Search

Valproic acid (VPA)—a short branched chain fatty acid (BCFA), is widely recognized as an anticonvulsant and a mood‐stabilizing drug, but various adverse effects of VPA have also been investigated. However, the impact of BCFAs aggregation on brain cells, in the pathogenesis of neurodegeneration remains elusive. The objective of this study is to understand the cellular mechanisms underlying VPA‐induced neuronal cell death mediated by oxidative stress, and the neuroprotective role of exogenous melatonin treatment on VPA‐induced cell death. Neurotoxicity of VPA and protective role exerted by melatonin were assessed in vitro in SH‐SY5Y cells and in vivo in the cerebral cortex and cerebellum regions of Wistar rat brain. The results show that melatonin pre‐treatment protects the cells from VPA‐induced toxicity by exerting an anti‐apoptotic and anti‐inflammatory effect by regulating apoptotic proteins and pro‐inflammatory cytokines. The findings of the present study emphasize novel insights of melatonin as a supplement for the prevention and treatment of neuronal dysfunction induced by VPA. [ABSTRACT FROM AUTHOR]

Phytanic acid, a saturated branched chain fatty acid and a major constituent of human diet, is predominantly found in dairy products, meat, and fish. It is a degradation product from the phytol side chain of chlorophyll. Degradation of PA is known to occur mainly in peroxisomes via α-oxidation and in mitochondria via β-oxidation. Due to its β-methyl group present at the 3-position of the carbon atoms, PA cannot be β-oxidized. Although alteration in the metabolism of PA may play an important role in neurodegeneration, the exact mechanism behind it remains to be evaluated. In this study, we have described the potential of PA to induce neurotoxicity as an in vitro model (neuronal cell line, SH-SY5Y cells). Cells were pretreated with melatonin (10 μM) for 1 h followed by with and without PA (100 μM) for 24 h. In the present study, our data has confirmed that PA markedly increased both intracellular reactive oxygen species and reactive nitrogen species levels. Our results have shown that PA treatment did not induce cell death by cleavage of caspase-3/PARP-1 mediated by mitochondria through intrinsic pathways; however, PA induced nitric oxide-dependent apoptosis in SH-SY5Y cells. Additionally, melatonin pretreatment reduced the cell death in SH-SY5Y cells. Melatonin also effectively exerted an antiapoptotic and anti-inflammatory action by regulating Bax, Bcl-2, p-NFκB, and iNOS expressions in SH-SY5Y cells. These results suggested that melatonin acted as an antioxidative and antiapoptotic agent by modulating ROS, apoptotic proteins, and inflammatory responses under BCFA-induced neurotoxic conditions. The protective effects of melatonin depend on direct scavenging activity of free radicals and indirect antioxidant effects. Further deciphering of the cellular and molecular mechanism associated with neuroprotection by melatonin is warranted in BCFA-induced neurotoxicity. [ABSTRACT FROM AUTHOR]

Oxaliplatin (Oxa) treatment to SH-SY5Y human neuroblastoma cells has been shown by previous studies to induce oxidative stress, which in turn modulates intracellular signaling cascades resulting in cell death. While this phenomenon of Oxa-induced neurotoxicity is known, the underlying mechanisms involved in this cell death cascade must be clarified. Moreover, there is still little known regarding the roles of neuronal mitochondria and cytosolic compartments in mediating Oxa-induced neurotoxicity. With a better grasp of the mechanisms driving neurotoxicity in Oxa-treated SH-SY5Y cells, we can then identify certain pathways to target in protecting against neurotoxic cell damage. Therefore, the purpose of this study was to determine whether one such agent, melatonin (Mel), could confer protection against Oxa-induced neurotoxicity in SH-SY5Y cells. Results from the present study found Oxa to significantly reduce SH-SY5Y cell viability in a dose-dependent manner. Alternatively, we found Mel pre-treatment to SH-SY5Y cells to attenuate Oxa-induced toxicity, resulting in a markedly increased cell viability. Mel exerted its protective effects by regulating reactive oxygen species (ROS) production and reducing superoxide radicals inside Oxa-exposed. In addition, we observed pre-treatment with Mel to rescue Oxa-treated cells by protecting mitochondria. As Oxa-treatment alone decreases mitochondrial membrane potential (Δψm), resulting in an altered Bcl-2/Bax ratio and release of sequestered cytochrome c, so Mel was shown to inhibit these pathways. Mel was also found to inhibit proteolytic activation of caspase 3, inactivation of Poly (ADP Ribose) polymerase, and DNA damage, thereby allowing SH-SY5Y cells to resist apoptotic cell death. Collectively, our results suggest a role for melatonin in reducing Oxa induced neurotoxicity. Further studies exploring melatonin’s protective effects may prove successful in eliciting pathways to further alter the neurotoxic pathways of platinum compounds in cancer treatment. [ABSTRACT FROM AUTHOR]

• Aβ (1-42) significantly increases AChE activity, induces of ER stress and apoptosis. • Aβ (1-42) treatment causes increase in oxidative stress and neuronal degeneration. • Aβ (1-42) treatment also results in activation of microglial cells. • Salubrinal attenuates Aβ (1-42) -induced ER and oxidative stress and apoptosis. • Salubrinal attenuates Aβ (1-42) -induced neurodegeneration and microglial activation. Amyloid-β (Aβ) accumulation in the brain is a pathological hallmark of Alzheimer's disease (AD). Endoplasmic reticulum (ER) stress has been implicated in aetiology of neurodegenerative disorders. We studied the involvement of ER stress in Aβ-induced neuronal degeneration in rat brain to correlate it with cellular and molecular modifications in Aβ-induced Alzheimer's like neuropathological process. Aβ (1-42) (5 μg) was administered by bilateral intracerebroventricular (icv) injection in the brain of adult male Wistar rats. Acetylcholinesterase (AChE) activity and histological alterations were observed in different brain regions. ER stress-associated proteins- glucose regulated protein-78 (GRP78), eukaryotic translation initiation factor-2α (eIF2α) and growth arrest and DNA damage-inducible protein-153 (GADD153), neuronal marker- microtubule associated protein-2 (MAP-2) and microglial protein- ionized calcium binding adaptor molecule-1 (Iba-1) were measured by western blot. Reduced glutathione (GSH), nitrite level and levels of caspase-12 and caspase-3 were also measured. ER stress inhibitor, salubrinal (1 mg/kg, intraperitoneally, ip) was used to assess the specific role of ER stress. Aβ (1-42) -induced increase in AChE activity, GRP78 and GADD protein levels, dephosphorylation of eIF2-α and caspase-12 and caspase-3 levels and decrease in GSH and MAP-2 levels were attenuated by salubrinal. Increase in Iba-1 protein and nitrite levels after Aβ (1-42) administration were partially attenuated by salubrinal. Aβ (1-42) -induced histological alterations were correlated with findings of ER stress. Results of present study implicate ER stress as a potential molecular mechanism in Aβ-induced Alzheimer's like neuropathology which could serve as surrogate biomarker for study of AD progression and efficacy of therapeutic interventions for AD management. [ABSTRACT FROM AUTHOR]

Oxidative stress-related inflammation and apoptosis are important pathogenic consequences, which result in acute pulmonary toxicity. Bleomycin (BLM) is used to treat various forms of cancers. However, its prolonged administration is associated with major toxicity to respiratory system. We studied the effect of walnut ( Juglans regia) extract in a rat model of BLM-induced pulmonary toxicopathy. We also studied parameters of inflammation, apoptosis and oxidative stress in various groups of animals. Prophylactic treatment of total methanolic extract of walnut at the dose of 150 mg/kg b.w. was given per os to Wistar rats for 14 days prior to BLM exposure. A single intratracheal injection of BLM (10 U/kg b.w.) was administered on the eleventh day of the treatment. There was a marked increase in the hydroxyproline level, lipid peroxidation, nitric oxide production, and in the activities of xanthine oxidase and myeloperoxidase in the lung tissue in BLM-treated animals when compared to control animals. BLM also decreased the activities of antioxidant enzymes such as glutathione reductase and catalase and increased the lung inflammation and apoptosis by upregulating the NF-κB signaling pathway and caspase-3 expression. Treatment with walnut extract attenuated these changes in a significant manner. Walnut extract significantly modulated the lung injury as measured by markers of cellular injury such as lactate dehydrogenase and alkaline phosphatase, total cell count, total protein and reduced glutathione in bronchoalveolar lavage fluid. Histological findings supported the protective effects of walnut extract against BLM-induced lung injury. Walnut which has been shown to have numerous medicinally valuable constituents including ellagic acid showed efficacy in preventing the various toxicopathological effects of BLM in rat lungs. Overall, walnut extract decreases BLM-induced oxidative stress and lung inflammation by modulating the alveolar macrophage inflammatory response in rats and thus protecting them from the pathological effect of BLM. [ABSTRACT FROM AUTHOR]