BackgroundGiven the global aging trend and the rising challenge of Alzheimer's disease (AD), accumulating evidence identifies cerebral microvascular dysfunction as an early pathological event. Hence, elucidating the key molecular regulators of cerebral microvascular function is critical for developing early intervention strategies.ObjectiveTo identify key genes associated with cerebral microvascular dysfunction in early-stage AD based on transcriptomics and to investigate the competing endogenous RNA (ceRNA) network involving long non-coding RNA (lncRNA).MethodsImmunofluorescence staining for CD31 was conducted on cerebral cortical sections from 1-month-old APP/PS1 and wild-type (WT) mice. Cerebral cortex and microvascular fractions were isolated for qPCR and western blot analysis of microvascular functional molecules. Following differential expression analysis, we performed functional and pathway enrichment, PPI network construction, ClueGo module analysis, and CFG prioritization to screen for core genes regulating cerebral microvascular function. A comprehensive ceRNA network was then established by integrating multi-database miRNA target predictions with RNA expression correlation data.ResultsOne-month-old AD mice exhibited both reduced cerebral microvascular density and average vessel length, along with significant disruption in the expression of blood-brain-barrier proteins. Transcriptomic profiling identified 956 differentially expressed transcripts, including 539 lncRNAs, 412 mRNAs, and 5 miRNAs. By integrative bioinformatics analysis, we identified 11 hub genes primarily involved in vascular contraction and circadian regulation, and constructed a comprehensive ceRNA network comprising 7 mRNAs, 41 miRNAs, and 46 lncRNAs.ConclusionsOur results reveal that early-stage AD is characterized by cerebral microvascular dysfunction, primarily mediated through impaired vascular contraction and disrupted circadian rhythm regulation.

Background: There is limited information about gene-environment interaction on the occurrence and the progression of Alzheimer’s disease. Objective: To explore the effect of environmental low-dose cadmium (Cd) exposure on the progress of Alzheimer’s disease and the underlining mechanism. Methods: We administered 1 mg/L, 10 mg/L cadmium chloride (treated groups), and water (control group) to C57BL/6J and APP/PS1 mice through drinking water, from one week before mating, until the offspring were sacrificed at 6 months of age. The behaviors, Cd level, blood-brain barrier (BBB) leakage, Aβ1-42 deposition, and inflammation expression were evaluated in these mice. Results: Mice of both genotypes had similar blood Cd levels after exposure to the same dose of Cd. The toxic effects of Cd on the two genotypes differed little in terms of neuronal histomorphology and BBB permeability. Cd caused a series of pathological morphological changes in the mouse brains and more fluorescent dye leakage at higher doses. Furthermore, the APP/PS1 mice had more severe damage than the C57BL/6J mice, based on the following five criteria. They were increasing anxiety-like behavior and chaos movement, spatial reference memory damage, Aβ plaque deposition in mouse brains, increasing microglia expression in the brain, and IL-6 higher expression in the cortex and in the serum. Conclusion: Low-dose Cd exposure for 6 months increases Aβ plaque deposition and BBB permeability, exacerbates inflammatory responses, and activates microglia, in APP/PS1 mice. APP/PS1 gene-environmental Cd interaction aggravates the progression of Alzheimer’s disease in mice.

Nano-SiO2 is increasingly used in diagnostic and biomedical research because of its ease of production and relatively low cost and which is generally regarded as safe and has been approved for use as a food or animal feed ingredient. Although recent literature reveals that nano-SiO2 may present toxicity and DNA damage, however, the underlying mechanism remains poorly understood. Since in previous studies, we found that nano-SiO2 treatment down-regulated the expression of the poly(ADP-ribose) polymerases-1 (PARP-1), a pivotal DNA repair gene, in human HaCaT cells and PAPR-1 knockdown can aggravate DNA damage induced by nano-SiO2 . Therefore, we speculate whether PARP-1 overexpression can protect DNA from damage induced by nano-SiO2 . However, our data demonstrated that overexpression of PARP-1 in HaCaT cells slightly enhanced the cellular proliferation of undamaged cells, when compared with both empty vector control cells and parental cells, but had drastic consequences for cells treated with nano-SiO2. The PARP-1 overtransfected cells were sensitized to the cytotoxic effects and DNA damage of nano-SiO2 compared with control parental cells. Meanwhile, flow cytometric analysis of nano-SiO2 stimulated poly(ADP-ribose) synthesis revealed consistently larger fractions of cells positive for this polymer in the PARP-1 overexpression cells than in control clones. Combining our previous research on PARP-1 knockdown HaCaT cells, we hypothesize that an optimal level of cellular poly(ADP-ribose) accumulation exists for the cellular recovery from DNA damage.

Occupational medicamentosa-like dermatitis induced by trichloroethylene (OMLDT) is a hypersensitivity disease with autoimmune liver injury, which has increasingly become a serious occupational health problem in China. However, the pathogenesis of OMLDT remained undefined. In this study, 30 TCE-induced OMLDT patients, 58 exposure controls, and 40 non-exposure controls were recruited. We showed that the ratio of activated CD4+ T cells (downregulation of CD62 L) was dramatically increased in OMLDT patients compared to exposure and non-exposure control, suggesting that CD4+ T cells activation was a key cellular event in the development of OMLDT. In parallel, the expression of cytokine including IL-2, IFN-γ, TNF-α and IL-17A were increased obviously and IL-4 decreased in CD4+ T cells from OMLDT patients. in vitro assay, we found that trichloroethylene metabolites trichloroacetaldehyde (TCAH), not trichloroacetic acid (TCA) or Trichloroethanol (TCOH) could activate the naïve CD4+ T cells characterized by a rise in intracellular calcium, down-regulated CD62 L and subsequently trigger the secretion of IL-2, IFN-γ and TNF-α. Notably, the phosphorylation status of NF-κB and p38MAPK were elevated in OMLDT patients. Moreover, TCAH also could activate the p38MAPK and NF-κB, suggesting the role of p38MAPK and NF-κB pathways in the activation of CD4+ T cells. In addition, we found that the inhibition of Schiff base formation decreased the ability of TCAH to induce the activation of naïve CD4+ T cells and p38MAPK and NF-κB pathway. In conclusion, we revealed that the CD4+ T activation and increased the cytokines including IL-2, IFN-γ and TNF-α but decreased IL-4 in CD4+ T cells were associated with OMLDT. TCAH could activate naïve CD4+ T cells through NF-κB and p38MAPK activation induced by Schiff base formation, which might contribute to the development of OMLDT. These findings provide a new insight into the pathogenesis of OMLDT.

Early diagnosis and treatment of occupational medicamentosa-like dermatitis due to trichloroethylene (OMLDT) are absence of specific and reliable diagnostic/therapeutic biomarkers. This study was conducted on 30 cases of OMLDT, 58 workers exposed to trichloroethylene (TCE) and 40 unexposed controls in order to identify any cytokine signatures that give an index to CD4(+) T cell differential and serve as biomarkers of OMLDT. Expression profiles of Th-1, Th-2, Th-17 and Treg cell type-specifying transcription factors and cytokines were analyzed using real time quantitative PCR (RT-qPCR) assay. To explore whether such expression profiles reflected their steady state plasma levels, a Luminex liquid fluorescence analysis was conducted. We found that the expression of transcription factors FoxP3 transcription factors (P = 0.006 and P < 0.0001) and IL-10 cytokine (P = 0.0008 and P < 0.0001) of the Treg subset were significantly higher in patients than TCE exposure workers and unexposed controls, suggesting that Treg cells were active after the occurrence of OMLDT. The transcript levels of IL-6 were significantly lower in the TCE exposure groups including patients and exposure workers as compared to the unexposed controls (P < 0.0001 and P = 0.0008). Circulating levels of assessed cytokines of IL-6 (P = 0.001 and P = 0.011) and TFN-alpha (P = 0.005 and P < 0.0001) were lower in the exposure groups than in the unexposed controls. Compared to the controls, the levels of IL-10 in patients were higher (P = 0.001 and P = 0.0008). There was a significantly positive correlation between the plasma levels IL-6 and IL-10 in TCE exposed workers. These alterations in the expression of transcription factors and cytokines highlight the underlying dysregulation of T cell subsets in OMLDT that reflect an immune tolerance or immune inhibition. Therefore, the elevation of IL-10 level may be a kind of pathogenesis indicator, and the decline in IL-6 level may be a kind of TCE exposure biomarker. These biomarkers need additional longitudinal follow-up studies to warrant to clinically useful biomarkers of OMLDT.

目的 探讨纳米二氧化硅(nano-SiO2)对人支气管上皮细胞(16HBE细胞)存活率和超氧化物歧化酶1(Superoxide Dismutase 1,SOD1)表达的影响.方法 以质量浓度为0～100 mg/L nano-SiO2处理16HBE细胞24 h,以CCK-8法检测细胞存活率,筛选合适的后续实验处理剂量.将16HBE细胞分为6组:溶剂对照组(予等体积溶剂处理)、微米SiO2对照组(予质量浓度为20 mg/L微米SiO2处理),5、10和20 mg/L nano-SiO2组(予相应终质量浓度的nano-SiO2处理),姜黄素组(先予终浓度为10 μmol/L的姜黄素处理2h,再予终质量浓度为20 mg/L的nano-SiO2处理).各组细胞经处理后,分别于培养4、12和24 h时间点收获细胞.采用荧光实时定量聚合酶链式反应检测细胞中SOD1 mRNA的相对表达水平,以蛋白免疫印迹法检测SOD1蛋白的相对表达水平.结果 随着nano-SiO2处理剂量的增加,细胞存活率下降,呈剂量-效应关系,有统计学意义(P＜0.01).在12和24 h时间点,nano-SiO2刺激后,16HBE细胞的SOD1的mRNA和蛋白相对表达水平均出现剂量依赖性下降(P＜0.01);与同时间点溶剂对照组比较,10和20 mg/L nano-SiO2组16HBE细胞的在上述2个时间点的SOD1 mRNA和蛋白相对表达水平均下降,差异有统计学意义(P＜0.05).在4、12和24 h时间点,20 mg/L nano-SiO2组16HBE细胞的SOD1 mRNA和蛋白相对表达水平均低于同时间点的微米SiO2对照组(P＜0.05),姜黄素组16HBE细胞的上述2个指标均高于20 mg/L nano-SiO2组(P＜0.05).结论 nano-SiO2刺激可导致16HBE细胞存活率下降并呈剂量依赖性;SOD1表达的下调可能是nano-SiO2致16HBE增殖抑制的机制之一.姜黄素对nano-SiO2诱导16HBE细胞损伤具有一定的保护作用.

目的 探讨纳米二氧化硅(SiO2)对人支气管上皮细胞(16HBE细胞)存活率和聚二磷酸腺苷核糖聚合酶-1(PARP-1)表达的影响.方法 ①以质量浓度为0～100 mg/L纳米SiO2处理16HBE细胞24.0 h,以CCK-8法检测细胞存活率.②将16HBE细胞分为6组:溶剂对照组(予等体积溶剂处理)、微米SiO2对照组(予终质量浓度为20 mg/L微米SiO2处理),5、10、20 mg/L纳米SiO2组(予相应终质量浓度的纳米SiO2处理),姜黄素组(先予终浓度为10μmol/L的姜黄素处理2.0 h,再予终质量浓度为20 mg/L的纳米SiO2处理).各组细胞经处理后,分别于培养4.0、12.0和24.0 h时间点收获细胞.采用荧光实时定量聚合酶链式反应检测细胞中PARP-1 mRNA的相对表达水平,以免疫印迹法检测PARP-1蛋白的相对表达水平.结果 ①随着纳米SiO2处理剂量的增加,细胞存活率下降,呈剂量-效应关系(P<0.01).②在12.0和24.0 h时间点,纳米SiO2刺激后,16HBE细胞的PARP-1 mRNA和蛋白相对表达水平均出现剂量依赖性下降(P<0.01);与同时间点溶剂对照组比较,5、10、20 mg/L纳米SiO2组16HBE细胞在该2个时间点的PARP-1 mRNA和蛋白相对表达水平均下降(P<0.05).在12.0和24.0 h时间点,20 mg/L纳米SiO2组16HBE细胞的PARP-1 mRNA和蛋白相对表达水平均低于同时间点的微米SiO2对照组(P<0.05);姜黄素组16HBE细胞的12.0 h时间点上述2个指标均高于20 mg/L纳米SiO2组(P<0.05).结论 纳米SiO2刺激可导致16HBE细胞存活率下降并呈剂量依赖性;PARP-1表达的下调可能是纳米SiO2致16HBE增殖抑制的机制之一.姜黄素对纳米SiO2诱导的16HBE的细胞损伤具有一定的保护作用.

OBJECTIVE: To explore effects of PM2.5 exposure on expression of oxidative stress and DNA methylation genes during zebrafish embryo development. METHODS:Samples of PM2.5 were collected by large-volume samplers on fiber filters. Then,the particle materials were collected by ultrasonicing and freeze-drying. Zebrafish embryos were exposed to PM2.5 particle materials in the concentrations of 0,5 and 20 μg/mL. After extraction of total RNA, relative expression of oxidative stress genes (sod1 and ogg1) and DNA methylation genes (tet1 and dnmt1) was detected by qPCR. RESULTS:2-6 h after PM2.5 exposure,expression of sod1,tet1 and dnmt1 were increased significantly with a dose-dependent relationship (r=0.98,0.98,0.99,P<0.05,respectively);2-6 h after PM2.5 exposure,expression of ogg1 was increased significantly in the 5 μg/mL group (P<0.05);24-48 h after PM2.5 exposure,expression of sod1, ogg1,tet1 and dnmt1 were decreased significantly compared with those in early stage (2-6 h). CONCLUSION:Expression of oxidative stress genes (sod1 and ogg1) and DNA methylation genes (tet1 and dnmt1) could be affected from exposure to PM2.5,especially during early embryo development.

Epidemiologic study has suggested that arsenic exposure is positively related to increased blood pressure. However, the underlying mechanism concerning interaction between genetic polymorphisms and arsenic exposure remains unclear. In present study, within 395 Chinese, the effects of interaction between arsenic exposure and CCM3 gene polymorphisms on elevation of blood pressure were probed by multiple Logistic regression models after adjusting for confounding factors. Firstly, we found that serum arsenic was positively associated with blood pressure, cholesterol, glucose and C-reactive protein. Then, adjusted for confounding factors of age, gender, smoking, alcohol consumption, BMI and degree of education, arsenic exposure incurred the hazard of increased systolic pressure and diastolic pressure, with odds ratios (ORs) being 1.725 and 1.425, respectively. Distinctly, we found that interactions between rs3804610* rs9818496, rs6784267*rs9818496, and rs3804610* rs6784267 variant genotype can increase significantly risks of SBP. Additionally, interactions between rs9818496, rs3804610 and rs6784267 genotypic variantions and arsenic exposure boosted the hazard of increased systolic pressure, with ORs being 1.496, 1.496 and 1.312. In conclusion, our fingdings suggest that As exposure of population can assist CCM3 polymorphism in elevating SBP.

Nano-SiO2 materials play a significant role in the engineered nanomaterials (ENMs) field. The ease of their production as well as their relatively low cost has promoted the wide use of these products in many fields. Nano-SiO2 exposure is known to cause severe DNA damage; however, the underlying mechanisms remain poorly understood. In a previous study, we found that nano-SiO2 exposure regulate the expression of the poly(ADP-ribose) polymerases-1 (PARP-1), a pivotal DNA repair gene, in human HaCaT cells. Here, we employed lentivirus-mediated RNA interference (RNAi) to knock down PAPR-1 expression in HaCaT cells and explored the potential role of PARP-1 in nano-SiO2 induced cytotoxicity. We found that nano-SiO2 treatment of HaCaT cells causes decreased cell viability, increased apoptosis and DNA damage. Nano-SiO2-treated HaCaT cells were also found to have slightly changed cell cycle distribution. Lentivirus-mediated PAPR-1 knockdown partially aggravated cytotoxicity and increased apoptosis induced by nano-SiO2 treatment. Nano-SiO2 had significant toxicity to human HaCaT cells and causes DNA damage. PAPR-1 knock-down cell line appears more sensitive to nano-SiO2 than the control cells in DNA damage. The results suggest that PAPR-1 is involved in protecting cells from damage caused by nano-SiO2.

We evaluated DNA damage levels of different categories of workers exposed to hazards inside electronics factories in Southern China. To find out the most dangerous risk factor, a cross-sectional study was conducted on a total of 584 exposed subjects and 138 controls in an electronics factory in Southern China, where the electronics industry is prevalent. The exposed hazards included isopropanol (IPO), lead, noise, video display terminals (VDT), lead in a high-temperature (high-temp) environment, and IPO in a high-temp environment. DNA damage detection was performed by the micro-whole blood comet assay using peripheral blood. DNA damage levels were estimated by percent tail DNA (%T). Linear regression models were used to test DNA damage differences between exposed groups and control group with adjustments for potential confounding factors. The level of DNA damage was more significant in both lead in a high-temp and IPO in a high-temp environment groups than in that of the controls (p<0.05). The differences remained significant after stratifying by smoking status (p<0.05). There were no significant differences between groups exposed to IPO, lead, noise, VDT environment and controls. In conclusion, we identified potential risk factors for DNA damage to electronics workers. Special attention should be paid to workers exposed to IPO and lead in a high-temp environment.

Alzheimer's disease (AD) is a devastating neurodegenerative disease accompanied by neuropsychiatric symptoms, such as anxiety and depression. The levels of melatonin decrease in brains of AD patients. The potential effect of melatonin on anxiety and depression behaviors in AD and the underlying mechanisms remain unclear. In this study, we treated 10-month-old triple transgenic mice of AD (3xTg-AD) with melatonin (10 mg/kg body weight/day) for 1 month and explored the effects of melatonin on anxiety and depression-like behaviors in 3xTg-AD mice and the protein expression of hippocampal tissues. The behavioral test showed that melatonin ameliorated anxiety and depression-like behaviors of 3xTg-AD mice as measured by open field test, elevated plus maze test, forced swimming test, and tail suspension test. By carrying out two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) coupled with mass spectrometry, we revealed a total of 46 differentially expressed proteins in hippocampus between the wild-type (WT) mice and non-treated 3xTg-AD mice. A total of 21 differentially expressed proteins were revealed in hippocampus between melatonin-treated and non-treated 3xTg-AD mice. Among these differentially expressed proteins, glutathione S-transferase P 1 (GSTP1) (an anxiety-associated protein) and complexin-1 (CPLX1) (a depression-associated protein) were significantly down-regulated in hippocampus of 3xTg-AD mice compared with the WT mice. The expression of these two proteins was modulated by melatonin treatment. Our study suggested that melatonin could be used as a potential candidate drug to improve the neuropsychiatric behaviors in AD via modulating the expression of the proteins (i.e. GSTP1 and CPLX1) involved in anxiety and depression behaviors. © 2017 BioFactors, 43(4):593-611, 2017.

Benzo(a)pyrene (BaP) is a ubiquitously distributed environmental pollutant and known carcinogen, which can induce malignant transformation in rodent and human cells. Poly(ADP-ribose) glycohydrolase (PARG), the primary enzyme that catalyzes the degradation of poly(ADP-ribose) (PAR), has been known to play an important role in regulating DNA damage repair and maintaining genomic stability. Although PARG has been shown to be a downstream effector of BaP, the role of PARG in BaP induced carcinogenesis remains unclear. In this study, we used the PARG-deficient human bronchial epithelial cell line (shPARG) as a model to examine how PARG contributed to the carcinogenesis induced by chronic BaP exposure under various concentrations (0, 10, 20 and 40 μM). Our results showed that PARG silencing dramatically reduced DNA damages, chromosome abnormalities, and micronuclei formations in the PARG-deficient human bronchial epithelial cells compared to the control cells (16HBE cells). Meanwhile, the wound healing assay showed that PARG silencing significantly inhibited BaP-induced cell migration. Furthermore, silencing of PARG significantly reduced the volume and weight of tumors in Balb/c nude mice injected with BaP induced transformed human bronchial epithelial cells. This was the first study that reported evidences to support an oncogenic role of PARG in BaP induced carcinogenesis, which provided a new perspective for our understanding in BaP exposure induced cancer.

Inducible nitric oxide synthase (NOS2) and endothelial nitric oxide synthase (NOS3) gene play important roles in the susceptibility to type 2 diabetes mellitus (T2DM). The present study aims to detect the potential association of NOS2 and NOS3 gene polymorphisms with the susceptibility toT2DM and diabetic nephropathy (DN) in the Chinese Han population. Four hundred and ninety T2DM patients and 485 healthy controls were enrolled in this case-control study. The genotypes of NOS2 and NOS3 gene polymorphisms were analyzed by the polymerase chain reaction (PCR)-ligase detection reaction (LDR) method. Our data demonstrated that the NOS2 rs2779248 and NOS2 rs1137933 genetic polymorphisms were significantly associated with the increased susceptibility to T2DM in the heterozygote comparison, dominant model, and allele contrast; and NOS3 rs3918188 genetic polymorphism was significantly associated with the increased susceptibility to T2DM in the homozygote comparison and recessive model. The allele-C and genotype-TC of NOS2 rs2779248, allele-A and genotype-GA of NOS2 rs1137933 and genotype-AA of NOS3 rs3918188 genetic polymorphisms might be the risk factors for increasing the susceptibility to T2DM. And a significant haplotype effect of NOS2 rs10459953/C- rs1137933/G- rs2779248/T was found between T2DM cases and controls. Moreover, NOS3 rs1800783 polymorphism was significantly associated with the increased susceptibility to DN in the heterozygote comparison, recessive model and allele contrast. At last, a positive correlation of family history of diabetes with NOS3 rs11771443 polymorphism was found in DN. These preliminary findings indicate that the NOS2 rs2779248, NOS2 rs1137933, and NOS3 rs3918188 genetic polymorphisms are potentially related to the susceptibility to T2DM, and the rs1800783 polymorphism might be considered as genetic risk factors for diabetic nephropathy, and family history of diabetes was closely associated with rs11771443 polymorphism in DN, and the genetic variants might be used as molecular markers for evaluating the risk of T2DM and diabetic nephropathy. © 2016 IUBMB Life, 68(7):516-525, 2016.

Mitochondrial dysfunction is involved in neurotoxicity caused by exposure of various chemicals such as copper. However, the effects of long-term low-dose copper exposure on mitochondrial proteome remain unclear. In this study, we found the treatment of copper (0.13ppm copper sulfate in drinking water) for 12 months caused abnormal expression of a total of 13 mitochondrial proteins (7 up-regulated and 6 down-regulated) as revealed by two-dimensional electrophoresis coupled with mass spectrometry in mouse cortex. Protein functional analysis revealed that these differentially expressed proteins mainly included apoptosis-associated proteins, axon guidance-associated proteins, axonogenesis-associated proteins and mitochondrial respiratory chain complex. Among these differentially expressed mitochondrial proteins, GRP75 (75kDa glucose-regulated protein) and GRP78 (78kDa glucose-regulated protein) were found to be significantly down-regulated as confirmed by Western-blot analysis. The down-regulation of GRP75 was shown to promote apoptosis. The down-regulation of GRP78/BiP could up-regulate endoplasmic reticulum (ER) stress mediators and thus cause apoptosis. Our study suggested that these differentially expressed mitochondrial proteins such as GRP75 and GRP78 could be involved in neurotoxicity caused by long-term low-dose copper exposure and serve as potential molecular targets for the treatment of copper neurotoxicity.

Human exposure to drinking water contaminated with arsenic is a serious global health concern and it predisposes people to cardiovascular diseases, such as hypertension, atherosclerosis, and microvascular diseases. Although accumulating evidence supports a role for angiogenesis responses to arsenic in the pathogenesis of the cardiovascular disease, the detailed molecular mechanism is not well understood. We aimed to determine the role and mechanism of microRNA (miRNA) in arsenic-induced angiogenesis. In our present study, sodium arsenite (NaAsO2) inhibited angiogenesis by decreasing cells proliferation, migration and tube formation in HUVECs. After NaAsO2 treatment, we found the expression of microRNA-425-5p (miR-425-5p) was reduced in vitro and in vivo and over-expression of miR-425-5p reversed the NaAsO2-induced anti-angiogenesis through its direct target cerebral cavernous malformation 3 (CCM3). Furthermore, we showed that NaAsO2 up-regulated CCM3 expression in vitro and in vivo. In addition, we demonstrated that inhibition of Notch and activation of VEGF/p38 signaling were involved in miR-425-5p blocking NaAsO2-induced anti-angiogenesis.

Recent studies suggest that copper exposure, even at very low levels, can produce significant toxic effects on the brains of mice. This study is aimed to explore the effects of low levels of copper on the hippocampal proteome of mice. Two-dimensional fluorescence difference gel electrophoresis was performed on hippocampal homogenate obtained from mice, which were given either drinking water only (control) or water supplemented with 0.13 ppm copper (copper-treated) for a period of 8 months beginning at an age of 3 months. A total of 9 differentially expressed proteins between copper-treated mice and control mice were identified. Protein functional analysis revealed that the altered proteins mainly involved energy metabolism-related proteins, synaptic proteins, molecular chaperones and cellular structural components. Among these differentially expressed proteins, serine racemase (SRR) and glial fibrillary acidic protein (GFAP) were significantly down-regulated and up-regulated, respectively, in the hippocampus of copper-treated mice compared with the control mice. SRR was shown to be involved in memory formation. The increased expression of GFAP, an astrocyte marker, indicated that long-term low levels of copper exposure caused activation of the inflammatory response, a process linked to spatial memory impairment. In agreement with the data from proteomic analysis, memory impairment was observed in copper-treated mice as measured by the Morris water maze test. In summary, this study has identified a number of abnormally expressed proteins in the hippocampus of copper-treated mice, and the identified protein, such as SRR, together with inflammatory responses, as evidenced by the increased expression of GFAP, could contribute to memory impairment resulting from copper exposure. Our findings provide insights for a better understanding of copper neurotoxicity at the protein level in response to low levels of copper exposure.