Intratracheal exposure to multi-walled carbon nanotubes induces a nonalcoholic steatohepatitis-like phenotype in C57BL/6J mice

Abstract

The effects of multi-walled carbon nanotubes (MWCNTs) exposure have garnered great interest in the field of public health, due to the high aspect ratio of MWCNTs. Because of worldwide increases in obesity prevalence, nonalcoholic fatty liver disease (NAFLD) is now the most common prevalent liver disease and is considered to be a component of metabolic syndrome, which is a cluster of disorders that also includes dyslipidemia, diabetes mellitus, arteriosclerosis, and hypertension. Exposure to MWCNTs is known to be a risk factor for lung and cardiovascular diseases, but its effect on NAFLD is unknown. In this study, we investigated the effects of intratracheal exposure of two different types of MWCNTs, namely, pristine multi-walled carbon nanotubes (PMWCNTs) and acid-treated multi-walled carbon nanotubes (TMWCNTs), on liver pathogenesis. Direct instillation of a test material into the lungs has been employed as a quantitatively reliable alternative method of inhalation exposure. The 10% weight loss dose was assessed in three months of subchronic study and is defined here as the maximum tolerated dose (MTD) of PMWCNTs and TMWCNTs; by this metric, MTD for a 1-year exposure of MWCNTs was determined to be 0.1?mg/mouse. Mice exposed to PMWCNTs and TMWCNTs for one year developed a nonalcoholic steatohepatitis (NASH)-like phenotype, characterized by inflammation, hepatic steatosis, and fibrosis. Furthermore, PMWCNTs induced a more severe NASH-like phenotype than TMWCNTs, which was related to consistent up-regulation of interleukin (IL)-6 and plasminogen activator inhibitor (PAI)-1. Impaired cholesterol homeostasis, overexpression of NF-κBp65, and suppression of peroxisome proliferator-activated receptor gamma (PPARγ) in the liver were also observed.     

Macrophage polarization and activation at the interface of multi-walled carbon nanotube-induced pulmonary inflammation and fibrosis

Pulmonary exposure to carbon nanotubes (CNTs) induces fibrosing lesions in the lungs that manifest rapid-onset inflammatory and fibrotic responses, leading to chronic fibrosis in animals and health concerns in exposed humans. The mechanisms underlying CNT-induced fibrogenic effects remain undefined. Macrophages are known to play important roles in immune regulation and fibrosis development through their distinct subsets. Here we investigated macrophage polarization and activation in mouse lungs exposed to multi-walled CNTs (MWCNTs). Male C57BL/6J mice were treated with MWCNTs (XNRI MWNT-7) at 40?μg per mouse (～1.86?mg/kg body weight) by oropharyngeal aspiration. The treatment stimulated prominent acute inflammatory and fibrotic responses. Moreover, it induced pronounced enrichment and polarization of macrophages with significantly increased M1 and M2 populations in a time-dependent manner. Induction of M1 polarization was apparent on day 1 with a peak on day 3, but declined rapidly thereafter. On the other hand, the M2 polarization was induced on day 1 modestly, but was remarkably elevated on day 3 and maintained at a high level through day 7. M1 and M2 macrophages were functionally activated by MWCNTs as indicated by the expression of their distinctive functional markers, such as iNOS and ARG1, with time courses parallel to M1 and M2 polarization, respectively. Molecular analysis revealed MWCNTs boosted specific STAT and IRF signaling pathways to regulate M1 and M2 polarization in the lungs. These findings suggest a new mechanistic connection between inflammation and fibrosis induced by MWCNTs through the polarization and activation of macrophages during MWCNT-induced lung pathologic response.     

Toward safer multi-walled carbon nanotube design: Establishing a statistical model that relates surface charge and embryonic zebrafish mortality

Given the increased utility and lack of consensus regarding carbon nanotube (CNT) environmental and human health hazards, there is a growing demand for guidelines that inform safer CNT design. In this study, the zebrafish (Danio rerio) model is utilized as a stable, sensitive biological system to evaluate the bioactivity of systematically modified and comprehensively characterized multi-walled carbon nanotubes (MWNTs). MWNTs were treated with strong acid to introduce oxygen functional groups, which were then systematically thermally reduced and removed using an inert temperature treatment. While 25 phenotypic endpoints were evaluated at 24 and 120 hours post-fertilization (hpf), high mortality at 24?hpf prevented further resolution of the mode of toxicity leading to mortality. Advanced multivariate statistical methods are employed to establish a model that identifies those MWNT physicochemical properties that best estimate the probability of observing an adverse outcome. The physicochemical properties considered in this study include surface charge, percent surface oxygen, dispersed aggregate size and morphology and electrochemical activity. Of the five physicochemical properties, surface charge, quantified as the point of zero charge (PZC), was determined as the best predictor of mortality at 24?hpf. From a design perspective, the identification of this property–hazard relationship establishes a foundation for the development of design guidelines for MWNTs with reduced hazard.     

Mapping differential cellular protein response of mouse alveolar epithelial cells to multi-walled carbon nanotubes as a function of atomic layer deposition coating

Carbon nanotubes (CNTs), a prototypical engineered nanomaterial, have been increasingly manufactured for a variety of novel applications over the past two decades. However, since CNTs possess fiber-like shape and cause pulmonary fibrosis in rodents, there is concern that mass production of CNTs will lead to occupational exposure and associated pulmonary diseases. The aim of this study was to use contemporary proteomics to investigate the mechanisms of cellular response in E10 mouse alveolar epithelial cells in vitro after exposure to multi-walled CNTs (MWCNTs) that were functionalized by atomic layer deposition (ALD). ALD is a method used to generate highly uniform and conformal nanoscale thin-film coatings of metals to enhance novel conductive properties of CNTs. We hypothesized that specific types of metal oxide coatings applied to the surface of MWCNTs by ALD would determine distinct proteomic profiles in mouse alveolar epithelial cells in vitro that could be used to predict oxidative stress and pulmonary inflammation. Uncoated (U)-MWCNTs were functionalized by ALD with zinc oxide (ZnO) to yield Z-MWCNTs or aluminum oxide (Al₂O₃) to yield A-MWCNTs. Significant differential protein expression was found in the following critical pathways: mTOR/eIF4/p70S6K signaling and Nrf-2 mediated oxidative stress response increased following exposure to Z-MWCNTs, interleukin-1 signaling increased following U-MWCNT exposure, and inhibition of angiogenesis by thrombospondin-1, oxidative phosphorylation, and mitochondrial dysfunction increased following A-MWCNT exposure. This study demonstrates that specific types of metal oxide thin film coatings applied by ALD produce distinct cellular and biochemical responses related to lung inflammation and fibrosis compared to uncoated MWCNT exposure in vitro.     

Curcumin ameliorates experimental autoimmune encephalomyelitis in a C57BL/6 mouse model

Multiple sclerosis (MS) is a common inflammatory disease of the central nervous system. Although the exact etiology of the disease is largely unknown, it is identified that cytokines may play an important role in the pathogenesis of MS. In this study, the effects of curcumin has been investigated on the expression levels of selected cytokine coding genes as well as the extent of demyelination in the corpus callosum of C57BL/6 experimental autoimmune encephalomyelitis (EAE) model of MS. Gene expression analyses revealed that treatment with curcumin could lead to a significant reduction in the expression levels of pro-inflammatory cytokine coding genes including IL-6 (p = 0.001), IL-17 (p = 0.001), tumor necrosis factor (TNF)-α (p = 0.008), and interferon (IFN)-γ (p = 0.033) as well as a significant increase in the expression level of transforming growth factor (TGF)-β (p = 0.006) as an anti-inflammatory cytokine. Moreover, the expression of glutathione peroxidase (GPX)-1 gene and the activity of anti-oxidant enzymes were significantly higher (p < 0.001) in curcumin-treated mice. Luxol fast blue staining also confirmed a significant reduction in the extent of demyelination in the curcumin-treated group (p < 0.001). Our results have confirmed that curcumin is an effective therapeutic agent that could ameliorate the severity of EAE.     

Effect of surface functionalizations of multi-walled carbon nanotubes on neoplastic transformation potential in primary human lung epithelial cells

Functionalized multi-walled carbon nanotube (fMWCNT) development has been intensified to improve their surface activity for numerous applications, and potentially reduce toxic effects. Although MWCNT exposures are associated with lung tumorigenesis in vivo, adverse responses associated with exposure to different fMWCNTs in human lung epithelium are presently unknown. This study hypothesized that different plasma-coating functional groups determine MWCNT neoplastic transformation potential. Using our established model, human primary small airway epithelial cells (pSAECs) were continuously exposed for 8 and 12?weeks at 0.06?μg/cm² to three-month aged as-prepared-(pMWCNT), carboxylated-(MW-COOH), and aminated-MWCNTs (MW-NH_x). Ultrafine carbon black (UFCB) and crocidolite asbestos (ASB) served as particle controls. fMWCNTs were characterized during storage, and exposed cells were assessed for several established cancer cell hallmarks. Characterization analyses conducted at 0 and 2 months of aging detected a loss of surface functional groups over time due to atmospheric oxidation, with MW-NH_x possessing less oxygen and greater lung surfactant binding affinity. Following 8?weeks of exposure, all fMWCNT-exposed cells exhibited significant increased proliferation compared to controls at 7 d post-treatment, while UFCB- and ASB-exposed cells did not differ significantly from controls. UFCB, pMWCNT, and MW-COOH exposure stimulated significant transient invasion behavior. Conversely, aged MW-NH_x-exposed cells displayed moderate increases in soft agar colony formation and morphological transformation potential, while UFCB cells showed a minimal effect compared to all other treatments. In summary, surface properties of aged fMWCNTs can impact cell transformation events in vitro following continuous, occupationally relevant exposures.     

Testing anxiolytic drugs in the C57BL/6J mouse strain

C57BL/6J mice are one of the most commonly used mouse strains in biobehavioral and psychopharmacological research. Prone to variance due to multiple environmental factors, animal neurophenotyping studies rely on using proper experimental protocols, study designs and well-established models and tests. Choosing the dose range for anxiolytic or anxiogenic drugs is key for obtaining valid testing results and correct data interpretation. Here we emphasize the importance of accurate dose selection in rodent anxiety paradigms for concluding whether the mouse strain used is “sensitive” and therefore appropriate for studying anxiety in selected behavioral tests. We also provide further argument in support of using the C57BL/6J mouse strain for testing anxiolytic and anxiogenic compounds.     

C57BL/6小鼠在烧伤及药理学实验中的Meeh常数取值

目的研究在烧伤及药理学实验中计算C57BL/6小鼠全身体表面积(BSA)时Meeh常数(k)的取值。方法测量20只C57BL/6小鼠的体重和BSA,并计算出小鼠的实际k值,比较其与5个正常小鼠常用k值(6.0、9.1、9.5、10.0和11.4)间的差异。结果小鼠BSA计算所得的k值为9.715±0.142,与正常小鼠常用k值比较差异均有统计学意义(P<0.01)。结论应用Meeh公式计算C57BL/6小鼠的BSA时,k值宜选用9.715。     

Effect of traxanox on antibody formation in C57BL/6 mice

C57BL/6 mice, lower responders to sheep red blood cells (SRBC), were intraperitoneally immunized with 5 X 10(8) SRBC on day 0. Traxanox (10 and 30 mg/kg) administered orally on days 0 and 1 potentiated the production of spleen- and thymus-rosette forming cells (RFC) assessed on day 7. The production of hemolytic plaque forming cells (HPFC) to SRBC in the spleen of the syngeneic recipient mice assessed on day 4 was inhibited by the transfer of spleen-RFC obtained from the vehicle-treated donor mice, but not by that obtained from the traxanox (30 mg/kg)-treated donor mice. The same results were obtained in the thymectomized-recipient mice. The activity of the spleen-RFC obtained from the vehicle-treated donor mice was abolished by treatment with anti-Thy 1.2 or anti-Lyt 2.2 antibody and complement. On the other hand, the activity of the spleen-RFC obtained from the traxanox-treated donor mice was abolished by treatment with anti-Lyt 1.2 antiserum and complement. Traxanox (3 and 30 mg/kg) also caused the induction of the Thy 1.2-positive RFC in the spleen of the thymectomized mice. These results suggest that traxanox has a capacity to potentiate the immune responses to SRBC in C57BL/6 mice by the induction of Lyt 1.2-positive cells (helper T cells).     

Neuroprotection in the MPTP Parkinsonian C57BL/6 mouse model by a compound isolated from tobacco

Epidemiological evidence suggests a lower incidence of Parkinson's disease in smokers than in nonsmokers. This evidence, together with the lower levels of brain monoamine oxidase (MAO) activity in smokers and the potential neuroprotective properties of MAO inhibitors, prompted studies which led to the isolation and characterization of 2,3,6-trimethyl-1,4-naphthoquinone (TMN), an MAO-A and MAO-B inhibitor which is present in tobacco and tobacco smoke. Results of experiments reported here provide evidence that this compound protects against the MPTP-mediated depletion of neostriatal dopamine levels in the C57BL/6 mouse. These results support the hypothesis that the inhibition of MAO by constituents of tobacco smoke may be related to the decreased incidence of Parkinson's disease in smokers.     

Limitations on the use of the C57BL/6 mouse in the tail suspension test

RATIONALE: The C57BL/6 is one of the most widely used mouse strains in behavioral, pharmacological, and genetic research but little is known about their response on tests for antidepressant drugs. OBJECTIVES: The behavior of C57BL/6 mice, and mice from other strains, was examined in the tail suspension test (TST), a common behavioral test used for the screening of antidepressant compounds. METHODS: C57BL/6J mice from the Jackson Laboratory, C57BL/6N mice from Harlan, A/J, 129-SV-ter and DBA/2 mice were tested under baseline conditions in the TST. RESULTS: The majority of the C57BL/6 mice from the Jackson Laboratory tested in this paradigm (70%) climbed up their tails during the 6-min test session. C57BL/6 mice obtained from Harlan (35%) also demonstrated this climbing behavior, suggesting that it is not specific to mice from a particular supplier. Other strains (A/J 18%), 129-SV-ter (0%) and DBA/2 (0%) mice) showed less propensity for tail climbing. CONCLUSIONS: The occurrence of this behavior is an important consideration when testing antidepressant drugs or the effects of stress using the TST with inbred mouse strains, especially those from the C57BL/6 strain.     

C57BL/6小鼠幽门螺杆菌感染胃炎模型的复制

目的建立C57BL/6小鼠幽门螺杆菌(HP)感染动物模型,为进一步对HP进行相关研究奠定基础。方法清洁级环境中饲养C57BL/6小鼠88只,雌雄各半,随机分成三组:模型组40只、培养基组40只、空白对照组8只。模型组预先用NaHCO3处理后,再灌胃HP标准菌株SS1,隔天1次,共灌胃5次,于末次灌胃HP后2、4、6、8周分批处死,取胃黏膜组织,行快速尿素酶实验、HE染色及Warthin-Starry银染,观察HP在小鼠胃内定植及胃黏膜病理组织学变化情况。结果模型组末次灌胃2周后胃黏膜即有HP定植,2、4、6、8周小鼠HP的感染率分别为30%、50%、70%、90%,四组感染率比较差异有统计学意义(P<0.05);空白对照组与培养基组小鼠胃黏膜炎症评分差异无统计学意义(P=0.712),空白对照组与模型组炎症评分比较差异均有统计学意义(P=0.000),培养基组与模型组炎症评分比较差异均有统计学意义(P=0.000);模型组灌胃后2周、4周、6周、8周胃黏膜炎症评分比较差异均有统计学意义(P<0.05)。模型组2周、4周、6周、8周各组感染HP定植评分比较,差异有统计学意义(P<0.05,P=0.000)。结论通过将HP标准菌株SS1灌服给预先用碱处理的C57BL/6小鼠,复制了小鼠HP感染模型,引起小鼠胃黏膜病理改变,随灌胃HP时间延长,感染率增加,胃黏膜炎症严重程度增加,HP定植逐渐增多。     

The increases in relative mRNA expressions of inflammatory cytokines and chemokines in splenic macrophages from rats exposed to multi-walled carbon nanotubes by whole-body inhalation for 13 weeks

Abstract

Background: The toxicity of multi-walled carbon nanotubes (MWCNT) may be related to the immune system. The objective of this study was to obtain information for immunotoxic mechanisms of MWCNT in situ.

Methods: Using whole-body inhalation, male and female rats were exposed to 0, 0.2, 1 or 5?mg MWCNT/m³ for 13 weeks. Thereafter, spleens were recovered from the rats. Real-time PCR was done to assess expression of TNFα, IL-1β, IL-6, IL-10, MCP-1 and MIP-1α mRNA in the splenic macrophages; splenic T-lymphocytes were examined for IL-2 and TGF-β₁ mRNA expression.

Results: The relative expression of IL-1β mRNA in the cells from female rats exposed to 5?mg MWCNT/m³ was significantly higher than that in control cells. For IL-6 and IL-10, cells from rats in the 0.2 and 5?mg MWCNT/m³ had significantly higher mRNA expressions than did cells from controls. Expression of IL-1β, IL-6 and TNFα genes in cells from males in all exposure groups were higher than in control cells. Expression of MIP-1α in the cells from female 5-mg group was significantly higher than that in cells in the control. Only IL-2 was expression reduced, i.e. cells from male and female rats in all MWCNT groups had significantly lower mRNA expressions than control cells.

Conclusions: Systemic inflammation would likely occur in rats (or other hosts) exposed to MWCNT via inhalation due to increases in the expression of inflammatory cytokines in splenic macrophages. Moreover, decreases in IL-2 expression in T-lymphocytes may be critical to the potential reductions in anti-tumor responses in MWCNT-exposed hosts.     

Parkinsonian rotenone mouse model: reevaluation of long-term administration of rotenone in C57BL/6 mice

Chronic systemic exposure of Lewis rats to rotenone produced many features of Parkinson's disease (PD), including nigrostriatal dopamine (DA) neurodegeneration and the formation of cytoplasmic inclusions in nigral DA neurons. We also reported that chronic oral administration of rotenone at 30 mg/kg for 28 d caused specific nigrostriatal DA neurodegeneration in C57BL/6 mice. To establish a PD model more suitable for evaluating nigrostriatal DA neurodegeneration, the present study has been designed to assess the neurotoxicity of rotenone after daily oral administration at 30 or 100 mg/kg for 56 d in C57BL/6 mice. The survival rate of rotenone-treated mice at 30 mg/kg did not change from 28 to 56 d, although the survival rate of rotenone-treated mice at 30 mg/kg was decreased to about 70% within one week. The survival rate of the rotenone-treated mice at 100 mg/kg was suddenly decreased after 28 d, and finally to about 15% at 56 d. Rotenone at 30 mg/kg, but not 100 mg/kg, for 28 d caused a significant loss of tyrosine hydroxylase (TH)-positive neurons in the substantia nigra. Rotenone at 100 mg/kg caused a highly variable loss of TH-positive neurons among individual mice. Rotenone at 30 mg/kg for 56 d caused a significant loss of TH-positive neurons and behavioral impairment. In addition, α-synuclein immunoreactivity was increased in surviving TH-positive neurons in a time-dependent manner. Thus, this protocol for chronic administration of rotenone at 30 mg/kg for 56 d is more useful for understanding the mechanism of DA neurodegeneration.     

Effect of ketamine on exploratory behaviour in BALB/C and C57BL/6 mice

In this study, we evaluated the effect of ketamine on exploratory locomotion behaviours in the Balb/c and C57BL/6 strains of mice, which differ in their locomotion behaviours.Intraperitoneal administration of ketamine at three different doses (1, 5 or 10 mg/kg, 0.1 ml/10 gr body weight) was performed on adult male Balb/c and C57BL/6 mice. The same volume of saline was applied to the control group. The open-field and elevated plus maze apparatus were used to evaluate exploratory locomotion.In the open-field test, Balb/c mice less spend time in the centre of the field and was decreased locomotor activity compared to C57BL/6 mice (p < 0.01). Ketamine treatment of Balb/c mice at 10 mg/kg dose caused an increase in locomotor activity and an increase in the amount of time spent in the centre in the open-field test, compared to the control group (p < 0.05). In C57BL/6 mice, ketamine treatment (1 and 10 mg/kg) decreased locomotor activity (p < 0.05). In C57BL/6 mice, the three different doses of ketamine application each caused a decrease in the frequency of centre crossing (p < 0.001) and the spent time in the centre (p < 0.05).In the elevated plus maze, the number of open-arm entries, the percentage of open-arm time and total arm entries were decreased in Balb/c mice compared to C57BL/6 mice (p < 0.001). Ketamine treatment of Balb/c mice at 10 mg/kg dose caused an increase in the open-arm activity (p < 0.001). Ketamine application (10 mg/kg) decreased the open-arm activity in C57BL/6 mice (p < 0.05).A subanaesthetic dose of ketamine increased exploratory locomotion in Balb/c mice. In contrast, a subanaesthetic dose of ketamine decreased exploratory locomotion in C57BL/6 mice. In conclusion, hereditary factors may play an important role in ketamine-induced responses.     

Effect of some antipsychotic drugs on immunoreactivity in C57BL/6 mice

The study examined the effect of some typical and atypical antipsychotic drugs on mouse lymphocyte metabolic and proliferative activity in vitro. The typical antipsychotic drug chlorpromazine (3 x 10(-6), 10(-5) and 10(-4) M), significantly inhibited 3H-thymidine incorporation into C57BL/6 mouse spleen cells stimulated by concanavalin A (Con A), lipopolysaccharide (LPS) or pokeweed mitogen (PWM). Chlorpromazine at concentrations of 10(-5) and 10(-4) M also suppressed the metabolic activity of splenocytes after Con A stimulation. The atypical antipsychotic agent clozapine (10(-4) and 10(-5) M) decreased the proliferative activity of splenocytes after LPS stimulation, but its inhibitory effect after Con A was observed only at higher concentrations. On the other hand, clozapine did not affect the metabolic activity of splenocytes. Sulpiride, a selective dopamine D2 antagonist, at concentrations ranging from 10(-8) to 10(-4) M had no inhibitory effect on the proliferative or metabolic activity of the tested cells. The obtained results indicate that of the three antipsychotic drugs studied, chlorpromazine shows the most potent immunosuppressive effect, clozapine produces a moderate effect and sulpiride is totally inactive. These findings suggest that the choice of antipsychotic drugs should also depend on disturbance of immune system activity, in particular, those occurring in the several forms of psychosis.     

Analysis of pulmonary surfactant in rat lungs after intratracheal instillation of short and long multi-walled carbon nanotubes

Abstract

Multi-walled carbon nanotubes (MWCNTs) are interesting new materials, but there is some concern about their harmfulness due to their fibrous nature. To determine the difference in the biological effects of MWCMTs by fiber length, we prepared two MWCNT samples from one bulk sample. One consisted of cut up short fibers (Short; average length?=?0.94?µm) and the other was just dispersed (Long; average length?=?3.4?µm). The samples were administered to male Wistar rats by intratracheal instillation at doses of 0.2?mg and 1?mg/animal (Short) and 0.2?mg and 0.6?mg/animal (Long). The animals were sacrificed at time points from 3?d to 12 months after administration. Bronchoalveolar lavage fluid (BALF) was taken from the lungs and pathological specimens were prepared. The concentrations of phospholipids, total protein and surfactant protein D (SP-D) in the pulmonary surfactant of the BALF were determined, the surface tension of BALF was measured, and the inflammation score was determined by the point-counting method to assess pulmonary tissue inflammation. The present study suggests that inflammatory response in the lung was slightly higher for long MWCNTs than for short MWCNTs when compared at the same mass dose. The correlation between pulmonary surfactant components and BALF surface tension was also evaluated. The Spearman’s rank correlation coefficients obtained for the phospholipid, total protein and SP-D concentrations were ?0.068 (p?=?0.605), ?0.360 (p?=?0.005) and ?0.673 (p?=?0.000), respectively. Surface tension, measured by a simple method, should be reflected in the change of a surfactant protein, such as SP-D.     

Social model of depression in mice of C57BL/6J strain

Long experience of defeat in daily social intermale confrontations and permanent living with aggressive males under sensory contact conditions [Kudryavtseva (8)] has been shown to produce changes in the patterns of submissive behavior of male mice of C57BL/6J strain. The submissive males after 20 defeats demonstrated passive defense postures instead of active defense and withdrawal which they had displayed in first encounters. Moreover, new immobile postures appeared, which were very rare in the first confrontations. Submissive animals displayed a decrease of ambulation in the open-field test and increase the immobility time in the Porsolt's test. Chronic treatment with imipramine prevented the increase of "depressiveness" estimated by means of the Porsolt's test. There was a loss of weight and some disturbances in gastrointestinal functions. The data are discussed in terms of the development of depression in submissive male C57BL/6J mice as a result of chronic unavoidable social stress.     

C57BL/6J小鼠颈动脉粥样硬化斑块模型的建立

目的 探讨一种经济快速制作颈动脉粥样硬化斑块的方法.方法 30只C57BL/6J小鼠随机分为实验组(A组,24只)和对照组(C组,6只).A组采用颈动脉硅胶圈植入法建立颈动脉粥样硬化斑块模型.术后0、2、4、6周,检测甘油三酯(TG)、血清总胆固醇(TC)、低密度脂蛋白(LDL)及高密度脂蛋白(HDL)水平,HE染色检测颈动脉病理形态学的变化.结果 与C组相比,A组小鼠TC及LDL水平升高(P＜0.05),HDL水平降低(P＜0.05),小鼠淋巴细胞广泛浸润,内膜、中膜增厚,颈动脉斑块形成.结论 采用颈动脉硅胶圈植入法可快速制作C57BL/6J小鼠颈动脉粥样硬化斑块模型.     

Early chronic lead exposure reduces exploratory activity in young C57BL/6J mice

Research has suggested that chronic low‐level lead exposure diminishes neurocognitive function in children. Tests that are sensitive to behavioral effects at lowest levels of lead exposure are needed for the development of animal models. In this study we investigated the effects of chronic low‐level lead exposure on exploratory activity (unbaited nose poke task), exploratory ambulation (open field task) and motor coordination (Rotarod task) in pre‐adolescent mice. C57BL/6J pups were exposed to 0 ppm (controls), 30 ppm (low‐dose) or 230 ppm (high‐dose) lead acetate via dams’ drinking water administered from birth to postnatal day 28, to achieve a range of blood lead levels (BLLs) from not detectable to 14.84 µg dl^–1). At postnatal day 28, mice completed behavioral testing and were killed (n = 61). BLLs were determined by inductively coupled plasma mass spectrometry. The effects of lead exposure on behavior were tested using generalized linear mixed model analyses with BLL, sex and the interaction as fixed effects, and litter as the random effect. BLL predicted decreased exploratory activity and no threshold of effect was apparent. As BLL increased, nose pokes decreased. The C57BL/6J mouse is a useful model for examining effects of early chronic low‐level lead exposure on behavior. In the C57BL/6J mouse, the unbaited nose poke task is sensitive to the effects of early chronic low‐level lead exposure. This is the first animal study to show behavioral effects in pre‐adolescent lead‐exposed mice with BLL below 5 µg dl^–1. Copyright © 2014 John Wiley & Sons, Ltd.