Rat pancreatitis produced by 13‐week administration of zinc oxide nanoparticles: biopersistence of nanoparticles and possible solutions

Zinc oxide (ZnO) nanoparticles (NPs) are used in diverse applications ranging from paints and cosmetics to biomedicine and food. Although micron‐sized ZnO is a traditional food supplement, ZnO NPs are an unknown public health risk because of their unique physicochemical properties. Herein, we studied the 13‐week subchronic toxicity of ZnO NPs administered via the oral route according to Organization for Economic Cooperation and Development (OECD) test guideline 408. Well‐dispersed ZnO NPs were administered to Sprague–Dawley (SD) rats (11/sex/group) at doses of 67.1, 134.2, 268.4 or 536.8 mg kg^–1 per body weight over a 13‐week period. The mean body weight gain in males given 536.8 mg kg^–1 ZnO NPs was significantly lower than that of control male rats, whereas no significant differences were observed between the other treatment groups and the controls. Male and female rats dosed at 536.8 mg kg^–1 ZnO NPs had significant changes in anemia‐related hematologic parameters. Mild to moderate pancreatitis also developed in both sexes dosed at 536.8 mg kg^–1, whereas no histological changes were observed in the other treatment groups. To evaluate the mechanism of toxicity, we performed a bio‐persistence study and evaluated the effects of the ZnO NPs on cell proliferation. The treatment of a human gastric adenocarcinoma cell line with ZnO NPs resulted in a significant inhibition of cellular proliferation. The anti‐proliferative effect of ZnO NPs or Zn²⁺ was effectively blocked by treatment with chelators. These results indicate that the bio‐persistence of ZnO NPs after ingestion is key to their toxicity; the no‐observed‐adverse effect level (NOAEL) of ZnO NPs was found to be 268.4 mg kg^–1 per day for both sexes. Copyright © 2013 John Wiley & Sons, Ltd.     

Comparison of distribution and toxicity of different types of zinc‐based nanoparticles

Zinc‐based nanoparticles (Zn‐NPs), mainly zinc oxide (ZnO) NPs, have promising application in a wide area, but their potential harmful effects on environment and human health have been continuously raised together with their high dissolution rate. In this study, we coated the surface of ZnO NPs with phosphate (ZnP NPs) and sulfide (ZnS NPs) which have very low solubility in water, administered orally (0.5 and 1 mg/kg) to mice for 28 days, and then compared their biodistribution and toxicity. As expected, ZnO NPs were rapidly ionized in an artificial gastric fluid. On the other hand, ZnO NPs were more particlized in an artificial intestinal fluid than ZnP and ZnS NPs. After repeated dosing, all three types of Zn‐NPs the most distributed in the spleen and thymus and altered the level of redox reaction‐related metal ions in the tissues. We also found that three types of Zn‐NPs clearly disturb tissue ion homeostasis and influence immune regulation function. However, there were no remarkable difference in distribution and toxicity following repeated exposure of three types of Zn‐NPs, although Na+ and K+ level in the spleen and thymus were notably higher in mice exposed to ZnO NPs compared to ZnP and ZnS NPs. Taken together, we suggest that all three types of Zn‐NPs may influence human health by disrupting homeostasis of trace elements and ions in the tissues. In addition, the surface transformation of ZnO NPs with phosphate and sulfide may not attenuate toxicity due to the higher particlization rate of ZnO NPs in the intestine, at least in part. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1363–1374, 2017.     

Toxicity of ZnO/TiO2‐conjugated carbon‐based nanohybrids on the coastal marine alga Thalassiosira pseudonana

Increasing consumption of metal‐oxide nanoparticles (NPs) and carbon‐based nanomaterials has caused significant concern about their potential hazards in aquatic environments. The release of NPs into aquatic environments could result in adsorption of NPs on microorganisms. While metal‐oxide NP‐conjugated carbon‐based nanohybrids (NHs) may exhibit enhanced toxicity toward microorganisms due to their large surface area and the generation of reactive oxygen species (ROS), there is a lack of information regarding the ecotoxicological effects of NHs on marine diatom algae, which are an indicator of marine pollution. Moreover, there is scant information on toxicity mechanisms of NHs on aquatic organisms. In this study, four NHs (ie, ZnO‐conjugated graphene oxide [GO], ZnO‐conjugated carbon nanotubes [CNTs], TiO₂‐conjugated GO, and TiO₂‐conjugated CNT) that were synthesized by a hydrothermal method were investigated for their toxicity effects on a Thalassiosira pseudonana marine diatom. The in vitro cellular viability and ROS formation employed at the concentration ranges of 50 and 100 mg/L of NHs over 72 hours revealed that ZnO‐GO had the most negative effect on T. pseudonana. The primary mechanism identified was the generation of ROS and GO‐induced dispersion that caused electrostatic repulsion, preventing aggregation, and an increase in surface areas of NHs. In contrast to GO‐induced dispersion, large aggregates were observed in ZnO/TiO₂‐conjugated CNT‐based NHs. The scanning electron microscopy images suggest that NHs covered algae cells and interacted with them (shading effects); this reduced light availability for photosynthesis. Detailed in vitro toxicity effects and mechanisms that cause high adverse acute toxicity on T. pseudonana were unveiled; this implied concerns about potential hazards of these mechanisms in aquatic ecosystems.     

Developmental toxicity and DNA damage to zebrafish induced by perfluorooctane sulfonate in the presence of ZnO nanoparticles

Perfluorooctane sulfonate (PFOS) and ZnO nanoparticles (ZnO–NPs) are frequently detected in the environment, but few studies have assessed their joint toxicity. In this study, the acute toxicity and chronic toxicity to zebrafish (Danio rerio) induced by PFOS in the presence of ZnO–NPs were investigated, including developmental toxicity and DNA damage. The embryos were exposed to PFOS (only) (0.4, 0.8, and 1.6 mg/L) and PFOS plus ZnO–NPs (0.4 + 50, 0.8 + 50, and 1.6 + 50 mg/L) solutions to evaluate mortality (96 h), body length (96 h), hatch rate (72 h), heart rate (48 h),and malformation rate (96 h). The results revealed that the co‐treatment could cause more severe developmental toxicity compared with the control and single‐treatments, and the toxic effects generally increased in a dose–response manner. In addition, adult zebrafish were exposed to single and mixed solutions of PFOS and ZnO–NPs (at the concentrations mentioned above) for 30 days. DNA damage to zebrafish was evaluated by the comet assay and micronucleus test. We found that the PFOS single‐treatment at all doses (0.4, 0.8, and 1.6 mg/L) could strongly induce DNA damage to peripheral blood cells and that ZnO–NPs could aggravate the formation of DNA damage in co‐treatments. Histological examination of liver, testicle, and ovary showed that the presence of ZnO–NPs (50 mg/L) could also cause more serious histological damage to adult zebrafish than PFOS alone. As a result, the synergistic effects played an important role during joint exposure. Our observations provide a basic understanding of the joint toxicity of PFOS and ZnO–NPs to aquatic organisms. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 360–371, 2016.     

3‐Hydroxyflavone enhances the toxicity of ZnO nanoparticles in vitro

It is recently shown that flavonoids might reduce the toxicity of nanoparticles (NPs) due to their antioxidative properties. In this study, the influence of 3‐hydroxyflavone (H3) on the toxicity of ZnO NPs was investigated. H3 increased hydrodynamic size, polydispersity index and absolute value of the zeta potential of ZnO NPs, which indicated that H3 could influence the colloidal aspects of NPs. Surprisingly, H3 markedly decreased the initial concentration of ZnO NPs required to induce cytotoxicity to Caco‐2, HepG2, THP‐1 and human umbilical vein endothelial cells, which suggested that H3 could promote the toxicity of ZnO NPs to both cancerous and normal cells. For comparison, 6‐hydroxyflavone did not show this effect. H3 remarkably increased cellular Zn elements and intracellular Zn ions in HepG2 cells following ZnO NP exposure, and co‐exposure to H3 and NPs induced a relatively higher intracellular reactive oxygen species. Exposure to ZnO NPs at 3 hours induced the expression of endoplasmic reticulum stress markers DDIT3 and XBP‐1 s, which was suppressed by H3. The expression of apoptotic genes BAX and CASP3 was significantly induced by ZnO NP exposure after 3 and 5 hours, respectively, and H3 further significantly promoted CASP3 expression at 5 hours. In combination, the results from this study suggested that H3 affected colloidal stability of ZnO NPs, promoted the interactions between NPs and cells, and altered the NP‐induced endoplasmic reticulum stress–apoptosis signaling pathway, which finally enhanced the cytotoxicity of ZnO NPs.     

Protective effects of Gαq‐RGS2 signalling inhibitor in aminophylline induced cardiac arrhythmia

An over activation of GPCR mediated Gαq dependent signalling pathway is widely associated with the development of cardiovascular abnormalities. The objective of study was to evaluate the effects of (1‐(5‐chloro‐2‐hydroxyphenyl)‐3‐(4‐(trifluoromethyl)phenyl)‐1H‐1,2,4‐triazol‐5(4H)‐one) Gαq‐RGS2 signalling inhibitor on aminophylline induced cardiac arrhythmia in rats. Rats were divided into four groups; normal rats, disease control (DC, aminophylline treated 100 mg/kg/d, i.p., 7 days), Gαq‐RGS2 signalling inhibitor (1 and 10 mg/kg/d, p.o., 7 days) treated arrhythmic rats. Gαq‐RGS2 signalling inhibitor was administered 1 hour prior to the administration of aminophylline from 1st day. At the end of study, heart rate (HR), QRS complex, QT and RR interval were measured by electrocardiogram (ECG) of anesthetized rats. Systolic and diastolic blood pressure (SBP, DBP) by invasive method, cardiac damage markers (CK‐MB, LDH) in the serum, antioxidant enzymes (SOD, catalase, glutathione) and cAMP level were measured. The treatment of Gαq‐RGS2 signalling inhibitor (10 mg/kg) significantly abolished the aminophylline induced increase of heart rate, prolongation of RR and QT interval as compared to DC rats. Gαq‐RGS2 signalling inhibitor (1 and 10 mg/kg) significantly attenuated the prolongation in QRS complex, increase of SBP, DBP and cardiac damage markers as compared to DC. Gαq‐RGS2 signalling inhibitor treatment (10 mg/kg) significantly reduced the cAMP level and increased the antioxidant enzyme level as compared to DC. Gαq‐RGS2 signalling inhibitor (10 mg/kg) showed the protective effect against the aminophylline induced cardiac arrhythmia and it might be due to improvement in cAMP level and antioxidant enzymes.     

NF‐κB activation mediates LPS‐or zymosan‐induced hypotension and inflammation reversed by BAY61‐3606, a selective Syk inhibitor,in rat models of septic and non‐septic shock

We have previously demonstrated that the activation of the spleen tyrosine kinase (Syk)/inhibitory‐κB (IκB)‐α/nuclear factor‐κB (NF‐κB) p65 signalling pathway contributes to hypotension and inflammatory response in a rat models of zymosan (ZYM)‐induced non‐septic shock. The purpose of this study was to further examine the possible mechanism underlying the effect of inhibition of Syk by BAY61‐3606 via NF‐κB activity at the level of nuclear translocation regarding the production of vasodilator and proinflammatory mediators in lipopolysaccharide (LPS) (septic)‐ and ZYM (non‐septic)‐induced shock. Administration of LPS (10 mg/kg, ip) or ZYM (500 mg/kg, ip) to male Wistar rats decreased mean arterial pressure and increased heart rate that was associated with an increase in the activities of cyclooxygenase and nitric oxide synthase, tumour necrosis factor‐α, and interleukin‐8 levels, and NF‐κB activation and nuclear translocation in sera and/or cardiovascular and renal tissues. BAY61‐3606 (3 mg/kg, ip), the selective Syk inhibitor, given 1 hour after LPS‐ or ZYM injection reversed all the above‐mentioned effects. These results suggest that Syk contributes to the LPS‐ or ZYM‐induced hypotension and inflammation associated with transactivation of NF‐κB in septic and non‐septic shock.     

Daucosterol from Crateva adansonii DC (Capparaceae) reduces 7,12‐dimethylbenz(a)anthracene‐induced mammary tumors in Wistar rats

This study aimed to evaluate the in vivo anticancer effects of daucosterol which was earlier reported to possess in vitro anticancer effects. Breast tumor was induced in 30 rats using the environmental carcinogen 7,12‐dimethylbenz(a)anthracene (DMBA) while 6 control rats received olive oil (NOR). Animals with palpable tumors were randomized into five groups (n = 6) each as follows: negative control group treated with the vehicle (DMBA); positive control group treated with 5 mg/kg BW doxorubicin (DOXO + DMBA); three groups treated with daucosterol at doses of 2.5, 5, and 10 mg/kg BW (DAU + DMBA). Treatment lasted 28 days afterward, tumor (mass, volume, cancer antigen [CA] 15‐3 level and histoarchitecture), hematological and toxicological parameters were examined. The tumor volume gradually increased in the DMBA group during the 28 days, with a tumor volume gain of ～390 cm³. Daucosterol at all doses reduced tumor volume (～133.7 cm³ at 10 mg/kg) as well as protein, malondialdehyde (MDA), and CA 15‐3 levels compared to DMBA rats. Tumor sections in daucosterol‐treated rats showed a lower proliferation of mammary ducts with mild (5 and 10 mg/kg) to moderate (2.5 mg/kg) inflammatory responses. Moreover, it exhibited an antioxidant effect, evidenced by a significant and dose‐dependent decreased in MDA levels, as well as an increase in catalase activity compared to the DMBA group. Daucosterol showed for the first time in vivo antitumor effects that corroborate its previous in vitro effects.     

Cytotoxicity,oxidative stress and inflammation induced by ZnO nanoparticles in endothelial cells: interaction with palmitate or lipopolysaccharide

Recent studies showed that ZnO nanoparticles (NPs) might induce the toxicity to human endothelial cells. However, little is known about the interaction between ZnO NPs and circulatory components, which is likely to occur when NPs enter the blood. In this study, we evaluated ZnO NP‐induced cytotoxicity, oxidative stress and inflammation in human umbilical vein endothelial cells (HUVECs), with the emphasis on the interaction with palmitate (PA) or lipopolysaccharide (LPS), because PA and LPS are normal components in human blood that increase in metabolic diseases. Overall, ZnO NPs induced cytotoxicity and intracellular reactive oxygen species (ROS) at a concentration of 32 μg ml⁻¹, but did not significantly affect the release of inflammatory cytokines or adhesion of THP‐1 monocytes to HUVECs. In addition, exposure to ZnO NPs dose‐dependently promoted intracellular Zn ions in HUVECs. PA and LPS have different effects. Two hundred μm PA significantly induced cytotoxicity and THP‐1 monocyte adhesion, but did not affect ROS or release of inflammatory cytokines. In contrast, 1 μg ml⁻¹ LPS significantly induced ROS, release of inflammatory cytokines and THP‐1 monocyte adhesion, but not cytotoxicity. The presence of ZnO NPs did not significantly affect the toxicity induced by PA or LPS. In addition, the accumulation of Zn ions after ZnO NP exposure was not significantly affected by the presence of PA or LPS. We concluded that there was no interaction between ZnO NPs and PA or LPS on toxicity to HUVECs in vitro . Copyright © 2016 John Wiley & Sons, Ltd.     

Metformin modulates cardiac endothelial dysfunction,oxidative stress and inflammation in irradiated rats: A new perspective of an antidiabetic drug

Cardiovascular disease is one of the most pivotal disorders after radiotherapy. The aim of this study investigates the possible protective effect of metformin against gamma radiation‐induced heart damage in male rats. Group 1 (control) received saline, group 2 was whole body gamma‐irradiated 5 Gy, group 3 was orally administered metformin 50 mg/kg/day for 2 weeks, group 4 received metformin 50 mg/kg/day for 1 week, then exposed to whole‐body gamma radiation at a dose of 5 Gy and continued with metformin for further 1 week. The results revealed that the administration of metformin to irradiated rats significantly ameliorated the changes in cardiac biomarkers (LDH and CK‐MB) compared with irradiated group. Heart catalase and SOD activities showed normal level when compared with the irradiated group. Also, NF‐κB, IL‐6 and TNF‐ α levels were markedly decreased compared with the corresponding values of irradiated group. Consequently, metformin reduced E‐selectin as well ICAM and VCAM‐1. These results confirmed by histopathological examination. In conclusion, concomitant administration of metformin during radiotherapy acts as a potent heart protector from oxidative stress, inflammatory mediators and endothelial dysfunction induced damages. Results thus hold a great promise for a new implication of an antidiabetic drug (metformin) as adjunct to radiotherapy.     

Melatonin attenuates 60Co γ‐ray‐induced hematopoietic,immunological and gastrointestinal injuries in C57BL/6 male mice

Protection of hematopoietic, immunological, and gastrointestinal injuries from deleterious effects of ionizing radiation is prime rational for developing radioprotector. The objective of this study, therefore, was to evaluate the radioprotective potential of melatonin against damaging effects of radiation‐induced hematopoietic, immunological, and gastrointestinal injuries in mice. C57BL/6 male mice were intraperitoneally administered with melatonin (50–150 mg/kg) 30 min prior to whole‐body radiation exposure of 5 and 7.5 Gy using ⁶⁰Co‐teletherapy unit. Thirty‐day survival against 7.5 Gy was monitored. Melatonin (100 mg/kg) pretreatment showed 100% survival against 7.5 Gy radiation dose. Melatonin pretreatment expanded femoral HPSCs, and inhibited spleenocyte DNA strands breaks and apoptosis in irradiated mice. At this time, it also protected radiation‐induced loss of T cell sub‐populations in spleen. In addition, melatonin pretreatment enhanced crypts regeneration and increased villi number and length in irradiated mice. Translocation of gut bacteria to spleen, liver and kidney were controlled in irradiated mice pretreated with melatonin. Radiation‐induced gastrointestinal DNA strand breaks, lipid peroxidation, and expression of proapoptotic‐p53, Bax, and antiapoptotic‐Bcl‐xL proteins were reversed in melatonin pretreated mice. This increase of Bcl‐xL was associated with the decrease of Bax/Bcl‐xL ratio. ABTS and DPPH radical assays revealed that melatonin treatment alleviated total antioxidant capacity in hematopoietic and gastrointestinal tissues. Present study demonstrated that melatonin pretreatment was able to prevent hematopoietic, immunological, and gastrointestinal radiation‐induced injury, therefore, overcoming lethality in mice. These results suggest potential of melatonin in developing radioprotector for protection of bone marrow, spleen, and gastrointestine in planned radiation exposure scenarios including radiotherapy. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 501–518, 2017.     

Effects of nano and conventional Zinc Oxide on anxiety-like behavior in male rats

Objectives:

Current drug therapies for psychological disorders, such as anxiety, are not as effective as expected, and it has been shown that zinc supplements, such as zinc oxide (ZnO), can influence anxiety. ZnO nanoparticles (ZnO NPs) are among the most used nanomaterials produced and applied in many products.

Materials and Methods:

This study investigated the effects of ZnO NPs in comparison with conventional ZnO (cZnO) on anxiety-like behaviors. Adult male Wistar rats were divided into groups: Control (receiving saline 0.9%), ZnO NPs (5, 10, 20 mg/kg), and cZnO (5, 10, 20 mg/kg). All drugs were dispersed in saline 0.9%, and 30 minutes after intraperitoneal (i.p.) injection of drugs, elevated plus maze apparatus was used to evaluate anxiety.

Results:

ZnO NPs (5 mg/kg) and cZnO (10 and 20 mg/kg) significantly increased the percentage of time spent in open arm (open arm time % OAT) compared with the control group (P < 0.05). This indicates the anxiolytic effect of such components; in addition, ZnO NPs (20 mg/kg) reduced locomotor activity (P < 0.05). Serum zinc concentration increased by both anxiolytic dose of components (from 1.75 ± 1.07 (mg/l) in control group to 5.31 ± 0.53 (mg/l) in ZnO NPs (5 mg/kg) and 10.38 ± 0.90 (mg/l) in cZnO (10 mg/kg) groups). Also, all doses increased serum pH (from 7.3 ± 0.05 in control group to 8.1 ± 0.05 in ZnO NPs (5 mg/kg) and 8.05 ± 0.01 in cZnO (10 mg/kg) groups and kept them constant after 24 hours.

Conclusion:

Results indicate that the anxiolytic effect of ZnO NPs is much higher than its conventional form, but the introduction of ZnO NPs, as a new drug for treatment of anxiety disorder, needs further investigations.KEY WORDS: Anxiety, Nano ZnO, plus maze, rat     

Effects of di(2‐ethylhexyl)phthalate on testicular oxidant/antioxidant status in selenium‐deficient and selenium‐supplemented rats

Di(ethylhexyl)phthalate (DEHP), the most widely used plasticizer, was investigated to determine whether an oxidative stress process was one of the underlying mechanisms for its testicular toxicity potential. To evaluate the effects of selenium (Se), status on the toxicity of DEHP was further objective of this study, as Se is known to play a critical role in testis and in the modulation of intracellular redox equilibrium. Se deficiency was produced in 3‐weeks‐old Sprague–Dawley rats feeding them ≤0.05 mg Se /kg diet for 5 weeks, and Se‐supplementation group was on 1 mg Se/kg diet. DEHP‐treated groups received 1000 mg/kg dose by gavage during the last 10 days of the feeding period. Activities of antioxidant selenoenzymes [glutathione peroxidase 1 (GPx1), glutathione peroxidase 4 (GPx4), thioredoxin reductase (TrxR)], catalase (CAT), superoxide dismutase (SOD), and glutathione S‐transferase (GST); concentrations of reduced glutathione (GSH), oxidized glutathione (GSSG), and thus the GSH/GSSG redox ratio; and thiobarbituric acid reactive substance (TBARS) levels were measured. DEHP was found to induce oxidative stress in rat testis, as evidenced by significant decrease in GSH/GSSG redox ratio (>10‐fold) and marked increase in TBARS levels, and its effects were more pronounced in Se‐deficient rats with ～18.5‐fold decrease in GSH/GSSG redox ratio and a significant decrease in GPx4 activity, whereas Se supplementation was protective by providing substantial elevation of redox ratio and reducing the lipid peroxidation. These findings emphasized the critical role of Se as an effective redox regulator and the importance of Se status in protecting testicular tissue from the oxidant stressor activity of DEHP. © 2011 Wiley Periodicals, Inc. Environ Toxicol 29: 98–107, 2014.     

Investigational New Drug‐Directed, 5‐Day Repeat Dose Toxicity Study of 4‐[3‐(2‐Nitro‐1‐Imidazolyl)‐Propylamino]‐7‐Chloroquinoline Hydrochloride (NLCQ‐1, NSC 709257) Administered with or without Taxol® in Sprague–Dawley Rats

Abstract: In pre‐clinical studies, 4‐[3‐(2‐nitro‐1‐imidazolyl)‐propylamino]‐7‐chloroquinoline hydrochloride (NLCQ‐1, NSC 709257) is a weak DNA‐intercalating, hypoxia‐selective cytotoxin with a promising profile as an adjuvant to radio/chemotherapy and it is about to enter phase I clinical trials. The present investigation was undertaken to further evaluate potential systemic toxicity induced by i.v. doses of NLCQ‐1 alone or in combination with Taxol ^® in Sprague–Dawley rats, in support of an investigational new drug application. Doses of NLCQ‐1 were based on previous range‐finding studies. In the present study, NLCQ‐1 was administered either alone, at 0, 6, 9 or 12 mg/kg/dose to male rats and 8, 12 or 16 mg/kg/dose to female rats or, at 9 (male rats) and 12 (female rats) mg/kg/dose, in combination with Taxol^®, on a qd × 5 schedule. Taxol^® was administered i.v. at 3.5 mg/kg/dose 1 hr before NLCQ‐1. Observations were recorded for mortality/moribundity, clinical signs of toxicity, body weights, food consumption, haematology, clinical chemistry, gross lesions at necropsy and histopathology. Blood samples were taken from 10 animals from each dose group on each of 2 days (days 8 and prior to scheduled necropsy on day 33). Administration of i.v. doses of NLCQ‐1 alone, on a qdx5 schedule, resulted in no signs of toxicity over the 33‐day study. Taxol^®‐induced toxicity included minimal decreases in the group mean RBC, haemoglobin and haematocrit values, minimal increases in group mean reticulocyte counts (females), marked decreases in group mean neutrophil counts and minimal decreases in group mean monocyte and eosinophil counts. Lymphoid atrophy of thymus, atrophy of bone marrow and atrophy of the germinal epithelium of the testis were also associated with the administration of Taxol^®. There was no additional toxicity associated with the co‐administration of NLCQ‐1 and Taxol^®. In the present study, the ‘no observable adverse effect level’ for NLCQ‐1, when administered on a qdx5 schedule, was >12 and >16 mg/kg/dose in male and female rats respectively. Daily administration of 9 (male rats) or 12 (female rats) mg/kg of NLCQ‐1 1 hr after i.v. administration of Taxol^® (3.5 mg/kg) had no effect on Taxol^®‐induced toxicity.     

Deep sea minerals ameliorate diabetic‐induced inflammation via inhibition of TNFα signaling pathways

It has been well‐documented that the consumption of deep sea water (DSW) has beneficial effects on myocardial hypertrophy and cardiac apoptosis induced by hypercholesterolemia. However, the molecular mechanisms for the anti‐inflammatory effects of DSW on diabetic cardiomyopathy are still largely unclear. The main purpose of this present study was to test the hypothesis that DSW exerts anti‐inflammatory effects through the suppression of the TNF‐α‐mediated signaling pathways. IP injection of streptozotocin (STZ) at the dose of 65 mg/kg was used to establish a diabetes rat model. DSW mineral extracts that diluted in desalinated water were prepared in three different dosages and administered to the rats through gavages for 4 weeks. These dosages are DSW‐1X (equivalent to 37 mg Mg²⁺/kg/day), 2X (equivalent to 74 mg Mg²⁺/kg/day) and 3X (equivalent to 111 mg Mg²⁺ mg/kg/day). Immunofluorescence staining and Western blot showed that the protein expression level of TNF‐α was markedly higher in the STZ‐induced diabetic rat hearts than in the control group. Consequently, the phosphorylation levels of the TNF‐α‐modulated downstream signaling molecules and P38 mitogen‐activated protein kinases (MAPKs) were notably elevated in heart tissues of STZ‐induced diabetes. These higher phosphorylation levels subsequently upregulated NF‐κB‐modulated inflammatory mediators, such as cyclooxygenase (COX)‐II and inducible nitric oxide synthase (iNOS). However, treatment with DSW as well as MgSO₄, the main mineral in DSW, significantly reversed all the alterations. These findings suggest that DSW has potential as a therapeutic agent for preventing diabetes‐related cardiovascular diseases.     

Phytotoxic and genotoxic effects of ZnO nanoparticles on garlic (Allium sativum L.): a morphological study

The effects of zinc oxide nanoparticles (ZnO NPs) on the root growth, root apical meristem mitosis and mitotic aberrations of garlic (Allium sativum L.) were investigated. ZnO NPs caused a concentration-dependent inhibition of root length. When treated with 50 mg/L ZnO NPs for 24 h, the root growth of garlic was completely blocked. The 50% inhibitory concentration (IC(50)) was estimated to be 15 mg/L. The mitosis index was also decreased in a concentration- and time-dependent manner. ZnO NPs also induced several kinds of mitotic aberrations, mainly consisted of chromosome stickiness, bridges, breakages and laggings. The total percentage of abnormal cells increased with the increase of ZnO NPs concentration and the prolongation of treatment time. The investigation provided new information for the possible genotoxic effects of ZnO NPs on plants.     

Role of betaine in liver injury induced by the exposure to ionizing radiation

Oxidative stress, apoptosis, and fibrosis may play a major role in the development of radiation‐induced liver damage. Betaine, a native compound widely present in beetroot, was reported to possess hepato‐protective properties. The objective of this study was to investigate the influence of betaine on radiation‐induced liver damage. Animals were exposed to 9 Gy applied in 3 doses of 3 Gy/wk. Betaine (400 mg/kg/d), was orally supplemented to rats after the first radiation dose, and daily during the irradiation period. Animals were sacrificed 1 day after the last dose of radiation. The results showed that irradiation has induced oxidative stress in the liver denoted by a significant elevation in malondialdehyde, protein carbonyl, and 8‐hydroxy‐2‐deoxyguanosine with a significant reduction in catalase activity and glutathione (GSH) content. The activity of the detoxification enzyme cytochrome P450 (CYP450) increased while GSH transferase (GSH‐T) decreased. The activity of the apoptotic marker caspase‐3 increased concomitant with increased hyaluronic acid, hydroxyproline, laminin (LN), and collagen IV. These alterations were associated with a significant increase of gamma‐glutamyl transferase, alkaline phosphatase and alanine and aspartate aminotransferase markers of liver dysfunction. Betaine treatment has significantly attenuated oxidative stress, decreased the activity of CYP450, enhanced GSH‐T, reduced the activity of caspase‐3, and the level of fibrotic markers concomitant with a significant improvement of liver function. In conclusion, betaine through its antioxidant activity and by enhancing liver detoxification and reducing apoptosis may alleviate the progression of liver fibrosis and exert a beneficial impact on radiation‐induced liver damage.     

Copper nanoparticle‐induced uterine injury in female rats

Copper nanoparticles (Cu‐NPs) have been used increasingly in various products and applications. Although recent studies have reported that exposure to Cu‐NPs leads to organ accumulation and obvious toxicity, it remains unclear whether Cu‐NPs can be translocated to and cause damage in the uterus. In this study, we investigated the potential for uterine injury and gene expression patterns in female rats exposed to 3.12, 6.25, or 12.5 mg/kg/d Cu‐NPs via intraperitoneal injection for 14 consecutive days. The results indicated that exposure to Cu‐NPs led to significant decreases in the relative uterine weight coefficients and increases in inflammatory cell infiltration, mitochondrial swelling and vacuolization, shortened and reduced endometrial epithelial cell microvilli, and apoptosis. Furthermore, exposure to Cu‐NPs increased malondialdehyde (MDA) accumulation and decreased superoxide dismutase (SOD) levels. Signal transduction mechanism studies indicated that exposure to Cu‐NPs activated caspases 3, 8, and 9 and BH3 interacting domain death agonist (tBid), reduced B cell leukemia/lymphoma 2 (Bcl‐2) expression, and increased the expression of apoptotic peptidase activating factor 1 (Apaf‐1), BCL2‐associated X, apoptosis regulator (Bax), and cytochrome c. A microarray analysis revealed significant alterations in the expression of 963 genes; of these, 622 were upregulated and 341 were downregulated. The results of further evaluations of some altered genes, including matrix metallopeptidase 12 (Mmp12), using quantitative RT‐PCR agreed with the microarray findings. These results provide strong evidence that Cu‐NPs can trigger both intrinsic and extrinsic apoptotic pathways to mediate uterine injury, resulting in oxidative stress‐related changes in gene expression.     

Counteraction of the Rapid Tolerance to 8‐Hydroxy‐2‐(di‐n‐propylamino)tetralin‐Induced Hypothermia in Rats by Activation of the GABAA Receptor‐Chloride Channel Complex

Abstract: The effects of compounds that open the GABA_A receptor‐chloride channel complex on the rapidly developed tolerance to the 8‐hydroxy‐2‐(di‐n‐propylamino)tetralin hydrobromide(8‐OH‐DPAT)‐induced hypothermia in rats were examined. The test compound was injected 15 min. before 1 mg/kg subcutaneous 8‐OH‐DPAT or saline and 24 hr later a challenge dose of 0.1 mg/kg subcutaneous 8‐OH‐DPAT was given. The rectal temperature was measured before the challenge dose and 30, 60, 90 and 120 min. thereafter. The hypothermic effect was calculated as the area under the curve. It was found that all the GABAergic compounds examined significantly counteracted the 8‐OH‐DPAT‐induced tolerance to the hypothermic response: muscimol at 3 mg/kg subcutaneous, diazepam at 1 – 3 mg/kg subcutaneous, pentobarbitone sodium at 20 mg/kg subcutaneous, and chlormethiazole at 40 mg/kg subcutaneous. Combined treatment of the rats with the GABA_A receptor antagonist, bicucculine, or the GABA_A receptor‐chloride channel blocker, picrotoxin and diazepam, pentoparbitone sodium or chlormethiazole significantly antagonised this counteraction of the 8‐OH‐DPAT‐induced tolerance. Depletion of 5‐HT by pretreatment of the rats with the tryptophan hydroxylase inhibitor p‐chlorophenylalanine did not counteract the 8‐OH‐DPAT‐induced tolerance to the hypothermic response. Pretreatment of the rats with dexamethazone did not change the development of the tolerance to 8‐OH‐DPAT‐induced hypothermic effect which seems to exclude the involvement of the hypothalamo‐pituitary‐adrenocortical axis in the tolerance development. It is concluded that the results support the hypothesis that GABA neurones beyond the 5‐HT neurones are involved in the mechanism causing tolerance to the 5‐HT_1A receptor‐mediated hypothermia in rats.     

Toxic effects of methamidophos on paraoxonase 1 activity and on rat kidney and liver and ameliorating effects of alpha‐tocopherol

The role of alpha‐tocopherol on nephrotoxicity and hepatotoxicity induced by methamidophos (MT) was investigated in wistar rats. Animals were given via gavage, for four weeks, a low dose of MT (MT1), a high dose of MT (MT2), vitamin E (200 mg/kg of bw) or both MT2 plus vitamin E (Vit E) and control group was given distillate water. MT treatment resulted in a significant decrease in the body weight of MT2‐treated group. Moreover, MT‐treated groups had significantly lower butyrylcholinesterase (p < 0.01) and paraoxonase 1 (PON1) activities compared with the control group (p < 0.05). However, MT2‐treated group had significantly higher alkaline phosphatase activity compared with untreated rats (p < 0.05). Both MT‐treated groups had significantly higher urea (p < 0.01) and uric acid levels (p < 0.05) compared with the control group. However, significant low uric acid level (p < 0.05) was noted in MT2 plus vit E‐treated rats compared with MT2‐treated group. Histopathological changes in organ tissues were observed in both MT‐treated groups and MT2 plus vit E‐treated rats. However, the damage was reduced in MT2 plus vit E‐treated rats. Therefore, this study deduces that alpha‐tocopherol administration may ameliorate the adverse effects of subacute exposure to MT on rat liver and kidney and this antioxidant can protect PON1 from oxidative stress induced by this organophosphorus pesticide. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 842–854, 2016.