The coenzyme Q10 status of the brain regions of Parkinson's disease patients

Mitochondrial dysfunction in Parkinson's disease - a key disease hallmark with therapeutic potential

Mitochondrial dysfunction is strongly implicated in the etiology of idiopathic and genetic Parkinson's disease (PD). However, strategies aimed at ameliorating mitochondrial dysfunction, including antioxidants, antidiabetic drugs, and iron chelators, have failed in disease-modification clinical trials. In this review, we summarize the cellular determinants of mitochondrial dysfunction, including impairment of electron transport chain complex 1, increased oxidative stress, disturbed mitochondrial quality control mechanisms, and cellular bioenergetic deficiency. In addition, we outline mitochondrial pathways to neurodegeneration in the current context of PD pathogenesis, and review past and current treatment strategies in an attempt to better understand why translational efforts thus far have been unsuccessful.

Biosynthesis, Deficiency, and Supplementation of Coenzyme Q

Originally identified as a key component of the mitochondrial respiratory chain, Coenzyme Q (CoQ or CoQ₁₀ for human tissues) has recently been revealed to be essential for many different redox processes, not only in the mitochondria, but elsewhere within other cellular membrane types. Cells rely on endogenous CoQ biosynthesis, and defects in this still-not-completely understood pathway result in primary CoQ deficiencies, a group of conditions biochemically characterised by decreased tissue CoQ levels, which in turn are linked to functional defects. Secondary CoQ deficiencies may result from a wide variety of cellular dysfunctions not directly linked to primary synthesis. In this article, we review the current knowledge on CoQ biosynthesis, the defects leading to diminished CoQ₁₀ levels in human tissues and their associated clinical manifestations.

Coenzyme Q10 Metabolism: A Review of Unresolved Issues

The variable success in the outcome of randomised controlled trials supplementing coenzyme Q10 (CoQ10) may in turn be associated with a number of currently unresolved issues relating to CoQ10 metabolism. In this article, we have reviewed what is currently known about these factors and where gaps in knowledge exist that need to be further elucidated. Issues addressed include (i) whether the bioavailability of CoQ10 could be improved; (ii) whether CoQ10 could be administered intravenously; (iii) whether CoQ10 could be administered via alternative routes; (iv) whether CoQ10 can cross the blood-brain barrier; (v) how CoQ10 is transported into and within target cells; (vi) why some clinical trials supplementing CoQ10 may have been unsuccessful; and (vii) which is the most appropriate tissue for the clinical assessment of CoQ10 status.

Mitochondrial Dysfunction and Neurodegenerative Disorders: Role of Nutritional Supplementation

Mitochondrial dysfunction has been implicated in the pathogenesis of a number of neurodegenerative disorders, including Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis, multisystem atrophy, and progressive supranuclear palsy. This article is concerned specifically with mitochondrial dysfunction as defined by reduced capacity for ATP production, the role of depleted levels of key nutritionally related metabolites, and the potential benefit of supplementation with specific nutrients of relevance to normal mitochondrial function in the above neurodegenerative disorders. The article provides a rationale for a combination of CoQ10, B-vitamins/NADH, L-carnitine, vitamin D, and alpha-lipoic acid for the treatment of the above neurodegenerative disorders.

Evidence for Oxidative Pathways in the Pathogenesis of PD: Are Antioxidants Candidate Drugs to Ameliorate Disease Progression?

Parkinson’s disease (PD) is a progressive neurodegenerative disorder that arises due to a complex and variable interplay between elements including age, genetic, and environmental risk factors that manifest as the loss of dopaminergic neurons. Contemporary treatments for PD do not prevent or reverse the extent of neurodegeneration that is characteristic of this disorder and accordingly, there is a strong need to develop new approaches which address the underlying disease process and provide benefit to patients with this debilitating disorder. Mitochondrial dysfunction, oxidative damage, and inflammation have been implicated as pathophysiological mechanisms underlying the selective loss of dopaminergic neurons seen in PD. However, results of studies aiming to inhibit these pathways have shown variable success, and outcomes from large-scale clinical trials are not available or report varying success for the interventions studied. Overall, the available data suggest that further development and testing of novel therapies are required to identify new potential therapies for combating PD. Herein, this review reports on the most recent development of antioxidant and anti-inflammatory approaches that have shown positive benefit in cell and animal models of disease with a focus on supplementation with natural product therapies and selected synthetic drugs.

Coenzyme Q10 and Parkinsonian Syndromes: A Systematic Review

Coenzyme Q₁₀ (CoQ₁₀) has an important role as an antioxidant. Being that oxidative stress is one of the mechanisms involved in the pathogenesis of Parkinson’s disease (PD) and other neurodegenerative diseases, several studies addressed the concentrations of CoQ₁₀ in the different tissues of patients with PD and other parkinsonian syndromes (PS), trying to elucidate their value as a marker of these diseases. Other studies addressed the potential therapeutic role of CoQ₁₀ in PD and PS. We underwent a systematic review and a meta-analysis of studies measuring tissue CoQ₁₀ concentrations which shows that, compared with controls, PD patients have decreased CoQ₁₀ levels in the cerebellar cortex, platelets, and lymphocytes, increased total and oxidized CoQ₁₀ levels in the cerebrospinal fluid and a non-significant trend toward decreased serum/plasma CoQ₁₀ levels. Patients with multiple system atrophy (MSA) showed decreased CoQ₁₀ levels in the cerebellar cortex, serum/plasma, cerebrospinal fluid, and skin fibroblasts. Patients with Lewy body dementia (LBD) showed decreased cerebellar cortex CoQ₁₀, and those with progressive supranuclear palsy (PSP) had decreased CoQ₁₀ levels in the cerebrospinal fluid. A previous meta-analysis of studies addressing the therapeutic effects of CoQ₁₀ in PD showed a lack of improvement in patients with early PD. Results of the treatment with CoQ₁₀ in PSP should be considered preliminary. The potential role of CoQ₁₀ therapy in the MSA and selected groups of PD patients deserves future studies.

Opposite Roles of Co-enzyme Q10 and Formaldehyde in Neurodegenerative Diseases

Most of neurodegenerative diseases (NDD) have no cure. The common etiology of neurodegenerations is unclear. Air pollutant-gaseous formaldehyde is notoriously known to induce demyelination and cognitive impairments. Unexpectedly, an amount of formaldehyde has been detected in the brains. Multiple factors can induce the generation and accumulation of endogenous formaldehyde. Excessive formaldehyde can induce oxidative stress to generate H2O2; in turn, H2O2 promote formaldehyde production. Clinical investigations have shown that an abnormal high level of formaldehyde but low level of coenzyme Q10 (coQ10) was observed in patients with NDD. Further studies have proven that excessive formaldehyde directly inactivates coQ10, reduces the ATP generation, enhances oxidative stress, initiates inflammation storm, induces demyelination; subsequently, it results in neurodegeneration. Although the low water solubility of coQ10 limits its clinical application, nanomicellar water-soluble coQ10 exhibits positive therapeutical effects. Hence, nanopackage of coQ10 may be a promising strategy for treating NDD.

Coenzyme Q10 effects in neurological diseases

Coenzyme Q10 (CoQ10), a lipophilic substituted benzoquinone, is present in animal and plant cells. It is endogenously synthetized in every cell and involved in a variety of cellular processes. CoQ10 is an obligatory component of the respiratory chain in inner mitochondrial membrane. In addition, the presence of CoQ10 in all cellular membranes and in blood. It is the only endogenous lipid antioxidant. Moreover, it is an essential factor for uncoupling protein and controls the permeability transition pore in mitochondria. It also participates in extramitochondrial electron transport and controls membrane physicochemical properties. CoQ10 effects on gene expression might affect the overall metabolism. Primary changes in the energetic and antioxidant functions can explain its remedial effects. CoQ10 supplementation is safe and well-tolerated, even at high doses. CoQ10 does not cause any serious adverse effects in humans or experimental animals. New preparations of CoQ10 that are less hydrophobic and structural derivatives, like idebenone and MitoQ, are being developed to increase absorption and tissue distribution. The review aims to summarize clinical and experimental effects of CoQ10 supplementations in some neurological diseases such as migraine, Parkinson´s disease, Huntington´s disease, Alzheimer´s disease, amyotrophic lateral sclerosis, Friedreich´s ataxia or multiple sclerosis. Cardiovascular hypertension was included because of its central mechanisms controlling blood pressure in the brainstem rostral ventrolateral medulla and hypothalamic paraventricular nucleus. In conclusion, it seems reasonable to recommend CoQ10 as adjunct to conventional therapy in some cases. However, sometimes CoQ10 supplementations are more efficient in animal models of diseases than in human patients (e.g. Parkinson´s disease) or rather vague (e.g. Friedreich´s ataxia or amyotrophic lateral sclerosis).

Coenzyme Q10, Ageing and the Nervous System: An Overview

The ageing brain is characterised by changes at the physical, histological, biochemical and physiological levels. This ageing process is associated with an increased risk of developing a number of neurological disorders, notably Alzheimer's disease and Parkinson's disease. There is evidence that mitochondrial dysfunction and oxidative stress play a key role in the pathogenesis of such disorders. In this article, we review the potential therapeutic role in these age-related neurological disorders of supplementary coenzyme Q10, a vitamin-like substance of vital importance for normal mitochondrial function and as an antioxidant. This review is concerned primarily with studies in humans rather than in vitro studies or studies in animal models of neurological disease. In particular, the reasons why the outcomes of clinical trials supplementing coenzyme Q10 in these neurological disorders is discussed.

Overview of Beneficial Effects of (Poly)phenol Metabolites in the Context of Neurodegenerative Diseases on Model Organisms

The rise of neurodegenerative diseases in an aging population is an increasing problem of health, social and economic consequences. Epidemiological and intervention studies have demonstrated that diets rich in (poly)phenols can have potent health benefits on cognitive decline and neurodegenerative diseases. Meanwhile, the role of gut microbiota is ever more evident in modulating the catabolism of (poly)phenols to dozens of low molecular weight (poly)phenol metabolites that have been identified in plasma and urine. These metabolites can reach circulation in higher concentrations than parent (poly)phenols and persist for longer periods of time. However, studies addressing their potential brain effects are still lacking. In this review, we will discuss different model organisms that have been used to study how low molecular weight (poly)phenol metabolites affect neuronal related mechanisms gathering critical insight on their potential to tackle the major hallmarks of neurodegeneration.

Coenzyme Q10 supplementation - In ageing and disease

Coenzyme Q₁₀ (CoQ₁₀) is an essential component of the mitochondrial electron transport chain. It is also an antioxidant in cellular membranes and lipoproteins. All cells produce CoQ₁₀ by a specialized cytoplasmatic-mitochondrial pathway. CoQ₁₀ deficiency can result from genetic failure or ageing. Some drugs including statins, widely used by inter alia elderly, may inhibit endogenous CoQ₁₀ synthesis. There are also chronic diseases with lower levels of CoQ₁₀ in tissues and organs. High doses of CoQ₁₀ may increase both circulating and intracellular levels, but there are conflicting results regarding bioavailability. Here, we review the current knowledge of CoQ₁₀ biosynthesis and primary and acquired CoQ₁₀ deficiency, and results from clinical trials based on CoQ₁₀ supplementation. There are indications that supplementation positively affects mitochondrial deficiency syndrome and some of the symptoms of ageing. Cardiovascular disease and inflammation appear to be alleviated by the antioxidant effect of CoQ₁₀. There is a need for further studies and well-designed clinical trials, with CoQ₁₀ in a formulation of proven bioavailability, involving a greater number of participants undergoing longer treatments in order to assess the benefits of CoQ₁₀ treatment in neurodegenerative disorders, as well as in metabolic syndrome and its complications.

Antioxidant Therapeutics in Parkinson's Disease: Current Challenges and Opportunities

Oxidative stress is considered one of the pathological mechanisms that cause Parkinson’s disease (PD), which has led to the investigation of several antioxidants molecules as a potential therapeutic treatment against the disease. Although preclinical studies have demonstrated the efficacy of these compounds to maintain neuronal survival and activity in PD models, these results have not been reflected in clinical trials, antioxidants have not been able to act as disease modifiers in terms of clinical symptoms. Translational medicine currently faces the challenge of redesigning clinical trials to standardize criteria when testing molecules to reduce responses’ variability. Herein, we discuss current challenges and opportunities regarding several non-enzymatic antioxidants’ therapeutic molecules for PD patients’ potential treatment.

Secondary coenzyme Q deficiency in neurological disorders

Coenzyme Q (CoQ) is a ubiquitous lipid serving essential cellular functions. It is the only component of the mitochondrial respiratory chain that can be exogenously absorbed. Here, we provide an overview of current knowledge, controversies, and open questions about CoQ intracellular and tissue distribution, in particular in brain and skeletal muscle. We discuss human neurological diseases and mouse models associated with secondary CoQ deficiency in these tissues and highlight pharmacokinetic and anatomical challenges in exogenous CoQ biodistribution, recent improvements in CoQ formulations and imaging, as well as alternative therapeutical strategies to CoQ supplementation. The last section proposes possible mechanisms underlying secondary CoQ deficiency in human diseases with emphasis on neurological and neuromuscular disorders.

Disorders of Human Coenzyme Q10 Metabolism: An Overview

Coenzyme Q10 (CoQ10) has a number of vital functions in all cells, both mitochondrial and extramitochondrial. In addition to its key role in mitochondrial oxidative phosphorylation, CoQ10 serves as a lipid soluble antioxidant, plays an important role in fatty acid, pyrimidine and lysosomal metabolism, as well as directly mediating the expression of a number of genes, including those involved in inflammation. In view of the central role of CoQ10 in cellular metabolism, it is unsurprising that a CoQ10 deficiency is linked to the pathogenesis of a range of disorders. CoQ10 deficiency is broadly classified into primary or secondary deficiencies. Primary deficiencies result from genetic defects in the multi-step biochemical pathway of CoQ10 synthesis, whereas secondary deficiencies can occur as result of other diseases or certain pharmacotherapies. In this article we have reviewed the clinical consequences of primary and secondary CoQ10 deficiencies, as well as providing some examples of the successful use of CoQ10 supplementation in the treatment of disease.

Anthocyanins and Their Metabolites as Therapeutic Agents for Neurodegenerative Disease

Neurodegenerative diseases, including Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis (ALS), are characterized by the death of neurons within specific regions of the brain or spinal cord. While the etiology of many neurodegenerative diseases remains elusive, several factors are thought to contribute to the neurodegenerative process, such as oxidative and nitrosative stress, excitotoxicity, endoplasmic reticulum stress, protein aggregation, and neuroinflammation. These processes culminate in the death of vulnerable neuronal populations, which manifests symptomatically as cognitive and/or motor impairments. Until recently, most treatments for these disorders have targeted single aspects of disease pathology; however, this strategy has proved largely ineffective, and focus has now turned towards therapeutics which target multiple aspects underlying neurodegeneration. Anthocyanins are unique flavonoid compounds that have been shown to modulate several of the factors contributing to neuronal death, and interest in their use as therapeutics for neurodegeneration has grown in recent years. Additionally, due to observations that the bioavailability of anthocyanins is low relative to that of their metabolites, it has been proposed that anthocyanin metabolites may play a significant part in mediating the beneficial effects of an anthocyanin-rich diet. Thus, in this review, we will explore the evidence evaluating the neuroprotective and therapeutic potential of anthocyanins and their common metabolites for treating neurodegenerative diseases.

Cerebral mitochondrial electron transport chain dysfunction in multiple system atrophy and Parkinson's disease

Multiple system atrophy (MSA) is a neurodegenerative disease characterised by glial cytoplasmic inclusions (GCIs), containing α-synuclein. Mutated COQ2, encoding an enzyme essential for co-enzyme Q10 (CoQ10) biosynthesis, has been associated with MSA. CoQ10 is an electron carrier in the mitochondrial electron transport chain (ETC) and antioxidant. It has been shown to be deficient in MSA brain tissue, thus implicating mitochondrial dysfunction in MSA. To investigate mitochondrial dysfunction in MSA further we examined ETC activity in MSA and control brain tissue, compared with Parkinson's disease (PD) where mitochondrial dysfunction is known to be important. Using cerebellar and occipital white matter ETC complex I, II/III and IV activities were measured spectrophotometrically, selected individual components of the ETC were assessed by immunoblotting and cellular complex IV activity was analysed by enzyme histochemistry. We show decreased complex II/III activity with increased complex I and IV activity in MSA cerebellar white matter. This corresponds with the deficit in CoQ10 previously described in MSA and reflects the high regional pathological burden of GCIs. This study highlights mitochondrial dysfunction in MSA pathogenesis, suggests an influence on selective regional vulnerability to disease and points to shared disease mechanisms in α-synucleinopathies.

Water-soluble CoQ10 as A Promising Anti-aging Agent for Neurological Dysfunction in Brain Mitochondria

Mitochondrial function has been closely associated with normal aging and age-related diseases. Age-associated declines in mitochondrial function, such as changes in oxygen consumption rate, cytochrome c oxidase activity of complex IV, and mitochondrial coenzyme Q (CoQ) levels, begin as early as 12 to 15 months of age in male mouse brains. Brain mitochondrial dysfunction is accompanied by increased accumulation of phosphorylated α-synuclein in the motor cortex and impairment of motor activities, which are similar characteristics of Parkinson's disease. However, these age-associated defects are completely rescued by the administration of exogenous CoQ10 to middle-aged mice via its water solubilization by emulsification in drinking water. Further efforts to develop strategies to enhance the biological availability of CoQ10 to successfully ameliorate age-related brain mitochondrial dysfunction or neurodegenerative disorders may provide a promising anti-aging agent.

Oxidative Stress: Mechanistic Insights into Inherited Mitochondrial Disorders and Parkinson's Disease

Oxidative stress arises when cellular antioxidant defences become overwhelmed by a surplus generation of reactive oxygen species (ROS). Once this occurs, many cellular biomolecules such as DNA, lipids, and proteins become susceptible to free radical-induced oxidative damage, and this may consequently lead to cellular and ultimately tissue and organ dysfunction. Mitochondria, as well as being a source of ROS, are vulnerable to oxidative stress-induced damage with a number of key biomolecules being the target of oxidative damage by free radicals, including membrane phospholipids, respiratory chain complexes, proteins, and mitochondrial DNA (mt DNA). As a result, a deficit in cellular energy status may occur along with increased electron leakage and partial reduction of oxygen. This in turn may lead to a further increase in ROS production. Oxidative damage to certain mitochondrial biomolecules has been associated with, and implicated in the pathophysiology of a number of diseases. It is the purpose of this review to discuss the impact of such oxidative stress and subsequent damage by reviewing our current knowledge of the pathophysiology of several inherited mitochondrial disorders together with our understanding of perturbations observed in the more commonly acquired neurodegenerative disorders such as Parkinson’s disease (PD). Furthermore, the potential use and feasibility of antioxidant therapies as an adjunct to lower the accumulation of damaging oxidative species and hence slow disease progression will also be discussed.

Deficiency of Parkinson's disease-related gene Fbxo7 is associated with impaired mitochondrial metabolism by PARP activation

The Parkinson's disease (PD)-related protein F-box only protein 7 (Fbxo7) is the substrate-recognition component of the Skp1-Cullin-F-box protein E3 ubiquitin ligase complex. We have recently shown that PD-associated mutations in Fbxo7 disrupt mitochondrial autophagy (mitophagy), suggesting a role for Fbxo7 in modulating mitochondrial homeostasis. Here we report that Fbxo7 deficiency is associated with reduced cellular NAD⁺ levels, which results in increased mitochondrial NADH redox index and impaired activity of complex I in the electron transport chain. Under these conditions of compromised respiration, mitochondrial membrane potential and ATP contents are reduced, and cytosolic reactive oxygen species (ROS) production is increased. ROS activates poly (ADP-ribose) polymerase (PARP) activity in Fbxo7-deficient cells. PARP inhibitor restores cellular NAD⁺ content and redox index and ATP pool, suggesting that PARP overactivation is cause of decreased complex I-driven respiration. These findings bring new insight into the mechanism of Fbxo7 deficiency, emphasising the importance of mitochondrial dysfunction in PD.

Nutrition and Lifestyle Intervention on Mood and Neurological Disorders

This group study explored how an intervention of diet and lifestyle, including a vegan diet, fruit and vegetable juicing, nutritional supplements, regular exercise, and destressing techniques, would affect 27 subjects with anxiety, depression, poor memory, dementia, Alzheimer's disease, Parkinson's disease, history of stroke, or multiple sclerosis. Several subjects had overlapping conditions. Videotaped testimonials were obtained describing subjective results. Testimonials stated multiple benefits across all conditions addressed by the study, with subjects often reporting substantial benefits. These results demonstrate that an intervention of diet, juicing, supplements, exercise, and lifestyle may provide considerable benefits for all conditions addressed.

Chronic treatment with coenzyme Q10 reverses restraint stress-induced anhedonia and enhances brain mitochondrial respiratory chain and creatine kinase activities in rats

Several recent studies suggest a close link between mitochondrial dysfunction and depression. Coenzyme Q10 (CoQ10) is a mobile electron carrier in the mitochondrial respiratory chain (MRC) with antioxidant and potential neuroprotective activities. This study investigated the effect of chronic administration of CoQ10 (50, 100, and 200 mg/kg/day, intraperitoneally, for 4 weeks) on anhedonia and on the activities of MRC complexes and creatine kinase in the frontal cortex and hippocampus of Wistar rats subjected to chronic restraint stress (CRS, 6 h × 28 days). Exposure to CRS-induced anhedonic-like behavior (decreased sucrose preference), reduced body weight gain and food intake, increased adrenal gland weight, and altered the activity of the MRC complexes in the brain areas tested. CoQ10 dose-dependently antagonized CRS-induced depressive behavior by increasing sucrose preference (reversal of anhedonia), body weight, and food intake and reducing adrenal gland weight. CoQ10 also enhanced the activities of MRC complexes (I-IV) and creatine kinase in the frontal cortex and hippocampus. Thus, the reversal of CRS-induced anhedonia may be partially mediated by amelioration of brain mitochondrial function. The findings also support the hypothesis that brain energy impairment is involved in the pathophysiology of depression and enhancing mitochondrial function could provide an opportunity for development of a potentially more efficient drug therapy for depression.

Coenzyme Q10 Levels Are Decreased in the Cerebellum of Multiple-System Atrophy Patients

Background

The objective of this study was to evaluate whether the levels of coenzyme Q10 (CoQ10) in brain tissue of multiple system atrophy (MSA) patients differ from those in elderly controls and in patients with other neurodegenerative diseases.

Methods

Flash frozen brain tissue of a series of 20 pathologically confirmed MSA patients [9 olivopontocerebellar atrophy (OPCA) type, 6 striatonigral degeneration (SND) type, and 5 mixed type] was used for this study. Elderly controls (n = 37) as well as idiopathic Parkinson's disease (n = 7), dementia with Lewy bodies (n = 20), corticobasal degeneration (n = 15) and cerebellar ataxia (n = 18) patients were used as comparison groups. CoQ10 was measured in cerebellar and frontal cortex tissue by high performance liquid chromatography.

Results

We detected a statistically significant decrease (by 3–5%) in the level of CoQ10 in the cerebellum of MSA cases (P = 0.001), specifically in OPCA (P = 0.001) and mixed cases (P = 0.005), when compared to controls as well as to other neurodegenerative diseases [dementia with Lewy bodies (P<0.001), idiopathic Parkinson's disease (P<0.001), corticobasal degeneration (P<0.001), and cerebellar ataxia (P = 0.001)].

Conclusion

Our results suggest that a perturbation in the CoQ10 biosynthetic pathway is associated with the pathogenesis of MSA but the mechanism behind this finding remains to be elucidated.

Knockdown of the coenzyme Q synthesis gene Smed-dlp1 affects planarian regeneration and tissue homeostasis

The freshwater planarian is a model organism used to study tissue regeneration that occupies an important position among multicellular organisms. Planarian genomic databases have led to the identification of genes that are required for regeneration, with implications for their roles in its underlying mechanism. Coenzyme Q (CoQ) is a fundamental lipophilic molecule that is synthesized and expressed in every cell of every organism. Furthermore, CoQ levels affect development, life span, disease and aging in nematodes and mice. Because CoQ can be ingested in food, it has been used in preventive nutrition. In this study, we investigated the role of CoQ in planarian regeneration. Planarians synthesize both CoQ9 and rhodoquinone 9 (RQ9). Knockdown of Smed-dlp1, a trans-prenyltransferase gene that encodes an enzyme that synthesizes the CoQ side chain, led to a decrease in CoQ9 and RQ9 levels. However, ATP levels did not consistently decrease in these animals. Knockdown animals exhibited tissue regression and curling. The number of mitotic cells decreased in Smed-dlp1 (RNAi) animals. These results suggested a failure in physiological cell turnover and stem cell function. Accordingly, regenerating planarians died from lysis or exhibited delayed regeneration. Interestingly, the observed phenotypes were partially rescued by ingesting food supplemented with α-tocopherol. Taken together, our results suggest that oxidative stress induced by reduced CoQ9 levels affects planarian regeneration and tissue homeostasis.

Drug therapy for Parkinson’s disease: An update

Parkinson’s disease (PD) is the most common neurodegenerative movement disorder, affecting about 1% of the population above the age of 65. PD is characterized by a selective degeneration of the dopaminergic neurons of the substantia nigra pars compacta. This results in a marked loss of striatal dopamine and the development of the characteristic features of the disease, i.e., bradykinesia, rest tremor, rigidity, gait abnormalities and postural instability. Other types of neurons/neurotransmitters are also involved in PD, including cholinergic, serotonergic, glutamatergic, adenosine, and GABAergic neurotransmission which might have relevance to the motor, non-motor, neuropsychiatric and cognitive disturbances that occur in the course of the disease. The treatment of PD relies on replacement therapy with levodopa (L-dopa), the precursor of dopamine, in combination with a peripheral decarboxylase inhibitor (carbidopa or benserazide). The effect of L-dopa, however, declines over time together with the development of motor complications especially dyskinesia in a significant proportion of patients within 5 years of therapy. Other drugs include dopamine-receptor-agonists, catechol-O-methyltransferase inhibitors, monoamine oxidase type B (MAO-B) inhibitors, anticholinergics and adjuvant therapy with the antiviral drug and the N-methyl-D-aspartate glutamate receptor antagonist amantadine. Although, these medications can result in substantial improvements in parkinsonian symptoms, especially during the early stages of the disease, they are often not successful in advanced disease. Moreover, dopaminergic cell death continues over time, emphasizing the need for neuroprotective or neuroregenerative therapies. In recent years, research has focused on non-dopaminergic approach such as the use of A_2A receptor antagonists: istradefylline and preladenant or the calcium channel antagonist isradipine. Safinamide is a selective and reversible inhibitor of MAO-B, a glutamate receptor inhibitor as well as sodium and calcium channel blocker. Minocycline and pioglitazone are other agents which have been shown to prevent dopaminergic nigral cell loss in animal models of PD. There is also an evidence to suggest a benefit from iron chelation therapy with deferiprone and from the use of antioxidants or mitochondrial function enhancers such as creatine, alpha-lipoic acid, l-carnitine, and coenzyme Q10.

Coenzyme q10 abrogated the 28 days aluminium chloride induced oxidative changes in rat cerebral cortex

Objective:

The present study was designed to elucidate the impact of oral administration of aluminium chloride for 28 days with respect to oxidative stress in the cerebral cortex of female rats. Further, to investigate the potentials of Coenzyme (Co) Q10 (4, 8, and 12 mg/kg, i.p.) in mitigating the detrimental changes.

Materials and Methods:

Biochemical estimations of cerebral lipid peroxidation (LPO), reduced glutathione (GSH), vitamin E and activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were carried out after 28 days of aluminium chloride (AlCl₃) and Co Q10 exposures along with histopathological examination of cerebral cortex of the rats.

Results:

Subacute exposure to AlCl₃(5 mg/kg) led to significant decrease in levels of GSH, vitamin E and activities of SOD, CAT, GPx, and an increase in LPO of cerebral cortex. These aberrations were restored by Co Q10 (12 mg/kg, i.p.). This protection offered was comparable to that of L-deprenyl (1 mg/kg, i.p.) which served as a reference standard. Histopathological evaluations confirmed that the normal cerebral morphology was maintained by Co Q10.

Conclusion:

Thus, AlCl₃ exposure hampers the activities of various antioxidant enzymes and induces oxidative stress in cerebral cortex of female Wistar rats. Supplementation with intraperitoneal Co Q10 abrogated these deleterious effects of AlCl₃.

Nanomicellar formulation of coenzyme Q10 (Ubisol-Q10) effectively blocks ongoing neurodegeneration in the mouse 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine model: potential use as an adjuvant treatment in Parkinson's disease

Although the support for the use of antioxidants, such as coenzyme Q(10) (CoQ(10)), to treat Parkinson's disease (PD) comes from the extensive scientific evidence, the results of conducted thus far clinical trials are inconclusive. It is assumed that the efficacy of CoQ(10) is hindered by insolubility, poor bioavailability, and lack of brain penetration. We have developed a nanomicellar formulation of CoQ(10) (Ubisol-Q(10)) with improved properties, including the brain penetration, and tested its effectiveness in mouse MPTP (1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine) model with the objectives to assess its potential use as an adjuvant therapy for PD. We used a subchronic MPTP model (5-daily MPTP injections), characterized by 50% loss of dopamine neurons over a period of 28 days. Ubisol-Q(10) was delivered in drinking water. Prophylactic application of Ubisol-Q(10), started 2 weeks before the MPTP exposure, significantly offset the neurotoxicity (approximately 50% neurons died in MPTP group vs. 17% in MPTP+ Ubisol-Q(10) group by day 28). Therapeutic application of Ubisol-Q(10), given after the last MPTP injection, was equally effective. At the time of intervention on day 5 nearly 25% of dopamine neurons were already lost, but the treatment saved the remaining 25% of cells, which otherwise would have died by day 28. This was confirmed by cell counts, analyses of striatal dopamine levels, and improved animals' motor skill on a beam walk test. Similar levels of neuroprotection were obtained with 3 different Ubisol-Q(10) concentrations tested, that is, 30 mg, 6 mg, or 3 mg CoQ(10)/kg body weight/day, showing clearly that high doses of CoQ(10) were not required to deliver these effects. Furthermore, the Ubisol-Q(10) treatments brought about a robust astrocytic activation in the brain parenchyma, indicating that astroglia played an active role in this neuroprotection. Thus, we have shown for the first time that Ubisol-Q(10) was capable of halting the neurodegeneration already in progress; however, to maintain it a continuous supplementation of Ubisol-Q(10) was required. The pathologic processes initiated by MPTP resumed if supplementation was withdrawn. We suggest that in addition to brain delivery of powerful antioxidants, Ubisol-Q(10) might have also supported subcellular oxidoreductase systems allowing them to maintain a favorable cellular redox status, especially in astroglia, facilitating their role in neuroprotection. Based on this data further clinical testing of this formulation in PD patients might be justifiable.

Management of the aging risk factor for Parkinson's disease

The aging risk factor for Parkinson's disease is described in terms of specific disease markers including mitochondrial and gene dysfunctions relevant to energy metabolism. This review details evidence for the ability of nutritional agents to manage these aging risk factors. The combination of alpha lipoic acid, acetyl-l-carnitine, coenzyme Q10, and melatonin supports energy metabolism via carbohydrate and fatty acid utilization, assists electron transport and adenosine triphosphate synthesis, counters oxidative and nitrosative stress, and raises defenses against protein misfolding, inflammatory stimuli, iron, and other endogenous or xenobiotic toxins. These effects are supported by gene expression via the antioxidant response element (ARE; Keap/Nrf2 pathway), and by peroxisome proliferator-activated receptor gamma co-activator 1 alpha (PGC-1 alpha), a transcription coactivator, which regulates gene expression for energy metabolism and mitochondrial biogenesis, and maintains the structural integrity of mitochondria. The effectiveness and synergies of the combination against disease risks are discussed in relation to gene action, dopamine cell loss, and the accumulation and spread of pathology via misfolded alpha-synuclein. In addition there are potential synergies to support a neurorestorative role via glial derived neurotrophic factor expression.

Role of platelets in neurodegenerative diseases: a universal pathophysiology

Platelets play an important role in a variety of disorders, namely, cardiovascular, psychosomatic, psychiatric, thrombosis, HIV/AIDS in addition to various neurodegenerative diseases (NDDs). Recent evidence indicates that platelet react to diverse stressors, thereby offering an interesting vantage point for understanding their potential role in contemporary medical research. This review addresses the possible role of platelets as a systemic probe in various NDDs, such as amyotrophic lateral sclerosis, Parkinson's disease, Huntington's disease, Alzheimer's disease, multiple sclerosis, etc. The current review based on published literature, describes a probable link between platelets and pathophysiology of various NDDs. It also discusses how platelets epitomize ultrastructural, morphological, biochemical and molecular changes, highlighting their emerging role as systemic tools in different NDDs.

WITHDRAWN: Coenzyme Q10 for Parkinson's disease

BACKGROUND

A number of preclinical studies in both in vitro and in vivo models of Parkinson's disease have demonstrated that coenzyme Q10 can protect the nigrostriatal dopaminergic system. Some clinical trials have looked at the neuroprotective effects of coenzyme Q10 in patients with early and midstage Parkinson's disease.

OBJECTIVES

To assess the evidence from randomized controlled trials on the efficacy and safety of treatment with coenzyme Q10 compared to placebo in patients with early and midstage Parkinson's disease.

SEARCH METHODS

We searched the Cochrane Movment Disorders Group Trials Register, CENTRAL (The Cochrane Library 2009, Issue 4), MEDLINE (January 1966 to March 2011), and EMBASE (January 1985 to March 2011). We handsearched the references quoted in the identified trials, congress reports from the most important neurological association and movement disorder societies in Europe and America (March 2011), checked reference lists of relevant studies and contacted other researchers.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that compared coenzyme Q10 to placebo for patients who suffered early and midstage primary Parkinson's disease. Studies in which the method of randomization or concealment were unknown were included. Cross-over studies were excluded.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. All disagreements were resolved by consensus between authors and were explained. We attempted to contact the authors of studies for further details if any data were missing and to establish the characteristics of unpublished trials through correspondence with the trial coordinator or principal investigator. Adverse effects information was collected from the trials.

MAIN RESULTS

Four randomized, double-blind, placebo-controlled trials with a total of 452 patients met the inclusion criteria and were included in the review. In overall, there were improvements in activities of daily living (ADL) UPDRS (WMD -3.12, 95% CI -5.88 to -0.36) and Schwab and England (WMD 4.43, 95% CI 0.05 to 8.81) for coenzyme Q10 at 1200 mg/d for 16 months versus placebo.In safety outcomes, only the risk ratios (RR) of pharyngitis (RR 1.04, 95% CI 0.18 to 5.89) and diarrhea (RR 1.39, 95% CI 0.62 to 3.16) are mild elevated between coenzyme Q10 therapy and placebo and there were no differences in the number of withdrawals due to adverse effects (RR 0.61, 95% CI 0.23 to 1.62).

AUTHORS' CONCLUSIONS

Coenzyme Q10 therapy with 1200 mg/d for 16 months was well tolerated by patients with Parkinson's disease. The improvements in ADL UPDRS and Schwab and England were positive, but it need to be further confirmed by larger sample. For total and other subscores of UPDRS, the effects of coenzyme Q10 seemed to be less clear.

Coenzyme Q10 deficiency in patients with Parkinson's disease

Reactive oxygen species (ROS) are well known to contribute to the pathophysiology of Parkinson's disease (PD). Clinical trials of antioxidants are currently underway in PD patients, however, antioxidant research has been hindered by a lack of peripheral biomarkers.

METHODS

Twenty-two patients with PD elected to have a novel antioxidant assessment (Functional Intracellular Assay (FIA), SpectraCell Lab, Houston, TX) performed between 2004 and 2008. Each PD case was compared to four age- and gender-matched controls (n=88) in four separate, random iterations using laboratory data submitted during the same time period. Logistic regression was used to determine the odds of functional deficiency in antioxidant nutrients (i.e., glutathione, coenzyme Q10, selenium, vitamin E and alpha-lipoic acid) by case-control status. The proportion of cases with functional deficiency was also compared to that for controls by chi(2) test.

RESULTS

Compared to cases, PD patients had a significantly greater odds of deficiency in coenzyme Q10 status (OR: 4.7-5.4; 95% CI: 1.5-17.7; P=0.003-0.009) based on FIA results, but not of vitamin E, selenium, lipoic acid, or glutathione (all P>0.05). The proportion of cases with coenzyme Q10 deficiency was also significantly greater in cases than in controls (32-36% vs. 8-9%; P=0.0012-0.006).

CONCLUSIONS

Deficiency of coenzyme Q10 assessed via FIA should be explored as a potential peripheral biomarker of antioxidant status in PD.

Thiamine and Parkinson's disease

Parkinson's disease (PD) is the second most common form of neurodegeneration in the elderly population. PD is clinically characterized by tremors, rigidity, slowness of movement and postural imbalance. A significant association has been demonstrated between PD and low levels of thiamine in the serum, which suggests that elevated thiamine levels might provide protection against PD. Genetic studies have helped identify a number of factors that link thiamine to PD pathology, including the DJ-1 gene, excitatory amino acid transporters (EAATs), the α-ketoglutarate dehydrogenase complex (KGDHC), coenzyme Q10 (CoQ10 or ubiquinone), lipoamide dehydrogenase (LAD), chromosome 7, transcription factor p53, the renin-angiotensin system (RAS), heme oxygenase-1 (HO-1), and poly(ADP-ribose) polymerase-1 gene (PARP-1). Thiamine has also been implicated in PD through its effects on L-type voltage-sensitive calcium channels (L-VSCC), matrix metalloproteinases (MMPs), prostaglandins (PGs), cyclooxygenase-2 (COX-2), reactive oxygen species (ROS), and nitric oxide synthase (NOS). Recent studies highlight a possible relationship between thiamine and PD. Genetic studies provide opportunities to determine which proteins may link thiamine to PD pathology. Thiamine can also act through a number of non-genomic mechanisms that include protein expression, oxidative stress, inflammation, and cellular metabolism. Further studies are needed to determine the benefits of using thiamine as a treatment for PD.

Coenzyme Q10 for Parkinson's disease

BACKGROUND

A number of preclinical studies in both in vitro and in vivo models of Parkinson's disease have demonstrated that coenzyme Q10 can protect the nigrostriatal dopaminergic system. Some clinical trials have looked at the neuroprotective effects of coenzyme Q10 in patients with early and midstage Parkinson's disease.

OBJECTIVES

To assess the evidence from randomized controlled trials on the efficacy and safety of treatment with coenzyme Q10 compared to placebo in patients with early and midstage Parkinson's disease.

SEARCH METHODS

We searched the Cochrane Movment Disorders Group Trials Register, CENTRAL (The Cochrane Library 2009, Issue 4), MEDLINE (January 1966 to March 2011), and EMBASE (January 1985 to March 2011). We handsearched the references quoted in the identified trials, congress reports from the most important neurological association and movement disorder societies in Europe and America (March 2011), checked reference lists of relevant studies and contacted other researchers.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that compared coenzyme Q10 to placebo for patients who suffered early and midstage primary Parkinson's disease. Studies in which the method of randomization or concealment were unknown were included. Cross-over studies were excluded.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. All disagreements were resolved by consensus between authors and were explained. We attempted to contact the authors of studies for further details if any data were missing and to establish the characteristics of unpublished trials through correspondence with the trial coordinator or principal investigator. Adverse effects information was collected from the trials.

MAIN RESULTS

Four randomized, double-blind, placebo-controlled trials with a total of 452 patients met the inclusion criteria and were included in the review. In overall, there were improvements in activities of daily living (ADL) UPDRS (WMD -3.12, 95% CI -5.88 to -0.36) and Schwab and England (WMD 4.43, 95% CI 0.05 to 8.81) for coenzyme Q10 at 1200 mg/d for 16 months versus placebo.In safety outcomes, only the risk ratios (RR) of pharyngitis (RR 1.04, 95% CI 0.18 to 5.89) and diarrhea (RR 1.39, 95% CI 0.62 to 3.16) are mild elevated between coenzyme Q10 therapy and placebo and there were no differences in the number of withdrawals due to adverse effects (RR 0.61, 95% CI 0.23 to 1.62).

AUTHORS' CONCLUSIONS

Coenzyme Q10 therapy with 1200 mg/d for 16 months was well tolerated by patients with Parkinson's disease. The improvements in ADL UPDRS and Schwab and England were positive, but it need to be further confirmed by larger sample. For total and other subscores of UPDRS, the effects of coenzyme Q10 seemed to be less clear.

The promise of neuroprotective agents in Parkinson's disease

Parkinson’s disease (PD) is characterized by loss of dopamine neurons in the substantia nigra of the brain. Since there are limited treatment options for PD, neuroprotective agents are currently being tested as a means to slow disease progression. Agents targeting oxidative stress, mitochondrial dysfunction, and inflammation are prime candidates for neuroprotection. This review identifies Rasagiline, Minocycline, and creatine, as the most promising neuroprotective agents for PD, and they are all currently in phase III trials. Other agents possessing protective characteristics in delaying PD include stimulants, vitamins, supplements, and other drugs. Additionally, combination therapies also show benefits in slowing PD progression. The identification of neuroprotective agents for PD provides us with therapeutic opportunities for modifying the course of disease progression and, perhaps, reducing the risk of onset when preclinical biomarkers become available.

Is coenzyme Q a key factor in aging?

Coenzyme Q (Q) is a key component for bioenergetics and antioxidant protection in the cell. During the last years, research on diseases linked to Q-deficiency has highlighted the essential role of this lipid in cell physiology. Q levels are also affected during aging and neurodegenerative diseases. Therefore, therapies based on dietary supplementation with Q must be considered in cases of Q deficiency such as in aging. However, the low bioavailability of dietary Q for muscle and brain obligates to design new mechanisms to increase the uptake of this compound in these tissues. In the present review we show a complete picture of the different functions of Q in cell physiology and their relationship to age and age-related diseases. Furthermore, we describe the problems associated with dietary Q uptake and the mechanisms currently used to increase its uptake or even its biosynthesis in cells. Strategies to increase Q levels in tissues are indicated.

Coenzyme Q10 and Neurological Diseases

Coenzyme Q10 (CoQ10, or ubiquinone) is a small electron carrier of the mitochondrial respiratory chain with antioxidant properties. CoQ10 supplementation has been widely used for mitochondrial disorders. The rationale for using CoQ10 is very powerful when this compound is primary decreased because of defective synthesis. Primary CoQ10 deficiency is a treatable condition, so heightened "clinical awareness" about this diagnosis is essential. CoQ10 and its analogue, idebenone, have also been widely used in the treatment of other neurodegenerative disorders. These compounds could potentially play a therapeutic role in Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, Friedreich's ataxia, and other conditions which have been linked to mitochondrial dysfunction. This article reviews the physiological roles of CoQ10, as well as the rationale and the role in clinical practice of CoQ10 supplementation in different neurological diseases, from primary CoQ10 deficiency to neurodegenerative disorders.

Coenzyme Q10 effects in neurodegenerative disease

Coenzyme Q10 (CoQ10) is an essential cofactor in the mitochondrial respiratory chain, and as a dietary supplement it has recently gained attention for its potential role in the treatment of neurodegenerative disease. Evidence for mitochondrial dysfunction in neurodegenerative disorders derives from animal models, studies of mitochondria from patients, identification of genetic defects in patients with neurodegenerative disease, and measurements of markers of oxidative stress. Studies of in vitro models of neuronal toxicity and animal models of neurodegenerative disorders have demonstrated potential neuroprotective effects of CoQ10. With this data in mind, several clinical trials of CoQ10 have been performed in Parkinson's disease and atypical Parkinson's syndromes, Huntington's disease, Alzheimer disease, Friedreich's ataxia, and amyotrophic lateral sclerosis, with equivocal findings. CoQ10 is widely available in multiple formulations and is very well tolerated with minimal adverse effects, making it an attractive potential therapy. Phase III trials of high-dose CoQ10 in large sample sizes are needed to further ascertain the effects of CoQ10 in neurodegenerative diseases.