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Archives of Toxicology (v.83, #9)
Chronic effects of perfluorooctanesulfonate exposure on immunotoxicity in adult male C57BL/6 mice by Guang-Hui Dong; Ying-Hua Zhang; Li Zheng; Wei Liu; Yi-He Jin; Qin-Cheng He (pp. 805-815).
A paucity of data exists to corroborate the few studies that report immune suppression after exposure to perfluorooctanesulfonate (PFOS). In this study, adult male C57BL/6 mice were exposed to PFOS daily via gavage for 60 days [0, 0.5, 5, 25, 50, or 125 mg/kg total administered dose (TAD)]. The results showed that liver mass was significantly increased at ≥5 mg PFOS/kg TAD and in a dose-dependent manner. Lymphocyte proliferation and natural killer cell activity were altered in male mice. Plaque forming cell (PFC) response was suppressed beginning at 5 mg/kg TAD. Based on the liver mass and PFC response, the no observed adverse effect level and lowest observed adverse effect level for male mice exposed PFOS for 60 days was 0.5 and 5 mg/kg TAD, respectively. Measured PFOS serum concentrations at these dose levels were 0.674 ± 0.166 and 7.132 ± 1.039 mg/l, respectively. These results indicate that PFOS exposure can affect the immunity function in mice at levels approximately 50-fold for highly exposed human populations.
Keywords: Perfluorooctanesulfonate; Immunotoxicity; PFC response
Suppression of acrylamide toxicity by carboxyfullerene in human neuroblastoma cells in vitro by Tomoyuki Sumizawa; Hideki Igisu (pp. 817-824).
In our previous study, we found that caspase-dependent apoptosis played a role in the genesis of toxicity of acrylamide in human neuroblastoma (SH-SY5Y) cells (Sumizawa and Igisu in Arch Toxicol 81:279–282, 2007). In the present experiment, we examined whether carboxyfullerene may suppress the cytotoxicity of acrylamide because carboxyfullerene has been reported to protect nerve cells from various pathologic processes including apoptosis. Carboxyfullerene lowered lactate dehydrogense leakage and elevated cell viability in SH-SY5Y cells exposed to acrylamide. It also lowered caspase-3 activities and cell population in the sub-G1 phase induced by acrylamide. Nevertheless, carboxyfullerene enhanced cellular uptake of [14C]acrylamide. On the other hand, acrylamide markedly decreased glutathione (GSH)-content in cells and carboxyfullerene blocked the decrease. The toxicity of acrylamide was suppressed by adding GSH or GSH monoethyl ester, whereas it was not lowered by carboxyfullerene when GSH synthesis was inhibited by l-buthionine-(S,R)-sulfoximine. Thus, the cytotoxicity of acrylamide including apoptotic processes is closely related to GSH level in SH-SY5Y cells and carboxyfullerene suppresses the toxicity by maintaining GSH content. Neither tricarboxylic acids without fullerene moiety nor hydroxylated fullerene showed comparable effects of carboxyfullerene (60 μM) against 1–5 mM acrylamide, suggesting the importance of the three malonic acid groups at specific positions in a fullerene molecule for the effects.
Keywords: Acrylamide; SH-SY5Y cells; Apoptosis; Neurotoxicity; Carboxyfullerene; Nanoparticle
The anti-apoptotic effects of caspase inhibitors on propyl gallate-treated HeLa cells in relation to reactive oxygen species and glutathione levels by Yong Hwan Han; Hwa Jin Moon; Bo Ra You; Woo Hyun Park (pp. 825-833).
Propyl gallate (PG) as a synthetic antioxidant is widely used in processed food, cosmetics and medicinal preparations. Despite the assumed low toxicity of PG, it exerts a variety of effects on tissue and cell functions. In the present study, we evaluated the anti-apoptotic effects of caspase inhibitors on PG-treated human cervix adenocarcinoma HeLa cells in relation to the changes of reactive oxygen species (ROS) and glutathione (GSH) levels. PG induced apoptosis in a dose-dependent manner, as evidenced by sub-G1 cells and annexin V staining cells. Treatment with pan-caspase inhibitor, caspase-3 inhibitor, caspase-8 inhibitor or caspase-9 inhibitor significantly prevented apoptosis in PG-treated HeLa cells at 24 h. The intracellular ROS levels including O 2 •− were increased or decreased in PG-treated HeLa cells depending on the incubation times (1 or 24 h). PG depleted intracellular GSH content in HeLa cells at 24 h. Treatment with caspase inhibitor reduced ROS levels and significantly prevented GSH depletion in PG-treated HeLa cells at 24 h. In conclusion, PG induced apoptosis in HeLa cells. The anti-apoptotic effect of caspase inhibitor on PG-induced HeLa cell death was closely related to the reduction of ROS levels, especially mitochondrial O 2 •− , as well as to the inhibition of GSH depletion.
Keywords: Propyl gallate; Apoptosis; HeLa; Caspase; ROS; GSH
Trichloroethylene liver toxicity in mouse and rat: microarray analysis reveals species differences in gene expression by Yuri Sano; Hiroshi Nakashima; Noriyuki Yoshioka; Norihito Etho; Tetsuo Nomiyama; Yuji Nishiwaki; Toru Takebayashi; Kazuyuki Oame (pp. 835-849).
Trichloroethylene (TCE), an industrial organic solvent found in the environment, is a known carcinogen in laboratory animals and is believed to be carcinogenic in humans. Its carcinogenicity is subject to species-specific differences in biological activity, causing hepatocellular carcinoma in mouse and renal-cell carcinoma in rat. We have sought to better understand TCE’s mode of action (MOA) by studying the alterations in gene expression profiles of liver in mice and rats that were administrated TCE by oral gavage either once or daily for 14 days. Microarray analysis revealed distinct transcriptional profiles and differences in biological pathways not only species-specific, but also pulse-dose effects within each species. For example, inhibition of the TGF-β pathway and activation of MAPK signaling were specific to mice repeatedly exposed to TCE. A better understanding of the MOA in mice and rats will lead to better hypotheses of TCE’s affect on humans.
Effects of perfluorooctanoate and perfluorooctane sulfonate exposure on hepatoma Hep G2 cells by Xiao-Zhong Hu; De-Cong Hu (pp. 851-861).
Perfluorinated compounds (PFCs) are emerging compounds of concern. They are widely distributed in the environment, wildlife and human. Concern has been raised over their possible adverse effects on human health. This study was designed to determine cytotoxic effects of two important PFCs, perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS), in a single and a mixture of them exposure to Hep G2 cells. The results showed that PFOA and PFOS (50–200 μmol/l) induced production of reactive oxygen species (ROS), dissipation of mitochondria membrane potential and apoptosis of Hep G2 cells. Moreover, activities of superoxide dismutase, catalase and glutathione reductase were increased, whereas activities of glutathione-S-transferase and glutathione peroxidase were decreased. Glutathione content was reduced. Differential expression of genes, such as p53, Bcl-2, caspase-9, was evident in PFOA or PFOS exposure groups. The possible mechanism was that they could overwhelm homeostasis of antioxidative systems, boost ROS generation, impact mitochondria, and affect genes expression of apoptotic regulators, which resulted in start-ups of apoptosis program. Cells exposed to mixture of PFOA and PFOS and each of them showed non-apoptotic rate significant difference, which indicated that the combined effect of two compounds was summation effect, but neither synergistic nor antagonistic effect.
Keywords: PFOA; PFOS; Cytotoxic effects; Complex exposure
Prednisone reduces ketoconazole-induced skeletal defects in rat fetuses by Vanessa Cristiane Santana Amaral; Guilhermino Pereira Nunes Jr (pp. 863-871).
Ketoconazole (KT) is a broad-spectrum antifungal agent whose pharmacological activity is based on the capability to interfere with steroid biosynthesis through an interaction with fungal cytochrome P-450 enzymes and thereby avoiding the formation of fungal walls. As the inhibition of fungal cytochrome P-450 by KT is not specific, the mammalian cytochrome P-450 species, which play an important role in the biosynthesis of steroidogenesis, are also affected. The reproductive and developmental toxicity of KT have been assessed. This antimycotic agent has been reported as embryotoxic and teratogenic when administered in high doses (80 mg/kg) to pregnant rats. The mechanisms by which KT exert teratogenic effects remains to be elucidated. When considering the potential inhibitory effect of KT on mammalian steroid biosynthesis as a possible responsible for the skeletal anomalies induced by this drug, this study aimed at determining whether steroid maternal supplementation may prevent the skeletal anomalies induced by KT. To test this hypothesis, maternal supplementation with prednisone (PRED) (0.1, 0.2 or 0.4 mg/kg) and 80 mg/kg of KT were administered to pregnant Wistar rats (n = 10) during organogenesis period. On gestational day 21, the dams were euthanized and examined for standard parameters of reproductive outcome. In summary, the results showed that PRED supplementation therapy may cause reductions in the incidence of KT-induced cranial and appendicular skeletal anomalies as well as cleft palate in the rat, being these results more consistent with 0.4 mg/kg of this drug. These results suggest an important role for glucocorticoids in KT-induced teratogenesis
Keywords: Embryotoxicity; Ketoconazole; Maternal toxicity; Prednisone; Skeletal anomalies
3-Hydroxybenzo(a)pyrene as a biomarker of dermal exposure to benzo(a)pyrene by Jean-Paul Payan; Michel Lafontaine; Patrice Simon; Fabrice Marquet; Catherine Champmartin-Gendre; Dominique Beydon; Ludivine Wathier; Elisabeth Ferrari (pp. 873-883).
The aim of this study was to determine the percutaneous absorption flux of BaP (20 μg/cm2 in ethanol) and the usefulness of urinary 3-OHBaP as a bio-indicator of dermal exposure to BaP. The percutaneous absorbed dose and absorption flux were estimated by comparison with intravenous administration of BaP (0.01 and 0.05 mg/kg in Cremophor®) as reference way. A percutaneous absorption flux of 0.37 μg/cm²/h was determined by killing groups of rats, following exposure time of 4.5 and 24 h. [14C] skin content was 3.1 μg/cm2, after 24 h exposure to BaP. Total urinary 3-OHBaP accounted for 0.4% of the real absorbed dose, which was fourfold higher than the percentage of an intravenous dose excreted as 3-OHBaP. This finding reveals that percutaneous absorption of BaP, based on the ratio of urinary excretion of 3-OHBaP following percutaneous exposure compared to percutaneous absorption following intravenous administration of BaP, is overestimated in the rat. In vitro, BaP was intensively metabolised by rat skin. Unchanged BaP and 3-OHBaP in receptor fluid accounted for 50 and 30% of the total radioactivity. This percutaneous first past effect of BaP in rats could, in part, explain the higher urinary excretion ratio of 3-OHBaP compared to the value based on intravenous administration of BaP. Conversely, BaP was largely lower metabolised as 3-OHBaP during percutaneous absorption by humans, so BaP absorption flux should be overestimated to a lesser extent in humans than in rats.
Keywords: 3-Hydroxybenzo(a)pyrene; Polycyclic aromatic hydrocarbons; Percutaneous absorption; Biomarker; Urine; Rat; Human