Identification the key factor of pulmonary fibrosis following silica nanoparticles exposure based on bioinformatics analysis / 中华劳动卫生职业病杂志

Objective: To investigate the main mechanisms of pulmonary fibrosis following silica nanoparticles (SiNPs) exposure through constructing the macrophage-fibroblast model in vitro, which simulated the process of pulmonary fibrosis. Methods: In January 2021, human mononuclear leukemia cells (THP-1) were treated with 0, 25, 50, 100 μg/ml SiNPs for 24 h. The supernatant of THP-1 cells was collected and applied to human embryonic lung fibroblast cells (MRC-5) which divided into control and low, medium and high dose groups at the logarithmic growth stage for 24 h. MRC-5 cell viability was detected by CCK8. The hydroxyproline (Hyp), interleukin 6 (IL-6), interleukin 1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) expression were detected in the supernatants of MRC-5. The changed proteins were detected by liquid-phase mass spectrometry in high dose group. GeneCard database were applied to identity the differential pulmonary fibrosis proteins in high dose group. Gene Ontology (GO) was performed to identity the key biological process in differential pulmonary fibrosis proteins of high dose group. The String database was used to construct the protein-protein interactions (PPI) network of differential pulmonary fibrosis proteins. The APP of CytoHubba was applied to calculate the key protein of differential pulmonary fibrosis proteins in PPI network. Correlation coefficients between key differential pulmonary fibrosis proteins were calculated using Pearson correlation analysis. Western blotting was applied to detect the expression of key proteins of differential pulmonary fibrosis proteins in different groups. Results: CCK8 results showed that MRC-5 cell viability was increasing in low, medium and high dose groups compared with control group (P<0.05). The expression levels of Hyp and IL-1β in different group were increased compared with control group, the expression levels of IL-6 and TNF-α were increased in high dose group compared with control group (P<0.05). GeneCard database identified 26 differential pulmonary fibrosis proteins, which were mainly involved in extracellular matrix hydrolysis, cell inflammatory response, tissue repair, cell proliferation, inflammation response by GO analysis. The APP of CytoHubba was calculated that matrix metalloproteinase 9 (MMP9) and tissue inhibitor metalloproteinase 1 (TIMP1) played an important role in PPI network. The results of correlation analysis showed that MMP9 was correlated with the expression of matrix metalloproteinase 1 (MMP1), matrix metalloproteinase 3 (MMP3), TIMP1 and epidermal growth factor receptor (EGFR) (r=0.97, 0.98, 0.94, 0.93, P<0.05). Western blotting results showed that TIMP1 protein expression was increased in low, medium and high dose groups, while MMP9 protein expression was increased only in high dose group (P<0.05) . Conclusion: Differential expression proteins related with pulmonary fibrosis in MRC-5 cells mainly regulate biological processes of extracellular matrix hydrolysis, tissue repair, and cellular inflammation response following SiNPs exposure. MMP9 and TIMP1 may be the key proteins, which affected the fibrosis process in vitro pulmonary fibrosis model.

The role of Nrf2 in the alteration of tight junction protein expression in choroid plexus epithelial cells created by lanthanum-activated MMP9 / 中华劳动卫生职业病杂志

Objective: To investigate the effect of nuclear factor erythroid 2-related factor 2 (Nrf2) in the alteration of tight junction protein expression in choroid plexus epithelial cells created by lanthanum-activated matrix metalloproteinase 9 (MMP9) . Methods: In October 2020, immortalized rat choroid plexus epithelial cell line (Z310) cells were used as the blood-cerebrospinal fluid barrier in vitro, and were divided into control group and 0.125, 0.25, 0.5 mmol/L lanthanum chloride (LaCl(3)) treatment group. After treating Z310 cells with different concentrations of LaCl(3) for 24 hours, the morphological changes of Z310 cells were observed under inverted microscope, the protein expression levels of MMP9, occludin and zonula occludens-1 (ZO-1) were observed by cellular immunofluorescence method, and the protein expression levels of MMP9, tissue inhibitors of metalloproteinase1 (TIMP1) , occludin, ZO-1 and Nrf2 were detected by Western blotting. The level of reactive oxygen species (ROS) in cells was detected by flow cytometry. Results: Compared with the control group, Z310 cells in the LaCl(3) treatment group were smaller in size, with fewer intercellular junctions, and more dead cells and cell fragments. The expression level of MMP9 protein in cells treated with 0.25 and 0.5 mmol/L LaCl(3) was significantly higher than that in the control group (P<0.05) , and the expression level of TIMP1 and tight junction proteins occudin and ZO-1 was significantly lower than that in the control group (P<0.05) . Compared with the control group, the ROS production level in the 0.25, 0.5 mmol/L LaCl(3) treatment group was significantly increased (P<0.05) , and the Nrf2 protein expression level in the 0.125, 0.25, 0.5 mmol/L LaCl(3) treatment group was significantly decreased (P<0.05) . Conclusion: Lanthanum may increase the level of ROS in cells by down regulating the expression of Nrf2, thus activating MMP9 to reduce the expression level of intercellular tight junction proteins occludin and ZO-1.

The relationship between copper-related protein and neurobehavioral function in individuals with occupational exposure to low-level lead / 中国职业医学

OBJECTIVE: To analyze the relationship between the neurobehavioral functions of individuals exposed to low-level lead and the levels of serum copper-related proteins glutathione S-transferase M1(GSTM1), hypoxia inducible factor-1 alpha(HIF1α), cyclooxygenase 1(COX1) and metallothionein(MT), and to screen biomarkers for changes in neurobehavioral function caused by occupational lead exposure. METHODS: A total of 194 workers who exposed to low-level lead(lead-exposed group) and 120 workers without lead exposure(control group) were selected from a battery factory as the research subjects by judgment sampling method. The inductively coupled plasma-mass spectrometry was used to determine blood lead levels of the two groups, and the State of Mood Scale(POMS) was investigated to assess the emotional state. The computerized neurobehavioral evaluation system in Chinese version 3(NES-C3) was used to test the neurobehavioral ability index(NAI) of related indicators of learning memory and mental activity. Enzyme-linked immunosorbent assay was used to detect the levels of copper-related protein in serum. After using principal component analysis to extract the principal components of emotional state, learning memory and mental activity, multiple linear regression was used to analyze the influencing factors of neurobehavioral function. RESULTS: The blood lead level of the lead-exposed group was increased [(57.15±11.12) vs(177.86±80.04) μg/L, P<0.01], and the incidence of symptoms such as dizziness, memory loss, sleep disturbance, fatigue, weakness, cold sweats in extremities, cold extremities, tingling of extremities, tingling sensation in the distal extremities, tetany, instability of holding things, metallic taste in the mouth, nausea and vomiting, anorexia, constipation, abdominal distension, abdominal pain, toothache/tooth loosening were increased(all P<0.01) compared with the control group. Meanwhile, the scores of tension-anxiety, depression-dejection, fatigue-inertia, anger-hostility, confusion-bewilderment of POMS were increased(all P<0.01), and the scores of vigor-activity were decreased(P<0.01). The NAI of the lead-exposed individuals in the NES-C3 test of 6 indicators(series addition and subtraction, visual retention, memory scanning, listening to digital breadth, visual simple reaction time, target tracking) were lower than that of the control group(all P<0.01). The serum levels of GSTM1 and HIF1α of the lead-exposed group decreased(all P<0.01), and the COX1 and MT levels increased(all P<0.01) compared with the control group. The serum GSTM1, HIF1α, COX1 and MT of the lead-exposed group were correlated with their emotional state, learning and memory and mental activity to varying degrees(all P<0.05). The results of multiple stepwise linear regression showed that serum COX1 level was an independent influencing factor of emotional state(P<0.01), serum GSTM1, COX1 and lead working years were independent influencing factor of learning and memory(all P<0.05), and work length with lead exposure and alcohol consumption was an independent influencing factor of mental activity(all P<0.05). CONCLUSION: Low-level lead exposure can cause central nervous system symptoms in workers, and the change in neurobehavioral function and serum levels of copper-related proteins GSTM1, HIF1α, COX1 and MT. Serum levels of GSTM1 and COX1 can be used as candidate biomarkers for indicating neurobehavioral function caused by lead exposure.

Role of copper transporter protein in copper accumulation in C6 cells induced by lead exposure / 中国职业医学

OBJECTIVE: To investigate the role of copper transporter protein and copper chaperones in copper accumulation in glioma cell line C6 cells induced by lead acetate exposure. METHODS: i) CCK-8 assay was used to determine the proper lead acetate dose by treating the cells with lead acetate at the final concentration of 0-50 μmol / L for 24. 0 hours. ii) C6 cells were divided into control group and lead-exposure group,treated with 0 and 10 μmol / L lead acetate respectively for24. 0 hours,and then cultured in 2 μmol / L copper chloride for 0. 0,0. 5,1. 0,2. 0,4. 0 and 8. 0 hours; inductively coupled plasma mass spectrometry was used to detect the levels of copper and lead in the cells. Real-time polymerase chain reaction was used to detect the mRNA expression of copper transporter 1( CTR1),divalent metal transporter 1( DMT1),copper-transporting ATPase α polypeptide / β polypeptide( ATP7 A and ATP7B), antioxidant 1 copper chaperone( ATOX1),cytochrome c oxidase copper chaperone( COX17),and copper-chaperone-for-superoxide dismutase( CCS).Laser con-focal microscopy was applied to detect the protein expression of CTR1 and ATP7 A in cells. RESULTS: i) CCK-8assay proved that the 10 μmol / L lead acetate treatment did not affect C6 cells proliferation( P > 0. 05). Thus the final concentration of 10 μmol / L lead acetate was chosen as the treatment dose in later experiments. ii) After 10 μmol / L lead acetate exposure for 24. 0 hours,the lead and copper levels of C6 cells in lead-exposure group were higher than those in the control group( P < 0. 01),but there was no statistical significant difference in the C6 cell survival rate between these two groups( P > 0. 05). After cells were treated with copper,the C6 cell survival rate of lead-exposure group was lower than that in the control group( P < 0. 01). The interactive effect of copper level showed statistical significance between lead exposure and cooper treatment time( P < 0. 01). At the 5 time points from 0. 5-8. 0 hours after exposure to copper,the copper levels in lead-exposure group were higher than those of control group( P < 0. 05). The copper levels in the control group reached a peak after exposure to copper for 2. 0 hours,and maintained at a stable level till the time point of 8. 0hours. The copper levels of lead-exposed groups increased with the increasing time of copper exposure and there was a time-effect relationship,and they reached to the peak at the time point of 8. 0 hours. After 10 μmol / L lead acetate exposure for 24. 0 hours,compared with control group,the CTR1 and DMT1 mRNA relative expression levels in leadexposed group increased by 113. 00% and 36. 00% respectively( P < 0. 01),and the ATP7 A mRNA relative expression level decreased by 25. 00%( P < 0. 01). The protein expression of CTR1 increased by 76. 04%( P < 0. 01),and the protein expression of ATP7 A decreased by 16. 0%( P < 0. 01). There was no significant difference in the mRNA relative expression levels of ATP7 B,ATOX1,COX17 and CCS between the two groups( P > 0. 05). CONCLUSION: Lead acetate exposure can lead to increase accumulation of copper in C6 cells with increasing exposure time showing a time-effect relationship. The increased protein expression of CTR1 and decreased protein expression of ATP7 A might be one of the mechanisms of inducing copper accumulation in cells after the lead acetate exposure.

Disorder of copper homeostasis induced by lead exposure among mice and intervention effect of quercetin / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the effect of lead exposure on copper and copper metalloenzyme and the intervention effect of quercetin.</p><p><b>METHODS</b>Twenty-four specific pathogen-free male Sprague-Dawley rats of good health were randomly divided into control group (n = 8), lead acetate group (n = 8), and lead acetate + quercetin group (n = 8). The rats in lead acetate group were poisoned by drinking water with 1 g/L lead acetate for 8 weeks, while the rats in control group were fed by drinking water with sodium acetate of the same volume for 8 weeks; the rats in lead acetate+quercetin group were intraperitoneally injected with quercetin (30 mg × kg-1 × d-1) for 8 weeks while drinking water with lead acetate. The Morris water maze was used to test the learning and memory abilities of rats. The lead and copper levels in the serum, hippocampus, cortex, and bone were measured by graphite furnace atomic absorption spectrometry. The level of advanced glycation end products, activity of Cu/Zn superoxide dismutase (SOD), and content and activity of ceruloplasmin (CP) in the hippocampus and serum were measured using a test kit. HE staining was performed to observe the pathological changes in the hippocampus.</p><p><b>RESULTS</b>The Morris water maze test showed that the latency in lead acetate group (52.50±12.04 s) was significantly longer than that in control group (28.08±7.31 s) (P<0.05), and the number of platform crossings was significantly lower in the lead acetate group than in the control group. Compared with those in the control group, the lead levels in the cortex and hippocampus in lead acetate group increased 2.72-fold and 3.79-fold, and the copper in the cortex and hippocampus, and serum free copper levels in lead acetate group increased 1.15-fold, 1.48-fold, and 6.44-fold. Compared with the control group, the lead acetate group had a lower content of CP in the hippocampus (1.23±0.40 U/mg provs0.78±0.08 U/mg pro) and 31.81%and 19.49%decreases in CP content and Cu/Zn SOD activity. Free copper level in serum was positively correlated with the latency and lead levels in the serum, cortex, and hippocampus. The escape latency of rats in lead acetate + quercetin group was decreased by 42.15% (P<0.05). The lead levels in the cortex and hippocampus in lead acetate + quercetin group (0.246 ± 0.58 µg/g and 0.202±0.049 µg/g) were significantly lower than those in lead acetate group (0.391±0.49 µg/g and 0.546±0.120 µg/g), but the free copper and copper levels in the hippocampus and cortex were not significantly reduced. The lead acetate + quercetin group had higher Cu/Zn SOD activity and CP content in the hippocampus than the lead acetate group (P < 0.05). The light microscope observation showed that the number of cells in the hippocampus was reduced with disordered arrangement in the lead acetate group; with quercetin intervention, the hippocampus damage was reduced.</p><p><b>CONCLUSION</b>Lead exposure results in disorder of copper homeostasis, while quercetin may alleviate the damage induced by lead to some extent.</p>

Effects of acrylamide on the permeability of blood cerebrospinal fluid barrier in rats / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To explore the effects of acrylamide on the permeability of blood cerebrospinal fluid barrier (BCB) and tight junction protein ZO-1 of choroid plexus in rats and to provide a theoretical basis for explaining the mechanism of nerve injury induced by acrylamide.</p><p><b>METHODS</b>Thirty two male Sprague-Dawley rats were randomly divided into ACR and control groups. ACR group was exposed to 20 mg/kg ACR daily for 5 days a week by intraperitoneal injection (i.p.) for 4 weeks. Control group was exposed to normal saline. The neurobehavioral tests (including sensatory and motor functions) were performed every week. At the end of exposure, Evan blue (EB) and Sodium fluorescein (NaFI) content in rat CSF were detected for determining the BCB permeability, Real-time PCR was used to measure the expression levels of ZO-1 mRNA in the epithelium cells of choroid plexus, and laser scanning confocal microscope (LSCM) was utilized to observe the distribution of ZO-1 protein.</p><p><b>RESULTS</b>Neurobehavioral tests showed that the tail-flick latencies of ACR group were 27.77% and 53.71% as long as control group in the 3rd week and 4th week, respectively (P < 0.05). The hind lamb splay distances of ACR group were 131.76% and 153.77% as long as control group in the 3rd week and 4th week, respectively (P < 0.05). Evan blue (EB) and Sodium fluorescein (NaFI) content of ACR group were significantly higher than those of control group (P < 0.05). In the 4th week, the expression level of ZO-1 mRNA in ACR group was 0.21 +/- 0.07, which was significantly lower than that (0.31 +/- 0.11) in control group (P < 0.05). In the 4th week, the ZO-1 protein expression level of choroid plexus in ACR group was significantly lower than that in control group (P < 0.05).</p><p><b>CONCLUSION</b>Acrylamide could increased the BCB permeability of rats, which may be involved in the central nervous injury induced by ACR.</p>

The change of pulmonary surfactant protein of rat following silica exposure / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the change of lung surfactant protein (SP) A,B,C,D of rats following silica dust exposure in order to provide the evidences for the early diagnosis indices or therapy of silicosis.</p><p><b>METHODS</b>60 male SD rats were randomly divided into silica group, and corresponding controls group. Rats in silica group were administrated 1 ml silica solution by intratracheal instillation at dose of 50 mg/ml. Rats in control group were administrated the same amount saline. At 3rd, 7th, 14th, 21st, 28th after silica exposure, serum and bronchoalveolar lavage fluid (BALF) samples were obtained. The concentration of SP-A, SP-B, SP-C, SP-D in serum and BALF were measured by using enzyme immunoassay (ELISA). Meanwhile the levels of total anti-oxidative activity (T-AOC) and hydroxyproline (HYP) in lung tissue were also detected. The pathology of lung tissue was conducted.</p><p><b>RESULTS</b>Compared with control group, SP-A concentration in BALF of silica exposed rat for 3, 14, 21, 28d was significant lower and SP-D concentration in BALF of silica exposed rat for all time points was also lower. The differences were significant (P < 0.05). Meanwhile SP-B level in 7, 14, 21, 28 d silica exposed rats BALF and SP-C level in 14, 21, 28 d silica exposed rats markedly decreased (P < 0.05). In addition compared with control group, SP-A, SP-B and SP-C concentration in serum of silica exposed rat were higher when SP-A for 14, 21, 28 d silica exposure, SP-B for 7, 14, 21 d silica exposure and Sp-C for 7, 14, 21, 28 d exposure. And all difference were significant (P < 0.05). As silica exposure time increased, SP-C concentration in serum showed an increase trend, which showed a time-response relationship (r = 0.618, P = 0.042). However, SP-D concentration in serum of rat for 7, 14, 21, 28d silica exposure were significant lower than that of control group (P < 0.005). And there was a decrease trend with time point exposure regarding of SP-D (r = -0.731, P = 0.016). The HYP content in lung tissue of experiment rats increased at 3rd, 7th, 14th, 21st and 28th day time point and The T-AOC activity in lung tissue decrease at, 7th, 14th, 21st and 28th day time point. The differences were significant (P < 0.05). There was a positive correlation (P = 0.803, P = 0.045) between SP-C in BALF and HYP of silica exposed rats and a negative correlation between SP-D in BALF and HYP (r = -0.867, P = 0.033). No significant correlation were seen between SP-A, SP-B BALF and HYP (y = 0.416, P = 0.28; r = 0.592, P = 0.071). SP-C concentration in BALF and serum all showed an increased trend and a positive correlation was seen (r = 0.539, P = 0.046). The same decrease trend was seen between SP-D in BALF and serum and correlation value was 0.870 (P = 0.034).</p><p><b>CONCLUSION</b>The silica exposure did cause the change of SP content both in BALF and serum. The SP-C and SP-D content in serum might be served as an early effective biomarker of silicosis.</p>

The effect of 2,5-hexanedione on nerve growth factor in sciatic nerve of rats and VSC4.1 cell / 中华预防医学杂志

<p><b>OBJECTIVE</b>To explore the effect of 2,5-hexanedione (2,5-HD) on the levels of nerve growth factor (NGF) in sciatic nerve of rats and motor-neurons.</p><p><b>METHOD</b>A total of 50 Wistar rats were randomly designed into five groups and intoxicated with 400 mgxkg(-1)xd(-1) 2,5-HD for 0, 7, 14, 21, 28 d. Immunohistochemistry and real-time PCR were used to detect the levels of NGF and NGF mRNA. Motor neuron VSC4.1 cells were administrated with 0, 2.5, 5.0, 10.0, 20.0 mmol/L 2,5-HD for 24 h and 10.0 mmol/L 2,5-HD was chosen to intoxicated VSC4.1 cells for 0, 1, 3, 6, 12, 24, 48 h respectively. Immunofluorescence technique was selected to detect the levels of NGF.</p><p><b>RESULTS</b>The NGF level in sciatic nerve of rats administrated with 400 mgxkg(-1)xd(-1) 2,5-HD showed increase tendency at begin and then decrease after exposure. The NGF mRNA level in 14 d (2(-DeltaDeltaCt)= 3.46), 21 d (2(-DeltaDeltaCt)= 5.28) and 28 d (2(-DeltaDeltaCt)= 3.10) were higher than those in 0 d (2(-DeltaDeltaCt)= 1) and 7 d (2(-DeltaDeltaCt)= 0.78). In vitro tests of VSC4.1 cells showed that NGF levels in 5.0 mmol/L (43.24 +/- 7.52), 10.0 mmol/L (43.48 +/- 10.86) and 20.0 mmol/L (63.13 +/- 10.68) were higher than those in 0 mmol/L (16.32 +/- 4.20)(q values were 19.92, 19.72, 32.78, respectively, P < 0.01) and 2.5 mmol/L (19.78 +/- 2.66) (q values were 17.50, 17.42, 30.63, respectively, P < 0.01) in 24 h and the NGF level in 20.0 mmol/L was higher than those in 5.0 mmol/L (q = 13.04, P < 0.01) and 10.0 mmol/L (q = 11.71, P < 0.01). The NGF levels of VSC4.1 cells with 10.0 mmol/L 2,5-HD in 6 h (18.66 +/- 2.89), 12 h (23.14 +/- 6.08), 24 h (27.66 +/- 6.11) and 48 h (17.25 +/- 3.05) were increased compared with that in 0 h (10.18 +/- 1.81) (q values were 9.64, 15.74, 21.76, 8.50, respectively, P < 0.01), 1 h (9.31 +/- 1.28) (q values were 10.28, 16.17, 21.95, 9.20, respectively, P < 0.01) and 3 h (10.44 +/- 2.13) (q values were 9.25, 15.24, 21.17, 8.10, respectively, P < 0.01), and NGF levels in 12 h and 24 h increased compared with those in 6 h (q values were 5.24, 10.77, respectively, P < 0.01) and 48 h (q values were 7.31, 13.26, respectively, P < 0.01).</p><p><b>CONCLUSION</b>2,5-HD could increase NGF levels in sciatic nerve of rats and motor-neurons, and the dose or time dependent effects were observed in this study.</p>

Preliminary study of biomarker in blood or cerebrospinal fluid of rat following manganese exposure / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To explore the biomarkers of manganese exposure by measuring the manganese (Mn) and iron (Fe) level as well as the mRNA change of Hepcidin, divalent metal-ion transporter-1 (DMT1) and Parkin-2, one of genes related to Parkinson disease in body fluid and brain tissues of rat.</p><p><b>METHODS</b>Male Sprague-Dawley rats were administered (i.p) either MnCl2 solution (6 mg Mn/kg) or the same volume saline, 5 times per week and for 4 weeks. Graphic furnace Atom Absorption Spectrum (AAS) was applied to measure the concentration of Mn and Fe in brain tissue and body fluids. Meanwhile Hepcidin, DMT1 and Parkin-2 mRNA expression were detected by real-time RT-PCR.</p><p><b>RESULTS</b>Mn concentration in erythrocytes of rats was the 86.9 folds of that in control; No significant change was found in plasma. However the trend and range of Mn increase in cerebrospinal fluid (CSF) was the same as that in brain tissue including striatum, cortex, hippocampus and choroid plexus. Meanwhile Fe concentration in brain tissue of Mn exposed rats was also higher than that of control, whose trend was as same as that in CSF. However iron concentration in plasma decreased. The real-time RT-PCR data also showed that Hepcidin mRNA expression in Mn-exposed rat decreased 56% in blood, which was in line with its expression in cortex(67%). Similarly, Parkin-2 mRNA expression decreased both in blood (42%) and in striatum. However DMT1 mRNA expression increase 38% in striatum of Mn-exposed rats but decreased in blood.</p><p><b>CONCLUSION</b>Hepcidin and Parkin-2 mRNA expression in blood might be serves as the effective biomarkers following manganese exposure, certainly which needs to be further explored.</p>

Effect of 2, 5-hexanedione on calcium homeostasis of motor neuron / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To explore the mechanism of cytotoxic effect of 2, 5-hexanedione (2, 5-HD) on motor neuron.</p><p><b>METHODS</b>Vsc4.1 (a cell line from motor neuron) was incubated with a series concentration of 2, 5-HD. The cell viability, Ca(2+) Mg(2+) ATPase and Na(+)K(+) ATPase were detected. Laser scanning confocal microscope (LSCM) was used for detecting intracellular calcium level. The average calcium level in VSC4.1 was measured by flow cytometry.</p><p><b>RESULTS</b>The cell viability was decreased when Vsc4.1 cells were treated with 2, 5-HD at the dosage of 2.5, 5.0, 7.5, 10, 15 and 20 mmol/L for 24 hours. Compared with the control group the activity of Ca(2+) Mg(2+) ATPase was decreased to 70.02%, 77.44% and 47.47% respectively; the activity of Na(+)K(+) ATPase was decreased to 82.07%, 72.45% and 50.71%. The difference was significant. Intracellular free calcium of VSC4.1 cell was increased rapidly within 10 s and then recovered within 40 seconds when it was exposed to 33.5 mmol/L 2, 5-HD. An increase in intracellular calcium was observed when the VSC4.1 was treated with 33.5 mmol/L 2, 5-HD. The peak of intracellular calcium level occurred ten minutes later.</p><p><b>CONCLUSION</b>The disturbance of calcium homeostasis may be involved in the mechanisms of neurotoxicity of 2, 5-HD.</p>