Aspirin Protects Dopaminergic Neurons Against Lipopolysaccharide-Induced Neurotoxicity in Primary Midbrain Cultures

Protective effect of aspirin and gentisic acid, a plant-derived phenolic acid, on acrylamide-induced neurotoxicity by inhibiting apoptosis and autophagy

Acrylamide (ACR) is a toxic agent for humans and animals. Gentisic acid, an aspirin metabolite, has antioxidant activity. Therefore, the present study investigated the probable protective effects of aspirin and gentisic acid on ACR-induced neurotoxicity in PC12 cells and rats. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was used to assess the effects of aspirin and gentisic acid (1.25, 2.5, 5 µM) on ACR (5 mM) toxicity. Male Wistar rats were randomly divided into 13 groups: (1) Control group, (2) ACR (50 mg/kg, 11 days, i.p.), (3-5) ACR + aspirin (25, 50, 75 mg/kg, 11 days, p.o.), (6-8) ACR + gentisic acid (25, 50, 75 mg/kg, 11 days, p.o.), (9) ACR + vitamin E (200 mg/kg, every other day, i.p.), (10, 11) Aspirin (75, 100 mg/kg, 11 days, p.o.), (12, 13) Gentisic acid (75, 100 mg/kg, 11 days, p.o.). Behavioral tests were assessed on the final day of the study. In the cerebral cortex, malondialdehyde (MDA), glutathione (GSH), cleaved-caspase-3, and microtubule-associated protein 1A/1B-light chain 3 (LC3) protein levels were evaluated. When compared with the ACR group, aspirin (2.5, 5 µM) and gentisic acid (2.5 µM) significantly enhanced cell viability. In comparison to the control group, ACR induced severe motor impairment, elevated MDA, cleaved-caspase-3, LC3 II/I ratio, and decreased GSH levels in the cerebral cortex of rats. ACR-induced changes were significantly reversed by aspirin and gentisic acid (25 mg/kg). Oxidative stress, apoptosis, and autophagy play important roles in the neurotoxicity of ACR. Aspirin and gentisic acid significantly reduced ACR-induced toxicity by inhibiting the mentioned mechanisms.

Antioxidant Properties of Oral Antithrombotic Therapies in Atherosclerotic Disease and Atrial Fibrillation

The thrombosis-related diseases are one of the leading causes of illness and death in the general population, and despite significant improvements in long-term survival due to remarkable advances in pharmacologic therapy, they continue to pose a tremendous burden on healthcare systems. The oxidative stress plays a role of pivotal importance in thrombosis pathophysiology. The anticoagulant and antiplatelet drugs commonly used in the management of thrombosis-related diseases show several pleiotropic effects, beyond the antithrombotic effects. The present review aims to describe the current evidence about the antioxidant effects of the oral antithrombotic therapies in patients with atherosclerotic disease and atrial fibrillation.

Action of low doses of Aspirin in Inflammation and Oxidative Stress induced by aβ1-42 on Astrocytes in primary culture

Aspirin has been used as anti-inflammatory and anti-aggregate for decades but the precise mechanism(s) of action after the presence of the toxic peptide Aβ_1-42 in cultured astrocytes remains poorly resolved. Here we use low-doses of aspirin (10^-7 M) in astrocytes in primary culture in presence or absence of Aβ_1-42 toxic peptide. We noted an increase of cell viability and proliferation with or without Aβ_1-42 peptide presence in aspirin treated cells. In addition, a decrease in apoptosis, determined by Caspase 3 activity and the expression of Cyt c and Smac/Diablo, were detected. Also, aspirin diminished necrosis process (LDH levels), pro-inflammatory mediators (IL-β and TNF-α) and NF-ᴋB protein expression, increasing anti-inflammatory PPAR-γ protein expression, preventing Aβ_1-42 toxic effects. Aspirin inhibited COX-2 and iNOS without changes in COX-1 expression, increasing anti-oxidant protein (Cu/Zn-SOD and Mn-SOD) expression in presence or absence of Aβ_1-42. Taken together, our results show that aspirin, at low doses increases cell viability by decreasing inflammation and oxidative stress, preventing the deleterious effects of the Aβ_1-42 peptide on astrocytes in primary culture. The use of low doses of aspirin may be more suitable for Alzheimer's disease.

NADPH oxidases in oxidant production by microglia: activating receptors, pharmacology and association with disease

Microglia are the resident immune cells of the CNS and constitute a self-sustaining population of CNS-adapted tissue macrophages. As mononuclear phagocytic cells, they express high levels of superoxide-producing NADPH oxidases (NOX). The sole function of the members of the NOX family is to generate reactive oxygen species (ROS) that are believed to be important in CNS host defence and in the redox signalling circuits that shape the different activation phenotypes of microglia. NOX are also important in pathological conditions, where over-generation of ROS contributes to neuronal loss via direct oxidative tissue damage or disruption of redox signalling circuits. In this review, we assess the evidence for involvement of NOX in CNS physiopathology, with particular emphasis on the most important surface receptors that lead to generation of NOX-derived ROS. We evaluate the potential significance of the subcellular distribution of NOX isoforms for redox signalling or release of ROS to the extracellular medium. Inhibitory mechanisms that have been reported to restrain NOX activity in microglia and macrophages in vivo are also discussed. We provide a critical appraisal of frequently used and recently developed NOX inhibitors. Finally, we review the recent literature on NOX and other sources of ROS that are involved in activation of the inflammasome and discuss the potential influence of microglia-derived oxidants on neurogenesis, neural differentiation and culling of surplus progenitor cells. The degree to which excessive, badly timed or misplaced NOX activation in microglia may affect neuronal homeostasis in physiological or pathological conditions certainly merits further investigation.

LINKED ARTICLES

This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc.

Levetiracetam synergises with common analgesics in producing antinociception in a mouse model of painful diabetic neuropathy

Painful diabetic neuropathy is difficult to treat. Single analgesics often have insufficient efficacy and poor tolerability. Combination therapy may therefore be of particular benefit, because it might provide optimal analgesia with fewer adverse effects. This study aimed to examine the type of interaction between levetiracetam, a novel anticonvulsant with analgesic properties, and commonly used analgesics (ibuprofen, aspirin and paracetamol) in a mouse model of painful diabetic neuropathy. Diabetes was induced in C57BL/6 mice with a single high dose of streptozotocin, applied intraperitoneally (150 mg/kg). Thermal (tail-flick test) and mechanical (electronic von Frey test) nociceptive thresholds were measured before and three weeks after diabetes induction. The antinociceptive effects of orally administered levetiracetam, analgesics, and their combinations were examined in diabetic mice that developed thermal/mechanical hypersensitivity. In combination experiments, the drugs were co-administered in fixed-dose fractions of single drug ED50 and the type of interaction was determined by isobolographic analysis. Levetiracetam (10-100 mg/kg), ibuprofen (2-50 mg/kg), aspirin (5-75 mg/kg), paracetamol (5-100 mg/kg), and levetiracetam-analgesic combinations produced significant, dose-dependent antinociceptive effects in diabetic mice in both tests. In the tail-flick test, isobolographic analysis revealed 15-, and 19-fold reduction of doses of both drugs in the combination of levetiracetam with aspirin/ibuprofen, and paracetamol, respectively. In the von Frey test, approximately 7- and 9-fold reduction of doses of both drugs was detected in levetiracetam-ibuprofen and levetiracetam-aspirin/levetiracetam-paracetamol combinations, respectively. These results show synergism between levetiracetam and ibuprofen/aspirin/paracetamol in a model of painful diabetic neuropathy and might provide a useful approach to the treatment of patients suffering from painful diabetic neuropathy.

In vitro models for neurotoxicology research

The nervous system has a highly complex organization, including many cell types with multiple functions, with an intricate anatomy and unique structural and functional characteristics; the study of its (dys)functionality following exposure to xenobiotics, neurotoxicology, constitutes an important issue in neurosciences.

Mitochondrial dynamics modulate the expression of pro-inflammatory mediators in microglial cells

Over-activation of microglia cells in the brain contributes to neurodegenerative processes promoted by the production of various neurotoxic factors including pro-inflammatory cytokines and nitric oxide. Recently, accumulating evidence has suggested that mitochondrial dynamics are an important constituent of cellular quality control and function. However, the role of mitochondrial dynamics in microglial activation is still largely unknown. In this study, we determined whether mitochondrial dynamics are associated with the production of pro-inflammatory mediators in lipopolysaccharide (LPS)-stimulated immortalization of murine microglial cells (BV-2) by a v-raf/v-myc carrying retrovirus (J2). Excessive mitochondrial fission was observed in lentivirus-transfected BV-2 cells stably expressing DsRed2-mito following LPS stimulation. Furthermore, mitochondrial localization of dynamin-related protein 1 (Drp1) (a key regulator of mitochondrial fission) was increased and accompanied by de-phosphorylation of Ser637 in Drp1. Interestingly, inhibition of LPS-induced mitochondrial fission and reactive oxygen species (ROS) generation by Mdivi-1 and Drp1 knock-down attenuated the production of pro-inflammatory mediators via reduced nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and mitogen-activated protein kinase (MAPK) signaling. Our results demonstrated for the first time that mitochondrial fission regulates mitochondrial ROS production in activated microglial cells and influences the expression of pro-inflammatory mediators through the activation of NF-κB and MAPK. We therefore suggest that mitochondrial dynamics may be essential for understanding pro-inflammatory mediator expression in activated microglial cells. This could represent a new therapeutic approach for preventing neurodegenerative diseases.

Nitric oxide in neurodegeneration: potential benefits of non-steroidal anti-inflammatories

The cellular messenger nitric oxide (NO) has been linked to neurodegenerative disorders due to the increased expression of the enzymes that catalyze its synthesis in postmortem tissues derived from sufferers of these diseases. Nitrated proteins have also been detected in these samples, revealing that NO is biologically active in regions damaged during neurodegeneration. Modulation of NO levels has been reported not only in the neurons of the central nervous system, but also in the glial cells (microglia and astroglia) activated during the neuroinflammatory response. Neuroinflammation has been found in some neurodegenerative conditions, and inhibition of these neuroinflammatory signals has been shown to delay the progress of such disorders. Thus NO and the pathways triggering its release are emerging as an important research focus in the search for strategies to prevent, halt or cure neurodegenerative diseases.