Levodopa-induced dyskinesias (LID) are common and difficult to treat. This review focuses on three issues related to LID: clinical features, classification and rating, pathophysiology and pathogenesis, and management. The three primary clinical syndromes are OFF-period dystonia, peak-dose dyskinesia, and diphasic dyskinesia. Several other forms also occur, making the evaluation and choice of treatment complicated. A core component of the pathophysiology of LID is overactivity of the direct striatal output pathway. This pathway provides a direct GABAergic connection by which the striatum inhibits the output regions of the basal ganglia, i.e., the internal globus pallidus and the substantia nigra pars reticulata. Altering dopaminergic dosing and timing can abate dyskinesias, but usually impact the control of parkinsonism. Putative therapies to reduce the problem of dyskinesias could focus on the glutamatergic, GABAergic, alpha2 adrenergic, serotonergic (5HT1A, 5HT2A), opioid, histamine H3, adenosine A2A receptors, the monoamine transport or cannabinoid CB1 receptors systems. The only currently available drug with an evidence-based recommendation on efficacy for dyskinesia is amantadine. Therapy goals include the prevention of dyskinesia and treatment of dyskinesias that are troublesome clinically. New rating measures to assess severity and disability related to dyskinesia are in the process of development and clinimetric testing.

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Synaptic strength reduces during sleep, but the underlying mechanisms of this process are unclear. This study showed reduction of synaptic proteins in rat prefrontal cortex (PFC) at AM7 or Zeitgeber Time (ZT0), when the light phase or sleeping period for rats started. At this time point, microglia were weakly activated, displaying larger and more granular somata with increased CD11b expression compared with those at ZT12, as revealed by flow cytometry. Expression of opsonins, such as complements or MFG‐E8, matrix metalloproteinases, and microglial markers at ZT0 were increased compared with that at ZT12. Microglia at ZT0 phagocytosed synapses, as revealed by immunohistochemical staining. Immunoblotting detected more synapsin I in the isolated microglia at ZT0 than at ZT12. Complement C3‐ or MFG‐E8‐bound synapses were the most abundant at ZT0, some of which were phagocytosed by microglia. Systemic administration of synthetic glucocorticoid dexamethasone reduced microglial size, granularity and CD11b expression at ZT0, resembling microglia at ZT12, and increased synaptic proteins and decreased the sleeping period. Noradrenaline (NA) suppressed glutamate‐induced phagocytosis in primary cultured microglia. Systemic administration of the brain monoamine‐depleting agent reserpine decreased NA content and synapsin I expression in PFC, and increased expression of microglia markers, C3 and MFG‐E8, while increasing the sleeping period. A NA precursor l‐threo‐dihydroxyphenylserine abolished the reserpine‐induced changes. These results suggest that microglia may eliminate presumably weak synapses during every sleep phase. The circadian changes in concentrations of circulating glucocorticoids and brain NA might be correlated with the circadian changes of microglial phenotypes and synaptic strength.

Amyotrophic lateral sclerosis (ALS) is a devastating neurological disorder characterized by the degeneration of motor neurons and typically results in death within 3-5 years from onset. Familial ALS (FALS) comprises 5%-10% of ALS cases, and the identification of genes associated with FALS is indispensable to elucidating the molecular pathogenesis. We identified a Japanese family affected by late-onset, autosomal-dominant ALS in which mutations in genes known to be associated with FALS were excluded. A whole-genome sequencing and parametric linkage analysis under the assumption of an autosomal-dominant mode of inheritance with incomplete penetrance revealed the mutation c.2780G>A (p. Arg927Gln) in ERBB4. An extensive mutational analysis revealed the same mutation in a Canadian individual with familial ALS and a de novo mutation, c.3823C>T (p. Arg1275Trp), in a Japanese simplex case. These amino acid substitutions involve amino acids highly conserved among species, are predicted as probably damaging, and are located within a tyrosine kinase domain (p. Arg927Gln) or a C-terminal domain (p. Arg1275Trp), both of which mediate essential functions of ErbB4 as a receptor tyrosine kinase. Functional analysis revealed that these mutations led to a reduced autophosphorylation of ErbB4 upon neuregulin-1 (NRG-1) stimulation. Clinical presentations of the individuals with mutations were characterized by the involvement of both upper and lower motor neurons, a lack of obvious cognitive dysfunction, and relatively slow progression. This study indicates that disruption of the neuregulin-ErbB4 pathway is involved in the pathogenesis of ALS and potentially paves the way for the development of innovative therapeutic strategies such using NRGs or their agonists to upregulate ErbB4 functions.

BackgroundDyskinesias are some of the major motor complications that impair quality of life for patients with Parkinson's disease. The purpose of the present study was to investigate the efficacy of amantadine in Parkinson's disease patients suffering from dyskinesias.MethodsIn this multi-center, double-blind, randomized, placebo-controlled, cross-over trial, 36 patients with Parkinson's disease and dyskinesias were randomized, and 62 interventions, which included amantadine (300 mg /day) or placebo treatment for 27 days, were analyzed. At 15 days after washout, the treatments were crossed over. The primary outcome measure was the changes in the Rush Dyskinesia Rating Scale (RDRS) during each treatment period. The secondary outcome measures were changes in the Unified Parkinson's Disease Rating Scale part IVa (UPDRS-IVa, dyskinesias), part IVb (motor fluctuations), and part III (motor function).ResultsRDRS improved in 64% and 16% of patients treated with amantadine or placebo, respectively, with significant differences between treatments. The adjusted odds-ratio for improvement by amantadine was 6.7 (95% confidence interval, 1.4 to 31.5). UPDRS-IVa was improved to a significantly greater degree in amantadine-treated patients [mean (SD) of 1.83 (1.56)] compared with placebo-treated patients [0.03 (1.51)]. However, there were no significant effects on UPDRS-IVb or III scores.ConclusionsResults from the present study demonstrated that amantadine exhibited efficacious effects against dyskinesias in 60–70% of patients.Trial RegistrationUMIN Clinical Trial Registry UMIN000000780

Introduction: Safinamide is a reversible and selective monoamine oxidase-B (MAO-B) and sodium channel inhibitor with demonstrated efficacy in mid-to late-stage Parkinson's disease (PD) as an adjunct to L-DOPA. This study aimed to confirm the efficacy and safety of safinamide in PD patients with wearing-off. Methods: This 24-week, multicenter, randomized, double-blind, placebo-controlled, parallel-group study included Japanese PD patients with wearing-off on L-DOPA treatment. Patients were randomized to receive placebo (P), safinamide 50 mg/day (S50), or safinamide 100 mg/day (S100). The primary endpoint was the change from baseline in mean daily ON-time without troublesome dyskinesias (ON-time). Other measures included the changes in mean daily OFF-time, the unified Parkinson's disease rating scale (UPDRS) score, and the PDQ-39 summary index. Results: A total of 406 subjects were randomized, of whom 349 completed the study. Baseline characteristics were balanced. Differences in the change of mean daily ON-time at Week 24 compared with the P group were 1.39 h (p = 0.0002) in the S50 group and 1.66 h (p < 0.0001) in the S100 group. Changes from baseline in mean daily OFF-time, UPDRS Part II total score (OFF phase), UPDRS Part III total score (ON phase), and UPDRS Part I also showed significant improvements. Adverse events occurred in 58.9%, 60.2%, and 61.4% of the P, S50, and S100 groups, respectively. The most common adverse drug reactions were dyskinesias (2.1%, 8.3%, and 10.6%) and visual hallucinations (1.4%, 3.0%, and 4.5%). Conclusion: As an adjunct to L-DOPA, safinamide safely increased ON-time and improved PD symptoms/signs in PD patients with wearing-off.

Plasma procarboxypeptidase B, also known as thrombin-activatable fibrinolysis inhibitor (TAFI), is converted by thrombin into the active enzyme, carboxypeptidase B (CPB)/activated TAFI. Plasma CPB down-regulates fibrinolysis by removing carboxy-terminal lysines, the ligands for plasminogen and tissue-type plasminogen activator (tPA), from partially degraded fibrin. To target thrombosis in a new way, we have identified and optimized a phosphinic acid-containing inhibitor of CPB,heptanoic acid] and determined both the pharmacological profile and pathophysiological role of CPB in rat thrombolysis. EF6265 specifically inhibited plasma CPB activity with an IC 50 (50% inhibitory concentration) of 8.3 nM and enhanced tPA-mediated clot lysis in a concentrationdependent manner. EF6265 decreased detectable thrombi (percentage of glomerular fibrin deposition; control, 98 Ϯ 1.1; EF6265, 0.1 mg/kg, 27 Ϯ 9.1) that had been generated by tissue factor in a rat microthrombosis model with concomitant increases in plasma D-dimer concentration (control, Ͻ0.5 g/ml; EF6265, 0.1 mg/kg, 15 Ϯ 3.5 g/ml). EF6265 reduced plasma ␣2-antiplasmin activity to a lesser extent than tPA. In an arteriovenous shunt model, EF6265 (1 mg/kg) enhanced exogenous tPA-mediated thrombolysis under the same conditions that neither EF6265 nor tPA (600 kIU/kg) alone reduced thrombi. EF6265 (1 and 30 mg/kg) did not affect the bleeding time in rats. Moreover, it did not prolong the bleeding time evoked by tPA (600 kIU/kg). These results confirm that circulating procarboxypeptidase B functions as a fibrinolysis inhibitor's zymogen and validates the use of CPB inhibitors as both an enhancer of physiological fibrinolysis in microcirculation and as a novel adjunctive agent to tPA for thromboembolic diseases while maintaining a small effect on primary hemostasis.Thrombosis-related diseases, including myocardial infarction, cerebral infarction, and disseminated intravascular coagulation are life-threatening and the search for treatments remains challenging. Although thrombolytics including tissue-type plasminogen activator (tPA) or urokinase-type plasminogen activator and anticoagulants including heparin have been developed over the last few decades, the risk of hemorrhaging with these antithrombotic agents restricts their clinical use. The dose of tPA must be high enough to overcome the inhibitory effects of plasminogen activator inhibitor-1 in the plasma, and results in the generation of plasmin in circulating blood (Rijken and Sakharov, 2001). Consequently, these large quantities of generated plasmin can induce thrombolysis and result in hemorrhaging as a side effect (Bloom et al., 1988). Many efforts have therefore been made to identify and develop pharmacologically distinct antithrombotic agents while maintaining a low risk of hemorrhaging.Plasma procarboxypeptidase B (proCPB; EC 3.4.17.20), also known as thrombin-activatable fibrinolysis inhibitor (TAFI) or procarboxypeptidase U, is produced in the liver and Article, publication date, and citation informa...

Parkinson's disease (PD) symptoms do not become apparent until most dopaminergic neurons in the substantia nigra pars compacta (SNc) degenerate, suggesting that compensatory mechanisms play a role. Here, we investigated the compensatory involvement of activated microglia in the SN pars reticulata (SNr) and the globus pallidus (GP) in a 6-hydroxydopamine-induced rat hemiparkinsonism model. Activated microglia accumulated more markedly in the SNr than in the SNc in the model. The cells had enlarged somata and expressed phagocytic markers CD68 and NG2 proteoglycan in a limited region of the SNr, where synapsin I- and postsynaptic density 95-immunoreactivities were reduced. The activated microglia engulfed pre- and post-synaptic elements, including NMDA receptors into their phagosomes. Cells in the SNr and GP engulfed red fluorescent DiI that was injected into the subthalamic nucleus (STN) as an anterograde tracer. Rat primary microglia increased their phagocytic activities in response to glutamate, with increased expression of mRNA encoding phagocytosis-related factors. The synthetic glucocorticoid dexamethasone overcame the stimulating effect of glutamate. Subcutaneous single administration of dexamethasone to the PD model rats suppressed microglial activation in the SNr, resulting in aggravated motor dysfunctions, while expression of mRNA encoding glutamatergic, but not GABAergic, synaptic elements increased. These findings suggest that microglia in the SNr and GP become activated and selectively eliminate glutamatergic synapses from the STN in response to increased glutamatergic activity. Thus, microglia may be involved in a negative feedback loop in the indirect pathway of the basal ganglia to compensate for the loss of dopaminergic neurons in PD brains.