Electric foot shock stress-induced exacerbation of alpha-galactosylceramide-triggered apoptosis in mouse liver

Brain-gut-liver axis: Chronic psychological stress promotes liver injury and fibrosis via gut in rats

Background

The effect of chronic psychological stress on hepatitis and liver fibrosis is concerned. However, its mechanism remains unclear. We investigated the effect and mechanism of chronic psychological stress in promoting liver injury and fibrosis through gut.

Methods

Sixty male SD rats were randomly assigned to 6 groups. Rat models of chronic psychological stress (4 weeks) and liver fibrosis (8 weeks) were established. The diversity of gut microbiota in intestinal feces, permeability of intestinal mucosa, pathologies of intestinal and liver tissues, collagen fibers, protein expressions of toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), nuclear factor kappa β (NF-κβ), tumor necrosis factor α (TNF-α) and interleukin 1 (IL-1) in liver tissue, liver function and coagulation function in blood and lipopolysaccharide (LPS) in portal vein blood were detected and analyzed.

Results

The diversities and abundances of gut microbiota were significant differences in rats among each group. The pathological lesions of intestinal and liver tissues, decreased expression of occludin protein in intestinal mucosa, deposition of collagen fibers and increased protein expression of TLR4, MyD88, NF-κβ, TNF-α and IL-1 in liver tissue, increased LPS level in portal vein blood, and abnormalities of liver function and coagulation function, were observed in rats exposed to chronic psychological stress or liver fibrosis. There were significant differences with normal rats. When the dual intervention factors of chronic psychological stress and liver fibrosis were superimposed, the above indicators were further aggravated.

Conclusion

Chronic psychological stress promotes liver injury and fibrosis, depending on changes in the diversity of gut microbiota and increased intestinal permeability caused by psychological stress, LPS that enters liver and acts on TLR4, and active LPS-TLR4 pathway depend on MyD88. It demonstrates the possibility of existence of brain-gut-liver axis.

Prevalence of subclinical bactibilia in apparently healthy shelter dogs

OBJECTIVES

To determine the prevalence of subclinical bactibilia in apparently healthy shelter dogs and characterise serum liver enzymes activities, hepatobiliary histopathology and bile cytology in apparently healthy dogs with and without bactibilia.

MATERIALS AND METHODS

Healthy, abandoned dogs euthanased for non-medical reasons were prospectively recruited for this cross-sectional study. Whole blood, collected immediately before euthanasia, was submitted for serum liver enzyme activity (alkaline phosphatase, alanine aminotransferase and gamma-glutamyl transferase) analyses. Bile, gall bladder and liver samples were collected aseptically from dogs within 25 minutes of euthanasia. Bile was submitted for bacterial culture and cytology in all dogs. Gall bladder and liver samples were submitted for histopathological examination in bactibilic dogs and nine randomly selected non-bactibilic dogs.

RESULTS

Sixty-five healthy dogs were included in this study. Bactibilia was diagnosed in 10.8% (7/65) of dogs, with 9.2% (6/65) of dogs diagnosed on cytological examination and 4.6% (3/65) on culture. Elevated alanine aminotransferase activities were present in one bactibilic and five non-bactibilic dogs; and elevated gamma-glutamyl transferase activities in one bactibilic and two non-bactibilic dogs. No dogs had elevated alkaline phosphatase activities. Histopathological changes in bactibilic and non-bactibilic dogs included lymphoplasmocellular cholecystitis (7/7 and 9/9), gall bladder oedema (7/7 and 9/9), hepatic vacuolar degeneration (6/7 and 8/9), cholangitis (5/7 and 7/9), hepatic nodular hyperplasia (3/7 and 5/9) and hepatic cholestasis (2/7 and 4/9).

CLINICAL SIGNIFICANCE

This study confirms that subclinical bactibilia occurs in a small number of apparently healthy shelter dogs and that subclinical hepatobiliary histopathological abnormalities can occur in apparently healthy bactibilic and non-bactibilic dogs.

Acceleration of TAA-Induced Liver Fibrosis by Stress Exposure Is Associated with Upregulation of Nerve Growth Factor and Glycopattern Deviations

Liver fibrosis results from many chronic injuries and may often progress to cirrhosis and hepatocellular carcinoma (HCC). In fact, up to 90% of HCC arise in a cirrhotic liver. Conversely, stress is implicated in liver damage, worsening disease outcome. Hence, stress could play a role in disrupting liver homeostasis, a concept that has not been fully explored. Here, in a murine model of TAA-induced liver fibrosis we identified nerve growth factor (NGF) to be a crucial regulator of the stress-induced fibrogenesis signaling pathway as it activates its receptor p75 neurotrophin receptor (p75NTR), increasing liver damage. Additionally, blocking the NGF decreased liver fibrosis whereas treatment with recombinant NGF accelerated the fibrotic process to a similar extent than stress challenge. We further show that the fibrogenesis induced by stress is characterized by specific changes in the hepatoglycocode (increased β1,6GlcNAc-branched complex N-glycans and decreased core 1 O-glycans expression) which are also observed in patients with advanced fibrosis compared to patients with a low level of fibrosis. Our study facilitates an understanding of stress-induced liver injury and identify NGF signaling pathway in early stages of the disease, which contributes to the established fibrogenesis.

An Herbal Formula CGplus Ameliorates Stress-Induced Hepatic Injury in a BALB/c Mouse Model

INTRODUCTION

Stress is a well-known factor for inflammation in diverse organs/tissues. Stress also leads to liver injury, which was supported by clinical observations and animal studies. We herein investigated the hepatoprotective property of an herbal formula (called as CGplus) consisting of Artemisia gmelinii Weber ex Stechm. (syn, Artemisia iwayomogi Kitamura), Wurfbainia villosa var. xanthioides (Wall. ex Baker) Skornick. & A.D.Poulsen (syn, Amomum xanthioides Wallich), and Salvia miltiorrhiza Bunge against stress-induced hepatic damage.

METHODS

Male BALB/c mice were orally administered water extract of CGplus (0, 50, 100, or 200 mg/kg) daily for 5 days, and then subjected to immobilization stress for 6 h on the 5th day.

RESULTS

Acute immobilization stress elevated remarkably serum concentrations of stress hormones (corticosterone and adrenaline) and two hepatic injury parameters (ALT and AST), while these alterations were significantly attenuated by the administration of CGplus. The increases of oxidative parameters (ROS, NO, lipid peroxidation, and protein carbonyl) and deviation of IL-1β and IL-10 in opposite directions in hepatic tissues were significantly normalized by CGplus. Pre-treatment with CGplus also notably ameliorated the abnormal activation of toll-like receptor 4 (TLR4), CD14, and lipopolysaccharide-binding protein (LPB) as well as infiltration of neutrophils in hepatic tissues.

CONCLUSION

These results suggest that an herbal formula (CGplus) derived from traditional pharmaceutical theory has a potent protective effect against stress-induced hepatic injury via regulation of pro- (IL-1β) and anti-inflammatory (IL-10) cytokines.

Investigating the role of nitric oxide in stress adaptive process in electric foot shock stress-subjected mice

AIM

The present study was designed to investigate the role of nitric oxide (NO) in the non-development of stress adaptation in high-intensity foot-shock stress (HIFS) subjected mice.

METHODS

Mice were subjected to low-intensity shocks (LIFS i.e. 0.5 mA) or HIFS (1.5 mA) for 5 days. Stress-induced behavioral changes were assessed by actophotometer, hole board, open field and social interaction tests. Biochemically, the serum corticosterone levels were measured as a marker of stress. L-arginine (100 mg/kg and 300 mg/kg), as NO donor, and L-NAME (10 mg/kg and 30 mg/kg), as nitric oxide synthase (NOS) inhibitor, were employed as pharmacological agents.

RESULTS

A single exposure of LIFS and HIFS produced behavioral and biochemical alterations. However, there was the restoration of behavioral and biochemical alterations on 5^th day in response to repeated LIFS exposure suggesting the development of stress adaptation. However, no stress adaptation was observed in HIFS subjected mice. Administration of L-arginine (300 mg/kg) abolished the stress adaptive response in LIFS-subjected mice, while L-NAME (30 mg/kg) induced the development of stress adaptation in HIFS subjected mice.

CONCLUSION

It is concluded that an increase in the NO release may possibly impede the process of stress adaptation in HIFS-subjected mice.

Depressive-like behaviors are induced by chronic liver injury in male and female mice

Depression is a highly prevalent mental disease and increasingly become a global public health problem. Recent studies have shown that the dysfunction of liver was associated with depression. However, the previous studies have not been fully explained the relationship between depression and liver injury. The present study was aimed to investigate whether chronic liver injury could induce depressive-like behavior. Chronic liver injury was induced by intraperitoneal injection of carbon (CCl₄), D-galactosamine (D-GalN) and thioacetamide (TAA), respectively. And the results showed that the serum activities of ALT in CCl₄, D-GalN and TAA groups were significantly increased in both male and female mice compared with the control group, while the activities of AST increased only in CCl₄ group. Meanwhile, H&E staining showed that CCl₄, D-GalN and TAA induced hepatocytes injury in both male and female mice. Moreover, the sucrose preference was significantly decreased and the immobility time in forced swimming test and tail suspension test were significantly prolonged in CCl₄ and D-GalN group compared with control group. Our findings demonstrated that chronic liver injury induced by CCl₄ and D-GalN could induce depressive-like behaviors in mice.

Effect of Selank on Morphological Parameters of Rat Liver in Chronic Foot-Shock Stress

We studied the effects of Selank on morphological parameters of the liver in Wistar male rats subjected to chronic foot-shock stress. Selank was injected intraperitoneally in doses of 100, 300 and 1000 μg/kg 15 min before each stress session. Morphological and morphometrical analysis showed that chronic foot-shock stress induced hydropic degeneration of hepatocytes, an increase of the nucleus/cytoplasm ratio due to an increase in the area of nuclei and reduction of the cytoplasm area, the appearance of focal necroses, and lymphohistiocyte infiltration. Injection of Selank in all doses reduced the intensity of stress-induced degenerative changes. Administration of Selank in doses of 300 and 1000 μg/kg restored the nucleus/cytoplasm ratio in hepatocytes. The maximum stress-limiting effect was attained after administration of 300 μg/kg Selank.

Chronic Psychosocial Stress in Mice Is Associated With Increased Acid Sphingomyelinase Activity in Liver and Serum and With Hepatic C16:0-Ceramide Accumulation

Chronic psychosocial stress adversely affects human morbidity and is a risk factor for inflammatory disorders, liver diseases, obesity, metabolic syndrome, and major depressive disorder (MDD). In recent studies, we found an association of MDD with an increase of acid sphingomyelinase (ASM) activity. Thus, we asked whether chronic psychosocial stress as a detrimental factor contributing to the emergence of MDD would also affect ASM activity and sphingolipid (SL) metabolism. To induce chronic psychosocial stress in male mice we employed the chronic subordinate colony housing (CSC) paradigm and compared them to non-stressed single housed control (SHC) mice. We determined Asm activity in liver and serum, hepatic SL concentrations as well as hepatic mRNA expression of genes involved in SL metabolism. We found that hepatic Asm activity was increased by 28% (P = 0.006) and secretory Asm activity by 47% (P = 0.002) in stressed mice. C16:0-Cer was increased by 40% (P = 0.008). Gene expression analysis further revealed an increased expression of tumor necrosis factor (TNF)-α (P = 0.009) and of several genes involved in SL metabolism (Cers5, P = 0.028; Cers6, P = 0.045; Gba, P = 0.049; Gba2, P = 0.030; Ormdl2, P = 0.034; Smpdl3B; P = 0.013). Our data thus provides first evidence that chronic psychosocial stress, at least in mice, induces alterations in SL metabolism, which in turn might be involved in mediating the adverse health effects of chronic psychosocial stress and peripheral changes occurring in mood disorders.

Effect of Selank on Functional State of Rat Hepatocytes under Conditions of Restraint Stress

We studied the effect of Selank administered intraperitoneally in doses of 100, 300, and 1000 μg/kg to male Wistar rats 15 min prior to restraint stress on the content of aminotransferases and total protein concentration in blood serum and intensity of free radical oxidation in the liver. Under conditions of acute restraint stress, Selank in doses of 100 and 300 μg/kg decreased catalase and superoxide dismutase activities and malondialdehyde concentration and increased total antioxidant activity in the liver homogenate. Administration of Selank in a dose of 1000 μg/kg reduced the content of aminotransferases in blood serum, decreased superoxide dismutase activity in the liver, and increased total antioxidant activity. Under conditions of chronic stress, Selank in all doses produced similar effects: reduced superoxide dismutase activity and malondialdehyde concentration in the liver tissue and AST activity in the serum. The other parameters remained unchanged.

Inhibition of emotional needs and emotional wellbeing predict disease progression of chronic hepatitis C patients: an 8-year prospective study

Background

The role of psycosocial factors in the disease progression of chronic hepatitis C (CHC) patients remains unclear. The aim of the present study was to prospectively evaluate the prognostic value of behavioral patterns and the quality of life (QOL) of patients with CHC.

Methods

Two hundred and forty Japanese CHC patients (mean age 62.4 years) were assessed for behavioral patterns (Stress Inventory), QOL (Functional Assessment of Chronic Illness Therapy-Spiritual), and known prognostic factors at baseline then followed for a maximum of 8 years for disease progression, defined as either the first diagnosis of hepatocellular carcinoma (HCC) or hepatitis-related death.

Results

Forty-nine events occurred during the study period (46 newly diagnosed HCC cases, three hepatitis-related deaths). In a Cox proportional hazard model including known prognostic factors and treatment-related factors as time-dependent variables, behavioral patterns associated with inhibition of emotional needs (hazard ratio (HR): 1.35; 95 % confidence interval (CI): 1.02–1.77; p = 0.036) and QOL, representing emotional wellbeing (HR 0.60; 95 % CI 0.37–0.98; p = 0.041), were each associated with the risk of disease progression.

Conclusion

Psychosocial factors such as behavioral patterns relevant to the inhibition of emotional needs and emotional wellbeing independently affect the clinical course of patients with CHC.

Electronic supplementary material

The online version of this article (doi:10.1186/s13030-016-0075-3) contains supplementary material, which is available to authorized users.

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.

Psychological stress exerts effects on pathogenesis of hepatitis B via type-1/type-2 cytokines shift toward type-2 cytokine response

BACKGROUND

Psychological and physical stress has been demonstrated to have an impact on health through modulation of immune function. Despite high prevalence of stress among patients with hepatitis B virus (HBV) infection, little is known about whether and how stress exerts an effect on the course of hepatitis B.

METHODS

Eighty patients with chronic hepatitis B(CHB) completed the Perceived Stress Scale-10(PSS-10) and State-Trait Anxiety Inventory(STAI). Fresh whole blood was subject to flow cytometry for lymphocytes count. Plasma samples frozen at -80 °C were thawed for cytokines, alanine aminotransferase (ALT), and virus load. These patients were grouped into high or low perceived stress, state anxiety and trait anxiety groups according to the scale score. Sociodemographic, disease-specific characteristics, lymphocytes count and cytokines were compared.

RESULTS

Firstly, a negative association between ALT and stress (t =  -4.308; p =  .000), state anxiety (t =  -3.085; p =  .003) and trait anxiety (t =  -4.925; p =  .000) were found. As ALT is a surrogate marker of hepatocytes injury, and liver injury is a consequence of immune responses. Next, we tested the relationship between stress/anxiety and lymphocytes. No statistical significance were found with respect to counts of total T cells, CD4+ T cell, CD8+ T cell, NK cell, and B cell count between high and low stress group. Type-2 cytokine interleukin-10 (IL-10) level was significantly higher in high stress group relative to lower counterpart (t = 6.538; p = 0.000), and type-1 cytokine interferon-gamma (IFN-γ) level shown a decreased tendency in high stress group (t =  -1.702; p = 0.093). Finally, INF-γ:IL-10 ratio displayed significant decrease in high perceived stress(t =  -4.606; p = 0.000), state anxiety(t =  -5.126; p = 0.000) and trait anxiety(t =  -4.670; p = 0.000) groups relative to low counterparts.

CONCLUSION

Our data show stress is not related to the lymphocyte cells count in CHB patients, however, stress induces a shift in the type-1/type-2 cytokine balance towards a type-2 response, which implicated a role of psychological stress in the course of HBV related immune-pathogenesis.

The antinociceptive effect of dexmedetomidine modulates spleen cell immunity in mice

BACKGROUND

Pain plays roles in both the nervous system and immune system. Changes in the neuroendocrine pathway under pain conditions give rise to sympathetic outflow with increased plasma catecholamines and activate immune reactions. Dexmedetomidine exerts sedative, analgesic, and anesthetic-sparing effects and is known to diminish pro-inflammatory processes by central sympatholytic effects. To investigate the influence of the analgesic effect of dexmedetomidine on immunomodulation under pain conditions, splenic natural killer (NK) tumoricidal cytotoxic activity, proliferative ability of T lymphocytes, and cytokine changes were assessed.

METHODS

After evaluation of the analgesic efficacy of dexmedetomidine in C57BL mice that were subjected to formalin-induced pain, dexmedetomidine (30 µg/kg) or saline was injected intraperitoneally (ip) 30 min before formalin (20 µL of 2% formalin in 0.9% saline) injection. NK cell activity against NK-sensitive YAC-1 lymphoma cells was evaluated by the percentage of specific lactate dehydrogenase (LDH) release. Various numbers of effector cells (NK cells) were added to the wells of a microtiter plate containing 2 × 10(4) target YAC-1 cells in 100 μL, to achieve final effector-to-target cell ratios of 80:1, 40:1, and 20:1. The level of lymphocyte proliferation in response to phytohemagglutinin (PHA) was detected by bromodeoxyuridine (BrdU) incorporation assay. TNF-α, IL-1β, and IL-10 levels were determined in blood samples and supernatants of splenocyte preparations.

RESULTS

IP administration of dexmedetomidine significantly decreased the time of licking and biting during the first and second phases of the formalin test (p <0.001). Formalin-induced pain led to higher activity of NK cells than in sham-treated mice (p <0.05), but NK activity was not increased significantly by ip dexmedetomidine treatment. Formalin-induced pain significantly increased splenic lymphocyte proliferation (p <0.05), but dexmedetomidine did not alter this response. There was a significant increase in plasma TNF-α (p = 0.048) and IL-6 (p = 0.014) levels after formalin-induced pain. However, the differences between the responses after ip dexmedetomidine did not change significantly.

CONCLUSIONS

Dexmedetomidine showed antinociceptive effect on both of acute pain phase 1 and hyperalgesic phase 2 of formalin pain model. Formalin-induced pain alters cellular immunity of spleen in mice. Dexmedetomidine attenuates the activation of NK cells under pain condition, but neither the proliferative response of the splenic lymphocytes nor the cytokine production was affected by dexmedetomidine.

The role of anesthetic drugs in liver apoptosis

CONTEXT

The modern practice of anesthesia is highly dependent ona group of anesthetic drugs which many of them are metabolized in the liver.

EVIDENCE ACQUISITION

The liver, of course, usually tolerates this burden. However, this is not always an unbroken rule. Anesthetic induced apoptosis has gained great concern during the last years; especially considering the neurologic system.

RESULTS

However, we have evidence that there is some concern regarding their effects on the liver cells. Fortunately not all the anesthetics are blamed and even some could be used safely, based on the available evidence.

CONCLUSIONS

Besides, there are some novel agents, yet under research, which could affect the future of anesthetic agents' fate regarding their hepatic effects.

Interpreting Stress Responses during Routine Toxicity Studies

Stress often occurs during toxicity studies. The perception of sensory stimuli as stressful primarily results in catecholamine release and activation of the hypothalamic–pituitary–adrenal (HPA) axis to increase serum glucocorticoid concentrations. Downstream effects of these neuroendocrine signals may include decreased total body weights or body weight gain; food consumption and activity; altered organ weights (e.g., thymus, spleen, adrenal); lymphocyte depletion in thymus and spleen; altered circulating leukocyte counts (e.g., increased neutrophils with decreased lymphocytes and eosinophils); and altered reproductive functions. Typically, only some of these findings occur in a given study. Stress responses should be interpreted as secondary (indirect) rather than primary (direct) test article–related findings. Determining whether effects are the result of stress requires a weight-of-evidence approach. The evaluation and interpretation of routinely collected data (standard in-life, clinical pathology, and anatomic pathology endpoints) are appropriate and generally sufficient to assess whether or not changes are secondary to stress. The impact of possible stress-induced effects on data interpretation can partially be mitigated by toxicity study designs that use appropriate control groups (e.g., cohorts treated with vehicle and subjected to the same procedures as those dosed with test article), housing that minimizes isolation and offers environmental enrichment, and experimental procedures that minimize stress and sampling and analytical bias.

This article is a comprehensive overview of the biological aspects of the stress response, beginning with a Summary (Section 1) and an Introduction (Section 2) that describes the historical and conventional methods used to characterize acute and chronic stress responses. These sections are followed by reviews of the primary systems and parameters that regulate and/or are influenced by stress, with an emphasis on parameters evaluated in toxicity studies: In-life Procedures (Section 3), Nervous System (Section 4), Endocrine System (Section 5), Reproductive System (Section 6), Clinical Pathology (Section 7), and Immune System (Section 8). The paper concludes (Section 9) with a brief discussion on Minimizing Stress-Related Effects (9.1.), and a final section explaining why Parameters routinely measured are appropriate for assessing the role of stress in toxicology studies (9.2.).

Lasting consequences of traumatic events on behavioral and skeletal parameters in a mouse model for post-traumatic stress disorder (PTSD)

BACKGROUND

Post-traumatic stress disorder (PTSD) is an anxiety disorder that not only affects mental health, but may also affect bone health. However, there have been no studies to examine the direct relationship between PTSD and bone.

METHODOLOGY/PRINCIPAL FINDINGS

We employed electric shocks in mice to simulate traumatic events that cause PTSD. We also injected the anxiogenic drug FG-7142 prior to electric shocks. Electric shocks created lasting conditioned fear memory in all mice. In young mice, electric shocks elicited not only behavioral response but also skeletal response, and injection of FG-7142 appeared to increase both types of response. For example in behavioral response within the first week, mice shocked alone froze an average of 6.2 sec in 10 sec tests, and mice injected with FG-7142 froze 7.6 sec, both significantly different (P<0.05) from control mice, which only froze 1.3 sec. In skeletal response at week 2, shocks alone reduced 6% bone mineral content (BMC) in total body (P = 0.06), while shocks with FG-7142 injection reduced not only 11% BMC (P<0.05) but also 6% bone mineral density (BMD) (P<0.05). In addition, FG-7142 injection also caused significant reductions of BMC in specific bones such as femur, lumbar vertebra, and tibia at week 3. Strong negative correlations (R(2) = -0.56, P<0.05) and regression (y = 0.2527-0.0037 * x, P<0.01) between freezing behavior and total body BMC in young mice indicated that increased contextual PTSD-like behavior was associated with reduced bone mass acquisition.

CONCLUSIONS/SIGNIFICANCE

This is the first study to document evidence that traumatic events induce lasting consequences on both behavior and skeletal growth, and electric shocks coupled with injection of anxiogenic FG-7142 in young mice can be used as a model to study the effect of PTSD-like symptoms on bone development.

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.

Psychosocial stress and liver disease status

"Psychosocial stress" is an increasingly common concept in the challenging and highly-demanding modern society of today. Organic response to stress implicates two major components of the stress system, namely the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system. Stress is anamnestically reported by patients during the course of disease, usually accompanied by a decline in their overall health status. As the mechanisms involving glucocorticoids and catecholamines have been deciphered, and their actions on immune cell function deeper understood, it has become clear that stress has an impact on hepatic inflammatory response. An increasing number of articles have approached the link between psychosocial stress and the negative evolution of hepatic diseases. This article reviews a number of studies on both human populations and animal models performed in recent years, all linking stress, mainly of psychosocial nature, and the evolution of three important liver-related pathological entities: viral hepatitis, cirrhosis and hepatocellular carcinoma.

Apolipoprotein E-mediated immune regulation in sepsis

Lipids and lipoproteins have emerged as key constituents of the immune response to microbial infection. We, therefore, sought to understand the complex interaction between lipoprotein metabolism and sepsis. Apolipoprotein E (apoE), a component of plasma lipoproteins, has been suggested to bind and traffic Ags for NKT cell activation. However, apoE's role in sepsis has not been demonstrated. In this study, we examined the effect of exogenous apoE in a rat model of septic peritonitis, induced by cecal ligation and puncture. We demonstrate that 48 h after serial injections of apoE, septic mortality increased in a dose-dependent manner. While sepsis resulted in increased splenic and decreased hepatic and circulating NKT cell populations, serial injections of apoE for 24 h after cecal ligation and puncture increased the frequency, cell number, and BrdU uptake in splenic and hepatic NKT cell populations, while concomitantly depleting these populations in the circulation. These changes were correlated with elevated alanine amino transferase levels, an indicator of liver injury. Interestingly, while sepsis increased hepatic T cell apoptosis and necrosis, apoE reversed these changes. apoE also promoted increases in predominantly Th1 cytokine levels in sera and a decrease in IL-4, the main NKT cell-derived Th2 cytokine. Consequently, apoE treatment is associated with increased sepsis-induced mortality, and increased NKT cell frequency and proliferation in the liver and spleen, with concomitant decreases in these NKT cell parameters in the peripheral circulation. apoE treatment also promoted a Th1 cytokine response, increased the degree of liver injury, and decreased apoptosis in hepatic lymphocytes.

The hepatic vagus nerve attenuates Fas-induced apoptosis in the mouse liver via alpha7 nicotinic acetylcholine receptor

BACKGROUND & AIMS

Although accumulating evidence has recently shown that the efferent vagus nerve attenuates systemic inflammation, it remains unclear whether or not the vagus nerve can affect Fas-induced liver apoptosis. We investigated the effect of the vagus nerve by using a selective hepatic vagotomy.

METHODS

We assessed the mortality and apoptosis in Fas-induced fulminant hepatitis in sham-operated and vagotomized male C57BL/6 mice. To determine how the nerve influences hepatocyte apoptosis, hepatitis was preceded by pretreatment with nicotine; PNU-282987, an alpha7 nicotinic acetylcholine receptor (AChR) agonist; liposome-encapsulated dichloromethylene diphosphonate (lipo-Cl(2)MDP), a macrophage eliminator; and Mn (III) tetrakis (4-benzoic acid) porphyrin chloride (MnTBAP), an oxidative inhibitor.

RESULTS

Mortality in the vagotomized mice was significantly higher than that in the sham-operated mice following intravenous administration with the anti-Fas antibody Jo-2. This result was also supported by the data from both terminal deoxynucleotidyl-transferase mediated dUTP nick-end labeling and caspase-3 assay, in which vagotomized livers showed a significant elevation in the number of apoptotic hepatocytes and increased caspase-3 activity following Jo-2 treatment compared with the sham-operated livers. Supplementation with nicotine and PNU-282987 dose dependently inhibited this detrimental effect of the vagotomy. Moreover, the vagotomy-triggered exacerbation of Fas-induced hepatitis was completely blocked by lipo-Cl(2)MDP. Similarly, pretreatment with MnTBAP also completely suppressed the vagotomy-triggered exacerbation.

CONCLUSIONS

The hepatic vagus nerve appears to play an important role in attenuating Fas-induced hepatocyte apoptosis through alpha7 nicotinic AChR, perhaps by causing the Kupffer cells to reduce their generation of an excessive amount of reactive oxygen species.

Effect of acute pain on splenic NK cell activity, lymphocyte proliferation and cytokine production activities

Various types of physical and physiological stress in animals have been shown to affect their humoral and cell-mediated immune responses. The present study was designed to investigate the possible influence of acute pain on the immune system. BALB/c mice were exposed to an increasing number of heat shocks using a Tail Flick apparatus; an equal number of control mice received no shock treatments. After each of the regimens was completed, the spleen of each mouse was recovered and various cell populations isolated to assess: the proliferative response to phytohemagglutinin by lymphocytes; cytotoxic activities of natural killer (NK) cells; and, the production of select important cytokines by splenic lymphocytes. The results indicated that NK cell activity and proliferation of lymphocytes were significantly (p < 0.001) increased due to the shock regimens after only a single day's rounds of stimulation (i.e., 3 rounds of approximately 12 equally time-spaced shocks/hr with 30-45 min gap between rounds). After 2 and 3 days' rounds of stimulations, no significant changes were detected in the proliferative response of isolated lymphocytes; conversely, the activity of NK cells remained significantly elevated compared to the controls hosts' cells, even on the second day of stimulation but not on the third. Regarding effects on cytokines, no significant changes were detected in the amount of Interferon-gamma (IFNgamma) and Interlukin-10 (IL-10) produced by lymphocytes obtained from the spleens of any of the shocked mice. These results could suggest that certain acute stressors might actually strengthen a host's immunological reactivity and, possibly, result in an enhanced capacity to resist pathogens that might infect the body.

Immunohistochemical analysis of hepatic ganglioside distribution following a partial hepatectomy and exposure to different hyperbaric oxygen treatments

Ganglioside GM3(Neu5Ac) expression is highly increased in liver 54h following 15% partial hepatectomy in pre-operatively oxygenated rats. GM3(Neu5Gc), GM2, GalNAc-GM1b and gangliosides of the neolacto-series are less affected. GM3(Neu5Ac) is a potent inhibitor of epidermal growth factor signaling. Since GM3(Neu5Ac) growth inhibitory effect depends on its cellular localization, the aim of this study was to detect ganglioside cellular localization during liver regeneration. The experiment was performed using the same rat model which previously showed increased ganglioside expression and more efficient liver regeneration. Frozen sections of liver were analyzed using confocal microscopy after labeling for binding of five ganglioside-specific antibodies, with or without hepatocyte membrane permeabilization. Ganglioside precursors, ceramide (Cer), monohexaosylceramide and lactosylceramide (LacCer) were determined by high-performance thin-layer chromatography. Apoptosis was assessed by fluorescein-dUTP end-labeling of fragmented DNA. Liver of pre-operative oxygenated rats showed high perinuclear labeling of GM3(Neu5Ac) which was absent in post-operative oxygenated and control animals. In the same group, Cer content was lower, monohexaosylceramide and LacCer were absent, and content of apoptotic cells was significantly the lowest, compared to other groups examined (F=20.36, p=0.0001). These findings indicate that ganglioside GM3(Neu5Ac) may be involved in mediation of beneficial effects of pre-operatively oxygenation during the liver regeneration.

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.

Early-life psychological stress exacerbates adult mouse asthma via the hypothalamus-pituitary-adrenal axis

RATIONALE

Despite accumulating evidence that psychological stress has a short-lasting detrimental effect on asthma, little is known about the way stress in childhood predisposes to adult asthma.

OBJECTIVES

Using a communication box, we investigated the long-lasting effect of early psychological and physical stress on adult asthma in mice.

METHODS

Male BALB/c mice were exposed to either psychological stress or physical stress three times (every other day) during their fourth week of life. The mice were sensitized to ovalbumin at 8 and 10 weeks, and an ovalbumin airway challenge was conducted at the age of 11 weeks.

RESULTS

Twenty-four hours after ovalbumin challenge, both psychological and physical stress-exposed mice exhibited a significant acceleration in the number of total mononuclear cells and eosinophils and airway hyperresponsiveness compared with control mice. No differences in serum anti-OVA-specific immunoglobulin E levels were found between stress-exposed and control animals after antigen sensitization. In the psychological stress group, but not in the physical stress group, an elevation of the serum corticosterone levels during ovalbumin challenge was significantly attenuated in comparison with the control group. Moreover, pretreatment with RU-486, a glucocorticoid receptor antagonist, before ovalbumin challenge completely inhibited a psychological stress-induced exacerbation of asthma. However, pretreatment with GR-82334, a neurokinin-1 receptor antagonist, failed to affect physical stress-induced augmentation of airway inflammation.

CONCLUSION

Early psychological and physical stresses aggravated adult asthma via hyporesponsiveness of the hypothalamic-pituitary-adrenal axis during antigen challenge and via a pathway(s) distinct from the hypothalamic-pituitary-adrenal axis or neurokinin-1 receptors.

Deletion of the SOCS3 gene in liver parenchymal cells promotes hepatitis-induced hepatocarcinogenesis

BACKGROUND & AIMS

A recent study has suggested that the methylation silencing of the suppressor of cytokine signaling-3 (SOCS3), a negative regulator of interleukin-6-related cytokines, could be involved in hepatocellular carcinoma (HCC). However, the roles of SOCS3 in hepatocellular carcinogenesis and hepatitis have not been established. We investigated the effect of deleting the SOCS3 gene on the development of hepatitis and HCC in hepatitis C virus-infected patients and mouse models.

METHODS

The expression of SOCS genes in HCC and non-HCC regions of patient samples was determined by real-time reverse-transcription polymerase chain reaction and immunoblotting. The conditional knockout approach in mice was used to determine the hepatocyte-specific roles of SOCS3. To generate a liver-specific deletion, floxed SOCS3 (SOCS3(fl/fl)) mice were crossed with albumin-Cre transgenic mice. Hepatitis and HCC were induced by administering concanavalin A and diethylnitrosamine, respectively.

RESULTS

SOCS3 expression was reduced in the HCC regions compared with the non-HCC regions. Carcinogen-induced hepatic tumor development was enhanced by deletion of the SOCS3 gene, which was associated with higher levels of the targets of signal transducers and activators of transcription (ie, B-cell lymphoma-XL, B-cell lymphoma-2, C-myelocytomatosis, cyclin D1, and vascular endothelial growth factor). In the concanavalin A-mediated hepatitis model, deletion of the SOCS3 gene in the hepatocytes protected against liver injury through suppression of interferon-gamma signaling and induction of the antiapoptotic protein Bcl-XL.

CONCLUSIONS

Deletion of the SOCS3 gene in hepatocytes promotes the activation of STAT3, resistance to apoptosis, and an acceleration of proliferation, resulting in enhanced hepatitis-induced hepatocarcinogenesis.

Does stress exacerbate liver diseases?

Although anecdotal comments on detrimental effects of psychosocial stress on liver diseases can be found even in the early literature, only recently has scientific evidence been reported. The present article reviewed such evidence to demonstrate how stress exacerbates liver diseases. A search of the literature from the last two decades was performed using MEDLINE by pairing 'psychological stress' with 'liver' or 'hepatitis.' Additional research was conducted by screening the bibliographies of articles retrieved in the MEDLINE search. The search results showed that the principal effectors of the activated hypothalamic-pituitary-adrenal (HPA) axis, glucocorticoids, can exert a facilitative effect on the hepatic inflammatory response and even increase the risk of developing hepatocellular carcinoma. For certain liver diseases, defective HPA axis activation, which probably contributed to the exacerbation of the liver disease, has been reported. The efferent sympathetic/adrenomedullary system mainly contributes to the stress-induced exacerbation of liver diseases via its neurotransmitters, the catecholamines. In contrast, the efferent parasympathetic nervous system elicits an inhibitory effect on the development of hepatic inflammation. In conclusion, the pathophysiological interaction between stress and the liver appears to be regulated by the complex, dynamic networks of both the endocrine and autonomic nervous systems, which implies a further need for basic research into the involved mechanisms and for clinical evidence to apply psychosocial support to patients with chronic liver diseases.

Glycosphingolipids and mitochondria: role in apoptosis and disease

Glycosphingolipids (GSLs) comprise a class of lipids with important structural and signaling functions. Synthesized from ceramide in the Golgi, they are subsequently distributed to different compartments, most predominantly in the plasma membrane where they integrate signaling platforms. A recently characterized trafficking of ganglioside GD3 (GD3), a GSLs with two sialic-acid residues, to mitochondria has revealed a novel function of this lipid as a death effector. In addition to the interaction of GD3 with mitochondria recruiting these organelles to apoptotic pathways, GD3 disables survival paths dependent on NF-kappaB, thus favoring the balance towards cell death. The present review gathers the evidence documenting this emerging function of GSLs in cell death and their involvement in pathological states.

Social disruption stress exacerbates alpha-galactosylceramide-induced hepatitis in mice

OBJECTIVE

Psychosocial stress has been suggested as a possible aggravating factor in liver diseases, however, the underlying mechanism has yet to be clarified. Recently, our research revealed that electric foot-shock stress aggravated NK1.1 Ag(+) T cell-dependent alpha-galactosylceramide (alpha-GalCer)-induced hepatitis in mice via a mechanism mediated by endogenous glucocorticoids. In this study, we examined whether or not such aggravation could be applied to a psychosocially stressful situation, e.g. social disruption stress.

METHODS

Male wild-type C57BL/6 (B6) or B6 hepatitis virus type B surface antigen transgenic (HBs-tg) mice, a hepatitis B virus carrier mouse model, were exposed 3 times in 1 week to social disruption stress in which an 8-month-old aggressive male intruder was placed into their home cage (5 mice per group) for 2 h. Twelve hours after the final exposure to the stress, the wild-type and HBs-tg mice were intravenously injected with alpha-GalCer.

RESULTS

The stress-exposed wild-type mice exhibited significantly reduced thymus weight loss compared with the control animals. Moreover, this stress regimen led to a significant increase in serum alanine aminotransferase levels in both the wild-type and the HBs-tg mice, although the increase in the HBs-tg mice was higher than that in the wild-type mice.

CONCLUSION

These findings demonstrated that, similar to electric foot-shock stress, social disruption stress exacerbated alpha-GalCer-induced hepatitis.