Roles of aquaporins and matrix metalloproteinases in mouse brain edema formation induced by subacute exposure to 1,2-dichloroethane

Molecular mechanisms of 1,2-dichloroethane-induced neurotoxicity

The production of industrial solvents and adhesives often utilizes 1,2-dichloroethane (1,2-DCE), a highly toxic halogenated hydrocarbon compound. Occupational 1,2-DCE poisoning occurs frequently and is a public health concern. Exposure to 1,2-DCE can damage the brain, liver, and kidneys. The main and most severe damage caused by exposure to 1,2-DCE is to the nervous system, especially the central nervous system. Current research on 1,2-DCE mainly focuses on the mechanism of brain edema. Several possible mechanisms of 1,2-DCE neurotoxicity have been proposed, including oxidative stress, calcium overload, blood-brain barrier damage, and neurotransmitter changes. This article reviews the research progress on 1,2-DCE neurotoxicity and the mechanism behind it to provide a scientific basis for the prevention and treatment of 1,2-DCE poisoning.

Disturbance of glutamate metabolism and inhibition of CaM-CaMKII-CREB signaling pathway in the hippocampus of mice induced by 1,2-dichloroethane exposure

1,2-Dichloroethane (1,2-DCE) is a highly toxic neurotoxicity, and the brain tissue is the main target organ. At present, long-term exposure to 1,2-DCE has been shown to cause cognitive dysfunction in some studies, but the mechanism is not clear. The results of this study showed that long-term 1,2-DCE exposure decreased learning and memory abilities in mice and impaired the structure and morphology of neurons in the hippocampal region. Moreover, except for the mRNA level of PAG, the enzymatic activities and protein levels of GS and PAG, as well as the mRNA level of GS were inhibited. With increasing dose of exposure, the protein and mRNA expression of GLAST and GLT-1 also decreased. Contrarily, there were protein and mRNA expression upregulation of GluN1, GluN2A and GluN2B in the hippocampus, as well as increased levels of extracellular Glu and intracellular Ca²⁺. In addition, 1,2-DCE exposure also downregulated the protein expression levels of CaM, CaMKII and CREB. Taken together, our results suggest that long-term 1,2-DCE exposure impairs the learning and memory capacity in mice, which may be attributed to the disruption of Glu metabolism and the inhibition of CaM- CaMKII-CREB signaling pathway in the hippocampus.

Cerebral edema after ischemic stroke: Pathophysiology and underlying mechanisms

Ischemic stroke is associated with increasing morbidity and has become the main cause of death and disability worldwide. Cerebral edema is a serious complication arising from ischemic stroke. It causes an increase in intracranial pressure, rapid deterioration of neurological symptoms, and formation of cerebral hernia, and is an important risk factor for adverse outcomes after stroke. To date, the detailed mechanism of cerebral edema after stroke remains unclear. This limits advances in prevention and treatment strategies as well as drug development. This review discusses the classification and pathological characteristics of cerebral edema, the possible relationship of the development of cerebral edema after ischemic stroke with aquaporin 4, the SUR1-TRPM4 channel, matrix metalloproteinase 9, microRNA, cerebral venous reflux, inflammatory reactions, and cerebral ischemia/reperfusion injury. It also summarizes research on new therapeutic drugs for post-stroke cerebral edema. Thus, this review provides a reference for further studies and for clinical treatment of cerebral edema after ischemic stroke.

1,2-Dichloroethane induces cortex demyelination by depressing myelin basic protein via inhibiting aquaporin 4 in mice

1,2-Dichloroethane (1,2-DCE) is a pervasive environmental pollutant, and overexposure to this hazardous material causes brain edema and demyelination in humans. We found that 1,2-DCE inhibits aquaporin 4 (AQP4) and is a primary pathogenic effector of 1,2-DCE-induced brain edema in animals. However, AQP4 down-regulation's link with cortex demyelination after 1,2-DCE exposure remains unclear. Thus, we exposed wild-type (WT) CD-1 mice and AQP4 knockout (AQP4-KO) mice to 0, 100, 350 and 700 mg/m³ 1,2-DCE by inhalation for 28 days. We applied label-free proteomics and a cell co-culture system to elucidate the role of AQP4 inhibition in 1,2-DCE-induced demyelination. The results showed that 1,2-DCE down-regulated AQP4 in the WT mouse cortexes. Both 1,2-DCE exposure and AQP4 deletion induced neurotoxicity in mice, including increased brain water content, abnormal pathological vacuolations, and neurobehavioral damage. Tests for interaction of multiple regression analysis highlighted different effects of 1,2-DCE exposure level depending on the genotype, indicating the core role of AQP4 in regulation on 1,2-DCE-caused neurotoxicity. We used label-free quantitative proteomics to detect differentially expressed proteins associated with 1,2-DCE exposure and AQP4 inhibition, and identified down-regulation in myelin basic protein (MBP) and tyrosine-protein kinase Fyn (FYN) in a dose-dependent manner in WT mice but not in AQP4-KO mice. 1,2-DCE and AQP4 deletion separately resulted in demyelination, as detected by Luxol fast blue staining, and manifested as disordered nerve fibers and cavitation in the cortexes. Western blot and immunofluorescence confirmed the decreased AQP4 in the astrocytes and the down-regulated MBP in the oligodendrocytes by 1,2-DCE exposure and AQP4 inhibition, respectively. Finally, the co-culture results of SVG p12 and MO3.13 cells showed that 1,2-DCE-induced AQP4 down-regulation in the astrocytes was responsible for demyelination, by decreasing MBP in the oligodendrocytes. In conclusion, 1,2-DCE induced cortex demyelination by depressing MBP via AQP4 inhibition in the mice.

Roles of Crosstalk between Astrocytes and Microglia in Triggering Neuroinflammation and Brain Edema Formation in 1,2-Dichloroethane-Intoxicated Mice

We have previously reported that the activation of astrocytes and microglia may lead to the overproduction of proinflammatory mediators, which could induce neuroinflammation and cause brain edema in 1,2-dichloroethane (1,2-DCE)-intoxicated mice. In this research, we further hypothesized that astrocyte–microglia crosstalk might trigger neuroinflammation and contribute to brain edema in 1,2-DCE-intoxicated mice. The present research revealed, for the first time, that subacute intoxication with 1,2-DCE might provoke the proinflammatory polarization of microglia, and pretreatment with minocycline, a specific inhibitor of microglial activation, may attenuate the enhanced protein levels of ionized calcium-binding adapter molecule1 (Iba-1), cluster of differentiation 11b (CD11b), glial fibrillary acidic protein (GFAP), soluble calcium-binding protein 100B (S100B), tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), inducible nitric oxide synthase (iNOS), vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), matrix metalloproteinase-9 (MMP-9), Toll-like receptor 4 (TLR4), MyD88, and p-p65, and ameliorate the suppressed protein expression levels of occludin and claudin 5; we also observed changes in water content and made pathological observations on edema in the brains of 1,2-DCE-intoxicated mice. Moreover, pretreatment with fluorocitrate, an inhibitor of reactive astrocytes, could also reverse the alteration in protein expression levels of GFAP, S100B, Iba-1, CD11b, TNF-α, IL-6, iNOS, VCAM-1, ICAM-1, MMP-9, occludin, and claudin 5 in the brain of 1,2-DCE intoxicated mice. Furthermore, pretreatment with melatonin, a well-known anti-inflammatory drug, could also attenuate the above-mentioned changes in the brains of 1,2-DCE-intoxicated mice. Altogether, the findings from this research indicated that microglial activation might play an important role in triggering neuroinflammation, and hence may contribute to brain edema formation; additionally, the findings suggested that molecular crosstalk between reactive astrocytes and activated microglia may amplify the neuroinflammatory reaction, which could induce secondary brain injury in 1,2-DCE-intoxicated mice.

1,2-Dichloroethane induces cerebellum granular cell apoptosis via mitochondrial pathway in vitro and in vivo

1,2-Dichloroethane (1,2-DCE) is a widely used chlorinated organic toxicant, but little is known about the cerebellar dysfunction induced by excessive exposure to it. To uncover 1,2-DCE-induced neurotoxicity in cerebellar granular cells (CGCs), and to investigate the underlying mechanisms, we explored this, both in vitro and in vivo. Our findings showed significant cell viability inhibition in human CGCs (HCGCs) treated with 1,2-DCE. Flow cytometry and mitochondrial membrane potential analyses discovered an increase in apoptotic-mediated cell death in HCGCs after 1,2-DCE treatment. This HCGC apoptosis was involved in the increases of protein expression in Cytochrome c, Caspase-3, Bad, Bim, transformation related protein 53, Caspase-8, tumor necrosis factor-α, and Survivin. Quantitative real-time PCR (qPCR) and western blot confirmed the increases in Cytochrome c, Caspase-3, cleaved Caspase-3, and Bad in HCGCs after 1,2-DCE treatment. Bax inhibitor peptide V5 rescued 1,2-DCE-induced HCGC apoptosis. Furthermore, 80 CD-1 male mice were exposed to 1,2-DCE by inhalation at 0, 100, 350, and 700 mg/m³ for 6 h/day for 4 weeks. An open field test found abnormal neurobehavioral changes in the mice exposed to 1,2-DCE. Histopathological examination showed significantly shrunken and hypereosinophilic cytoplasm with nuclear pyknosis in mouse CGCs from the 700 mg/m³ 1,2-DCE group. TdT-mediated dUTP nick-end labeling assay verified significant increases in apoptotic positive cells in the mouse CGCs after 1,2-DCE exposure. We confirmed the increases in the expressions of Cytochrome c, Caspase-3, cleaved Caspase-3 and Bad in the mice exposed to 1,2-DCE. These findings suggest that 1,2-DCE exposure can induce CGC apoptosis and cerebellar dysfunction, at least in part, through mitochondrial pathway.

Upregulation of CYP2E1 expression causes oxidative damage induced by 2-chloroethanol in primary cultured rat astrocytes

Brain edema caused by subacute poisoning with 1,2-dichloroethane (1,2-DCE) has gained much attention during recent years, but its underlying mechanism is poorly understood. As an intermediate metabolite of 1,2-DCE in vivo, 2-chloroethanol (2-CE) can be transformed into chloroacetaldehyde and reactive oxygen species (ROS) through cytochrome P450 2E1 (CYP2E1) mediated metabolism. In previous studies, it was found that CYP2E1 expression is enhanced in the brain of mice treated with 1,2-DCE. This study was designed to verify the roles of CYP2E1 overexpression in 2-CE induced cytotoxicity in rat astrocytes, and the contribution of specific signaling molecules to the upregulation of CYP2E1 expression caused by 2-CE. The results of this study demonstrate that treatment with 2-CE can enhance CYP2E1 protein and mRNA levels, cause an increase in ROS and MDA levels, and higher percentages of apoptotic cells in rat astrocytes. Pretreatment with either diallyl sulfide or vitamin C, the inhibitor of CYP2E1 or scavenger of ROS, respectively, can suppress the levels of CYP2E1 expression, ROS and MDA, ameliorate cell apoptosis, and attenuate phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) in these cells. Additionally, pretreatment with the inhibitor of either ERK1/2 or transcriptional factor specificity protein 1 (SP1) can suppress the CYP2E1 expression, and alleviate the oxidative damage caused to these cells. In conclusion, our findings demonstrate that CYP2E1 overexpression plays a crucial role in 2-CE induced oxidative damage of rat astrocytes, and that CYP2E1 expression is upregulated partially through the activation of the ERK1/2 and SP1 signaling pathways by ROS generated during CYP2E1-mediated 2-CE metabolism. This study provides novel information that can be used in elucidating the mechanism by which 1,2-DCE induces brain edema.

Neuroinflammatory Reactions in the Brain of 1,2-DCE-Intoxicated Mice during Brain Edema

We previously reported that expression of matrix metalloproteinase-9 (MMP-9) mRNA and protein was upregulated during 1,2-dichloroethane (1,2-DCE) induced brain edema in mice. We also found that the p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway resulted in MMP-9 overexpression and nuclear factor-κB (NF-κB) activation in mice treated with 1,2-DCE. In this study, we further hypothesized that inflammatory reactions mediated by the p38 MAPK/ NF-κB signaling pathway might be involved in MMP-9 overexpression, blood–brain barrier (BBB) disruption and edema formation in the brain of 1,2-DCE-intoxicated mice. Our results revealed that subacute poisoning by 1,2-DCE upregulates protein levels of glial fibrillary acidic protein (GFAP), ionized calcium-binding adapter molecule 1 (Iba-1), interleukin-1β (IL-1β), vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), inducible nitric oxide synthase (iNOS) and p-p65 in mouse brains. Pretreatment with an inhibitor against p38 MAPK attenuates these changes. Moreover, pretreatment with an inhibitor against NF-κB attenuates alterations in brain water content, pathological indications notable in brain edema, as well as mRNA and protein expression on levels of MMP-9, VCAM-1, ICAM-1, iNOS, and IL-1β, tight junction proteins (TJs), GFAP and Iba-1 in the brain of 1,2-DCE-intoxicated mice. Furthermore, pretreatment with an inhibitor against MMP-9 obstructs the decrease of TJs in the brain of 1,2-DCE-intoxicated mice. Lastly, pretreatment with an antagonist against the IL-1β receptor also attenuates changes in protein levels of p-p38 MAPK, p-p65, p-IκB, VCAM -1, ICAM-1, IL-1β, and Iba-1 in the brain of 1,2-DCE-intoxicated-mice. Taken together, findings from the current study indicate that the p38 MAPK/ NF-κB signaling pathway might be involved in the activation of glial cells, and the overproduction of proinflammatory factors, which might induce inflammatory reactions in the brain of 1,2-DCE-intoxicated mice that leads to brain edema.

Toxic effects of combined treatment of 1,2-dichloroethane and ethanol on mouse brain and the related mechanisms

The aim of this study was to explore the mechanisms of brain damage induced by the combined treatment of mice with 1,2-dichloroethane (1,2-DCE) and ethanol. Mice were divided into control group; 1,2-DCE-intoxicated group; ethanol-treated group; and low-, medium-, and high-dose combined treatment groups. Histological observations along with brain organ coefficients and water content were used to measure the brain damage directly and indirectly. The levels of nonprotein sulfhydryls, malondialdehyde (MDA), and superoxide dismutase activity were used as parameters to evaluate oxidative stress in the brain. Protein and messenger RNA (mRNA) levels of cytochrome P450 2E1 (CYP2E1), zonula occludens-1 (occludin and zo-1), aquaporin-4 (AQP4), nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase (HO)-1, and the γ-glutamyl cysteine synthetase catalytic and modulatory subunits (γ-GCSc, GR, and γ-GCSm) in the brain were examined by Western blot analysis and quantitative polymerase chain reaction analysis, respectively. Effects of the combined treatment of 1,2-DCE and ethanol were evaluated by analysis of variance with a factorial design. The results suggested that combined exposure to ethanol and 1,2-DCE synergistically increased CYP2E1 protein and mRNA levels, accelerated the metabolism of ethanol and 1,2-DCE in the brain tissue, induced high production of reactive oxygen species (ROS), and increased MDA levels, thereby damaging the blood-brain barrier and causing obvious pathological changes in brain tissue. However, the increased level of ROS activated the Nrf2 signal transduction pathway, promoting the expression of HO-1 and glutathione-related antioxidant enzymes in the brain to protect the cells from oxidative damage.

Involvement of CYP2E1 in the Course of Brain Edema Induced by Subacute Poisoning With 1,2-Dichloroethane in Mice

This study was designed to explore the role of cytochrome P4502E1 (CYP2E1) expression in the course of brain edema induced by subacute poisoning with 1,2-dichloroethane (1,2-DCE). Mice were randomly divided into five groups: the control group, the 1,2-DCE poisoned group, and the low-, medium- and high-dose diallyl sulfide (DAS) intervention groups. The present study found that CYP2E1 expression levels in the brains of the 1,2-DCE-poisoned group were upregulated transcriptionally; in contrast, the levels were suppressed by DAS pretreatment in the intervention groups. In addition, the expression levels of both Nrf2 and HO-1 were also upregulated transcriptionally in the brains of the 1,2-DCE-poisoned group, while they were suppressed dose-dependently in the intervention groups. Moreover, compared with the control group, MDA levels and water contents in the brains of the 1,2-DCE-poisoned group increased, whereas NPSH levels and tight junction (TJ) protein levels decreased significantly. Conversely, compared with the 1,2-DCE- poisoned group, MDA levels and water contents in the brains of the intervention groups decreased, and NPSH levels and TJ protein levels increased significantly. Furthermore, pathological changes of brain edema observed in the 1,2-DCE-poisoned group were markedly improved in the intervention groups. Collectively, our results suggested that CYP2E1 expression could be transcriptionally upregulated in 1,2-DCE-poisoned mice, which might enhance 1,2-DCE metabolism in vivo, and induce oxidative damage and TJ disruption in the brain, ultimately leading to brain edema.

1,2-Dichloroethane-induced hepatotoxicity and apoptosis by inhibition of ERK 1/2 pathways

1,2-Dichloroethane (DCE) is a ubiquitous occupational environmental contaminant. Subacute exposure to DCE can cause severe toxic encephalopathy and has obvious toxic effects on the liver. However, the toxicity of DCE on the liver and its molecular mechanism remain elusive. In the present study, we established a DCE-exposed animal model by inhalation in SD rats and used HepG2 cells in in vitro tests. The DCE-exposed groups showed hepatic dysfunction relative to the control group. Moreover, apoptotic cells and decreased phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) were found in liver tissue of rats in 3 DCE-exposed groups. In vitro tests showed that short-term exposure to DCE induced apoptosis in HepG2 cells. Furthermore, the incubation of cells with DCE significantly decreased the phosphorylation of ERK1/2 in a concentration-dependent manner. Additionally, incubating HepG2 cells with epidermal growth factor, an ERK1/2 activator, significantly increased apoptosis in HepG2 cells. In conclusion, our results suggest that DCE induces apoptosis in HepG2 cells by inhibiting ERK1/2 pathways.

Association of NF-κB and AP-1 with MMP-9 Overexpression in 2-Chloroethanol Exposed Rat Astrocytes

Subacute poisoning of 1,2-dichloroethane (1,2-DCE) has become a serious occupational problem in China, and brain edema is its main pathological consequence, but little is known about the underlying mechanisms. As the metabolite of 1,2-DCE, 2-chloroethanol (2-CE) is more reactive, and might play an important role in the toxic effects of 1,2-DCE. In our previous studies, we found that matrix metalloproteinases-9 (MMP-9) expression was enhanced in mouse brains upon treatment with 1,2-DCE, and in rat astrocytes exposed to 2-CE. In the present study, we analyzed the association of nuclear factor kappa B (NF-κB) and activator protein-1 (AP-1) with MMP-9 overexpression in astrocytes treated with 2-CE. MMP-9, p65, c-Jun, and c-Fos were significantly upregulated by 2-CE treatment, which also enhanced phosphorylation of c-Jun, c-Fos and inhibitor of κBα (IκBα), and nuclear translocation of p65. Furthermore, inhibition of IκBα phosphorylation and AP-1 activity with the specific inhibitors could attenuate MMP-9 overexpression in the cells. On the other hand, inhibition of p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway suppressed the activation of both NF-κB and AP-1 in 2-CE-treated astrocytes. In conclusion, MMP-9 overexpression induced by 2-CE in astrocytes could be mediated at least in part through the p38 signaling pathway via activation of both NF-κB and AP-1. This study might provide novel clues for clarifying the mechanisms underlying 1,2-DCE associated cerebral edema.

Involvement of the p38 MAPK signaling pathway in overexpression of matrix metalloproteinase-9 during the course of brain edema in 1,2-dichloroethane-intoxicated mice

Accumulated data have revealed that subacute poisoning of 1,2-dichloroethane (1,2-DCE), an industrial solvent used in some countries can cause encephalopathy, in which brain edema is the main pathological change. However, the underlying mechanisms are unclear. In the present study, we hypothesized that the p38 MAPK (p38) signaling pathway could be activated in 1,2-DCE-intoxicated mice, which in turn stimulates transcription factors, such as nuclear factor-κB (NF-κB) and activator protein-1 (AP-1), and then enhances the expression of proinflammatory factors, including matrix metalloproteinase-9 (MMP-9), finally leading to blood-brain barrier (BBB) disruption and brain edema formation. Our results revealed that brain water content and BBB permeability increased significantly in the intoxicated mice. Meanwhile, the levels of phosphorylated p38 (p-p38) and inhibitory κBα (p-IκB), as well as the expression levels of MMP-9, c-jun, c-fos, and p65, also increased markedly in the brains of intoxicated mice. Conversely, the protein levels of ZO-1, occludin and claudin-5 in these mice decreased markedly, but their JAM-1 protein levels increased dramatically. Our results revealed that p-p38 levels in the brains of intoxicated mice were suppressed by pretreatment with a p38 inhibitor. In response to suppressed p-p38 levels, the brain water contents and DNA binding activities of NF-κB and AP-1, as well as the expression levels of MMP-9, c-jun, c-fos, p65, p-IκB and JAM-1, decreased, whereas the protein levels of ZO-1, occludin and claudin-5 increased markedly. Taken together, our findings indicated that the p38 signaling pathway might be activated and involved in the course of brain edema in 1,2-DCE-intoxicated mice.

Effects of developmental arsenite exposure on hippocampal synapses in mouse offspring

arsenite. The thickness of the postsynaptic density (PSD) decreased, whereas the width of the synaptic cleft widened significantly in arsenite exposure groups. Moreover, protein expression of both PSD-95 and SYP decreased significantly in arsenite exposure groups. In conclusion, the results of this study demonstrated that developmental arsenite exposure could depress the expression of synaptic proteins, subsequently cause alteration in synaptic structures, and finally contribute to arsenite-induced deficits in spatial learning and memory ability in mouse offspring.

Disruption of Intracellular ATP Generation and Tight Junction Protein Expression during the Course of Brain Edema Induced by Subacute Poisoning of 1,2-Dichloroethane

The aim of this study was to explore changes in intracellular ATP generation and tight junction protein expression during the course of brain edema induced by subacute poisoning of 1,2-dichloroethane (1,2-DCE). Mice were exposed to 1.2 g/m³ 1,2-DCE for 3.5 h per day for 1, 2, or 3 days, namely group A, B, and C. Na⁺-K⁺-ATPase and Ca²⁺-ATPase activity, ATP and lactic acid content, intracellular free Ca²⁺ concentration and ZO-1 and occludin expression in the brain were measured. Results of present study disclosed that Ca²⁺-ATPase activities in group B and C, and Na⁺/K⁺-ATPase activity in group C decreased, whereas intracellular free Ca²⁺ concentrations in group B and C increased significantly compared with control. Moreover, ATP content decreased, whereas lactic acid content increased significantly in group C compared with control. On the other hand, expressions of ZO-1 and occludin at both the protein and gene levels in group B and C decreased significantly compared with control. In conclusion, findings from this study suggest that calcium overload and depressed expression of tight junction associated proteins, such as ZO-1 and occludin might play an important role in the early phase of brain edema formation induced by subacute poisoning of 1,2-DCE.

1,2-Dichloroethane Induces Reproductive Toxicity Mediated by the CREM/CREB Signaling Pathway in Male NIH Swiss Mice

1,2-Dichloroethane (1,2-DCE) is a widely used chlorinated organic toxicant but little is known about the reproductive disorders induced by its excessive exposure. To reveal 1,2-DCE-induced male reproductive toxicity and to elucidate the underlying mechanisms, we exposed male National Institutes of Health Swiss mice to 1,2-DCE by inhalation at 0, 100, 350, and 700 mg/m3 for 6 h/day, for 1 and 4 weeks. Our findings showed a significant decrease in body weight with increased testis/body weight ratio, reduced sperm concentration and induced malformation of spermatozoa, and vacuolar degeneration of germ cells in the seminiferous tubules of testes in mice exposed to 1,2-DCE. Cyclic adenosine monophosphate (cAMP)-response element binding protein (CREB) and cAMP-response element modulator (CREM) were significantly inhibited by 1,2-DCE. This is consistent with the declines in the transducer of regulated CREB activity 1 and activator of CREM in testis, which results in the decrease in lactate dehydrogenase C and testis-specific kinase 1 in the testes. Moreover, the activation of p53 and Bax with the inhibition of Bcl-2 might be the reason for the upregulation of caspase-3 in the apoptosis, as detected by TdT-mediated dUTP nick-end labeling assay in the testes induced by 1,2-DCE. Finally, elevated testosterone levels were found along with increased levels of gonadotropin-releasing hormone, cAMP, luteinizing hormone (LH), and LH receptors in the testes. These findings suggest that 1,2-DCE inhibits CREM/CREB signaling cascade and subsequently induces apoptosis associated with p53 activation and mitochondrial dysfunction. This also results in induced malformation of spermatozoa, reduced sperm concentration, and pathological impairment of the testes.

Upregulation of Matrix Metalloproteinase-9 in Primary Cultured Rat Astrocytes Induced by 2-Chloroethanol Via MAPK Signal Pathways

2-Chloroethanol (2-CE) is one of the reactive metabolites of 1,2-DCE in vivo, which might contribute to brain edema formation induced by 1,2-dichloroethane (1,2-DCE) poisoning. Thus, the purpose of this study was to explore the roles of mitogen-activated protein kinase (MAPK) signal pathways in upregulation of matrix metalloproteinase-9 (MMP-9) in 2-CE exposed rat astrocytes. Expression of p38 MAPK (p38), extracellular signal regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK) and MMP-9 at both protein and gene levels in rat astrocytes were determined using western blot and real-time RT-PCR methods. The results showed that both protein and mRNA levels of MMP-9 in 2-CE exposed astrocytes significantly increased. Meanwhile, protein levels of phosphorylated p38 (p-p38), ERK1/2 (p-ERK1/2) and JNK1/2 (p-JNK1/2) in 2-CE exposed astrocytes also significantly increased. In addition, both protein and mRNA levels of MMP-9 significantly decreased in response to reduced protein levels of p-p38, p-ERK1/2 and p-JNK1/2 achieved by supplement with their specific inhibitors, indicating that activation of MAPK signal pathways might play an important role in upregulation of MMP-9 expression at the transcriptional level in 2-CE exposed astrocytes. Furthermore, since pretreatment of n-acetyl-l-cysteine (NAC), a powerful antioxidant amino acid, could attenuate the elevated levels of MMP-9, p-p38, p-ERK2 and p-JNK1/2 in 2-CE exposed astrocytes, activation of MAPK signal pathways in 2-CE exposed astrocytes could be mediated partially by reactive oxygen species (ROS), which was most likely generated in the metabolism of 2-CE.

2-Chloroethanol Induced Upregulation of Matrix Metalloproteinase-2 in Primary Cultured Rat Astrocytes Via MAPK Signal Pathways

This study was to explore the mechanisms underlying 1,2-dichloroethane (1,2-DCE) induced brain edema by focusing on alteration of matrix metalloproteinase-2 (MMP-2) in rat astrocytes induced by 2-chloroethanol (2-CE), an intermediate metabolite of 1,2-DCE in vivo. Protein and mRNA levels of MMP-2, and the phosphorylated protein levels of p38 MAPK (p-p38), extracellular signal regulated protein kinase (p-ERK1/2) and c-Jun N-terminal kinase (p-JNK1/2) in astrocytes were examined by immunostaining, western blot or real-time RT-PCR analysis. Findings from this study disclosed that protein levels of MMP-2 were upregulated by 2-CE in astrocytes. Meanwhile, protein levels of p-p38, p-ERK1/2 and p-JNK1/2 were also increased apparently in the cells treated with 2-CE. Moreover, pretreatment of astrocytes with SB202190 (inhibitor of p38 MAPK), U0126 (inhibitor of ERK1/2) or SP600125 (inhibitor of JNK1/2) could suppress the upregulated expression of p-p38, p-ERK1/2, and p-JNK1/2. In response to suppressed protein levels of p-p38 and p-JNK1/2, the protein levels of MMP-2 also decreased significantly, indicating that activation of MAPK signal pathways were involved in the mechanisms underlying 2-CE-induced upregulation of MMP-2 expression.

Immunohistochemical localization of aquaporin 4 (AQP4) in the porcine gastrointestinal tract

The water channel aquaporin-4 (AQP4) is a protein widely expressed on plasma membrane of a variety of epithelial cells. In this study we investigated the expression of AQP4 in the gastrointestinal tract of the pig using immunohistochemical staining. We found no presence of AQP4 in the different regions of the pig stomach. In the porcine small intestine moderate immunoreactivity to AQP4 was detected in enterocytes (along the villi and in the bottom of the crypts), duodenal Brunner’s glands and in enteric ganglia in cells lying in close vicinity to myenteric as well as submucous neurons. In superficial epithelial cells of the colonic mucosa as well as of caecal and colonic glands a very strong immunoreactivity to AQP4 was found. Both in the myenteric and submucous ganglia of the large intestine AQP4-positive cells surrounding enteric neurons were observed. We concluded that AQP4 expression in the porcine gastrointestinal tract showed some species-dependent differences in relation to other species. Based on the presented distribution pattern of AQP4, it is likely that the aquaporin plays a role in mucous (but not acid) secretion and intestinal absorptive processes in the pig.

1,2-Dichloroethane induced nephrotoxicity through ROS mediated apoptosis in vitro and in vivo

1,2-Dichloroethane (DCE) decreased kidney cell proliferation, even induced cell apoptosisviaincreasing the generation of ROS in the presence of an extra-metabolic system.