The iron chelator desferrioxamine (Desferal) retards 6-hydroxydopamine-induced degeneration of nigrostriatal dopamine neurons

Driving factors of neuronal ferroptosis

Ferroptosis is an oxidative form of iron-dependent cell death characterized by the accumulation of lipid peroxides on membranes. Iron and lipids containing polyunsaturated fatty acids are essential for this process. Ferroptosis is central to several neurological diseases and underlies the importance of balanced iron and polyunsaturated fatty acid metabolism in the brain, particularly in neurons. Here, we reflect on the potential links between neuronal physiology and the accumulation of iron and peroxidated lipids, the mechanisms neurons use to protect themselves from ferroptosis, and the relationship between pathogenic protein deposition and ferroptosis in neurodegenerative disease. We propose that the unique physiology of neurons makes them especially vulnerable to ferroptosis.

The Role of Oxygen Homeostasis and the HIF-1 Factor in the Development of Neurodegeneration

Understanding the molecular underpinnings of neurodegeneration processes is a pressing challenge for medicine and neurobiology. Alzheimer's disease (AD) and Parkinson's disease (PD) represent the most prevalent forms of neurodegeneration. To date, a substantial body of experimental evidence has strongly implicated hypoxia in the pathogenesis of numerous neurological disorders, including AD, PD, and other age-related neurodegenerative conditions. Hypoxia-inducible factor (HIF) is a transcription factor that triggers a cell survival program in conditions of oxygen deprivation. The involvement of HIF-1α in neurodegenerative processes presents a complex and sometimes contradictory picture. This review aims to elucidate the current understanding of the interplay between hypoxia and the development of AD and PD, assess the involvement of HIF-1 in their pathogenesis, and summarize promising therapeutic approaches centered on modulating the activity of the HIF-1 complex.

Roles of Omega-3 Polyunsaturated Fatty Acids in Managing Cognitive Impairment in Chronic Obstructive Pulmonary Disease: A Review

Chronic obstructive pulmonary disease (COPD) contributes significantly to the death of people worldwide, especially the elderly. An essential feature of COPD is pulmonary inflammation, which results from long-term exposure to noxious substances from cigarette smoking and other environmental pollutants. Pulmonary inflammatory mediators spill over to the blood, leading to systemic inflammation, which is believed to play a significant role in the onset of a host of comorbidities associated with COPD. A substantial comorbidity of concern in COPD patients that is often overlooked in COPD management is cognitive impairment. The exact pathophysiology of cognitive impairment in COPD patients remains a mystery; however, hypoxia, oxidative stress, systemic inflammation, and cerebral manifestations of these conditions are believed to play crucial roles. Furthermore, the use of medications to treat cognitive impairment symptomatology in COPD patients has been reported to be associated with life-threatening adverse effects, hence the need for alternative medications with reduced side effects. In this Review, we aim to discuss the impact of cognitive impairment in COPD management and the potential mechanisms associated with increased risk of cognitive impairment in COPD patients. The promising roles of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) in improving cognitive deficits in COPD patients are also discussed. Interestingly, ω-3 PUFAs can potentially enhance the cognitive impairment symptomatology associated with COPD because they can modulate inflammatory processes, activate the antioxidant defence system, and promote amyloid-beta clearance from the brain. Thus, clinical studies are crucial to assess the efficacy of ω-3 PUFAs in managing cognitive impairment in COPD patients.

Lewy bodies, iron, inflammation and neuromelanin: pathological aspects underlying Parkinson's disease

Since the description of some peculiar symptoms by James Parkinson in 1817, attempts have been made to define its cause or at least to enlighten the pathology of "Parkinson's disease (PD)." The vast majority of PD subtypes and most cases of sporadic PD share Lewy bodies (LBs) as a characteristic pathological hallmark. However, the processes underlying LBs generation and its causal triggers are still unknown. ɑ-Synuclein (ɑ-syn, encoded by the SNCA gene) is a major component of LBs, and SNCA missense mutations or duplications/triplications are causal for rare hereditary forms of PD. Thus, it is imperative to study ɑ-syn protein and its pathology, including oligomerization, fibril formation, aggregation, and spreading mechanisms. Furthermore, there are synergistic effects in the underlying pathogenic mechanisms of PD, and multiple factors-contributing with different ratios-appear to be causal pathological triggers and progression factors. For example, oxidative stress, reduced antioxidative capacity, mitochondrial dysfunction, and proteasomal disturbances have each been suggested to be causal for ɑ-syn fibril formation and aggregation and to contribute to neuroinflammation and neural cell death. Aging is also a major risk factor for PD. Iron, as well as neuromelanin (NM), show age-dependent increases, and iron is significantly increased in the Parkinsonian substantia nigra (SN). Iron-induced pathological mechanisms include changes of the molecular structure of ɑ-syn. However, more recent PD research demonstrates that (i) LBs are detected not only in dopaminergic neurons and glia but in various neurotransmitter systems, (ii) sympathetic nerve fibres degenerate first, and (iii) at least in "brain-first" cases dopaminergic deficiency is evident before pathology induced by iron and NM. These recent findings support that the ɑ-syn/LBs pathology as well as iron- and NM-induced pathology in "brain-first" cases are important facts of PD pathology and via their interaction potentiate the disease process in the SN. As such, multifactorial toxic processes posted on a personal genetic risk are assumed to be causal for the neurodegenerative processes underlying PD. Differences in ratios of multiple factors and their spatiotemporal development, and the fact that common triggers of PD are hard to identify, imply the existence of several phenotypical subtypes, which is supported by arguments from both the "bottom-up/dual-hit" and "brain-first" models. Therapeutic strategies are necessary to avoid single initiation triggers leading to PD.

LUHMES Dopaminergic Neurons Are Uniquely Susceptible to Ferroptosis

Ferroptosis is a necrotic cell death caused by lipid oxidation that may be responsible for neural degeneration in Parkinson's disease. We assessed whether three neuronal cell lines are sensitive to killing by ferroptosis. Ferroptosis inducer erastin killed LUHMES neurons at sub-micromolar concentrations, whereas neuronal cells derived from SH-SY5Y cells or neural stem cells were at least 50-fold less sensitive. LUHMES differentiated neurons were likewise sensitive to killing by RSL3 or ML210, inhibitors of the glutathione peroxidase 4 enzyme (GPX4) that consumes GSH to detoxify lipid peroxides. Additional assays showed that erastin, RSL3, and ML210 increased lipid peroxide levels, and that LUHMES neurons were protected from both peroxide accumulation and cell death by ferrostatin-1. A possible role of iron was assessed by evaluating the effects of five metal chelators on cytotoxicity of erastin and RSL3. LUHMES neurons were protected from RSL3 by three of the chelators, 2,3-dimercapto-1-propanesulfonic acid (DMPS), deferoxiprone (DFX), and deferiprone (DFP). Collectively, these results demonstrate the vulnerability of LUHMES neurons to ferroptosis by chemical treatments that disrupt glutathione synthesis, lipid peroxide detoxification, or iron metabolism. The same vulnerabilities may occur in CNS neurons, which reportedly generate low levels of GSH and metallothioneins, limiting their ability to neutralize oxidative stresses and toxic metals. These results suggest a rationale and methods to search for environmental toxicants that may exploit these vulnerabilities and promote neurodegenerative diseases.

Depression in Parkinson's Disease: A Narrative Review

Parkinson's disease (PD) is a progressive neurodegenerative age-related disorder that affects the central nervous system (CNS) and is characterized by uncontrollable movements such as shaking, stiffness, and loss of balance and coordination. Depression is a common non-motor manifestation of PD, but unfortunately, depression remains unrecognized and often undertreated. The underlying pathophysiology of depression in PD is complicated, and many studies have been conducted to know the exact cause, but the question remains unanswered.

In this article, we discuss various pathophysiologies by which depression occurs in PD. The most widely accepted theories are neuroinflammation and monoamine oxidase theory. This article also explored the pharmacological treatment of depression in PD; this involves standard antidepressant therapy such as tricyclic antidepressants (TCA), serotonin-norepinephrine reuptake inhibitors (SNRI), selective serotonin reuptake inhibitors (SSRI), and monoamine oxidase inhibitors (MAO); non-pharmacological treatments such as electroconvulsive therapy (ECT), cognitive-behavioral therapy (CBT) have also been discussed. However, physicians hesitate to prescribe antidepressants to patients with PD due to concerns about harmful drug-drug interactions between antidepressants and antiparkinsonian drugs. Despite the complicated link between PD and depression, the co-administration of antidepressants and antiparkinsonian drugs is safe and beneficial when appropriately managed. However, early recognition and initiation of treatment of depression in PD reduces the longitudinal course and improves the cross-sectional picture. This review article also explored the clinical and diagnostic findings and impact on the quality of life of depression in PD.

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.

Neuroprotective Effects of Estradiol plus Lithium Chloride via Anti-Apoptosis and Neurogenesis Pathway in In Vitro and In Vivo Parkinson's Disease Models

Few pharmaceutical agents for slowing Parkinson's disease (PD) progression existed, especially for perimenopause females. The current general medications are mostly hormone replacement therapy and may have some side effects. Therefore, there is an urgent need for a novel treatment for PD. This study examined the possibility of estradiol plus lithium chloride (LiCl), one of the metal halides used as an alternative to salt. We showed that the combination of LiCl and estradiol could enhance neurogenesis proteins GAP-43 and N-myc in the human neuronal-like cells. We also further confirmed the neurogenesis activity in zebrafish. LiCl and LiCl plus estradiol could enhance 6-OHDA-induced upregulation of TGase-2b and Rho A mRNA expression. Besides, LiCl plus estradiol showed a synergic effect in anti-apoptotic activity. LiCl plus estradiol protected SH-SY5Y cells and zebrafish against 6-OHDA-induced damage on neurons than LiCl or estradiol alone groups via p-P38, p-Akt, Bcl-2, and caspase-3 cascade. The potential for developing this combination as a candidate treatment for PD is discussed.

The Association Between Parkinson's Disease and Attention-Deficit Hyperactivity Disorder

While Parkinson’s disease (PD) and attention-deficit hyperactivity disorder (ADHD) are two distinct conditions, it has been hypothesized that they share several overlapping anatomical and neurochemical changes. In order to investigate that hypothesis, this study used claims data from Taiwan’s Longitudinal Health Insurance Database 2000 to provide the significant nationwide population-based evidence of an increased risk of PD among ADHD patients, and the connection between the two conditions was not the result of other comorbidities. Moreover, this study showed that the patients with PD were 2.8 times more likely to have a prior ADHD diagnosis compared with those without a prior history of ADHD. Furthermore, an animal model of ADHD was generated by neonatally injecting rats with 6-hydroxydopamine (6-OHDA). These rats were subjected to behavior tests and the 99mTc-TRODAT-1 brain imaging at the juvenile stage. Compared to control group rats, the 6-OHDA rats showed a significantly reduced specific uptake ratio in the striatum, indicating an underlying PD-linked pathology in the brains of these ADHD phenotype-expressing rats. Overall, these results support that ADHD shares a number of anatomical and neurochemical changes with PD. As such, improved knowledge of the neurochemical mechanisms underlying ADHD could result in improved treatments for various debilitating neurological disorders, including PD.

Redox-Active Metal Ions and Amyloid-Degrading Enzymes in Alzheimer's Disease

Redox-active metal ions, Cu(I/II) and Fe(II/III), are essential biological molecules for the normal functioning of the brain, including oxidative metabolism, synaptic plasticity, myelination, and generation of neurotransmitters. Dyshomeostasis of these redox-active metal ions in the brain could cause Alzheimer’s disease (AD). Thus, regulating the levels of Cu(I/II) and Fe(II/III) is necessary for normal brain function. To control the amounts of metal ions in the brain and understand the involvement of Cu(I/II) and Fe(II/III) in the pathogenesis of AD, many chemical agents have been developed. In addition, since toxic aggregates of amyloid-β (Aβ) have been proposed as one of the major causes of the disease, the mechanism of clearing Aβ is also required to be investigated to reveal the etiology of AD clearly. Multiple metalloenzymes (e.g., neprilysin, insulin-degrading enzyme, and ADAM10) have been reported to have an important role in the degradation of Aβ in the brain. These amyloid degrading enzymes (ADE) could interact with redox-active metal ions and affect the pathogenesis of AD. In this review, we introduce and summarize the roles, distributions, and transportations of Cu(I/II) and Fe(II/III), along with previously invented chelators, and the structures and functions of ADE in the brain, as well as their interrelationships.

Parkinson's disease: Alterations in iron and redox biology as a key to unlock therapeutic strategies

A plethora of studies indicate that iron metabolism is dysregulated in Parkinson's disease (PD). The literature reveals well-documented alterations consistent with established dogma, but also intriguing paradoxical observations requiring mechanistic dissection. An important fact is the iron loading in dopaminergic neurons of the substantia nigra pars compacta (SNpc), which are the cells primarily affected in PD. Assessment of these changes reveal increased expression of proteins critical for iron uptake, namely transferrin receptor 1 and the divalent metal transporter 1 (DMT1), and decreased expression of the iron exporter, ferroportin-1 (FPN1). Consistent with this is the activation of iron regulator protein (IRP) RNA-binding activity, which is an important regulator of iron homeostasis, with its activation indicating cytosolic iron deficiency. In fact, IRPs bind to iron-responsive elements (IREs) in the 3ꞌ untranslated region (UTR) of certain mRNAs to stabilize their half-life, while binding to the 5ꞌ UTR prevents translation. Iron loading of dopaminergic neurons in PD may occur through these mechanisms, leading to increased neuronal iron and iron-mediated reactive oxygen species (ROS) generation. The "gold standard" histological marker of PD, Lewy bodies, are mainly composed of α-synuclein, the expression of which is markedly increased in PD. Of note, an atypical IRE exists in the α-synuclein 5ꞌ UTR that may explain its up-regulation by increased iron. This dysregulation could be impacted by the unique autonomous pacemaking of dopaminergic neurons of the SNpc that engages L-type Ca+2 channels, which imparts a bioenergetic energy deficit and mitochondrial redox stress. This dysfunction could then drive alterations in iron trafficking that attempt to rescue energy deficits such as the increased iron uptake to provide iron for key electron transport proteins. Considering the increased iron-loading in PD brains, therapies utilizing limited iron chelation have shown success. Greater therapeutic advancements should be possible once the exact molecular pathways of iron processing are dissected.

Inflaming the Brain with Iron

Iron accumulation and neuroinflammation are pathological conditions found in several neurodegenerative diseases, including Alzheimer's disease (AD) and Parkinson's disease (PD). Iron and inflammation are intertwined in a bidirectional relationship, where iron modifies the inflammatory phenotype of microglia and infiltrating macrophages, and in turn, these cells secrete diffusible mediators that reshape neuronal iron homeostasis and regulate iron entry into the brain. Secreted inflammatory mediators include cytokines and reactive oxygen/nitrogen species (ROS/RNS), notably hepcidin and nitric oxide (·NO). Hepcidin is a small cationic peptide with a central role in regulating systemic iron homeostasis. Also present in the cerebrospinal fluid (CSF), hepcidin can reduce iron export from neurons and decreases iron entry through the blood-brain barrier (BBB) by binding to the iron exporter ferroportin 1 (Fpn1). Likewise, ·NO selectively converts cytosolic aconitase (c-aconitase) into the iron regulatory protein 1 (IRP1), which regulates cellular iron homeostasis through its binding to iron response elements (IRE) located in the mRNAs of iron-related proteins. Nitric oxide-activated IRP1 can impair cellular iron homeostasis during neuroinflammation, triggering iron accumulation, especially in the mitochondria, leading to neuronal death. In this review, we will summarize findings that connect neuroinflammation and iron accumulation, which support their causal association in the neurodegenerative processes observed in AD and PD.

The Role of Oxidative Stress in Parkinson's Disease

Parkinson’s disease (PD) is caused by progressive neurodegeneration of dopaminergic (DAergic) neurons with abnormal accumulation of α-synuclein in substantia nigra (SN). Studies have suggested the potential involvement of dopamine, iron, calcium, mitochondria and neuroinflammation in contributing to overwhelmed oxidative stress and neurodegeneration in PD. Function studies on PD-causative mutations of SNCA, PRKN, PINK1, DJ-1, LRRK2, FBXO7 and ATP13A2 further indicate the role of oxidative stress in the pathogenesis of PD. Therefore, it is reasonable that molecules involved in oxidative stress, such as DJ-1, coenzyme Q10, uric acid, 8-hydroxy-2’-deoxyguanosin, homocysteine, retinoic acid/carotenes, vitamin E, glutathione peroxidase, superoxide dismutase, xanthine oxidase and products of lipid peroxidation, could be candidate biomarkers for PD. Applications of antioxidants to modulate oxidative stress could be a strategy in treating PD. Although a number of antioxidants, such as creatine, vitamin E, coenzyme Q10, pioglitazone, melatonin and desferrioxamine, have been tested in clinical trials, none of them have demonstrated conclusive evidence to ameliorate the neurodegeneration in PD patients. Difficulties in clinical studies may be caused by the long-standing progression of neurodegeneration, lack of biomarkers for premotor stage of PD and inadequate drug delivery across blood–brain barrier. Solutions for these challenges will be warranted for future studies with novel antioxidative treatment in PD patients.

Clioquinol improves motor and non-motor deficits in MPTP-induced monkey model of Parkinson's disease through AKT/mTOR pathway

Despite decades of research into the pathology mechanisms of Parkinson’s disease (PD), disease-modifying therapy of PD is scarce. Thus, searching for new drugs or more effective neurosurgical treatments has elicited much interest. Clioquinol (CQ) has been shown to have therapeutic benefits in rodent models of neurodegenerative disorders. However, it’s neuroprotective role and mechanisms in PD primate models and PD patients, especially in the advanced stages, are not fully understood. Furthermore, issues such as spontaneous recovery of motor function and high symptom variability in different monkeys after the same toxic protocol, has not been resolved before the present study. In this study, we designed a chronic and long-term progressive protocol to generate a stabilized PD monkey model showed with classic motor and non-motor deficits, followed by treatment analysis of CQ. We found that CQ could remarkably improve the motor and non-motor deficits, which were based on the reduction of iron content and ROS level in the SN and further improvement in pathology. Meanwhile, we also showed that ferroptosis was probably involved in the pathogenesis of PD. In addition, the study shows a positive effect of CQ on AKT/mTOR survival pathway and a blocking effect on p53 medicated cell death in vivo and in vitro.

The Effect of Sodium Metabisulphite on Apoptosis in the Experimental Model of Parkinson’s Disease

Background:

The aim of this study was to investigate the mechanisms underlying possible toxic effects of sulphite on neurodegeneration.

Methods:

Male Wistar rats were assigned to each of the four groups: Control (Control), Sulphite-treated (Sulphite), 6-hydroxydopamine (6-OHDA)-injected (6-OHDA), and sulphite-treated and 6-OHDA-injected (6-OHDA+Sulphite). Sodium metabisulphite was administered orally by gavage at a dose of 100 mg/kg/day for 45 days. Experimental PD was created stereotactically via the unilateral infusion of 6-OHDA into the medial forebrain bundle (MFB). Rotarod performances, plasma S-sulfonate levels, caspase-3 activities, Bax and Bcl-2 levels, tyrosine hydroxylase (TH) and cleaved caspase-3 double staining were investigated.

Results:

The rotarod test showed that the 6-OHDA-injected animals exhibited shorter time on the rod mile compared to the control group; however, there was no difference between 6-OHDA and 6-OHDA+Sulphite groups. Plasma levels of S-sulfonate in Sulphite and 6-OHDA+ Sulphite groups increased in contrast to their corresponding control groups. Caspase-3 enzyme activity increased in the 6-OHDA group whereas it did not in control. However, sulphite treatment did not affect these activity levels. Anti-apoptotic protein Bcl-2 concentration decreased, but the concentration of pro-apoptotic protein Bax increased in the 6-OHDA group compared to the control group. The expression of caspase-3 increased, while the number of tyrosine hydroxylase (TH)-positive neurons decreased in 6-OHDA group as compared to the control groups. However, sulphite treatment had no effect on these parameters.

Conclusion:

Sulphite is not a potentially aggravating factor for the activity of caspase-3 in a 6- OHDA-induced experimental model of Parkinson’s disease.

Intranasal deferoxamine can improve memory in healthy C57 mice, suggesting a partially non-disease-specific pathway of functional neurologic improvement

INTRODUCTION

Intranasal deferoxamine (IN DFO) has been shown to decrease memory loss and have beneficial impacts across several models of neurologic disease and injury, including rodent models of Alzheimer's and Parkinson's disease.

METHODS

In order to assess the mechanism of DFO, determine its ability to improve memory from baseline in the absence of a diseased state, and assess targeting ability of intranasal delivery, we treated healthy mice with IN DFO (2.4 mg) or intraperitoneal (IP) DFO and compared behavioral and biochemical changes with saline-treated controls. Mice were treated 5 days/week for 4 weeks and subjected to behavioral tests 30 min after dosing.

RESULTS

We found that IN DFO, but not IP DFO, significantly enhanced working memory in the radial arm water maze, suggesting that IN administration is more efficacious as a targeted delivery route to the brain. Moreover, the ability of DFO to improve memory from baseline in healthy mice suggests a non-disease-specific mechanism of memory improvement. IN DFO treatment was accompanied by decreased GSK-3β activity and increased HIF-1α activity.

CONCLUSIONS

These pathways are suspected in DFO's ability to improve memory and perhaps represent a component of the common mechanism through which DFO enacts beneficial change in models of neurologic disease and injury.

Novel Oxindole-Curcumin Hybrid Compound for Antioxidative Stress and Neuroprotection

Oxidative stress plays an important role in the pathogenesis of Parkinson's disease and other neurodegenerative disorders. The oxindole compound GIF-2165X-G1 is a hybrid molecule composed of the oxindole skeleton of the neuroprotective compound GIF-0726-r and the polyphenolic skeleton of the antioxidant curcumin. We previously reported that novel oxindole derivatives such as GIF-0726-r and GIF-2165X-G1 prevent endogenous oxidative stress-induced cell death in mouse hippocampal HT22 cells. In this study, we present a detailed investigation of the effect of GIF-2165X-G1 on endogenous oxidative stress in HT22 cells in comparison with GIF-0726-r and curcumin. GIF-2165X-G1 exhibited more potent neuroprotective activity than GIF-0726-r or curcumin and had less cytotoxicity than that observed with curcumin. Both GIF-0726-r and GIF-2165X-G1 were found to have ferrous ion chelating activity similar to that exhibited by curcumin. GIF-2165 X-G1 and curcumin induced comparable antioxidant response element transcriptional activity. Although the induction of heme oxygenase-1, an antioxidant response element-regulated gene product, was much stronger in curcumin-treated cells than in GIF-2165X-G1-treated cells, it turned out that the induction of heme oxygenase-1 is dispensable for neuroprotection. These results demonstrate that the introduction of the polyphenol skeleton of curcumin to the oxindole GIF-0726-r improves neuroprotective features. Furthermore, intrastriatal injection of GIF-2165X-G1 alleviated apomorphine-induced rotation and prevented dopaminergic neuronal loss in a 6-hydroxydopamine mouse model of Parkinson's diseases. Collectively, our novel findings indicate that the novel oxindole compound GIF-2165X-G1 serves to delay the progression of Parkinson's disease by suppressing oxidative stress.

Mobility Deficits Assessed With Mobile Technology: What Can We Learn From Brain Iron-Altered Animal Models?

Background: Recent developments in mobile technology have enabled the investigation of human movements and mobility under natural conditions, i.e., in the home environment. Iron accumulation in the basal ganglia is deleterious in Parkinson's disease (i.e., iron accumulation with lower striatal level of dopamine). The effect of iron chelation (i.e., re-deployment of iron) in Parkinson's disease patients is currently tested in a large investigator-initiated multicenter study. Conversely, restless legs syndrome (RLS) is associated with iron depletion and higher striatal level of dopamine. To determine from animal models which movement and mobility parameters might be associated with iron content modulation and the potential effect of therapeutic chelation inhuman.

Methods: We recapitulated pathophysiological aspects of the association between iron, dopamine, and neuronal dysfunction and deterioration in the basal ganglia, and systematically searched PubMed to identify original articles reporting about quantitatively assessed mobility deficits in animal models of brain iron dyshomeostasis.

Results: We found six original studies using murine and fly models fulfilling the inclusion criteria. Especially postural and trunk stability were altered in animal models with iron overload. Animal models with lowered basal ganglia iron suffered from alterations in physical activity, mobility, and sleep fragmentation.

Conclusion: From preclinical investigations in the animal model, we can deduce that possibly also in humans with iron accumulation in the basal ganglia undergoing therapeutic chelation may primarily show changes in physical activity (such as daily “motor activity”), postural and trunk stability and sleep fragmentation. These changes can readily be monitored with currently available mobile technology.

Desferrioxamine and dextromethorphan combination exhibited synergistic effect and reversed the catalepsy behaviour in 6-hydroxydopamine hydroydopamine administered rats through regulating brain glutamate levels

OBJECTIVE

To investigate the effect of desferrioxamine (DFO) and dextromethorphan (DXM) combination in animal model of Parkinson's disease (PD).

METHODS

The PD was induced in rats through intracerebroventricular administration of 6-hydroxydopamine (6-OHDA) using stereotaxic apparatus. The animals were subjected to behavioural assessments and neurobiochemicals estimation followed by immunohistochemistry staining of neuron specific enolase (NSE) in striatum.

KEY FINDINGS

Desferrioxamine and DXM combination has significantly reversed the catalepsy behaviour and elevated the antioxidant enzymes (SOD, CAT, GSH) and dopamine levels. Interestingly, the level of glutamate, nitric oxide, cytokines (IL-1β, TNF-α) and NSE expressions were found to be decreased in striatum region of 6-OHDA-administered rats. The combination of DFO and DXM has shown synergism in most of the parameters studied, when compared to per se treatment.

CONCLUSIONS

The reversal of catalepsy behaviour represents the protective effect of above combination on dopamine neurons in striatum from 6-OHDA toxicity. The mechanism of DFO and DXM combination might be attributed through attenuation of glutamate-induced excitotoxicity in neurons through ameliorating the reactive oxygen species and pro-inflammatory cytokines release. Treatment with DFO and DXM combination could control the multiple events in the pathogenesis of PD.

Monoamine oxidase inhibitors, and iron chelators in depressive illness and neurodegenerative diseases

In early 1920s, tyramine oxidase was discovered that metabolized tyramine and in 1933 Blaschko demonstrated that this enzyme also metabolized adrenaline, noradrenaline and dopamine. Zeller gave it the name monoamine oxidase (MAO) to distinguish it from the enzyme that oxidatively deaminated diamines. MAO was recognized as an enzyme of crucial interest to pharmacologists because it catalyzed the major inactivation pathway for the catecholamines (and, later, 5-hydroxytryptamine, as well). Within the few decade, the inhibitors of MAO were discovered and introduced for the treatment of depressive illness which was established clinically. However, the first clinical use exposed serious side effects, pharmacological interest in, and investigation of, MAO continued, resulting in the characterization of two forms, distinct forms, MAO-A and -B, and selective inhibitors for them. Selective inhibitors of MAO-B (selegiline, rasagiline and safinamide) have found a therapeutic role in the treatment of Parkinson's disease and reversible inhibitors of MAO-A offered antidepressant activity without the serious side effects of the earlier nonselective MAO inhibitors. Subsequent molecular pharmacological have also generated the concept of neuroprotection, reflecting the possibility of slowing, halting and maybe reversing, neurodegeneration in Parkinson's or Alzheimer's diseases. Increased levels of oxidative stress through the accumulation of iron in the Parkinsonian and Alzheimer brains has been suggested to be critical for the initiation and progress of neurodegeneration. Selective inhibition of brain MAO could contribute importantly to lowering such stress, preventing the formation of hydrogen peroxide. Interaction of Iron with hydrogen peroxide and lead to Fenton reaction and production of the most reactive radical, namely hydroxyl radical. There are complex interactions between free iron levels in brain and MAO, and cascade of neurotoxic events may have practical outcomes for depressive disorders and neurodegenerative diseases. As consequence recent novel therapeutic drugs for neurodegenerative diseases has led to the development of multi target drugs, that possess selective brain MAO A and B inhibitory moiety, iron chelating and antioxidant activities and the ability to increase brain levels of endogenous neurotrophins, such as BDNF, GDNF VEGF and erythropoietin and induce mitochondrial biogenesis.

How do we fit ferroptosis in the family of regulated cell death?

In the last few years many new cell death modalities have been described. To classify different types of cell death, the term 'regulated cell death' was introduced to discriminate it from 'accidental cell death'. Regulated cell death involves the activation of genetically encoded molecular machinery that couples the presence of some signal to cell death. These forms of cell death, like apoptosis, necroptosis and pyroptosis have important physiological roles in development, tissue repair, and immunity. Accidental cell death occurs in response to physical or chemical insults and occurs independently of molecular signalling pathways. Ferroptosis, an emerging and recently (re)discovered type of regulated cell death occurs through Fe(II)-dependent lipid peroxidation when the reduction capacity of a cell is insufficient. Ferroptosis is coined after the requirement for free ferrous iron. Here, we will consider the extent to which ferroptosis is similar to other regulated cell deaths and explore emerging ideas about the physiological role of ferroptosis.

Baicalein prevents 6-OHDA/ascorbic acid-induced calcium-dependent dopaminergic neuronal cell death

6-OHDA plus ascorbic acid (AA) has long been used to induce Parkinson’s disease in rodents, while only 6-OHDA is commonly used to induce cell damage in cellular PD models. AA was believed to act as an anti-oxidant to prevent the degradation of 6-OHDA; however, some studies suggested that AA dramatically enhanced the selectivity and toxicity of 6-OHDA. To understand the mechanisms by which 6-OHDA/AA induces cell death, we established a 6-OHDA/AA cell toxicity model in human dopaminergic neuroblastoma SH-SY5Y cells. We confirmed that the toxicity of 6-OHDA was dramatically increased in the presence of AA, and the toxicity can be prevented by a flavonoid, baicalein. Mechanistically, our research reveals that 6-OHDA/AA induces cell death mainly through the interruption of intracellular calcium homeostasis, which leads to calpain activation and mitochondrial damage. Baicalein prevents 6-OHDA/AA-induced intracellular calcium elevation as well as consequent mitochondria damage. Taken together, our study confirms that 6-OHDA/AA is a more sensitive model for inducing neuronal lesion in vitro and reveals the central role of intracellular calcium in 6-OHDA/AA-induced cell death. Our studies further show that baicalein prevents 6-OHDA/AA-induced cell death by inhibiting intracellular calcium elevation.

Intranasal deferoxamine affects memory loss, oxidation, and the insulin pathway in the streptozotocin rat model of Alzheimer's disease

Accumulation of metal and the accompanying increase in oxidative stress and inflammation plays an important role in neurodegenerative disease. Deferoxamine (DFO) is a metal chelator found to be beneficial in several animal models of neurodegenerative disease and insult including Alzheimer's disease, Parkinson's disease, stroke, and subarachnoid hemorrhage. In this study, we determine whether intranasally (IN) administered DFO is beneficial in the intracerebroventricular streptozotocin (ICV STZ) rat model of sporadic Alzheimer's disease, which is different from previous models in that it exhibits dysregulation of insulin metabolism as well as oxidative stress and inflammation. Surgical induction of the model included ICV injections of either STZ or citrate buffer (sham in rats), which were treated IN with either saline or DFO (n=10-15/group). Treatment started either before or after injection of STZ to induce the model, and continued throughout the study. IN treatment continued three times per week for three weeks before behavior tests started followed by eventual euthanasia with tissue collection. Spatial memory tests with the Morris water maze showed that STZ rats treated with IN DFO both before and after model induction had significantly shorter escape latencies. Pre-treatment with IN DFO also significantly decreased footslips on the tapered balance beam test. Brain tissue analyses showed DFO treatment decreased oxidation as measured by oxyblot and increased insulin receptor expression. These results further support the potential of IN DFO for use as a treatment for Alzheimer's disease, and show benefit in a non-amyloid/tau rodent model.

Anti-Oxidants in Parkinson's Disease Therapy: A Critical Point of View

Parkinson’s disease (PD) is a degenerative neurological syndrome, which is characterized by the preferential death of dopaminergic (DAergic) neurons in the Substantia Nigra. The pathogenesis of this disorder remains poorly understood and PD is still incurable. Current drug treatments are aimed primarily for the treatment of symptoms to improve the quality of life. Therefore, there is a need to find out new therapeutic strategies that not only provide symptomatic relief but also halt or reverse the neuronal damage hampering PD progression. Oxidative stress has been identified as one of the major contributors for the nigral loss in both sporadic and genetic forms of PD. In this review we first evaluate the current literature that links oxidative stress and mitochondrial dysfunction to PD. We then consider the results obtained through the treatment of animal models or PD patients with molecules that prevent oxidative stress or reduce mitochondrial dysfunction.

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.

Parkinson's Disease: The Mitochondria-Iron Link

Mitochondrial dysfunction, iron accumulation, and oxidative damage are conditions often found in damaged brain areas of Parkinson's disease. We propose that a causal link exists between these three events. Mitochondrial dysfunction results not only in increased reactive oxygen species production but also in decreased iron-sulfur cluster synthesis and unorthodox activation of Iron Regulatory Protein 1 (IRP1), a key regulator of cell iron homeostasis. In turn, IRP1 activation results in iron accumulation and hydroxyl radical-mediated damage. These three occurrences-mitochondrial dysfunction, iron accumulation, and oxidative damage-generate a positive feedback loop of increased iron accumulation and oxidative stress. Here, we review the evidence that points to a link between mitochondrial dysfunction and iron accumulation as early events in the development of sporadic and genetic cases of Parkinson's disease. Finally, an attempt is done to contextualize the possible relationship between mitochondria dysfunction and iron dyshomeostasis. Based on published evidence, we propose that iron chelation-by decreasing iron-associated oxidative damage and by inducing cell survival and cell-rescue pathways-is a viable therapy for retarding this cycle.

Brain Iron Metabolism Dysfunction in Parkinson's Disease

Dysfunction of iron metabolism, which includes its uptake, storage, and release, plays a key role in neurodegenerative disorders, including Parkinson's disease (PD), Alzheimer's disease, and Huntington's disease. Understanding how iron accumulates in the substantia nigra (SN) and why it specifically targets dopaminergic (DAergic) neurons is particularly warranted for PD, as this knowledge may provide new therapeutic avenues for a more targeted neurotherapeutic strategy for this disease. In this review, we begin with a brief introduction describing brain iron metabolism and its regulation. We then provide a detailed description of how iron accumulates specifically in the SN and why DAergic neurons are especially vulnerable to iron in PD. Furthermore, we focus on the possible mechanisms involved in iron-induced cell death of DAergic neurons in the SN. Finally, we present evidence in support that iron chelation represents a plausable therapeutic strategy for PD.

Deferoxamine-mediated up-regulation of HIF-1α prevents dopaminergic neuronal death via the activation of MAPK family proteins in MPTP-treated mice

Accumulating evidence suggests that an abnormal accumulation of iron in the substantia nigra (SN) is one of the defining characteristics of Parkinson's disease (PD). Accordingly, the potential neuroprotection of Fe chelators is widely acknowledged for the treatment of PD. Although desferrioxamine (DFO), an iron chelator widely used in clinical settings, has been reported to improve motor deficits and dopaminergic neuronal survival in animal models of PD, DFO has poor penetration to cross the blood-brain barrier and elicits side effects. We evaluated whether an intranasal administration of DFO improves the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced degeneration of dopaminergic neurons in the nigrostriatal axis and investigated the molecular mechanisms of intranasal DFO treatment in preventing MPTP-induced neurodegeneration. Treatment with DFO efficiently alleviated behavioral deficits, increased the survival of tyrosine hydroxylase (TH)-positive neurons, and decreased the action of astrocytes in the SN and striatum in an MPTP-induced PD mouse model. Interestingly, we found that DFO up-regulated the expression of HIF-1α protein, TH, vascular endothelial growth factor (VEGF), and growth associated protein 43 (GAP43) and down-regulated the expression of α-synuclein, divalent metal transporter with iron-responsive element (DMT1+IRE), and transferrin receptor (TFR). This was accompanied by a decrease in iron-positive cells in the SN and striatum of the DFO-treated group. We further revealed that DFO treatment significantly inhibited the MPTP-induced phosphorylation of the c-Jun N-terminal kinase (JNK) and differentially enhanced the phosphorylation of extracellular regulated protein kinases (ERK) and mitogen-activated protein kinase (MAPK)/P38 kinase. Additionally, the effects of DFO on increasing the Bcl-2/Bax ratio were further validated in vitro and in vivo. In SH-SY5Y cells, the DFO-mediated up-regulation of HIF-1α occurred via the activation of the ERK and P38MAPK signaling pathway. Collectively, the present data suggest that intranasal DFO treatment is effective in reversing MPTP-induced brain abnormalities and that HIF-1-pathway activation is a potential therapy target for the attenuation of neurodegeneration.

Regulators of mitochondrial complex I activity: A review of literature and evaluation in postmortem prefrontal cortex from patients with bipolar disorder

Phenomenologically, bipolar disorder (BD) is characterized by biphasic increases and decreases in energy. As this is a state-related phenomenon, identifying regulators responsible for this phasic dysregulation has the potential to uncover key elements in the pathophysiology of BD. Given the evidence suggesting mitochondrial complex I dysfunction in BD, we aimed to identify the main regulators of complex I in BD by reviewing the literature and using the published microarray data to examine their gene expression profiles. We also validated protein expression levels of the main complex I regulators by immunohistochemistry. Upon reviewing the literature, we found PARK-7, STAT-3, SIRT-3 and IMP-2 play an important role in regulating complex I activity. Published microarray studies however revealed no significant direction of regulation of STAT-3, SIRT-3, and IMP-2, but a trend towards downregulation of PARK-7 was observed in BD. Immunocontent of DJ-1 (PARK-7-encoded protein) were not elevated in post mortem prefrontal cortex from patients with BD. We also found a trend towards upregulation of DJ-1 expression with age. Our results suggest that DJ-1 is not significantly altered in BD subjects, however further studies are needed to examine DJ-1 expression levels in a cohort of older patients with BD.

Moderate-Intensity Physical Exercise Protects Against Experimental 6-Hydroxydopamine-Induced Hemiparkinsonism Through Nrf2-Antioxidant Response Element Pathway

INTRODUCTION

Exercise improves the motor symptoms of patients with Parkinson disease in a palliative manner. Existing evidence demonstrates that exercise induces neuroprotection based on the neurotrophic properties. We investigated the effect of exercise on mitochondrial physiology and oxidative stress in an animal model of hemiparkinsonism.

METHODS

C57BL/6 mice completed a 6-week exercise program on a treadmill. We injected 6-hydroxydopamine (6-OHDA; 4 μg/2 μl) into the midstriatum. The animals progressively developed bradykinesia and R(-)-apomorphine-induced rotations that were attenuated by exercise. Transcriptional activation of protective genes is mediated by the antioxidant response element (ARE). Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) binds to ARE. We investigated the Nrf2-ARE pathway in the striatum of animals.

RESULTS

Exercise protected 6-OHDA-induced loss of tyrosine hydroxylase immunolabeling and activated the Nrf2-ARE pathway in the nigrostriatal pathway. Exercise stimulated mitochondrial biogenesis in the striatum of animals that was more resistant to oxidant 6-OHDA and nitric oxide donor (±)-S-nitroso-N-acetylpenicillamine.

CONCLUSIONS

In mice, exercise activated Nrf2-ARE signaling in the nigrostriatal pathway that was protective against the development of hemiparkinsonism.

Targeting mitochondrial metal dyshomeostasis for the treatment of neurodegeneration

Mitochondrial impairment and metal dyshomeostasis are suggested to be associated with many neurodegenerative disorders including Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis and Friedreich's ataxia. Treatments aimed at restoring metal homeostasis are highly effective in models of these diseases, and clinical trials hold promise. However, in general, the effect of these treatments on mitochondrial metal homeostasis is unclear, and the contribution of mitochondrial metal dyshomeostasis to disease pathogenesis requires further investigation. This review describes the role of metals in mitochondria in health, how mitochondrial metals are disrupted in neurodegenerative diseases, and potential therapeutics aimed at restoring mitochondrial metal homeostasis and function.

Iron Accumulation Is Not Homogenous among Patients with Parkinson's Disease

Background. Iron is considered to lead to neurodegeneration and has been hypothesized as a possible cause of Parkinson's disease (PD). Susceptibility-weighted imaging (SWI) is a powerful tool to measure phase related iron content of brain. Methods. Twelve de novo patients with PD were recruited from the Movement Disorders Clinic, Department of Neurology, Loma Linda University. Twelve age- and sex-matched non-PD subjects were recruited from neurology clinic as controls. Using SWI, the phase related iron content was estimated from different brain regions of interest (ROIs). Results. There was a trend between increasing age and iron accumulation in the globus pallidus and putamen in all subjects. Iron accumulation was not significant in different ROIs in PD patients compared to controls after adjustment for age. Our data revealed heterogeneity of phase values in different brain ROIs among all subjects with an exaggerated trend at SN in PD patients. Conclusions. Our data suggest a nonhomogeneous pattern of iron accumulation in different brain regions among PD patients. Further studies are needed to explore whether this may correlate to the progression of PD. To our knowledge, this is the first study demonstrating the heterogeneity of iron accumulation in the brain, among patients with PD.

Clioquinol rescues Parkinsonism and dementia phenotypes of the tau knockout mouse

Iron accumulation and tau protein deposition are pathological features of Alzheimer's (AD) and Parkinson's diseases (PD). Soluble tau protein is lower in affected regions of these diseases, and we previously reported that tau knockout mice display motor and cognitive behavioral abnormities, brain atrophy, neuronal death in substantia nigra, and iron accumulation in the brain that all emerged between 6 and 12 months of age. This argues for a loss of tau function in AD and PD. We also showed that treatment with the moderate iron chelator, clioquinol (CQ) restored iron levels and prevented neuronal atrophy and attendant behavioral decline in 12-month old tau KO mice when commenced prior to the onset of deterioration (6 months). However, therapies for AD and PD will need to treat the disease once it is already manifest. So, in the current study, we tested whether CQ could also rescue the phenotype of mice with a developed phenotype. We found that 5-month treatment of symptomatic (13 months old) tau KO mice with CQ increased nigral tyrosine hydroxylase phosphorylation (which induces activity) and reversed the motor deficits. Treatment also reversed cognitive deficits and raised BDNF levels in the hippocampus, which was accompanied by attenuated brain atrophy, and reduced iron content in the brain. These data raise the possibility that lowering brain iron levels in symptomatic patients could reverse neuronal atrophy and improve brain function, possibly by elevating neurotrophins.

The neurotoxicity of iron, copper and manganese in Parkinson's and Wilson's diseases

Impaired cellular homeostasis of metals, particularly of Cu, Fe and Mn may trigger neurodegeneration through various mechanisms, notably induction of oxidative stress, promotion of α-synuclein aggregation and fibril formation, activation of microglial cells leading to inflammation and impaired production of metalloproteins. In this article we review available studies concerning Fe, Cu and Mn in Parkinson's disease and Wilson's disease. In Parkinson's disease local dysregulation of iron metabolism in the substantia nigra (SN) seems to be related to neurodegeneration with an increase in SN iron concentration, accompanied by decreased SN Cu and ceruloplasmin concentrations and increased free Cu concentrations and decreased ferroxidase activity in the cerebrospinal fluid. Available data in Wilson's disease suggest that substantial increases in CNS Cu concentrations persist for a long time during chelating treatment and that local accumulation of Fe in certain brain nuclei may occur during the course of the disease. Consequences for chelating treatment strategies are discussed.

The association between chronic obstructive pulmonary disease and Parkinson's disease: a nationwide population-based retrospective cohort study

OBJECTIVE

Previous research has shown that patients with chronic obstructive pulmonary disease (COPD) tend to have a higher risk for cognitive impairment and dementia, a neurodegenerative disorder. The goal of this study was to examine what relationship, if any, exists between COPD and Parkinson's disease (PD), which is also a neurodegenerative disorder.

METHOD

Our study analyzed medical data from the population of Taiwan from 1998 to 2008, with a follow-up period extending to the end of 2010. We identified patients with COPD by the Taiwan National Health Insurance Research Database (NHIRD). We selected a comparison cohort from the general population that was random frequency-matched by age (in 5-year increments), sex and index year, and further analyzed the risk of PD using Cox's regression model, including sex, age and comorbidities.

RESULTS

The study enrolled 20 728 COPD patients (71.1% male, mean age = 68.2 years) and 41 147 controls. The risk of developing PD was 1.37 times greater in patients with COPD compared with patients without COPD after adjusting for age, sex and comorbidities. A significantly increased risk of PD was also found in patients with COPD who had any comorbidity other than diabetes.

CONCLUSION

This nationwide retrospective cohort study demonstrates that PD risk is significantly increased in patients with COPD compared with those of the general population.

Mechanism of the beneficial effect of melatonin in experimental Parkinson's disease

This study aimed to elucidate locomotor activity changes in 6-hydroxydopamine (6-OHDA) induced Parkinson's disease (PD) and investigate the possible beneficial effects of melatonin on altered levels of locomotor activity, cyclooxygenase (COX), prostaglandin E2 (PGE2), nuclear factor kappa-B (NF-κB), nitrate/nitrite and apoptosis. Male Wistar rats were divided into five groups: vehicle (V), melatonin-treated (M), 6-OHDA-injected (6-OHDA), 6-OHDA-injected + melatonin-treated (6-OHDA-Mel) and melatonin treated + 6-OHDA-injected (Mel-6-OHDA). Melatonin was administered intraperitoneally at a dose of 10 mg/kg/day for 30 days in M and Mel-6-OHDA groups, for 7 days in 6-OHDA-Mel group. Experimental PD was created stereotactically via unilateral infusion of 6-OHDA into the medial forebrain bundle (MFB). The 6-OHDA-Mel group started receiving melatonin when experimental PD was created and treatment was continued for 7 days (post-treatment). In the Mel-6-OHDA group, experimental PD was created on the 23rd day of melatonin treatment and continued for the remaining 7 days (pre- and post-treatment). Locomotor activity performance decreased in 6-OHDA group compared with vehicle; however melatonin treatment did not improve this impairment. Nuclear factor kappa Bp65 and Bcl-2 levels were significantly decreased while COX, PGE2 and caspase-3 activity were significantly increased in 6-OHDA group. Melatonin treatment significantly decreased COX, PGE2 and caspase-3 activity, increased Bcl-2 and had no effect on NF-κB levels in experimental PD. 6-Hydroxydopamine injection caused an obvious reduction in TH positive dopaminergic neuron viability as determined by immunohistochemistry. Melatonin supplementation decreased dopaminergic neuron death in 6-OHDA-Mel and Mel-6-OHDA groups compared with 6-OHDA group. Melatonin also protected against 6-OHDA-induced apoptosis, as identified by increment in Bcl-2 levels in dopaminergic neurons. The protective effect of melatonin was more prominent for most parameter following 30 days treatment (pre- and post-) than 7 days post-treatment. In summary, melatonin treatment decreased dopaminergic neuron death in experimental PD model by increasing Bcl-2 protein level and decreasing caspase-3 activity.

Nifedipine and nimodipine protect dopaminergic substantia nigra neurons against axotomy-induced cell death in rat vibrosections via modulating inflammatory responses

Neurodegeneration of cholinergic and dopaminergic neurons is a major hallmark in Alzheimer's or Parkinson's disease, respectively. A dysregulation in calcium homeostasis may be part of this process and counteracting calcium influx may have neuroprotective properties in both diseases. Therefore, we investigated the putative neuroprotective or neurotoxic activity of L-type calcium channel (LTCC) inhibitors on cholinergic and dopaminergic neurons in a rat organotypic vibrosection model. Sagittal or coronal vibrosections (200 μm thick) of postnatal day 10 rats were cultured on 0.4 μm semipermeable membranes for 2 weeks with 10 ng/ml nerve growth factor (NGF) and/or glial-cell line derived neurotrophic factor (GDNF) to maintain survival of cholinergic or dopaminergic neurons, respectively. Thereafter, sections were incubated with 0.1, 1 or 10 μM isradipine, nicardipine or verapamil for 2 weeks to explore cytotoxicity. Alternatively, in order to explore neuroprotective activity, vibrosections were incubated without growth factors but with isradipine or verapamil or with nicardipine, nimodipine or nifedipine from the beginning for 4 weeks. Our data show that all LTCC inhibitors exhibited no neurotoxic effect on cholinergic and dopaminergic neurons. Further, LTCC inhibitors did not have any neuroprotective activity on cholinergic neurons. However, nimodipine and nifedipine significantly enhanced the survival of dopaminergic substantia nigra (SN) but not ventral tegmental area (VTA) neurons, while nicardipine, isradipine and verapamil had no effect. Nifedipine (and more potently GDNF) reduced inflammatory cytokines (macrophage inflammatory protein-2, tumor necrosis factor-α), but did not influence oxidative stress or caspase-3 activity and did not interfere with iron-mediated overload. Our data show that nifedipine and nimodipine are very potent to enhance the survival of axotomized SN neurons, possibly influencing inflammatory processes.

Advances in non-dopaminergic treatments for Parkinson's disease

Since the 1960's treatments for Parkinson's disease (PD) have traditionally been directed to restore or replace dopamine, with L-Dopa being the gold standard. However, chronic L-Dopa use is associated with debilitating dyskinesias, limiting its effectiveness. This has resulted in extensive efforts to develop new therapies that work in ways other than restoring or replacing dopamine. Here we describe newly emerging non-dopaminergic therapeutic strategies for PD, including drugs targeting adenosine, glutamate, adrenergic, and serotonin receptors, as well as GLP-1 agonists, calcium channel blockers, iron chelators, anti-inflammatories, neurotrophic factors, and gene therapies. We provide a detailed account of their success in animal models and their translation to human clinical trials. We then consider how advances in understanding the mechanisms of PD, genetics, the possibility that PD may consist of multiple disease states, understanding of the etiology of PD in non-dopaminergic regions as well as advances in clinical trial design will be essential for ongoing advances. We conclude that despite the challenges ahead, patients have much cause for optimism that novel therapeutics that offer better disease management and/or which slow disease progression are inevitable.

Mitochondrial iron-sulfur cluster dysfunction in neurodegenerative disease

Growing evidence supports a role for mitochondrial iron metabolism in the pathophysiology of neurodegenerative disorders such as Friedreich ataxia (FRDA) and Parkinson disease (PD) as well as in the motor and cognitive decline associated with the aging process. Iron-sulfur enzyme deficits and regional iron accumulation have been observed in each of these conditions. In spite of significant etiological, clinical and pathological differences that exist between FRDA and PD, it is possible that defects in mitochondrial iron-sulfur clusters (ISCs) biogenesis represent a common underlying mechanism leading to abnormal intracellular iron distribution with mitochondrial iron accumulation, oxidative phosphorylation deficits and oxidative stress in susceptible cells and specific regions of the nervous system. Moreover, a similar mechanism may contribute to the age-dependent iron accumulation that occurs in certain brain regions such as the globus pallidus and the substantia nigra. Targeting chelatable iron and reactive oxygen species appear as possible therapeutic options for FRDA and PD, and possibly other age-related neurodegenerative conditions. However, new technology to interrogate ISC synthesis in humans is needed to (i) assess how defects in this pathway contribute to the natural history of neurodegenerative disorders and (ii) develop treatments to correct those defects early in the disease process, before they cause irreversible neuronal cell damage.

The systemic administration of oleoylethanolamide exerts neuroprotection of the nigrostriatal system in experimental Parkinsonism

Oleoylethanolamide (OEA) is an agonist of the peroxisome proliferator-activated receptor α (PPARα) and has been described to exhibit neuroprotective properties when administered locally in animal models of several neurological disorder models, including stroke and Parkinson's disease. However, there is little information regarding the effectiveness of systemic administration of OEA on Parkinson's disease. In the present study, OEA-mediated neuroprotection has been tested on in vivo and in vitro models of 6-hydroxydopamine (6-OH-DA)-induced degeneration. The in vivo model was based on the intrastriatal infusion of the neurotoxin 6-OH-DA, which generates Parkinsonian symptoms. Rats were treated 2 h before and after the 6-OH-DA treatment with systemic OEA (0.5, 1, and 5 mg/kg). The Parkinsonian symptoms were evaluated at 1 and 4 wk after the development of lesions. The functional status of the nigrostriatal system was studied through tyrosine-hydroxylase (TH) and hemeoxygenase-1 (HO-1, oxidation marker) immunostaining as well as by monitoring the synaptophysin content. In vitro cell cultures were also treated with OEA and 6-OH-DA. As expected, our results revealed 6-OH-DA induced neurotoxicity and behavioural deficits; however, these alterations were less severe in the animals treated with the highest dose of OEA (5 mg/kg). 6-OH-DA administration significantly reduced the striatal TH-immunoreactivity (ir) density, synaptophysin expression, and the number of nigral TH-ir neurons. Moreover, 6-OH-DA enhanced striatal HO-1 content, which was blocked by OEA (5 mg/kg). In vitro, 0.5 and 1 μM of OEA exerted significant neuroprotection on cultured nigral neurons. These effects were abolished after blocking PPARα with the selective antagonist GW6471. In conclusion, systemic OEA protects the nigrostriatal circuit from 6-OH-DA-induced neurotoxicity through a PPARα-dependent mechanism.

Iron chelation and multiple sclerosis

Histochemical and MRI studies have demonstrated that MS (multiple sclerosis) patients have abnormal deposition of iron in both gray and white matter structures. Data is emerging indicating that this iron could partake in pathogenesis by various mechanisms, e.g., promoting the production of reactive oxygen species and enhancing the production of proinflammatory cytokines. Iron chelation therapy could be a viable strategy to block iron-related pathological events or it can confer cellular protection by stabilizing hypoxia inducible factor 1α, a transcription factor that normally responds to hypoxic conditions. Iron chelation has been shown to protect against disease progression and/or limit iron accumulation in some neurological disorders or their experimental models. Data from studies that administered a chelator to animals with experimental autoimmune encephalomyelitis, a model of MS, support the rationale for examining this treatment approach in MS. Preliminary clinical studies have been performed in MS patients using deferoxamine. Although some side effects were observed, the large majority of patients were able to tolerate the arduous administration regimen, i.e., 6-8 h of subcutaneous infusion, and all side effects resolved upon discontinuation of treatment. Importantly, these preliminary studies did not identify a disqualifying event for this experimental approach. More recently developed chelators, deferasirox and deferiprone, are more desirable for possible use in MS given their oral administration, and importantly, deferiprone can cross the blood-brain barrier. However, experiences from other conditions indicate that the potential for adverse events during chelation therapy necessitates close patient monitoring and a carefully considered administration regimen.

Nucleoside-2',3'/3',5'-bis(thio)phosphate analogues are promising antioxidants acting mainly via Cu+/Fe2+ ion chelation

We synthesized a series of adenine/guanine 2',3'- or 3',5'-bisphosphate and -bisphosphorothioate analogues, 1-6, as potential Cu(+)/Fe(2+) chelators, with a view to apply them as biocompatible and water-soluble antioxidants. We found that electron paramagnetic resonance (EPR)-monitored inhibition of OH radicals production from H2O2, in an Fe(2+)-H2O2 system, by bisphosphate derivatives 1, 3, and 5 (IC50 = 36, 24, and 40 μM, respectively), was more effective than it was by ethylenediaminetetraacetic acid (EDTA), by a factor of 1.5, 2, and 1.4, respectively. Moreover, 2'-deoxyadenosine-3',5'-bisphosphate, 1, was 1.8- and 4.7-times more potent than adenosine 5'-monophosphate (AMP) and adenosine 5'-diphosphate (ADP), respectively. The bisphosphorothioate derivatives 2, 4, and 6 (IC50 = 92, 50, and 80 μM, respectively), exhibited a dual antioxidant activity, acting as both metal-ion chelators and radical scavengers [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assay data indicates IC50 = 50, 70, and 108 μM vs 27 μM for Trolox]. Only 2'-deoxyadenosine-3',5'-bisphosphorothioate, 2, exhibited good inhibition of Cu(+)-induced H2O2 decomposition (IC50 = 78 vs 224 μM for EDTA). Nucleoside-bisphosphorothioate analogues (2, 4, and 6) were weaker inhibitors than the corresponding bisphosphate analogues (1, 3, and 5), due to intramolecular oxidation under Fenton reaction conditions. (1)H- and (31)P NMR monitored Cu(+) titration of 2, showed that Cu(+) was coordinated by both 3',5'-bisphosphorothioate groups, as well as N7-nitrogen atom, while adenosine-2',3'-bisphosphorothioate, 6, coordinated Cu(+) only by 2',3'-bisphosphorothioate groups. In conclusion, an additional terminal phosphate group on AMP/guanosine 5'-monophosphate (GMP) resulted in Fe(2+)-selective chelators highly potent as Fenton reaction inhibitors.

An iron–dopamine index predicts risk of parkinsonian neurodegeneration in the substantia nigra pars compacta

Imaging of iron and dopamine by laser ablation-inductively coupled plasma-mass spectrometry reveals a risk index for parkinsonian neurodegeneration