Maladaptive plasticity at corticostriatal synapses plays an important role in the development of levodopa‐induced dyskinesia. Recently, it has been shown that synaptic plasticity is closely linked to morphologic changes of dendritic spines. To evaluate morphologic changes of dendritic spines of two types of striatal medium spiny neurons, which project to the internal segment of globus pallidus or the external segment of globus pallidus, in the levodopa‐induced dyskinesia model, we used 6‐hydroxydopamine‐lesioned rats chronically treated with levodopa. Dendritic spines were decreased and became enlarged in the direct pathway neurons of the model of levodopa‐induced dyskinesia. The same levodopa treatment to normal rats, in which no dyskinesia was observed, also induced enlargement of dendritic spines, but not a decrease in density of spines in the direct pathway neurons. These results suggest that a loss and enlargement of dendritic spines in the direct pathway neurons plays important roles in the development of levodopa‐induced dyskinesia. © 2014 International Parkinson and Movement Disorder Society

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Background. It is often difficult to differentiate Parkinson's disease (PD) from multiple system atrophy (MSA), especially in their early stages. Objectives. To examine the clinical utility of histopathological analysis of biopsied skin from the chest wall and/or leg in differentiating between the two diseases. Methods. Skin biopsies from the lower leg and/or anterior chest wall were obtained from 38 patients with idiopathic PD (26 treated with levodopa and 12 levodopa-naïve) and 13 age-matched patients with MSA. We sought aggregates of phosphorylated α-synuclein on cutaneous nerve fibers using double fluorescence immunohistochemistry and confocal microscopy and measured intraepidermal nerve fiber density (IENFD). Results. Phosphorylated α-synuclein aggregates were identified on cutaneous nerves in two patients with PD (5.3%) but in none of the patients with MSA, and IENFD was significantly lower in patients with PD when compared to those with MSA. There was no difference in IENFD between levodopa-treated and levodopa-naïve patients with PD. Conclusions. Our findings suggest that an assessment of IENFD in biopsied skin could be a useful means of differentiating between PD and MSA but that detection of α-synuclein aggregates on cutaneous nerves in the distal sites of the body is insufficiently sensitive.

We confirmed that the pain threshold was elevated in early diabetic neuropathy. We conclude that the IES electrode is a useful tool to evaluate early diabetic polyneuropathy. Muscle Nerve 54: 146-149, 2016.

IntroductionImpulse control behaviors (ICBs) are impulsive–compulsive behaviors often associated with dopamine replacement therapy in Parkinson's disease (PD). Although remission can occur in ICB, only four reports on the ratio of remission and the persistence of ICB have been published, and the associated factors with ICB remission or persistence have been little known. Therefore, we conducted a longitudinal assessment of the remission, persistence, and development of ICB and those associated factors in patients with PD.MethodsWe retrospectively investigated a PD database at Aomori Prefectural Central Hospital, Japan. One hundred and forty‐eight patients with PD who could be followed up for 2 years were enrolled. ICB was assessed using the Questionnaire for Impulsive–Compulsive Disorders in Parkinson's disease. Motor severity (Hoehn and Yahr scale and United Parkinson's Disease Rating Scale), cognitive function (Mini–Mental State Examination), and other clinical variables (sex, age, onset age, disease duration, olfactory dysfunction, and dyskinesia) and medications used to treat PD were assessed. Univariate analyses were performed.ResultsSeven patients were excluded because of the exclusion criteria, and 141 patients were analyzed. Thirty patients (21.3%) had ICB at baseline, and these patients also had significantly higher use of pergolide. The ICB remission rate was 60%, the ICB persistence ratio was 40%, and the ICB development ratio was 12.6% over 2 years. Statistically, younger age and pergolide use were associated with ICB persistence. Being male, having dyskinesia, and rotigotine, entacapone, zonisamide, and istradefylline use were associated with ICB development.ConclusionThis study suggests that younger age and pergolide use may be the new associated factors with ICB persistence and that entacapone, zonisamide, and istradefylline use may be associated with the development of ICB. Drug profiles and medication practices in Japan may explain the association of these factors with ICB.

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