Effect of daily light exposure on sleep in polar regions: A meta-analysis.

Although studies have shown that light affects sleep in polar populations, the sample size of most studies is small. This meta-analysis provides the first systematic review of the effects of summer glare, spring and fall moderate daylight, and artificial lighting on general sleep problems (sleep duration, efficiency, and delay). This analysis included 18 studies involving 986 participants. We calculated the random effect size via an evidence-based meta-analysis that analysed the effect of bright/auxiliary light on sleep and the effect of three different types of light on sleep compared with conventional light. There was no significant correlation between specific light types and sleep duration. Intense summer light has a negative effect on sleep time and efficiency. Moderate, natural light in spring and autumn effectively delayed sleep but could not improve sleep efficiency. For artificial fill light, neither blue light nor enhanced white light has been found to have a significant effect. In summary, summer light has a detrimental effect on sleep in polar populations, and moderate natural light may be superior to conventional light. However, specific strategies to improve sleep and artificial lighting in polar populations must be explored further.

An observational clinical and video-polysomnographic study of the effects of rotigotine in sleep disorder in Parkinson's disease.

PURPOSE: Sleep disturbance is common in Parkinson's disease (PD) and negatively impacts quality of life. There is little data on how dopamine agonists influence nocturnal sleep in PD, particularly in sleep laboratory data to measure sleep parameters and their changes objectively. The goal of this open-label study was to objectively evaluate the effect of rotigotine on sleep in PD patients by video-polysomnographic methods. METHODS: A total of 25 PD patients with complaints of nocturnal sleep impairment were enrolled. The sleep quality before and after stable rotigotine therapy was evaluated subjectively through questionnaire assessments and objectively measured by video-polysomnographic methods. The Parkinsonism, depression, anxiety, and quality of life of PD patients were also evaluated through questionnaire assessments. RESULTS: At the end of rotigotine treatment, the PD daytime functioning, motor performance, depression, subjective quality of sleep, and the quality of life improved. Video-polysomnographic analysis showed that the sleep efficiency and stage N1% were increased, while the sleep latency, wake after sleep onset, and the periodic leg movements in sleep index were decreased after rotigotine treatment. CONCLUSIONS: Video-polysomnographic analysis confirmed the subjective improvement of sleep after rotigotine treatment. This observation suggests that in PD rotigotine is a treatment option for patients complaining from sleep disturbances.

Trehalose inhibits fibrillation of A53T mutant alpha-synuclein and disaggregates existing fibrils.

The aggregation of alpha-synuclein (AS) is pivotally implicated in the development of Parkinson's disease (PD), inhibiting this process might be effective in treating PD. Here, by using circular dichroism spectroscopy, thioflavin T fluorescence, and atomic force microscopy, we found that trehalose at low concentration disaggregates preformed A53T AS protofibrils and fibrils into small aggregates or even random coil structure, while trehalose at high concentration slows down the structural transition into ß-sheet structure and completely prevents the formation of mature A53T AS fibrils. Further work in vivo will be needed to evaluate its potential as a novel strategy for treating PD.

Effect of trehalose on PC12 cells overexpressing wild-type or A53T mutant α-synuclein.

Accumulation of α-synuclein (α-Syn) is a common pathology for both familiar and sporadic Parkinson's disease (PD), enhancing its clearance might be a promising strategy for treating PD. To assess the potential of trehalose in this regard, we investigated its effect on the PC12 cells overexpressing wild type (WT) or A53T mutant α-Syn and the implicated pathway it might mediated. We observed that trehalose promoted the clearance of A53T α-Syn but not WT α-Syn in PC12 cells, and confirmed the increased LC3 and Lysotracker RED positive autolysosomes by using lysotracker and LC3 staining, the enhanced expression of LC3-II in Western blot, and more autophagosomes under Transmission Electron Microscope in a dose dependent manner after the trehalose treatment. The activation of autophagy can be alleviated by applying macroautophagy inhibitor 3-methyladenine (3-MA). In addition, degradation of A53T and WT α-Syn was blocked after Ubiquitin Proteasome System (UPS) inhibitor (MG132) was applied in those PC12 cells overexpressing A53T or WT α-Syn, suggesting that A53T α-Syn could be degraded by both UPS and macroautophagy. But the effect of trehalose on A53T α-Syn is mainly mediated through the macroautophagy pathway, which is not a dominant way for WT α-Syn clearance. Further in vivo research will be needed to verify the effectiveness of trehalose in treating PD.

Inhibition of evoked glutamate release by neurosteroid allopregnanolone via inhibition of L-type calcium channels in rat medial prefrontal cortex.

Allopregnanolone is one of the most important neurosteroids in the brain. We studied the effect and mechanism of allopregnanolone on spontaneous and evoked glutamate release in the medial prefrontal cortex using electrophysiological and biochemical methods combined with pharmacological approaches. The results showed that allopregnanolone had no effects on the frequency of miniature excitatory postsynaptic current (mEPSCs), but inhibited the depolarizing agent veratridine-evoked increase in the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) and inhibited the first of the two responses evoked by a pair of electrical pulses more effectively than the second, resulting in increased paired-pulse facilitation (PPF) and thus suggesting a presynaptic inhibitory effect on electrical pulse-evoked glutamate release. A similar effect was also obtained for the effect of allopregnanolone on protein kinase A (PKA) activation, an upstream event of presynaptic glutamate release. Interestingly, allopregnanolone had none of these effects in the striatum. In the study of the upstream mechanism of the PKA inhibition by allopregnanolone, we found that allopregnanolone inhibited extracellular calcium influx-evoked PKA activation, but had no effects on intracellular calcium store release-evoked PKA activation; L-type calcium channel antagonists, but not N- and P/Q-type calcium channel antagonist, blocked the effect of allopregnanolone; allopregnanolone inhibited L-type calcium channel agonist-evoked increase in the PKA activity, intrasynaptosomal calcium concentration and frequency of sEPSCs. These results suggest that allopregnanolone inhibits evoked glutamate release via the inhibition of L-type calcium channels in the medial prefrontal cortex, but does not in the striatum.

Effects of Rotigotine on REM Sleep Behavior Disorder in Parkinson Disease.

STUDY OBJECTIVES: REM sleep behavior disorder (RBD) is a common manifestation of Parkinson disease (PD). In this study, we assessed the effects of rotigotine transdermal patch on RBD features in patients with PD. METHODS: In this prospective open-label study, eleven PD patients with untreated RBD were administered rotigotine patches for up to seven months to ameliorate their parkinsonism. The severities of their RBD symptoms before and after rotigotine therapy were evaluated through patient and bed partner interviews, a validated evaluation scale (REM sleep behavior disorder questionnaire-Hong Kong, RBDQ-HK), and blinded assessments based on video-polysomnographic (VPSG) measure. RESULTS: Rotigotine improved parkinsonism and subjective sleep quality in PD patients with RBD. The RBDQ-HK total score, especially the Factor 2 score, was decreased, which demonstrated that the subjective severity of RBD symptoms was improved after rotigotine treatment, especially the frequency and severity of abnormal RBD-related motor behaviors. The VPSG analyses showed that the total sleep time (TST) and stage 1% were increased and that the PLMS index was decreased. However, no differences in the RBD-related sleep measures were observed. CONCLUSIONS: The improved RBD symptoms and VPSG measures of PD patients in this study (TST, stage 1%, and PLMS index) suggest that, in PD, rotigotine may partially improve RBD-related symptoms. Rotigotine should be considered to be an optional drug for the treatment of RBD symptoms in PD.

Proteasome inhibitor-induced autophagy in PC12 cells overexpressing A53T mutant α-synuclein.

The aim of the present study was to examine the effects of proteasome inhibitor (PI)­induced autophagy on PC12 cells overexpressing A53T mutant α­synuclein (α­syn) by detecting alterations in the levels of microtubule­associated protein 1A/1B light chain (LC3)+ autophagosomes and the lysotracker­positive autolysosomes using immunofluorescence, the expression of LC3­II using western blot analysis and the morphology of PC12 cells using transmission electron microscopy. It was found that the addition of MG132 (500 nmol/l) significantly increased the number of autophagosomes and autolysosomes and upregulated the expression of LC3­II. The autophagy inhibitor 3­methyladenine (3­MA) completely inhibited the autophagy induced by MG132 (500 nmol/l). The autophagy enhancer trehalose significantly increased the number of autophagosomes and autolysosomes and improved the protein level of LC3­II induced by MG132. To examine the effect of PI­induced autophagy on the degradation of A53T mutant α­syn, the expression of α­syn was detected by western blot analysis. It was revealed that MG132 increased the expression of A53T α­syn and trehalose counteracted the increase of A53T α­syn induced by MG132. Combined inhibition of 3­MA and PI significantly increased the accumulation of A53T α­syn as compared with treatment using either single agent. In addition, combination of MG132 (500 nmol/l) with trehalose (50 mmol/l) or 3­MA (2 mmol/l) markedly decreased the cell viability as compared with treatment using either single agent individually as demonstrated using a 3­(4,5­dimethylthiazol­2­yl)­2,5­diphenyltetrazolium bromide assay. These results suggest that the PI, MG132, could induce autophagy in PC12 cells overexpressing A53T mutant α­syn and this autophagy could be completely inhibited by 3­MA, indicating that PI­induced autophagy is mediated by the upregulation of the macroautophagy class III PI3K pathway. PI­induced autophagy may act as a compensatory degradation system for degradation of A53T α­syn when the ubiquitin­proteasome system is impaired. Autophagy activation may directly contribute to the survival of PC12 cells treated with proteasome inhibitors. The present study may assist in illuminating the association between PI and autophagy in the pathogenesis of Parkinson's disease.

Neurosteroid dehydroepiandrosterone sulphate inhibits persistent sodium currents in rat medial prefrontal cortex via activation of sigma-1 receptors.

Dehydroepiandrosterone sulphate is one of the most important neurosteroids. In the present paper, we studied the effect of dehydroepiandrosterone sulphate on persistent sodium currents and its mechanism and functional consequence with whole-cell patch clamp recording method combined with a pharmacological approach in the rat medial prefrontal cortex slices. The results showed that dehydroepiandrosterone sulphate inhibited the amplitude of persistent sodium currents and the inhibitory effect was significant at 0.1 microM, reached maximum at 1 microM and decreased with the increase in the concentrations of above 1 microM. The effect of dehydroepiandrosterone sulphate on persistent sodium currents was canceled by the Gi protein inhibitor and the protein kinase C inhibitor, but not by the protein kinase A inhibitor. The effect of dehydroepiandrosterone sulphate on persistent sodium currents was also canceled by the sigma-1 receptor blockers and the sigma-1 receptor agonist could mimic the effect of dehydroepiandrosterone sulphate. Dehydroepiandrosterone sulphate had no significant influence on neuronal excitability but could significantly inhibit chemical inhibition of mitochondria-evoked increase in persistent sodium currents. These results suggest that dehydroepiandrosterone sulphate inhibits persistent sodium currents via the activation of sigma-1 receptors-Gi protein-protein kinase C-coupled signaling pathway, and the main functional consequence of this effect of DHEAS is presumably to protect neurons under ischemia.