Molecular pathogenesis of Parkinson's disease

Ubiquitin Carboxyl-Terminal Hydrolase L1 and Its Role in Parkinson's Disease

Ubiquitin carboxyl-terminal hydrolase L1 (UCHL1), also known as Parkinson's disease protein 5, is a highly expressed protein in the brain. It plays an important role in the ubiquitin-proteasome system (UPS), where it acts as a deubiquitinase (DUB) enzyme. Being the smallest member of the UCH family of DUBs, it catalyzes the reaction of ubiquitin precursor processing and the cleavage of ubiquitinated protein remnants, thus maintaining the level of ubiquitin monomers in the brain cells. UCHL1 mutants, containing amino acid substitutions, influence catalytic activity and its aggregability. Some of them protect cells and transgenic mice in toxin-induced Parkinson's disease (PD) models. Studies of putative protein partners of UCHL1 revealed about sixty individual proteins located in all major compartments of the cell: nucleus, cytoplasm, endoplasmic reticulum, plasma membrane, mitochondria, and peroxisomes. These include proteins related to the development of PD, such as alpha-synuclein, amyloid-beta precursor protein, ubiquitin-protein ligase parkin, and heat shock proteins. In the context of the catalytic paradigm, the importance of these interactions is not clear. However, there is increasing understanding that UCHL1 exhibits various effects in a catalytically independent manner through protein-protein interactions. Since this protein represents up to 5% of the soluble protein in the brain, PD-related changes in its structure will have profound effects on the proteomes/interactomes in which it is involved. Growing evidence is accumulating that the role of UCHL1 in PD is obviously determined by a balance of canonic catalytic activity and numerous activity-independent protein-protein interactions, which still need better characterization.

Effect of Apigenin on Neurodegenerative Diseases

Neurodegenerative diseases (NDDs), such as Alzheimer's and Parkinson's, are the most frequent age-related illnesses affecting millions worldwide. No effective medication for NDDs is known to date and current disease management approaches include neuroprotection strategies with the hope of maintaining and improving the function of neurons. Such strategies will not provide a cure on their own but are likely to delay disease progression by reducing the production of neurotoxic chemicals such as reactive oxygen species (ROS) and related inflammatory chemicals. Natural compounds such as flavonoids that provide neuroprotection via numerous mechanisms have attracted much attention in recent years. This review discusses evidence from different research models and clinical trials on the therapeutic potential of one promising flavonoid, apigenin, and how it can be helpful for NDDs in the future prospects. We have also discussed its chemistry, mechanism of action, and possible benefits in various examples of NDDs.

Application of OpenArray Technology to Assess Changes in the Expression of Functionally Significant Genes in the Substantia Nigra of Mice in a Model of Parkinson's Disease

Studying the molecular mechanisms of the pathogenesis of Parkinson's disease (PD) is critical to improve PD treatment. We used OpenArray technology to assess gene expression in the substantia nigra (SN) cells of mice in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD and in controls. Among the 11 housekeeping genes tested, Rps27a was taken as the reference gene due to its most stable expression in normal and experimental conditions. From 101 genes encoding functionally significant proteins of nigrostriatal dopaminergic neurons, 57 highly expressed genes were selected to assess their expressions in the PD model and in the controls. The expressions of Th, Ddc, Maoa, Comt, Slc6a3, Slc18a2, Drd2, and Nr4a2 decreased in the experiment compared to the control, indicating decreases in the synthesis, degradation, and transport of dopamine and the impaired autoregulation of dopaminergic neurons. The expressions of Tubb3, Map2, Syn1, Syt1, Rab7, Sod1, Cib1, Gpx1, Psmd4, Ubb, Usp47, and Ctsb genes were also decreased in the MPTP-treated mice, indicating impairments of axonal and vesicular transport and abnormal functioning of the antioxidant and ubiquitin-proteasome systems in the SN. The detected decreases in the expressions of Snca, Nsf, Dnm1l, and Keap1 may serve to reduce pathological protein aggregation, increase dopamine release in the striatum, prevent mitophagy, and restore the redox status of SN cells.

HtrA2 regulates α-Synuclein-mediated mitochondrial reactive oxygen species production in the mitochondria of microglia

Aggregation and misfolding of α-Synuclein (α-Syn), a causative agent for Parkinson's disease (PD), and oxidative stress are tightly implicated in the pathogenesis of PD. Although more than 20 genes including HtrA2 have been identified as causative genes for PD, the molecular mechanisms underlying the pathophysiological functions between HtrA2 and α-Syn in the pathogenesis of PD remain unclear. This study shows that HtrA2 serine protease selectively recognizes and interacts with the NAC region of α-Syn. Interestingly, we found that HtrA2 causes proteolysis of α-Syn to prevent mitochondrial accumulation of α-Syn, thereby inhibiting the production of reactive oxygen species (ROS) in the mitochondria. We have further demonstrated that HtrA2 knockdown promotes α-Syn-mediated mitochondrial ROS production, thereby activating microglial cells. This study is the first to demonstrate that the HtrA2/α-Syn cellular partner may play a crucial role in the pathogenesis of PD and provide new insights into the pathological processes and effective therapeutic strategies for PD.

The Polyunsaturated Fatty Acid EPA, but Not DHA, Enhances Neurotrophic Factor Expression through Epigenetic Mechanisms and Protects against Parkinsonian Neuronal Cell Death

ω-3 Polyunsaturated fatty acids (PUFAs) have been found to exert many actions, including neuroprotective effects. In this regard, the exact molecular mechanisms are not well understood. Parkinson's disease (PD) is the second most common age-related neurodegenerative disease. Emerging evidence supports the hypothesis that PD is the result of complex interactions between genetic abnormalities, environmental toxins, mitochondrial dysfunction, and other cellular processes, such as DNA methylation. In this context, BDNF (brain-derived neurotrophic factor) and GDNF (glial cell line-derived neurotrophic factor) have a pivotal role because they are both involved in neuron differentiation, survival, and synaptogenesis. In this study, we aimed to elucidate the potential role of two PUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and their effects on BDNF and GDNF expression in the SH-SY5Y cell line. Cell viability was determined using the MTT assay, and flow cytometry analysis was used to verify the level of apoptosis. Transmission electron microscopy was performed to observe the cell ultrastructure and mitochondria morphology. BDNF and GDNF protein levels and mRNA were assayed by Western blotting and RT-PCR, respectively. Finally, methylated and hydroxymethylated DNA immunoprecipitation were performed in the BDNF and GDNF promoter regions. EPA, but not DHA, is able (i) to reduce the neurotoxic effect of neurotoxin 6-hydroxydopamine (6-OHDA) in vitro, (ii) to re-establish mitochondrial function, and (iii) to increase BNDF and GDNF expression via epigenetic mechanisms.

The Role of the Thioredoxin System in Brain Diseases

The thioredoxin system, consisting of thioredoxin (Trx), thioredoxin reductase (TrxR), and NADPH, plays a fundamental role in the control of antioxidant defenses, cell proliferation, redox states, and apoptosis. Aberrations in the Trx system may lead to increased oxidative stress toxicity and neurodegenerative processes. This study reviews the role of the Trx system in the pathophysiology and treatment of Alzheimer's, Parkinson's and Huntington's diseases, brain stroke, and multiple sclerosis. Trx system plays an important role in the pathophysiology of those disorders via multiple interactions through oxidative stress, apoptotic, neuro-immune, and pro-survival pathways. Multiple aberrations in Trx and TrxR systems related to other redox systems and their multiple reciprocal relationships with the neurodegenerative, neuro-inflammatory, and neuro-oxidative pathways are here analyzed. Genetic and environmental factors (nutrition, metals, and toxins) may impact the function of the Trx system, thereby contributing to neuropsychiatric disease. Aberrations in the Trx and TrxR systems could be a promising drug target to prevent and treat neurodegenerative, neuro-inflammatory, neuro-oxidative stress processes, and related brain disorders.

MTERF3 contributes to MPP+-induced mitochondrial dysfunction in SH-SY5Y cells

Parkinson's disease (PD) is a neurodegenerative disorder causing severe social and economic burdens. The origin of PD has been usually attributed to mitochondrial dysfunction. To this end, mitochondrial transcription regulators become attractive subjects for understanding PD pathogenesis. Previously, we found that the expression of mitochondrial transcription termination factor 3 (MTERF3) was reduced in MPP+-induced mice model of PD. In the present study, we probe the function of MTERF3 and its role in MPP+-induced cellular model of PD. Initially, we observe that MTERF3 expression is also reduced in MPP+-induced cellular model of PD, which can be mainly attributed to the increase of MTERF3 degradation. Next, we examine the effect of MTERF3 knockdown and overexpression on the replication, transcription, and translation of mitochondrial DNA (mtDNA). We show that knockdown and overexpression of MTERF3 have opposite effects on mtDNA transcript level but similar effects on mtDNA expression level, in line with MTERF3's dual roles in mtDNA transcription and translation. In addition, we examine the effect of MTERF3 knockdown and overexpression on mitochondrial function with and without MPP+ treatment, and find that MTERF3 seems to play a generally protective role in MPP+-induced mitochondrial dysfunction. Together, this work suggests a regulatory role of MTERF3 in MPP+-induced cellular model of PD and may provide clues in designing novel therapeutics against PD.

Structural Insights and Development of LRRK2 Inhibitors for Parkinson’s Disease in the Last Decade

Parkinson’s disease (PD) is the second most prevalent neurodegenerative disease, characterized by the specific loss of dopaminergic neurons in the midbrain. The pathophysiology of PD is likely caused by a variety of environmental and hereditary factors. Many single-gene mutations have been linked to this disease, but a significant number of studies indicate that mutations in the gene encoding leucine-rich repeat kinase 2 (LRRK2) are a potential therapeutic target for both sporadic and familial forms of PD. Consequently, the identification of potential LRRK2 inhibitors has been the focus of drug discovery. Various investigations have been conducted in academic and industrial organizations to investigate the mechanism of LRRK2 in PD and further develop its inhibitors. This review summarizes the role of LRRK2 in PD and its structural details, especially the kinase domain. Furthermore, we reviewed in vitro and in vivo findings of selected inhibitors reported to date against wild-type and mutant versions of the LRRK2 kinase domain as well as the current trends researchers are employing in the development of LRRK2 inhibitors.

Mechanistic Insights Expatiating the Redox-Active-Metal-Mediated Neuronal Degeneration in Parkinson's Disease

Parkinson’s disease (PD) is a complicated and incapacitating neurodegenerative malady that emanates following the dopaminergic (DArgic) nerve cell deprivation in the substantia nigra pars compacta (SN-PC). The etiopathogenesis of PD is still abstruse. Howbeit, PD is hypothesized to be precipitated by an amalgamation of genetic mutations and exposure to environmental toxins. The aggregation of α-synucelin within the Lewy bodies (LBs), escalated oxidative stress (OS), autophagy-lysosome system impairment, ubiquitin-proteasome system (UPS) impairment, mitochondrial abnormality, programmed cell death, and neuroinflammation are regarded as imperative events that actively participate in PD pathogenesis. The central nervous system (CNS) relies heavily on redox-active metals, particularly iron (Fe) and copper (Cu), in order to modulate pivotal operations, for instance, myelin generation, synthesis of neurotransmitters, synaptic signaling, and conveyance of oxygen (O₂). The duo, namely, Fe and Cu, following their inordinate exposure, are viable of permeating across the blood–brain barrier (BBB) and moving inside the brain, thereby culminating in the escalated OS (through a reactive oxygen species (ROS)-reliant pathway), α-synuclein aggregation within the LBs, and lipid peroxidation, which consequently results in the destruction of DArgic nerve cells and facilitates PD emanation. This review delineates the metabolism of Fe and Cu in the CNS, their role and disrupted balance in PD. An in-depth investigation was carried out by utilizing the existing publications obtained from prestigious medical databases employing particular keywords mentioned in the current paper. Moreover, we also focus on decoding the role of metal complexes and chelators in PD treatment. Conclusively, metal chelators hold the aptitude to elicit the scavenging of mobile/fluctuating metal ions, which in turn culminates in the suppression of ROS generation, and thereby prelude the evolution of PD.

Network metrics, structural dynamics and density functional theory calculations identified a novel Ursodeoxycholic Acid derivative against therapeutic target Parkin for Parkinson's disease

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GIN analysis revealed PARK2, LRRK2, PARK7, PINK1 and SNCA as hub-genes.

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Topologically favoured Parkin was considered as a therapeutic target.

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ADMET screening identified a novel UDCA derivative as potential lead candidate.

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Chemical reactivity and ligand stability were analysed through DFT simulation.

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Docking and MDS established novel lead as potential Parkin inhibitor.

Parkinson's disease (PD) has been designated as one of the priority neurodegenerative disorders worldwide. Although diagnostic biomarkers have been identified, early onset detection and targeted therapy are still limited. An integrated systems and structural biology approach were adopted to identify therapeutic targets for PD. From a set of 49 PD associated genes, a densely connected interactome was constructed. Based on centrality indices, degree of interaction and functional enrichments, LRRK2, PARK2, PARK7, PINK1 and SNCA were identified as the hub-genes. PARK2 (Parkin) was finalized as a potent theranostic candidate marker due to its strong association (score > 0.99) with α-synuclein (SNCA), which directly regulates PD progression. Besides, modeling and validation of Parkin structure, an extensive virtual-screening revealed small (commercially available) inhibitors against Parkin. Molecule-258 (ZINC5022267) was selected as a potent candidate based on pharmacokinetic profiles, Density Functional Theory (DFT) energy calculations (ΔE = 6.93 eV) and high binding affinity (Binding energy = -6.57 ± 0.1 kcal/mol; Inhibition constant = 15.35 µM) against Parkin. Molecular dynamics simulation of protein-inhibitor complexes further strengthened the therapeutic propositions with stable trajectories (low structural fluctuations), hydrogen bonding patterns and interactive energies (>0kJ/mol). Our study encourages experimental validations of the novel drug candidate to prevent the auto-inhibition of Parkin mediated ubiquitination in PD.

The effect of URB597, exercise or their combination on the performance of 6-OHDA mouse model of Parkinson disease in the elevated plus maze, tail suspension test and step-down task

Parkinson disease (PD) is a progressive neurodegenerative disorder that is often accompanied by motor and psychiatric symptoms. Various approaches have been proposed for the treatment of PD. Here, we investigated the effect of a low dose of fatty acid amide hydrolase inhibitor URB597 (as an enhancer of endocannabinoid anandamide levels), exercise or their combination on some behavior alterations in PD mice lesioned by 6-hydroxydopamine (6-OHDA). The impact of swimming exercise (5×/week for 4 weeks) and URB597 (0.1 mg/kg, 2×/week for 4 weeks) on the anxiety-related behavior (elevated plus maze; EPM), depression-related behavior (tail suspension test; TST), and passive avoidance memory (step-down task) was examined in the sham and male NMRI mouse of PD model. The results show that URB597 prevented memory deficits and elicited antidepressant- and anxiolytic-like effects but did not affect hypolocomotion in the PD mice. However, URB597 did not have a significant effect on the performance of the sham mice in the performed tests. Moreover, swimming training abolished depressive- and anxiogenic-like behaviors and increased locomotion without affecting memory deficits in the PD mice. Meanwhile, swimming decreased immobility time and increased locomotion in the sham mice. Furthermore, URB597 in association with swimming training prevented all deficits induced in the PD mice, while this combination impaired memory and produced the positive effects on depression- and anxiety-related behaviors and locomotion of the sham mice. It is concluded that although URB597 or exercise alone had positive effects on most behavioral tests, their combination improved all parameters in the PD mice.

Advances of Antisense Oligonucleotide Technology in the Treatment of Hereditary Neurodegenerative Diseases

Antisense nucleic acids are single-stranded oligonucleotides that have been specially chemically modified, which can bind to RNA expressed by target genes through base complementary pairing and affect protein synthesis at the level of posttranscriptional processing or protein translation. In recent years, the application of antisense nucleic acid technology in the treatment of neuromuscular diseases has made remarkable progress. In 2016, the US FDA approved two antisense nucleic acid drugs for the treatment of Duchenne muscular dystrophy (DMD) and spinal muscular atrophy (SMA), and the development to treat other neurodegenerative diseases has also entered the clinical stage. Therefore, ASO represents a treatment with great potential. The article will summarize ASO therapies in terms of mechanism of action, chemical modification, and administration methods and analyze their role in several common neurodegenerative diseases, such as SMA, DMD, and amyotrophic lateral sclerosis (ALS). This article systematically summarizes the great potential of antisense nucleic acid technology in the treatment of hereditary neurodegenerative diseases.

Alterations of Nigral Dopamine Levels in Parkinson's Disease after Environmental Enrichment and PACAP Treatment in Aging Rats

The neuroprotective effects of environmental enrichment and PACAP (pituitary adenylate cyclase-activating polypeptide) are well-described in Parkinson’s disease. The aim of our study is to investigate the beneficial effects of these factors in aging parkinsonian rats. Newborn Wistar rats were divided into standard and enriched groups according to their environmental conditions. Standard animals were raised under regular conditions. During the first five postnatal weeks, enriched pups were placed in larger cages with different objects. Aging animals received (1) saline, (2) 6-hydroxidopamine (6-OHDA), or (3) 6-OHDA + PACAP injections into the left substantia nigra (s.n.). On the seventh postoperative day, the left and right s.n. were collected. The s.n. of young and aging unoperated animals were also examined in our experiment. We determined the dopamine (DA) levels by the HPLC-MS technique, while the sandwich ELISA method was used to measure the Parkinson disease protein 7 (PARK7) protein levels. In healthy animals, we found an age-related decrease of DA levels. In aging parkinsonian-enriched rats, the operation did not result in a significant DA loss. PACAP treatment could prevent the DA loss in both the standard and enriched groups. All injured PACAP-treated rats showed remarkably higher protective PARK7 levels. The protective effect of PACAP correlated with the increase of the DA and PARK7 levels.

A role for glia maturation factor dependent activation of mast cells and microglia in MPTP induced dopamine loss and behavioural deficits in mice

The molecular mechanism mediating degeneration of nigrostriatal dopaminergic neurons in Parkinson's disease (PD) is not yet fully understood. Previously, we have shown the contribution of glia maturation factor (GMF), a proinflammatory protein in dopaminergic neurodegeneration mediated by activation of mast cells (MCs). In this study, methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced nigrostriatal neurodegeneration and astro-glial activations were determined by western blot and immunofluorescence techniques in wild type (WT) mice, MC-deficient (MC-KO) mice and GMF-deficient (GMF-KO) mice, with or without MC reconstitution before MPTP administration. We show that GMF-KO in the MCs reduces the synergistic effects of MC and Calpain1 (calcium-activated cysteine protease enzyme)-dependent dopaminergic neuronal loss that reduces motor behavioral impairments in MPTP-treated mouse. Administration of MPTP increase in calpain-mediated proteolysis in nigral dopaminergic neurons further resulting in motor decline in mice. We found that MPTP administered WT mice exhibits oxidative stress due to significant increases in the levels of malondialdehyde, superoxide dismutase and reduction in the levels of reduced glutathione and glutathione peroxidase activity as compared with both MC-KO and GMF-KO mice. The number of TH-positive neurons in the ventral tegmental area, substantia nigra and the fibers in the striatum were significantly reduced while granulocyte macrophage colony-stimulating factor (GM-CSF), MC-Tryptase, GFAP, IBA1, Calpain1 and intracellular adhesion molecule 1 expression were significantly increased in WT mice. Similarly, tyrosine hydroxylase, dopamine transporters and vesicular monoamine transporters 2 proteins expression were significantly reduced in the SN of MPTP treated WT mice. The motor behavior as analyzed by rotarod and hang test was significantly reduced in WT mice as compared with both the MC-KO and GMF-KO mice. We conclude that GMF-dependent MC activation enhances the detrimental effect of astro-glial activation-mediated oxidative stress and neuroinflammation in the midbrain, and its inhibition may slowdown the progression of PD.

A Role for SERCA Pumps in the Neurobiology of Neuropsychiatric and Neurodegenerative Disorders

Calcium (Ca²⁺) is a fundamental regulator of cell fate and intracellular Ca²⁺ homeostasis is crucial for proper function of the nerve cells. Given the complexity of neurons, a constellation of mechanisms finely tunes the intracellular Ca²⁺ signaling. We are focusing on the sarco/endoplasmic reticulum (SR/ER) calcium (Ca²⁺)-ATPase (SERCA) pump, an integral ER protein. SERCA's well established role is to preserve low cytosolic Ca²⁺ levels ([Ca²⁺]_cyt), by pumping free Ca²⁺ ions into the ER lumen, utilizing ATP hydrolysis. The SERCA pumps are encoded by three distinct genes, SERCA1-3, resulting in 12 known protein isoforms, with tissue-dependent expression patterns. Despite the well-established structure and function of the SERCA pumps, their role in the central nervous system is not clear yet. Interestingly, SERCA-mediated Ca²⁺ dyshomeostasis has been associated with neuropathological conditions, such as bipolar disorder, schizophrenia, Parkinson's disease and Alzheimer's disease. We summarize here current evidence suggesting a role for SERCA in the neurobiology of neuropsychiatric and neurodegenerative disorders, thus highlighting the importance of this pump in brain physiology and pathophysiology.

The Neuroprotective Effect of Doxycycline on Neurodegenerative Diseases

Neurodegenerative diseases (NDs) are a group of chronic, progressive disorders characterized by the gradual loss of neurons that affect specific regions of the brain, which leads to deficits in specific functions (e.g., memory, movement, cognition). The mechanism that drives chronic progression of NDs remains elusive. Among the proposed underlying pathophysiological mechanisms, aggregation and accumulation of misfolded proteins and neuroinflammation have been credited to contribute to extensive neural loss. Therapeutic agents that confer neuroprotection by downregulating these shared characteristics could therefore have beneficial effects on a wide range of NDs. In this regard, a commonly used antibiotic, doxycycline (Doxy), has been shown to reduce the progression and severity of disease in different experimental models of neurodegeneration by counteracting these common features. This review will focus on the effects reported for Doxy regarding its neuroprotective properties, the "off-target" effects, thereby supporting its evaluation as a new therapeutic approach for diseases associated with a neurodegeneration.

Dopamine: Functions, Signaling, and Association with Neurological Diseases

The dopaminergic system plays important roles in neuromodulation, such as motor control, motivation, reward, cognitive function, maternal, and reproductive behaviors. Dopamine is a neurotransmitter, synthesized in both central nervous system and the periphery, that exerts its actions upon binding to G protein-coupled receptors. Dopamine receptors are widely expressed in the body and function in both the peripheral and the central nervous systems. Dopaminergic signaling pathways are crucial to the maintenance of physiological processes and an unbalanced activity may lead to dysfunctions that are related to neurodegenerative diseases. Unveiling the neurobiology and the molecular mechanisms that underlie these illnesses may contribute to the development of new therapies that could promote a better quality of life for patients worldwide. In this review, we summarize the aspects of dopamine as a catecholaminergic neurotransmitter and discuss dopamine signaling pathways elicited through dopamine receptor activation in normal brain function. Furthermore, we describe the potential involvement of these signaling pathways in evoking the onset and progression of some diseases in the nervous system, such as Parkinson's, Schizophrenia, Huntington's, Attention Deficit and Hyperactivity Disorder, and Addiction. A brief description of new dopaminergic drugs recently approved and under development treatments for these ailments is also provided.

Effect of Chlorogenic Acid Supplementation in MPTP-Intoxicated Mouse

Oxidative stress and neuroinflammation play a key role in dopaminergic (DA) neuronal degeneration, which results in the hindrance of normal ongoing biological processes in the case of Parkinson's disease. As shown in several studies, on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration, different behavioral parameters have suggested motor impairment and damage of antioxidant defence. Thus, some specific biological molecules found in medicinal plants can be used to inhibit the DA neuronal degeneration through their antioxidant and anti-inflammatory activities. With this objective, we studied chlorogenic acid (CGA), a naturally occurring polyphenolic compound, for its antioxidant and anti-inflammatory properties in MPTP-intoxicated mice. We observed significant reoccurrence of motor coordination and antioxidant defence on CGA supplementation, which has been in contrast with MPTP-injected mice. Moreover, in the case of CGA-treated mice, the enhanced expression of tyrosine hydroxylase (TH) within the nigrostriatal region has supported its beneficial effect. The activation of glial cells and oxidative stress levels were also estimated using inducible nitric oxide synthase (iNOS) and glial fibrillary acidic protein (GFAP) immunoreactivity within substantia nigra (SN) and striatum of MPTP-injected mice. Administration of CGA has prevented the neuroinflammation in SN by regulating the nuclear factor-κB expression in the MPTP-induced group. The significant release of certain pro-inflammatory mediators such as tumor necrosis factor-α and interleukin (IL)-1β has also been inhibited by CGA with the enhanced expression of anti-inflammatory cytokine IL-10. Moreover, reduced GFAP staining within the nigrostriatal region has supported the fact that CGA has significantly helped in the attenuation of astrocyte activation. Hence, our study has shown that CGA supplementation shows its therapeutic ability by reducing the oxidative stress and neuroinflammation in MPTP-intoxicated mice.

Astragaloside IV attenuates the H2O2-induced apoptosis of neuronal cells by inhibiting α-synuclein expression via the p38 MAPK pathway

An oxidative stress insult is one of the principal causes of Parkinson's disease. Astragaloside IV (AS-IV), a constituent extracted from Astragalus membranaceus, has been demonstrated to exert antioxidant effects. However, the mechanisms responsible for the antioxidant properties and neuro-protective effects of AS-IV remain unclear. In this study, we examined the protective effects of AS-IV against the apoptosis of human neuronal cells (SH-SY5Y cells) induced by hydrogen peroxide (H₂O₂). The results revealed that AS-IV pre-treatment attenuated the H₂O₂-induced loss of SH-SY5Y cells in a dose-dependent manner; AS-IV exerted significant protecitve effects by decreasing the apoptotic ratio and attenuating reactive oxygen species overproduction in H₂O₂-exposed SH-SY5Y cells. By means of immunofluorescence staining, AS-IV was found to decrease the expression of α-synuclein and to increase the expression of tyrosine hydroxylase (TH) in the cells, which had been increased and decreased, respectively by H₂O₂. As shown by western blot analysis, the protective effects of AS-IV against SH-SY5Y cell injury induced by H₂O₂ were also mediated via the downregulation of the ratio of Bax/Bcl-2. We found that the neuroprotective effects of AS-IV were associated with the inhibition of the expression of the α-synuclein via the p38 mitogen-activated protein kinase (MAPK) signalling pathway. On the whole, our results suggest that AS-IV exerts protective effects against neurodegenerative diseases by targeting α-synuclein or TH.

Electroacupuncture Promotes Recovery of Motor Function and Reduces Dopaminergic Neuron Degeneration in Rodent Models of Parkinson's Disease

Parkinson’s disease (PD) is a common neurodegenerative disease. The pathological hallmark of PD is a progressive loss of dopaminergic neurons in the substantia nigra (SN) pars compacta in the brain, ultimately resulting in severe striatal dopamine deficiency and the development of primary motor symptoms (e.g., resting tremor, bradykinesia) in PD. Acupuncture has long been used in traditional Chinese medicine to treat PD for the control of tremor and pain. Accumulating evidence has shown that using electroacupuncture (EA) as a complementary therapy ameliorates motor symptoms of PD. However, the most appropriate timing for EA intervention and its effect on dopamine neuronal protection remain unclear. Thus, this study used the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned mouse model (systemic-lesioned by intraperitoneal injection) and the 1-methyl-4-phenylpyridinium (MPP⁺)-lesioned rat model (unilateral-lesioned by intra-SN infusion) of PD, to explore the therapeutic effects and mechanisms of EA at the GB34 (Yanglingquan) and LR3 (Taichong) acupoints. We found that EA increased the latency to fall from the accelerating rotarod and improved striatal dopamine levels in the MPTP studies. In the MPP⁺ studies, EA inhibited apomorphine induced rotational behavior and locomotor activity, and demonstrated neuroprotective effects via the activation of survival pathways of Akt and brain-derived neurotrophic factor (BDNF) in the SN region. In conclusion, we observed that EA treatment reduces motor symptoms of PD and dopaminergic neurodegeneration in rodent models, whether EA is given as a pretreatment or after the initiation of disease symptoms. The results indicate that EA treatment may be an effective therapy for patients with PD.

The unintended mitochondrial uncoupling effects of the FDA-approved anti-helminth drug nitazoxanide mitigates experimental parkinsonism in mice

Mitochondria play a primary role in the pathophysiology of Parkinson's disease (PD), and small molecules that counteract the initial stages of disease may offer therapeutic benefit. In this regard, we have examined whether the off-target effects of the Food and Drug Administration (FDA)-approved anti-helminth drug nitazoxanide (NTZ) on mitochondrial respiration could possess any therapeutic potential for PD. Results indicate that MPP⁺-induced loss in oxygen consumption rate (OCR) and ATP production by mitochondria were ameliorated by NTZ in real time by virtue of its mild uncoupling effect. Pretreatment of cells with NTZ mitigated MPP⁺-induced loss in mitochondrial OCR and reactive oxygen species (ROS). Similarly, addition of NTZ to cells pretreated with MPP⁺ could reverse block in mitochondrial OCR and reactive oxygen species induced by MPP⁺ in real time. The observed effects of NTZ were found to be transient and reversible as removal of NTZ from incubation medium restored the mitochondrial respiration to that of controls. Apoptosis induced by MPP⁺ was ameliorated by NTZ in a dose-dependent manner. In vivo results demonstrated that oral administration of NTZ (50 mg/kg) in an acute MPTP mouse model of PD conferred significant protection against the loss of tyrosine hydroxylase (TH)-positive neurons of substantia nigra. Based on the above observations we believe that repurposing of NTZ for PD may offer therapeutic benefit.

P53 Dysfunction in Neurodegenerative Diseases - The Cause or Effect of Pathological Changes?

Neurodegenerative diseases are a heterogeneous, mostly age-associated group of disorders characterized by progressive neuronal loss, the most prevalent being Alzheimer disease. It is anticipated that, with continuously increasing life expectancy, these diseases will pose a serious social and health problem in the near feature. Meanwhile, however, their etiology remains largely obscure even though all possible novel clues are being thoroughly examined. In this regard, a concept has been proposed that p53, as a transcription factor controlling many vital cellular pathways including apoptosis, may contribute to neuronal death common to all neurodegenerative disorders. In this work, we review the research devoted to the possible role of p53 in the pathogenesis of these diseases. We not only describe aberrant changes in p53 level/activity observed in CNS regions affected by particular diseases but, most importantly, put special attention to the complicated reciprocal regulatory ties existing between p53 and proteins commonly regarded as pathological hallmarks of these diseases, with the ultimate goal to identify the primary element of their pathogenesis.

Interaction of misfolded proteins and mitochondria in neurodegenerative disorders

The number of the people affected by neurodegenerative disorders is growing dramatically due to the ageing of population. The major neurodegenerative diseases share some common pathological features including the involvement of mitochondria in the mechanism of pathology and misfolding and the accumulation of abnormally aggregated proteins. Neurotoxicity of aggregated β-amyloid, tau, α-synuclein and huntingtin is linked to the effects of these proteins on mitochondria. All these misfolded aggregates affect mitochondrial energy metabolism by inhibiting diverse mitochondrial complexes and limit ATP availability in neurones. β-Amyloid, tau, α-synuclein and huntingtin are shown to be involved in increased production of reactive oxygen species, which can be generated in mitochondria or can target this organelle. Most of these aggregated proteins are capable of deregulating mitochondrial calcium handling that, in combination with oxidative stress, lead to opening of the mitochondrial permeability transition pore. Despite some of the common features, aggregated β-amyloid, tau, α-synuclein and huntingtin have diverse targets in mitochondria that can partially explain neurotoxic effect of these proteins in different brain regions.

Delivery of Dual Drug Loaded Lipid Based Nanoparticles across the Blood-Brain Barrier Impart Enhanced Neuroprotection in a Rotenone Induced Mouse Model of Parkinson's Disease

Parkinson's disease (PD) is the most widespread form of dementia where there is an age related degeneration of dopaminergic neurons in the substantia nigra region of the brain. Accumulation of α-synuclein (αS) protein aggregate, mitochondrial dysfunction, oxidative stress, and neuronal cell death are the pathological hallmarks of PD. In this context, amalgamation of curcumin and piperine having profound cognitive properties, and antioxidant activity seems beneficial. However, the blood-brain barrier (BBB) is the major impediment for delivery of neurotherapeutics to the brain. The present study involves formulation of curcumin and piperine coloaded glyceryl monooleate (GMO) nanoparticles coated with various surfactants with a view to enhance the bioavailability of curcumin and penetration of both drugs to the brain tissue crossing the BBB and to enhance the anti-parkinsonism effect of both drugs in a single platform. In vitro results demonstrated augmented inhibition of αS protein into oligomers and fibrils, reduced rotenone induced toxicity, oxidative stress, and apoptosis, and activation of autophagic pathway by dual drug loaded NPs compared to native counterpart. Further, in vivo studies revealed that our formulated dual drug loaded NPs were able to cross BBB, rescued the rotenone induced motor coordination impairment, and restrained dopaminergic neuronal degeneration in a PD mouse model.

The neurotoxicity of iron, copper and cobalt in Parkinson's disease through ROS-mediated mechanisms

Parkinson's disease (PD) is the second most common neurodegenerative disease with gradual loss of dopaminergic neurons. Despite extensive research in the past decades, the etiology of PD remains elusive. Nevertheless, multiple lines of evidence suggest that oxidative stress is one of the common causes in the pathogenesis of PD. It has also been suggested that heavy metal-associated oxidative stress may be implicated in the etiology and pathogenesis of PD. Here we review the roles of redox metals, including iron, copper and cobalt, in PD. Iron is a highly reactive element and deregulation of iron homeostasis is accompanied by concomitant oxidation processes in PD. Copper is a key metal in cell division process, and it has been shown to have an important role in neurodegenerative diseases such as PD. Cobalt induces the generation of reactive oxygen species (ROS) and DNA damage in brain tissues.

Human Basic Fibroblast Growth Factor Inhibits Tau Phosphorylation via the PI3K/Akt-GSK3β Signaling Pathway in a 6-Hydroxydopamine-Induced Model of Parkinson's Disease

BACKGROUND

Basic fibroblast growth factor (bFGF) has been increasingly investigated due to its neuroprotection in neurodegenerative disorders. Because there are still no cures for any of these disorders, it is crucial to identify new therapeutic targets and screen potential drugs. The increased phosphorylation of tau at Ser396 leads to intracellular tau accumulation, which forms neurofibrillary tangles in Parkinson's disease (PD). In this study, neuroprotection by bFGF was observed, and the mechanisms related to its regulation of phosphorylated tau were investigated.

METHODS

bFGF-loaded liposome carriers were intranasally administered to rats. The neuroprotective effects of bFGF were assessed in a PD model induced by 6-hydroxydopamine (6-OHDA) in vivo and in vitro. The phosphorylation of tau was measured, and the PI3K/Akt-GSK3β signaling pathway was investigated.

RESULTS

Our study demonstrated that liposomes markedly assisted in the delivery of bFGF to the striatum and substantia nigra of rats and enhanced the neuroprotective effects of bFGF on dopaminergic neurons. bFGF treatment significantly ameliorated the behavioral deficits induced by 6-OHDA, rescued the loss of tyrosine hydroxylase-positive neurons and increased the number of Nissl bodies. bFGF reduced the phosphorylation of tau and GSK3β and increased the phosphorylation of PI3K/Akt.

CONCLUSION

Liposomes markedly assisted in the delivery of bFGF to the brain and enhanced the neuroprotective effects of bFGF by inhibiting the phosphorylation of tau. bFGF down-regulated the phosphorylation of tau by increasing the phosphorylation of GSK3β via the PI3K/Akt signaling pathway. These findings provide a new vision of bFGF as a potential therapy for PD.

Identification of Genes Associated with Smad3-dependent Renal Injury by RNA-seq-based Transcriptome Analysis

Transforming growth factor-β/Smad3 signaling plays a critical role in the process of chronic kidney disease (CKD), but targeting Smad3 systematically may cause autoimmune disease by impairing immunity. In this study, we used whole-transcriptome RNA-sequencing to identify the differential gene expression profile, gene ontology, pathways, and alternative splicing related to TGF-β/Smad3 in CKD. To explore common dysregulation of genes associated with Smad3-dependent renal injury, kidney tissues of Smad3 wild-type and knockout mice with immune (anti-glomerular basement membrane glomerulonephritis) and non-immune (obstructive nephropathy)-mediated CKD were used for RNA-sequencing analysis. Totally 1922 differentially expressed genes (DEGs) were commonly found in these CKD models. The up-regulated genes are inflammatory and immune response associated, while decreased genes are material or electron transportation and metabolism related. Only 9 common DEGs were found to be Smad3-dependent in two models, including 6 immunoglobulin genes (Ighg1, Ighg2c, Igkv12-41, Ighv14-3, Ighv5-6 and Ighg2b) and 3 metabolic genes (Ugt2b37, Slc22a19, and Mfsd2a). Our results identify transcriptomes associated with renal injury may represent a common mechanism for the pathogenesis of CKD and reveal novel Smad3 associated transcriptomes in the development of CKD.

Neuroprotective effects of Eucommia ulmoides Oliv. and its bioactive constituent work via ameliorating the ubiquitin-proteasome system

BACKGROUND

Parkinson's disease (PD) is a chronic neurodegenerative disorder characterized by a loss of dopaminergic neurons in the substantia nigra, decreased striatal dopamine levels, and consequent extrapyramidal motor dysfunction. The purpose of this study was to investigate potential in vivo protective effects of Duzhong against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), as well as the bioactive constituents against 1-methyl-4-phenylpyridinium (MPP(+)) toxicity in vitro.

METHODS

Male C57BL/6 mice were intraperitoneally administrated five consecutive injections of MPTP every 24 h at a dose of 30 mg/kg to induce an in vivo PD model. Pole and traction tests were performed in mice to evaluate motor deficits and bradykinesia after the final MPTP administration. The striatal levels of dopamine and its metabolites, 3,4-dihydroxyphenylacetic acid and homovanilic acid, were measured using a High-performance liquid chromatography-electrical conductivity detector. To further explore the bioactive constituents and protective mechanisms of Duzhong, seven compounds from Duzhong were tested on MPP(+)-treated SH-SY5Y cell lines in vitro. A proteasome enzymatic assay and Cell Counting Kit-8 were performed to examine proteasomal activity and cell viability of Duzhong-treated cells, respectively, after exposure to MPP(+) and proteasome inhibitor MG132.

RESULTS

Duzhong antagonized the loss of striatal neurotransmitters and relieved the associated anomaly in ambulatory locomotor activity in PD mice after a 3-day pre-treatment of Duzhong crude extract. The five Duzhong compounds attenuated MPP(+)-induced dysfunction of protease activity and reduced MG132-induced cytotoxicity.

CONCLUSION

Duzhong could serve as a potential candidate for PD treatment, and its mechanism involves the amelioration of the ubiquitin-proteasome system.

Evaluation of the effect of natural peptide 'Urocortin' on corticotrophin releasing factor (CRF) receptor expression in ND7/23 cells

CRF receptors are involved in the stress management of the cells and are believed to have a cytoprotective role in the body. CRF receptors have been reported to be potential drug targets for the treatment of neurodegenerative disorders. The cell line used in the study is ND7/23 (mouse neuroblastoma and rat dorsal root ganglion neuron hybridoma). The aim of the study was to confirm the expression of CRF receptors in ND7/23 cells and to determine if urocortin (Ucn) can enhance the expression of CRF receptors. ND7/23 cells were cultured in RPMI 1640 media and cells grown after the second passage were used for the experiments. RNA was extracted from the cells and amplified by RT-PCR to confirm the presence of CRF receptors. The cells were then subjected to oxidative stress by hydrogen peroxide (0.00375%) and divided into two groups i.e. control and Ucn (10-8 μM) treated. Later RNA was extracted from both group of cells and PCR was performed. Finally, densitometry analysis was conducted on the agarose gel to determine the quantity of PCR product formed. PCR experiment confirmed the expression of both CRF-R1 and CRF-R2 in the cell line, but CRF-R1 was found to be expressed more strongly. Densitometry analysis of the PCR product and calculation of the relative expression of CRF receptors indicated a higher level of expression of CRF receptors in samples treated with Ucn as compared to those that were kept untreated. The results indicate that Ucn may be useful for the management of neuro-degenerative disorders and further studies may be carried out to establish its use as a therapeutic agent.

Compromised MAPK signaling in human diseases: an update

The mitogen-activated protein kinases (MAPKs) in mammals include c-Jun NH2-terminal kinase (JNK), p38 MAPK, and extracellular signal-regulated kinase (ERK). These enzymes are serine-threonine protein kinases that regulate various cellular activities including proliferation, differentiation, apoptosis or survival, inflammation, and innate immunity. The compromised MAPK signaling pathways contribute to the pathology of diverse human diseases including cancer and neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. The JNK and p38 MAPK signaling pathways are activated by various types of cellular stress such as oxidative, genotoxic, and osmotic stress as well as by proinflammatory cytokines such as tumor necrosis factor-α and interleukin 1β. The Ras-Raf-MEK-ERK signaling pathway plays a key role in cancer development through the stimulation of cell proliferation and metastasis. The p38 MAPK pathway contributes to neuroinflammation mediated by glial cells including microglia and astrocytes, and it has also been associated with anticancer drug resistance in colon and liver cancer. We here summarize recent research on the roles of MAPK signaling pathways in human diseases, with a focus on cancer and neurodegenerative conditions.

The S-nitrosylation status of PCNA localized in cytosol impacts the apoptotic pathway in a Parkinson's disease paradigm

It is generally accepted that nitric oxide (NO) or its derivatives, reactive nitrogen species (RNS), are involved in the development of Parkinson's disease (PD). Recently, emerging evidence in the study of PD has indicated that protein S-nitrosylation triggers the signaling changes in neurons. In this study, SH-SY5Y cells treated with rotenone were used as a model of neuronal death in PD. The treated cells underwent significant apoptosis, which was accompanied by an increase in intracellular NO in a rotenone dose-dependent manner. The CyDye switch approach was employed to screen for changes in S-nitrosylated (SNO) proteins in response to the rotenone treatment. Seven proteins with increased S-nitrosylation were identified in the treated SH-SY5Y cells, which included proliferating cell nuclear antigen (PCNA). Although PCNA is generally located in the nucleus and participates in DNA replication and repair, significant PCNA was identified in the SH-SY5Y cytosol. Using immunoprecipitation and pull-down approaches, PCNA was found to interact with caspase-9; using mass spectrometry, the two cysteine residues PCNA-Cys81 and -Cys162 were identified as candidate S-nitrosylated residues. In addition, the evidence obtained from in vitro and the cell model studies indicated that the S-nitrosylation of PCNA-Cys81 affected the interaction between PCNA and caspase-9. Furthermore, the interaction of PCNA and caspase-9 partially blocked caspase-9 activation, indicating that the S-nitrosylation of cytosolic PCNA may be a mediator of the apoptotic pathway.

Protection of MPTP-induced neuroinflammation and neurodegeneration by rotigotine-loaded microspheres

AIMS

The aim of the study is to evaluate the neuroprotective effects of continuous dopaminergic stimulation (CDS) by rotigotine-loaded microspheres (RoMS) in a mouse model of MPTP-induced Parkinson's disease (PD) and to elucidate the potential mechanism underlying these effects.

MAIN METHODS

Male C57BL/6 mice were treated either intramuscularly once with RoMS or twice daily for two weeks with rotigotine, and from the 9th day, MPTP (30 mg/kg, i.p.) was injected for the last 5 days. Following treatment, Parkinsonism scores were calculated and oxidative stress-related indicators in the striatum were performed. Neuroinflammatory cytokines, such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) were detected in the striatum. Expression of apoptosis-related proteins B-cell leukemia/lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (BAX) was measured in the striatum by Western blot. Nigral tyrosine hydroxylase (TH)-positive neurons and microglial cell markers, i.e., ionized calcium binding adaptor molecule-1 (Iba-1) and neuronal synaptosomes, were quantified to assess the neuroprotective efficacy of RoMS.

KEY FINDINGS

The administration of rotigotine significantly improved the Parkinsonism score, protected dopaminergic neurons with antioxidants, reduced microglial cell activation and the release of neuroinflammatory cytokines, and balanced the expression of Bcl-2 and Bax in MPTP-treated mice. Interestingly, the neuroprotective properties of rotigotine were remarkably amplified by CDS treatment with RoMS.

SIGNIFICANCE

These results suggest that CDS therapy can play a neuroprotective role in an MPTP mouse model. Neuroprotective disease-modifying therapy may have the potential benefits of early treatment by normalizing compensatory mechanisms and may also help to delay dyskinesia in the later stages of PD.

Depression in Parkinson's disease

Depression is a frequent comorbid disorder of Parkinson's disease; however, little is known about its pathomechanisms. Although depression is an important factor negatively affecting the quality of life of parkinsonian patients, it often remains undiagnosed and therefore untreated. Furthermore, antidepressant therapy is problematic because of the need to combine antidepressant drugs with antiparkinsonian treatments. The present paper gives an overview of characteristic features of Parkinson's disease-associated depression, experimental studies on its animal models, potential mechanisms involved in its occurrence and possible strategies for treatment.

The possible mechanism of Parkinson's disease progressive damage and the preventive effect of GM1 in the rat model induced by 6-hydroxydopamine

The progressive pathogenesis and prevention of Parkinson's disease (PD) remains unknown at present. Therefore, the present study aimed to investigate the possible progressive pathogenesis and prevention of PD. Our study investigated the content of glutamate, mitochondria calcium, calmodulin, malonaldehyde and trace elements in striatum, cerebral cortex and hippocampus tissues; and the expression of bcl-2, bax and neuronal nitric oxide synthase (nNOS) in substantia nigra and striatum; and the change of apomorphine induced rotation behavior; and the treatmental effect of monosialotetrahexosylganglioside (GM1) intraperitoneal administration for 14 days in a PD rat model induced by 6-hydroxydopamine. The results revealed that the content of glutamate significantly decreased, and that of mitochondria calcium, calmodulin, malonaldehyde and ferrum significantly increased in striatum, cerebral cortex and hippocampus tissues; the content of magnesium significantly decreased, and that of cuprum and zinc significantly increased in cerebral cortex; the expression of bcl-2 significantly decreased, and that of bax and nNOS significantly increased in substantia nigra and striatum in PD rat. GM1 can partially improve the apomorphine induced rotation behavior and changes of glutamate, mitochondria calcium, calmodulin content in striatum of PD rat. Data suggested that dysfunction of excitatory amino acids neurotransmitter, calcium homeostasis disorder, abnormal metabolism of oxygen free radicals, abnormal trace elements distribution and/or deposition and excessive apoptosis participated in the progressive process of PD, and that GM1 could partially prevent the progressive damage.

1-Benzyl-1,2,3,4-tetrahydroisoquinoline, an endogenous neurotoxic compound, disturbs the behavioral and biochemical effects of L-DOPA: in vivo and ex vivo studies in the rat

Environmental factors and endogenously produced toxins, such as 1-benzyl-1,2,3,4-tetrahydroisoquinoline (1BnTIQ), are considered to be involved in the pathogenesis of Parkinson's disease (PD). In this study, we investigated the impact of single and multiple 1BnTIQ (25 and 50 mg/kg i.p.) administration on L-DOPA-induced changes in the rate of dopamine and serotonin metabolism in the rat brain. Additionally, using in vivo microdialysis, we measured the impact of acute and multiple 1BnTIQ administrations on L-DOPA-induced dopamine release in the striatum. These data were compared with results from behavioral tests in which we measured the effect of 1BnTIQ and L-DOPA on locomotor activity. Finally, we determined the effect of the repeated administration of 1BnTIQ on the L-DOPA-induced elevation of caspase-3 activity in the hippocampus. An ex vivo neurochemical study indicated that both acute and chronic 1BnTIQ injections strongly inhibited L-DOPA-induced increases in the concentration of dopamine and all of its metabolites in dopaminergic structures. In contrast, in vivo microdialysis studies suggested that the differences in 1BnTIQ's effects are dependent on the type of treatment. A single dose of 1BnTIQ intensified the elevation of dopamine release induced by L-DOPA administration (~1,300 %; P < 0.01), while multiple administrations of 1BnTIQ significantly enhanced the basal dopamine levels while partially diminishing the effects of L-DOPA injection (~200 %; P < 0.01). Additionally, we found that chronic administration of 1BnTIQ completely blocked the L-DOPA-induced increase in caspase-3 activity in the hippocampus. These findings indicate that both acute and chronic administrations of 1BnTIQ disturbs the behavioral and biochemical effects of L-DOPA in the rat. The data presented from ex vivo and in vivo studies clearly suggest that 1BnTIQ's effects may be connected with the inhibition of DAT and/or COMT activity in the brain. Furthermore, elevated endogenous levels of 1BnTIQ may pose a serious risk in PD patients undergoing L-DOPA therapy.

Silencing of Hsp90 chaperone expression protects against 6-hydroxydopamine toxicity in PC12 cells

Parkinson's disease (PD) is the second most common age-related neurodegenerative disorder that has been shown to be associated with oxidative stress. This phenomenon occurs primarily via generation of 6-hydroxydopamine(6-OHDA) in catecholaminergic neurons leading to activation of apoptosis. The 90-kDa heat shock protein (Hsp90) functions as a chaperone in maintaining the functional stability and viability of cells under a transforming pressure. Since Hsp90 binds to inactive transcription factor heat shock factor-1 (HSF-1), inhibition of Hsp90 could activate HSF-1 and transcription of heat shock element containing genes subsequently, like Hsp70 as an anti-apoptotic factor. Our trial of silencing Hsp90 expression through transfection of Hsp90 siRNAs into neuronal PC12 cells being exposed to 6-OHDA resulted in the inhibition of pro-apoptotic factors, Bax, caspase-3, and PARP and upregulation of anti-apoptotic factor, Bcl2. In this manner,our data suggest a protective role for Hsp70 as it was observed to be induced upon Hsp90 knockdown. Furthermore, our results showed that Hsp90 silencing against 6-OHDA-induced oxidative stress may associate with upregulation of nuclear factor-erythroid 2-related factor 2. In summary, we found that silencing of Hsp90 expression leads to induction of cytoprotective pathways which can protect neurons against apoptosis in a PD model.

Selenium and selenoprotein function in brain disorders

Selenoproteins are important for normal brain function, and decreased function of selenoproteins can lead to impaired cognitive function and neurological disorders. This review examines the possible roles of selenoproteins in Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and epilepsy. Selenium deficiency is associated with cognitive decline, and selenoproteins may be helpful in preventing neurodegeneration in AD. PD is associated with impaired function of glutathione peroxidase selenoenzymes. In HD, selenium deters lipid peroxidation by increasing specific glutathione peroxidases. Selenium deficiency increases risk of seizures in epilepsy, whereas supplementation may help to alleviate seizures. Further studies on the mechanisms of selenoprotein function will increase our understanding of how selenium and selenoproteins can be used in treatment and prevention of brain disorders.

Death in the substantia nigra: a motor tragedy

It is well known that the death of dopaminergic neurons of the substantia nigra pars compacta (SNc) is the pathological hallmark of Parkinson's disease (PD), the second most common and disabling condition in the expanding elderly population. Nevertheless, the intracellular cascade of events leading to dopamine cell death is still unknown and, consequently, treatment is largely symptomatic rather than preventive. Moreover, the mechanisms whereby nigral dopaminergic neurons may degenerate still remain controversial. Hitherto, several data have shown that the earlier cellular disturbances occurring in dopaminergic neurons include oxidative stress, excitotoxicity, inflammation, mitochondrial dysfunction and altered proteolysis. These alterations, rather than killing neurons, trigger subsequent death-related molecular pathways, including elements of apoptosis. In rare incidences, PD may be inherited; this evidence has opened a new and exciting area of research, attempting to shed light on the nature of the more common idiopathic PD form. In this review, the characteristics of the SNc dopaminergic neurons and their lifecycle from birth to death are reviewed. In addition, of the mechanisms by which the aforementioned alterations cause neuronal dopaminergic death, particular emphasis will be given to the role played by inflammation, and the relevance of the possible use of anti-inflammatory drugs in the treatment of PD. Finally, new evidence of a possible de novo neurogenesis in the SNc of adult animals and in PD patients will also be examined.