Time course of striatal DeltaFosB-like immunoreactivity and prodynorphin mRNA levels after discontinuation of chronic dopaminomimetic treatment.

DFosB-like proteins are particularly stable transcription factors that accumulate in the brain in response to chronic perturbations. In this study we have compared the time-course of striatal FosB/DFosB-like immunoreactivity and prodynorphin mRNA expression after discontinuation of chronic cocaine treatment to intact rats and chronic L-DOPA treatment to unilaterally 6-hydroxydopamine (6-OHDA) lesioned rats. The animals were killed between 3 h and 16 days after the last drug injection. In both treatment paradigms, the druginduced FosB/DFosB immunoreactivity remained significantly elevated in the caudate putamen even at the longest withdrawal period examined. The concomitant upregulation of prodynorphin mRNA, a target of DFosB, paralleled the time-course of DFosB-like immunoreactivity in the 6-OHDA-lesion/L-DOPA model, but was more transient in animals treated with cocaine. These results suggest that DFosB-like proteins have exceptional in vivo stability. In the dopamine-denervated striatum, these proteins may exert sustained effects on the expression of their target genes long after discontinuation of L-DOPA pharmacotherapy

Cell type-specific plasticity of striatal projection neurons in parkinsonism and L-DOPA-induced dyskinesia

The striatum is widely viewed as the fulcrum of pathophysiology in Parkinson’s disease (PD) and L-DOPA-induced dyskinesia (LID). In these disease states, the balance in activity of striatal direct pathway spiny projection neurons (dSPNs) and indirect pathway spiny projection neurons (iSPNs) is disrupted, leading to aberrant action selection. However, it is unclear whether countervailing mechanisms are engaged in these states. Here we report that iSPN intrinsic excitability and excitatory corticostriatal synaptic connectivity were lower in PD models than normal; ​L-DOPA treatment restored these properties. Conversely, dSPN intrinsic excitability was elevated in tissue from PD models and suppressed in LID models. Although the synaptic connectivity of dSPNs did not change in PD models, it fell with ​L-DOPA treatment. In neither case, however, was the strength of corticostriatal connections globally scaled. Thus, SPNs manifested homeostatic adaptations in intrinsic excitability and in the number but not strength of excitatory corticostriatal synapses

Pathophysiology of L-dopa-induced motor and non-motor complications in Parkinson's disease

Involuntary movements, or dyskinesia, represent a debilitating complication of levodopa (L-dopa) therapy for Parkinson's disease (PD). L-dopa-induced dyskinesia (LID) are ultimately experienced by the vast majority of patients. In addition, psychiatric conditions often manifested as compulsive behaviours, are emerging as a serious problem in the management of L-dopa therapy. The present review attempts to provide an overview of our current understanding of dyskinesia and other L-dopa-induced dysfunctions, a field that dramatically evolved in the past twenty years. In view of the extensive literature on LID, there appeared a critical need to re-frame the concepts, to highlight the most suitable models, to review the central nervous system (CNS) circuitry that may be involved, and to propose a pathophysiological framework was timely and necessary. An updated review to clarify our understanding of LID and other L-dopa-related side effects was therefore timely and necessary. This review should help in the development of novel therapeutic strategies aimed at preventing the generation of dyskinetic symptoms

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

Measurement of the very rare K+→π+ννˉK^+ \to \pi^+ \nu \bar\nu decay

The decay K+→π+νν¯ , with a very precisely predicted branching ratio of less than 10−10 , is among the best processes to reveal indirect effects of new physics. The NA62 experiment at CERN SPS is designed to study the K+→π+νν¯ decay and to measure its branching ratio using a decay-in-flight technique. NA62 took data in 2016, 2017 and 2018, reaching the sensitivity of the Standard Model for the K+→π+νν¯ decay by the analysis of the 2016 and 2017 data, and providing the most precise measurement of the branching ratio to date by the analysis of the 2018 data. This measurement is also used to set limits on BR(K+→π+X ), where X is a scalar or pseudo-scalar particle. The final result of the BR(K+→π+νν¯ ) measurement and its interpretation in terms of the K+→π+X decay from the analysis of the full 2016-2018 data set is presented, and future plans and prospects are reviewed

Investigating the molecular mechanisms of L-DOPA-induced dyskinesia in the mouse

L-DOPA-induced dyskinesia (LID) is a major complication of the pharmacotherapy of Parkinson's disease (PD). Animal models of LID are essential for investigating pathogenic pathways and therapeutic targets. While non-human primates have been the preferred species for pathophysiological studies, mouse models of LID have been recently produced and characterized to facilitate molecular investigations. Most of these studies have used mice with unilateral 6-hydroxydopamine (6-OHDA) lesions of the nigrostriatal projection sustaining treatment with L-DOPA for 1-4 weeks. Mice with complete medial forebrain bundle lesions have been found to develop dyskinetic movements of maximal severity associated with a pronounced post-synaptic supersensitivity of D1-receptor dependent signaling pathways throughout the striatum. In contrast, mice with striatal 6-OHDA lesions have been found to exhibit a variable susceptibility to LID and a regionally restricted post-synaptic supersensitivity. Genetic mouse models of PD have just started to be used for studies of LID, providing an opportunity to dissect the impact of genetic factors on the maladaptive neuroplasticity that drives the development of treatment-induced involuntary movements in PD

Oral and infusion levodopa therapy in the management of Parkinson’s disease

Introduction: The clinical diagnosis of Parkinson’s disease (PD) is based on the identification of bradykinesia and at least one additional feature among rigidity, resting tremor and postural instability. These clinical features have been estimated to appear when at least 50% of the nigral dopamine neurons and 70% of putaminal dopamine tissue contents are lost [1]. Dopaminergic imaging suggests that at least 30% of the dopamine storage capacity (measured by 18 F-DOPA uptake) and 50% of putamen dopamine transporters have been lost by the onset of contralateral limb bradykinesia and rigidity [2]. In addition to the above motor symptoms, a number of nonmotor symptoms are associated with PD. These include gastrointestinal, cardiovascular, urological and psychiatric symptoms, as well as problems with vision, pain and sleep [3]. There is general agreement that the typical motor features of PD depend on putaminal dopamine depletion. Indeed, these features respond well to dopaminergic treatments, the most effective being levodopa (l-DOPA), a dopamine precursor that can cross the blood-brain barrier. Treatment with levodopa contributes significantly to improvements in the quality of life of people with PD and increases their expected life length (reviewed in [4]). Moreover, treatment with peroral levodopa is relatively well tolerated and inexpensive [5]. Many of nonmotor symptoms may also respond to levodopa treatment [3]. Because of the above reasons, levodopa is currently considered the “gold standard” for the symptomatic treatment of PD [4, 5]. However, the response to levodopa changes with disease progression, becoming complicated by motor fluctuations and dyskinesias in a majority of patients within a few years. As will be discussed below, these motor complications can become disabling, calling for a reduction in oral levodopa dosage and/or for its replacement with advanced invasive treatments. Moreover, levodopa is poorly effective against clinical features that mainly depend on the degeneration of nondopaminergic systems. These include some nonmotor symptoms as well as motor features that occur in advanced disease stages, such as freezing of gait and falls [6]. In this chapter, we will review the history of levodopa pharmacotherapy in PD, the complications of this therapy, the options currently available to optimize oral treatment with levodopa, and recent advances in developing methods for a more continuous levodopa delivery