Nicotine and Parkinson's disease: implications for therapy

Clearing the Smoke: What Protects Smokers from Parkinson's Disease?

The link between smoking and a lower risk of Parkinson's disease (PD) is one of the strongest environmental or lifestyle associations in neuroepidemiology. Growing evidence supports the hypothesis that the association is based on a neuroprotective effect of smoking on PD, despite the plausible alternative that smoking serves as a marker for a proximal protective influence without itself conferring benefit. But how smoking could protect against neurodegeneration in PD is not well understood. Of several candidate molecules and mechanisms that have been nominated, nicotine has received the most attention. However, randomized controlled clinical trials of nicotine in PD have failed to demonstrate benefit on motor endpoints, including the NIC-PD study in which recently diagnosed participants were randomly assigned to placebo or nicotine treatment for 1 year. Given these results, the time is right to evaluate the neuroprotective potential of other molecules and biochemical cascades triggered by smoking. Here, we review the evidence supporting smoking's possible protective effect on PD, compounds in tobacco and smoke that might mediate such benefit, and non-causal classes of explanation, including reverse causation and the prospect of shared genetic determinants of smoking and PD resistance. The therapeutic potential of non-nicotine components of smoke is suggested by studies supporting multiple alternative mechanisms ranging from monoamine oxidase inhibitors to gut microbiome disruption to antioxidant response induction by chronic exposure to low levels of carbon monoxide. Rigorous investigation is warranted to evaluate this molecule and others for disease-preventing and disease-modifying activity in PD models and, if warranted, in clinical trials. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Parkinson's Disease is Predominantly a Genetic Disease

The discovery of a pathogenic variant in the alpha-synuclein (SNCA) gene in the Contursi kindred in 1997 indisputably confirmed a genetic cause in a subset of Parkinson's disease (PD) patients. Currently, pathogenic variants in one of the seven established PD genes or the strongest known risk factor gene, GBA1, are identified in ∼15% of PD patients unselected for age at onset and family history. In this Debate article, we highlight multiple avenues of research that suggest an important - and in some cases even predominant - role for genetics in PD aetiology, including familial clustering, high rates of monogenic PD in selected populations, and complete penetrance with certain forms. At first sight, the steep increase in PD prevalence exceeding that of other neurodegenerative diseases may argue against a predominant genetic etiology. Notably, the principal genetic contribution in PD is conferred by pathogenic variants in LRRK2 and GBA1 and, in both cases, characterized by an overall late age of onset and age-related penetrance. In addition, polygenic risk plays a considerable role in PD. However, it is likely that, in the majority of PD patients, a complex interplay of aging, genetic, environmental, and epigenetic factors leads to disease development.

Future Directions for Developing Non-dopaminergic Strategies for the Treatment of Parkinson's Disease

The symptomatic treatment of Parkinson's disease (PD) has been dominated by the use of dopaminergic medication, but significant unmet need remains, much of which is related to non-motor symptoms and the involvement of non-dopaminergic transmitter systems. As such, little has changed in the past decades that has led to milestone advances in therapy and significantly improved treatment paradigms and patient outcomes, particularly in relation to symptoms unresponsive to levodopa. This review has looked at how pharmacological approaches to treatment are likely to develop in the near and distant future and will focus on two areas: 1) novel non-dopaminergic pharmacological strategies to control motor symptoms; and 2) novel non-dopaminergic approaches for the treatment of non-motor symptoms. The overall objective of this review is to use a 'crystal ball' approach to the future of drug discovery in PD and move away from the more traditional dopamine-based treatments. Here, we discuss promising non-dopaminergic and 'dirty drugs' that have the potential to become new key players in the field of Parkinson's disease treatment.

Senolytic and senomorphic secondary metabolites as therapeutic agents in Drosophila melanogaster models of Parkinson's disease

Drosophila melanogaster is a valuable model organism for a wide range of biological exploration. The well-known advantages of D. melanogaster include its relatively simple biology, the ease with which it is genetically modified, the relatively low financial and time costs associated with their short gestation and life cycles, and the large number of offspring they produce per generation. D. melanogaster has facilitated the discovery of many significant insights into the pathology of Parkinson's disease (PD) and has served as an excellent preclinical model of PD-related therapeutic discovery. In this review, we provide an overview of the major D. melanogaster models of PD, each of which provide unique insights into PD-relevant pathology and therapeutic targets. These models are discussed in the context of their past, current, and future potential use for studying the utility of secondary metabolites as therapeutic agents in PD. Over the last decade, senolytics have garnered an exponential interest in their ability to mitigate a broad spectrum of diseases, including PD. Therefore, an emphasis is placed on the senolytic and senomorphic properties of secondary metabolites. It is expected that D. melanogaster will continue to be critical in the effort to understand and improve treatment of PD, including their involvement in translational studies focused on secondary metabolites.

Transdermal Nicotine Treatment and Progression of Early Parkinson's Disease

BACKGROUND: Epidemiologic studies show that smokers have a lower incidence of Parkinson’s disease. Nicotine has been hypothesized to slow progression in early Parkinson’s disease. METHODS: In a double-blind, placebo-controlled multicenter trial, we randomly assigned patients with Parkinson’s disease, diagnosed within 18 months, who were in Hoehn and Yahr disease stage less than or equal to 2 (range from 0 to 5; higher scores indicate greater impairment), who were therapy naïve (except for stable monoamine-oxidase-B inhibition), and not requiring dopaminergic therapy, to transdermal nicotine or placebo. The primary end point was change in Unified Parkinson’s Disease Rating Scale parts I–III (Total UPDRS) score (range from 0 to 172; higher scores indicate greater impairment) between baseline and 60 weeks (52 weeks of trial therapy, 8 weeks of washout). The first secondary end point was change in Total UPDRS from baseline to 52 weeks. Differences between groups were estimated using the Hodges–Lehmann (HL) method and tested with the exact two-sided stratified Mann–Whitney–Wilcoxon test according to the intention-to-treat principle. RESULTS: Among 163 participants, 101 were assessed for the primary end point. Mean worsening of Total UPDRS was 3.5 in the placebo versus 6.0 in the nicotine group (HL-difference with 95% CI: –3 [–6 to 0], P=0.06). For the first secondary end point, analysis of 138 participants showed a mean worsening of 5.4 in the placebo versus 9.1 in the nicotine group (HL-difference with 95% CI: –4 [–7 to –1]). Dropout was mainly because of early treatment discontinuation or adverse events. Cutaneous adverse effects at the patch application site were common. In all, 34.6% of participants initiated dopaminergic therapy during participation. CONCLUSIONS: One-year transdermal nicotine treatment did not slow progression in early Parkinson’s disease. (Funded by the Michael J. Fox Foundation for Parkinson’s Research and others; ClinicalTrials.gov number, NCT01560754; EudraCT number, 2010-020299-42.)

Nicotine-mediated effects in neuronal and mouse models of synucleinopathy

Introduction

Alpha-synuclein (α-Syn) aggregation, transmission, and contribution to neurotoxicity represent central mechanisms underlying Parkinson's disease. The plant alkaloid "nicotine" was reported to attenuate α-Syn aggregation in different models, but its precise mode of action remains unclear.

Methods

In this study, we investigated the effect of 2-week chronic nicotine treatment on α-Syn aggregation, neuroinflammation, neurodegeneration, and motor deficits in D-line α-Syn transgenic mice. We also established a novel humanized neuronal model of α-Syn aggregation and toxicity based on treatment of dopaminergic neurons derived from human induced pluripotent stem cells (iPSC) with α-Syn preformed fibrils (PFF) and applied this model to investigate the effects of nicotine and other compounds and their modes of action.

Results and discussion

Overall, our results showed that nicotine attenuated α-Syn-provoked neuropathology in both models. Moreover, when investigating the role of nicotinic acetylcholine receptor (nAChR) signaling in nicotine's neuroprotective effects in iPSC-derived dopaminergic neurons, we observed that while α4-specific antagonists reduced the nicotine-induced calcium response, α4 agonists (e.g., AZD1446 and anatabine) mediated similar neuroprotective responses against α-Syn PFF-provoked neurodegeneration. Our results show that nicotine attenuates α-Syn-provoked neuropathology in vivo and in a humanized neuronal model of synucleinopathy and that activation of α4β2 nicotinic receptors might mediate these neuroprotective effects.

Lynx1 and the family of endogenous mammalian neurotoxin-like proteins and their roles in modulating nAChR function

The promise of nicotinic receptors as a therapeutic target has yet to be fully realized, despite solid data supporting their involvement in neurological and neuropsychiatric diseases. The reasons for this are likely complex and manifold, having to do with the widespread action of the cholinergic system and the biophysical mechanism of action of nicotinic receptors leading to fast desensitization and down-regulation. Conventional drug development strategies tend to focus on receptor subtype-specific action of candidate therapeutics, although the broad agonist, nicotine, is being explored in the clinic. The potential negative effects of nicotine make the search for alternate strategies warranted. Prototoxins are a promising yet little-explored avenue of nicotinic receptor drug development. Nicotinic receptors in the brain belong to a complex of proteins, including those that bind to the extracellular face of the receptor, as well as chaperones that bind the intracellular domain, etc. Lynx prototoxins have allosteric modularity effects on receptor function and number and have been implicated in complex in vivo processes such as neuroplasticity, learning, and memory. Their mechanism of action and binding specificity on sets of nAChR subtypes present intriguing possibilities for more efficacious and nuanced therapeutic targeting than nicotinic receptor subtypes alone. An allosteric drug may restrict its actions to physiologically relevant time points, which tend to be correlated with salient events which would be encoded into long-term memory storage. Rather than blanketing the brain with a steady and prolonged elevation of agonist, an allosteric nAChR compound could avoid side effects and loss of efficacy over time. This review details the potential strengths and challenges of prototoxin proteins as therapeutic targets, and some of the utility of such therapeutics based on the emerging understanding of cholinergic signaling in a growing number of complex neural processes.

Nicotine's effect on cognition, a friend or foe?

Tobacco smoking is a preventable cause of morbidity and mortality throughout the world. Smoking comes in form of absorption of many compounds, among which nicotine is the main psychoactive component of tobacco and its positive and negative reinforcement effects are proposed to be the key mechanism for the initiation and maintenance of smoking. Growing evidence suggests that the cognitive enhancement effects of nicotine may also contribute to the difficulty of quitting smoking, especially in individuals with psychiatric disorders. In this review, we first introduce the beneficial effect of nicotine on cognition including attention, short-term memory and long-term memory. We next summarize the beneficial effect of nicotine on cognition under pathological conditions, including Alzheimer's disease, Parkinson's disease, Schizophrenia, Stress-induced Anxiety, Depression, and drug-induced memory impairment. The possible mechanism underlying nicotine's effect is also explored. Finally, nicotine's detrimental effect on cognition is discussed, including in the prenatal and adolescent periods, and high-dose nicotine- and withdrawal-induced memory impairment is emphasized. Therefore, nicotine serves as both a friend and foe. Nicotine-derived compounds could be a promising strategy to alleviate neurological disease-associated cognitive deficit, however, due to nicotine's detrimental effect, continued educational programs and public awareness campaigns are needed to reduce tobacco use among pregnant women and smoking should be quitted even if it is e-cigarette, especially for the adolescents.

Characteristics of Cognitive Impairment and Their Relationship With Total Cerebral Small Vascular Disease Score in Parkinson's Disease

Background

This study aimed to investigate the characteristics of cognitive dysfunctions and their relationship with total cerebral small vascular disease (CSVD) in Parkinson’s disease (PD).

Methods

A total of 174 idiopathic PD patients who underwent brain magnetic resonance imaging (MRI) were recruited. Demographic information, vascular disease risk factors, motor function (MDS-UPDRS III score), and cognitive level (MoCA, MMSE) were collected for these patients. The total CSVD burden was scored based on lacunes, enlarged perivascular spaces (EPVS), high-grade white matter hyperintensities (WMH), and cerebral microbleeds (CMBs) for each subject.

Results

Cognitive scores on MoCA for language, delayed recall, and orientation were significantly reduced in PD patients with CSVD burden ≥ 1 than in those with CSVD burden = 0. Educational level, PDQ 39, and CSVD burden were significantly associated with MoCA scores in individuals with PD. For the whole group, the full model accounted for 33.6% variation in total MoCA scores. In which, CSVD burden explained 2.7% of the results, and the detection of lacunes, WMH, EPVS, and strictly lobar CMBs were significantly correlated with MoCA scores. The stability of the outcomes was confirmed by sensitivity analysis.

Conclusion

CSVD can independently contribute to cognitive decline in PD and cause damage in specific cognitive domains. Promoting neurovascular health may help preserve cognitive functions in PD.

Nicotine Has a Therapeutic Window of Effectiveness in a Drosophila melanogaster Model of Parkinson’s Disease

Strong epidemiological evidence and studies in models of Parkinson's disease (PD) suggest that nicotine may be therapeutically beneficial in PD patients. However, a number of clinical trials utilizing nicotine in PD patients have had mixed results, indicating that either nicotine is not beneficial in PD patients, or an important aspect of nicotine therapy was absent. We hypothesized that nicotine must be administered early in the adult fly life in order to have beneficial effects. We show that continuous early nicotine administration improves both climbing and flight deficiencies present in homozygous park²⁵ mutant PD model Drosophila melanogaster. Using a new climbing assay, we identify several climbing deficiencies in this PD model that are improved or rescued by continuous nicotine treatment. Amongst these benefits, it appears that nicotine improves the ability of the park²⁵ flies to descend the climbing vial by being able to climb down more. In support of our hypothesis, we show that in order for nicotine benefits on climbing and flight to happen, nicotine administration must occur in a discrete time frame following adult fly eclosure: within one day for climbing or five days for flight. This therapeutic window of nicotine administration in this PD model fly may help to explain the lack of efficacy of nicotine in human clinical trials.

Nicotine in Inflammatory Diseases: Anti-Inflammatory and Pro-Inflammatory Effects

As an anti-inflammatory alkaloid, nicotine plays dual roles in treating diseases. Here we reviewed the anti-inflammatory and pro-inflammatory effects of nicotine on inflammatory diseases, including inflammatory bowel disease, arthritis, multiple sclerosis, sepsis, endotoxemia, myocarditis, oral/skin/muscle inflammation, etc., mainly concerning the administration methods, different models, therapeutic concentration and duration, and relevant organs and tissues. According to the data analysis from recent studies in the past 20 years, nicotine exerts much more anti-inflammatory effects than pro-inflammatory ones, especially in ulcerative colitis, arthritis, sepsis, and endotoxemia. On the other hand, in oral inflammation, nicotine promotes and aggravates some diseases such as periodontitis and gingivitis, especially when there are harmful microorganisms in the oral cavity. We also carefully analyzed the nicotine dosage to determine its safe and effective range. Furthermore, we summarized the molecular mechanism of nicotine in these inflammatory diseases through regulating immune cells, immune factors, and the vagus and acetylcholinergic anti-inflammatory pathways. By balancing the “beneficial” and “harmful” effects of nicotine, it is meaningful to explore the effective medical value of nicotine and open up new horizons for remedying acute and chronic inflammation in humans.

The impact of cigarette smoking and nicotine on traumatic brain injury: a review

INTRODUCTION

Traumatic Brain Injury (TBI) and tobacco smoking are both serious public health problems. Many people with TBI also smoke. Nicotine, a component of tobacco smoke, has been identified as a premorbid neuroprotectant in other neurological disorders. This study aims to provide better understanding of relationships between tobacco smoking and nicotine use and effect on outcome/recovery from TBI.

METHODS

PubMed database, SCOPUS, and PTSDpub were searched for relevant English-language papers.

RESULTS

Twenty-nine human clinical studies and nine animal studies were included. No nicotine-replacement product use in human TBI clinical studies were identified. While smoking tobacco prior to injury can be harmful primarily due to systemic effects that can compromise brain function, animal studies suggest that nicotine as a pharmacological agent may augment recovery of cognitive deficits caused by TBI.

CONCLUSIONS

While tobacco smoking before or after TBI has been associated with potential harms, many clinical studies downplay correlations for most expected domains. On the other hand, nicotine could provide potential treatment for cognitive deficits following TBI by reversing impaired signaling pathways in the brain including those involving nAChRs, TH, and dopamine. Future studies regarding the impact of cigarette smoking and vaping on patients with TBI are needed .

Emerging roles of NAC transcription factor in medicinal plants: progress and prospects

Transcriptional factors act as mediators in regulating stress response in plants from signal perception to processing the directed gene expression. WRKY, MYB, AP2/ERF, etc. are some of the major families of transcription factors known to mediate stress mechanisms in plants by regulating the production of secondary metabolites. NAC domain-containing proteins are among these large transcription factors families in plants. These proteins play impulsive roles in plant growth, development, and various abiotic as well as biotic stresses. They are involved in regulating the different signaling pathways of plant hormones that direct a plant's immunity against pathogens, thereby affecting their immune responses. However, their role in stress regulation or defence mechanism in plants through the secondary metabolite biosynthesis pathway is studied for very few cases. Emerging concern over the requirement of medicinal plants for the production of biocompatible drugs and antibiotics, the study of these vast, affecting proteins should be focused to improve their qualitative and quantitative production further. In medicinal plants, phytochemicals and secondary metabolites are the major biochemicals that impose antimicrobial and other medicinal properties in these plants. This review compiles the NAC transcription factors reported in selected medicinal plants and their possible roles in different mechanisms. Further, the comprehensive understanding of the molecular mechanism, genetic engineering, and regulation responses of NAC TFs in medicinal plants, can lead to improvement in stress response, immunity, and production of usable secondary metabolites.

Regulators of cholinergic signaling in disorders of the central nervous system

Cholinergic signaling is crucial in cognitive processes, and degenerating cholinergic projections are a pathological hallmark in dementia. Use of cholinesterase inhibitors is currently the main treatment option to alleviate symptoms of Alzheimer's disease and has been postulated as a therapeutic strategy in acute brain damage (stroke and traumatic brain injury). However, the benefits of this treatment are still not clear. Importantly, cholinergic receptors are expressed both by neurons and by astrocytes and microglia, and binding of acetylcholine to the α7 nicotinic receptor in glial cells results in anti-inflammatory response. Similarly, the brain fine-tunes the peripheral immune response over the cholinergic anti-inflammatory axis. All of these processes are of importance for the outcome of acute and chronic neurological disease. Here, we summarize the main findings about the role of cholinergic signaling in brain disorders and provide insights into the complexity of molecular regulators of cholinergic responses, such as microRNAs and transfer RNA fragments, both of which may fine-tune the orchestra of cholinergic mRNAs. The available data suggest that these small noncoding RNA regulators may include promising biomarkers for predicting disease course and assessing treatment responses and might also serve as drug targets to attenuate signaling cascades during overwhelming inflammation and to ameliorate regenerative capacities of neuroinflammation.

Recent advances in the pathology of prodromal non-motor symptoms olfactory deficit and depression in Parkinson's disease: clues to early diagnosis and effective treatment

Parkinson’s disease (PD) is a progressive neurodegenerative disease characterized by movement dysfunction due to selective degeneration of dopaminergic neurons in the substantia nigra pars compacta. Non-motor symptoms of PD (e.g., sensory dysfunction, sleep disturbance, constipation, neuropsychiatric symptoms) precede motor symptoms, appear at all stages, and impact the quality of life, but they frequently go unrecognized and remain untreated. Even when identified, traditional dopamine replacement therapies have little effect. We discuss here the pathology of two PD-associated non-motor symptoms: olfactory dysfunction and depression. Olfactory dysfunction is one of the earliest non-motor symptoms in PD and predates the onset of motor symptoms. It is accompanied by early deposition of Lewy pathology and neurotransmitter alterations. Because of the correlation between olfactory dysfunction and an increased risk of progression to PD, olfactory testing can potentially be a specific diagnostic marker of PD in the prodromal stage. Depression is a prevalent PD-associated symptom and is often associated with reduced quality of life. Although the pathophysiology of depression in PD is unclear, studies suggest a causal relationship with abnormal neurotransmission and abnormal adult neurogenesis. Here, we summarize recent progress in the pathology of the non-motor symptoms of PD, aiming to provide better guidance for its effective management.

Central Pain in Parkinson's Disease: Behavioral and Cognitive Characteristics

Introduction

Pain is a major nonmotor symptom of Parkinson's disease (PD), and central parkinsonian pain is the core feature of the putative Park pain subtype of PD. This study aimed to explore the cognitive and behavioral profile of PD patients with central parkinsonian pain. Material and Methods. A structured interview was used to identify and characterize pain in a cohort of 260 consecutive PD patients. The Ford classification of pain was applied. The Dementia Rating Scale-2 (DRS-2) and the Impulse Control Disorders in Parkinson's Disease Short Form (QUIP-S) were administered, and patients' smoking habits were recorded. The Unified Parkinson's Disease Rating Scale (UPDRS) was used to assess motor and nonmotor symptoms in off and on conditions.

Results

One hundred and eighty-eight patients (68%) reported pain; and in 41 (22%) of them, the pain was classified as central parkinsonian pain. PD patients with central parkinsonian pain had better cognitive performance in DRS-2 Initiation/Perseveration and Conceptualization subscales but reported more other compulsive behaviors (e.g., hobbyism, punding, and walkabout) and had more current smoking habits than those without pain or with non-central parkinsonian pain. Multiple logistic regression analyses revealed that the DRS-2 Conceptualization subscale, other compulsive behaviors, and smoking habits remained statistically associated with central parkinsonian pain even when other significant covariates were considered. Only patients with pain, regardless of type, had a gambling disorder. Discussion. The study results provide further evidence that pain revealed that patients with central parkinsonian pain are more likely to present compulsive or addictive behaviors, despite having more preserved cognitive performance. Patients with central parkinsonian pain appear to have a distinct phenotype of PD.

Molecular insights into the benefits of nicotine on memory and cognition (Review)

The health risks of nicotine are well known, but there is some evidence of its beneficial effects on cognitive function. The present review focused on the reported benefits of nicotine in the brain and summarizes the associated underlying mechanisms. Nicotine administration can improve cognitive impairment in Alzheimer's disease (AD), and dyskinesia and memory impairment in Parkinson's disease (PD). In terms of its mechanism of action, nicotine slows the progression of PD by inhibiting Sirtuin 6, a stress‑responsive protein deacetylase, thereby decreasing neuronal apoptosis and improving neuronal survival. In AD, nicotine improves cognitive impairment by enhancing protein kinase B (also referred to as Akt) activity and stimulating phosphoinositide 3‑kinase/Akt signaling, which regulates learning and memory processes. Nicotine may also activate thyroid receptor signaling pathways to improve memory impairment caused by hypothyroidism. In healthy individuals, nicotine improves memory impairment caused by sleep deprivation by enhancing the phosphorylation of calmodulin‑dependent protein kinase II, an essential regulator of cell proliferation and synaptic plasticity. Furthermore, nicotine may improve memory function through its effect on chromatin modification via the inhibition of histone deacetylases, which causes transcriptional changes in memory‑related genes. Finally, nicotine administration has been demonstrated to rescue long‑term potentiation in individuals with sleep deprivation, AD, chronic stress and hypothyroidism, primarily by desensitizing α7 nicotinic acetylcholine receptors. To conclude, nicotine has several cognitive benefits in healthy individuals, as well as in those with cognitive dysfunction associated with various diseases. However, further research is required to shed light on the effect of acute and chronic nicotine treatment on memory function.

Nicotine suppresses Parkinson's disease like phenotypes induced by Synphilin-1 overexpression in Drosophila melanogaster by increasing tyrosine hydroxylase and dopamine levels

It has been observed that there is a lower Parkinson's disease (PD) incidence in tobacco users. Nicotine is a cholinergic agonist and is the principal psychoactive compound in tobacco linked to cigarette addiction. Different studies have shown that nicotine has beneficial effects on sporadic and genetic models of PD. In this work we evaluate nicotine's protective effect in a Drosophila melanogaster model for PD where Synphilin-1 (Sph-1) is expressed in dopaminergic neurons. Nicotine has a moderate effect on dopaminergic neuron survival that becomes more evident as flies age. Nicotine is beneficial on fly survival and motility increasing tyrosine hydroxylase and dopamine levels, suggesting that cholinergic agonists may promote survival and metabolic function of the dopaminergic neurons that express Sph-1. The Sph-1 expressing fly is a good model for the study of early-onset phenotypes such as olfaction loss one of the main non-motor symptom related to PD. Our data suggest that nicotine is an interesting therapeutic molecule whose properties should be explored in future research on the phenotypic modulators of the disease and for the development of new treatments.

Nicotine induces morphological and functional changes in astrocytes via nicotinic receptor activity

Nicotine is a highly addictive compound present in tobacco, which causes the release of dopamine in different regions of the brain. Recent studies have shown that astrocytes express nicotinic acetylcholine receptors (nAChRs) and mediate calcium signaling. In this study, we examine the morphological and functional adaptations of astrocytes due to nicotine exposure. Utilizing a combination of fluorescence and atomic force microscopy, we show that nicotine-treated astrocytes exhibit time-dependent remodeling in the number and length of both proximal and fine processes. Blocking nAChR activity with an antagonist completely abolishes nicotine's influence on astrocyte morphology indicating that nicotine's action is mediated by these receptors. Functional studies show that 24-hr nicotine treatment induces higher levels of calcium activity in both the cell soma and the processes with a more substantial change observed in the processes. Nicotine does not induce reactive astrocytosis even at high concentrations (10 μM) as determined by cytokine release and glial fibrillary acidic protein expression. We designed tissue clearing experiments to test whether morphological changes occur in vivo using astrocyte specific Aldh1l1-tdTomato knock in mice. We find that nicotine induces a change in the volume of astrocytes in the prefrontal cortex, CA1 of the hippocampus, and the substantia nigra. These results indicate that nicotine directly alters the functional and morphological properties of astrocytes potentially contributing to the underlying mechanism of nicotine abuse.

Allosterism of Nicotinic Acetylcholine Receptors: Therapeutic Potential for Neuroinflammation Underlying Brain Trauma and Degenerative Disorders

Inflammation is a key physiological phenomenon that can be pervasive when dysregulated. Persistent chronic inflammation precedes several pathophysiological conditions forming one of the critical cellular homeostatic checkpoints. With a steady global surge in inflammatory diseases, it is imperative to delineate underlying mechanisms and design suitable drug molecules targeting the cellular partners that mediate and regulate inflammation. Nicotinic acetylcholine receptors have a confirmed role in influencing inflammatory pathways and have been a subject of scientific scrutiny underlying drug development in recent years. Drugs designed to target allosteric sites on the nicotinic acetylcholine receptors present a unique opportunity to unravel the role of the cholinergic system in regulating and restoring inflammatory homeostasis. Such a therapeutic approach holds promise in treating several inflammatory conditions and diseases with inflammation as an underlying pathology. Here, we briefly describe the potential of cholinergic allosterism and some allosteric modulators as a promising therapeutic option for the treatment of neuroinflammation.

Calcium-Handling Defects and Neurodegenerative Disease

Calcium signaling is critical to neuronal function and regulates highly diverse processes such as gene transcription, energy production, protein handling, and synaptic structure and function. Because there are many common underlying calcium-mediated pathological features observed across several neurological conditions, it has been proposed that neurodegenerative diseases have an upstream underlying calcium basis in their pathogenesis. With certain diseases such as Alzheimer's, Parkinson's, and Huntington's, specific sources of calcium dysregulation originating from distinct neuronal compartments or channels have been shown to have defined roles in initiating or sustaining disease mechanisms. Herein, we will review the major hallmarks of these diseases, and how they relate to calcium dysregulation. We will then discuss neuronal calcium handling throughout the neuron, with special emphasis on channels involved in neurodegeneration.

Co-occurring WARS2 and CHRNA6 mutations in a child with a severe form of infantile parkinsonism

OBJECTIVE

To investigate the molecular cause(s) underlying a severe form of infantile-onset parkinsonism and characterize functionally the identified variants.

METHODS

A trio-based whole exome sequencing (WES) approach was used to identify the candidate variants underlying the disorder. In silico modeling, and in vitro and in vivo studies were performed to explore the impact of these variants on protein function and relevant cellular processes.

RESULTS

WES analysis identified biallelic variants in WARS2, encoding the mitochondrial tryptophanyl tRNA synthetase (mtTrpRS), a gene whose mutations have recently been associated with multiple neurological phenotypes, including childhood-onset, levodopa-responsive or unresponsive parkinsonism in a few patients. A substantial reduction of mtTrpRS levels in mitochondria and reduced OXPHOS function was demonstrated, supporting their pathogenicity. Based on the infantile-onset and severity of the phenotype, additional variants were considered as possible genetic modifiers. Functional assessment of a selected panel of candidates pointed to a de novo missense mutation in CHRNA6, encoding the α6 subunit of neuronal nicotinic receptors, which are involved in the cholinergic modulation of dopamine release in the striatum, as a second event likely contributing to the phenotype. In silico, in vitro (Xenopus oocytes and GH4C1 cells) and in vivo (C. elegans) analyses demonstrated the disruptive effects of the mutation on acetylcholine receptor structure and function.

CONCLUSION

Our findings consolidate the association between biallelic WARS2 mutations and movement disorders, and suggest CHRNA6 as a genetic modifier of the phenotype.

Machine Learning Neuroprotective Strategy Reveals a Unique Set of Parkinson Therapeutic Nicotine Analogs

AIMS

Present a novel machine learning computational strategy to predict the neuroprotection potential of nicotine analogs acting over the behavior of unpaired signaling pathways in Parkinson's disease.

BACKGROUND

Dopaminergic replacement has been used for Parkinson's Disease (PD) treatment with positive effects on motor symptomatology but low progression and prevention effects. Epidemiological studies have shown that nicotine consumption decreases PD prevalence through neuroprotective mechanisms activation associated with the overstimulation of signaling pathways (SP) such as PI3K/AKT through nicotinic acetylcholine receptors (e.g α7 nAChRs) and over-expression of anti-apoptotic genes such as Bcl-2. Nicotine analogs with similar neuroprotective activity but decreased secondary effects remain as a promissory field.

OBJECTIVE

The objective of this study is to develop an interdisciplinary computational strategy predicting the neuroprotective activity of a series of 8 novel nicotine analogs over Parkinson's disease.

METHODS

We present a computational strategy integrating structural bioinformatics, SP manual reconstruction, and deep learning to predict the potential neuroprotective activity of 8 novel nicotine analogs over the behavior of PI3K/AKT. We performed a protein-ligand analysis between nicotine analogs and α7 nAChRs receptor using geometrical conformers, physicochemical characterization of the analogs and developed manually curated neuroprotective datasets to analyze their potential activity. Additionally, we developed a predictive machine-learning model for neuroprotection in PD through the integration of Markov Chain Monte-Carlo transition matrix for the 2 SP with synthetic training datasets of the physicochemical properties and structural dataset.

RESULTS

Our model was able to predict the potential neuroprotective activity of seven new nicotine analogs based on the binomial Bcl-2 response regulated by the activation of PI3K/AKT.

CONCLUSION

Hereby, we present a robust novel strategy to assess the neuroprotective potential of biomolecules based on SP architecture. Our theoretical strategy can be further applied to the study of new treatments related to SP deregulation and may ultimately offer new opportunities for therapeutic interventions in neurodegenerative diseases.

The Drosophila Model: Exploring Novel Therapeutic Compounds against Neurodegenerative Diseases

Polyphenols are secondary metabolites of plants, fruits, and vegetables. They act as antioxidants against free radicals from UV light, pathogens, parasites, and oxidative stress. In Drosophila models, feeding with various polyphenols results in increased antioxidant capacity and prolonged lifespan. Therefore, dietary polyphenols have several health advantages for preventing many human diseases, including cardiovascular diseases, cancer, and neurodegenerative diseases. However, the exact role of polyphenols in neurodegenerative diseases is still yet to be completely defined. This review focuses on the most recent studies related to the therapeutic effect of polyphenols in neurodegenerative disease management and provides an overview of novel drug discovery from various polyphenols using the Drosophila model.

Activation of α7-nAChRs protects SH-SY5Y cells from 1-methyl-4-phenylpyridinium-induced apoptotic cell death via ERK/p53 signaling pathway

Epidemiologic studies have shown a reduced risk of developing Parkinson's disease (PD) among cigarette smokers. Nicotine, as a key component in tobacco products, is thought as a possible candidate for action of smoking in neuroprotection. α7 nicotinic acetylcholine receptors (α7-nAChRs) is one of the most abundant nAChRs in the mammalian brain. Although nicotine is thought to exert this protective action by acting on nicotinic receptors, including the α7-nAChRs; the mechanisms underlying how α7-nAChRs protect against dopaminergic neuron loss are highly complex. Using nicotine and a selective α7-nAChR agonist PNU-282987, we first confirmed that their addition to SH-SY5Y cells challenged with 1-methyl-4-phenylpyridinium (MPP⁺ ) could afford neuroprotection and result in a reduction in apoptotic cell death. Then, we found that the pretreatment with nicotine and PNU-282987 showed the neuroprotective antiapoptotic effects via activating the α7-nAChRs/MAPK/p53 axis. Furthermore, we used RNA interference to silence the expression of α7-nAChRs in SH-SY5Y cells and found that suppressing α7-nAChR expression diminished the antiapoptotic effects of nicotine and PNU-282987, not the toxic effects of MPP⁺ . Moreover, α7-nAChR knockdown could only decrease the inhibitory effects of nicotine and PNU-282987 on the phosphorylated extracellular signal-regulated kinase (ERK), not c-Jun amino-terminal kinase and p38. Therefore, our findings indicate the important roles of ERK/MAPK signaling in the neuroprotective effects of α7-nAChRs and suggest that α7-nAChR agonists may be validated as novel treatments for PD.

Nicotinic Acetylcholine Receptor Ligands, Cognitive Function, and Preclinical Approaches to Drug Discovery

Interest in nicotinic acetylcholine receptor (nAChR) ligands as potential therapeutic agents for cognitive disorders began more than 30 years ago when it was first demonstrated that the tobacco alkaloid nicotine could improve cognitive function in nicotine-deprived smokers as well as nonsmokers. Numerous animal and human studies now indicate that nicotine and a variety of nAChR ligands have the potential to improve multiple domains of cognition including attention, spatial learning, working memory, recognition memory, and executive function. The purpose of this review is to (1) discuss several pharmacologic strategies that have been developed to enhance nAChR activity (eg, agonist, partial agonist, and positive allosteric modulator) and improve cognitive function, (2) provide a brief overview of some of the more common rodent behavioral tasks with established translational validity that have been used to evaluate nAChR ligands for effects on cognitive function, and (3) briefly discuss some of the topics of debate regarding the development of optimal therapeutic strategies using nAChR ligands. Because of their densities in the mammalian brain and the amount of literature available, the review primarily focuses on ligands of the high-affinity α4β2* nAChR ("*" indicates the possible presence of additional subunits in the complex) and the low-affinity α7 nAChR. The behavioral task discussion focuses on representative methods that have been designed to model specific domains of cognition that are relevant to human neuropsychiatric disorders and often evaluated in human clinical trials.

IMPLICATIONS

The preclinical literature continues to grow in support of the development of nAChR ligands for a variety of illnesses that affect humans. However, to date, no new nAChR ligand has been approved for any condition other than nicotine dependence. As discussed in this review, the studies conducted to date provide the impetus for continuing efforts to develop new nAChR strategies (ie, beyond simple agonist and partial agonist approaches) as well as to refine current behavioral strategies and create new animal models to address translational gaps in the drug discovery process.

Aldehyde adducts inhibit 3,4-dihydroxyphenylacetaldehyde-induced α-synuclein aggregation and toxicity: Implication for Parkinson neuroprotective therapy

3,4-Dihydroxyphenylacetaldehyde (DOPAL), the monoamine oxidase (MAO) metabolite of dopamine, plays a role in pathogenesis of Parkinson disease, inducing α-synuclein aggregation. DOPAL generates discrete α-synuclein aggregates. Inhibiting this aggregation could provide therapy for slowing Parkinson disease progression. Primary and secondary amines form adducts with aldehydes. Rasagiline and aminoindan contain these amine groups. DOPAL-induced α-synuclein aggregates were resolved in the presence and absence of rasagiline or aminoindan using quantitative Western blotting. DOPAL levels in incubation mixtures, containing increased rasagiline or aminoindan concentrations, were determined by high pressure liquid chromatography (HPLC). Schiff base adducts between DOPAL and rasagiline or aminoindan were determined using mass spectrometry. A neuroprotective effect of rasagiline and aminoindan against DOPAL-induced toxicity was demonstrated using PC-12 cells. Rasagiline and aminoindan significantly reduced aggregation of α-synuclein of all sizes in test tube and PC-12 cells experiments. Dimethylaminoindan did not reduce aggregation. DOPAL levels in incubation mixtures were reduced with increasing rasagiline or aminoindan concentrations but not with dimethylaminoindan. Schiff base adducts between DOPAL and either rasagiline or aminoindan were demonstrated by mass spectrometry. A neuroprotective effect against DOPAL-induced toxicity in PC-12 cells was demonstrated for both rasagiline and aminoindan. Inhibiting DOPAL-induced α-synuclein aggregation through amine adducts provides a therapeutic approach for slowing Parkinson disease progression.

Effects of overexpression of jasmonic acid biosynthesis genes on nicotine accumulation in tobacco

Nicotine is naturally synthesized in tobacco roots and accumulates in leaves as a defense compound against herbivory attack. Nicotine biosynthesis pathway has been extensively studied with major genes and enzymes being isolated and functionally characterized. However, the molecular regulation of nicotine synthesis has not been fully understood. The phytohormone jasmonic acid (JA) mediates many aspects of plant defense responses including nicotine biosynthesis. In this study, five key genes (AtLOX2, AtAOS, AtAOC2, AtOPR3, AtJAR1) involved in JA biosynthesis from Arabidopsis were individually overexpressed, and a JA-Ile hydrolysis-related gene, NtJIH1, was suppressed by RNAi approach, to understand their effects on nicotine accumulation in tobacco. Interestingly, while transgene expression was high, levels of JA-Ile (the biologically active form of JA) were often significantly reduced. Meanwhile, nicotine content in these transgenic plants did not increase. The research revealed a tightly controlled JA signaling pathway and a complicated regulatory network for nicotine biosynthesis by JA signaling.

Revisiting nicotine’s role in the ageing brain and cognitive impairment

Brain ageing is a complex process which in its pathologic form is associated with learning and memory dysfunction or cognitive impairment. During ageing, changes in cholinergic innervations and reduced acetylcholinergic tonus may trigger a series of molecular pathways participating in oxidative stress, excitotoxicity, amyloid-β toxicity, apoptosis, neuroinflammation, and perturb neurotrophic factors in the brain. Nicotine is an exogenous agonist of nicotinic acetylcholine receptors (nAChRs) and acts as a pharmacological chaperone in the regulation of nAChR expression, potentially intervening in age-related changes in diverse molecular pathways leading to pathology. Although nicotine has therapeutic potential, paradoxical effects have been reported, possibly due to its inverted U-shape dose-response effects or pharmacokinetic factors. Additionally, nicotine administration should result in optimum therapeutic effects without imparting abuse potential or toxicity. Overall, this review aims to compile the previous and most recent data on nicotine and its effects on cognition-related mechanisms and age-related cognitive impairment.

Nicotine from cigarette smoking and diet and Parkinson disease: a review

Evidence from epidemiological studies suggest a relationship between cigarette smoking and low risk of Parkinson disease (PD). As a major component of tobacco smoke, nicotine has been proposed to be a substance for preventing against PD risk, with a key role in regulating striatal activity and behaviors mediated through the dopaminergic system. Animal studies also showed that nicotine could modulate dopamine transmission and reduce levodopa-induced dyskinesias. However, previous clinical trials yield controversial results regarding nicotine treatment. In this review, we updated epidemiological, preclinical and clinical data, and studies on nicotine from diet. We also reviewed interactions between genetic factors and cigarette smoking. As a small amount of nicotine can saturate a substantial portion of nicotine receptors in the brain, nicotine from other sources, such as diet, could be a promising therapeutic substance for protection against PD.

Recent advances in treating Parkinson's disease

This article summarizes (1) the recent achievements to further improve symptomatic therapy of motor Parkinson’s disease (PD) symptoms, (2) the still-few attempts to systematically search for symptomatic therapy of non-motor symptoms in PD, and (3) the advances in the development and clinical testing of compounds which promise to offer disease modification in already-manifest PD. However, prevention (that is, slowing or stopping PD in a prodromal stage) is still a dream and one reason for this is that we have no consensus on primary endpoints for clinical trials which reflect the progression in prodromal stages of PD, such as in rapid eye movement sleep behavior disorder (RBD) —a methodological challenge to be met in the future.

Drug-Induced Dyskinesia, Part 1: Treatment of Levodopa-Induced Dyskinesia

Dyskinesias encompass a variety of different hyperkinetic phenomenologies, particularly chorea, dystonia, stereotypies, and akathisia. Levodopa-induced dyskinesia (LID) is one of the main types of drug-induced dyskinesia, occurring in patients with Parkinson's disease (PD) who have been treated with levodopa for long time, but this side effect may be encountered even within a few weeks or months after initiation of levodopa therapy. Based on the temporal pattern in relationship to levodopa dosing, LIDs are divided into "peak-dose dyskinesia," "diphasic dyskinesia," and "wearing off" or "off-period" dyskinesia, of which peak-dose dyskinesia is the most common, followed by off-period, and then diphasic dyskinesia. Treatment strategy includes identifying the kind of dyskinesia and tailoring treatment accordingly. Peak-dose dyskinesia is treated mainly by reducing individual doses of levodopa and adding amantadine and dopamine agonists, whereas off-period dystonia often responds to baclofen and botulinum toxin injections. Diphasic dyskinesias, occurring particularly in patients with young-onset PD, are the most difficult to treat. While fractionation of levodopa dosage is the most frequently utilized strategy, many patients require deep brain stimulation to control their troublesome motor fluctuations and LIDs. A variety of emerging (experimental) drugs currently in development promise to provide better control of LIDs and other levodopa-related complications in the near future.

Optogenetic activation of striatal cholinergic interneurons regulates L-dopa-induced dyskinesias

L-dopa-induced dyskinesias (LIDs) are a serious complication of L-dopa therapy for Parkinson's disease. Emerging evidence indicates that the nicotinic cholinergic system plays a role in LIDs, although the pathways and mechanisms are poorly understood. Here we used optogenetics to investigate the role of striatal cholinergic interneurons in LIDs. Mice expressing cre-recombinase under the control of the choline acetyltransferase promoter (ChAT-Cre) were lesioned by unilateral injection of 6-hydroxydopamine. AAV5-ChR2-eYFP or AAV5-control-eYFP was injected into the dorsolateral striatum, and optical fibers implanted. After stable virus expression, mice were treated with L-dopa. They were then subjected to various stimulation protocols for 2h and LIDs rated. Continuous stimulation with a short duration optical pulse (1-5ms) enhanced LIDs. This effect was blocked by the general muscarinic acetylcholine receptor (mAChR) antagonist atropine indicating it was mAChR-mediated. By contrast, continuous stimulation with a longer duration optical pulse (20ms to 1s) reduced LIDs to a similar extent as nicotine treatment (~50%). The general nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine blocked the decline in LIDs with longer optical pulses showing it was nAChR-mediated. None of the stimulation regimens altered LIDs in control-eYFP mice. Lesion-induced motor impairment was not affected by optical stimulation indicating that cholinergic transmission selectively regulates LIDs. Longer pulse stimulation increased the number of c-Fos expressing ChAT neurons, suggesting that changes in this immediate early gene may be involved. These results demonstrate that striatal cholinergic interneurons play a critical role in LIDs and support the idea that nicotine treatment reduces LIDs via nAChR desensitization.

Genetic Factors for Enhancement of Nicotine Levels in Cultivated Tobacco

Nicotine has practical applications relating to smoking cessation devices and alternative nicotine products. Genetic manipulation for increasing nicotine content in cultivated tobacco (Nicotiana tabacum L.) may be of value for industrial purposes, including the possibility of enhancing the efficiency of nicotine extraction. Biotechnological approaches have been evaluated in connection with this objective, but field-based results are few. Here, we report characterization of two genes encoding basic-helix-loop-helix (bHLH) transcription factors (TFs), NtMYC2a and NtMYC2b from tobacco. Overexpression of NtMYC2a increased leaf nicotine levels in T1 transgenic lines approximately 2.3-fold in greenhouse-grown plants of tobacco cultivar 'NC 95'. Subsequent field testing of T2 and T3 generations of transgenic NtMYC2a overexpression lines showed nicotine concentrations were 76% and 58% higher than control lines, respectively. These results demonstrated that the increased nicotine trait was stably inherited to the T2 and T3 generations, indicating the important role that NtMYC2a plays in regulating nicotine accumulation in N. tabacum and the great potential of NtMYC2a overexpression in tobacco plants for industrial nicotine production. Collected data in this study also indicated a negative feedback inhibition of nicotine biosynthesis. Further enhancement of nicotine accumulation in tobacco leaf may require modification of the processes of nicotine transport and deposition.

Smoking and outcome of traumatic brain injury

OBJECTIVE

There is evidence that the cholinergic system is involved in cognitive sequels of traumatic brain injury (TBI). Nicotinic acetylcholine receptors (nAChRs) are known to have a major role in cognitive functions. Smokers have up-regulation of these receptors. This study investigated whether smoking is associated with the outcome from TBI.

METHODS

A specific questionnaire was sent, after checking inclusion and exclusion criteria, to 1022 subjects with TBI who had visited the neurological outpatient clinic of a university hospital during a 14-year period. Of these, 689 (67.4%) responded, forming the final study population. Associations between demographic variables, injury severity and outcome and smoking history were analysed using multivariate methods.

RESULTS

Smokers were more often men (p < 0.001), younger at the time of the injury (p = 0.008) and had less education (p < 0.0001). In univariate analysis, non-smokers did not differ for outcome of TBI by GOS-E (p = 0.08). Furthermore, in multivariate analysis, no association was found between smoking history and TBI outcome.

CONCLUSIONS

This study does not suggest that smoking affects the outcome of TBI.

Where attention falls: Increased risk of falls from the converging impact of cortical cholinergic and midbrain dopamine loss on striatal function

Falls are a major source of hospitalization, long-term institutionalization, and death in older adults and patients with Parkinson's disease (PD). Limited attentional resources are a major risk factor for falls. In this review, we specify cognitive-behavioral mechanisms that produce falls and map these mechanisms onto a model of multi-system degeneration. Results from PET studies in PD fallers and findings from a recently developed animal model support the hypothesis that falls result from interactions between loss of basal forebrain cholinergic projections to the cortex and striatal dopamine loss. Striatal dopamine loss produces inefficient, low-vigor gait, posture control, and movement. Cortical cholinergic deafferentation impairs a wide range of attentional processes, including monitoring of gait, posture and complex movements. Cholinergic cell loss reveals the full impact of striatal dopamine loss on motor performance, reflecting loss of compensatory attentional supervision of movement. Dysregulation of dorsomedial striatal circuitry is an essential, albeit not exclusive, mediator of falls in this dual-system model. Because cholinergic neuromodulatory activity influences cortical circuitry primarily via stimulation of α4β2* nicotinic acetylcholine receptors, and because agonists at these receptors are known to benefit attentional processes in animals and humans, treating PD fallers with such agonists, as an adjunct to dopaminergic treatment, is predicted to reduce falls. Falls are an informative behavioral endpoint to study attentional-motor integration by striatal circuitry.

A case-control study of the protective effect of alcohol, coffee, and cigarette consumption on Parkinson disease risk: time-since-cessation modifies the effect of tobacco smoking

The aim of this study was to investigate the possible reduced risk of Parkinson Disease (PD) due to coffee, alcohol, and/or cigarette consumption. In addition, we explored the potential effect modification by intensity, duration and time-since-cessation of smoking on the association between cumulative pack-years of cigarette smoking (total smoking) and PD risk. Data of a hospital based case-control study was used including 444 PD patients, diagnosed between 2006 and 2011, and 876 matched controls from 5 hospitals in the Netherlands. A novel modeling method was applied to derive unbiased estimates of the potential modifying effects of smoking intensity, duration, and time-since-cessation by conditioning on total exposure. We observed no reduced risk of PD by alcohol consumption and only a weak inverse association between coffee consumption and PD risk. However, a strong inverse association of total smoking with PD risk was observed (OR=0.27 (95%CI: 0.18-0.42) for never smokers versus highest quartile of tobacco use). The observed protective effect of total smoking was significantly modified by time-since-cessation with a diminishing protective effect after cessation of smoking. No effect modification by intensity or duration of smoking was observed indicating that both intensity and duration have an equal contribution to the reduced PD risk. Understanding the dynamics of the protective effect of smoking on PD risk aids in understanding PD etiology and may contribute to strategies for prevention and treatment.

CHRNB3 c.-57A>G functional promoter change affects Parkinson's disease and smoking

Cigarette smoking is protective in Parkinson's disease (PD), possibly because of nicotine action on brain nicotinic-acetylcholine receptors. The β3 nicotinic-acetylcholine receptor subunit (encoded by CHRNB3) is depleted in the striatum of PD patients and associated with nicotine dependence. Herein, the CHRNB3 gene was sequenced, and the c.-57G allele frequency was 0.31 and 0.26 among patients (n = 596) and controls (n = 369), respectively (p = 0.02, odds ratio = 1.33, 95% confidence interval = 1.03-1.73). The c.-57G allele was strongly associated with smoking in patients, as 48.4% of c.-57G carriers compared with 32.6% of noncarriers reported smoking history (p < 0.0001). The transcription factor Oct-1 binding was almost eliminated in lymphoblasts with the c.-57G/G genotype, to only 6.5% percent, and the CHRNB3 promoter activity was reduced in cells with the c.-57G/G genotype by 96%-70%. These findings suggest that the CHRNB3 c.-57A>G alteration affects the promoter activity and is associated with PD and smoking in PD patients. It is therefore possible that nicotine may be valuable for patients who carry this alteration and beneficial in PD only for patients with specific genotypes.