Improved Sleep Correlates with Improved Quality of Life and Motor Symptoms with Foslevodopa/Foscarbidopa

BACKGROUND

Foslevodopa/foscarbidopa is a subcutaneous infusion of levodopa/carbidopa prodrugs.

OBJECTIVES

Assess correlations between sleep and efficacy from interim data of a phase 3 trial of foslevodopa/foscarbidopa (NCT03781167).

METHODS

Pearson correlations between sleep (Parkinson's Disease Sleep Scale-2 [PDSS-2]) and quality of life (QoL; Parkinson's Disease Questionnaire-39), motor experiences of daily living (m-EDL; Movement Disorder Society-Unified Parkinson's Disease Scale Part II), and "Off"/"On" times were calculated for baseline and week 26 improvements. Regression analyses were adjusted for baseline PDSS-2 score.

RESULTS

Baseline sleep correlated moderately with QoL (r = 0.44, P < 0.001) and weakly with m-EDL (r = 0.28; P < 0.001). Sleep improvement weakly correlated with improved "Off" time (r = 0.37; P < 0.001) and QoL (r = 0.36; P < 0.001). Regression analyses demonstrated significant positive associations for improved sleep, "Off" time, QoL, and m-EDL.

CONCLUSIONS

Improved sleep with foslevodopa/foscarbidopa was associated with improved QoL and "Off" time.

Continuous subcutaneous foslevodopa/foscarbidopa infusion for the treatment of motor fluctuations in Parkinson's disease: Considerations for initiation and maintenance

Background

As Parkinson's disease (PD) advances, management is challenged by an increasingly variable and inconsistent response to oral dopaminergic therapy, requiring special considerations by the provider. Continuous 24 h/day subcutaneous infusion of foslevodopa/foscarbidopa (LDp/CDp) provides steady dopaminergic stimulation that can reduce symptom fluctuation.

Objective

Our aim is to review the initiation, optimization, and maintenance of LDp/CDp therapy, identify possible challenges, and share potential mitigations.

Methods

Review available LDp/CDp clinical trial data for practical considerations regarding the management of patients during LDp/CDp therapy initiation, optimization, and maintenance based on investigator clinical trial experience.

Results

LDp/CDp initiation, optimization, and maintenance can be done without hospitalization in the clinic setting. Continuous 24 h/day LDp/CDp infusion can offer more precise symptom control than oral medications, showing improvements in motor fluctuations during both daytime and nighttime hours. Challenges include infusion-site adverse events for which early detection and prompt management may be required, as well as systemic adverse events (eg, hallucinations) that may require adjustment of the infusion rate or other interventions. A learning curve should be anticipated with initiation of therapy, and expectation setting with patients and care partners is key to successful initiation and maintenance of therapy.

Conclusion

Continuous subcutaneous infusion of LDp/CDp represents a promising therapeutic option for individuals with PD. Individualized dose optimization during both daytime and nighttime hours, coupled with patient education, and early recognition of certain adverse events (plus their appropriate management) are required for the success of this minimally invasive and highly efficacious therapy.

Continuous Subcutaneous Foslevodopa/Foscarbidopa in Parkinson's Disease: Safety and Efficacy Results From a 12-Month, Single-Arm, Open-Label, Phase 3 Study

INTRODUCTION

Foslevodopa/foscarbidopa, a soluble formulation of levodopa/carbidopa (LD/CD) prodrugs for the treatment of Parkinson's disease (PD), is administered as a 24-hour/day continuous subcutaneous infusion (CSCI) with a single infusion site. The efficacy and safety of foslevodopa/foscarbidopa versus oral immediate-release LD/CD was previously demonstrated in patients with PD in a 12-week, randomized, double-blind, phase 3 trial (NCT04380142). We report the results of a separate 52-week, open-label, phase 3 registrational trial (NCT03781167) that evaluated the safety/tolerability and efficacy of 24-hour/day foslevodopa/foscarbidopa CSCI in patients with advanced PD.

METHODS

Male and female patients with levodopa-responsive PD and ≥ 2.5 hours of "Off" time/day received 24-hour/day foslevodopa/foscarbidopa CSCI at individually optimized therapeutic doses (approximately 700-4250 mg of LD per 24 hours) for 52 weeks. The primary endpoint was safety/tolerability. Secondary endpoints included changes from baseline in normalized "Off" and "On" time, percentage of patients reporting morning akinesia, Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS), Parkinson's Disease Sleep Scale-2 (PDSS-2), 39-item Parkinson's Disease Questionnaire (PDQ-39), and EuroQol 5-dimension questionnaire (EQ-5D-5L).

RESULTS

Of 244 enrolled patients, 107 discontinued, and 137 completed treatment. Infusion site events were the most common adverse events (AEs). AEs were mostly nonserious (25.8% of patients reported serious AEs) and mild/moderate in severity. At week 52, "On" time without troublesome dyskinesia and "Off" time were improved from baseline (mean [standard deviation (SD)] change in normalized "On" time without troublesome dyskinesia, 3.8 [3.3] hours; normalized "Off" time, -3.5 [3.1] hours). The percentage of patients experiencing morning akinesia dropped from 77.7% at baseline to 27.8% at week 52. Sleep quality (PDSS-2) and quality of life (PDQ-39 and EQ-5D-5L) also improved.

CONCLUSION

Foslevodopa/foscarbidopa has the potential to provide a safe and efficacious, individualized, 24-hour/day, nonsurgical alternative for patients with PD.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov identifier NCT03781167.

Validation of the Swedish Patient-Reported Outcomes in Parkinson's Disease Scale in Outpatients

BACKGROUND

Successful treatment of Parkinson's disease (PD) requires symptom monitoring. Patient-Reported Outcomes in Parkinson's Disease (PRO-PD) is a broad scale that covers 35 motor and nonmotor symptoms, but its validation is limited.

OBJECTIVE

The aim was to validate PRO-PD in a random sample of outpatients with PD.

METHODS

Of 2123 PD patients who visited outpatient clinics in West Sweden over a 12-month period, 25% were randomly selected and invited to participate in a longitudinal observational study. Included patients were assessed at baseline, 1 year, and 3 years, with a subset also assessed at 3 to 6 months. The assessments included PRO-PD, other patient-reported scales, and Clinical Impression of Severity Index for Parkinson's Disease (CISI-PD).

RESULTS

The study included 286 PD patients. PRO-PD ratings were available from 716 (96%) of 747 study visits. All PRO-PD items exhibited positive skewness without ceiling effects. Internal consistency at baseline was excellent (Cronbach's α: 0.93). Six-month test-retest reliability was good (intraclass correlation coefficient: 0.87). Convergent validity was good, with correlation coefficients between total PRO-PD and the 8-Item Parkinson's Disease Questionnaire of 0.70, the Non-Motor Symptoms Questionnaire of 0.70, EuroQoL Five-Dimension Five-Level Scale of 0.71, and CISI-PD of 0.69. Median PRO-PD score at baseline was 995 (interquartile range: 613-1399), with a median yearly increase of 71 (interquartile range: -21 to 111). Items representing axial motor symptoms increased most over time. The minimal clinically important change in total score was 119.

CONCLUSIONS

PRO-PD was found reliable and valid for monitoring symptoms in a representative sample of outpatients with PD. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Pharmacokinetics of Intravenously (DIZ101), Subcutaneously (DIZ102), and Intestinally (LCIG) Infused Levodopa in Advanced Parkinson Disease

BACKGROUND AND OBJECTIVES

Intestinal levodopa/carbidopa gel infusion (LCIG) is superior to oral treatment in advanced Parkinson disease. The primary objective of this trial was to investigate whether continuous subcutaneous or intravenous infusion with a continuously buffered acidic levodopa/carbidopa solution yields steady-state plasma concentrations of levodopa that are equivalent in magnitude, and noninferior in variability, to those obtained with LCIG in patients with advanced Parkinson disease.

METHODS

A concentrated acidic levodopa/carbidopa (8:1) solution buffered continuously and administered intravenously (DIZ101) or subcutaneously (DIZ102) was compared with an approved LCIG in a randomized, 3-period crossover, open-label, multicenter trial. Formulations were infused for 16 hours to patients with Parkinson disease who were using LCIG as their regular treatment. Patients were recruited from several university neurology clinics but came to the same phase I unit for treatment. Pharmacokinetic variables and safety including dermal tolerance are reported. The primary outcomes were bioequivalence and noninferior variability of DIZ101 and DIZ102 vs LCIG with respect to levodopa plasma concentrations.

RESULTS

With dosing adjusted to estimated bioavailability, DIZ101 and DIZ102 produced levodopa plasma levels within standard bioequivalence limits compared with LCIG in the 18 participants who received all treatments. Although the levodopa bioavailability for DIZ102 was complete, it was 80% for LCIG. Therapeutic concentrations of levodopa were reached as quickly with subcutaneous administration of DIZ102 as with LCIG and remained stable throughout the infusions. Owing to poor uptake of LCIG, carbidopa levels in plasma were higher with DIZ101 and DIZ102 than with the former. All individuals receiving any of the treatments (n = 20) were included in the evaluation of safety and tolerability. Reactions at the infusion sites were mild and transient.

DISCUSSION

It is feasible to rapidly achieve high and stable levodopa concentrations by means of continuous buffering of a subcutaneously administered acidic levodopa/carbidopa-containing solution.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov identifier: NCT03419806. Registration first posted on February 5, 2018, first patient enrolled on February 16, 2018.

Life with Parkinson's Disease During the COVID-19 Pandemic: The Pressure Is "OFF"

People with Parkinson's disease (PwP) have been suggested to be more vulnerable to negative psychological and psycho-social effects of the COVID-19 pandemic. Our aim was to assess the potential impact of the COVID-19 pandemic in PwP. A Danish/Swedish cohort of 67 PwP was analysed. Health-related quality of life (HRQL), depression, anxiety, apathy, sleep and motor symptom-scores were included in the analysis. Additionally, the Danish participants provided free-text descriptions of life during the pandemic. Overall, the participants reported significantly better HRQL during the COVID-19 period compared with before. Reduced social pressure may be part of the explanation. Despite worsened anxiety, night sleep improved.

Activation of glucagon-like peptide-1 receptors and skilled reach foraging

Glucagon‐like peptide‐1 receptor (GLP‐1R) agonists, such as exendin‐4 (Ex4), liraglutide and dulaglutide, regulate glucose homeostasis and are thus used to treat diabetes type II. GLP‐1 also contributes towards a variety of additional physiological functions, including suppression of reward and improvement of learning. Acute activation of GLP‐1R in the nucleus accumbens (NAc) shell, an area essential for motivation, reduces the motivation to consume sucrose or alcohol when assessed in a simple motor task. However, the effects of repeated administration of the different GLP‐1R agonists on behaviours in a more complex motor task are unknown. The aim was therefore to investigate the effects of repeated Ex4, liraglutide or dulaglutide on the motivation and learning of a complex motor tasks such as skilled reach foraging in the Montoya staircase test. To explore the neurophysiological correlates of the different GLP‐1R agonists on motivation, ex vivo electrophysiological recordings were conducted. In rats with an acquired skilled reach performance, Ex4 or liraglutide but not dulaglutide reduced the motivation of skilled reach foraging. In trained rats, Ex4 infusion into NAc shell decreased this motivated behaviour, and both Ex4 and liraglutide supressed the evoked field potentials in NAc shell. In rats without prior Montoya experience, dulaglutide but not Ex4 or liraglutide enhanced the learning of skilled reach foraging. Taken together, these findings indicate that the tested GLP‐1R agonists have different behavioural outcomes depending on the context.

Apomorphine formulation may influence subcutaneous complications from continuous subcutaneous apomorphine infusion in Parkinson's disease

Continuous subcutaneous (s.c.) apomorphine infusion is an effective therapy for Parkinson’s disease (PD), but a limitation is the formation of troublesome s.c. nodules. Various chemically non-identical apomorphine formulations are available. Anecdotal experiences have suggested that shifting from one of these (Apo-Go PumpFill^®; apoGPF) to another (Apomorphine PharmSwed^®; apoPS) may influence the occurrence and severity of s.c. nodules. We, therefore, followed 15 people with advanced PD (median PD-duration, 15 years; median “off”-phase Hoehn and Yahr, IV) on apoGPF and with troublesome s.c. nodules who were switched to apoPS. Data were collected at baseline, at the time of switching, and at a median of 1, 2.5, and 7.3 months post-switch. Total nodule numbers (P < 0.001), size (P < 0.001), consistency (P < 0.001), skin changes (P = 0.058), and pain (P ≤ 0.032) improved over the observation period. PD severity and dyskinesias tended to improve and increase, respectively. Apomorphine doses were stable, but levodopa doses increased by 100 mg/day. Patient-reported apomorphine efficacy tended to increase and all participants remained on apoPS throughout the observation period; with the main patient-reported reason being improved nodules. These observations suggest that patients with s.c. nodules caused by apoGPF may benefit from switching to apoPS in terms of s.c. nodule occurrence and severity. Alternatively, observed benefits may have been due to the switch itself. As nodule formation is a limiting factor in apomorphine treatment, a controlled prospective study comparing local tolerance with different formulations is warranted.

A multiple motion sensors index for motor state quantification in Parkinson's disease

AIM

To construct a Treatment Response Index from Multiple Sensors (TRIMS) for quantification of motor state in patients with Parkinson's disease (PD) during a single levodopa dose. Another aim was to compare TRIMS to sensor indexes derived from individual motor tasks.

METHOD

Nineteen PD patients performed three motor tests including leg agility, pronation-supination movement of hands, and walking in a clinic while wearing inertial measurement unit sensors on their wrists and ankles. They performed the tests repeatedly before and after taking 150% of their individual oral levodopa-carbidopa equivalent morning dose.Three neurologists blinded to treatment status, viewed patients' videos and rated their motor symptoms, dyskinesia, overall motor state based on selected items of Unified PD Rating Scale (UPDRS) part III, Dyskinesia scale, and Treatment Response Scale (TRS). To build TRIMS, out of initially 178 extracted features from upper- and lower-limbs data, 39 features were selected by stepwise regression method and were used as input to support vector machines to be mapped to mean reference TRS scores using 10-fold cross-validation method. Test-retest reliability, responsiveness to medication, and correlation to TRS as well as other UPDRS items were evaluated for TRIMS.

RESULTS

The correlation of TRIMS with TRS was 0.93. TRIMS had good test-retest reliability (ICC = 0.83). Responsiveness of the TRIMS to medication was good compared to TRS indicating its power in capturing the treatment effects. TRIMS was highly correlated to dyskinesia (R = 0.85), bradykinesia (R = 0.84) and gait (R = 0.79) UPDRS items. Correlation of sensor index from the upper-limb to TRS was 0.89.

CONCLUSION

Using the fusion of upper- and lower-limbs sensor data to construct TRIMS provided accurate PD motor states estimation and responsive to treatment. In addition, quantification of upper-limb sensor data during walking test provided strong results.

Nicotine-induced neuroplasticity in striatum is subregion-specific and reversed by motor training on the rotarod

Nicotine is recognized as one of the most addictive drugs, which in part could be attributed to progressive neuroadaptations and rewiring of dorsal striatal circuits. Since motor‐skill learning produces neuroplasticity in the same circuits, we postulate that rotarod training could be sufficient to block nicotine‐induced rewiring and thereby prevent long‐lasting impairments of neuronal functioning. To test this hypothesis, Wistar rats were subjected to 15 days of treatment with either nicotine (0.36 mg/kg) or vehicle. After treatment, a subset of animals was trained on the rotarod. Ex vivo electrophysiology was performed 1 week after the nicotine treatment period and after up to 3 months of withdrawal to define neurophysiological transformations in circuits of the striatum and amygdala. Our data demonstrate that nicotine alters striatal neurotransmission in a distinct temporal and spatial sequence, where acute transformations are initiated in dorsomedial striatum (DMS) and nucleus accumbens (nAc) core. Following 3 months of withdrawal, synaptic plasticity in the form of endocannabinoid‐mediated long‐term depression (eCB‐LTD) is impaired in the dorsolateral striatum (DLS), and neurotransmission is altered in DLS, nAc shell, and the central nucleus of the amygdala (CeA). Training on the rotarod, performed after nicotine treatment, blocks neurophysiological transformations in striatal subregions, and prevents nicotine‐induced impairment of eCB‐LTD. These datasets suggest that nicotine‐induced rewiring of striatal circuits can be extinguished by other behaviors that induce neuroplasticity. It remains to be determined if motor‐skill training could be used to prevent escalating patterns of drug use in experienced users or facilitate the recovery from addiction.

Objective measurement in Parkinson's disease: a descriptive analysis of Parkinson's symptom scores from a large population of patients across the world using the Personal KinetiGraph®

Background

The Personal KinetiGraph® (PKG®) Movement Recording System provides continuous, objective, ambulatory movement data during routine daily activities and provides information on medication compliance, motor fluctuations, immobility, and tremor for patients with Parkinson’s disease (PD). Recent evidence has proposed targets for treatable symptoms. Indications for PKG vary by country and patient selection varies by physician.

Methods

The analyses were based upon 27,834 complete and de-identified PKGs from January 2012 to August 2018 used globally for routine clinical care. Median scores for bradykinesia (BKS) and dyskinesia (DKS) as well as percent time with tremor (PTT) and percent time immobile (PTI) were included as well as proportions of PKGs above published PKG summary score target values (BKS > 25, DKS > 9, PTT > 1%, PTI > 10%). Two sub-analyses included subjects who had 2+ PKG records and scores above proposed BKS and DKS targets, respectively, on their first PKG. Median BKS and DKS scores for subsequent PKGs (1st, 2nd, etc.) were summarized and limited to those with 100+ subsequent PKGs for each data point.

Results

Significant differences between countries were found for all 4 PKG parameter median scores (all p < 0.0001). Overall, 54% of BKS scores were > 25 and ranged from 46 to 61% by country. 10% of all DKS scores were > 9 and ranged from 5 to 15% by country. Sub-analysis for BKS showed global median BKS and DKS scores across subsequent PKGs for subjects who had 2+ PKGs and had BKS > 25 on their first PKG. There were significant changes in BKS from 1st to 2nd-6th PKGs (all p < 0.0001). Sub-analysis for DKS showed global median BKS & DKS scores across subsequent PKGs for subjects who had 2+ PKGs and had DKS > 9 on their first PKG. There were significant changes in DKS from 1st to 2nd and 3rd PKGs (both p < 0.0001).

Conclusions

This analysis shows that in every country evaluated a meaningful proportion of patients have sub-optimal PD motor symptoms and substantial variations exist across countries. Continuous objective measurement (COM) in routine care of PD enables identification and quantification of PD motor symptoms, which can be used to enhance clinical decision making, track symptoms over time and improve PD symptom scores. Thus, clinicians can use these PKG scores during routine clinical management to identify PD symptoms and work to move patients into a target range or a more controlled symptom state.

[Parkinson's disease - heterogeneous and complex in its clinical presentation]

Parkinson's disease is the second most common neurodegenerative disease. Lewy bodies with alpha-synuclein as the major component and loss of dopaminergic nerve cells in substantia nigra are neuropathological features. The diagnosis of Parkinson's disease is based on the occurrence of bradykinesia, rigidity and resting tremor. The disease is also associated with several non-motor symptoms. The therapy is mainly based on pharmacological treatment to increase dopamine signaling and neurosurgical deep brain stimulation. The symptoms and signs of the progressive disease change over time, requiring treatment adjustments. Patients should be followed by a physician, nurse and a multidisciplinary team with expertise in Parkinson's disease.

Ghrelin signalling within the rat nucleus accumbens and skilled reach foraging

Motivation alters behaviour in a complex manner and nucleus accumbens (NAc) shell has been implied as a key structure regulating such behaviour. Recent studies show that acute ghrelin signalling enhances motivation when assessed in a simple motor task. The aim of the present study was to define the role of ghrelin signalling on motivation in a more complex motor behaviour. Rats were tested in the Montoya staircase, an animal model of skilled reach foraging assessed by the number of sucrose pellets consumed. Electrophysiological recordings were conducted to explore the neurophysiological correlates of ghrelin signalling. The initial electrophysiological results displayed that ex vivo administration of ghrelin increased NAc shell output in brain slices from drug- and training-naïve rats. In rats with an acquired skilled reach performance, acute as well as repeated treatment with a ghrelin receptor (GHSR-1 A) antagonist (JMV2959) decreased the number of sucrose pellets consumed. Moreover, infusion of JMV2959 into NAc shell reduced this consumption. Sub-chronic, during ten days, JMV2959 treatment during training on the Montoya staircase reduced the number of pellets consumed, whereas ghrelin improved this behaviour. In addition, field potential and whole cell recordings were conducted in NAc shell of rats that had been treated with ghrelin or GHSR-1 A antagonist during training on the Montoya staircase. Sub-chronic administration of ghrelin during motor-skill learning selectively increased the frequency of inhibitory transmission in the NAc shell, resulting in a net suppression of accumbal output. Collectively these data suggest that ghrelin signalling in NAc shell enhances skilled reached foraging tentatively by increasing the motivation.

Acoustic white noise ameliorates reduced regional brain expression of CaMKII and ΔFosB in the spontaneously hypertensive rat model of ADHD

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ΔFosB was reduced in the DL-PFC, DLS and nAc in SH rats.

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Acoustic noise normalized ΔFosB expression in the DL-PFC and nAc of SH rats.

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CaMKII expression was reduced in the TMN in SH rats.

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Acoustic noise increased CaMKII expression in the TMN in both strains.

Loud (≥70dBA) acoustic white noise improves cognitive performance in children with ADHD as well as skilled reach and rotarod performance in the spontaneously hypertensive (SH) rat model of ADHD. To investigate how acoustic noise influences the brain activity in the SH rat model of ADHD, immunohistochemical staining of two neuronal activity and plasticity markers, Ca²⁺/Calmodulin dependent protein kinase II (CaMKII) and ΔFosB, was evaluated in Wistar (n = 24) and SH (n = 16) rats after repeated exposure to acoustic noise or ambient silence. Other SH rats (n = 6) were treated with repeated methylphenidate (MPH). Expression of CaMKII was reduced in the tuberomammillary nucleus (TMN) of the SH rat compared to Wistar but not in the nucleus accumbens (nAc) or the dorsolateral prefrontal cortex (DL-PFC). In the TMN, the expression of CaMKII was increased by noise in both strains. ΔFosB expression was reduced in nAc, DL-PFC and the dorsolateral striatum (DLS) of the SH rat compared to Wistar. Exposure to acoustic white noise significantly increased ΔFosB expression in the nAc and DL-PFC but not in the DLS of SH rats. The results indicate that acoustic noise shifts a reduced neuronal activity in the nAc, TMN and DL-PFC in SH rats toward the normal levels of activity in outbred rats. This may explain why noise has benefit selectively in ADHD.

Motion Sensor-Based Assessment of Parkinson's Disease Motor Symptoms During Leg Agility Tests: Results From Levodopa Challenge

Parkinson's disease (PD) is a degenerative, progressive disorder of the central nervous system that mainly affects motor control. The aim of this study was to develop data-driven methods and test their clinimetric properties to detect and quantify PD motor states using motion sensor data from leg agility tests. Nineteen PD patients were recruited in a levodopa single dose challenge study. PD patients performed leg agility tasks while wearing motion sensors on their lower extremities. Clinical evaluation of video recordings was performed by three movement disorder specialists who used four items from the motor section of the unified PD rating scale (UPDRS), the treatment response scale (TRS) and a dyskinesia score. Using the sensor data, spatiotemporal features were calculated and relevant features were selected by feature selection. Machine learning methods like support vector machines (SVM), decision trees, and linear regression, using ten-fold cross validation were trained to predict motor states of the patients. SVM showed the best convergence validity with correlation coefficients of 0.81 to TRS, 0.83 to UPDRS #31 (body bradykinesia and hypokinesia), 0.78 to SUMUPDRS (the sum of the UPDRS items: #26-leg agility, #27-arising from chair, and #29-gait), and 0.67 to dyskinesia. Additionally, the SVM-based scores had similar test-retest reliability in relation to clinical ratings. The SVM-based scores were less responsive to treatment effects than the clinical scores, particularly with regards to dyskinesia. In conclusion, the results from this study indicate that using motion sensors during leg agility tests may lead to valid and reliable objective measures of PD motor symptoms.

An upper body garment with integrated sensors for people with neurological disorders - early development and evaluation

Background

In neurology and rehabilitation the primary interest for using wearables is to supplement traditional patient assessment and monitoring in hospital settings with continuous data collection at home and in community settings. The aim of this project was to develop a novel wearable garment with integrated sensors designed for continuous monitoring of physiological and movement related variables to evaluate progression, tailor treatments and improve diagnosis in epilepsy, Parkinson’s disease and stroke. In this paper the early development and evaluation of a prototype designed to monitor movements and heart rate is described. An iterative development process and evaluation of an upper body garment with integrated sensors included: identification of user needs, specification of technical and garment requirements, garment development and production as well as evaluation of garment design, functionality and usability. The project is a multidisciplinary collaboration with experts from medical, engineering, textile, and material science within the wearITmed consortium. The work was organized in regular meetings, task groups and hands-on workshops. User needs were identified using results from a mixed-methods systematic review, a focus group study and expert groups. Usability was evaluated in 19 individuals (13 controls, 6 patients with Parkinson’s disease) using semi-structured interviews and qualitative content analysis.

Results

The garment was well accepted by the users regarding design and comfort, although the users were cautious about the technology and suggested improvements. All electronic components passed a washability test. The most robust data was obtained from accelerometer and gyroscope sensors while the electrodes for heart rate registration were sensitive to motion artefacts. The algorithm development within the wearITmed consortium has shown promising results.

Conclusions

The prototype was accepted by the users. Technical improvements are needed, but preliminary data indicate that the garment has potential to be used as a tool for diagnosis and treatment selection and could provide added value for monitoring seizures in epilepsy, fluctuations in PD and activity levels in stroke. Future work aims to improve the prototype further, develop algorithms, and evaluate the functionality and usability in targeted patient groups. The potential of incorporating blood pressure and heart-rate variability monitoring will also be explored.

Cerebrospinal fluid protein markers in PD patients after DBS-STN surgery-A retrospective analysis of patients that underwent surgery between 1993 and 2001

OBJECTIVE

Cerebrospinal fluid (CSF) markers of neurodegeneration [neurofilament light chain (NFL), total Tau (T-Tau)], tau pathology [phosphorylated tau (p-Tau)], glial cell damage or activation [glial fibrillary acidic protein (GFAP)], and brain amyloidosis [β-amyloid 1-42 (Aβ42)] are useful for diagnosis and prognosis in several neurodegenerative disorders. In this paper we investigate these markers and their relationship to key clinical milestones in patients with advanced Parkinson´s disease (PD) operated at our center with subthalamic nucleus deep brain stimulation (STN-DBS) for at least 15 years ago.

PATIENTS AND METHODS

Retrospective analysis of available cerebrospinal fluid and clinical data in PD-patients, 15 years or more after they underwent STN-DBS surgery. All PD-patients implanted with STN-DBS at Sahlgrenska University Hospital before January 1, 2001, were regularly assessed until January 10, 2018, or until death, or until lost to follow-up.

RESULTS

Twenty three PD patients were operated with STN-DBS. Sixteen of these (six females and ten males) underwent at least one lumbar puncture (LP) immediately prior to or after STN-DBS. Their age at the latest available LP was 64 (55-75) years [median (range)], PD duration 20 (11-33) years, and Hoehn & Yahr (H&Y) stage 3 (2-4). Time between DBS operation and the last LP was 4.5 (0.3-10.8) years. Time from the last LP to the last follow up was 6 (0.1-18) years, and for the entire cohort 115 person-years. On January 10, 2018, four PD-patients (25%) were still alive. All preoperative CSF marker levels were normal. Between two days and six months after DBS, NFL and GFAP levels increased sharply but they normalized thereafter in most patients, and were normal up to almost 11 years after neurosurgery. Over time, all patients deteriorated slowly. At the last follow up, H&Y was 5 (3-5) and 12/16 were demented. There was no significant correlation between postoperative (> 6 months) CSF NFL, GFAP, T-Tau, p-Tau, β-amyloid levels and the presence of dementia, psychosis, inability to walk or need for nursing home at the time for LP, nor for presence of dementia at the last follow up or for death as of January 10, 2018.

CONCLUSION

CSF protein biomarkers remain normal despite long PD duration, severe disability, and chronic STN-DBS. They cannot be used for PD staging or prognostication but may indicate brain damage caused by other pathological factors.

Wearables in epilepsy and Parkinson's disease-A focus group study

OBJECTIVES

Wearable sensors that measure movement and physiological variables are attractive for clinical evaluation of neurological diseases such as epilepsy and Parkinson's disease (PD). The aim of this study was to explore perceptions regarding the use of wearable technology in disease monitoring and management as reported by individuals with epilepsy and Parkinson's disease as well as health professionals working with these patient groups.

MATERIALS AND METHODS

Six patient groups (n=25) and two groups with health professionals (n=15) participated in this qualitative, descriptive study with focus group interviews. A manifest qualitative content analysis was used.

RESULTS

Four categories and nine subcategories emerged from the analysis. Participants saw possible benefits for improved treatment effect and valued this benefit more than possible inconvenience of wearing the sensors. Discrete design and simplicity were considered as facilitators for improved usability. They emphasized the importance of interactive information between patients and health professionals. However, they were concerned about unclear information and inconclusive recordings and some fears about personal integrity were at odds with the expectations on interactivity.

CONCLUSIONS

Patients need to feel well informed and find an added value in using wearables. Wearables need to be user-friendly, have an attractive design, and show clinical efficacy in improving disease management. Variations in perceptions regarding integrity, benefits, and effectiveness of monitoring indicate possible conflicts of expectations among participants. The engagement of end users, patients, and health professionals, in the design and implementation process, is crucial for the development of wearable devices that enhance and facilitate neurological rehabilitation practice.

Individualization of levodopa treatment using a microtablet dispenser and ambulatory accelerometry

AIM

This 4-week open-label observational study describes the effect of introducing a microtablet dose dispenser and adjusting doses based on objective free-living motor symptom monitoring in individuals with Parkinson's disease (PD).

METHODS

Twenty-eight outpatients with PD on stable levodopa treatment with dose intervals of ≤4 hour had their daytime doses of levodopa replaced with levodopa/carbidopa microtablets, 5/1.25 mg (LC-5) delivered from a dose dispenser device with programmable reminders. After 2 weeks, doses were adjusted based on ambulatory accelerometry and clinical monitoring.

RESULTS

Twenty-four participants completed the study per protocol. The daily levodopa dose was increased by 15% (112 mg, P < 0.001) from period 1 to 2, and the dose interval was reduced by 12% (22 minutes, P = 0.003). The treatment adherence to LC-5 was high in both periods. The MDS-UPDRS parts II and III, disease-specific quality of life (PDQ-8), wearing-off symptoms (WOQ-19), and nonmotor symptoms (NMS Quest) improved after dose titration, but the generic quality-of-life measure EQ-5D-5L did not. Blinded expert evaluation of accelerometry results demonstrated improvement in 60% of subjects and worsening in 25%.

CONCLUSIONS

The introduction of a levodopa microtablet dispenser and accelerometry aided dose adjustments improve PD symptoms and quality of life in the short term.

Cerebrospinal fluid markers of neuronal and glial cell damage in patients with autoimmune neurologic syndromes with and without underlying malignancies

Autoimmune neurologic syndromes can be paraneoplastic (associated with malignancies and/or onconeural antibodies), or non-paraneoplastic. Their clinical presentation is often similar. As prognosis is related to malignancy treatment, better biomarkers are needed to identify patients with malignancy. We investigated cerebrospinal fluid (CSF) markers of neuronal (neurofilament light chain, NFL and total tau protein, T-tau) and glial (glial fibrillary acidic protein) damage. CSF-NFL and T-tau were increased in both paraneoplastic and non-paraneoplastic autoimmune syndromes. Patients with manifest malignancies were older, had less epilepsy, more focal central and peripheral neurological signs and symptoms, and worse long-term outcome, than those without malignancy. CSF-NFL-levels predicted long-term outcome but were not diagnostic for malignancy, after age adjustment.

Levodopa/carbidopa microtablets in Parkinson's disease: a study of pharmacokinetics and blinded motor assessment

Background

Motor function assessments with rating scales in relation to the pharmacokinetics of levodopa may increase the understanding of how to individualize and fine-tune treatments.

Objectives

This study aimed to investigate the pharmacokinetic profiles of levodopa-carbidopa and the motor function following a single-dose microtablet administration in Parkinson’s disease.

Methods

This was a single-center, open-label, single-dose study in 19 patients experiencing motor fluctuations. Patients received 150% of their individual levodopa equivalent morning dose in levodopa-carbidopa microtablets. Blood samples were collected at pre-specified time points. Patients were video recorded and motor function was assessed with six UPDRS part III motor items, dyskinesia score, and the treatment response scale (TRS), rated by three blinded movement disorder specialists.

Results

AUC_0–4/dose and C_max/dose for levodopa was found to be higher in Parkinson’s disease patients compared with healthy subjects from a previous study, (p = 0.0008 and p = 0.026, respectively). The mean time to maximum improvement in sum of six UPDRS items score was 78 min (±59) (n = 16), and the mean time to TRS score maximum effect was 54 min (±51) (n = 15). Mean time to onset of dyskinesia was 41 min (±38) (n = 13).

Conclusions

In the PD population, following levodopa/carbidopa microtablet administration in fasting state, the C_max and AUC_0–4/dose were found to be higher compared with results from a previous study in young, healthy subjects. A large between subject variability in response and duration of effect was observed, highlighting the importance of a continuous and individual assessment of motor function in order to optimize treatment effect.

The Stomach-Derived Hormone Ghrelin Increases Impulsive Behavior

Impulsivity, defined as impaired decision making, is associated with many psychiatric and behavioral disorders, such as attention-deficit/hyperactivity disorder as well as eating disorders. Recent data indicate that there is a strong positive correlation between food reward behavior and impulsivity, but the mechanisms behind this relationship remain unknown. Here we hypothesize that ghrelin, an orexigenic hormone produced by the stomach and known to increase food reward behavior, also increases impulsivity. In order to assess the impact of ghrelin on impulsivity, rats were trained in three complementary tests of impulsive behavior and choice: differential reinforcement of low rate (DRL), go/no-go, and delay discounting. Ghrelin injection into the lateral ventricle increased impulsive behavior, as indicated by reduced efficiency of performance in the DRL test, and increased lever pressing during the no-go periods of the go/no-go test. Central ghrelin stimulation also increased impulsive choice, as evidenced by the reduced choice for large rewards when delivered with a delay in the delay discounting test. In order to determine whether signaling at the central ghrelin receptors is necessary for maintenance of normal levels of impulsive behavior, DRL performance was assessed following ghrelin receptor blockade with central infusion of a ghrelin receptor antagonist. Central ghrelin receptor blockade reduced impulsive behavior, as reflected by increased efficiency of performance in the DRL task. To further investigate the neurobiological substrate underlying the impulsivity effect of ghrelin, we microinjected ghrelin into the ventral tegmental area, an area harboring dopaminergic cell bodies. Ghrelin receptor stimulation within the VTA was sufficient to increase impulsive behavior. We further evaluated the impact of ghrelin on dopamine-related gene expression and dopamine turnover in brain areas key in impulsive behavior control. This study provides the first demonstration that the stomach-produced hormone ghrelin increases impulsivity and also indicates that ghrelin can change two major components of impulsivity-motor and choice impulsivity.

GLP-1 is both anxiogenic and antidepressant; divergent effects of acute and chronic GLP-1 on emotionality

Glucagon-like peptide 1 (GLP-1), produced in the intestine and hindbrain, is known for its glucoregulatory and appetite suppressing effects. GLP-1 agonists are in clinical use for treatment of type 2 diabetes and obesity. GLP-1, however, may also affect brain areas associated with emotionality regulation. Here we aimed to characterize acute and chronic impact of GLP-1 on anxiety and depression-like behavior. Rats were subjected to anxiety and depression behavior tests following acute or chronic intracerebroventricular or intra-dorsal raphe (DR) application of GLP-1 receptor agonists. Serotonin or serotonin-related genes were also measured in the amygdala, DR and the hippocampus. We demonstrate that both GLP-1 and its long lasting analog, Exendin-4, induce anxiety-like behavior in three rodent tests of this behavior: black and white box, elevated plus maze and open field test when acutely administered intraperitoneally, into the lateral ventricle, or directly into the DR. Acute central GLP-1 receptor stimulation also altered serotonin signaling in the amygdala. In contrast, chronic central administration of Exendin-4 did not alter anxiety-like behavior but significantly reduced depression-like behavior in the forced swim test. Importantly, this positive effect of Exendin-4 was not due to significant body weight loss and reduced food intake, since rats pair-fed to Exendin-4 rats did not show altered mood. Collectively we show a striking impact of central GLP-1 on emotionality and the amygdala serotonin signaling that is divergent under acute versus chronic GLP-1 activation conditions. We also find a novel role for the DR GLP-1 receptors in regulation of behavior. These results may have direct relevance to the clinic, and indicate that Exendin-4 may be especially useful for obese patients manifesting with comorbid depression.

Cerebrospinal fluid markers of neuronal and glial cell damage to monitor disease activity and predict long-term outcome in patients with autoimmune encephalitis

BACKGROUND AND PURPOSE

Clinical symptoms and long-term outcome of autoimmune encephalitis are variable. Diagnosis requires multiple investigations, and treatment strategies must be individually tailored. Better biomarkers are needed for diagnosis, to monitor disease activity and to predict long-term outcome. The value of cerebrospinal fluid (CSF) markers of neuronal [neurofilament light chain protein (NFL), and total tau protein (T-tau)] and glial cell [glial fibrillary acidic protein (GFAP)] damage in patients with autoimmune encephalitis was investigated.

METHODS

Demographic, clinical, magnetic resonance imaging, CSF and antibody-related data of 25 patients hospitalized for autoimmune encephalitis and followed for 1 year were retrospectively collected. Correlations between these data and consecutive CSF levels of NFL, T-tau and GFAP were investigated. Disability, assessed by the modified Rankin scale, was used for evaluation of disease activity and long-term outcome.

RESULTS

The acute stage of autoimmune encephalitis was accompanied by high CSF levels of NFL and T-tau, whereas normal or significantly lower levels were observed after clinical improvement 1 year later. NFL and T-tau reacted in a similar way but at different speeds, with T-tau reacting faster. CSF levels of GFAP were initially moderately increased but did not change significantly later on. Final outcome (disability at 1 year) directly correlated with CSF-NFL and CSF-GFAP levels at all time-points and with CSF-T-tau at 3 ± 1 months. This correlation remained significant after age adjustment for CSF-NFL and T-tau but not for GFAP.

CONCLUSION

In autoimmune encephalitis, CSF levels of neuronal and glial cell damage markers appear to reflect disease activity and long-term disability.

Local Change in Urinary Bladder Contractility Following CNS Dopamine Denervation in the 6-OHDA Rat Model of Parkinson's Disease

BACKGROUND

Urinary problems, including urinary frequency, urgency, and nocturia are some of the non-motor symptoms that correlate most with poor quality of life in Parkinson's disease. However, the mechanism behind these symptoms is poorly understood, in particular regarding peripheral bladder pathophysiology following dopamine degeneration.

OBJECTIVE

In this study, we compared the contractile responsiveness of urinary bladder from the 6-OHDA unilateral rat model of Parkinson's disease with that of normal untreated animals.

METHODS

The contractility of the urinary detrusor muscle was evaluated in bladder strip preparations using electrical field stimulation, and muscarinic and purinoceptor stimulations in an vitro organ bath setup.

RESULTS

Our data show that the overall contractile response following electrical field stimulation was significantly higher (43% at maximum contraction by 20-40 Hz stimulation) in the 6-OHDA-lesioned rats as compared to control animals. This increase was associated with a significant increase in the cholinergic contractile response, where the muscarinic agonist methacholine produced a 44% (at 10 -4 M concentration) higher response in the 6-OHDA-treated rats as compared to controls with a significant left-shift of the dose response. This indicates an altered sensitivity of the muscarinic receptor system following the specific central 6-OHDA-induced dopamine depletion. In addition a 36% larger contraction of strips from the 6-OHDA animals was also observed with purinoceptor activation using the agonist ATP (5×10 -3 M) during atropine treatment.

CONCLUSIONS

Our data shows that it is not only the central dopamine control of the micturition reflex that is altered in Parkinson's disease, but also the local contractile function of the urinary bladder. The current study draws attention to a mechanism of urinary dysfunction in Parkinson's disease that has previously not been described.

Effects of Stochastic Vestibular Galvanic Stimulation and LDOPA on Balance and Motor Symptoms in Patients With Parkinson's Disease

BACKGROUND

Balance problems contribute to reduced quality of life in Parkinson's disease (PD) and available treatments are often insufficient for treating axial and postural motor symptoms.

OBJECTIVE

To investigate the safety of use and possible effects of stochastic vestibular stimulation (SVS) alone and combined with LDOPA in patients with PD.

METHODS

SVS or sham stimulation was administered to 10 PD patients in a double-blind placebo controlled cross-over pilot study. Motor symptoms and balance were evaluated in a defined off-medication state and after a 200 mg test dose of LDOPA, using UPDRS-III, Posturo-Locomotor-Manual (PLM) movement times (MT), static posturography and force plate measurements of the correcting response to a balance perturbation.

RESULTS

Patients did not detect when SVS was active, but SVS increased nausea after LDOPA in two patients. Mixed model analysis demonstrated that SVS improved balance corrections after a backward perturbation and shortened the postural response time. In static posturography there was significant interaction between effects of SVS, medication and proprioceptive input (standing on foam vs. on hard support) and SVS decreased the total sway-path with eyes closed and off medication. As expected, LDOPA improved the UPDRS-III scores and MT. There was an interaction between the effect of SVS and LDOPA on UPDRS-III partly because of reduced UPDRS-III scores with SVS in the off-medication state.

CONCLUSIONS

Short term use of SVS is safe, improves corrective postural responses and may have a small positive effect on motor symptoms in PD patients off treatment.

Acoustic noise improves motor learning in spontaneously hypertensive rats, a rat model of attention deficit hyperactivity disorder

The spontaneously hypertensive (SH) rat model of ADHD displays impaired motor learning. We used this characteristic to study if the recently described acoustic noise benefit in learning in children with ADHD is also observed in the SH rat model. SH rats and a Wistar control strain were trained in skilled reach and rotarod running under either ambient noise or in 75 dBA white noise. In other animals the effect of methylphenidate (MPH) on motor learning was assessed with the same paradigms. To determine if acoustic noise influenced spontaneous motor activity, the effect of acoustic noise was also determined in the open field activity paradigm. We confirm impaired motor learning in the SH rat compared to Wistar SCA controls. Acoustic noise restored motor learning in SH rats learning the Montoya reach test and the rotarod test, but had no influence on learning in Wistar rats. Noise had no effect on open field activity in SH rats, but increased corner time in Wistar. MPH completely restored rotarod learning and performance but did not improve skilled reach in the SH rat. It is suggested that the acoustic noise benefit previously reported in children with ADHD is shared by the SH rat model of ADHD, and the effect is in the same range as that of stimulant treatment. Acoustic noise may be useful as a non-pharmacological alternative to stimulant medication in the treatment of ADHD.

Dopamine signaling in the amygdala, increased by food ingestion and GLP-1, regulates feeding behavior

Mesolimbic dopamine plays a critical role in food-related reward processing and learning. The literature focuses primarily on the nucleus accumbens as the key dopaminergic target in which enhanced dopamine signaling is associated with reward. Here, we demonstrate a novel neurobiological mechanism by which dopamine transmission in the amygdala regulates food intake and reward. We show that food intake was associated with increased dopamine turnover in the amygdala. Next, we assess the impact of direct intra-amygdala D1 and D2 receptor activation on food intake and sucrose-driven progressive ratio operant conditioning in rats. Amygdala D2 receptor activation reduced food intake and operant behavior for sucrose, whereas D2 receptor blockade increased food intake but surprisingly reduced operant behavior. In contrast, D1 receptor stimulation or blockade did not alter feeding or operant conditioning for food. The glucagon-like peptide 1 (GLP-1) system, a target for type 2 diabetes treatment, in addition to regulating glucose homeostasis, also reduces food intake. We found that central GLP-1R receptor activation is associated with elevated dopamine turnover in the amygdala, and that part of the anorexic effect of GLP-1 is mediated by D2 receptor signaling in the amygdala. Our findings indicate that amygdala dopamine signaling is activated by both food intake and the anorexic brain-gut peptide GLP-1 and that amygdala D2 receptor activation is necessary and sufficient to change feeding behavior. Collectively these studies indicate a novel mechanism by which the dopamine system affects feeding-oriented behavior at the level of the amygdala.

Can Objective Measurements Improve Treatment Outcomes in Parkinson’s Disease?

Many examples in medicine show that therapies are most effective when measurement is used to guide their implementation, dose and effects. There are effective symptomatic therapies for the motor symptoms of Parkinson’s disease, which improve quality of life and have a health economic justification for their subsidisation. As measurement should lead to more effective deployment of these therapies, even in a percentage of cases, then costs of therapy would be reduced and by that percentage. We conclude that there is a clear need or continuous objective measures of dyskinesia and bradykinesia while patients go about their normal daily activities. The benefit of measurement would be greatest if these measures were directed at treating fluctuations.

The discriminating properties of an optoelectronic movement analysis method in patients with parkinsonism

Several partly overlapping diseases have Parkinsonism as a symptom and tools that may differentiate between these disorders would be helpful. The authors evaluated the discriminating properties of the objective automated posturo-locomotor-manual (PLM) L-DOPA test in regard to health, and the movement disorders Parkinson's disease (PD), multiple system atrophy (MSA), and progressive supranuclear palsy (PSP). A PLM test-retest procedure was performed in healthy controls (n = 37) and results were compared with PLM L-DOPA tests performed by 132 patients with Parkinsonism in intermediate to advanced stages (56 PD, 53 MSA, 23 PSP). The movement time (MT) for the standardized movement and its different components was measured. The discriminating abilities of individual, or combinations of, test variables were determined by forward stepwise multiple logistic regression and evaluated with receiver-operating characteristic (ROC) analysis. Each PLM variable separated healthy persons from patients with Parkinsonism before administration of L-DOPA (area under the curve (AUC) = 0.94-0.99, p < .001 for any separate variable). A combination of (MToff - MTon)/MToff and MTon had the highest ability to separate patients with PD from patients with atypical Parkinsonism (area under the curve = 0.91, p < .001). The PLM test discriminates between healthy controls and patients with Parkinsonism, and between patients with Parkinson's disease and patients with atypical Parkinsonism.

Evaluation of the objective posturo-locomotor-manual method in patients with parkinsonian syndromes

Objective methods for quantifying patients' movement capacity would be useful in evaluating progression and interventions in neurodegenerative diseases. The Posturo-Locomotor-Manual (PLM) test is a standardized automated movement test developed to measure hypokinetic movements in patients with Parkinsonism. Our hypotheses were that the PLM movement time (MT) correlates with the Unified Parkinson's disease rating scale (UPDRS III) motor section, and that the components of the PLM test correlate with the corresponding constructed domains of UPDRS III. We also evaluated the coherence between the results of the two assessment methods after a test dose of levodopa (l-DOPA). We assessed motor function using the PLM method and UPDRS III in parallel, in the absence of medication and after administration of 200 mg l-DOPA, in 73 patients with moderate to advanced Parkinsonism: 47 with Parkinson's disease (PD), 17 with multiple system atrophy (MSA), and 9 with progressive supranuclear palsy (PSP). There was a fair correlation between the two assessment tools in the PD patients but not in the MSA or PSP patients. In the full dataset, there was a fair to good correlation between UPDRS III and the PLM MT. At group level, the UPDRS III l-DOPA test differentiated PD from MSA/PSP, whereas the PLM l-DOPA test differentiated between all three diagnoses.

Noisy galvanic vestibular stimulation promotes GABA release in the substantia nigra and improves locomotion in hemiparkinsonian rats

Background

The vestibular system is connected to spinal, cerebellar and cerebral motor control structures and can be selectively activated with external electrodes. The resulting sensation of disturbed balance can be avoided by using stochastic stimulation patterns. Adding noise to the nervous system sometimes improves function. Small clinical trials suggest that stochastic vestibular stimulation (SVS) may improve symptoms in Parkinson's disease. We have investigated this claim and possible mechanisms using the 6-hydroxydopamine (6-OHDA) hemilesion model of Parkinson's disease.

Methodology/Principal Findings

Animals were tested in the accelerating rod test and the Montoya staircase test of skilled forelimb use. In 6-OHDA hemilesioned animals, SVS improved rod performance by 56±11 s. At group level L-DOPA treatment had no effect, but positive responders improved time on rod by 60±19 s. Skilled forelimb use was not altered by SVS. To investigate how SVS may influence basal ganglia network activity, intracerebral microdialysis was employed in four regions of interest during and after SVS. In presence of the γ-amino buturic acid (GABA) transporter inhibitor NNC 711, SVS induced an increase in GABA to 150±15% of baseline in the substantia nigra (SN) of unlesioned animals, but had no effect in the pedunculopontine nucleus (PPN), the striatum or the ventromedial thalamus (VM). Dopamine release remained stable in all areas, as did GABA and amine concentrations in the SN of unstimulated controls. Following SVS, a sustained increase in GABA concentrations was observed in the ipsilesional, but not in the contralesional SN of 6-OHDA hemilesioned rats. In contrast, L-DOPA treatment produced a similar increase of GABA in the ipsi- and contra-lesional SN.

Conclusions/Significance

SVS improves rod performance in a rat model of Parkinson's disease, possibly by increasing nigral GABA release in a dopamine independent way. We propose that SVS could be useful for treating symptoms of Parkinson's disease.

Noise benefit in prepulse inhibition of the acoustic startle reflex

RATIONALE

Under some conditions, external sensory noise enhances cognitive functions, a phenomenon possibly involving stochastic resonance and/or enhanced central dopamine transmission. Prepulse inhibition (PPI) of the startle reflex is a robust measure of sensorimotor gating and can be modulated by activity in the cortex and basal ganglia, including the central dopamine pathways.

OBJECTIVES

Previous empirical studies suggest a differential effect of acoustic noise in normal children and children with attention-deficit hyperactivity disorder (ADHD). This study investigated the effect of acoustic noise on PPI and if dopamine transmission interacts with acoustic noise effects in a rat ADHD model.

METHODS

The effect of background acoustic noise on acoustic startle response and PPI were measured with a constant prepulse to background noise ratio of 9 dB(A). Spontaneously hypertensive (SH) rats were used as the ADHD model and compared with Wistar and Sprague-Dawley rats. Microdialysis, methylphenidate treatment and 6-OHDA lesions were used to investigate interaction with dopamine transmission.

RESULTS

Background noise facilitated PPI differently in SH rats and controls. The prefrontal cortex in SH rats had low basal dopamine concentrations, a high DOPAC/dopamine ratio and blunted dopamine release during PPI testing. Methylphenidate had small, but strain-specific, effects on startle and PPI. Bilateral 6-hydroxydopamine lesions did not alter startle or PPI.

CONCLUSIONS

Prefrontal dopamine transmission is altered in SH rats during the sensorimotor gating task of PPI of the acoustic startle, indicating increased dopamine reuptake in this ADHD rat model. We propose that noise benefit could be explored as a non-pharmacological alternative for treating neuropsychiatric disorders.

Rebalancing the commissural system: mechanisms of vestibular compensation

Vestibular compensation after unilateral vestibular loss is a complex, multi-factored process involving synaptic and neuronal plasticity in many areas of the brain, and it is a challenge to identify the key sites of plasticity that determine the rate and extent of behavioural recovery. Experimental evidence strongly implicates the vestibular commissural inhibitory system which links the brainstem vestibular nuclei of the two sides, both in causing the initial severe oculomotor and postural symptoms of vestibular deafferentation, and in the subsequent recovery that takes place in the early stages of compensation. Of particular interest are changes in GABAergic neurotransmission within the commissural system, and the possibility that histaminergic drugs as well as stress steroids and neurosteroids that can modulate compensation, may do so at least in part by their effects on commissural inhibition. A fuller understanding of the role of the commissural system in compensation and the effects of GABAergic neuromodulators is likely to reveal the mechanisms of action of histamine in the vestibular system and the interactions between stress, anxiety and vestibular dysfunction.

Role of the commissural inhibitory system in vestibular compensation in the rat

We investigated the role of the vestibular commissural inhibitory system in vestibular compensation (VC, the behavioural recovery that follows unilateral vestibular loss), using in vivo microdialysis to measure GABA levels in the bilateral medial vestibular nucleus (MVN) at various times after unilateral labyrinthectomy (UL). Immediately after UL, in close correlation with the appearance of the characteristic oculomotor and postural symptoms, there is a marked increase in GABA release in the ipsi-lesional MVN. This is not prevented by bilateral flocculectomy, indicating that it is due to hyperactivity of vestibular commissural inhibitory neurones. Over the following 96 h, as VC occurs and the behavioural symptoms ameliorate, the ipsi-lesional GABA levels return to near-normal. Contra-lesional GABA levels do not change significantly in the initial stages of VC, but decrease at late stages so that when static symptoms have abated there remains a significant difference between the MVNs of the two sides. We also investigated the role of the commissural inhibition in Bechterew's phenomenon, by reversibly inactivating the intact contra-lesional labyrinth in compensating animals through superfusion of local anaesthetic on the round window. Transient inactivation of the intact labyrinth elicited the lateralized behaviour described by Bechterew, but did not alter the GABA levels in either MVN, suggesting the involvement of distinct cellular mechanisms. These findings indicate that an imbalanced commissural inhibitory system is a root cause of the severe oculomotor and postural symptoms of unilateral vestibular loss, and that re-balancing of commissural inhibition occurs in parallel with the subsequent behavioural recovery during VC.

Dendritic transmitter release: a comparison of two model systems

Information flow through neurones was historically considered to be linear, with dendrites receiving information from incoming synaptic terminals, the soma processing the information and the axon carrying it to the terminal that synapses upon another cell or end organ. However, recent studies have shown that dendrites can release transmitters themselves, and thereby communicate with neighbouring structures, whether these are adjacent neurones or incoming synapses. Due to their anatomical features, the magnocellular vasopressin and oxytocin containing neurones of the hypothalamic supraoptic and paraventricular nuclei and the dopamine neurones of the substantia nigra have revealed important aspects of dendritic function including mechanisms of dendritic transmitter release.

Histaminergic and glycinergic modulation of GABA release in the vestibular nuclei of normal and labyrinthectomised rats

Vestibular compensation (the behavioural recovery that follows unilateral vestibular de-afferentation), is facilitated by histamine, and is associated with increased central histamine release and alterations in histamine H(3) receptor expression in the vestibular nuclei. However, little is known of the effects of histamine on neurotransmission in the vestibular nuclei, and the mechanisms by which histamine may influence compensation are unclear. Here we examined the modulatory effects of histaminergic agents on the release of amino acid neurotransmitters in slices of the medial vestibular nucleus (MVN) prepared from normal and labyrinthectomised rats. The release of GABA, but not glutamate, glycine or aspartate, was robustly and reproducibly evoked by a high-K(+) stimulus applied to normal MVN slices. Histamine inhibited the evoked release of GABA, both through a direct action on presynaptic H(3) receptors (presumably located on GABAergic terminals), and through a novel, indirect pathway that involved the increased release of glycine by activation of postsynaptic H(1)/H(2) receptors (presumably on glycinergic neurons). After unilateral labyrinthectomy (UL), the direct H(3) receptor-mediated inhibition of GABA release was profoundly downregulated in both ipsi-lesional and contra-lesional MVNs. This effect appeared within 25 h post-UL and persisted for at least 3 weeks post-UL. In addition, at 25 h post-UL the indirect glycinergic pathway caused a marked suppression of GABA release in the contra-lesional but not ipsi-lesional MVN, which was overcome by strychnine. Stimulation of histamine H(3) receptors at 25 h post-UL restored contra-lesional GABA release to normal, suggesting that acutely after UL H(3) receptors may strongly modulate glycinergic and GABAergic neurotransmission in the MVN. These findings are the first to demonstrate the modulatory actions of the histaminergic system on neurotransmission in the vestibular nuclei, and the changes that occur during vestibular system plasticity. During vestibular compensation, histaminergic modulation of glycine and GABA release may contribute to the rebalancing of neural activity in the vestibular nuclei of the lesioned and intact sides.

Partial depletion of dopamine in substantia nigra impairs motor performance without altering striatal dopamine neurotransmission

Previous data indicate that the release of somatodendritic dopamine in substantia nigra influences motor activity and coordination, but the relative importance of somatodendritic dopamine release vs. terminal striatal dopamine release remains to be determined. We utilized simultaneous measurement of dopamine neurotransmission by microdialysis and motor performance assessment by rotarod test to investigate the effects of local dopamine depletion in rats. The vesicular monoamine transporter inhibitor tetrabenazine (100 microm) was administered locally in substantia nigra as well as in striatum. Nigral tetrabenazine administration decreased nigral dopamine dialysate concentrations to 7% of baseline and whole-tissue dopamine content by 60%. Nigral dopamine depletion was associated with a reduction in motor performance to 73 +/- 6% of pretreatment value, but did not alter dialysate dopamine concentrations in the ipsilateral striatum. Striatal tetrabenazine administration decreased striatal dopamine dialysate concentrations to 5% of baseline and doubled the somatodendritic dopamine response to motor activity, but it was not associated with changes in motor performance or dopamine content in striatal tissue. Simultaneous treatment of substantia nigra and striatum reduced motor performance to 58 +/- 5% of the pretreatment value. The results of this study indicate that partial depletion of nigral dopamine stores can significantly impair motor functions, and that increased nigral dopamine release can counteract minor impairments of striatal dopamine transmission.

Central histaminergic modulation of vestibular function - a review

Histaminergic drugs have long been used to treat balance disorders in man, but their mechanisms of action in the vestibular system are poorly understood. In this article we review the current literature on histaminergic neurotransmission in the brain focussing particularly in the brainstem vestibular nuclei, and the role of histamine in brain plasticity during "vestibular compensation", the behavioural recovery that takes place after unilateral peripheral vestibular damage. Evidence that histaminergic compounds may facilitate vestibular compensation is reviewed, and we discuss the potential of histaminergic drugs for clinical use.

Transplantation of human embryonic stem cell-derived cells to a rat model of Parkinson's disease: effect of in vitro differentiation on graft survival and teratoma formation

Human embryonic stem cells (hESCs) have been proposed as a source of dopamine (DA) neurons for transplantation in Parkinson's disease (PD). We have investigated the effect of in vitro predifferentiation on in vivo survival and differentiation of hESCs implanted into the 6-OHDA (6-hydroxydopamine)-lesion rat model of PD. The hESCs were cocultured with PA6 cells for 16, 20, or 23 days, leading to the in vitro differentiation into DA neurons. Grafted hESC-derived cells survived well and expressed neuronal markers. However, very few exhibited a DA neuron phenotype. Reversal of lesion-induced motor deficits was not observed. Rats grafted with hESCs predifferentiated in vitro for 16 days developed severe teratomas, whereas most rats grafted with hESCs predifferentiated for 20 and 23 days remained healthy until the end of the experiment. This indicates that prolonged in vitro differentiation of hESCs is essential for preventing formation of teratomas.