Excessive production of inflammatory mediators such as nitric oxide (NO) and proinflammatory cytokines like tumour necrosis factor-alpha (TNF-α) from activated microglia contributes to uncontrolled inflammation in neurodegenerative diseases. This study investigated the protective role of five endophytic extracts (HAB16R12, HAB16R13, HAB16R14, HAB16R18 and HAB8R24) against LPS-induced inflammatory events in vitro. These endophytic extracts were previously found to exhibit potent neuroprotective effect against LPS-challenged microglial cells.
Negletein has been shown to have therapeutic potential for inflammation-associated diseases, but its effect on neurite outgrowth is still unknown. The present study showed that negletein alone did not trigger PC12 cells to differentiate and extend neurites. When compared with the cells in the untreated control, a significant (P
Several lines of evidence indicate that beta amyloid (β-A) production, neurofibrillary tangles and neuroinflammation are interrelated in the pathogenesis of Alzheimer's disease (AD). AD is associated with enhanced β-A production and accumulation resulting in neuroinflammation probably via activation of lipoxygenase (LOX) and cyclooxygenase (COX) pathways. Therefore, the present study was designed to investigate the role of LOX and COX inhibitors (zafirlukast and valdecoxib) in amyloidogenesis in β-A1-42 oligomer induced experimental AD in rats. The behavioral activities were assessed using actophotometer, novel object recognition test (ORT), Morris water maze (MWM) followed by biochemical assessments, determination of proinflammatory cytokines and mediators (TNF-α, IL-1β and PGE2), β-A1-42 levels and histopathological analysis. ICV administration of β-A1-42 oligomer produced significant impairment in memory consolidation. In addition to this significant increase in mito-oxidative stress, neuroinflammatory markers, acetylcholinesterase (AChE) toxicity, β-A1-42 level, neuronal cell death and neuroinflammation are more profound in β-A1-42 oligomer treated AD rats. Administration of zafirlukast (15 and 30mg/kg), and valdecoxib (5 and 10mg/kg) significantly improved the behavioral performances and showed significant reversal of mito-oxidative damage declining the neuroinflammation in β-A1-42 oligomer treated rats. Furthermore, more profound effects were observed at the sub-therapeutic dose combination of zafirlukast (15mg/kg) and valdecoxib (5mg/kg). The results of the present study indicate that protective effects of zafirlukast and valdecoxib are achieved through the blockade of release of LOX and COX metabolites therefore, representing a new therapeutic target for treating AD and other neurodegenerative disorders.
This study evaluated the neuroprotective effect of intrathecally infused paclitaxel in the prevention of motoneuron death and mitochondrial dysfunction following brachial plexus avulsion injury.
Increased oxidative stress and mitochondrial dysfunction have been identified as common pathophysiological phenomena associated with neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's disease (HD). As the age-related decline in the production of melatonin may contribute to increased levels of oxidative stress in the elderly, the role of this neuroprotective agent is attracting increasing attention. Melatonin has multiple actions as a regulator of antioxidant and prooxidant enzymes, radical scavenger and antagonist of mitochondrial radical formation. The ability of melatonin and its kynuramine metabolites to interact directly with the electron transport chain by increasing the electron flow and reducing electron leakage are unique features by which melatonin is able to increase the survival of neurons under enhanced oxidative stress. Moreover, antifibrillogenic actions have been demonstrated in vitro, also in the presence of profibrillogenic apoE4 or apoE3, and in vivo, in a transgenic mouse model. Amyloid-beta toxicity is antagonized by melatonin and one of its kynuramine metabolites. Cytoskeletal disorganization and protein hyperphosphorylation, as induced in several cell-line models, have been attenuated by melatonin, effects comprising stress kinase downregulation and extending to neurotrophin expression. Various experimental models of AD, PD and HD indicate the usefulness of melatonin in antagonizing disease progression and/or mitigating some of the symptoms. Melatonin secretion has been found to be altered in AD and PD. Attempts to compensate for age- and disease-dependent melatonin deficiency have shown that administration of this compound can improve sleep efficiency in AD and PD and, to some extent, cognitive function in AD patients. Exogenous melatonin has also been reported to alleviate behavioral symptoms such as sundowning. Taken together, these findings suggest that melatonin, its analogues and kynuric metabolites may have potential value in prevention and treatment of AD and other neurodegenerative disorders.
Parkinson's disease (PD) is the most common neurodegenerative movement disorder with obscure etiology and no disease-modifying therapy to date. Hence, novel, safe, and low cost-effective approaches employing medicinal plants are currently receiving increased attention. A growing body of evidence has revealed that cinnamon, being widely used as a spice of unique flavor and aroma, may exert neuroprotective effects in several neurodegenerative diseases, including PD. In vitro evidence has indicated that the essential oils of Cinnamomum species, mainly cinnamaldehyde and sodium benzoate may protect against oxidative stress-induced cell death, reactive oxygen species generation, and autophagy dysregulation, thus acting in a potentially neuroprotective manner. In vivo evidence has demonstrated that oral administration of cinnamon powder and sodium benzoate may protect against dopaminergic cell death, striatal neurotransmitter dysregulation, and motor deficits in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine mouse models of PD. The underlying mechanisms of its action include autophagy regulation, antioxidant effects, upregulation of Parkin, DJ-1, glial cell line-derived neurotrophic factor, as well as modulation of the TLR/NF-κB pathway and inhibition of the excessive proinflammatory responses. In addition, in vitro and in vivo studies have shown that cinnamon extracts may affect the oligomerization process and aggregation of α-synuclein. Herein, we discuss recent evidence on the novel therapeutic opportunities of this phytochemical against PD, indicating additional mechanistic aspects that should be explored, and potential obstacles/limitations that need to be overcome, for its inclusion in experimental PD therapeutics.
Catalpol isolated from Rehmannia glutinosa is a potent antioxidant and investigated against many disorders. This review appraises the key molecular pathways of catalpol against diabetes mellitus and its complications. Multiple search engines including Google Scholar, PubMed, and Science Direct were used to retrieve publications containing the keywords "Catalpol", "Type 1 diabetes mellitus", "Type 2 diabetes mellitus", and "diabetic complications". Catalpol promotes IRS-1/PI3K/AKT/GLUT2 activity and suppresses Phosphoenolpyruvate carboxykinase (PEPCK) and Glucose 6-phosphatase (G6Pase) expression in the liver. Catalpol induces myogenesis by increasing MyoD/MyoG/MHC expression and improves mitochondria function through the AMPK/PGC-1α/PPAR-γ and TFAM signaling in skeletal muscles. Catalpol downregulates the pro-inflammatory markers and upregulates the anti-inflammatory markers in adipose tissues. Catalpol exerts antioxidant properties through increasing superoxide dismutase (sod), catalase (cat), and glutathione peroxidase (gsh-px) activity in the pancreas and liver. Catalpol has been shown to have anti-oxidative, anti-inflammatory, anti-apoptosis, and anti-fibrosis properties that in turn bring beneficial effects in diabetic complications. Its nephroprotective effect is related to the modulation of the AGE/RAGE/NF-κB and TGF-β/smad2/3 pathways. Catalpol produces a neuroprotective effect by increasing the expression of protein Kinase-C (PKC) and Cav-1. Furthermore, catalpol exhibits a cardioprotective effect through the apelin/APJ and ROS/NF-κB/Neat1 pathway. Catalpol stimulates proliferation and differentiation of osteoblast cells in high glucose condition. Lastly, catalpol shows its potential in preventing neurodegeneration in the retina with NF-κB downregulation. Overall, catalpol exhibits numerous beneficial effects on diabetes mellitus and diabetic complications.
Alzheimer's disease (AD) is the second most occurring neurological disorder after stroke and is associated with cerebral hypoperfusion, possibly contributing to cognitive impairment. In the present study, neuroprotective and anti-AD effects of embelin were evaluated in chronic cerebral hypoperfusion (CCH) rat model using permanent bilateral common carotid artery occlusion (BCCAO) method. Rats were administered with embelin at doses of 0.3, 0.6 or 1.2 mg/kg (i.p) on day 14 post-surgery and tested in Morris water maze (MWM) followed by electrophysiological recordings to access cognitive abilities and synaptic plasticity. The hippocampal brain regions were extracted for gene expression and neurotransmitters analysis. Treatment with embelin at the doses of 0.3 and 0.6 mg/kg significantly reversed the spatial memory impairment induced by CCH in rats. Embelin treatment has significantly protected synaptic plasticity impairment as assessed by hippocampal long-term potentiation (LTP) test. The mechanism of this study demonstrated that embelin treatment alleviated the decreased expression of BDNF, CREB1, APP, Mapt, SOD1 and NFκB mRNA levels caused by CCH rats. Furthermore, treatment with embelin demonstrated neuromodulatory activity by its ability to restore hippocampal neurotransmitters. Overall these data suggest that embelin improve memory and synaptic plasticity impairment in CCH rats and can be a potential drug candidate for neurodegenerative disease-related cognitive disorders.
Alzheimer's disease (AD) as a neurodegenerative brain disorder is the most common cause of dementia. To date, there is no causative treatment for AD and there are few preventive treatments either. The sphingosine-1-phosphate receptor modulator FTY720 (fingolimod) prevents lymphocytes from contributing to an autoimmune reaction and has been approved for multiple sclerosis treatment. In concert with other studies showing the anti-inflammatory and protective effect of FTY720 in some neurodegenerative disorders like ischemia, we have recently shown that FTY720 chronic administration prevents from impairment of spatial learning and memory in AD rats. Here FTY720 was examined on AD rats in comparison to the only clinically approved NMDA receptor antagonist, Memantine. Passive avoidance task showed significant memory restoration in AD animals received FTY720 comparable to Memantine. Upon gene profiling by QuantiGene Plex, this behavioral outcomes was concurrent with considerable alterations in some genes transcripts like that of mitogen activated protein kinases (MAPKs) and some inflammatory markers that may particularly account for the detected decline in hippocampal neural damage or memory impairment associated with AD. From a therapeutic standpoint, our findings conclude that FTY720 may suggest new opportunities for AD management probably based on several modulatory effects on genes involved in cell death or survival.
Glutamate is the major mediator of excitatory signals in the mammalian central nervous system. Extreme amounts of glutamate in the extracellular spaces can lead to numerous neurodegenerative diseases. We aimed to clarify the potential of the following vitamin E isomers, tocotrienol-rich fraction (TRF) and α-tocopherol (α-TCP), as potent neuroprotective agents against glutamate-induced injury in neuronal SK-N-SH cells. Cells were treated before and after glutamate injury (pre- and post-treatment, respectively) with 100-300 ng/ml TRF/α-TCP. Exposure to 120 mM glutamate significantly reduced cell viability to 76% and 79% in the pre- and post-treatment studies, respectively; however, pre- and post-treatment with TRF/α-TCP attenuated the cytotoxic effect of glutamate. Compared to the positive control (glutamate-injured cells not treated with TRF/α-TCP), pre-treatment with 100, 200, and 300 ng/ml TRF significantly improved cell viability following glutamate injury to 95.2%, 95.0%, and 95.6%, respectively (p<0.05).The isomers not only conferred neuroprotection by enhancing mitochondrial activity and depleting free radical production, but also increased cell viability and recovery upon glutamate insult. Our results suggest that vitamin E has potent antioxidant potential for protecting against glutamate injury and recovering glutamate-injured neuronal cells. Our findings also indicate that both TRF and α-TCP could play key roles as anti-apoptotic agents with neuroprotective properties.