PubMed · 9097101
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
1995. Crotonaldehyde.. https://pubmed.ncbi.nlm.nih.gov/9097101/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Abnormalities in oxidative metabolism and inflammation accompany many neurodegenerative diseases. Thiamine deficiency (TD) is an animal model in which chronic oxidative stress and inflammation lead to selective neuronal death, whereas other cell types show an inflammatory response. Therefore, the current studies determined the response of different brain cell types to TD and/or inflammation in vitro and tested whether their responses reflect inherent properties of the cells. The cells that have been implicated in TD-induced neurotoxicity, including neurons, microglia, astrocytes, and brain endothelial cells, as well as neuroblastoma and BV-2 microglial cell lines, were cultured in either thiamine-depleted media or in normal culture media with amprolium, a thiamine transport inhibitor. The activity levels of a key mitochondrial enzyme, alpha-ketoglutarate dehydrogenase complex (KGDHC), were uniquely distributed among different cell types: The highest activity was in the endothelial cells, and the lowest was in primary microglia and neurons. The unique distribution of the activity did not account for the selective response to TD. TD slightly inhibited general cellular dehydrogenases in all cell types, whereas it significantly reduced the activity of KGDHC exclusively in primary neurons and neuroblastoma cells. Among the cell types tested, only in neurons did TD induce apoptosis and cause the accumulation of 4-hydroxy-2-nonenal, a lipid peroxidation product. On the other hand, chronic lipopolysaccharide-induced inflammation significantly inhibited cellular dehydrogenase and KGDHC activities in microglia and astrocytes but not in neurons or endothelial cells. The results demonstrate that the selective cell changes during TD in vivo reflect inherent properties of the different brain cell types.
The transcription factor activator protein-1 (AP-1) is activated in response to physiological activity in neuronal circuits and in response to neuronal injury associated with various acute and chronic neurodegenerative conditions. The membrane lipid peroxidation product 4-hydroxy-2,3-nonenal (HNE) is increasingly implicated in the disruption of neuronal calcium homeostasis that occurs in various paradigms of neuronal excitotoxicity and apoptosis. The possible mechanistic links between lipid peroxidation and alterations in gene transcription during neuronal apoptosis have not previously been examined. We now report that exposure of cultured rat cortical neurons to an apoptotic concentration of HNE results in a large increase in AP-1 DNA-binding activity. The protein synthesis inhibitor cycloheximide blocked the induction of AP-1, consistent with a requirement for induction of expression of AP-1 family members. The broad-spectrum caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone and the caspase-3 inhibitor N-acetyl-Asp-Glu-Val-Asp-aldehyde blocked HNE-induced increases in AP-1 DNA-binding activity, demonstrating a requirement for caspase activation in the activation of AP-1. HNE induced phosphorylation of c-Jun N-terminal kinase (JNK), which was prevented by caspase inhibitors, indicating that HNE was acting at or upstream of JNK phosphorylation. The intracellular calcium chelator BAPTA-acetoxymethyl ester completely prevented stimulation of AP-1 DNA-binding by HNE, indicating a requirement for calcium. Moreover, agents that suppress mitochondrial calcium uptake (ruthenium red) and membrane permeability transition (cyclosporin A) attenuated AP-1 activation by HNE, suggesting a contribution of mitochondrial alterations to AP-1 activation. Collectively, our data suggest a scenario in which HNE disrupts neuronal calcium homeostasis and perturbs mitochondrial function, resulting in caspase activation. Activated caspases, in turn, induce activation of JNK, resulting in stimulation of AP-1 DNA-binding protein production. This transcriptional pathway induced by HNE may modulate the cell death process.
To explore the pathogenesis in placental dysfunction and abruptio placentae, we analyzed the occurrence of placental cell apoptosis and the role of Fas and Fas ligand (L) in that process in an inflammatory placental dysfunction model of pregnant mice, using lipopolysaccharides (LPS). In the present study, Day 13 pregnant mice were injected i.p. with LPS (50 microg/kg) or saline as a control, and the placentas were isolated at various time points after the injection. Analysis of the isolated DNA in agarose-gel electrophoresis revealed a typical ladder pattern of bands consisting of 180-200 base pairs (bp), which is regarded as a hallmark of apoptosis. The intensity of the bands increased time-dependently, reaching a maximum level at 12 h after LPS injection. In accord with the biochemical data, histochemical analysis using terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) revealed that nuclei positive for double-stranded DNA breaks were found in decidua, diploid trophoblasts in the basal zone, and spongiotrophoblasts. The number of positive nuclei was maximized at 12 h after LPS injection. As a next step, we investigated the possible involvement of Fas and Fas L in the induction of apoptosis of the placental cells after LPS injection. Western blot analysis indicated that LPS increased the expression of Fas and Fas L in the placenta by about 4-fold at 12 h and 18 h, respectively, after injection. The cells expressing Fas and Fas L were identified, using immunohistochemistry and nonradioactive in situ hybridization, as decidua, diploid trophoblasts in the basal zone, and spongiotrophoblasts. Furthermore, when the expression of 4-hydroxy-2-nonenal (HNE)-modified proteins was assessed to evaluate the relation of oxidative stress elicited by LPS to the induction of apoptosis, once again decidua, diploid trophoblasts in the basal zone, and spongiotrophoblasts were positive. Therefore, the placental dysfunction by LPS may be brought about by the Fas-mediated apoptosis of various placental cells in a paracrine/autocrine fashion, possibly under the influence of oxidative stress.