importantly, it remarkably suppressed the expression of M1 macrophages but alternatively increased M2 polarization. Consequently the liver injury was significantly ameliorated, and the proliferation and regeneration were greatly promoted through the Pi3k/Akt/mTOR signaling pathway. The shift of macrophage polarization accompanied with the downregulated hypoxia-inducible factor-1α (HIF-1α) level. These findings suggested CO released from SMA/CORM2 manipulated the macrophage reprogramming toward M2 phenotype by inhibiting HIF-1α, which subsequently protected liver against inflammatory injury and benefited tissue repair. Moreover, compared to native CORM2, SMA/CORM2 exhibited superior bioavailability and protective effect. We thus anticipate the application of SMA/CORM2 as a therapeutic regimen for APAP induced liver injury as well as other inflammatory diseases and disorders.

Loss of GPR109A/HCAR2 induces aging-associated hepatic steatosis

GPR109A agonists have been used for the treatment of obesity however, the role of GPR109A in regulating aging-associated alterations in lipid metabolism is unknown. In this study we used Gpr109a^-/- mice to investigate the effect of aging in the regulation of lipid accumulation. We observed that in mouse and human livers, in addition to Kupffer cells, GPR109A is expressed in hepatocytes. Over 12 months, compared to wild type (WT), Gpr109a^-/- mice gained significantly more weight. Food intake and levels of serum lipids were similar among both groups. Compared to age-matched WT mice, 12-months old Gpr109a^-/- mice had significantly increased liver weight, hepatic steatosis and serum markers of liver injury. The fatty liver phenotype in Gpr109a^-/- mice was associated with increased hepatic expression of lipogenesis genes and decreased expression of lipolysis genes. Gpr109a^-/- mice had significantly increased fat tissues, which was associated with significant increase in adipocyte diameter and surface area. Adipose tissue from Gpr109a^-/- mice had increased expression of lipogenesis genes; however, expression of lipolytic genes was similar in both groups. Collectively, these results indicate that during aging, GPR109A modulates de novo lipid accumulation in liver and adipose tissue, and its dysregulation can lead to age-associated obesity and hepatic steatosis.

Group II muscarinic acetylcholine receptors attenuate hepatic injury via Nrf2/ARE pathway

Parasympathetic nervous system dysfunction is common in patients with liver disease. We have previously shown that muscarinic acetylcholine receptors (mAchRs) play an important role in the regulation of hepatic fibrosis and that the receptor agonists and antagonists affect hepatocyte proliferation. However, little is known about the impact of the different mAchR subtypes and associated signaling pathways on liver injury. Here, we treated the human liver cell line HL7702 with 10 mmol/L carbon tetrachloride (CCL4) to induce hepatocyte damage. We found that CCL4 treatment increased the protein levels of group I mAchRs (M1, M3, M5) but reduced the expression of group II mAchRs (M2, M4) and activated the Nrf2/ARE and MAPK signaling pathways. Although overexpression of M1, M3, or M5 led to hepatocyte damage with an intact Nrf2/ARE pathway, overexpression of M2 or M4 increased, and siRNA-mediated knockdown of either M2 or M4 decreased the protein levels of Nrf2 and its downstream target genes. Moreover, CCL4 treatment increased serum ALT levels more significantly, but only induced slight changes in the expression of mAchRs, NQO1 and HO1, while reducing the expression of M2 and M4 in liver tissues of Nrf2-/- mice compared to wild type mice. Our findings suggest that group II mAchRs, M2 and M4, activate the Nrf2/ARE signaling pathway, which regulates the expression of M2 and M4, to protect the liver from CCL4-induced injury.

Herbal Therapy for the Treatment of Acetaminophen-Associated Liver Injury: Recent Advances and Future Perspectives

Acetaminophen (APAP) overdose is the leading cause of drug-induced liver injury worldwide, and mitochondrial oxidative stress is considered the major event responsible for APAP-associated liver injury (ALI). Despite the identification of N-acetyl cysteine, a reactive oxygen species scavenger that is regarded as an effective clinical treatment, therapeutic effectiveness remains limited due to rapid disease progression and diagnosis at a late phase, which leads to the need to explore various therapeutic approaches. Since the early 1990s, a number of natural products and herbs have been found to have hepatoprotective effects against APAP-induced hepatotoxicity in terms of acute liver failure prevention and therapeutic amelioration of ALI. In this review, we summarize the hepatoprotective effects and mechanisms of medicinal plants, including herbs and fruit extracts, along with future perspectives that may provide guidance to improve the current status of herbal therapy against ALI.

M3 muscarinic receptor activation reduces hepatocyte lipid accumulation via CaMKKβ/AMPK pathway

Previously, we reported that hepatic muscarinic receptors modulate both acute and chronic liver injury, however, the role of muscarinic receptors in fatty liver disease is unclear. We observed in patients who underwent weight loss surgery, a decrease in hepatic expression of M3 muscarinic receptors (M3R). We also observed that fat loading of hepatocytes, increased M3R expression. Based on these observations, we tested the hypothesis that M3R regulate hepatocyte lipid accumulation. Incubation of AML12 hepatocytes with 1 mM oleic acid resulted in lipid accumulation that was significantly reduced by co-treatment with a muscarinic agonist (pilocarpine or carbachol), an effect blocked by atropine (a muscarinic antagonist). Similar treatment of Hepa 1-6 cells, a mouse hepatoblastoma cell line, showed comparable results. In both, control and fat-loaded AML12 cells, pilocarpine induced time-dependent AMPKα phosphorylation and significantly up-regulated lipolytic genes (ACOX1, CPT1, and PPARα). Compound C, a selective and reversible AMPK inhibitor, significantly blunted pilocarpine-mediated reduction of lipid accumulation and pilocarpine-mediated up-regulation of lipolytic genes. BAPTA-AM, a calcium chelator, and STO-609, a calcium/calmodulin-dependent protein kinase kinase inhibitor, attenuated agonist-induced AMPKα phosphorylation. Finally, M3R siRNA attenuated agonist-induced AMPKα phosphorylation as well as agonist-mediated reduction of hepatocyte steatosis. In conclusion, this proof-of-concept study demonstrates that M3R has protective effects against hepatocyte lipid accumulation by activating AMPK pathway and is a potential therapeutic target for non-alcoholic fatty liver disease.

Preventive action of benztropine on platinum-induced peripheral neuropathies and tumor growth

The endogenous cholinergic system plays a key role in neuronal cells, by suppressing neurite outgrowth and myelination and, in some cancer cells, favoring tumor growth. Platinum compounds are widely used as part of first line conventional cancer chemotherapy; their efficacy is however limited by peripheral neuropathy as a major side-effect. In a multiple sclerosis mouse model, benztropine, that also acts as an anti-histamine and a dopamine re-uptake inhibitor, induced the differentiation of oligodendrocytes through M1 and M3 muscarinic receptors and enhanced re-myelination. We have evaluated whether benztropine can increase anti-tumoral efficacy of oxaliplatin, while preventing its neurotoxicity.We showed that benztropine improves acute and chronic clinical symptoms of oxaliplatin-induced peripheral neuropathies in mice. Sensory alterations detected by electrophysiology in oxaliplatin-treated mice were consistent with a decreased nerve conduction velocity and membrane hyperexcitability due to alterations in the density and/or functioning of both sodium and potassium channels, confirmed by action potential analysis from ex-vivo cultures of mouse dorsal root ganglion sensory neurons using whole-cell patch-clamp. These alterations were all prevented by benztropine. In oxaliplatin-treated mice, MBP expression, confocal and electronic microscopy of the sciatic nerves revealed a demyelination and confirmed the alteration of the myelinated axons morphology when compared to animals injected with oxaliplatin plus benztropine. Benztropine also prevented the decrease in neuronal density in the paws of mice injected with oxaliplatin. The neuroprotection conferred by benztropine against chemotherapeutic drugs was associated with a lower expression of inflammatory cytokines and extended to diabetic-induced peripheral neuropathy in mice.Mice receiving benztropine alone presented a lower tumor growth when compared to untreated animals and synergized the anti-tumoral effect of oxaliplatin, a phenomenon explained at least in part by benztropine-induced ROS imbalance in tumor cells.This report shows that blocking muscarinic receptors with benztropine prevents peripheral neuropathies and increases the therapeutic index of oxaliplatin. These results can be rapidly transposable to patients as benztropine is currently indicated in Parkinson's disease in the United States.

Carbon monoxide releasing molecule A-1 attenuates acetaminophen-mediated hepatotoxicity and improves survival of mice by induction of Nrf2 and related genes

Acute liver injury is frequently associated with oxidative stress. Here, we investigated the therapeutic potential of carbon monoxide releasing molecule A-1 (CORM A-1) in oxidative stress-mediated liver injury. Overnight-fasted mice were injected with acetaminophen (APAP; 300 mg/kg; intraperitoneally) and were sacrificed at 4 and 12 h. They showed elevated levels of serum transaminases, depleted hepatic glutathione (GSH) and hepatocyte necrosis. Mice injected with CORM A-1 (20 mg/kg) 1 h after APAP administration, had reduced serum transaminases, preserved hepatic GSH and reduced hepatocyte necrosis. Mice that received a lethal dose of APAP (600 mg/kg), died by 10 h; but those co-treated with CORM A-1 showed a 50% survival. Compared to APAP-treated mice, livers from those co-treated with CORM A-1, had upregulation of Nrf2 and ARE genes (HO-1, GCLM and NQO-1). APAP-treated mice had elevated hepatic mRNA levels of inflammatory genes (Nf-κB, TNF-α, IL1-β and IL-6), an effect blunted in those co-treated with CORM A-1. In tert-butyl hydroperoxide (t-BHP)-treated HepG2 cells, CORM A-1 augmented cell viability, reduced oxidative stress, activated the nuclear factor erythroid 2-related factor 2 (Nrf2) and anti-oxidant response element (ARE) genes. The molecular docking profile of CO in the kelch domain of Keap1 protein suggested that CO released from CORM A-1 mediated Nrf2 activation. Collectively, these data indicate that CORM A-1 reduces oxidative stress by upregulating Nrf2 and related genes, and restoring hepatic GSH, to reduce hepatocyte necrosis and thus minimize liver injury that contributes to an overall improved survival rate.

Mechanisms of acetaminophen-induced liver injury and its implications for therapeutic interventions

Acetaminophen (APAP) overdose is the leading cause of drug-induced acute liver failure in many developed countries. Mitochondrial oxidative stress is considered to be the predominant cellular event in APAP-induced liver injury. Accordingly, N-acetyl cysteine, a known scavenger of reactive oxygen species (ROS), is recommended as an effective clinical antidote against APAP-induced acute liver injury (AILI) when it is given at an early phase; however, the narrow therapeutic window limits its use. Hence, the development of novel therapeutic approaches that can offer broadly protective effects against AILI is clearly needed. To this end, it is necessary to better understand the mechanisms of APAP hepatotoxicity. Up to now, in addition to mitochondrial oxidative stress, many other cellular processes, including phase I/phase II metabolism, endoplasmic reticulum stress, autophagy, sterile inflammation, microcirculatory dysfunction, and liver regeneration, have been identified to be involved in the pathogenesis of AILI, providing new targets for developing more effective therapeutic interventions against APAP-induced liver injury. In this review, we summarize intracellular and extracellular events involved in APAP hepatotoxicity, along with emphatic discussions on the possible therapeutic approaches targeting these different cellular events.

Seabuckthorn berry polysaccharide extracts protect against acetaminophen induced hepatotoxicity in mice via activating the Nrf-2/HO-1-SOD-2 signaling pathway

BACKGROUND

Oxidative stress is concomitant with acetaminophen (APAP)-induced hepatotoxicity, which has been highlighted as therapeutic targets for such diseases. The berries of Seabuckthorn (Hippophae rhamnoides L.) have been traditionally used in Tibetan medicine for thousands of years. The effect of Seabuckthorn berry polysaccharide on drug- induced liver injury (DILI) has not yet been elucidated.

PURPOSE

This study aims to investigate the protective effects and mechanisms of Seabuckthorn polysaccharide (SP) against APAP-induced hepatotoxicity.

STUDY DESIGN

Sixty C57BL/6 mice were randomly divided into six groups (n = 10 per group), namely the control group (Ctrl), APAP-induced-liver injury group (APAP), NAC pretreated group (NAC), 100 mg/kg SP pretreated group (APAP/SP100), 200 mg/kg SP pretreated group (APAP/SP200) and 200 mg/kg SP pretreated group without APAP challenge (SP200). SP was given orally to mice for 30 consecutive days prior to APAP exposure (300 mg/kg). NAC (150 mg/kg) was administrated 1 h before APAP challenge.

METHODS

ALT and AST were detected 16 h after APAP treatment; Hepatic expression of GSH, SOD, NO, iNOS and GSH-Px were examined. The expression of p-JNK, Bcl-2/Bax, p62, Keap-1 and SOD-2 was detected by Western blotting. The expression of Nrf-2 and its target genes HO-1, GCLC and NQO-1 were analyzed by RT-PCR and Western blotting.

RESULTS

Pretreatment with SP led to decreased levels of ALT and AST in APAP mice, without affecting APAP metabolism. This was accompanied by diminished liver injuries, increased levels of GSH and GSH-Px, reduced NO and iNOS expression. SP increased the activity of SOD as well as SOD-2 expression in APAP mice. SP suppressed APAP-induced JNK phosphorylation and increased the ratio of Bcl-2/Bax. Furthermore, SP decreased the expression of Keap-1 and increased the nuclear expression of Nrf-2. The expression of Nrf-2 target gene HO-1 was increased by SP pretreatment in APAP mice.

CONCLUSION

SP alleviates APAP-induced hepatotoxicity. The protective effects of SP are associated with the activation of the Nrf-2/HO-1-SOD-2 signaling pathway.

Mitochondrial involvement in memory impairment induced by scopolamine in rats

OBJECTIVE

Scopolamine (SCO) administration to rats induces molecular features of AD and other dementias, including impaired cognition, increased oxidative stress, and imbalanced cholinergic transmission. Although mitochondrial dysfunction is involved in different types of dementias, its role in cognitive impairment induced by SCO has not been well elucidated. The aim of this work was to evaluate the in vivo effect of SCO on different brain mitochondrial parameters in rats to explore its neurotoxic mechanisms of action.

METHODS

Saline (Control) or SCO (1 mg/kg) was administered intraperitoneally 30 min prior to neurobehavioral and biochemical evaluations. Novel object recognition and Y-maze paradigms were used to evaluate the impact on memory, while redox profiles in different brain regions and the acetylcholinesterase (AChE) activity of the whole brain were assessed to elucidate the amnesic mechanism of SCO. Finally, the effects of SCO on brain mitochondria were evaluated both ex vivo and in vitro, the latter to determine whether SCO could directly interfere with mitochondrial function.

RESULTS

SCO administration induced memory deficit, increased oxidative stress, and increased AChE activities in the hippocampus and prefrontal cortex. Isolated brain mitochondria from rats administered with SCO were more vulnerable to mitochondrial swelling, membrane potential dissipation, H₂O₂ generation and calcium efflux, all likely resulting from oxidative damage. The in vitro mitochondrial assays suggest that SCO did not affect the organelle function directly.

CONCLUSION

In conclusion, the present results indicate that SCO induced cognitive dysfunction and oxidative stress may involve brain mitochondrial impairment, an important target for new neuroprotective compounds against AD and other dementias.

Progressive changes in detrusor function and micturition patterns with chronic bladder ischemia

Purpose

Lower urinary tract symptoms (LUTS) are bothersome constellation of voiding symptoms in men and women as they age. Multiple factors and comorbidities are attributed to this problem but underlying mechanisms of nonobstructive nonneurogenic detrusor overactivity, detrusor underactivity and LUTS remain largely unknown. Our goal was to characterize detrusor function and voiding patterns in relation to muscarinic receptors expression, nerve fiber density, and neural ultrastructure in chronic bladder ischemia.

Materials and Methods

Iliac artery atherosclerosis and bladder ischemia were produced in male Sprague-Dawley rats. At 8 and 16 weeks after ischemia, micturition patterns and cystometrograms were recorded in conscious rats then bladder blood flow and nonvoiding spontaneous contractions were measured under general anesthesia. Bladder tissues were processed for Western blotting, immunostaining, and transmission electron microscopy.

Results

Bladder responses to ischemic insult depended on the duration of ischemia. Micturition patterns and cystometric changes at 8-week ischemia suggested detrusor overactivity, while voiding behavior and cystometrograms at 16-week ischemia implied abnormal detrusor function resembling underactivity. Upregulation of muscarinic M2 receptor was found after 8- and 16 weeks of ischemia. Downregulation of M3 and upregulation of M1 were detected at 16-week ischemia. Neural structural damage and marked neurodegeneration were found after 8 and 16 weeks of ischemia, respectively.

Conclusions

Prolonged ischemia may be a mediating variable in progression of overactive bladder to dysfunctional patterns similar to detrusor underactivity. The mechanism appears to involve differential expression of M1, M2, and M3 receptors, neural structural injury, and progressive loss of nerve fibers.

Salvianolic Acid B Prevents Iodinated Contrast Media-Induced Acute Renal Injury in Rats via the PI3K/Akt/Nrf2 Pathway

Contrast-induced acute renal injury (CI-AKI) has become a common cause of hospital-acquired renal failure. However, the development of prophylaxis strategies and approved therapies for CI-AKI is limited. Salvianolic acid B (SB) can treat cardiovascular-related diseases. The aim of the present study was to assess the effect of SB on prevention of CI-AKI and explore its underlying mechanisms. We examined its effectiveness of preventing renal injury in a novel CI-AKI rat model. Compared with saline, intravenous SB pretreatment significantly attenuated elevations in serum creatinine and the histological changes of renal tubular injuries, reduced the number of apoptosis-positive tubular cells, activated Nrf2, and lowered the levels of renal oxidative stress induced by iodinated contrast media. The above renoprotection of SB was abolished by the PI3K inhibitor (wortmannin). In HK-2 cells, SB activated Nrf2 and decreased the levels of oxidative stress induced by hydrogen peroxide and subsequently improved cell viability. The above cytoprotection of SB was blocked by the PI3K inhibitor (wortmannin) or siNrf2. Thus, our results demonstrate that, due to its antioxidant properties, SB has the potential to effectively prevent CI-AKI via the PI3K/Akt/Nrf2 pathway.

Data regarding M1 muscarinic receptor-mediated modulation of hepatic catalase activity in response to oxidative stress

We recently demonstrated the role of M1 muscarinic receptors (M1R) in modulating oxidative stress in liver and hepatocytes (Urrunaga et al., 2015) [1]. Here we provide data regarding the effect of a novel M1R agonist, VU0357017 (Lebois et al., 2010) [2], on H₂O₂-mediated hepatocyte injury, the effect of an M1R antagonist VU0255035 (Sheffler et al., 2009) [3] on catalase and super oxide dismutase (SOD) activities in H₂O₂–treated hepatocytes in vitro, and finally, the effect of M1R ablation on hepatic catalase activity in acetaminophen (APAP)-treated mice.

M1 Muscarinic Receptor Deficiency Attenuates Azoxymethane-Induced Chronic Liver Injury in Mice

Cholinergic nervous system regulates liver injury. However, the role of M1 muscarinic receptors (M1R) in modulating chronic liver injury is uncertain. To address this gap in knowledge we treated M1R-deficient and WT mice with azoxymethane (AOM) for six weeks and assessed liver injury responses 14 weeks after the last dose of AOM. Compared to AOM-treated WT mice, M1R-deficient mice had attenuated liver nodularity, fibrosis and ductular proliferation, α-SMA staining, and expression of α1 collagen, Tgfβ-R, Pdgf-R, Mmp-2, Timp-1 and Timp-2. In hepatocytes, these findings were associated with reductions of cleaved caspase-3 staining and Tnf-α expression. In response to AOM treatment, M1R-deficient mice mounted a vigorous anti-oxidant response by upregulating Gclc and Nqo1 expression, and attenuating peroxynitrite generation. M1R-deficient mouse livers had increased expression of Trail-R2, a promotor of stellate cell apoptosis; dual staining for TUNNEL and α-SMA revealed increased stellate cells apoptosis in livers from M1R-deficient mice compared to those from WT. Finally, pharmacological inhibition of M1R reduced H₂O₂-induced hepatocyte apoptosis in vitro. These results indicate that following liver injury, anti-oxidant response in M1R-deficient mice attenuates hepatocyte apoptosis and reduces stellate cell activation, thereby diminishing fibrosis. Therefore, targeting M1R expression and activation in chronic liver injury may provide therapeutic benefit.

Withaferin-A Reduces Acetaminophen-Induced Liver Injury in Mice

Withaferin-A (WA) has anti-oxidant activities however, its therapeutic potential in acetaminophen (APAP) hepatotoxicity is unknown. We performed a proof-of-concept study to assess the therapeutic potential of WA in a mouse model that mimics APAP-induced liver injury (AILI) in humans. Overnight fasted C57BL/6NTac (5-6 wk. old) male mice received 200 mg/kg APAP intraperitoneally (i.p.). After 1 h mice were treated with 40 mg/kg WA or vehicle i.p., and euthanized 4 and 16 h later; their livers were harvested and serum collected for analysis. At 4 h, compared to vehicle-treated mice, WA-treated mice had reduced serum ALT levels, hepatocyte necrosis and intrahepatic hemorrhage. All APAP-treated mice had reduced hepatic glutathione (GSH) levels however, reduction in GSH was lower in WA-treated when compared to vehicle-treated mice. Compared to vehicle-treated mice, livers from WA-treated mice had reduced APAP-induced JNK activation, mitochondrial Bax translocation, and nitrotyrosine generation. Compared to vehicle-treated mice, WA-treated mice had increased hepatic up-regulation of Nrf2, Gclc and Nqo1, and down-regulation of Il-6 and Il-1β. The hepatoprotective effect of WA persisted at 16 h. Compared to vehicle-treated mice, WA-treated mice had reduced hepatocyte necrosis and hepatic expression of Il-6, Tnf-α and Il-1β, increased hepatic Gclc and Nqo1 expression and GSH levels, and reduced lipid peroxidation. Finally, in AML12 hepatocytes, WA reduced H₂O₂-induced oxidative stress and necrosis by preventing GSH depletion. Collectively, these data show mechanisms whereby WA reduces necrotic hepatocyte injury, and demonstrate that WA has therapeutic potential in AILI.

Pathophysiological significance of c-jun N-terminal kinase in acetaminophen hepatotoxicity

BACKGROUND

Acetaminophen (APAP) overdose is the leading cause of acute liver failure in the US. Although substantial progress regarding the mechanisms of APAP hepatotoxicity has been made in the past several decades, therapeutic options are still limited and novel treatments are clearly needed. c-jun N-terminal Kinase (JNK) has emerged as a promising therapeutic target in recent years.

AREAS COVERED

Early studies established the critical role of JNK activation and mitochondrial translocation in APAP hepatotoxicity. However, this concept has also been challenged. Initial studies failed to reproduce the protection of JNK deficiency in APAP toxicity and concerns over off-target effects of JNK inhibitors and even in knock-out mice are increasing. Interestingly, recent studies have even shown that liver injury can be altered with or without effects on JNK activation. The current review addresses these discrepancies and tries to explain or reconcile some of the conflicting results.

EXPERT OPINION

JNK is a potential therapeutic target for APAP poisoning. However, controversies still exist regarding its actual role in APAP hepatotoxicity. Future studies are warranted for more in-depth testing of specific inhibitors in well-defined preclinical models and human hepatocytes before JNK can be considered a relevant therapeutic target for APAP poisoning.