We have previously reported that decrease in level of serum thyroxine T4 by Kanechor 500 (KC500) in rats would occur through the increase in hepatic T4 accumulation rather than the increase in hepatic T4-glucuronyl transferase activity. In the present study, to understand the mechanism underlying the KC500-mediated increase in hepatic T4 accumulation, we examined the relationship between the KC500-mediated changes in hepatic T4 accumulation and the expression levels of mRNAs of hepatic transporters including T4 transporters. [125I]T4 was intravenously injected into KC500-pretreated and control (KC500-untreated) Wistar rats, and [125I]T4 uptake levels of liver parenchymal cells were comparatively examined. The amount of [125I]T4 uptake by hepatic cells increased in a time-dependent manner up to 96 hr after KC500 treatment. Following KC500 treatment, a time-dependent increase in the mRNA level of hepatic T4 influx transporter LAT1 was observed up to 96 hr later, while a significant increase in hepatic T4 influx transporter Oatp2 mRNA occurred only at 96 hr later. No KC500-mediated increases in the mRNAs of other hepatic transporters (Oatp1, Oatp3, Oatp4, Ntcp, LAT2, and Mrp2) were observed at any timepoints, although the mRNA expression of the T4 conjugate(s) efflux transporter Mrp3 significantly increased in a time-dependent manner 24-96 hr following KC500 treatment. The present findings suggest that KC500-mediated increase in hepatic T4 accumulation occurs, at least in part, through the increase in the expression of hepatic T4-transporters, such as LAT1 and Oatp2.
Mice lacking farnesoid X receptor (FXR) are used as a model for nonalcoholic fatty liver disease because their livers exhibit hepatomegaly, hepatic steatosis, and hepatic inflammation. The influence of fish oil feeding on hepatomegaly and disrupted hepatic function was investigated using female Fxr-null mice and wild-type mice fed a fish oil diet (2% fish oil and 2% corn oil) or a control diet (4% corn oil) for 4 weeks. Hepatic n-3 polyunsaturated fatty acid (PUFA) levels, including 22:6 n-3 docosahexaenoic acid (DHA) and 20:5 n-3 eicosapentaenoic acid (EPA) were significantly higher in the fish oil group than those in the control group of Fxr-null mice and wild-type mice. Fxr-null mouse livers of the control group showed a whitish brown coloration, whereas Fxr-null mouse livers of the fish oil group showed a dark brown coloration similar to that of wild-type mice. The liver in Fxr-null mice of the fish oil group was smaller than that of the control group. There was a significant decrease in the levels of hepatic damage-associated diagnostic markers, hepatic and serum bile acids, triglycerides, free fatty acids, and total cholesterol levels in Fxr-null mice because of fish oil feeding. It also reversed elevated mRNA levels of oxidative stress-related genes (Hmox1, Gsta1, and Gsta2) and reduced mRNA levels of transcriptional factors (Pparα and Shp) in Fxr-null mice. These results suggest that fish oil feeding reverses hepatomegaly and disrupted hepatic function due to the lack of FXR signaling.
Organic-inorganic hybrid molecules, which are composed of organic-ligand(s) and metal(s), are indispensable as synthetic reagents in chemistry, but they have made very little in the way of contributions to biological research. Previously, we reported that the cytotoxicity of organic-inorganic hybrid molecules in vascular endothelial cells depends on interactions between the intramolecular metal and ligand, but remains independent of the hydrophobicity of the intramolecular metal(s). Herein, we show a synergistic cytotoxicity produced by forming a complex of copper and 2,9-dimethyl-1,10-phenanthroline in vascular endothelial cells that depends on the intracellular accumulation of copper.
To obtain background data of NOD/Shi-scid IL-2Rγnull (NOG) mice, severely immunedeficient mice, a total of 120 animals were examined at 7, 26 and 52 weeks-old (20 mice/sex/group). The survival rate at 52 weeks-old was 95% (19/20) in both sexes. Clinically, circling behavior in one direction along the cage wall was observed in males after 8 weeks and females after 47 weeks-old, and hunchback position was found in males after 32 weeks-old. Hematologically, lymphocyte count markedly decreased at all ages, while white blood cell count increased in several mice at 52 weeks-old. Blood chemistry results revealed high values of aspartate aminotransferase, lactate dehydrogenase and creatine phosphokinase in some females at 26 weeks-old, without any related histological change. Histologically, lymphoid hypoplasia characterized by severe lymphocyte depletion with poorly developed tissue architectures was observed. In addition, spongiotic change in the nerve tissue was observed in both sexes at 7 and 26 weeks-old, and intracytoplasmic materials known as tubular aggregates in the skeletal muscles were found in males terminated at 26 and 52 weeks-old and in females at 52 weeks-old. Malignant lymphoma was found in one female euthanized at 20 weeks-old. Further, small intestinal adenoma, hepatocellular adenoma, leukemia, cerebral lipomatous hamartoma, Harderian gland adenoma and uterine polyp were also observed, and their incidences were low except for that of uterine polyp. This study provided detailed background data on NOG mice up to 52 weeks-old and provided information on appropriate use of NOG mice in the various research fields.
Ethylene glycol monomethyl ether (EGME), which is widely used in various industrial products, is known for adverse effects on the reproductive system in adult rats. However, the effects of EGME on reproductive development in juvenile rats have not been demonstrated. In order to investigate the effects of EGME on the female reproductive system and pubertal development in juvenile rats, EGME was administered to female Sprague Dawley rats from postnatal day 21 to 41 at a dose level of 0, 50, 100, or 300 mg/kg. The animals were examined for general condition, body weight, vaginal opening (VO), estrous cyclicity, and histopathology of reproductive organs. EGME treatment resulted in a prolonged estrous cycle interval characterized by persistent diestrus at 50 mg/kg without effects on body weight, timing of VO, or histology of the reproductive organs. EGME at 100 mg/kg induced decreases in body weight gain, a delay of VO, and irregular estrous cycle with absence of corpora lutea and hypertrophy of uterine epithelium indicating disturbance of the ovulatory process associated with hormonal effect. At 300 mg/kg, there was significant delay of puberty due to severe growth retardation. The present results revealed that irregular estrous cycle is a first indicator of the effects of EGME on the female reproductive system in juvenile rats, with delayed pubertal onset and ovulatory process disturbance at a higher dose.
Plasma amino acid level changes occur in mild, moderate and severe stages of liver injury in human patients. In animal models, however, data are mainly restricted to severe liver injury models in rats. Here we present the characterization of a rat model of moderate liver dysfunction secondary to alpha-napthylisothiocyanate (ANIT)-induced cholestasis. Rats treated with 30 mg/kg/day ANIT for 3 weeks exhibited a time-dependent increase in plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST) and bilirubin levels and a decrease in albumin concentration. According to a liver dysfunction evaluation based on the human Child-Pugh-Score, animals developed a moderate liver dysfunction in the first two weeks of ANIT treatment, while only a mild dysfunction was observed at the end of week 3 despite ongoing ANIT administration. Univariate analysis of branched-chain amino acid plasma levels indicated that reduced levels of branched chain amino acids were associated with the ANIT treatment. These data may set the stage for further research of amino acid disturbances and requirements in non-severe cholestasis.
Nanomaterials have been extensively used in our daily life, and may also induce health effects and toxicity. Nanomaterials can translocate from the outside to internal organs, including the brain. For example, both nano-ZnO and nano-TiO2 translocate into the brain via the olfactory pathway in rodents, possibly leading to toxic effects on the brain. Although the effects of nano-ZnO and nano-TiO2 on neuronal viability or neuronal excitability have been studied, no work has focused on how these nanomaterials affect neuronal differentiation and development. In this study, we investigated the effects of nano-ZnO and nano-TiO2 on neurite outgrowth of PC12 cells, a useful model system for neuronal differentiation. Surprisingly, the number, length, and branching of differentiated PC12 neurites were significantly suppressed by the 7-day exposure to nano-ZnO (in the range of 1.0 × 10-4 to 1.0 × 10-1 µg/mL), at which the cell viability was not affected. The number and length were also significantly inhibited by the 7-day exposure to nano-TiO2 (1.0 × 10-3 to 1.0 µg/mL), which did not have cytotoxic effects. These results demonstrate that the neurite outgrowth in differentiated PC12 cells was suppressed by sub-cytotoxic concentrations of nano-ZnO or nano-TiO2.
Fish are exposed to different heavy metals that may induce numerous physiological changes. In the present study, we examined the redox state in response to a severe stress resulting from two heavy metals (Zinc and Lead) contamination in carp Cirrhinus cirrhosus. Fish were exposed to 1/10th of LC50 of the respective metals [zinc chloride (2.72 mg/L) and lead acetate (2.53 mg/L)] for 30 days and allowed to recover for another 30 days without any metal exposure. Concentration of metals, different enzymatic and non-enzymatic antioxidant agents and expression levels of heat shock protein (HSP) 70 and 90 were measured in the liver and the kidney of fish. The lipid peroxide levels in fish tissues gradually increased with duration of treatment for both metals. After 15 days of treatment, glutathione (GSH) levels had increased, but decreased as the treatment continued for 30 days and returned to basal levels after a 30-day recovery period. Activities of all the anti-oxidant enzymes, except glutathione peroxidase, in stressed fish were significantly increased compared to those in the control at 15 days and continued till the 30th day of treatment, showing a tendency to return to basal levels after the recovery period. Expression levels of HSP70 and HSP90 gradually increased after zinc and lead treatment, respectively. The expression of HSP was higher in the liver. The results suggest that different heavy metals may have differential effects on the redox state and induction of oxidative stress in carp, in vivo.
In order to elucidate the effect of chorioallantoic and yolk sac placenta on the embryonic/fetal toxicity in dibutyltin dichloride (DBTCl)-exposed rats, we examined the histopathological changes and the tissue distribution of dibutyltin in the placentas and embryos. DBTCl was orally administered to the groups at doses of 0 mg/kg during gestation days (GD)s 7-9 (control group) and 20 mg/kg during GDs 7-9 (GD7-9 treated group), and GDs 10-12 (GD10-12 treated group). The total fetal mortality was increased, and malformations characterized by craniofacial dysmorphism were detected in the GD7-9 treated group. The embryonic/fetal weight and placental weight showed a decrease in both DBTCl-treated groups. Histologically, some embryos on GD 9.5 in the GD7-9 treated group underwent apoptosis without any changes of yolk sac. In the laser ablation-inductively coupled plasma-mass spectrometry analysis (LA-ICP-MS), tin was detected in the embryo, allantois, yolk sac, ectoplacental cone and decidual mass surrounding the conceptus on GD 9.5 in the GD7-9 treated group. Thus, it is considered that the embryo in this period is specifically sensitive to DBTCl-induced apoptosis, compared with other parts. The chorioallantoic placentas in both DBTCl-treated groups showed the developmental delay and hypoplasia in the fetal parts of placenta, resulting from apoptosis and mitotic inhibition. Thus, it was speculated that the DBTCl-induced malformations and fetal resorption resulted from the apoptosis in the embryo caused by the direct effect of DBTCl. The DBTCl-induced lesions in the chorioallantoic placenta were a non-specific transient developmental retardation in the fetal parts of placenta, leading to intrauterine growth retardation.
In recent years, human-induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) have been widely used to develop evaluation systems for drug cardiotoxicity, including the arrhythmia caused by QT prolongation. To accurately assess the arrhythmogenic potential of drugs, associated with QT prolongation, we developed an evaluation system using hiPS-CMs and gene expression analysis. hiPS-CMs were treated with 8 arrhythmogenic and 17 non-arrhythmogenic drugs at several concentrations for 24 hr to comprehensively analyze gene expression. The results showed that 19 genes were upregulated in the arrhythmogenic drug-treated cells compared with their expression levels in the non-treated and non-arrhythmogenic drug-treated cells. The arrhythmogenic risks of the drugs were evaluated by scoring gene expression levels. The results indicated that arrhythmogenic risks could be inferred when cells were treated at a concentration 100 times higher than the maximum blood concentration of the drug. Thus, we succeeded in developing a system for evaluation of the arrhythmogenic potential of drugs using gene expression analysis.
In order to investigate the effects of RhoA/ROCK signaling in macrophage differentiation, we used 100 ng/mL PMA to induce macrophage differentiation from U937 cells in vitro. The observation of cell morphology and the expression of CD68 and SR-A were performed to confirm the differentiation induced by PMA. Western blot analysis showed that the expression of ROCK1 and ROCK2 and the phosphorylation of MYPT1 were significantly increased after PMA treatment. Pulldown assay showed that the activation of RhoA was obviously enhanced when U937 cells were treated with PMA. In order to further demonstrate whether RhoA/ROCK signaling could mediate the macrophage differentiation induced by PMA, we successfully suppressed the expression of RhoA, ROCK1 and ROCK2 by performing siRNA technology in U937 cells, respectively. The macrophage differentiation and the expression of CD68 and SR-A were significantly inhibited by the suppression of RhoA, ROCK1 or ROCK2 in PMA-induced U937 cells, indicating that the macrophage differentiation induced by PMA is associated with RhoA/ROCK signaling pathway. In addition, we pretreated U937 cells with Y27632 (ROCK inhibitor, 20 μM) for 30 min and then observed the macrophage differentiation induced by PMA. The result illustrated that Y27632 pretreatment obviously inhibited PMA-induced differentiation and the expression of CD68 and SR-A. In conclusion, the activation of RhoA/ROCK signaling is responsible for the macrophage differentiation induced by PMA.
High dietary levels of the non-genotoxic synthetic pyrethroid momfluorothrin increased the incidence of hepatocellular tumors in male and female Wistar rats. Mechanistic studies have demonstrated that the mode of action (MOA) for momfluorothrin-induced hepatocellular tumors is constitutive androstane receptor (CAR)-mediated. In the present study, to evaluate the potential human carcinogenic risk of momfluorothrin, the effects of momfluorothrin (1-1,000 µM) and a major metabolite Z-CMCA (5-1,000 µM) on hepatocyte replicative DNA synthesis and CYP2B mRNA expression were examined in cultured rat and human hepatocyte preparations. The effect of sodium phenobarbital (NaPB), a prototypic rodent hepatocarcinogen with a CAR-mediated MOA, was also investigated. Human hepatocyte growth factor (hHGF) produced a concentration-dependent increase in replicative DNA synthesis in rat and human hepatocytes. However, while NaPB and momfluorothrin increased replicative DNA synthesis in rat hepatocytes, NaPB, momfluorothrin and Z-CMCA did not increase replicative DNA synthesis in human hepatocytes. NaPB, momfluorothrin and Z-CMCA increased CYP2B1/2 mRNA levels in rat hepatocytes. NaPB and momfluorothrin also increased CYP2B6 mRNA levels in human hepatocytes. Overall, while momfluorothrin and NaPB activated CAR in cultured human hepatocytes, neither chemical increased replicative DNA synthesis. Furthermore, to confirm whether the findings observed in vitro were also observed in vivo, a humanized chimeric mouse study was conducted. Replicative DNA synthesis was not increased in human hepatocytes of chimeric mice treated with momfluorothrin or its close structural analogue metofluthrin. As human hepatocytes are refractory to the mitogenic effects of momfluorothrin, in contrast to rat hepatocytes, the data support the hypothesis that the MOA for momfluorothrin-induced rat liver tumor formation is not relevant for humans.
To investigate the effects of perinatal exposure to tetrabromobisphenol A (TBBPA), a brominated flame retardant, on the immune system, a respiratory syncytial virus (RSV) infection mouse model was utilized. Female mice were exposed to TBBPA mixed with the diet from 10 days after conception to weaning on postnatal day 21. Offspring mice were infected intranasally with A2 strain of RSV. Although no general toxicological sign was observed, the pulmonary viral titers of offspring mice exposed to 0.1% TBBPA were significantly increased compared with the control on day 5 post-infection. TBBPA did not affect RSV growth in vitro. Histopathological analysis confirmed that the exacerbation of interstitial pneumonia was due to TBBPA- exposure in the lung tissues in RSV-infected offspring. Moreover, gene expression of interleukin (IL)-24 was shown to be elevated typically in the lung tissues of TBBPA-treated offspring by a DNA microarray and was also confirmed by immunohistopathological analysis using an anti-IL-24 antibody. Thus, developmental exposure to TBBPA affected the immune response to RSV infection, resulting in the exacerbation of pneumonia. Thus, IL-24 should be a key molecule to understand the mechanism of action of TBBPA.
Safety assessments of cosmetics are carried out by identifying possible harmful effects of substances in cosmetic products and assessing the exposure to products containing these substances. The present study provided data on the amounts of cosmetic products consumed in Japan to enhance and complement the existing data from Europe and the United States, i.e., the West. The outcomes of this study increase the accuracy of exposure assessments and enable more sophisticated risk assessment as a part of the safety assessment of cosmetic products. Actual amounts of products applied were calculated by determining the difference in the weight of products before and after use by approximately 300 subjects. The results of the study of skincare products revealed that in comparison with the West, large amounts of lotions and emulsions were applied, whereas lower amounts of cream and essence were applied in Japan. In the study of sunscreen products, actual measured values during outdoor leisure use were obtained, and these were lower than the values from the West. The study of the use of facial mask packs yielded data on typical Japanese sheet-type impregnated masks and revealed that high amounts were applied. Furthermore, data were obtained on cleansing foams, makeup removers and makeup products. The data from the present study enhance and complement existing information and will facilitate more sophisticated risk assessments. The present results should be extremely useful in safety assessments of newly developed cosmetic products and to regulatory authorities in Japan and around the world.