Resveratrol Protects from Toxin-Induced Parkinsonism: Plethora of Proofs Hitherto Petty Translational Value

Plausible Role of Mitochondrial DNA Copy Number in Neurodegeneration-a Need for Therapeutic Approach in Parkinson's Disease (PD)

Parkinson's disease (PD) is an advancing age-associated progressive brain disorder which has various diverse factors, among them mitochondrial dysfunction involves in dopaminergic (DA) degeneration. Aging causes a rise in mitochondrial abnormalities which leads to structural and functional modifications in neuronal activity and cell death in PD. This ends in deterioration of mitochondrial function, mitochondrial alterations, mitochondrial DNA copy number (mtDNA CN) and oxidative phosphorylation (OXPHOS) capacity. mtDNA levels or mtDNA CN in PD have reported that mtDNA depletion would be a predisposing factor in PD pathogenesis. To maintain the mtDNA levels, therapeutic approaches have been focused on mitochondrial biogenesis in PD. The depletion of mtDNA levels in PD can be influenced by autophagic dysregulation, apoptosis, neuroinflammation, oxidative stress, sirtuins, and calcium homeostasis. The current review describes the regulation of mtDNA levels and discusses the plausible molecular pathways in mtDNA CN depletion in PD pathogenesis. We conclude by suggesting further research on mtDNA depletion which might show a promising effect in predicting and diagnosing PD.

The Role of PGC-1α-Mediated Mitochondrial Biogenesis in Neurons

Neurons are highly dependent on mitochondrial ATP production and Ca²⁺ buffering. Neurons have unique compartmentalized anatomy and energy requirements, and each compartment requires continuously renewed mitochondria to maintain neuronal survival and activity. Peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α) is a key factor in the regulation of mitochondrial biogenesis. It is widely accepted that mitochondria are synthesized in the cell body and transported via axons to the distal end. However, axonal mitochondrial biogenesis is necessary to maintain axonal bioenergy supply and mitochondrial density due to limitations in mitochondrial axonal transport rate and mitochondrial protein lifespan. In addition, impaired mitochondrial biogenesis leading to inadequate energy supply and neuronal damage has been observed in neurological disorders. In this review, we focus on the sites where mitochondrial biogenesis occurs in neurons and the mechanisms by which it maintains axonal mitochondrial density. Finally, we summarize several neurological disorders in which mitochondrial biogenesis is affected.

Antiparkinsonian Agents in Investigational Polymeric Micro- and Nano-Systems

Parkinson's disease (PD) is a devastating neurodegenerative disease characterized by progressive destruction of dopaminergic tissue in the central nervous system (CNS). To date, there is no cure for the disease, with current pharmacological treatments aimed at controlling the symptoms. Therefore, there is an unmet need for new treatments for PD. In addition to new therapeutic options, there exists the need for improved efficiency of the existing ones, as many agents have difficulties in crossing the blood-brain barrier (BBB) to achieve therapeutic levels in the CNS or exhibit inappropriate pharmacokinetic profiles, thereby limiting their clinical benefits. To overcome these limitations, an interesting approach is the use of drug delivery systems, such as polymeric microparticles (MPs) and nanoparticles (NPs) that allow for the controlled release of the active ingredients targeting to the desired site of action, increasing the bioavailability and efficacy of treatments, as well as reducing the number of administrations and adverse effects. Here we review the polymeric micro- and nano-systems under investigation as potential new therapies for PD.

Neuroprotection by Mucuna pruriens in Neurodegenerative Diseases

The medicinal plant Mucuna pruriens (Fabaceae) is widely known for its anti-oxidative and anti-inflammatory properties. It is a well-established drug in Ayurveda and has been widely used for the treatment of neurological disorders and male infertility for ages. The seeds of the plant have potent medicinal value and its extract has been tested in different models of neurodegenerative diseases, especially Parkinson's disease (PD). Apart from PD, Mucuna pruriens is now being studied in models of other nervous systems disorders such as Alzheimer's disease (AD), Amyotrophic lateral sclerosis (ALS) and stroke because of its neuroprotective importance. This review briefly discusses the pathogenesis of PD, AD, ALS and stroke. It aims to summarize the medicinal importance of Mucuna pruriens in treatment of these diseases, and put forward the potential targets where Mucuna pruriens can act for therapeutic interventions. In this review, the effect of Mucuna pruriens on ameliorating the neurodegeneration evident in PD, AD, ALS and stroke is briefly discussed. The potential targets for neuroprotection by the plant are delineated, which can be studied further to validate the hypothesis regarding the use of Mucuna pruriens for the treatment of these diseases.

Separation and Identification of Resveratrol Butyrate Ester Complexes and Their Bioactivity in HepG2 Cell Models

Resveratrol butyrate ester (RBE) complexes have demonstrated higher antioxidant capacity and anti-fat accumulation activity in previous studies. In this study, silica gel, high-performance liquid chromatography, and 1H nuclear magnetic resonance were used for separation and identification of RBE complex components. With the exception of resveratrol, five different structures of ester derivatives were separated from silica gel: 3,4′-di-O-butanoylresveratrol (ED2, 18.8%), 3-O-butanoylresveratrol (ED4, 35.7%), 4′-O-butanoylresveratrol (ED5, 4.4%), 3,5,4′-tri-O-butanoylresveratrol (ED6, 1.5%), and 3,5-di-O-butanoylresveratrol (ED7, 0.7%). Among the ester derivatives obtained, ED2 and ED4 were the main ester derivatives in the RBE complex. Thus, the cellular antioxidant activities of the RBE mixture, ED2, and ED4 were evaluated. Results showed that the antioxidant capacity of ED2 and ED4 was higher than that of the RBE mixture, demonstrating that the number and position of butyrate esterification sites are related to cell survival rate and antioxidant capacity. This study is the first to report the successful isolation, structural identification, and cellular biological antioxidant activity of RBE complex derivatives, which are key characteristics for the potential practical application of RBE complexes.

Dopaminergic Axons: Key Recitalists in Parkinson's Disease

Parkinson's disease (PD) is associated with dopamine depletion in the striatum owing to the selective and progressive loss of the nigrostriatal dopaminergic neurons, which results in motor dysfunction and secondary clinical manifestations. The dopamine level in the striatum is preserved because of the innervation of the substantia nigra (SN) dopaminergic neurons into it. Therefore, protection of the SN neurons is crucial for maintaining the dopamine level in the striatum and for ensuring the desired motor coordination. Several strategies have been devised to protect the degenerating dopaminergic neurons or to restore the dopamine levels for treating PD. Most of the methods focus exclusively on preventing cell body death in the neurons. Although advances have been made in understanding the disease, the search for disease-modifying drugs is an ongoing process. The present review describes the evidence from studies involving patients with PD as well as PD models that axon terminals are highly vulnerable to exogenous and endogenous insults and degenerate at the early stage of the disease. Impairment of mitochondrial dynamics, Ca²⁺ homeostasis, axonal transport, and loss of plasticity of axon terminals appear before the neuronal degeneration in PD. Furthermore, distortion of synaptic morphology and reduction of postsynaptic dendritic spines are the neuropathological hallmarks of early-stage disease. Thus, the review proposes a shift in focus from discerning the mechanism of neuronal cell body loss and targeting it to an entirely different approach of preventing axonal degeneration. The review also suggests appropriate strategies to prevent the loss of synaptic terminals, which could induce regrowth of the axon and its auxiliary fibers and might offer relief from the symptomatic features of PD.

Targeting autophagy using small-molecule compounds to improve potential therapy of Parkinson's disease

Parkinson's disease (PD), known as one of the most universal neurodegenerative diseases, is a serious threat to the health of the elderly. The current treatment has been demonstrated to relieve symptoms, and the discovery of new small-molecule compounds has been regarded as a promising strategy. Of note, the homeostasis of the autolysosome pathway (ALP) is closely associated with PD, and impaired autophagy may cause the death of neurons and thereby accelerating the progress of PD. Thus, pharmacological targeting autophagy with small-molecule compounds has been drawn a rising attention so far. In this review, we focus on summarizing several autophagy-associated targets, such as AMPK, mTORC1, ULK1, IMPase, LRRK2, beclin-1, TFEB, GCase, ERRα, C-Abelson, and as well as their relevant small-molecule compounds in PD models, which will shed light on a clue on exploiting more potential targeted small-molecule drugs tracking PD treatment in the near future.

Immobilized Lipase Based on Hollow Mesoporous Silicon Spheres for Efficient Enzymatic Synthesis of Resveratrol Ester Derivatives

Enzymatic esterification of resveratrol is crucial for its potential application in lipophilic foods and drugs. However, the poor activity of the free enzyme hinders the reaction. In this work, the highly efficient enzymatic synthesis of resveratrol ester derivatives was achieved by immobilized lipase on hydrophobic modified hollow mesoporous silicon spheres (HMSS-C₈). We preliminarily explored the use of Candida sp. 99-125 lipase (CSL) for the acylation of resveratrol, with a regioselectivity toward 3-OH- over 4'-OH-acylation. HMSS-C₈ provided ideal accommodation for CSL with a loading capacity of up to 652 mg/g. The catalytic efficiency of CSL@HMSS-C₈ was 15 times higher than that of free CSL, and the conversion of resveratrol reached 98.7% within only 2 h, which is the fastest value recorded in the current literature. After 10 cycles, the conversion remained up to 86.3%. Benefiting from better lipid solubility, the relative oxidation stability index values of oil containing monoester derivatives were 43.1%-68.8% and 23.9%-33.2% higher than that of refined oil and oil containing resveratrol, respectively. This research provides a new pathway for efficient enzymatic synthesis of resveratrol ester derivatives and demonstrates the potential application of resveratrol monoester derivatives as a group of excellent lipid-soluble antioxidants.

The neuroprotective effects of polyphenols, their role in innate immunity and the interplay with the microbiota

Neurodegenerative disorders, particularly in the elderly population, represent one of the most pressing social and health-care problems in the world. Besides the well-established role of both oxidative stress and inflammation, alterations of the immune response have been found to be closely linked to the development of neurodegenerative diseases. Interestingly, various scientific evidence reported that an altered gut microbiota composition may contribute to the development of neuroinflammatory disorders. This leads to the proposal of the concept of the gut-brain-immune axis. In this scenario, polyphenols play a pivotal role due to their ability to exert neuroprotective, immunomodulatory and microbiota-remodeling activities. In the present review, we summarized the available literature to provide a scientific evidence regarding this neuroprotective and immunomodulatory effects and the interaction with gut microbiota of polyphenols and, the main signaling pathways involved that can explain their potential therapeutic application in neurodegenerative diseases.

Resveratrol Butyrate Esters Inhibit BPA-Induced Liver Damage in Male Offspring Rats by Modulating Antioxidant Capacity and Gut Microbiota

Resveratrol can affect the physiology or biochemistry of offspring in the maternal-fetal animal model. However, it exhibits low bioavailability in humans and animals. Fifteen-week SD pregnant female rats were orally administered bisphenol A (BPA) and/or resveratrol butyrate ester (RBE), and the male offspring rats (n = 4-8 per group) were evaluated. The results show that RBE treatment (BPA + R30) compared with the BPA group can reduce the damage caused by BPA (p < 0.05). RBE enhanced the expression of selected genes and induced extramedullary hematopoiesis and mononuclear cell infiltration. RBE increased the abundance of S24-7 and Adlercreutzia in the intestines of the male offspring rats, as well as the concentrations of short-chain fatty acids (SCFAs) in the feces. RBE also increased the antioxidant capacity of the liver by inducing Nrf2, promoting the expression of HO-1, SOD, and CAT. It also increased the concentration of intestinal SCFAs, enhancing the barrier formed by intestinal cells, thereby preventing BPA-induced metabolic disruption in the male offspring rats, and reduced liver inflammation. This study identified a potential mechanism underlying the protective effects of RBE against the liver damage caused by BPA exposure during the peri-pregnancy period, and the influence of the gut microbiota on the gut-liver axis in the offspring.

PPARγ/PGC1α signaling as a potential therapeutic target for mitochondrial biogenesis in neurodegenerative disorders

Neurodegenerative diseases represent some of the most devastating neurological disorders, characterized by progressive loss of the structure and function of neurons. Current therapy for neurodegenerative disorders is limited to symptomatic treatment rather than disease modifying interventions, emphasizing the desperate need for improved approaches. Abundant evidence indicates that impaired mitochondrial function plays a crucial role in pathogenesis of many neurodegenerative diseases and so biochemical factors in mitochondria are considered promising targets for pharmacological-based therapies. Peroxisome proliferator-activated receptors-γ (PPARγ) are ligand-inducible transcription factors involved in regulating various genes including peroxisome proliferator-activated receptor gamma co-activator-1 alpha (PGC1α). This review summarizes the evidence supporting the ability of PPARγ-PGC1α to coordinately up-regulate the expression of genes required for mitochondrial biogenesis in neurons and provide directions for future work to explore the potential benefit of targeting mitochondrial biogenesis in neurodegenerative disorders. We have highlighted key roles of NRF2, uncoupling protein-2 (UCP2), and paraoxonase-2 (PON2) signaling in mediating PGC1α-induced mitochondrial biogenesis. In addition, the status of PPARγ modulators being used in clinical trials for Parkinson's disease (PD), Alzheimer's disease (AD) and Huntington's disease (HD) has been compiled. The overall purpose of this review is to update and critique our understanding of the role of PPARγ-PGC1α-NRF2 in the induction of mitochondrial biogenesis together with suggestions for strategies to target PPARγ-PGC1α-NRF2 signaling in order to combat mitochondrial dysfunction in neurodegenerative disorders.

Role of medicinal plants against neurodegenerative diseases

Diseases with a significant loss of neurons, structurally and functionally are termed as neurodegenerative diseases. Due to the present therapeutic interventions and progressive nature of diseases, a variety of side effects have risen up, thus leading the patients to go for an alternative medication. The role of medicinal plants in such cases has been beneficial because of their exhibition via different cellular and molecular mechanisms. Alleviation in inflammatory responses, suppression of the functionary aspect of pro-inflammatory cytokines like a tumor, improvement in antioxidative properties is among few neuroprotective mechanisms of traditional plants. Variation in transcription and transduction pathways play a vital role in the preventive measures of plants in such diseases. Neurodegenerative diseases are generally caused by depletion of proteins, oxidative and inflammatory stress, environmental changes and so on, with aging being the most important cause. Natural compounds can be used in order to treat neurodegenerative diseases Medicinal plants such as Ginseng, Withania somnifera, Bacopa monnieri, Ginkgo biloba, etc. are some of the medicinal plants for prevention of neurological symptoms. This review deals with the use of different medicinal plants for the prevention of neurodegenerative diseases.

Swertiamarin from Enicostemma littorale, counteracts PD associated neurotoxicity via enhancement α-synuclein suppressive genes and SKN-1/NRF-2 activation through MAPK pathway

The elusive targets and the multifactorial etiology of Parkinson's disease (PD) have hampered the discovery of a potent drug for PD. Furthermore, the presently available medications provide only symptomatic relief and have failed to mitigate the pathogenesis associated with PD. Therefore, the current study was aimed to evaluate the prospective of swertiamarin (SW), a secoiridoid glycoside isolated from a traditional medicinal plant, Enicostemma littorale Blume to ameliorate the characteristic features of PD in Caenorhabditis elegans. SW (25 μM) administration decreased the α-synuclein (α-syn) deposition, inhibited apoptosis and increased dopamine level mediated through upregulating the expression of genes linked to ceramide synthesis, mitochondrial morphology and function regulation, fatty acid desaturase genes along with stress responsive MAPK (mitogen-activated protein kinase) pathway genes. The neuroprotective effect of SW was evident from the robust reduction of 6-hydroxydopamine (6-OHDA) induced dopaminergic neurodegeneration independent of dopamine transporter (dat-1). SW mediated translational regulation of MAPK pathway genes was observed through increase expression of SKN-1 and GST-4. Further, in-silico molecular docking analysis of SW with C. elegans MEK-1 showed a promising binding affinity affirming the in-vivo results. Overall, these novel finding supports that SW is a possible lead for drug development against the multi- factorial PD pathologies.

In Search of Effective Treatments Targeting α-Synuclein Toxicity in Synucleinopathies: Pros and Cons

Parkinson's disease (PD), multiple system atrophy (MSA) and Dementia with Lewy bodies (DLB) represent pathologically similar, progressive neurodegenerative disorders characterized by the pathological aggregation of the neuronal protein α-synuclein. PD and DLB are characterized by the abnormal accumulation and aggregation of α-synuclein in proteinaceous inclusions within neurons named Lewy bodies (LBs) and Lewy neurites (LNs), whereas in MSA α-synuclein inclusions are mainly detected within oligodendrocytes named glial cytoplasmic inclusions (GCIs). The presence of pathologically aggregated α-synuclein along with components of the protein degradation machinery, such as ubiquitin and p62, in LBs and GCIs is considered to underlie the pathogenic cascade that eventually leads to the severe neurodegeneration and neuroinflammation that characterizes these diseases. Importantly, α-synuclein is proposed to undergo pathogenic misfolding and oligomerization into higher-order structures, revealing self-templating conformations, and to exert the ability of "prion-like" spreading between cells. Therefore, the manner in which the protein is produced, is modified within neural cells and is degraded, represents a major focus of current research efforts in the field. Given that α-synuclein protein load is critical to disease pathogenesis, the identification of means to limit intracellular protein burden and halt α-synuclein propagation represents an obvious therapeutic approach in synucleinopathies. However, up to date the development of effective therapeutic strategies to prevent degeneration in synucleinopathies is limited, due to the lack of knowledge regarding the precise mechanisms underlying the observed pathology. This review critically summarizes the recent developed strategies to counteract α-synuclein toxicity, including those aimed to increase protein degradation, to prevent protein aggregation and cell-to-cell propagation, or to engage antibodies against α-synuclein and discuss open questions and unknowns for future therapeutic approaches.

Phytochemicals Bridging Autophagy Induction and Alpha-Synuclein Degradation in Parkinsonism

Among nutraceuticals, phytochemical-rich compounds represent a source of naturally-derived bioactive principles, which are extensively studied for potential beneficial effects in a variety of disorders ranging from cardiovascular and metabolic diseases to cancer and neurodegeneration. In the brain, phytochemicals produce a number of biological effects such as modulation of neurotransmitter activity, growth factor induction, antioxidant and anti-inflammatory activity, stem cell modulation/neurogenesis, regulation of mitochondrial homeostasis, and counteracting protein aggregation through modulation of protein-folding chaperones and the cell clearing systems autophagy and proteasome. In particular, the ability of phytochemicals in restoring proteostasis through autophagy induction took center stage in recent research on neurodegenerative disorders such as Parkinson’s disease (PD). Indeed, autophagy dysfunctions and α-syn aggregation represent two interdependent downstream biochemical events, which concur in the parkinsonian brain, and which are targeted by phytochemicals administration. Therefore, in the present review we discuss evidence about the autophagy-based neuroprotective effects of specific phytochemical-rich plants in experimental parkinsonism, with a special focus on their ability to counteract alpha-synuclein aggregation and toxicity. Although further studies are needed to confirm the autophagy-based effects of some phytochemicals in parkinsonism, the evidence discussed here suggests that rescuing autophagy through natural compounds may play a role in preserving dopamine (DA) neuron integrity by counteracting the aggregation, toxicity, and prion-like spreading of α-syn, which remains a hallmark of PD.

Plant Extracts and Phytochemicals Targeting α-Synuclein Aggregation in Parkinson's Disease Models

α-Synuclein (α-syn) is a presynaptic protein that regulates the release of neurotransmitters from synaptic vesicles in the brain. α-Syn aggregates, including Lewy bodies, are features of both sporadic and familial forms of Parkinson's disease (PD). These aggregates undergo several key stages of fibrillation, oligomerization, and aggregation. Therapeutic benefits of drugs decline with disease progression and offer only symptomatic treatment. Novel therapeutic strategies are required which can either prevent or delay the progression of the disease. The link between α-syn and the etiopathogenesis and progression of PD are well-established in the literature. Studies indicate that α-syn is an important therapeutic target and inhibition of α-syn aggregation, oligomerization, and fibrillation are an important disease modification strategy. However, recent studies have shown that plant extracts and phytochemicals have neuroprotective effects on α-syn oligomerization and fibrillation by targeting different key stages of its formation. Although many reviews on the antioxidant-mediated, neuroprotective effect of plant extracts and phytochemicals on PD symptoms have been well-highlighted, the antioxidant mechanisms show limited success for translation to clinical studies. The identification of specific plant extracts and phytochemicals that target α-syn aggregation will provide selective molecules to develop new drugs for PD. The present review provides an overview of plant extracts and phytochemicals that target α-syn in PD and summarizes the observed effects and the underlying mechanisms. Furthermore, we provide a synopsis of current experimental models and techniques used to evaluate plant extracts and phytochemicals. Plant extracts and phytochemicals were found to inhibit the aggregation or fibril formation of oligomers. These also appear to direct α-syn oligomer formation into its unstructured form or promote non-toxic pathways and suggested to be valuable drug candidates for PD and related synucleinopathy. Current evidences from in vitro studies require confirmation in the in vivo studies. Further studies are needed to ascertain their potential effects and safety in preclinical studies for pharmaceutical/nutritional development of these phytochemicals or dietary inclusion of the plant extracts in PD treatment.

Cytochrome P450 2D6 and Parkinson's Disease: Polymorphism, Metabolic Role, Risk and Protection

Cytochrome P450 (CYP) 2D6 is one of the most highly active, oxidative and polymorphic enzymes known to metabolize Parkinsonian toxins and clinically established anti-Parkinson's disease (PD) drugs. Albeit CYP2D6 gene is not present in rodents, its orthologs perform almost the similar function with imprecise substrate and inhibitor specificity. CYP2D6 expression and catalytic activity are found to be regulated at every stage of the central dogma except replication as well as at the epigenetic level. CYP2D6 gene codes for a set of alternate splice variants that give rise to a range of enzymes possessing variable catalytic activity. Case-control studies, meta-analysis and systemic reviews covering CYP2D6 polymorphism and PD risk have demonstrated that poor metabolizer phenotype possesses a considerable genetic susceptibility. Besides, ultra-rapid metabolizer offers protection against the risk in some populations while lack of positive or inverse association is also reported in other inhabitants. CYP2D6 polymorphisms resulting into deviant protein products with differing catalytic activity could lead to inter-individual variations, which could be explained to certain extent on the basis of sample size, life style factors, food habits, ethnicity and tools used for statistical analysis across various studies. Current article describes the role played by polymorphic CYP2D6 in the metabolism of anti-PD drugs/Parkinsonian toxins and how polymorphisms determine PD risk or protection. Moreover, CYP2D6 orthologs and their roles in rodent models of Parkinsonism have also been mentioned. Finally, a perspective on inconsistency in the findings and futuristic relevance of CYP2D6 polymorphisms in disease diagnosis and treatment has also been highlighted.

Cypermethrin Activates Autophagosome Formation Albeit Inhibits Autophagy Owing to Poor Lysosome Quality: Relevance to Parkinson's Disease

Parkinson's disease (PD) is the second most familiar, progressive and movement-related neurodegenerative disorder after Alzheimer disease. This study aimed to decipher the role of autophagy in cypermethrin-induced Parkinsonism, an animal model of PD. Indicators of autophagy [expression of beclin 1, autophagy-related protein 12 (Atg 12), unc-51 like autophagy activating kinase 1 (Ulk 1), p62 and lysosome-associated membrane protein 2 (LAMP 2) and conversion of microtubule-associated protein 1A/1B-light chain 3 (LC3) I to II], signalling cascade [phosphorylated (p) 5' adenosine monophosphate-activated protein kinase (p-AMPK), sirtuin 1 (Sirt 1), phosphorylated-mammalian target of rapamycin (p-mTOR), tuberous sclerosis complex 2 (TSC 2), p₃₁₇Ulk 1 and p₇₅₇Ulk 1 levels] and lysosome morphology were assessed in control and cypermethrin-treated rat model of PD. Autophagy markers were also measured in cypermethrin-treated neuroblastoma cells in the presence of 3-methyl adenine, a phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) class III inhibitor; vinblastine, an autophagosome elongation inhibitor; bafilomycin A1, an autophagolysosome and lysosome fusion/abnormal acidification inhibitor or torin 1, a mechanistic target of rapamycin inhibitor. Cypermethrin reduced LAMP 2 and increased p-AMPK and Sirt 1 without causing any change in other signalling proteins. 3-Methyl adenine did not change LC3 conversion; vinblastine and bafilomycin A1 decreased LAMP 2 expression in controls. While cypermethrin increased LC3 conversion in the presence of 3-methyl adenine, LAMP 2 reduction was more pronounced in vinblastine and bafilomycin A1-treated cells. Torin 1 normalized the expression of LAMP 2 without any change in other autophagy markers. Results demonstrate that albeit cypermethrin activates autophagosome formation, it reduces LAMP 2 expression and lysosome quality leading to autophagy inhibition.

Neuro-Protective Effects of Resveratrol on Carbon Monoxide-Induced Toxicity in Male Rats

Acute carbon monoxide (CO) poisoning causes neurotoxicity through induction of necrosis, apoptosis, lipid peroxidation and oxidative stress. Resveratrol (RES) is a natural polyphenolic phytoalexin that exhibits neuroprotective effects in ischemia/reperfusion due to its anti-apoptotic, anti-necrotic and strong anti-oxidant properties as well as its ability to activate pro-survival pathways. In this study, rats were exposed to CO 3000 ppm for 1 h. Immediately after poisoning and on the next four consecutive days, RES (1, 5 and 10 mg/kg) was administered intraperitoneally. On the fifth day, animals' brains were excised, and necrosis, lipid peroxidation level and the level of Akt, BAX and BCL2 expression were evaluated. The results showed that RES 10 mg/kg significantly reduced lipid peroxidation, but RES 1 and 5 mg/kg had no significant effect on this parameter. Furthermore, RES 5 and 10 mg/kg significantly increased Akt expression level, while BAX/BCL2 ratio was reduced by RES 1, 5 and 10 mg/kg. Moreover, RES reduced necrotic foci in the brain, but the best results were seen following treatment with RES 10 mg/kg. In summary, RES showed neuroprotective effect in CO-poisoned rats as it decreased necrosis and BAX/BCL2 ratio and increased Akt expression levels. Copyright © 2017 John Wiley & Sons, Ltd.

Carnosic acid protects non-alcoholic fatty liver-induced dopaminergic neuron injury in rats

Non-alcoholic fatty liver disease (NAFLD) has been reported to induce cognitive impairments of hippocampus and may influence central nervous system. In the present study, we investigated whether carnosic acid (CA) ameliorates dopaminergic neuron injury in a rat model of NAFLD. In order to induce NAFLD, rats were fed with high-fat diet (HFD) for 10 weeks. We found that continued CA administration reduced lipid accumulation marked by decreases in alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglyceride (TG), total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels, and an increase in high-density lipoprotein cholesterol (HDL-C) level in the serum. H&E staining revealed that feeding CA reduced lipid droplets accumulation, and alleviated oxidative stress by increasing in superoxide dismutase (SOD) level and decreasing in malondialdehyde (MDA) level in the liver. In addition, by measuring several parameters of gait analysis, we demonstrated that CA treatment ameliorated behavioral impairments, as evidenced by decreased duration and maximum variation, accompanied by increased average speed and cadence. Furthermore, CA treated-animals displayed an increase in the contents of dopamine (DA) and its metabolites 3,4-dihydroxyphenylacelic acid (DOPAC) and elevated the expressions of tyrosine hydroxylase (TH)-positive neurons in the substantia nigra (SN) as well as the TH protein in the striatum. Together, these findings suggest that CA may be an effective agent in protecting rats from NAFLD-induced dopaminergic neuron injury.

Therapeutic potential of autophagy-enhancing agents in Parkinson's disease

Converging evidence from genetic, pathological and experimental studies have increasingly suggested an important role for autophagy impairment in Parkinson’s Disease (PD). Genetic studies have identified mutations in genes encoding for components of the autophagy-lysosomal pathway (ALP), including glucosidase beta acid 1 (GBA1), that are associated with increased risk for developing PD. Observations in PD brain tissue suggest an aberrant regulation of autophagy associated with the aggregation of α-synuclein (α-syn). As autophagy is one of the main systems involved in the proteolytic degradation of α-syn, pharmacological enhancement of autophagy may be an attractive strategy to combat α-syn aggregation in PD. Here, we review the potential of autophagy enhancement as disease-modifying therapy in PD based on preclinical evidence. In particular, we provide an overview of the molecular regulation of autophagy and targets for pharmacological modulation within the ALP. In experimental models, beneficial effects on multiple pathological processes involved in PD, including α-syn aggregation, cell death, oxidative stress and mitochondrial dysfunction, have been demonstrated using the autophagy enhancers rapamycin and lithium. However, selectivity of these agents is limited, while upstream ALP signaling proteins are involved in many other pathways than autophagy. Broad stimulation of autophagy may therefore cause a wide spectrum of dose-dependent side-effects, suggesting that its clinical applicability is limited. However, recently developed agents selectively targeting core ALP components, including Transcription Factor EB (TFEB), lysosomes, GCase as well as chaperone-mediated autophagy regulators, exert more specific effects on molecular pathogenetic processes causing PD. To conclude, the targeted manipulation of downstream ALP components, rather than broad autophagy stimulation, may be an attractive strategy for the development of novel pharmacological therapies in PD. Further characterization of dysfunctional autophagy in different stages and molecular subtypes of PD in combination with the clinical translation of downstream autophagy regulation offers exciting new avenues for future drug development.

Coherent and Contradictory Facts, Feats and Fictions Associated with Metal Accumulation in Parkinson's Disease: Epicenter or Outcome, Yet a Demigod Question

Unwarranted exposure due to liberal use of metals for maintaining the lavish life and to achieve the food demand for escalating population along with an incredible boost in the average human life span owing to orchestrated progress in rejuvenation therapy have gradually increased the occurrence of Parkinson's disease (PD). Etiology is albeit elusive; association of PD with metal accumulation has never been overlooked due to noteworthy similitude between metal-exposure symptoms and a few cardinal features of disease. Even though metals are entailed in the vital functions, a hysterical shift, primarily augmentation, escorts the stern nigrostriatal dopaminergic neurodegeneration. An increase in the passage of metals through the blood brain barrier and impaired metabolic activity and elimination system could lead to metal accumulation in the brain, which eventually makes dopaminergic neurons quite susceptible. In the present article, an update on implication of metal accumulation in PD/Parkinsonism has been provided. Moreover, encouraging and paradoxical facts and fictions associated with metal accumulation in PD/Parkinsonism have also been compiled. Systematic literature survey of PD is performed to describe updated information if metal accumulation is an epicenter or merely an outcome. Finally, a perspective on the association of metal accumulation with pesticide-induced Parkinsonism has been explained to unveil the likely impact of the former in the latter.

Neuronal Nitric Oxide Synthase Negatively Regulates Zinc-Induced Nigrostriatal Dopaminergic Neurodegeneration

The study aimed to investigate the role of NO and neuronal NO synthase (nNOS) in Zn-induced neurodegeneration. Animals were treated with zinc sulfate (20 mg/kg), twice a week, for 2-12 weeks along with control. In a few sets, animals were also treated with/without a NO donor, sodium nitroprusside (SNP), or S-nitroso-N-acetyl penicillamine (SNAP) for 12 weeks. Moreover, human neuroblastoma (SH-SY-5Y) cells were also employed to investigate the role of nNOS in Zn-induced toxicity in in vitro in the presence/absence of nNOS inhibitor, 7-nitroindazole (7-NI). Zn caused time-dependent reduction in nitrite content and total/nNOS activity/expression. SNP/SNAP discernibly alleviated Zn-induced neurobehavioral impairments, dopaminergic neurodegeneration, tyrosine hydroxylase (TH) expression, and striatal dopamine depletion. NO donors also salvage from Zn-induced increase in lipid peroxidation (LPO), mitochondrial cytochrome c release, and caspase-3 activation. While Zn elevated LPO content, it attenuated nitrite content, nNOS activity, and glutathione level along with the expression of TH and nNOS in SH-SY-5Y cells. 7-NI further augmented Zn-induced changes in the cell viability, oxidative stress, and expression of TH and nNOS. The results obtained thus demonstrate that Zn inhibits nNOS that partially contributes to an increase in oxidative stress, which subsequently leads to the nigrostriatal dopaminergic neurodegeneration.

Plant-Derived Natural Products for Parkinson's Disease Therapy

Plant-derived natural products have made their own niche in the treatment of neurological diseases since time immemorial. Parkinson's disease (PD), the second most prevalent neurodegenerative disorder, has no cure and the treatment available currently is symptomatic. This chapter thoughtfully and objectively assesses the scientific basis that supports the increasing use of these plant-derived natural products for the treatment of this chronic and progressive disorder. Proper considerations are made on the chemical nature, sources, preclinical tests and their validity, and mechanisms of behavioural or biochemical recovery observed following treatment with various plants derived natural products relevant to PD therapy. The scientific basis underlying the neuroprotective effect of 6 Ayurvedic herbs/formulations, 12 Chinese medicinal herbs/formulations, 33 other plants, and 5 plant-derived molecules have been judiciously examined emphasizing behavioral, cellular, or biochemical aspects of neuroprotection observed in the cellular or animal models of the disease. The molecular mechanisms triggered by these natural products to promote cell survivability and to reduce the risk of cellular degeneration have also been brought to light in this study. The study helped to reveal certain limitations in the scenario: lack of preclinical studies in all cases barring two; heavy dependence on in vitro test systems; singular animal or cellular model to establish any therapeutic potential of drugs. This strongly warrants further studies so as to reproduce and confirm these reported effects. However, the current literature offers scientific credence to traditionally used plant-derived natural products for the treatment of PD.