Gadolinium chloride suppresses styrene-induced cytochrome P450s expression in rat liver.

To assess the effect of gadolinium (Gd) on the expression of several forms of cytochrome P450 (P450s) and antioxidant enzymes, we treated rats with gadolinium chloride (25 mg as Gd/kg body weight) 4 h after styrene (a multiple P450 inducer) treatment (600 mg/kg). Gd treatment significantly suppressed styrene-inducible cytochrome P4502B1 (CYP2B1), CYP2B2, CYP2E1, and CYP3A2 mRNA expressions to 48.6%, 69.8%, 61.1%, and 38.5%, accompanying with the reduction of proteins expression to 1.42%, 31.2%, 21.1% and 21.1%, respectively, compared with styrene alone treatment. Gd suppressed styrene-inducible CYP1A2 expression, but only at the protein level. On the other hand, styrene treatment caused a decrease in reduced form of glutathione (GSH), as well as increases in lipid peroxide and serum ALT and AST activities, suggesting the occurrence of hepatic damage probably due to styrene-induced oxidative stress in rat liver. Post-treatment of Gd attenuated this styrene-caused hepatic damage. Moreover, mRNA expressions of cellular antioxidant enzymes such as catalase, CuZn-superoxide dismutase (CuZnSOD) and glutathione peroxidase (GPX) were hardly changed by styrene and/or Gd treatment. In summary, Gd suppressed styrene-inducible expression of not only CYP2B1 but also several forms of P450 at both the mRNA and protein levels, along with attenuation of styrene-caused liver damage. These findings suggested that Gd is a chemo-preventive agent against hepatic damage caused by xenobiotics requiring biotransformation.

Rotavirus double-stranded RNA induces apoptosis and diminishes wound repair in rat intestinal epithelial cells.

BACKGROUND: Recent studies have shown that toll-like receptor 3 (TLR3) recognizes double-stranded RNA (dsRNA). Rotaviruses, having a dsRNA genome, infect intestinal epithelial cells (IEC) and cause acute gastroenteritis in young children. The aim of the present study was to clarify the pathophysiological function of rotavirus dsRNA in IEC. METHODS: Expression of TLR3 mRNA or protein in IEC cell lines (IEC-6, HT-29, Caco-2) was assessed by reverse transcription polymerase chain reaction (RT-PCR), Western blot analysis or immunohistochemistry. Induction of cytokines (TNF-alpha, interferon-beta, interleukin-6) mRNA and activation of signal proteins (ERK1/2 MAPK and IkappaB-alpha) in IEC after stimulation with rotavirus dsRNA were assessed by RT-PCR or Western blot analysis. IEC-6 cells were wounded and cell migration into wound areas after stimulation with rotavirus dsRNA (1-25 microg/mL) was assessed. Induction of apoptosis after stimulation with rotavirus dsRNA was also assessed. RESULTS: Expression of TLR3 mRNA and TLR3 protein was detected in IEC. Expression of TLR3 mRNA in IEC-6 tended to be up-regulated by exposure to IFN-gamma. Induction of cytokine mRNA and activation of the signal proteins were detected after stimulation with rotavirus dsRNA. Apoptosis was induced and epithelial migration into the wound area was dose-dependently diminished (44.1-94.4%, P < 0.01) by exposure to rotavirus dsRNA. Diminishment of wound repair was suppressed by anti-TLR3 antibody or caspase inhibitor. CONCLUSION: Rotavirus dsRNA induces severe apoptosis and diminishes wound repair in IEC through TLR3, which might be involved in the pathogenesis of rotavirus-induced enteritis.

Orally administrated rare earth element cerium induces metallothionein synthesis and increases glutathione in the mouse liver.

The influence of oral administration of rare earth element cerium (Ce) was studied in relation to metallothionein (MT) and glutathione (GSH) content in the organs of ICR mice, which were administered heavy metal cadmium (Cd) for comparison. Male ICR mice were divided into 9 groups: 1 control group, 4 cerium groups and 4 cadmium groups, each with 4 mice, for a total of 36 mice. Ce groups included a 20 ppm CeCl3 diet (Ce-low) group and a 200 ppm CeCl3 diet (Ce-high) group, as did Cd groups, i.e., a 20 ppm CdCl2 diet (Cd-low) group and a 200 ppm CdCl2 diet (Cd-high) group. Each group was subdivided in 2 groups except a control group: 6-week administration group and 12-week administration group. The level of plasma aspartate aminotransferase(AST) activity, plasma alanine aminotransferase(ALT) activity, plasma cholesterol and plasma triglyceride in the Ce-low, Cd-low, Ce-high, and Cd-high group were higher than that of control group, although there were no significant differences (p > 0.05). By contrast, both Ce and Cd groups had higher levels of MT and GSH in hepatic cells compared to the control group (p < 0.05) and decreased liver tissue level of lipoperoxide (p < 0.05). These groups also had decreased plasma superoxide dismutase (SOD) activity (p < 0.05), and increased plasma level of lipoperoxide (p > 0.05). In conclusion, it is suggested that orally administered Ce increases MT and GSH as an antioxidant in the mouse liver, and these reaction are probably caused by increases in the oxidative stress with Ce.

Protection of hepatocytes from apoptosis by a novel substance from actinomycetes culture medium.

A novel substance, #675, found from an Streptomyces sp. SM675 culture medium, dose-dependently stimulates the proliferation of human functional liver cell 4 (FLC4). When FLC4 cells were incubated under conditions without fetal bovine serum (FBS), typical features of apoptotic cell death such as shrinkage and nuclear condensation appeared; high molecular weight (HMW) DNA fragments were found; and caspase-3 and poly (ADP-ribose) polymerase (PARP) proteins were cleaved. When FLC4 cells were incubated with #675 and without FBS, the cells grew healthy, no HMW DNA fragments were found, and caspase-3 and PARP cleavage weakened, suggesting that #675 protects FLC4 cells from apoptosis induced by FBS-deprivation. The quantitative reverse-transcribed polymerase chain reaction did not show differences in PARP or Bcl-2 mRNA expression in FLC4 cells incubated with or without #675, indicating other genes may be involved in this anti-apoptosis effect. These results show that #675 enhances FLC4 proliferation via an apoptosis-inhibition pathway, implying potential pharmacological and clinical applications.

Age-associated cardiomyopathy in heterozygous carrier mice of a pathological mutation of carnitine transporter gene, OCTN2.

The purpose of this study was to test whether heterozygotes of juvenile visceral steatosis mice, a model for systemic carnitine deficiency, may develop age-associated cardiomyopathy. Tissue morphological observations were carried out by light and electron microscopy to compare the heterozygous and age-matched control mice at periods of 1 and 2 years. Possible effects of the pathological mutation on lipid and glucose levels was also evaluated in humans and mice. Except mild increases in serum cholesterol levels in male heterozygous mice and humans, no changes were found in other factors, indicating that none of the confounding factors seems to be profound. Results demonstrated that heterozygous mice had larger left ventriclular myocyte diameters than the control mice. Morphological changes in cardiac muscles by electron microscopy revealed age-associated changes of lipid deposition and abnormal mitochondria in heterozygous mice. Two out of 60 heterozygous cohort and one out of nine heterozygous trim-kill mice had cardiac hypertrophy at ages older than 2 years. The present study and our previous work suggest that the carrier state of OCTN2 pathological mutations might be a risk factor for age-associated cardiomyopathy.

Complications of IgA nephropathy in a non-insulin-dependent diabetes model, the Akita mouse.

The Akita mouse, which has a mutation (Cys96Tyr) in the insulin 2 gene (Ins2(Akita)), is a model for diabetes. The male Akita mouse has diabetes, while females develop mild diabetes. This study aimed to investigate renal complications in the Akita mouse model, which has been maintained in a heterozygous state Ins2(Akita) (+/-) with a C57BL/6 background (B6). Renal function (BUN, creatinine), serum IgA concentrations and histological changes in the kidneys were evaluated in diabetic and control mice in a B6 background. Five each of male and female mice per group (diabetes vs. control) were killed at 10, 20, 30 and 40 weeks of age. The influence of major histocompatibility antigens (MHC) on renal complications was tested using male diabetic mice in a C3H/He (C3H) background. When compared with controls, diabetic males, but not females, developed impaired renal function with elevation of serum IgA after 30 weeks of age. Diabetic glomerulosclerosis advanced with age in both sexes. Diffuse granular mesangial deposits of IgA were detected by immunofluorescence microscopy in diabetic males after 20 weeks. We tested whether the IgA-associated lesions were influenced by MHC using diabetic males in a C3H background. Similar degrees of diabetic glomerulosclerosis and glomerular IgA deposition were found in mice with C3H and B6 backgrounds. Akita mouse is a unique mouse model showing both mesangial sclerosis and IgA nephropathy.