Enhanced Xenobiotic-Induced Hepatotoxicity and Kupffer Cell Activation by Restraint-Induced Stress

Progress of depression mechanism based on Omics method

Depression is a very common disabling mental disorder, which is typically characterized by high rates of disability and mortality. Although research into the various mechanisms of depression was still underway, its physiopathology remains uncertain. The rapid developments in new technologies and the combined use of a variety of techniques will help to understand the pathogenesis of depression and explore effective treatment methods. In this review, we focus on the combination of proteomic and metabolomic approaches to analyze metabolites and proteins in animal models of depression induced by different modeling approaches, with the aim of broadening the understanding of the physiopathological mechanisms of depression using complementary "omics" strategy.

Geraniol activates Nrf-2/HO-1 signaling pathway mediating protection against oxidative stress-induced apoptosis in hepatic ischemia-reperfusion injury

Geraniol (GOH) is a natural essential oil that possesses antioxidant, anti-inflammatory, and antiapoptotic properties by various signaling pathways. Liver ischemia-reperfusion injury (IRI) is a serious event that triggers liver dysfunction or even failure. Nuclear factor erythroid 2-related factor 2 (Nrf2), a transcriptional factor, maintains cellular defense mechanism through antioxidant and anti-inflammatory properties. To detect GOH effect against liver IRI through the activation of the Nrf2/HO-1 antioxidant pathway, five groups of rats were randomized to normal, sham, IR, GOH, and GOH/IR. Blood samples and liver tissues were collected to measure various biochemical parameters related to liver function, and oxidative stress as well as inflammatory and apoptotic indicators besides liver tissue histopathology was evaluated by light microscopy. GOH induces activation of Nrf2 along with the upregulation of HO-1 expression. Also, the antioxidant activity of GOH was shown by the elevation of total antioxidant capacity and GSH levels, together with normalizing malondialdehyde. Regarding the anti-inflammatory effect of GOH, it suppresses the levels of TNF-α, iNOS, and COX-2. Additionally, the antiapoptotic effect of GOH, Bax, and caspase-3, 9 were reduced in liver tissue. GOH is a promising hepatoprotective agent in liver IRI through the activation of Nrf2/HO-1 antioxidant pathway.

Proteomic Analysis of Liver Proteins in a Rat Model of Chronic Restraint Stress-Induced Depression

Depression is a global mental disorder disease and greatly threatened human health and stress is considered to be one of the important factors that lead to depression. In this study, we used newly developed iTRAQ labeling and high performance liquid chromatography (HPLC) and mass spectrum united analysis technology obtained the 2176 accurate proteins. Successively, we used the GO analysis and IPA software to analyze the 98 differentially expressed proteins of liver in depression rats due to chronic restraint stress, showing a map of proteomics analysis of liver proteins from the aspects of related functions, disease and function analysis, canonical pathway analysis, and associated network. This study provide important information for comprehensively understanding the mechanisms of dysfunction or injury in the liver in depression.

Hepatoprotective activity of viscosine is mediated by attenuation of hepatic macrophages and iNOS expression in CCl4-intoxicated rats

This study investigated the molecular mechanism(s) of the protective effects of a C-alkylated flavonoid, viscosine on an animal model of CCl₄-induced hepatotoxicity. Viscosine at 20, 50 and 100 mg kg^-1 was orally administered in a dose dependent manner per day for 3 days before the CCl₄ (1 : 1 v/v in olive oil, 1 ml kg^-1) treatment and 2 days after the treatment. Hepatoprotection was assessed in terms of reduction in serum enzyme activities (ALT, AST, and ALP) that occur after CCl₄ injury, and by histopathology and immunohistochemistry. The rise in serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) in CCl₄-intoxicated rats was markedly suppressed by viscosine in a concentration dependent manner. The decrease in the activity of hepatic antioxidant enzyme, SOD, was significantly prevented by viscosine, likewise gradually the levels of MDA and GSH were also normalized compared to silymarin. Viscosine also reduced the CCl₄-induced damaged area from 2% to 0% as assessed by histopathology and prevented the mixed inflammatory infiltrate. Viscosine attenuated the inflammation in the liver around the injured central vein region by downregulating the CCl₄ induced activation of hepatic CD68+ macrophages, thereby reducing their number as well. The expression of inducible nitric oxide synthase (iNOS) was more potentially suppressed by viscosine compared to the FDA approved positive control silymarin. The results of this study indicate that viscosine could be effective in protecting the liver from acute CCl₄-induced injury. The hepatoprotective mechanisms of viscosine may be related to the free radical scavenging and attenuation of oxidative stress, as well as to the inhibition of inflammatory response in the liver. Here, we are proposing a novel mechanism of action of viscosine and suggesting that it may be a safe and better in vivo antioxidant.

Chronic restraint stress reduces carbon tetrachloride-induced liver fibrosis

Stress as a cofactor has been reported to affect the progression and severity of liver diseases. The present study investigated the effect of chronic restraint stress on carbon tetrachloride (CCl₄)-induced liver fibrosis. A total of 30 male BALB/c mice were randomly divided into three groups: Oil-treated control group; CCl₄-treated group; and CCl₄ + restraint-treated group. CCl₄ was administrated via intraperitoneal injection once every 3 days over a period of 42 days. In the CCl₄ + restraint-treated group, mice were immobilized using 50 ml centrifuge tubes for 0.5 h to inflict chronic restraint stress immediately after the injection of CCl₄. On day 42, blood and liver tissue samples were collected for analysis. The effect of restraint on CCl₄-induced liver fibrosis in mice was evaluated by analyzing the serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Histopathological examination of liver samples was performed using hematoxylin and eosin (HE), Masson's trichrome, 5-hydroxytryptamine 2B (5-HT2B) receptor and α-smooth muscle actin (α-SMA) immumohistochemical staining. ALT, AST, 5-HT2B receptor and α-SMA expression levels were significantly increased in mice exposed to CCl₄ in comparison with those in the oil-treated control mice (P<0.01). However, these increases were significantly reduced by exposure to restraint (P<0.05). HE and Masson's trichrome staining revealed that restraint can alleviate CCl₄-induced liver fibrosis. These results suggest that chronic restraint stress reduces the development of liver fibrosis by inhibiting the activation of hepatic stellate cells via 5-HT2B receptor. Therefore, restraint may be a useful therapeutic approach in the management of liver fibrosis.

Extracellular ATP induces P2X7 receptor activation in mouse Kupffer cells, leading to release of IL-1β, HMGB1, and PGE2, decreased MHC class I expression and necrotic cell death

Kupffer cells, which are resident macrophages in liver, can produce various cytokines and chemokines that induce hepatitis and liver fibrosis. It is suggested that extracellular ATP-induced activation of macrophage P2X7 receptor plays an important role in inflammation via release of pro-inflammatory mediators, but the role of P2X7 receptor in Kupffer cells remains unclear. Here, we show that activation of P2X7 receptor in Kupffer cells causes multiple inflammatory responses, using the clonal mouse Kupffer cell line (KUP5) that we previously established. Treatment of LPS-primed Kupffer cells with 3 mM ATP induced Ca(2+) influx, non-selective large pore formation, activation of MAPK, cell lysis, IL-1β release, prostaglandin E2 (PGE2) release, high mobility group box1 (HMGB1) release, and major histocompatibility complex (MHC) class I shedding. These events were significantly suppressed by pretreatment with P2X7 antagonist A438079, indicating involvement of P2X7 receptor activation in these inflammatory responses. Our results suggest that extracellular ATP-induced activation of P2X7 receptor of Kupffer cells plays multiple roles in the inflammatory response in liver. P2X7 receptor might be a new therapeutic target for treatment of liver diseases.

The role of alpha-1 and alpha-2 adrenoceptors in restraint stress-induced liver injury in mice

Acute stress affects cellular integrity in many tissues including the liver, but its underlying mechanism is still unclear. The aim of the present study was to investigate the potential involvement of catecholamines and adrenoceptors in the regulation of acute restraint stress-induced liver injury. Restraint was achieved by placing mice in restraint tubes. Mice were treated with either an α-l antagonist, prazosin, an α-2 antagonist, yohimbine, a β-l antagonist, betaxolol, a β-2 antagonist, ICI 118551, or a central and peripheral catecholamine depleting agent, reserpine, and followed by restraint stress. Assessment of liver injury (serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) , hepatic total GSH, GSSG and GSH/GSSG ratio) , histopathology and of apoptosis, by TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling) assay and western blotting, was performed. Three hours of restraint stress resulted in liver injury, as indexed by elevated serum transaminase levels, decreased hepatic total GSH levels and GSH/GSSG ratio, increased hepatic GSSG levels as well as enhanced hepatocytes apoptosis. Either reserpine or prazosin or yohimbine was found to attenuate liver injury. Furthermore, prazosin and yohimbine protected against restraint-induced hepatocytes apoptosis through attenuating the activation of caspases-9 and -3 and reducing the Bax/Bcl-2 ratio. These results suggest that α-1 and α-2 adrenoceptors mediate restraint-induced liver oxidative injury through caspase-9 and Bcl-2 family of apoptotic regulatory proteins.

Aqueous date fruit extract protects against lipid peroxidation and improves antioxidant status in the liver of rats subchronically exposed to trichloroacetic acid

Trichloroacetic acid (TCA) is a prominent by-product of the chlorination of drinking water. It induces cell damage by producing free radicals and reactive oxygen species. The present study was carried out to evaluate the potential hepatoprotective role of the aqueous date extract (ADE) against TCA-induced liver injury. Forty-eight male Wistar rats were randomly divided into six groups of eight: group I served as the control; group II was given ADE by gavage; groups III and IV received TCA as drinking water at 0.5 and 2 g/L, respectively; and groups V and VI were treated with ADE by gavage and then received TCA at 0.5 and 2 g/L, respectively, as drinking water. The experiment was performed for 2 months. The hepatotoxicity of TCA administration was revealed by an increase in the levels of hepatic marker enzymes (transaminases, gamma-glutamyl transferase, and lactate dehydrogenase) and conjugated bilirubin and a decrease in albumin level. The TCA administration induced also significant elevation of the malondialdehyde (MDA) level and the antioxidant activity of superoxide dismutase (SOD) and glutathione peroxidase (GPx) paralleled with a significant decline in catalase (CAT) activity. These biochemical alterations were accompanied by histological changes marked by the appearance of vacuolization, necrosis, congestion, inflammation, and enlargement of sinusoids in the liver section. Treatment with date palm fruit extract restored the liver damage induced by TCA, as demonstrated by inhibition of hepatic lipid peroxidation; amelioration of SOD, GPx, and CAT activities; and improvement of histopathology changes. These results suggest that ADE has a protective effect over TCA-induced oxidative damage in rat liver.

Submandibular salivary glands: influence on growth rate and life span in mice

Submandibular glands accumulate a variety of growth factors, especially in male mice. Surgical excision of these glands (sialoadenectomy) results in alterations in several organs and systems including the liver, skin and reproductive system. We studied the life-long consequences of sialoadenectomy in male mice. Animals were operated at the age of 10 weeks. Thereafter, body weight and food and water intake were controlled until death. Few weeks after surgery, body weight was lower in sialoadenectomized than in control mice. The difference remained stable until the age of 80 weeks. In spite of the lower body weight, food intake was higher in sialoadenectomized mice than in controls. The first death of sialoadenectomized mice occurred 10 weeks earlier than that of the first control, and the initial death rate in sialoadenectomized mice was almost twice the rate in controls. After 100 weeks of life, the death rate increased in control mice, but suddenly decreased in sialoadenectomized mice. The consequence was that the mean life span of the last 25% surviving animals was 10 weeks longer in sialoadenectomized than in control mice. Autopsy examination suggests that the effect of sialoadenectomy on death rate may be the consequence of a contrasting effect on tumour growth. Our results indicate that submandibular glands, or rather the factors derived from these glands, have contrasting roles in tumour growth. At early ages they may be survival factors and protect tissues, whereas at later ages they may stimulate the growth of transformed cells.

Pathologic role of stressed-induced glucocorticoids in drug-induced liver injury in mice

We previously reported that acetaminophen (APAP)-induced liver injury (AILI) in mice is associated with a rise in serum levels of the glucocorticoid (GC), corticosterone. In the current study, we provide evidence that endogenous GC play a pathologic role in AILI. Specifically, pretreatment of mice with the GC receptor (GCR) inhibitor, RU486 (mifepristrone), protected normal but not adrenalectomized mice from AILI, while pretreatment with dexamethasone, a synthetic GC, exacerbated AILI. RU486 did not affect the depletion of whole liver reduced GSH or the formation of APAP-protein adducts. It also had no effects on the formation of reactive oxygen species or the depletion of mitochondrial GSH or ATP. While RU486 pretreatment also protected against halothane-induced liver injury, it exacerbated concanavalin A (ConA)- and carbon tetrachloride (CCl(4))-induced liver injury, demonstrating the complexity of GC effects in different types of liver injury.

CONCLUSION

These results suggest that under certain conditions, elevated levels of GC might represent a previously unappreciated risk factor for liver injury caused by APAP and other drugs through the diverse biological processes regulated by GCR.

Adrenaline stimulates H2O2generation in liver via NADPH oxidase

It is known that adrenaline promotes hydroxyl radical generation in isolated rat hepatocytes. The aim of this work was to investigate a potential role of NADPH oxidase (Nox) isoforms for an oxidative stress signal in response to adrenaline in hepatocytes. Enriched plasma membranes from isolated rat liver cells were prepared for this purpose. These membranes showed catalytic activity of Nox isoforms, probably Nox 2 based on its complete inhibition with specific antibodies. NADPH was oxidized to convert O(2) into superoxide radical, later transformed into H(2)O(2). This enzymatic activity requires previous activation with either 3 mM Mn(2+) or guanosine 5'-0-(3-thiotriphosphate) (GTPgammaS) plus adrenaline. Experimental conditions for activation and catalytic steps were set up: ATP was not required; S(0.5) for NADPH was 44 microM; S(0.5) for FAD was 8 microM; NADH up to 1 mM was not substrate, and diphenyleneiodonium was inhibitory. Activation with GTPgammaS plus adrenaline was dose- and Ca(2+)-dependent and proceeded through alpha(1)-adrenergic receptors (AR), whereas beta-AR stimulation resulted in inhibition of Nox activity. These results lead us to propose H(2)O(2) as additional transduction signal for adrenaline response in hepatic cells.

Effect of allyl alcohol on hepatic transporter expression: zonal patterns of expression and role of Kupffer cell function

During APAP toxicity, activation of Kupffer cells is critical for protection from hepatotoxicity and up-regulation of multidrug resistance-associated protein 4 (Mrp4) in centrilobular hepatocytes. The present study was performed to determine the expression profile of uptake and efflux transporters in mouse liver following treatment with allyl alcohol (AlOH), a periportal hepatotoxicant. This study also investigated the role of Kupffer cells in AlOH hepatotoxicity, and whether changes in transport protein expression by AlOH are dependent on the presence of Kupffer cells. C57BL/6J mice received 0.1 ml clodronate liposomes to deplete Kupffer cells or empty liposomes 48 h prior to dosing with 60 mg/kg AlOH, i.p. Hepatotoxicity was assessed by plasma ALT and histopathology. Hepatic transporter mRNA and protein expression were determined by branched DNA signal amplification assay and Western blotting, respectively. Depletion of Kupffer cells by liposomal clodronate treatment resulted in heightened susceptibility to AlOH toxicity. Exposure to AlOH increased mRNA levels of several Mrp genes, while decreasing organic anion transporting polypeptides (Oatps) mRNA expression. Protein analysis mirrored many of these mRNA changes. The presence of Kupffer cells was not required for the observed changes in uptake and efflux transporters induced by AlOH. Immunofluorescent analysis revealed enhanced Mrp4 staining exclusively in centrilobular hepatocytes of AlOH treated mice. These findings demonstrate that Kupffer cells are protective from AlOH toxicity and that induction of Mrp4 occurs in liver regions away from areas of AlOH damage independent of Kupffer cell function. These results suggest that Kupffer cell mediators do not play a role in mediating centrilobular Mrp4 induction in response to periportal damage by AlOH.

Depletion of liver glutathione levels in rats: a potential confound of nose-only inhalation

Nose-only inhalation exposure chambers offer key advantages to whole-body systems, particularly when aerosol or mixed aerosol-vapor exposures are used. Specifically, nose-only chambers provide enhanced control over the route of exposure and dose by minimizing the deposition of particles either on the subjects skin/fur or on surfaces of a whole-body exposure system. In the current series of experiments, liver, brain, and lung total glutathione (GSH) levels were assessed following either nose-only or whole-body exposures to either jet fuel or to clean, filtered air. The data were compared to untreated control subjects. Acute nose-only inhalation exposures of rats resulted in a significant depletion of liver GSH levels both in subjects that were exposed to clean, filtered air as well as those exposed to JP-8 jet fuel and to a synthetic jet fuel. Glutathione levels were not altered in lung or brain tissue. Whole-body inhalation exposure had no effect on GSH levels in any tissue for any of the treatment groups. A second experiment demonstrated that the loss of GSH did not occur if rats were anaesthetized prior to and during nose-only exposure to clean, filtered air or to mixed hydrocarbons. These data appear to be consistent with studies demonstrating depletion in liver GSH levels among rats subjected to restraint stress. Finally, the depletion of GSH that was observed in liver following a single acute exposure was reduced following five daily exposures to clean, filtered air, suggesting the possibility of habituation to restraint in the nose-only exposure chamber. The finding that placement in a nose-only exposure chamber per se yields liver GSH depletion raises the possibility of an interaction between this mode of toxicant exposure and the toxicological effects of certain inhaled test substances.

Association between physical restraint and drug-induced liver injury

OBJECTIVE

As animal models have suggested enhancement of xenobiotic-induced hepatotoxicity due to restraint stress, a case-control study was undertaken to investigate the effects of physical restraint on the development of drug-induced liver injury (DILI) in a psychiatric intensive care unit.

METHOD

Demographic and clinical characteristics were compared between restrained patients (n = 106) and nonrestrained patients (n = 528) admitted to the psychiatric intensive care unit during a 4-year period from January 2003 to December 2006.

RESULTS

Rates of DILI differed significantly between restrained patients (8.5%) and nonrestrained patients (1.9%; odds ratio 4.81, p = 0.0016), although no initial differences were seen in medical and psychiatric conditions. No differences in mean number of drugs were identified. The rate of patients who received antipsychotics was higher in the restrained group than in the nonrestrained group, whereas the rate of patients who received antidepressants was higher in the nonrestrained group than in the restrained group.

CONCLUSIONS

Despite methodological limitations imposed by the retrospective design, a conservative claim can be made that physical restraint might represent a risk for DILI. This observation deserves confirmation in a prospective study.

Liver injury after an aggressive encounter in male mice

Acute and intense psychological stressors induce cell damage in several organs, including the heart and the liver. Much less is known about social stress. In male mice, aggressive behavior is the most common social stressor. It is remarkable that upon fighting, submandibular salivary glands release a number of peptides into the bloodstream including epidermal growth factor (EGF). We showed previously that released EGF protects the heart from cell damage in this particular stressful situation. Here, we studied the effect of an aggressive encounter on the liver and whether EGF has a similar effect on this organ. An aggressive encounter in male mice caused inflammatory response and a transient increase in plasma alanine and aspartate transaminase activities. At 3 h, focal infiltration of neutrophils was observed in liver parenchyma. These cells accumulate on eosinophilic hepatocytes, which may correspond to dying cells. A few hours later, evidence of necrotic lesion was observed. Surgical excision of submandibular glands, sialoadenectomy, did not prevent the rise in plasma EGF concentration and did not affect the increase in plasma transaminase activities. Neither did the administration of tyrphostin AG-1478 (inhibitor of EGF receptor kinase) alter the increase in plasma alanine transaminase activity. However, it did enhance the rise in both aspartate transaminase and creatine kinase activity, suggesting heart damage. We conclude that an aggressive encounter causes mild liver damage and that released EGF does not protect this organ, in contrast to its effect on the heart.