Alpha-lipoic acid effects on brain glial functions accompanying double-stranded RNA antiviral and inflammatory signaling

Inhibition of xCT by sulfasalazine alleviates the depression-like behavior of adult male mice subjected to maternal separation stress

Maternal separation (MS) can induce emotional disorders. Our previous study reported that MS resulted in depression-like behavior. In this study, we aimed to explore the role of xCT in depression-like behavior in adult mice subjected to MS stress. Pups were divided into the control group, the control + sulfasalazine (SSZ, 75 mg/kg/day, i.p.) group, the MS group, and the MS+SSZ group. After MS, all pups were raised until PD60. Then, the depression-like behavior was detected by the novelty suppressed feeding (NSF) test, the forced swimming test (FST), and the tail suspension test (TST). The synaptic plasticity was examined by electrophysiological recordings and molecular biotechnology. The data showed that, compared with the control group, the mice in the MS group presented depression-like behavior, impairment of long-term potentiation (LTP), a reduction in the number of astrocytes, and activation of the microglia. Moreover, the expression of xCT was increased in the prefrontal cortex of MS mice, the EAAT2 and the Group Ⅱ metabotropic glutamate receptors (mGluR2/3) were decreased, and the level of pro-inflammatory factors was increased in the prefrontal cortex. After the administration with SSZ, the depression-like behavior and the impairment of LTP were alleviated, the number of astrocytes was increased, and the microglial activation was inhibited. Moreover, the levels of EAAT2 and mGluR2/3 were ameliorated, the over-activation of the microglia was mitigated, and the levels of glutamate and pro-inflammatory factors were decreased. In conclusion, the inhibition of xCT by SSZ could alleviate depression-like behavior partly via modulating the homeostasis of the glutamate system and dampening neuroinflammation.

α-Lipoic Acid as Adjunctive Treatment for Schizophrenia: A Randomized Double-Blind Study

BACKGROUND/PURPOSE

There is evidence for low endogenous antioxidant levels and oxidative imbalance in patients with schizophrenia. A previous open-label study with α-lipoic acid (ALA), a potent antioxidant, improved patients' negative and cognitive symptoms and markers of lipid peroxidation. Here we report the results of a randomized double-blind, placebo-controlled study to verify the response of patients with schizophrenia to adjunctive treatment with ALA (100 mg/d) in a 4-month follow-up.

METHODS

We conducted a 16-week, double-blind, placebo-controlled study of ALA at 100 mg/d dosages. We compared negative and positive symptoms, cognitive function, extrapyramidal symptoms, body mass index, and oxidative/inflammatory parameters between placebo and control groups.

RESULTS

We found no significant improvement in body mass index, cognition, psychopathology, antipsychotic adverse effects, or oxidative stress and inflammation in the experimental group compared with placebo. The whole group of patients improved in several measures, indicating a strong placebo effect in this population. A surprising finding was a significant decrease in red blood cells, white blood cells, and platelets in the group treated with ALA.

CONCLUSIONS

The decrease in red blood cells, white blood cells, and platelet counts requires further investigation and attention when prescribing ALA for patients with schizophrenia.

Autism spectrum disorders pathogenesis: Toward a comprehensive model based on neuroanatomic and neurodevelopment considerations

Autism spectrum disorder (ASD) involves alterations in neural connectivity affecting cortical network organization and excitation to inhibition ratio. It is characterized by an early increase in brain volume mediated by abnormal cortical overgrowth patterns and by increases in size, spine density, and neuron population in the amygdala and surrounding nuclei. Neuronal expansion is followed by a rapid decline from adolescence to middle age. Since no known neurobiological mechanism in human postnatal life is capable of generating large excesses of frontocortical neurons, this likely occurs due to a dysregulation of layer formation and layer-specific neuronal migration during key early stages of prenatal cerebral cortex development. This leads to the dysregulation of post-natal synaptic pruning and results in a huge variety of forms and degrees of signal-over-noise discrimination losses, accounting for ASD clinical heterogeneities, including autonomic nervous system abnormalities and comorbidities. We postulate that sudden changes in environmental conditions linked to serotonin/kynurenine supply to the developing fetus, throughout the critical GW7 - GW20 (Gestational Week) developmental window, are likely to promote ASD pathogenesis during fetal brain development. This appears to be driven by discrete alterations in differentiation and patterning mechanisms arising from in utero RNA editing, favoring vulnerability outcomes over plasticity outcomes. This paper attempts to provide a comprehensive model of the pathogenesis and progression of ASD neurodevelopmental disorders.

Gliotoxicity and Glioprotection: the Dual Role of Glial Cells

Glial cells (astrocytes, oligodendrocytes and microglia) are critical for the central nervous system (CNS) in both physiological and pathological conditions. With this in mind, several studies have indicated that glial cells play key roles in the development and progression of CNS diseases. In this sense, gliotoxicity can be referred as the cellular, molecular, and neurochemical changes that can mediate toxic effects or ultimately lead to impairment of the ability of glial cells to protect neurons and/or other glial cells. On the other hand, glioprotection is associated with specific responses of glial cells, by which they can protect themselves as well as neurons, resulting in an overall improvement of the CNS functioning. In addition, gliotoxic events, including metabolic stresses, inflammation, excitotoxicity, and oxidative stress, as well as their related mechanisms, are strongly associated with the pathogenesis of neurological, psychiatric and infectious diseases. However, glioprotective molecules can prevent or improve these glial dysfunctions, representing glial cells-targeting therapies. Therefore, this review will provide a brief summary of types and functions of glial cells and point out cellular and molecular mechanisms associated with gliotoxicity and glioprotection, potential glioprotective molecules and their mechanisms, as well as gliotherapy. In summary, we expect to address the relevance of gliotoxicity and glioprotection in the CNS homeostasis and diseases.

Gut Reactions: How Far Are We from Understanding and Manipulating the Microbiota Complexity and the Interaction with Its Host? Lessons from Autism Spectrum Disorder Studies

Autism is a group of neurodevelopmental disorders, characterized by early onset difficulties in social communication and restricted, repetitive behaviors and interests. It is characterized by familial aggregation, suggesting that genetic factors play a role in disease development, in addition to developmentally early environmental factors. Here, we review the role of the gut microbiome in autism, as it has been characterized in case-control studies. We discuss how methodological differences may have led to inconclusive or contradictory results, even though a disproportion between harmful and beneficial bacteria is generally described in autism. Furthermore, we review the studies concerning the effects of gut microbial-based and dietary interventions on autism symptoms. Also, in this case, the results are not comparable due to the lack of standardized methods. Therefore, autism-specific microbiome signatures and, consequently, possible microbiome-oriented interventions are far from being recognized. We argue that a multi-omic longitudinal implementation may be useful to study metabolic changes connected to microbiome changes.

The neuropsychiatric manifestations of COVID-19: Interactions with psychiatric illness and pharmacological treatment

The recent outbreak of the corona virus disease (COVID-19) has had major global impact. The relationship between severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection and psychiatric diseases is of great concern, with an evident link between corona virus infections and various central and peripheral nervous system manifestations. Unmitigated neuro-inflammation has been noted to underlie not only the severe respiratory complications of the disease but is also present in a range of neuro-psychiatric illnesses. Several neurological and psychiatric disorders are characterized by immune-inflammatory states, while treatments for these disorders have distinct anti-inflammatory properties and effects. With inflammation being a common contributing factor in SARS-CoV-2, as well as psychiatric disorders, treatment of either condition may affect disease progression of the other or alter response to pharmacological treatment. In this review, we elucidate how viral infections could affect pre-existing psychiatric conditions and how pharmacological treatments of these conditions may affect overall progress and outcome in the treatment of SARS-CoV-2. We address whether any treatment-induced benefits and potential adverse effects may ultimately affect the overall treatment approach, considering the underlying dysregulated neuro-inflammatory processes and potential drug interactions. Finally, we suggest adjunctive treatment options for SARS-CoV-2-associated neuro-psychiatric symptoms.

Genome, Environment, Microbiome and Metabolome in Autism (GEMMA) Study Design: Biomarkers Identification for Precision Treatment and Primary Prevention of Autism Spectrum Disorders by an Integrated Multi-Omics Systems Biology Approach

Autism Spectrum Disorder (ASD) affects approximately 1 child in 54, with a 35-fold increase since 1960. Selected studies suggest that part of the recent increase in prevalence is likely attributable to an improved awareness and recognition, and changes in clinical practice or service availability. However, this is not sufficient to explain this epidemiological phenomenon. Research points to a possible link between ASD and intestinal microbiota because many children with ASD display gastro-intestinal problems. Current large-scale datasets of ASD are limited in their ability to provide mechanistic insight into ASD because they are predominantly cross-sectional studies that do not allow evaluation of perspective associations between early life microbiota composition/function and later ASD diagnoses. Here we describe GEMMA (Genome, Environment, Microbiome and Metabolome in Autism), a prospective study supported by the European Commission, that follows at-risk infants from birth to identify potential biomarker predictors of ASD development followed by validation on large multi-omics datasets. The project includes clinical (observational and interventional trials) and pre-clinical studies in humanized murine models (fecal transfer from ASD probands) and in vitro colon models. This will support the progress of a microbiome-wide association study (of human participants) to identify prognostic microbiome signatures and metabolic pathways underlying mechanisms for ASD progression and severity and potential treatment response.

Lipoic Acid and Fish Oil Combination Potentiates Neuroinflammation and Oxidative Stress Regulation and Prevents Cognitive Decline of Rats After Sepsis

Sepsis causes organ dysfunction due to an infection, and it may impact the central nervous system. Neuroinflammation and oxidative stress are related to brain dysfunction after sepsis. Both processes affect microglia activation, neurotrophin production, and long-term cognition. Fish oil (FO) is an anti-inflammatory compound, and lipoic acid (LA) is a universal antioxidant substance. They exert neuroprotective roles when administered alone. We aimed at determining the effect of FO+LA combination on microglia activation and brain dysfunction after sepsis. Microglia cells from neonatal pups were co-treated with lipopolysaccharide (LPS) and FO or LA, alone or combined, for 24 h. Cytokine levels were measured. Wistar rats were subjected to sepsis by cecal ligation and perforation (CLP) and treated orally with FO, LA, or FO+LA. At 24 h after surgery, the hippocampus, prefrontal cortex, and total cortex were obtained and assayed for levels of cytokines, myeloperoxidase (MPO) activity, protein carbonyls, superoxide dismutase (SOD), and catalase (CAT) activity. At 10 days after surgery, brain-derived neurotrophic factor (BDNF) levels were determined and behavioral tests were performed. The combination diminished in vitro levels of pro-inflammatory cytokines. The combination reduced TNF-α in the cortex, IL-1β in the prefrontal cortex, as well as MPO activity, and decreased protein carbonyls formation in all structures. The combination enhanced catalase activity in the prefrontal cortex and hippocampus, elevated BDNF levels in all structures, and prevented behavioral impairment. In summary, the combination was effective in preventing cognitive damage by reducing neuroinflammation and oxidative stress and increasing BDNF levels.

A New Approach to Treating Neurodegenerative Otologic Disorders

Hearing loss, the most common neurological disorder and the fourth leading cause of years lived with disability, can have profound effects on quality of life. The impact of this "invisible disability," with significant consequences, economic and personal, is most substantial in low- and middle-income countries, where >80% of affected people live. Given the importance of hearing for communication, enjoyment, and safety, with up to 500 million affected globally at a cost of nearly $800 billion/year, research on new approaches toward prevention and treatment is attracting increased attention. The consequences of noise pollution are largely preventable, but irreversible hearing loss can result from aging, disease, or drug side effects. Once damage occurs, treatment relies on hearing aids and cochlear implants. Preventing, delaying, or reducing some degree of hearing loss may be possible by avoiding excessive noise and addressing major contributory factors such as cardiovascular risk. However, given the magnitude of the problem, these interventions alone are unlikely to be sufficient. Recent advances in understanding principal mechanisms that govern hearing function, together with new drug discovery paradigms designed to identify efficacious therapies, bode well for pharmaceutical intervention. This review surveys various causes of loss of auditory function and discusses potential neurological underpinnings, including mitochondrial dysfunction. Mitochondria mitigate cell protection, survival, and function and may succumb to cumulative degradation of energy production and performance; the end result is cell death. Energy-demanding neurons and vestibulocochlear hair cells are vulnerable to mitochondrial dysfunction, and hearing impairment and deafness are characteristic of neurodegenerative mitochondrial disease phenotypes. Beyond acting as cellular powerhouses, mitochondria regulate immune responses to infections, and studies of this phenomenon have aided in identifying nuclear factor kappa B and nuclear factor erythroid 2-related factor 2/antioxidant response element signaling as targets for discovery of otologic drugs, respectively, suppressing or upregulating these pathways. Treatment with free radical scavenging antioxidants is one therapeutic approach, with lipoic acid and corresponding carnitine esters exhibiting improved biodistribution and other features showing promise. These compounds are also histone deacetylase (HDAC) inhibitors, adding epigenetic modulation to the mechanistic milieu through which they act. These data suggest that new drugs targeting mitochondrial dysfunction and modulating epigenetic pathways via HDAC inhibition or other mechanisms hold great promise.

Mitochondrial Agents for Bipolar Disorder

Background

Bipolar disorder is a chronic and often debilitating illness. Current treatment options (both pharmaco- and psychotherapy) have shown efficacy, but for many leave a shortfall in recovery. Advances in the understanding of the pathophysiology of bipolar disorder suggest that interventions that target mitochondrial dysfunction may provide a therapeutic benefit.

Methods

This review explores the current and growing theoretical rationale as well as existing preclinical and clinical data for those therapies aiming to target the mitochondrion in bipolar disorder. A Clinicaltrials.gov and ANZCTR search was conducted for complete and ongoing trials on mitochondrial agents used in psychiatric disorders. A PubMed search was also conducted for literature published between January 1981 and July 2017. Systematic reviews, randomized controlled trials, observational studies, case series, and animal studies with an emphasis on agents affecting mitochondrial function and its role in bipolar disorder were included. The search was augmented by manually searching the references of key papers and related literature. The results were presented as a narrative review.

Results

Mitochondrial agents offer new horizons in mood disorder treatment. While some negative effects have been reported, most compounds are overall well tolerated and have generally benign side-effect profiles.

Conclusions

The study of neuroinflammation, neurodegeneration, and mitochondrial function has contributed the understanding of bipolar disorder's pathophysiology. Agents targeting these pathways could be a potential therapeutic strategy. Future directions include identification of novel candidate mitochondrial modulators as well as rigorous and well-powered clinical trials.

α-Lipoic Acid as Adjunctive Treatment for Schizophrenia: An Open-Label Trial

PURPOSE/BACKGROUND

Accumulating evidence suggests an involvement of oxidative stress in the pathophysiology of schizophrenia. This offers a hypothesis-derived therapeutic approach to hinder oxidative damage and its clinical sequelae. α-Lipoic acid (ALA) is a powerful natural antioxidant indicated to treat diabetic neuropathy.

METHODS/PROCEDURES

In this pilot investigation, we administered ALA (100 mg/d) for 4 months, as an adjunct to antipsychotic medication, to 10 patients with schizophrenia.

FINDINGS/RESULTS

We found robust improvement in measures of psychopathology (63.9% reduction in Brief Psychiatric Rating Scale scores), neurocognitive parameters, extrapyramidal symptoms, and decreased lipid peroxidation.

IMPLICATIONS/CONCLUSIONS

If larger, double-blind, placebo-controlled studies confirm these preliminary findings, ALA could prove useful as adjunctive therapy for schizophrenia.

Functional Medicine Approach to Traumatic Brain Injury

Background: The U.S. military has seen dramatic increases in traumatic brain injuries (TBIs) among military personnel due to the nature of modern-day conflicts. Conventional TBI treatment for secondary brain injuries has suboptimal success rates, and patients, families, and healthcare professionals are increasingly turning to alternative medicine treatments. Objective: Effective treatments for the secondary injury cascades that occur after an initial brain trauma are unclear at this time. The goal of successful treatment options for secondary TBI injuries is to reduce oxidative stress, excitotoxicity, and inflammation while supporting mitochondrial functions and repair of membranes, synapses, and axons. Intervention: A new paradigm of medical care, known as functional medicine, is increasing in popularity and acceptance. Functional medicine combines conventional treatment methods with complementary, genetic, holistic, and nutritional therapies. The approach is to assess the patient as a whole person, taking into account the interconnectedness of the body and its unique reaction to disease, injury, and illness while working to restore balance and optimal health. Functional medicine treatment recommendations often include the use of acupuncture, Ayurveda, chiropractic manipulation, detoxification programs, herbal and homeopathic supplements, specialized diets, massage, meditation and mindfulness practices, neurobiofeedback, nutritional supplements, t'ai chi, and yoga. At present, some of these alternative treatments appear to be beneficial, but more research is needed to validate reported outcomes. Conclusions: Few clinical studies validate the effectiveness of alternative therapies for TBIs. However, further clinical trials and empirical studies warrant further investigation based on some reported positive results from research studies, case histories, anecdotal evidence, and widespread popularity of some approaches. To date, only nutritional therapies and hyperbaric oxygen therapy have shown the most promise and potential for improved outcomes for the treatment of secondary TBI injuries.

Contribution of maternal hypertension to autism etiology in a murine model; cerebellar gene expression

Aim: To study the contribution of maternal hypertension to autism spectrum disorders’ (ASD) phenotype, and gene expression, in a murine model. Materials & methods: To examine the effects of maternal hypertension, we used a well-described transgenic mouse model lacking functional endothelial nitric oxide synthase (eNOS or NOS3). Behavioral testing was performed on male offspring between 8 and 10 weeks of age. Cerebella underwent shotgun transcriptome RNA sequencing. Differentially expressed genes were examined for Gene Ontology enrichment. 2-way-RM-ANOVA, 1-way-ANOVA and Student's t-test were used for statistical analysis. Results & conclusion: Our findings revealed that a deficit in social behavior, the hallmark of ASD, is differentially present in offspring born to hypertensive mothers. Novel ASD-related genes were differentially expressed in the cerebellum, implicating its possible role in ASD etiology. Condensation: Altered uterine environment resulting from maternal hypertension contributes to ASD phenotype, and modifies expression of novel ASD-related genes in cerebella of eNOS heterozygous offspring.

Epigenetic Treatment of Persistent Viral Infections

Preclinical Research Approximately 2,500 years ago, Hippocrates used the word herpes as a medical term to describe lesions that appeared to creep or crawl on the skin, advocating heat as a possible treatment. During the last 50 years, pharmaceutical research has made great strides, and therapeutic options have expanded to include small molecule antiviral agents, protease inhibitors, preventive vaccines for a handful of the papillomaviruses, and even cures for hepatitis C virus infections. However, effective treatments for persistent and recurrent viral infections, particularly the highly prevalent herpesviruses, continue to represent a significant unmet medical need, affecting the majority of the world's population. Exploring the population diversity of the human microbiome and the effects its compositional variances have on the immune system, health, and disease are the subjects of intense investigational research and study. Among the collection of viruses, bacteria, fungi, and single-cell eukaryotes that comprise the human microbiome, the virome has been grossly understudied relative to the influence it exerts on human pathophysiology, much as mitochondria have until recently failed to receive the attention they deserve, given their critical biomedical importance. Fortunately, cellular epigenetic machinery offers a wealth of druggable targets for therapeutic intervention in numerous disease indications, including those outlined above. With advances in synthetic biology, engineering our body's commensal microorganisms to seek out and destroy pathogenic species is clearly on the horizon. This is especially the case given recent breakthroughs in genetic manipulation with tools such as the CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated) gene-editing platforms. Tying these concepts together with our previous work on the microbiome and neurodegenerative and neuropsychiatric diseases, we suggest that, because mammalian cells respond to a viral infection by triggering a cascade of antiviral innate immune responses governed substantially by the cell's mitochondria, small molecule carnitinoids represent a new class of therapeutics with potential widespread utility against many infectious insults. Drug Dev Res 78 : 24-36, 2017.   © 2016 Wiley Periodicals, Inc.

Bipolar Disorder: Role of Inflammation and the Development of Disease Biomarkers

Bipolar disorder is a severe and enduring psychiatric condition which in many cases starts during early adulthood and follows a relapsing and remitting course throughout life. In many patients the disease follows a progressive path with brief periods of inter-episode recovery, sub-threshold symptoms, treatment resistance and increasing functional impairment in the biopsychosocial domains. Knowledge about the neurobiology of bipolar disorder is increasing steadily and evidence from several lines of research implicates immuno-inflammatory mechanisms in the brain and periphery in the etiopathogenesis of this illness and its comorbidities. The main findings are an increase in the levels of proinflammatory cytokines during acute episodes with a decrease in neurotrophic support. Related to these factors are glial cell dysfunction, neuro-endocrine abnormalities and neurotransmitter aberrations which together cause plastic changes in the mood regulating areas of the brain and neuroprogression of the bipolar diathesis. Research in the above mentioned areas is providing an opportunity to discover novel biomarkers for the disease and the field is reaching a point where major breakthroughs can be expected in the not too distant future. It is hoped that with new discoveries fresh avenues will be found to better treat an otherwise recalcitrant disease.

Main path and byways: non-vesicular glutamate release by system xc(-) as an important modifier of glutamatergic neurotransmission

System xc(-) is a cystine/glutamate antiporter that exchanges extracellular cystine for intracellular glutamate. Cystine is intracellularly reduced to cysteine, a building block of GSH. As such, system xc(-) can regulate the antioxidant capacity of cells. Moreover, in several brain regions, system xc(-) is the major source of extracellular glutamate. As such this antiporter is able to fulfill key physiological functions in the CNS, while evidence indicates it also plays a role in certain brain pathologies. Since the transcription of xCT, the specific subunit of system xc(-), is enhanced by the presence of reactive oxygen species and inflammatory cytokines, system xc(-) could be involved in toxic extracellular glutamate release in neurological disorders that are associated with increased oxidative stress and neuroinflammation. System xc(-) has also been reported to contribute to the invasiveness of brain tumors and, as a source of extracellular glutamate, could participate in the induction of peritumoral seizures. Two independent reviews (Pharmacol. Rev. 64, 2012, 780; Antioxid. Redox Signal. 18, 2013, 522), approached from a different perspective, have recently been published on the functions of system xc(-) in the CNS. In this review, we highlight novel achievements and insights covering the regulation of system xc(-) as well as its involvement in emotional behavior, cognition, addiction, neurological disorders and glioblastomas, acquired in the past few years. System xc(-) constitutes an important source of extrasynaptic glutamate in the brain. By modulating the tone of extrasynaptic metabotropic or ionotropic glutamate receptors, it affects excitatory neurotransmission, the threshold for overexcitation and excitotoxicity and, as a consequence, behavior. This review describes the current knowledge of how system xc(-) is regulated and involved in physiological as well as pathophysiological brain functioning.

Lipoic acid and N-acetylcysteine prevent ammonia-induced inflammatory response in C6 astroglial cells: The putative role of ERK and HO1 signaling pathways

Hyperammonemia induces significant changes in the central nervous system (CNS) in direct association with astroglial functions, such as oxidative damage, glutamatergic excitotoxicity, and impaired glutamine synthetase (GS) activity and pro-inflammatory cytokine release. Classically, lipoic acid (LA) and N-acetylcysteine (NAC) exhibit antioxidant and anti-inflammatory activities by increasing glutathione (GSH) biosynthesis and decreasing pro-inflammatory mediator levels in glial cells. Thus, we evaluated the protective effects of LA and NAC against ammonia cytotoxicity in C6 astroglial cells. Ammonia decreased GSH levels and increased cytokine release and NFκB transcriptional activation. LA and NAC prevented these effects by the modulation of ERK and HO1 pathways. Taken together, these observations show that LA and NAC prevent the ammonia-induced inflammatory response.

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.