Activated astroglial cells are implicated in neuropathogenesis of many infectious and inflammatory diseases of the brain. A number of inflammatory mediators and cytokines have been proposed to play a key role in glial cell-related brain damage. Cytokine production seems to be initiated by signaling through TLR4/type I IL-1R (IL-1RI) in response to their ligands, LPS and IL-1β, playing vital roles in innate host defense against infections, inflammation, injury, and stress. We have shown that glial cells are stimulated by ethanol, up-regulating cytokines and inflammatory mediators associated with TLR4 and IL-1RI signaling pathways in brain, suggesting that ethanol may contribute to brain damage via inflammation. We explore the possibility that ethanol, in the absence of LPS or IL-1β, triggers signaling pathways and inflammatory mediators through TLR4 and/or IL-1RI activation in astrocytes. We show in this study that ethanol, at physiologically relevant concentrations, is capable of inducing rapid phosphorylation within 10 min of IL-1R-associated kinase, ERK1/2, stress-activated protein kinase/JNK, and p38 MAPK in astrocytes. Then an activation of NF-κB and AP-1 occurs after 30 min of ethanol treatment along with an up-regulation of inducible NO synthase and cyclooxygenase-2 expression. Finally, we note an increase in cell death after 3 h of treatment. Furthermore, by using either anti-TLR4- or anti-IL-1RI-neutralizing Abs, before and during ethanol treatment, we inhibit ethanol-induced signaling events, including NF-κB and AP-1 activation, inducible NO synthase, and cyclooxygenase-2 up-regulation and astrocyte death. In summary, these findings indicate that both TLR4 and IL-1RI activation occur upon ethanol treatment, and suggest that signaling through these receptors mediates ethanol-induced inflammatory events in astrocytes and brain.

Inflammatory processes and cytokine expression have been implicated in the pathogenesis of several neurodegenerative disorders. Chronic ethanol intake induces brain damage, although the mechanisms involved in this effect are not well understood. We tested the hypothesis that activation of glial cells by ethanol would induce stimulation of signaling pathways and inflammatory mediators in brain, and would cause neurotoxicity. We used cerebral cortex from control and chronic ethanol-fed rats, which received ethanol-liquid diet for 5 months and cultured of astrocytes exposed to 75 mM ethanol for 7 days. Our results demonstrate that chronic ethanol treatment up-regulates iNOS, COX-2 and IL-1beta in rat cerebral cortex and in cultured astrocytes. Under both experimental conditions, up-regulation of these inflammatory mediators and IL-1RI concomitantly occurs with the stimulation of IRAK and MAP kinases, including ERK1/2, p-38 and JNK, which trigger the downstream activation of oxidant-sensitive transcription factors NF-KB and AP-1. These effects were associated with an increased in both caspase-3 and apoptosis in ethanol-fed rats and in astrocytes exposed to ethanol. In conclusion, chronic ethanol treatment stimulates glial cells, up-regulating the production and the expression of inflammatory mediators in the brain, and activating signalling pathways and transcription factors involved in inflammatory damage and cell death.

The effect of chronic and in vitro ethanol exposure on brain oxygen radical formation and lipid peroxidation was analyzed . Ethanol induces a dose-dependent increase in lipid peroxidation in brain homogenates. The peroxidative effects of alcohol seem to be related to both cytochrome P450 and the ethanol-inducible form of cytochrome P450 (CYP2E1), because preincubation with metyrapone (an inhibitor of cytochrome P450) or with an antibody against CYP2E1 abolished the ethanol-increased lipid peroxidation . Using the formation of dichlorofluorescein, we also demonstrated that both in vitro and chronic alcohol exposure significantly enhanced the formation of oxygen radical species in synaptosomes . Chronic alcohol treatment also leads to an induction of cytochrome P450 (230%), NADPH cytochrome c reductase (180%), NADPH oxidation (184%), and CYP2E1 in brain microsomes. In addition, this treatment produced a decrease in the GSH/GSSG ratio in brain and significantly enhanced the levels of superoxide dismutase and catalase activities . This mechanism could be involved in the toxic effects of ethanol on brain and membrane alterations occurring after chronic ethanol intake . Key Words: Ethanol-Brain-Lipid peroxidation-Oxygen reactive species-Cytochrome P450 (CYP2E1) .

We demonstrate the presence of cytochrome P4502E1 (CYP2E1) in astrocytes in primary culture, its induction by ethanol, and the concomitant generation of free radical species. Double immunofluorescence using anti‐CYP2E1 and anti‐glial fibrillary acidic protein showed that CYP2E1 was distributed over the cytoplasm and processes, although labeling was more pronounced over the nuclear membrane. Immunogold labeling confirmed this pattern of distribution. Addition of 25 mM ethanol to the astrocyte culture medium for 14 days resulted in an increase in the CYP2E1 content, as determined by confocal microscopy and dot blot. In addition, ethanol induced a dose‐dependent increase in the formation of reactive oxygen species that was partially prevented by incubating the astrocytes with anti‐CYP2E1. Alcohol also induced a dose‐dependent increase in malonaldehyde and hydroxynonenal formation and a depletion of the glutathione (GSH) content. These results suggest that ethanol induces oxidative damage in astrocytes, which could explain some of the toxic effects of ethanol on these cells, such as cytoskeletal alterations. This assumption is supported here by the fact that an increase in GSH content prevents the deleterious effects of alcohol on the cytoskeleton of astrocytes. These results suggest that importance of oxidative stress as a mechanism involved in alcohol‐induced neural and brain damage.

Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron (MN) disease. Its primary cause remains elusive, although a combination of different causal factors cannot be ruled out. There is no cure, and prognosis is poor. Most patients with ALS die due to disease-related complications, such as respiratory failure, within three years of diagnosis. While the underlying mechanisms are unclear, different cell types (microglia, astrocytes, macrophages and T cell subsets) appear to play key roles in the pathophysiology of the disease. Neuroinflammation and oxidative stress pave the way leading to neurodegeneration and MN death. ALS-associated mitochondrial dysfunction occurs at different levels, and these organelles are involved in the mechanism of MN death. Molecular and cellular interactions are presented here as a sequential cascade of events. Based on our present knowledge, the discussion leads to the idea that feasible therapeutic strategies should focus in interfering with the pathophysiology of the disease at different steps.