Motor complications in Parkinson disease: Clinical manifestations and management

Angiotensin-converting enzyme inhibition prevents l-dopa-induced dyskinesia in a 6-ohda-induced mouse model of Parkinson's disease

Parkinson's disease (PD) is characterised by severe movement defects and the degeneration of dopaminergic neurones in the midbrain. The symptoms of PD can be managed with dopamine replacement therapy using L-3, 4-dihydroxyphenylalanine (L-dopa), which is the gold standard therapy for PD. However, long-term treatment with L-dopa can lead to motor complications. The central renin-angiotensin system (RAS) is associated with the development of neurodegenerative diseases in the brain. However, the role of the RAS in dopamine replacement therapy for PD remains unclear. Here, we tested the co-treatment of the angiotensin-converting enzyme inhibitor (ACEI) with L-dopa altered L-dopa-induced dyskinesia (LID) in a 6-hydroxydopamine (6-OHDA)-lesioned mouse model of PD. Perindopril, captopril, and enalapril were used as ACEIs. The co-treatment of ACEI with L-dopa significantly decreased LID development in 6-OHDA-lesioned mice. In addition, the astrocyte and microglial transcripts involving Ccl2, C3, Cd44, and Iigp1 were reduced by co-treatment with ACEI and L-dopa in the 6-OHDA-lesioned striatum. In conclusion, co-treatment with ACEIs and L-dopa, such as perindopril, captopril, and enalapril, may mitigate the severity of L-DOPA-induced dyskinesia in a mouse model of PD.

Real-world Chinese herbal medicine for Parkinson's disease: a hospital-based retrospective analysis of electronic medical records

Background

Parkinson's disease (PD) is a progressive neurodegenerative condition. Chinese medicine therapies have demonstrated effectiveness for PD in controlled settings. However, the utilization of Chinese medicine therapies for PD in real-world clinical practice and the characteristics of patients seeking these therapies have not been thoroughly summarized.

Method

The study retrospectively analyzed initial patient encounters (PEs) with a first-listed diagnosis of PD, based on electronic medical records from Guangdong Provincial Hospital of Chinese Medicine between July 2018 and July 2023.

Results

A total of 3,206 PEs, each corresponding to an individual patient, were eligible for analyses. Approximately 60% of patients made initial visits to the Chinese medicine hospital after receiving a PD diagnosis, around 4.59 years after the onset of motor symptoms. Over 75% of the patients visited the Internal Medicine Outpatient Clinic at their initial visits, while a mere 13.85% visited PD Chronic Care Clinic. Rest tremor (61.98%) and bradykinesia (52.34%) are the most commonly reported motor symptoms, followed by rigidity (40.70%). The most commonly recorded non-motor symptoms included constipation (31.88%) and sleep disturbance (25.27%). Integration of Chinese medicine and conventional medicine therapies was the most common treatment method (39.15%), followed by single use of Chinese herbal medicine (27.14%). The most frequently prescribed herbs for PD included Glycyrrhiza uralensis Fisch. (gan cao), Astragalus mongholicus Bunge (huang qi), Atractylodes macrocephala Koidz. (bai zhu), Angelica sinensis (Oliv.) Diels (dang gui), Rehmannia glutinosa (Gaertn.) DC. (di huang), Paeonia lactiflora Pall. (bai shao), Bupleurum chinense DC. (chai hu), Citrus aurantium L. (zhi qiao/zhi shi/chen pi), Panax ginseng C. A. Mey. (ren shen), and Poria cocos (Schw.) Wolf (fu ling). These herbs contribute to formulation of Bu zhong yi qi tang (BZYQT).

Conclusion

Patients typically initiated Chinese medical care after the establishment of PD diagnosis, ~4.59 years post-onset of motor symptoms. The prevalent utilization of CHM decoctions and patented Chinese herbal medicine products, underscores its potential in addressing both motor and non-motor symptoms. Despite available evidence, rigorous clinical trials are needed to validate and optimize the integration of CHM, particularly BZYQT, into therapeutic strategies for PD.

Mixed-Response State-Space Model for Analyzing Multi-Dimensional Digital Phenotypes

Digital technologies (e.g., mobile phones) can be used to obtain objective, frequent, and real-world digital phenotypes from individuals. However, modeling these data poses substantial challenges since observational data are subject to confounding and various sources of variabilities. For example, signals on patients' underlying health status and treatment effects are mixed with variation due to the living environment and measurement noises. The digital phenotype data thus shows extensive variabilities between- and within-patient as well as across different health domains (e.g., motor, cognitive, and speaking). Motivated by a mobile health study of Parkinson's disease (PD), we develop a mixed-response state-space (MRSS) model to jointly capture multi-dimensional, multi-modal digital phenotypes and their measurement processes by a finite number of latent state time series. These latent states reflect the dynamic health status and personalized time-varying treatment effects and can be used to adjust for informative measurements. For computation, we use the Kalman filter for Gaussian phenotypes and importance sampling with Laplace approximation for non-Gaussian phenotypes. We conduct comprehensive simulation studies and demonstrate the advantage of MRSS in modeling a mobile health study that remotely collects real-time digital phenotypes from PD patients.

Drugs to the Rescue: Comparison of On-Demand Therapies for OFF Symptoms in Parkinson's Disease

Patients with Parkinson's disease often suffer from OFF symptoms disrupting their daily routines and adding to disabilities. Despite polypharmacy and adjustments to medication schedules, they often do not experience consistent relief from their motor symptoms. As the disease progresses, impaired gastric emptying may evolve, making it even more challenging for dopaminergic drugs to provide consistent results. This review focuses on a group of drugs that have the pharmacokinetic advantage of a much earlier onset of action by virtue of their non-oral routes of absorption. We compare the current marketed options: subcutaneous apomorphine, sublingual apomorphine, and inhaled levodopa. Subcutaneous apomorphine is the speediest to take effect, whereas sublingual apomorphine offers the longest clinical effect. Inhaled levodopa has the most favorable side effect profile among the three options. An inhaled form of apomorphine is currently under development, having passed safety and efficacy studies. Each of these drugs has unique characteristics for the user, including different side effect profiles and onset of action. The best choice for a patient will depend on individual needs and circumstances. In this review, we explore those nuances to allow clinicians to select the best option for their patients.

Management of dysphagia and gastroparesis in Parkinson’s disease in real-world clinical practice – Balancing pharmacological and non-pharmacological approaches

Gastrointestinal (GI) issues are commonly experienced by patients with Parkinson’s disease (PD). Those that affect the lower GI tract, such as constipation, are the most frequently reported GI problems among patients with PD. Upper GI issues, such as swallowing dysfunction (dysphagia) and delayed gastric emptying (gastroparesis), are also common in PD but are less well recognized by both patients and clinicians and, therefore, often overlooked. These GI issues may also be perceived by the healthcare team as less of a priority than management of PD motor symptoms. However, if left untreated, both dysphagia and gastroparesis can have a significant impact on the quality of life of patients with PD and on the effectiveness on oral PD medications, with negative consequences for motor control. Holistic management of PD should therefore include timely and effective management of upper GI issues by utilizing both non-pharmacological and pharmacological approaches. This dual approach is key as many pharmacological strategies have limited efficacy in this setting, so non-pharmacological approaches are often the best option. Although a multidisciplinary approach to the management of GI issues in PD is ideal, resource constraints may mean this is not always feasible. In ‘real-world’ practice, neurologists and PD care teams often need to make initial assessments and treatment or referral recommendations for their patients with PD who are experiencing these problems. To provide guidance in these cases, this article reviews the published evidence for diagnostic and therapeutic management of dysphagia and gastroparesis, including recommendations for timely and appropriate referral to GI specialists when needed and guidance on the development of an effective management plan.

Acupuncture for Parkinson's disease: From theory to practice

Advances in molecular biology and biochemistry have improved the treatment of Parkinson's disease (PD). There has been extensive evidence on the benefit of standard treatment (e.g., deep brain stimulation, levodopa, and dopamine agonists) and acupuncture for PD. This article aims to distill the similarities and differences in the treatment concepts between Chinese and Western medicine from the perspective of reinforcing the deficiency and purging the excess, summarize the latest evidence on the benefits of acupuncture for PD from theory to practice, and propose prospective treatment options for PD.

Evaluation of Motor Complications in Parkinson's Disease: Understanding the Perception Gap between Patients and Physicians

Background

Patients with Parkinson's disease (PD) receiving levodopa treatment often report motor complications including wearing-off (WO), dyskinesia, and morning akinesia. As motor complications are associated with a decrease in patients' quality of life (QoL), it is important to identify their occurrence and commence immediate management. This study investigated whether differences in the perception of motor complications exist between patients and their physicians in routine clinical practice.

Methods

After an Internet-based screening survey, questionnaires were distributed to physicians and their patients in Japan. The 9-item Wearing-Off Questionnaire (WOQ-9) was used to objectively assess the presence of WO; patients with WOQ-9 scores ≥2 were considered to have WO. McNemar's test was used to compare physician assessment versus WOQ-9 scores, patient self-awareness versus physician assessment, and patient self-awareness versus WOQ-9, separately. Morning akinesia and dyskinesia were assessed by both physician assessment and patient self-awareness with McNemar's test. QoL was assessed using the 8-item Parkinson's Disease Questionnaire (PDQ-8) with the Wilcoxon rank-sum test.

Results

A total of 235 patients with PD and their 92 physicians participated in this survey. A significant discordance was observed between the WOQ-9 and physician assessment of WO (67.2% vs 46.0%; p < 0.0001). Furthermore, patient self-awareness of WO was 35.3% (p = 0.0004, vs physician). Morning akinesia (patient, 58.7%; physician, 48.9%; p = 0.0032), dyskinesia (patient, 34.0%; physician, 23.4%; p = 0.0006), and bodily discomfort (patient, 25.0; physician, 0.0; p = 0.0102) of QoL were underrecognized by physicians.

Conclusions

This study investigated differences in the perception of WO between patients with PD and their physicians in routine clinical practice and highlighted that patients have a low awareness of the symptoms of WO compared with physician assessments and WOQ-9. Conversely, morning akinesia, dyskinesia, and bodily discomfort were underrecognized by physicians.

Detection of Parkinson's Disease Through Automated Pupil Tracking of the Post-illumination Pupillary Response

Parkinson's disease (PD) is one of the most common neurodegenerative disorders, but it is often diagnosed after the majority of dopaminergic cells are already damaged. It is critical to develop biomarkers to identify the disease as early as possible for early intervention. PD patients appear to have an altered pupillary response consistent with an abnormality in photoreceptive retinal ganglion cells. Tracking the pupil size manually is a tedious process and offline automated systems can be prone to errors that may require intervention; for this reason in this work we describe a system for pupil size estimation with a user interface to allow rapid adjustment of parameters and extraction of pupil parameters of interest for the present study. We implemented a user-friendly system designed for clinicians to automate the process of tracking the pupil diameter to measure the post-illumination pupillary response (PIPR), permit manual corrections when needed, and continue automation after correction. Tracking was automated using a Kalman filter estimating the pupil center and diameter over time. The resulting system was tested on a PD classification task in which PD subjects are known to have similar responses for two wavelengths of light. The pupillary response is measured in the contralateral eye to two different light stimuli (470 and 610 nm) for 19 PD and 10 control subjects. The measured Net PIPR indicating different responsiveness to the wavelengths was 0.13 mm for PD subjects and 0.61 mm for control subjects, demonstrating a highly significant difference (p < 0.001). Net PIPR has the potential to be a biomarker for PD, suggesting further study to determine clinical validity.

Quantifying upper limb motor impairment in people with Parkinson's disease: a physiological profiling approach

BACKGROUND

Upper limb motor impairments, such as slowness of movement and difficulties executing sequential tasks, are common in people with Parkinson's disease (PD).

OBJECTIVE

To evaluate the validity of the upper limb Physiological Profile Assessment (PPA) as a standard clinical assessment battery in people with PD, by determining whether the tests, which encompass muscle strength, dexterity, arm stability, position sense, skin sensation and bimanual coordination can (a) distinguish people with PD from healthy controls, (b) detect differences in upper limb test domains between "off" and "on" anti-Parkinson medication states and (c) correlate with a validated measure of upper limb function.

METHODS

Thirty-four participants with PD and 68 healthy controls completed the upper limb PPA tests within a single session.

RESULTS

People with PD exhibited impaired performance across most test domains. Based on validity, reliability and feasibility, six tests (handgrip strength, finger-press reaction time, 9-hole peg test, bimanual pole test, arm stability, and shirt buttoning) were identified as key tests for the assessment of upper limb function in people with PD.

CONCLUSIONS

The upper limb PPA provides a valid, quick and simple means of quantifying specific upper limb impairments in people with PD. These findings indicate clinical assessments should prioritise tests of muscle strength, unilateral movement and dexterity, bimanual coordination, arm stability and functional tasks in people with PD as these domains are the most commonly and significantly impaired.

Findings in Chinese Patients With Parkinson's Disease: A Content Analysis From the SML Study

Social media listening (SML) is a new process for obtaining information from social media platforms to generate insights into users' experiences and has been used to analyze discussions about a multitude of diseases. To understand Parkinson's disease patients' unmet needs and optimize communication between doctors and patients, social media listening was performed to investigate concerns in Chinese patients. A comprehensive search of publicly available social media platforms with Chinese-language content posted between January 2005 and April 2019 in mainland China was performed using defined Parkinson's disease-related terms. After multiple steps of machine screening were performed, a series of posts were derived. The content was summarized and classified manually to analyze and map psychological insights, and descriptive statistics were applied to aggregate findings. A total of 101,899 patient-related posts formed the basis of this study. The topics mainly focused on motor symptoms (n = 54,983), choice of pharmaceutical drugs (n = 45,203) and non-motor symptoms (n = 44,855). The most common symptoms mentioned were tremor (54.5%), pain (22.9%), and rigidity (22.1%). Psychological burden (51%) and work/social burden (48%) were the most concerning burdens for patients and their families. The compound levodopa (43%) and dopamine agonists (23%) were the most common options for the patients, while concerns about new-generation anti-Parkinson's disease medication increased. The portraits of patients suggested varying characteristics across different periods and advocate for personalized service from doctors. In the management of patients, it is imperative to plan individualized therapy and education strategies as well as strategies for social support.

Predictors of motor complications in early Parkinson's disease: A prospective cohort study

OBJECTIVE

The objective of this study was to identify clinical predictors of motor complications (dyskinesia and motor fluctuations) of levodopa in a prospectively recruited PD cohort using longitudinal analysis.

METHODS

An inception cohort (Oxford Discovery) of 734 patients was followed to a maximum of 10 years from diagnosis using a discrete-time survival analysis. A subset analysis was used to validate an online dyskinesia-risk calculator developed from the results of the Stalevo Reduction in Dyskinesia Evaluation PD trial.

RESULTS

A total of 186 cases of dyskinesia and 254 cases of motor fluctuations were observed. Dyskinesia incidence increased with time (risk per 100 participants [95% confidence interval] 13 [11-16] <3.5 years, 16 [13-21] 3.5-5.0 years, 19 [14-26] 5-6.5 years, and 23 [16-33] >6.5 years from diagnosis). Motor complication predictors were grouped as medication predictors, disease predictors and patient predictors. Baseline nonmotor feature severity, low mood, anxiety, and age at symptom onset were associated with motor complications among a number of previously identified predictors. Replication of the Stalevo Reduction in Dyskinesia Evaluation PD calculator was reasonable with the area under the curve for dyskinesia risk score as a predictor of dyskinesia being 0.68 (95% confidence interval, 0.55-0.81).

CONCLUSIONS

This study quantifies risk of motor complications, finds consistent predictors, and demonstrates the novel finding that nonmotor features of PD, particularly low mood and anxiety, are significant risk factors for motor complications. Further validation of dyskinesia risk scores are required as well as evidence to determine if the routine use of such scores can be clinically valuable in enhancing patient care and quality of life. © 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Adenosine A2A Receptor Gene Knockout Prevents l-3,4-Dihydroxyphenylalanine-Induced Dyskinesia by Downregulation of Striatal GAD67 in 6-OHDA-Lesioned Parkinson's Mice

l-3,4-Dihydroxyphenylalanine (l-DOPA) remains the primary pharmacological agent for the symptomatic treatment of Parkinson’s disease (PD). However, the development of l-DOPA-induced dyskinesia (LID) limits the long-term use of l-DOPA for PD patients. Some data have reported that adenosine A_2A receptor (A_2AR) antagonists prevented LID in animal model of PD. However, the mechanism in which adenosine A_2AR blockade alleviates the symptoms of LID has not been fully clarified. Here, we determined to knock out (KO) the gene of A_2AR and explored the possible underlying mechanisms implicated in development of LID in a mouse model of PD. A_2AR gene KO mice were unilaterally injected into the striatum with 6-hydroxydopamine (6-OHDA) in order to damage dopamine neurons on one side of the brain. 6-OHDA-lesioned mice were then injected once daily for 21 days with l-DOPA. Abnormal involuntary movements (AIMs) were evaluated on days 3, 8, 13, and 18 after l-DOPA administration, and real-time polymerase chain reaction and immunohistochemistry for glutamic acid decarboxylase (GAD) 65 and GAD67 were performed. We found that A_2AR gene KO was effective in reducing AIM scores and accompanied with decrease of striatal GAD67, rather than GAD65. These results demonstrated that the possible mechanism involved in alleviation of AIM symptoms by A_2AR gene KO might be through reducing the expression of striatal GAD67.

Liquid levodopa-carbidopa in advanced Parkinson's disease with motor complications

While levodopa, carbidopa, ascorbic acid solution (LCAS) therapy has been used in patients with advanced Parkinson's disease (PD) for many years, long-term follow-up data is scarce. The present study aimed to determine the long-term retention rate for LCAS therapy, and to identify the causes of LCAS therapy withdrawal. Our study included a series of 38 patients with PD (14 men and 24 women) who underwent LCAS treatment between 2011 and 2013 to alleviate motor complications that were not satisfactorily controlled by optimized conventional anti-parkinsonian treatment at the Seoul National University Hospital. All patients were admitted to educate them about and initiate LCAS treatment for 2-5days, and were then followed up as outpatients. The mean follow-up duration was 12.8months, and three main reasons for LCAS treatment discontinuation were worsening of wearing-off symptoms (8 patients), persistent dyskinesia (4 patients), and poor drug adherence (4 patients). Fourteen patients (36.8%) maintained the LCAS treatment after 12months, and were categorized as the treatment-retention group. The mean percentage of on time without dyskinesia significantly increased from 33.6±17.6% to 57.0±27.7% after LCAS initiation (p=0.016) in the treatment-retention group. Twelve patients (31.6%) were still receiving LCAS treatment after 30months. LCAS treatment can be a non-device assisted therapeutic option for patients who have no access to advanced therapies such as deep brain stimulation and infusional treatments.

Clinical Assessments in Parkinson's Disease: Scales and Monitoring

Measurement of disease state is essential in both clinical practice and research in order to assess the severity and progression of a patient's disease status, effect of treatment, and alterations in other relevant factors. Parkinson's disease (PD) is a complex disorder expressed through many motor and nonmotor manifestations, which cause disabilities that can vary both gradually over time or come on suddenly. In addition, there is a wide interpatient variability making the appraisal of the many facets of this disease difficult. Two kinds of measure are used for the evaluation of PD. The first is subjective, inferential, based on rater-based interview and examination or patient self-assessment, and consist of rating scales and questionnaires. These evaluations provide estimations of conceptual, nonobservable factors (e.g., symptoms), usually scored on an ordinal scale. The second type of measure is objective, factual, based on technology-based devices capturing physical characteristics of the pathological phenomena (e.g., sensors to measure the frequency and amplitude of tremor). These instrumental evaluations furnish appraisals with real numbers on an interval scale for which a unit exists. In both categories of measures, a broad variety of tools exist. This chapter aims to present an up-to-date summary of the most relevant characteristics of the most widely used scales, questionnaires, and technological resources currently applied to the assessment of PD. The review concludes that, in our opinion: (1) no assessment methods can substitute the clinical judgment and (2) subjective and objective measures in PD complement each other, each method having strengths and weaknesses.

Intrastriatal injection of ionomycin profoundly changes motor response to l-DOPA and its underlying molecular mechanisms

Long-term l-DOPA treatment of Parkinson's disease is accompanied with fluctuations of motor responses and l-DOPA-induced dyskinesia (LID). Phosphorylation of the dopamine and c-AMP regulated phosphoprotein of 32kDa (DARPP-32) plays a role in the pathogenesis of LID, and thus dephosphorylation of this protein by activated calcineurin may help reduce LID. One important activator of calcineurin is the Ca²⁺ ionophore ionomycin. Here, we investigated whether intrastriatal injection of ionomycin to hemiparkinsonian rats produced changes in l-DOPA responses including LID. We also analyzed the effects of ionomycin on key molecular mediators of LID. Results confirmed our hypothesis that ionomycin could downregulate the phosphorylation of DARPP32 at Thr-34 and reduce LID. Besides, ionomycin decreased two established molecular markers of LID, FosB/ΔFosB and phosphorylated ERK1/2. Ionomycin also decreased the phosphorylation of three main subunits of the NMDA receptor, NR1 phosphorylated at ser896, NR2A phosphorylated at Tyr-1325, and NR2B phosphorylated at Tyr-1472. Furthermore, the anti-LID effect of striatally injected ionomycin was not accompanied by reduction of the antiparkinsonian action of l-DOPA. These data indicate that ionomycin largely interacts with striatal mechanisms that are critical to the l-DOPA motor response highlighting the role of protein dephosphorylation by calcineurin.

The recommendations of Chinese Parkinson's disease and movement disorder society consensus on therapeutic management of Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is a chronic, progressive and debilitating disease, which affects over 2.5 million people in China. PD is characterized clinically by resting tremor, muscular rigidity, bradykinesia and postural instability. As the disease progresses, additional complications can arise such as non-motor and neurobehavioral symptoms. Pharmacological treatment and surgical intervention for PD have been implemented in China. Until 10 years ago, there was lack of standardization for the management of PD in different regions and among different physicians, leading to different treatment levels in different regions and different physicians. Since then, the Chinese Parkinson's Disease and Movement Disorder Society have published three versions of guidelines for the management of PD in China, in 2006, 2009 and 2014, respectively. Correspondingly, the overall level of treatment for PD in China improved.

OBJECTIVES

To update the treatment guidelines based on current foreign and domestic practice guidelines and clinical evidence, and to improve the treatment options available to physicians in the management of PD.

SUMMARY

A variety of treatment recommendations in the treatment guidelines have been proposed, including physical activity and disease-modifying medication, which should be initiated at the early-stage of the disease. The principles of dosage titration should be followed to avoid acute adverse reactions to the drugs, to achieve a satisfactory clinical effect with a low dose and to reduce the incidence of long-term motor complications. Moreover, different treatment strategies should be considered at different stages of the disease. Importantly, treatment guidelines and personalized treatments should be valued equally. A set of treatment recommendations has been developed to assist physicians to improve and optimize clinical outcomes for patients with PD in China.

Targeting the D1-N-methyl-D-aspartate receptor complex reduces L-dopa-induced dyskinesia in 6-hydroxydopamine-lesioned Parkinson's rats

L-3,4-dihydroxyphenylalanine (l-dopa) remains the most effective therapy for Parkinson’s disease (PD), but its long-term administration is associated with the development of debilitating motor complications known as l-dopa-induced dyskinesia (LID). Enhanced function of dopamine D1 receptor (D1R) and N-methyl-d-aspartate receptor (NMDAR) is believed to participate in the pathogenesis of LID. Given the existence of physical and functional interactions between D1R and NMDAR, we explored the effects of uncoupling D1R and NMDA GluN1 (GluN1) interaction on LID by using the Tat-conjugated interfering peptide (Tat-D1-t2). In this study, we demonstrated in 6-hydroxydopamine (6-OHDA)-lesioned PD rat model that intrastriatal injection of Tat-D1-t2 alleviated dyskinetic behaviors and downregulated the phosphorylation of DARPP-32 at Thr34 induced by levodopa. Moreover, we also showed intrastriatal administration of Tat-D1-t2 elicited alterations in membranous GluN1 and D1R expression. These findings indicate that D1R/GluN1 complexes may be a molecular target with therapeutic potential for the treatment of dyskinesia in Parkinson’s patients.

Levodopa/benserazide microsphere (LBM) prevents L-dopa induced dyskinesia by inactivation of the DR1/PKA/P-tau pathway in 6-OHDA-lesioned Parkinson's rats

L-3, 4-dihydroxyphenylalanine (L-dopa) is the gold standard for symptomatic treatment of Parkinson's disease (PD), but long-term therapy is associated with the emergence of L-dopa-induced dyskinesia (LID). In the present study, L-dopa and benserazide were loaded by poly (lactic-co-glycolic acid) microspheres (LBM), which can release levodopa and benserazide in a sustained manner in order to continuous stimulate dopaminergic receptors. We investigated the role of striatal DR1/PKA/P-tau signal transduction in the molecular event underlying LID in the 6-OHDA-lesioned rat model of PD. We found that animals rendered dyskinetic by L-dopa treatment, administration of LBM prevented the severity of AIM score, as well as improvement in motor function. Moreover, we also showed L-dopa elicits profound alterations in the activity of three LID molecular markers, namely DR1/PKA/P-tau (ser396). These modifications are totally prevented by LBM treatment, a similar way to achieve continuous dopaminergic delivery (CDD). In conclusion, our experiments provided evidence that intermittent administration of L-dopa, but not continuous delivery, and DR1/PKA/p-tau (ser396) activation played a critical role in the molecular and behavioural induction of LID in 6-OHDA-lesioned rats. In addition, LBM treatment prevented the development of LID by inhibiting the expression of DR1/PKA/p-tau, as well as PPEB mRNA in dyskintic rats.

Origins and suppression of oscillations in a computational model of Parkinson's disease

Efficacy of deep brain stimulation (DBS) for motor signs of Parkinson's disease (PD) depends in part on post-operative programming of stimulus parameters. There is a need for a systematic approach to tuning parameters based on patient physiology. We used a physiologically realistic computational model of the basal ganglia network to investigate the emergence of a 34 Hz oscillation in the PD state and its optimal suppression with DBS. Discrete time transfer functions were fit to post-stimulus time histograms (PSTHs) collected in open-loop, by simulating the pharmacological block of synaptic connections, to describe the behavior of the basal ganglia nuclei. These functions were then connected to create a mean-field model of the closed-loop system, which was analyzed to determine the origin of the emergent 34 Hz pathological oscillation. This analysis determined that the oscillation could emerge from the coupling between the globus pallidus external (GPe) and subthalamic nucleus (STN). When coupled, the two resonate with each other in the PD state but not in the healthy state. By characterizing how this oscillation is affected by subthreshold DBS pulses, we hypothesize that it is possible to predict stimulus frequencies capable of suppressing this oscillation. To characterize the response to the stimulus, we developed a new method for estimating phase response curves (PRCs) from population data. Using the population PRC we were able to predict frequencies that enhance and suppress the 34 Hz pathological oscillation. This provides a systematic approach to tuning DBS frequencies and could enable closed-loop tuning of stimulation parameters.

The effects of BMY-14802 against L-DOPA- and dopamine agonist-induced dyskinesia in the hemiparkinsonian rat

RATIONALE

L-DOPA continues to be the primary treatment for patients with Parkinson's disease; however, the benefits of long-term treatment are often accompanied by debilitating side effects known as dyskinesias. In recent years, several 5-HT1A receptor agonists have been found to reduce dyskinesia in clinical and experimental models of PD. The purported sigma-1 antagonist, BMY-14802 has been previously demonstrated to reduce L-DOPA induced dyskinesia in a 5-HT1A receptor dependent manner.

OBJECTIVE

In the present study, we extend these findings by examining the anti-dyskinetic potential of BMY-14802 against L-DOPA, the D1 receptor agonist SKF81297 and the D2 receptor agonist, quinpirole, in the hemi-parkinsonian rat model. In addition, the receptor specificity of BMY-14802's effects was evaluated using WAY-100635, a 5-HT1A receptor antagonist.

RESULTS

Results confirmed the dose-dependent (20 > 10 > 5 mg/kg) anti-dyskinetic effects of BMY-14802 against L-DOPA with preservation of anti-parkinsonian efficacy at 10 mg/kg. BMY-14802 at 10 and 20 mg/kg also reduced dyskinesia induced by both D1 and D2 receptor agonists. Additionally, BMY-14802's anti-dyskinetic effects against L-DOPA, but not SKF81297 or quinpirole, were reversed by WAY-100635 (0.5 mg/kg).

CONCLUSION

Collectively, these findings demonstrate that BMY-14802 provides anti-dyskinetic relief against L-DOPA and direct DA agonist in a preclinical model of PD, acting via multiple receptor systems and supports the utility of such compounds for the improved treatment of PD.

GPi and STN deep brain stimulation can suppress dyskinesia in Parkinson's disease

OBJECTIVES

To compare subthalamic nucleus (STN) to globus pallidus internus (GPi) deep brain stimulation (DBS) for control of motor fluctuations and for potential dyskinesia-suppressing qualities.

METHODS

We conducted a retrospective database review of all patients who underwent GPi or STN DBS for idiopathic Parkinson's disease. Direct dyskinesia suppression (dDS) was defined as improvement in dyskinesia subscore of the unified Parkinson's disease rating scale (UPDRS) part IV (items 32-34), despite lack of reduction in dopaminergic medication dosage. We analyzed the data using methods appropriate for a case-control study.

RESULTS

A total of 133 patients were evaluated. At the last evaluation Dyskinesia scores and motor fluctuations significantly improved in both the GPi (p < 0.0001) and STN groups (p < 0.0001). The GPi group was more likely than the STN group to experience dDS (odds ratio = 1.95, 95% CI = 0.556, 3.21). However, the association between DBS target and dDS was not statistically significant (Pearson chi-square = 2.286, p = 0.131).

CONCLUSIONS

The overall clinical outcome of STN and GPi DBS for control of dyskinesia and motor fluctuations was similar. STN and GPi DBS both had some direct dyskinesia suppression effects.

Evaluation of blood-brain barrier transport and CNS drug metabolism in diseased and control brain after intravenous L-DOPA in a unilateral rat model of Parkinson's disease

Background

Changes in blood-brain barrier (BBB) functionality have been implicated in Parkinson's disease. This study aimed to investigate BBB transport of L-DOPA transport in conjunction with its intra-brain conversion, in both control and diseased cerebral hemispheres in the unilateral rat rotenone model of Parkinson's disease.

Methods

In Lewis rats, at 14 days after unilateral infusion of rotenone into the medial forebrain bundle, L-DOPA was administered intravenously (10, 25 or 50 mg/kg). Serial blood samples and brain striatal microdialysates were analysed for L-DOPA, and the dopamine metabolites DOPAC and HVA. Ex-vivo brain tissue was analyzed for changes in tyrosine hydroxylase staining as a biomarker for Parkinson's disease severity. Data were analysed by population pharmacokinetic analysis (NONMEM) to compare BBB transport of L-DOPA in conjunction with the conversion of L-DOPA into DOPAC and HVA, in control and diseased cerebral hemisphere.

Results

Plasma pharmacokinetics of L-DOPA could be described by a 3-compartmental model. In rotenone responders (71%), no difference in L-DOPA BBB transport was found between diseased and control cerebral hemisphere. However, in the diseased compared with the control side, basal microdialysate levels of DOPAC and HVA were substantially lower, whereas following L-DOPA administration their elimination rates were higher.

Conclusions

Parkinson's disease-like pathology, indicated by a huge reduction of tyrosine hydroxylase as well as by substantially reduced levels and higher elimination rates of DOPAC and HVA, does not result in changes in BBB transport of L-DOPA. Taking the results of this study and that of previous ones, it can be concluded that changes in BBB functionality are not a specific characteristic of Parkinson's disease, and cannot account for the decreased benefit of L-DOPA at later stages of Parkinson's disease.

Does WOQ-9 help to recognize symptoms of non-motor wearing-off in Parkinson's disease?

EWO (Epidemiology of Wearing-Off symptoms among the population of Parkinson's disease (PD) patients on L-DOPA) is a multicentric, non-interventional, epidemiological and exploratory trial, focused on patients with PD who are treated with L-DOPA. The primary objective is the estimation of wearing-off symptoms (based on WOQ-9 questionnaire and assessment by neurologists) among PD patients who are treated with L-DOPA. From September 30, 2007 to June 30, 2008 altogether 563 valid records of PD patients were collected in movement disorders centers (Level A and Level B centers). Wearing-off symptoms were observed in 66.7% of PD patients (neurologists' assessment) and in 90.6% of PD patients (WOQ-9 questionnaire). The biggest discrepancy was found in PD patients treated with L-DOPA for 0-2 years. The probability of detecting wearing-off by the neurologists strongly correlated with the highest number of positive responses in the WOQ-9 marked by PD patients. There was significant difference in the diagnosis of wearing-off between Level A centers (77.7%) and Level B centers (62.0%). When motor and non-motor symptoms in the WOQ-9 were considered, the difference between neurologists came from the detection of non-motor symptoms (lower in the Level B centers). The neurologists' assessment of wearing-off symptoms and PD patients' subjective evaluation of the WOQ-9 is based on the experience of the neurologist and on the detection of the non-motor symptoms of wearing-off. Careful explanation of the WOQ-9 questionnaire and improved awareness of the non-motor symptoms of wearing-off is strongly suggested.

Entacapone promotes cAMP-dependent colonic Cl(-) secretion in rats

BACKGROUND

Entacapone is a promising drug used widely for the treatment of Parkinson's disease (PD) as a catechol-O-methyl transferase (COMT) inhibitor. However, entacapone has gastrointestinal side effects. The aim of this study was to investigate the effects of entacapone on the epithelial ion transport in rat distal colon, and explore the underlying mechanism.

METHODS

The study was performed on freshly isolated colonic mucosa-only, submucosa-only and mucosa-submucosa preparations in rat. The short circuit current (I(SC) ) was measured to determine electrogenic ion transport, and a scanning ion-selective electrode technique (SIET) was used to directly measure Cl(-) flux across the epithelium. The content of intracellular cAMP was measured with radioimmunoassay (RIA).

KEY RESULTS

Entacapone increased mucosal I(SC) in the rat distal colon. I(SC) was inhibited significantly by apical addition of diphenylamine-2,2'-dicarboxylic acid (DPC), a blocker of the Cl(-) channel, basolateral application of bumetanide, an inhibitor of Na(+) -K(+) -2Cl(-) co-transporter (NKCC), removal of Cl(-) from the bathing solution, and pretreatment with MDL 12330A, an inhibitor of adenylate cyclase. Inhibiting endogenous prostaglandin (PG) synthesis with indomethacin, and eliminating submucosal enteric neural activity with tetrodotoxin (TTX)-inhibited entacapone-evoked I(SC) increases. Similar results were also obtained when Cl(-) flux was measured with SIET. Entacapone significantly increased intracellular cAMP content, which was greatly inhibited by either indomethacin or TTX in the tissues containing submucosal plexus, and by only indomethacin in the mucosa-only preparations.

CONCLUSIONS & INFERENCES

Entacapone stimulates cAMP-dependent Cl(-) secretion in the rat colon, and this process is regulated by endogenous PG and the submucosal enteric nervous system.

MK-801 inhibits L-DOPA-induced abnormal involuntary movements only at doses that worsen parkinsonism

Amantadine and dextromethorphan suppress levodopa (L-DOPA)-induced dyskinesia in Parkinson's disease patients and abnormal involuntary movements (AIMs) in the 6-hydroxydopamine (6-OHDA) rat model. These medications have been hypothesized to exert their therapeutic effects by a noncompetitive N-methyl-D-aspartate (NMDA) antagonist mechanism, but they also have known serotonin (5-HT) indirect agonist effects that could suppress AIMs. This raised the possibility that NMDA antagonists lacking 5-HTergic effects would not have the anti-dyskinetic action predicted by previous investigators. To test this hypothesis, we investigated MK-801, the most widely-studied NMDA antagonist. We found that chronic low-dose MK-801 (0.1 mg/kg) had no effect on development of AIMs or contraversive rotation. In addition, in L-DOPA-primed rats, low-dose MK-801 (0.1 mg/kg) had no effect on expression of AIMs, contraversive rotation, or sensorimotor function. Conversely, higher doses of MK-801 (0.2-0.3 mg/kg) suppressed expression of AIMs. However, as we show for the first time, anti-dyskinetic doses of MK-801 also suppressed L-DOPA-induced contralateral rotation and impaired sensorimotor function, likely due to non-specific interference of MK-801 with L-DOPA-induced behavior. We conclude that noncompetitive NMDA antagonists are unlikely to suppress dyskinesia clinically without worsening parkinsonism.

Potential influences of complementary therapy on motor and non-motor complications in Parkinson's disease

Nearly two-thirds of patients with Parkinson's disease (PD) use vitamins or nutritional supplements, and many more may use other complementary therapies, yet <50% of patients have discussed the use of these complementary therapies with a healthcare professional. Physicians should be aware of the complementary therapies their patients with PD are using, and the possible effects of these therapies on motor and non-motor symptoms. Complementary therapies, such as altered diet, dietary supplements, vitamin therapy, herbal supplements, caffeine, nicotine, exercise, physical therapy, massage therapy, melatonin, bright-light therapy and acupuncture, may all influence the symptoms of PD and/or the effectiveness of dopaminergic therapy. Preliminary evidence suggests complementary therapy also may influence non-motor symptoms of PD, such as respiratory disorders, gastrointestinal disorders, mood disorders, sleep and orthostatic hypotension. Whenever possible, clinicians should ensure that complementary therapy is used appropriately in PD patients without reducing the benefits of dopaminergic therapy.

The sigma-1 antagonist BMY-14802 inhibits L-DOPA-induced abnormal involuntary movements by a WAY-100635-sensitive mechanism

RATIONALE

Levodopa (L-DOPA), the gold standard treatment for Parkinson's disease (PD), eventually causes L-DOPA-induced dyskinesia (LID) in up to 80% of patients. In the 6-hydroxydopamine (6-OHDA) rat model of PD, L-DOPA induces a similar phenomenon, which has been termed abnormal involuntary movement (AIM). We previously demonstrated that BMY-14802 suppresses AIM expression in this model.

OBJECTIVES

Although BMY-14802 is widely used as a sigma-1 antagonist, it is also an agonist at serotonin (5-HT) 1A and adrenergic alpha-1 receptors. The current study was conducted to determine which of these mechanisms underlies BMY-14802's AIM-suppressing effect. This characterization included testing the 5-HT1A agonist buspirone and multiple sigma agents. When these studies implicated a 5-HT1A mechanism, we subsequently undertook a pharmacological reversal study, evaluating whether the 5-HT1A antagonist WAY-100635 counteracted BMY-14802's AIM-suppressing effects.

RESULTS

Buspirone dose-dependently suppressed AIM, supporting past findings. However, no AIM-suppressing effects were produced by drugs with effects at sigma receptors, including BD-1047, finasteride, SM-21, DTG, trans-dehydroandrosterone (DHEA), carbetapentane, and opipramol. Finally, we show for the first time that the AIM-suppressing effect of BMY-14802 was dose-dependently prevented by WAY-100635 but not by the alpha-1 antagonist prazosin.

CONCLUSIONS

BMY-14802 exerts its AIM-suppressing effects via a 5-HT1A agonist mechanism, similar to buspirone. Other 5-HT1A agonists have failed clinical trials, possibly due to submicromolar affinity at other receptors, including D2, which may exacerbate PD symptoms. BMY-14802 is a promising candidate for clinical trials due to its extremely low affinity for the D2 receptor and lack of extrapyramidal effects during prior clinical trials for schizophrenia.

Identification of zebrafish A2 adenosine receptors and expression in developing embryos

The A2A adenosine receptor (AdR) subtype has emerged as an attractive target in the pursuit of improved therapy for Parkinson's disease (PD). This report focuses on characterization of zebrafish a2 AdRs. By mining the zebrafish EST and genomic sequence databases, we identified two zebrafish a2a (adora2a.1 and adora2a.2) genes and one a2b (adora2b) AdR gene. Sequence comparisons indicate that the predicted zebrafish A2 AdR polypeptides share 62-74% amino acid identity to mammalian A2 AdRs. We mapped the adora2a.1 gene to chromosome 8, the adora2a.2 gene to chromosome 21, and the adora2b gene to chromosome 5. Whole mount in situ hybridization analysis indicates zebrafish a2 AdR genes are expressed primarily within the central nervous system (CNS). Zebrafish are known to be sensitive to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a neurotoxin that causes selective loss of dopaminergic neurons and PD-like symptoms in humans as well as in animal models. Here we show that caffeine, an A2A AdR antagonist, is neuroprotective against the adverse effects of MPTP in zebrafish embryos. These results suggest that zebrafish AdRs may serve as useful targets for testing novel therapeutic strategies for the treatment of PD.