Dopamine dysregulation syndrome, addiction and behavioral changes in Parkinson's disease

Optical sensing of L-dihydroxy-phenylalanine in water by a high-affinity molecular receptor involving cooperative binding of a metal coordination bond and boronate-diol

Selective recognition and sensing of catecholamine-based neurotransmitters by fluorescent synthetic receptors capable of operating in pure water is a central topic of modern supramolecular chemistry that impacts biological and analytical chemistry. Despite advances achieved in the recognition of some neurotransmitters such as dopamine, little effort has been invested in the optical recognition of other neurotransmitters of paramount importance in biochemistry and medicinal chemistry such as the drug L-dihydroxy-phenylalanine (levodopa). Herein, a cationic Cu(II)-terpyridine complex bearing an intramolecular fluorescent quinolinium ring covalently linked to phenylboronic acid (CuL1) was synthesized, structurally described by single-crystal X-ray diffraction and studied in-depth as a fluorescent receptor for neurotransmitters in water. The complex CuL1 was designed to act as a receptor for levodopa through two Lewis acids of different natures (Cu(II) and B atoms) as cooperative binding points. The receptor CuL1 was found to have a strongly acidified -B(OH)2 group (pKa = 6.2) and exceptionally high affinity for levodopa (K = 4.8 × 106 M-1) with selectivity over other related neurotransmitters such as dopamine, epinephrine, norepinephrine and nucleosides in the micromolar concentration range at physiological pH. Such levodopa affinity/selectivity for a boronic acid-based receptor in water is still rare. On the basis of spectroscopic tools (11B NMR, UV-vis, EPR, and fluorescence), high-resolution ESI-MS, crystal structure, and DFT calculations, the interaction mode of CuL1 with levodopa is proposed in a 1 : 1 model using two-point recognition involving a boronate-catechol esterification and a coordination bond Cu(II)-carboxylate. Furthermore, a visual sensing ensemble was constructed using CuL1 and the commercial fluorescent dye eosin Y. Levodopa is efficiently detected by the displacement of the eosin Y bound to the Cu(II)-receptor, monitoring its green emission. The use of Cu(II)-boronate complexes for fast and selective neurotransmitter sensing was unexplored until now.

Alterations in type 2 dopamine receptors across neuropsychiatric conditions: A large-scale PET cohort

PURPOSE

Aberrant dopaminergic function is linked with motor, psychotic, and affective symptoms, but studies have typically compared a single patient group with healthy controls.

METHODS

Here, we investigated the variation in striatal (caudate nucleus, nucleus accumbens, and putamen) and thalamic type 2 dopamine receptor (D2R) availability using [11C]raclopride positron emission tomography (PET) data from a large sample of 437 humans including healthy controls, and subjects with Parkinson's disease (PD), antipsychotic-naïve schizophrenia, severe violent behavior, pathological gambling, depression, and overweight. We analyzed regional group differences in D2R availability. We also analyzed the interregional correlation in D2R availability within each group.

RESULTS

Subjects with PD showed the clearest decline in D2R availability. Overall, the groups showed high interregional correlation in D2R availability, while this pattern was weaker in violent offenders. Subjects with schizophrenia, pathological gambling, depression, or overweight did not show clear changes in either the regional receptor availability or the interregional correlation.

CONCLUSION

We conclude that the dopaminergic changes in neuropsychiatric conditions might not only affect the overall receptor availability but also how coupled regions are across people. The region-specific receptor availability more profoundly links to the motor symptoms, while the between-region coupling might be disrupted in violence.

Surface-Activated Pencil Graphite Electrode for Dopamine Sensor Applications: A Critical Review

Pencil graphite electrode (PGE) is an alternative, commercially available, ready-to-use, screen-printed electrode for a wide range of electroanalytical applications. Due to the complex-matrix composition and unpredictable electro-inactive nature of PGE in its native form, a surface pre-treatment/activation procedure is highly preferred for using it as an electroactive working electrode for electroanalytical applications. In this article, we review various surface pre-treatment and modification procedures adopted in the literature with respect to the sensitive and selective detection of dopamine as a model system. Specific generation of the carbon-oxygen functional group, along with partial surface exfoliation of PGE, has been referred to as a key step for the activation. Based on the Scopus^® index, the literature collection was searched with the keywords "pencil and dopamine". The obtained data were segregated into three main headings as: (i) electrochemically pre-treated PGE; (ii) polymer-modified PGEs; and (iii) metal and metal nanocomposite-modified PGE. This critical review covers various surface activation procedures adopted for the activation for PGE suitable for dopamine electroanalytical application.

Monoamine-oxidase Type B Inhibitors and Cognitive Functions in Parkinson's Disease: Beyond the Primary Mechanism of Action

Symptoms of cognitive impairment are rather common since the early stage of Parkinson's disease (PD); they aggravate with disease progression and may lead to dementia in a significant proportion of cases. Worsening of cognitive symptoms in PD patients depends on the progression of subcortical dopaminergic damage as well as the involvement of other brain neurotransmitter systems in cortical and subcortical regions. Beyond the negative impact on disability and quality of life, the presence and severity of cognitive symptoms may limit adjustments of dopamine replacement therapy along the disease course. This review focuses on the consequences of the administration of monoamine-oxidase type Binhibitors (MAOB-I) on cognition in PD patients. Two drugs (selegiline and rasagiline) are available for the treatment of motor symptoms of PD as monotherapy or in combination with L-DOPA or dopamine agonists in stable and fluctuating patients; a further drug (safinamide) is usable in fluctuating subjects solely. The results of available studies indicate differential effects according to disease stage and drug features. In early, non-fluctuating patients, selegiline and rasagiline ameliorated prefrontal executive functions, similarly to other dopaminergic drugs. Benefit on some executive functions was maintained in more advanced, fluctuating patients, despite the tendency of worsening prefrontal inhibitory control activity. Interestingly, high-dose safinamide improved inhibitory control in fluctuating patients. The benefit of high-dose safinamide on prefrontal inhibitory control mechanisms may stem from its dual mechanism of action, allowing reduction of excessive glutamatergic transmission, in turn secondary to increased cortical dopaminergic input.

Dementia-Associated Compulsive Singing (DACS): Presentation of Unpublished Clinical Cases Miniseries

Dementia-associated compulsive singing (DACS) is a neurotransmettitorial-based behavioral disturbance, characterized by an unabating melodic expression, occurring in patients that suffer from evolved dementia. Previously described only as a "punding" aspect of the dopamine dysregulation syndrome (DDS) in the Parkinson's disease (PD), compulsive singing has now been described, for the first time, in four non-PD patients effectively treated with Haloperidol or Quetiapine. Unlike the DDS-associated conditions, in our cases DACS is not pharmacologically induced, being that all patients were L-dopa-free. We detected a diffuse hyperintensity of the white matter and brain atrophy, with insular shrinkage as well as ventricular system and/or sub-arachnoid space enlargement in our DACS patients. Furthermore, similarly to the other behavioral symptoms of dementia, DACS also seems to be correlated to the degree of cognitive and functional impairment, rather than its subtype. In conclusion, DACS is a non-cognitive, unpublished clinical aspect of evolved dementia, which is interesting due to the involvement of the extra-nigral dopaminergic system, resulting in an unabating altered behavior, but also to the enrichment of our knowledge in the involutional diseases of the central nervous system and their physiopathological manifestations.

Sexual dysfunction with major depressive disorder and antidepressant treatments: impact, assessment, and management

INTRODUCTION

Sexual dysfunction (SD) is a symptom of depression in ≈70% of patients presenting with major depressive disorder (MDD). Antidepressant medications (AD) and adjunctive treatments may further contribute to SD and complicate evaluation and management.

AREAS COVERED

A systematic literature search of PubMed, Ovid MEDLINE and Cochrane databases for MDD, SD, classes of antidepressants, etc. was performed with a focus on 2014 to June 2021. SSRIs are associated with 70% treatment-emergent sexual dysfunction (TESD), SNRIs and tricyclics have rates of TESD of 40 - 45%, and antidepressant medications without SRI effects or with additional unique mechanisms of action have rates similar to placebo (<10%). Appropriate assessment at baseline and throughout treatment, consideration of patient preferences in prescribing, addressing modifiable factors (comorbid medical/psychiatric conditions, substances, relationship difficulties), and utilizing management strategies of switching to an AD with less SD, adding an antidote/adjunctive therapy or lowering the dose are discussed.

EXPERT OPINION

MDD and antidepressant treatment contribute to SD in a high percentage of patients. Treating to remission reduces SD as a symptom of depression. Frequent assessment and targeted management strategies may be effective in preventing or addressing SD. Secondary outcomes like impact on adherence, relationships and self-image should also be considered.

Deficiency in RCAT-1 Function Causes Dopamine Metabolism Related Behavioral Disorders in Caenorhabditis elegans

When animals are faced with food depletion, food search-associated locomotion is crucial for their survival. Although food search-associated locomotion is known to be regulated by dopamine, it has yet to investigate the potential molecular mechanisms governing the regulation of genes involved in dopamine metabolism (e.g., cat-1, cat-2) and related behavioral disorders. During the studies of the pheromone ascaroside, a signal of starvation stress in C. elegans, we identified R02D3.7, renamed rcat-1 (regulator of cat genes-1), which had previously been shown to bind to regulatory sequences of both cat-1 and cat-2 genes. It was found that RCAT-1 (R02D3.7) is expressed in dopaminergic neurons and functions as a novel negative transcriptional regulator for cat-1 and cat-2 genes. When a food source becomes depleted, the null mutant, rcat-1(ok1745), exhibited an increased frequency of high-angled turns and intensified area restricted search behavior compared to the wild-type animals. Moreover, rcat-1(ok1745) also showed defects in state-dependent olfactory adaptation and basal slowing response, suggesting that the mutants are deficient in either sensing food or locomotion toward food. However, rcat-1(ok1745) has normal cuticular structures and locomotion genes. The discovery of rcat-1 not only identifies a new subtype of dopamine-related behaviors but also provides a potential therapeutic target in Parkinson’s disease.

Management strategies of sexual dysfunctions in Parkinson's disease

Sexual dysfunctions (SD) are frequent and highly disabling nonmotor manifestations of Parkinson's disease (PD) but are also potentially treatable. Neurologists should actively discuss, recognize and treat sexual health issues as an integral part of the management of the disease. In this chapter, we provide recommendations for managing and treating both primary and secondary SD in PD. Many sexual problems can be, at least partially, improved by adjusting the treatment of motor, nonmotor symptoms and comorbidities. Although some treatments of primary SD are evidence-based, many therapeutic options have not been yet systematically studied in patients with PD. The development of new treatments and repurposing of existing remedies in patients with PD remain an unmet need.

Predicting Parkinson's disease using gradient boosting decision tree models with electroencephalography signals

INTRODUCTION

Parkinson's disease (PD) is a neurodegenerative disorder with only symptomatic treatments currently available. Although correct, early diagnoses of PD are important, the existing diagnostic method based on pathologic examinations only has an accuracy of approximately 80.6%. Although electroencephalography (EEG)-based assistive technology has been introduced, it has been difficult to implement in practice due to the high computational complexity and low accuracy of the analysis methods. This study proposed a fast, accurate PD prediction method using the Hjorth parameter and the gradient boosting decision tree (GBDT) algorithm.

METHOD

We used an open EEG dataset with 41 PD patients and 41 healthy controls (HCs); EEG signals were recorded from participants at the University of New Mexico (PD: 27 vs. HC: 27) and University of Iowa (PD: 14 vs. HC: 14). We explored the analytic time segment and frequency range in which the Hjorth parameter best represents the EEG characteristics of PD patients.

RESULTS

Our best model (CatBoost-based) distinguished PD patients from controls with an accuracy of 89.3%, an area under the receiver operating characteristics curve (AUC) of 0.912, an F-score of 0.903, and an odds ratio of 115.5. These results showed that our models outperformed those of all other previous works and were even superior to previously known pathologic examination-based diagnoses with long-term follow-up (accuracy = 83.9%).

CONCLUSION

The proposed methods are expected to be utilized as an effective method for improving the diagnosis of PD.

Current Therapies in Clinical Trials of Parkinson's Disease: A 2021 Update

Parkinson's disease (PD) is a progressive neurodegenerative disorder that currently has no cure, but treatments are available to improve PD symptoms and maintain quality of life. In 2020, about 10 million people worldwide were living with PD. In 1970, the United States Food and Drug Administration approved the drug levodopa as a dopamine replacement to manage PD motor symptoms; levodopa-carbidopa combination became commercialized in 1975. After over 50 years of use, levodopa is still the gold standard for PD treatment. Unfortunately, levodopa therapy-induced dyskinesia and OFF symptoms remain unresolved. Therefore, we urgently need to analyze each current clinical trial's status and therapeutic strategy to discover new therapeutic approaches for PD treatment. We surveyed 293 registered clinical trials on ClinicalTrials.gov from 2008 to 16 June 2021. After excluded levodopa/carbidopa derivative add-on therapies, we identified 47 trials as PD treatment drugs or therapies. Among them, 19 trials are in phase I (41%), 25 trials are in phase II (53%), and 3 trials are in phase III (6%). The three phase-III trials use embryonic dopamine cell implant, 5-HT_1A receptor agonist (sarizotan), and adenosine A_2A receptor antagonist (caffeine). The therapeutic strategy of each trial shows 29, 5, 1, 5, 5, and 2 trials use small molecules, monoclonal antibodies, plasma therapy, cell therapy, gene therapy, and herbal extract, respectively. Additionally, we discuss the most potent drug or therapy among these trials. By systematically updating the current trial status and analyzing the therapeutic strategies, we hope this review can provide new ideas and insights for PD therapy development.

Copper oxide integrated perylene diimide self-assembled graphitic pencil for robust non-enzymatic dopamine detection

Exploring a robust, extremely sensitive, cost-effective and reliable assay platform for the precise analysis of dopamine (DA) has become a big challenge predominantly at the clinical level. To participate in this quest, herein, we fabricated a perylene diimide (PDI) self-assembled graphitic surface of the graphitic pencil electrode (GPE) anchored copper oxide (CuO). The self-assembled N-rich PDI led to the fast movement of ions by decreasing the bandgap and improved the electron transport kinetics with more exposed catalytic active sites, thus resulting in the robust electrochemical sensing of DA. The designed sensor exhibited good sensitivity (4 μM-1 cm-2), high structural stability, repeatability and excellent reproducibility with an RSD value of 2.9%. Moreover, the developed system showed a wide linear range (5 μM to 500 μM) and reliable selectivity even in the presence of co-existing interferants, such as ascorbic acid and uric acid. The fabricated nanohybrid was eventually employed to analyze DA in spiked physiological fluids and provided satisfactory recoveries. The designed PDI-CuO based interface also showed a very low detection limit of 6 nM (S/N = 3), consequently confirming its suitability for clinical and biological applications.

Factors Associated with Medication Beliefs in Patients with Parkinson's Disease: A Cross-Sectional Study

OBJECTIVE

Medication beliefs are a significant determinant of medication adherence in chronic illness. This study aimed to identify demographic, clinical, and medication-related factors associated with medication beliefs in patients with Parkinson's disease (PD).

METHODS

We used a descriptive cross-sectional design with a convenience sample of 173 PD patients who had been taking antiparkinson drugs for more than one year.

RESULTS

The subjects who believed PD medication was more necessary had more severe illness, younger age of onset, longer illness duration, and longer duration of levodopa therapy. They had higher levels of non-motor symptoms and depression, number of medication uses, number of drugs, and levodopa equivalent dose, and they reported fluctuation of motor symptoms and dyskinesia. The subjects who used catechol-O-methyltransferase (COMT) inhibitors, dopamine agonists, amantadine, and monoamine oxidase-B (MAO-B) inhibitors had significantly higher necessity scores than those who did not use them. The subjects who had higher concerns about PD medications had higher levels of non-motor symptoms and depression. The subjects using amantadine and anticholinergics had significantly higher concern scores than those who did not use them. Positive necessity-concerns differentials were associated with severe illness, the presence of motor fluctuation and dyskinesia, and the use of COMT inhibitors. Based on stepwise multiple regression, the most significant factors influencing necessity beliefs were severe illness, followed by depression and motor fluctuation.

CONCLUSION

Severe illness, higher levels of depression, and motor fluctuation are independent factors influencing patients' beliefs regarding medication necessity. Therefore, these characteristics should be considered in medication belief assessment and interventions for PD patients.

Advanced Therapies for the Management of Dopamine Dysregulation Syndrome in Parkinson's Disease

Background

Dopamine Dysregulation Syndrome (DDS) is an adverse non-motor complication of dopamine replacement therapy in Parkinson's disease. The current literature on this syndrome is limited, and it remains underdiagnosed and challenging to manage.

Objective

To assess the role of advanced therapies in the management of DDS.

Methods

We performed a retrospective chart review and identified patients who fit the inclusion criteria for DDS. They were classified according to risk factors that have been identified in the literature, motor and complication scores, intervention (medical or surgical) and outcome. Multivariate analyses were performed to analyze these characteristics.

Results

Twenty-seven patients were identified (23 males, mean age of onset: 49 ± 8.8 years). Average levodopa equivalent daily dose was 1916.7 ± 804 mg and a history of impulse control disorders, psychiatric illness, and substance abuse was present in 89%, 70% and 3.7% of the patients, respectively. Overall 81.5% of patients had symptom resolution at follow up, on average 4.8 ± 3.5 years after management, with medication only (7/9), levodopa-carbidopa intestinal gel (1/3), deep brain stimulation of subthalamic nucleus (10/13), or globus pallidus pars interna (2/2). Reduction of medications occurred with deep brain stimulation of subthalamic nucleus (P = 0.01) but was associated with a relapse in two patients.

Conclusion

Although the small sample size of some subgroups limits our ability to draw meaningful conclusions, our results did not suggest superiority of a single treatment option. Advanced therapies including deep brain stimulation can be considered in patients with DDS refractory to conservative measures, but outcome is variable and relapse is possible.

Evaluation of the cellular protection by novel spiropyrazole compounds in dopaminergic cell death

The loss of neurons is strongly correlated with aging and aging-associated disorders. In this study, cell viability assays and mitochondrial function were performed to evaluate the effect of new spiro-pyrazole derivatives, prepared from aldehydes and 3-amino-1-phenyl-2-pyrazolin-5-one, on neuroprotection in an in vitro model of dopaminergic cell death induced by 1-methyl-4-phenylpyridinium (MPP⁺). The percentages of neuroprotection by derivatives were found between 21.26% and 52.67% at selected concentrations (10-50 μM) with compound 4d exerting the best neuroprotective effect. The results show that the studied spiropyrazolones perform important roles in dopaminergic neuroprotection and can be used for potential new therapies in the treatment of neurodegenerative disorders including Parkinson's disease.

Accelerated habitual learning resulting from L-dopa exposure in rats is prevented by N-acetylcysteine

Instrumental actions are initially goal-directed and driven by their associated outcome. However, with repeated experience habitual actions develop which are automated and efficient, as they are instead driven by antecedent stimuli. Dopamine is thought to facilitate the transition from goal-directed to habitual actions. This idea has been largely derived from evidence that psychostimulants accelerate the development of habitual actions. In the current study, we examined the impact of L-dopa (levodopa or L-dihydroxyphenylalanine), which also potentiates dopamine activity, on habitual learning. L-dopa was systemically administered prior to training rats to press a lever for a food outcome. When tested, L-dopa exposed animals were insensitive to changes in the value of the food outcome, and hence demonstrated accelerated habitual behavioral control compared to control animals that remained goal directed. We also showed that when N-acetylcysteine (NAC), an antioxidant and regulator of glutamate activity, was co-administered with L-dopa, it prevented the transition to habitual behavior; an effect demonstrated previously for cocaine. Therefore, this study establishes similarities between L-dopa and psychostimulants in both the development and prevention of habitual actions, and supports the notion that excess dopamine potentiates habitual learning. This finding extends the limited existing knowledge of the impact of L-dopa on learning and behavior, and has implications for neurological disorders where L-dopa is the primary treatment.

[The role of inhibitors of COMT and MAO-B in the therapy of Parkinson's disease]

Inhibitors of COMT and MAO-B are well established in the pharmacotherapy of Parkinson's disease (PD). MAO-B inhibitors are used as monotherapy as well as in combination with levodopa, whereas COMT inhibitors exert their effects only in conjungtion with levodopa. Both classes of compounds prolong the response duration of levodopa and optimise its clinical benefit. As a result, the ON-times are prolonged significantly. In the past, MAO-B inhibitors were also adminstered for neuroprotection; however, despite convincing scientific reasoning in support of neuroprotective effects, these could not be substantiated in clinical studies performed so far.

Gold nanoparticle-based detection of dopamine based on fluorescence resonance energy transfer between a 4-(4-dialkylaminostyryl)pyridinium derived fluorophore and citrate-capped gold nanoparticles

A colorimetric/fluorometric dual-signal assay is described for the determination of dopamine (DA). A nanoprobe was obtained by linking a 4-(4-dialkylaminostyryl)pyridinium derived fluorophore to citrate-capped gold nanoparticles (AuNPs). The fluorescence of the fluorophore is quenched by the AuNPs via fluorescence resonance energy transfe. In the presence of DA, the catechol group of DA can absorb on the surface of AuNPs to induce aggregation, which is accompanied by a color change from red to blue. The yellow fluorescence of the fluorophore with excitation/emission maximum at 365/570 nm is recovered. The dual-signal detection allows the quantitative analysis of DA within 300 μM by the colorimetric method and 80 μM by the fluorometric method. The detection limits for the colorimetric/fluorometric methods are 1.85 μM and 0.29 μM, respectively. Quantitative determination of DA in spiked urine samples was successfully demonstrated, with recoveries ranging from 98.2 to 106.0%. Graphical abstract A colorimetric/fluorometric dual-signal assay is described for the determination of dopamine by linking a fluorophore to gold nanoparticles. The dopamine causes aggregation of the nanoparticles to induce color change, which is followed by the recovery of the fluorescence.

Impulse control disorders in Parkinson's disease: A systematic review on the psychometric properties of the existing measures

Background

A significant percentage of patients suffering from Parkinson’s Disease (PD) experience Impulse Control Disorders (ICDs), contributing to reduced quality of life. As they can be managed by reducing the dopamine dosage, the detection of their presence is crucial for PD treatment plan. Nevertheless, they tend to be under-recognized in clinical practice, since routine screening is not common–despite existing instruments that may support clinicians. This work presents a systematic review on the psychometric properties of instruments measuring ICDs in PD, to test whether clinicians dispose of valid tools that may help them in clinical assessment.

Method

A systematic literature search in three databases (EMBASE, MEDLINE, and PsycINFO) was conducted. Quality of the instruments’ psychometric properties was evaluated with Terwee et al.’s criteria, and methodological quality of the studies was evaluated with the COSMIN Checklist.

Results

Ten studies examining seven instruments were selected. The Questionnaire for Impulsive-Compulsive Disorders in Parkinson’s Disease (QUIP) and the Ardouin Scale of Behavior in Parkinson’s Disease (ASBPD) resulted to be the best from a psychometric point of view.

Conclusions

Though the gold standard for diagnosis remains a detailed diagnostic interview, this review will encourage clinicians to use validated tools to accurately assess ICDs.

Bionanotube/Poly(3,4-ethylenedioxythiophene) Nanohybrid as an Electrode for the Neural Interface and Dopamine Sensor

Poly(3,4-ethylene dioxythiophene) (PEDOT) is a promising conductive material widely used for interfacing with tissues in biomedical fields because of its unique properties. However, obtaining high charge injection capability and high stability remains challenging. In this study, pristine carbon nanotubes (CNTs) modified by dopamine (DA) self-polymerization on the surface polydopamine (PDA@CNTs) were utilized as dopants of PEDOT to prepare hybrid films through electrochemical deposition on the indium tin oxide (ITO) electrode. The PDA@CNTs-PEDOT film of the nanotube network topography exhibited excellent stability and strong adhesion to the ITO substrate compared with PEDOT and PEDOT/ p-toulene sulfonate. The PDA@CNTs-PEDOT-coated ITO electrodes demonstrated lower impedance and enhanced charge storage capacity than the bare ITO. When applying exogenous electrical stimulation (ES), robust long neurites sprouted from the dorsal root ganglion (DRG) neurons cultured on the PDA@CNTs-PEDOT film. Moreover, ES promoted Schwann cell migration out from the DRG spheres and enhanced myelination. The PDA@CNTs-PEDOT film served as an excellent electrochemical sensor for the detection of DA in the presence of biomolecule interferences. Results would shed light into the advancement of conducting nanohybrids for applications in the multifunctional bioelectrode in neuroscience.

EEG coherence as a diagnostic tool to measure the initial stages of Parkinson Disease

Although Parkinson Disease was described a long time ago by James Parkinson and several biomarkers were used to predict the symptoms of PD, there is no accepted tool to distinguish the initial stages of this pathology. The present hypothesis discusses the Coherence Function, an Electroencephalography measure which could be used as a simple, and low-cost tool to describe the onset of cardinal signals of PD. Our hypothesis is based on three factors: beta frequency related to movement, motor action over particular cortical regions, and cortical coupling between cortical areas involved in the execution of voluntary movement. We believe that these factors support our hypothesis pointing out coherence function as an interesting measure to detect initial stages of PD.

Biosynthesis of Copper Oxide (CuO) Nanowires and Their Use for the Electrochemical Sensing of Dopamine

A facile one-step, eco-friendly, and cost-effective approach for the formation of copper oxide (CuO) nanowires by a green method using saponin-rich Sapindus mukorossi fruit extract (SMFE). The physio-chemical characteristics of the synthesized CuO nanowires have been characterized by X-ray Diffractometry (XRD), X-ray Photoelectron Spectroscopy (XPS), FT-IR (Fourier Transform Infrared Spectroscopy, FE-SEM (Scanning Electron Microscopy), and High-Resolution Transmission Electron Microscopy (HR-TEM). Further, the electrocatalytic activity of the CuO nanowires synthesized with SMFE has been investigated, and they have been used as dopamine (DA) sensors. Because of their unique properties, the CuO nanowires/GCE exhibited remarkable electrochemical response for the detection of DA with enhanced current response. The anodic current demonstrated that the CuO nanowires/GCE linearly detects the concentration of DA over the range of 0.1 µM to 0.105 mM of DA with a regression co-efficient of 0.9960. The obtained results illustrated that the synthesized CuO nanowires can easily stimulate the electron transfer reaction between DA and the nanowires modified electrode with the improvement of the conductivity and stability of the electrode. This remarkable electrocatalytic property of CuO nanowires makes it a unique electrochemical sensor for the detection of DA. Furthermore, the sensor is free from the interference of ascorbic acid, uric acid, and other interfering species. Moreover, the anti-interference performance also showed that the CuO nanowires/GCE could be employed for the determination of DA in real samples with good selectivity and sensitivity.

A Fluorescent Biosensors for Detection Vital Body Fluids' Agents

The clinical applications of sensing tools (i.e., biosensors) for the monitoring of physiologically important analytes are very common. Nowadays, the biosensors are being increasingly used to detect physiologically important analytes in real biological samples (i.e., blood, plasma, urine, and saliva). This review focuses on biosensors that can be applied to continuous, time-resolved measurements with fluorescence. The material presents the fluorescent biosensors for the detection of neurotransmitters, hormones, and other human metabolites as glucose, lactate or uric acid. The construction of microfluidic devices based on fluorescence uses a variety of materials, fluorescent dyes, types of detectors, excitation sources, optical filters, and geometrical systems. Due to their small size, these devices can perform a full analysis. Microfluidics-based technologies have shown promising applications in several of the main laboratory techniques, including blood chemistries, immunoassays, nucleic-acid amplification tests. Of the all technologies that are used to manufacture microfluidic systems, the LTCC technique seems to be an interesting alternative. It allows easy integration of electronic and microfluidic components on a single ceramic substrate. Moreover, the LTCC material is biologically and chemically inert, and is resistant to high temperature and pressure. The combination of all these features makes the LTCC technology particularly useful for implementation of fluorescence-based detection in the ceramic microfluidic systems.

A MOF-based carrier for in situ dopamine delivery

MIL-88A (Fe) MOF crystals were nucleated and grown around a polymer core containing superparamagnetic nanoparticles to assemble a new class of biocompatible particles for magnetophoretic drug delivery of dopamine. The carrier enabled efficient targeted release, dopamine protection from oxidative damage, long-term delivery and improved drug delivery cost-efficiency. After loading, dopamine was stable within the carrier and did not undergo oxidation. Drug release monitoring via spectrofluorimetry revealed a shorter burst effect and higher release efficiency than silica based carriers. The in vitro cytotoxicity at different MOF concentrations and sizes was assessed using PC12 cells as the neuronal cell model. The drug was directly uptaken into the PC12 cells avoiding possible side effects due to oxidation occurring in the extracellular environment.

Silver nanoparticles decorated eggshell membrane as an effective platform for interference free sensing of dopamine

In this paper a simple electrochemical sensing of dopamine by a new effective immobilization of tyrosinase (Tyr) enzyme on eggshell membrane (ESM) along with silver nanoparticles (AgNPs) is reported. The modified membrane was characterized by scanning electron microscope (SEM), energy dispersive spectroscopy (EDAX), X-Ray diffraction (XRD). A simple solution based approach was used to prepare AgNPs on biomembrane followed by glutaraldehyde activation to immobilize Tyr on the nanoparticles decorated ESM. The direct electrochemistry of DA oxidation was performed through cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Characterization of membrane was accomplished by electrochemical impedance spectroscopy (EIS). Prepared electrode showed very good stability, reproducibility, high selectivity, easy preparation and regeneration of electrode. The proposed sensor exhibited low detection limits 1.7ngL^-1 with wide linear range 10-1000 ngL^-1, excellent sensitivity (14.28µA µgL^-1cm^-2) with good storage and operational stabilities. The accurate measurement of dopamine in blood serum and good recoveries in spiked serum samples ensured great potential for medical diagnostics.

Markers of impaired motor and cognitive volition in Parkinson's disease: Correlates of dopamine dysregulation syndrome, impulse control disorder, and dyskinesias

INTRODUCTION

Dopaminergic therapy in Parkinson's disease (PD) can be associated with both motoric (e.g., dyskinesias) and neuropsychiatric adverse effects. Examples of the latter include Dopamine Dysregulation Syndrome (DDS) and impulse control disorder (ICD), which are separate but related behavioral/psychiatric complications of treatment in PD. Dysregulation of volition characterizes both dyskinesias and DDS/ICD; thus, we analyzed potential disease-related correlates in a large PD cohort.

METHODS

We analyzed cross-sectional data from 654 participants collected through the NINDS Parkinson's Disease Biomarkers Program. DDS/ICD symptoms and dyskinesias were assessed using the Movement Disorders Society (revised) Unified Parkinson's Disease Rating Scale. Potential associated variables were selected from PD-validated or PD-specific scales of neuropsychiatric or motoric status. Multivariable models with DDS/ICD or dyskinesia presence outcomes were produced with backward stepwise regression to identify factors independently associated with DDS/ICD and/or dyskinesias.

RESULTS

Fifty-three (8.1%) participants endorsed DDS and/or ICD symptoms and 150 (22.9%) were dyskinetic. In multivariable analysis, psychosis was independently associated with both dyskinesias (p = 0.006) and DDS/ICD (p < 0.001). Unpredictable motor fluctuations (p = 0.026) and depression (p = 0.023) were also associated with DDS/ICD; female sex (p = 0.025), low tremor score (p = 0.001) and high akinesia-rigidity score (p < 0.001) were associated with dyskinesias.

CONCLUSIONS

Our findings suggest that psychosis may be an important marker of impaired volition across motor and cognitive domains. Unpredictable motor fluctuations, psychosis, and depression may together comprise a phenotypic profile of patients at increased risk for DDS/ICD. Similarly, dyskinetic PD patients should be closely monitored for psychotic symptoms and treated appropriately.

Multidisciplinary Perspectives for Alzheimer's and Parkinson's Diseases: Hydrogels for Protein Delivery and Cell-Based Drug Delivery as Therapeutic Strategies

This review presents two intriguing multidisciplinary strategies that might make the difference in the treatment of neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. The first proposed strategy is based on the controlled delivery of recombinant proteins known to play a key role in these neurodegenerative disorders that are released in situ by optimized polymer-based systems. The second strategy is the use of engineered cells, encapsulated and delivered in situ by suitable polymer-based systems, that act as drug reservoirs and allow the delivery of selected molecules to be used in the treatment of Alzheimer's and Parkinson's diseases. In both these scenarios, the design and development of optimized polymer-based drug delivery and cell housing systems for central nervous system applications represent a key requirement. Materials science provides suitable hydrogel-based tools to be optimized together with suitably designed recombinant proteins or drug delivering-cells that, once in situ, can provide an effective treatment for these neurodegenerative disorders. In this scenario, only interdisciplinary research that fully integrates biology, biochemistry, medicine and materials science can provide a springboard for the development of suitable therapeutic tools, not only for the treatment of Alzheimer's and Parkinson's diseases but also, prospectively, for a wide range of severe neurodegenerative disorders.

Finely Composition-Tunable Synthesis of Ultrafine Wavy PtRu Nanowires as Effective Electrochemical Sensors for Dopamine Detection

Preparing Pt-based one-dimensional (1D) ultrafine nanowires with abundant structural defects/grain boundaries and exploring their novel applications have attracted great interest in real-world applications. Here we introduce an environmentally friendly, facile aqueous solution approach to directly prepare a series of sub-3.0 nm PtRu ultrafine wavy nanowires. Characterizations show that the PtRu nanowires are alloy polycrystalline structures with abundant structural defects/grain boundaries. We first introduce the as-synthesized PtRu nanowires into electrochemical biosensors for the detection of DA and find that the Pt₇Ru₃ nanowires exhibit excellent electrocatalytic activity to DA with fast response, ultralow limit of detection, and excellent selectivity at a potential of 0.3 V in 0.1 M phosphate buffered solution (pH 7.2). This study shows an effective approach to the development of ultrafine PtRu nanowires as electrocatalysts for electrochemical nonenzymatic dopamine biosensors.

One-pot synthesis of dendritic Pt3Ni nanoalloys as nonenzymatic electrochemical biosensors with high sensitivity and selectivity for dopamine detection

Preparation of Pt-based nanocatalysts with high catalytic activity and exploration of their novel applications have attracted significant interest in the nanoscale field. Herein, we report a facile synthesis of dendritic Pt₃Ni nanoalloys and their applications for electrochemical nonenzymatic dopamine biosensors. As a result of their unique structure, the dendritic Pt₃Ni nanoalloys show high electrocatalytic activity towards dopamine oxidation. Amperometric dopamine biosensors based on dendritic Pt₃Ni nanoalloy microelectrode exhibit a wide linear detection ranges from 0.5 μM to 250 μM with ultrahigh sensitivity, fast response, and excellent selectivity at a potential of 0.3 V in a 0.1 M phosphate buffered solution (pH = 7.2). The limit of detection on dendritic Pt₃Ni nanoalloy microelectrodes can decrease down to 10 nM, which is the least concentration of dopamine in serum samples with a value of sensitivity up to 4.6 μA mg^-1_Pt cm^-2. This study shows an effective approach for the development of dendritic Pt₃Ni nanoalloys as electrocatalysts for electrochemical nonenzymatic dopamine biosensors.

Psychiatric and Cognitive Effects of Deep Brain Stimulation for Parkinson's Disease

Deep brain stimulation (DBS) is effective for Parkinson's disease (PD), dystonia, and essential tremor (ET). While motor benefits are well documented, cognitive and psychiatric side effects from the subthalamic nucleus (STN) and globus pallidus interna (GPi) DBS for PD are increasingly recognized. Underlying disease, medications, microlesions, and post-surgical stimulation likely all contribute to non-motor symptoms (NMS).

Chronic pramipexole treatment induces compulsive behavior in rats with 6-OHDA lesions of the substantia nigra and ventral tegmental area

Dopamine replacement therapy (DRT) reduces motor symptoms in Parkinson's disease (PD), but also induces impulsive-compulsive behavior (ICB) in up to 25% of PD patients. These non-motor side effects of DRT generally follow a gradual transition from impulsive to compulsive-like-i.e. repetitive, compelled, and non-pleasurable-behavior. Here, we investigated the effect of chronic pramipexole (PPX) treatment on the onset of compulsive-like behavior, measured via the post-training signal attenuation (PTSA) procedure, in rats with dopaminergic lesions. Accordingly, we aimed to mimic chronic DRT in a PD context, and obtain data on the brain regions that potentially sustain this type of compulsive behavior pattern in rats. We observed that the lesion or treatment alone did not induce compulsive lever pressing in rats. However, rats with lesions of the substantia nigra and ventral tegmental area as well as with chronic PPX treatment developed strong compulsive lever-pressing behavior, as measured via PTSA. Furthermore, when chronic PPX treatment was discontinued before the PTSA test, the lesioned rats showed the same level of compulsive behavior as sham-operated rats. In fact, lesioned, treated, and compulsive-like rats showed significantly higher Fos expression in the orbitofrontal cortex and dorsal striatum. Thus, chronic PPX treatment in PD rats induced a strong compulsive-like behavior. Furthermore, Fos expression mapping suggests that the behavior was sustained via the activation of the orbitofrontal cortex and dorsal striatum.

Region Specific Effects of Aging and the Nurr1-Null Heterozygous Genotype on Dopamine Neurotransmission

The transcription factor Nurr1 is essential for dopamine neuron differentiation and is important in maintaining dopamine synthesis and neurotransmission in the adult. Reduced Nurr1 function, due to the Nurr1-null heterozygous genotype (+/-), impacts dopamine neuron function in a region specific manner resulting in a decrease in dopamine synthesis in the dorsal and ventral striatum and a decrease in tissue dopamine levels in the ventral striatum. Additionally, maintenance of tissue dopamine levels in the dorsal striatum and survival of nigrostriatal dopamine neurons with aging (>15 months) or after various toxicant treatments are impaired. To further investigate the effects of aging and the Nurr1-null heterozygous genotype, we measured regional tissue dopamine levels, dopamine neuron numbers, body weight, open field activity and rota-rod performance in young (3-5 months) and aged (15-17 months) wild-type +/+ and +/- mice. Behavioral tests revealed no significant differences in rota-rod performance or basal open field activity as a result of aging or genotype. The +/- mice did show a significant increase in open field activity after 3 min of restraint stress. No differences in tissue dopamine levels were found in the dorsal striatum. However, there were significant reductions in tissue dopamine levels in the ventral striatum, which was separated into the nucleus accumbens core and shell, in the aged +/- mice. These data indicate that the mesoaccumbens system is more susceptible to the combination of aging and the +/- genotype than the nigrostriatal system. Additionally, the effects of aging and the +/- genotype may be dependent on genetic background or housing conditions. As Nurr1 mutations have been implicated in a number of diseases associated with dopamine neurotransmission, further data is needed to understand why and how Nurr1 can have differential functions across different dopamine neuron populations in aging.

Gold nanocages decorated biocompatible amine functionalized graphene as an efficient dopamine sensor platform

Nanocomposite of gold nanocages and chemically modified graphene oxide (GNCs/CMG) was synthesized in N,N-dimethylformamide (DMF) for sensitive detection of dopamine (DA). DA is widely spread in central nervous system which can regulates essential body functions like movement and emotional behaviour. In this regard sensitive and fast detection of DA level in human body is still challenging considering its interference with other biomolecules in biological samples. CMG was synthesized through amine modification of graphene oxide (GO) with DMF at relatively high temperature followed by attachment of GNCs, fabricated using a galvanic replacement between silver nanocubes and HAuCl₄ solution in the DMF. X-ray diffraction (XRD) pattern of GNCs/CMG nanocomposite revealed high crystallization of GNCs attached to the graphene nanosheets and microscopic images revealed relatively uniform decoration of GNCs on the surface of CMG. Nanocomposite modified glassy carbon electrode (GNCs/CMG/GCE) was used to investigate the electrochemical behaviour of DA with cyclic voltammetry and amperometry techniques. The linear range for dopamine was between 0.1 and 80μM with a low detection limit of 0.02μM. Furthermore, GNCs/CMG/GCE exhibited satisfying reproducibility, long-term stability and high selectivity for DA detection in large amount of ascorbic acid with good results for determination in human serum samples.

Development of a disposable and low-cost electrochemical sensor for dopamine detection based on poly(pyrrole-3-carboxylic acid)-modified electrochemically over-oxidized pencil graphite electrode

In this study, preparation of a single-use electrochemical sensor for the selective and sensitive determination of dopamine (DOP) was investigated by electrochemical polymerization of pyrrole-3-carboxylic acid on electrochemically over-oxidized pencil graphite electrode (p(P3CA)/EOPGE). Cyclic voltammetry measurements of Fe(CN)₆^4-/3- indicated that the electrochemically over-oxidized PGE (EOPGE) showed superior electron transfer characteristics according to bare PGE. The ionized carboxyl groups found in the structure of poly(pyrrole-3-carboxylic acid) (p(P3CA)) showed high affinity towards positively charged DOP. The combination of the advantages of EOPGE and p(P3CA) in p(P3CA)/EOPGE led to a synergistic effect on the electrochemical oxidation of DOP. The effects of experimental variables on the voltammetric performance of the p(P3CA)/EOPGE were examined by preparing the electrodes at different conditions. The p(P3CA)/EOPGE showed high selectivity towards DOP by discriminating its oxidation potential from the common interfering substances such as ascorbic and uric acids. The p(P3CA)/EOPGE showed linear responses in the electrochemical oxidation of DOP between the concentration values of 0.025µM and 7.5µM. Detection limit was determined as 0.0025µM according to signal to noise ratio (S/N: 3). Analytical application of p(P3CA)/EOPGE was successfully tested in the determination of DOP in blood serum and pharmaceutical samples.

A new approach for turn-on fluorescence sensing of l-DOPA

Resa-Sulf, designed based on a redox reaction, was applied for turn-on fluorescence sensing and quantitative detection ofl-DOPA.

Dopamine Replacement Therapy, Learning and Reward Prediction in Parkinson's Disease: Implications for Rehabilitation

The principal feature of Parkinson’s disease (PD) is the impaired ability to acquire and express habitual-automatic actions due to the loss of dopamine in the dorsolateral striatum, the region of the basal ganglia associated with the control of habitual behavior. Dopamine replacement therapy (DRT) compensates for the lack of dopamine, representing the standard treatment for different motor symptoms of PD (such as rigidity, bradykinesia and resting tremor). On the other hand, rehabilitation treatments, exploiting the use of cognitive strategies, feedbacks and external cues, permit to “learn to bypass” the defective basal ganglia (using the dorsolateral area of the prefrontal cortex) allowing the patients to perform correct movements under executive-volitional control. Therefore, DRT and rehabilitation seem to be two complementary and synergistic approaches. Learning and reward are central in rehabilitation: both of these mechanisms are the basis for the success of any rehabilitative treatment. Anyway, it is known that “learning resources” and reward could be negatively influenced from dopaminergic drugs. Furthermore, DRT causes different well-known complications: among these, dyskinesias, motor fluctuations, and dopamine dysregulation syndrome (DDS) are intimately linked with the alteration in the learning and reward mechanisms and could impact seriously on the rehabilitative outcomes. These considerations highlight the need for careful titration of DRT to produce the desired improvement in motor symptoms while minimizing the associated detrimental effects. This is important in order to maximize the motor re-learning based on repetition, reward and practice during rehabilitation. In this scenario, we review the knowledge concerning the interactions between DRT, learning and reward, examine the most impactful DRT side effects and provide suggestions for optimizing rehabilitation in PD.

Design and characterization of electrochemical dopamine-aptamer as convenient and integrated sensing platform

Here, an ultrasensitive label-free electrochemical aptasensor was developed for dopamine (DA) detection. Construction of the aptasensor was carried out by electrodeposition of gold-platinum nanoparticles (Au-PtNPs) on glassy carbon (GC) electrode modified with acid-oxidized carbon nanotubes (CNTs-COOH). A designed complementary amine-capped capture probe (ssDNA1) was immobilized at the surface of PtNPs/CNTs-COOH/GC electrode through the covalent amide bonds formed by the carboxyl groups on the nanotubes and the amino groups on the oligonucleotides. DA-specific aptamer was attached onto the electrode surface through hybridization with the ssDNA1. Methylene blue (MB) was used as an electrochemical indicator that was intercalated into the aptamer through the specific interaction with its guanine bases. In the presence of DA, the interaction between aptamer and DA displaced the MB from the electrode surface, rendering a lowered electrochemical signal attributed to a decreased amount of adsorbed MB. This phenomenon can be applied for DA detection. The peak current of probe (MB) linearly decreased over a DA concentration range of 1-30 nM with a detection limit of 0.22 nM.

Dopaminergic modulation of the trade-off between probability and time in economic decision-making

Studies on animals and humans have demonstrated the importance of dopamine in modulating decision-making processes. In this work, we have tested dopaminergic modulation of economic decision-making and its neural correlates by administering either placebo or metoclopramide, a dopamine D2-receptor antagonist, to healthy subjects, during a functional MRI study. The decision-making task combined probability and time delay with a fixed monetary reward. For individual behavioral characterization, we used the Probability Time Trade-off (PTT) economic model, which integrates the traditional trade-offs of reward magnitude-time and reward magnitude-probability into a single measurement, thereby quantifying the subjective value of a delayed and probabilistic outcome. A regression analysis between BOLD signal and the PTT model index permitted to identify the neural substrate encoding the subjective reward-value. Behaviorally, medication reduced the rate of temporal discounting over probability, reflected in medicated subjects being more prone to postpone the reward in order to increase the outcome probability. In addition, medicated subjects showed less activity during the task in the postcentral gyrus as well as frontomedian areas, whereas there were no differences in the ventromedial orbitofrontal cortex (VMOFC) between groups when coding the subjective value. The present study demonstrates by means of behavior and imaging that dopamine modulation alters the probability-time trade-off in human economic decision-making.

Lower limb progressive resistance training improves leg strength but not gait speed or balance in Parkinson's disease: a systematic review and meta-analysis

The use of progressive resistance training (PRT) to improve gait and balance in people with Parkinson’s disease (PD) is an emerging area of interest. However, the main effects of PRT on lower limb functions such as gait, balance, and leg strength in people with PD remain unclear. Therefore, the aim of the meta-analysis is to evaluate the evidence surrounding the use of PRT to improve gait and balance in people with PD. Five electronic databases, from inception to December 2014, were searched to identify the relevant studies. Data extraction was performed by two independent reviewers and methodological quality was assessed using the PEDro scale. Standardized mean differences (SMD) and 95% confidence intervals (CIs) of fixed and random effects models were used to calculate the effect sizes between experimental and control groups and I² statistics were used to determine levels of heterogeneity. In total, seven studies were identified consisting of 172 participants (experimental n = 84; control n = 88). The pooled results showed a moderate but significant effect of PRT on leg strength (SMD 1.42, 95% CI 0.464–2.376); however, no significant effects were observed for gait speed (SMD 0.418, 95% CI −0.219 to 1.055). No significant effects were observed for balance measures included in this review. In conclusion, our results showed no discernable effect of PRT on gait and balance measures, although this is likely due to the lack of studies available. It may be suggested that PRT be performed in conjunction with balance or task-specific functional training to elicit greater lower limb functional benefits in people with PD.

Chronic pramipexole treatment increases tolerance for sucrose in normal and ventral tegmental lesioned rats

The loss of dopamine neurons observed in Parkinson's disease (PD) elicits severe motor control deficits which are reduced by the use of dopamine agonists. However, recent works have indicated that D3-preferential agonists such as pramipexole can induce impulse control disorders (ICDs) such as food craving or compulsive eating. In the present study, we performed an intermittent daily feeding experiment to assess the effect of chronic treatment by pramipexole and VTA bilateral lesion on tolerance for sucrose solution. The impact of such chronic treatment on spontaneous locomotion and spatial memory was also examined. Changes in sucrose tolerance could indicate the potential development of a change in food compulsion or addiction related to the action of pramipexole. Neither the bilateral lesion of the VTA nor chronic treatment with pramipexole altered the spontaneous locomotion or spatial memory in rats. Rats without pramipexole treatment quickly developed a stable intake of sucrose solution in the 12 h access phase. On the contrary, when under daily pramipexole treatment, rats developed a stronger and ongoing escalation of their sucrose solution intakes. In addition, we noted that the change in sucrose consumption was sustained by an increase of the expression of the Dopamine D3 receptor in the core and the shell regions of the nucleus accumbens. The present results may suggest that long-term stimulation of the Dopamine D3 receptor in animals induces a strong increase in sucrose consumption, indicating an effect of this receptor on certain pathological aspects of food eating.

Sexuality in patients with Parkinson's disease, Alzheimer's disease, and other dementias

Sexual dysfunction (SD) is common among patients with Parkinson's disease (PD), Alzheimer's disease (AD), and other dementias. Sexual functioning and well-being of patients with PD and their partners are affected by many factors, including motor disabilities, non-motor symptoms (e.g., autonomic dysfunction, sleep disturbances, mood disorders, cognitive abnormalities, pain, and sensory disorders), medication effects, and relationship issues. The common sexual problems are decreased desire, erectile dysfunction, difficulties in reaching orgasm, and sexual dissatisfaction. Hypersexuality is one of a broad range of impulse control disorders reported in PD, attributed to antiparkinsonian therapy, mainly dopamine agonists. Involvement of a multidisciplinary team may enable a significant management of hypersexuality. Data on SD in demented patients are scarce, mainly reporting reduced frequency of sex and erectile dysfunction. Treatment of SD is advised at an early stage. Behavioral problems, including inappropriate sexual behavior (ISB), are distressing for patients and their caregivers and may reflect the prevailing behavior accompanying dementia (disinhibition or apathy associated with hyposexuality). The neurobiologic basis of ISB is still only vaguely understood but assessment and intervention are recommended as soon as ISB is suspected. Management of ISB in dementia demands a thorough evaluation and understanding of the behavior, and can be treated by non-pharmacologic and pharmacologic interventions.

Preparation of poly(ionic liquids)-functionalized polypyrrole nanotubes and their electrocatalytic application to simultaneously determine dopamine and ascorbic acid

Novel poly(ionic liquids)-functionalized polypyrrole nanotubes presented an excellent performance for simultaneous determination to DA and AA.

Syndrome de dérégulation dopaminergique

La maladie de Parkinson a longtemps été considérée comme un trouble moteur. Dans les années 2000, des séries de cas sont publiées où les patients, traités par agonistes dopaminergiques essentiellement vont présenter une augmentation des conduites tournées vers le plaisir (jeu pathologique, hypersexualité, comportements stéréotypés dits de « punding » et aussi des automédications de dopamine afin de provoquer certains de ces états ou de retrouver un sentiment d’élation pseudomaniaque…). Ces changements comportementaux ont un impact majeur sur le plan psychosocial du patient et de son entourage. La physiopathologie, complexe repose en partie sur la création d’un arc réflexe à la stimulation de dopamine ; le patient sensibilisé au niveau du striatum par la dopamine va présenter une attirance non physiologique à la dopa, compulsive pour limiter les effets de sevrage. Ce « syndrome de dérégulation dopaminergique » parfois nommé « dérégulation homéostatique hédonique dans la maladie de Parkinson », n’est pas rare au sein des patients parkinsoniens, pouvant affecter 5 % de cette population. Il n’existe pas de test paraclinique pour évoquer le diagnostic qui reste donc clinique et repose sur un interrogatoire précis du patient et de son entourage, des critères diagnostiques ayant été proposés en 2005.

Des recommandations sont proposées et comportent un volet préventif (dépistage de sujets à risque) et un volet thérapeutique (stratégies d’optimisation des prescriptions : choix de molécule et des dosages, psychothérapie et gestion des facteurs de risque environnementaux).

Dans cette communication, nous proposons d’aborder les aspects cliniques et les hypothèses physiopathologiques actuelles sur ce trouble, puis dans un deuxième temps, les aspects thérapeutiques validés dans ce trouble.