Recent advances in the pathology of prodromal non-motor symptoms olfactory deficit and depression in Parkinson's disease: clues to early diagnosis and effective treatment

Microglial gp91phox-mediated neuroinflammation and ferroptosis contributes to learning and memory deficits in rotenone-treated mice

Apart from dopaminergic neurotoxicity, exposure to rotenone, a commonly used insecticide in agriculture, also adversely affects hippocampal and cortical neurons, resulting in cognitive impairments in mice. We recently established a role of microglia-mediated neuroinflammation in rotenone-elicited deficits of cognition, yet the mechanisms remain elusive. Here, we investigated the involvement of NADPH oxidase 2 (NOX2) catalytic subunit gp91phox in rotenone-induced cognitive deficits and the associated mechanisms. Our study demonstrated that rotenone exposure elevated expression of gp91phox and phosphorylation of the NOX2 cytosolic subunit p47phox, along with NADPH depletion in the hippocampus and cortex of mice, indicating NOX2 activation. Specific knockdown of gp91phox in microglia via adeno-associated virus delivery resulted in reduced microglial activation, proinflammatory gene expression and improved learning and memory capacity in rotenone-intoxicated mice. Genetic deletion of gp91phox also reversed rotenone-elicited cognitive dysfunction in mice. Furthermore, microglial gp91phox knockdown attenuated neuronal damage and synaptic loss in mice. This intervention also suppressed iron accumulation, disruption of iron-metabolism proteins and iron-dependent lipid peroxidation and restored the balance of ferroptosis-related parameters, including GPX4, SLC711, PTGS2, and ACSL4 in rotenone-lesioned mice. Intriguingly, pharmacological inhibition of ferroptosis with liproxstatin-1 conferred protection against rotenone-induced neurodegeneration and cognitive dysfunction in mice. In summary, our findings underscored the contribution of microglial gp91phox-dependent neuroinflammation and ferroptosis to learning and memory dysfunction in rotenone-lesioned mice. These results provided valuable insights into the pathogenesis of cognitive deficits associated with pesticide-induced Parkinsonism, suggesting potential therapeutic avenues for intervention.

Emerging autophagic endo-lysosomal targets in the management of Parkinson's disease

Synucleopathies, specifically Parkinson's disease, are still incurable and available therapeutic options are scarce and symptomatic. The autophagy-lysosomal-endosomal system is an indigenous mechanism to manage the proteome. Excess/misfolded protein accumulation activates this system, which degrades the undesired proteins via lysosomes. Cells also eliminate these proteins by releasing them into the extracellular space via exosomes. However, the sutophagy-lysosomal-endosomal system becomes unfunctional in Parkinson's disease and there is accumulation and spread of pathogenic alpha-synuclein. Neuronal degeneration results Owing to pathogenic alpha-synuclein. Thus, the autophagy-lysosomal-endosomal system could be a promising target for neuroprotection. In the present review, we discuss the autophagy-lysosomal-endosomal system as an emerging target for the management of Parkinson's disease. Modulation of these targets associated with the autophagy-lysosomal-endosomal system can aid in clearing pathogenic alpha-synuclein and prevent the degeneration of neurons.

Olfactory Dysfunction and Glaucoma

BACKGROUND

Olfactory dysfunction is a well-known phenomenon in neurological diseases with anosmia and hyposmia serving as clinical or preclinical indicators of Alzheimer's disease, Parkinson's disease, and other neurodegenerative disorders. Since glaucoma is a neurodegenerative disease of the visual system, it may also entail alterations in olfactory function, warranting investigation into potential sensory interconnections.

METHODS

A review of the current literature of the last 15 years (from 1 April 2008 to 1 April 2023) was conducted by two different authors searching for topics related to olfaction and glaucoma.

RESULTS

three papers met the selection criteria. According to these findings, patients with POAG appear to have worse olfaction than healthy subjects. Furthermore, certain predisposing conditions to glaucoma, such as pseudoexfoliation syndrome and primary vascular dysregulation, could possibly induce olfactory changes that can be measured with the Sniffin Stick test.

CONCLUSIONS

the scientific literature on this topic is very limited, and the pathogenesis of olfactory changes in glaucoma is not clear. However, if the results of these studies are confirmed by further research, olfactory testing may be a non-invasive tool to assist clinicians in the early diagnosis of glaucoma.

Depression is associated with the nonmotor symptoms of Parkinson's disease: A comparative analysis

Background and aims

The nonmotor symptoms (NMS) of Parkinson's disease (PD) and their potential role in early diagnosis are recent debates. Herein, we aimed to investigate the association between depression and NMS of PD including sleep disorders, hyposexuality, hyposmia, constipation, and orthostatic hypotension.

Methods

A total of 93 PD patients with depression and 67 PD patients without depression were included in the study, and NMS were compared between the two groups. Furthermore, the possible associations between depression severity measured by Beck Depression Inventory (BDI) and NMS were investigated using linear regression or binary logistic regression models controlled for possible confounders. Eventually, we performed a subgroup analysis in each mild, moderate, and severe depression group.

Results

Orthostatic hypotension, constipation, and hyposexuality showed a significant difference between PD patients with and without depression (p < 0.001, p = 0.029, and p < 0.001, respectively). The BDI score was significantly associated with hyposexuality, Montreal cognitive assessment (MoCA), and Pittsburgh Sleep Quality (p = 0.016, p = 0.010, and p = 0.011, respectively); however, after adjustments for possible confounders, the associations of the BDI score with the MoCA score and hyposexuality remained significant (p = 0.015 and p = 0.019, respectively). Considering subgroup analysis, a similar pattern of significant results was observed particularly in the severe group.

Conclusions

This study suggests a possible association between depression in PD patients and some NMS observed in the course of PD. These findings could be beneficial for early diagnosis of the disease, which eventually could make a considerable difference in the management of PD patients. Additional interventional longitudinal studies are warranted to explore how controlling depression could impact the NMS of patients with PD.

A liquid crystal in situ gel based on rotigotine for the treatment of Parkinson's disease

One of the most common neurodegenerative illnesses is Parkinson's disease (PD). Rotigotine (RTG) is a dopamine agonist that exerts anti-Parkinsonian effects through dopamine receptor agonism to improve motor symptoms and overall performance in PD patients. In this study, an in situ liquid crystal gel called rotigotine-gel (RTG-gel) was developed using soya phosphatidyl choline (SPC) and glycerol dioleate (GDO) to provide long-acting slow-release benefits of rotigotine while minimizing side effects. This study prepared the RTG-gel precursor solution using SPC, GDO, and ethanol (in the ratio of 54:36:10, w/w/w). The internal structures of the gel were confirmed by crossed-polarized light microscopy (PLM), small-angle X-ray scattering (SAXS), and differential scanning calorimetry (DSC). The rheological properties of the RTG-gel precursor solution indicate a favorable combination of low viscosity and excellent flowability. The gel that produced during water absorption was also highly viscous and structurally stable, which helped to maintain the drug delayed release at the injection site. In vitro release assays showed that the in vitro release of RTG-gel followed Ritger-Peppas. The RTG-gel precursor solution was administered by subcutaneous injection, and the results of in vivo pharmacokinetic tests in SD rats showed that the plasma elimination half-life (t1/2) was 59.28 ± 16.08 h; the time to peak blood concentration (Tmax) was 12.00 ± 10.32 h, and the peak concentration (Cmax) was 29.9 ± 10.10 ng/mL. The blood concentration remained above 0.1 ng/mL for 20 days after administration and was still detectable after 31 days of administration, and the bioavailability of RTG can reach 72.59%. The results of in vitro solvent exchange tests showed that the RTG-gel precursor solution undergoes rapid exchange upon contact with PBS, and the diffusion of ethanol can reach 48.1% within 60 min and 80% within 8 h. The results of cytotoxicity test showed 89.27 ± 4.32% cell survival after administration of the drug using RTG-gel. The results of tissue extraction at the administration site showed that healing of the injection site without redness and hemorrhage could be observed after 14 days of injection. The results of tissue section of the administered site showed that the inflammatory cells decreased and granulation tissue appeared after 14 days of administration, and there was basically no inflammatory cell infiltration after 35 days of administration, and the inflammatory reaction was basically eliminated. It shows that RTG-gel has some irritation to the injection site, but it can be recovered by itself in the later stage, and it has good biocompatibility. In summary, RTG-gel might be a potential RTG extended-release formulation for treating PD.

Olfactory dysfunction and its related molecular mechanisms in Parkinson's disease

Changes in olfactory function are considered to be early biomarkers of Parkinson's disease. Olfactory dysfunction is one of the earliest non-motor features of Parkinson's disease, appearing in about 90% of patients with early-stage Parkinson's disease, and can often predate the diagnosis by years. Therefore, olfactory dysfunction should be considered a reliable marker of the disease. However, the mechanisms responsible for olfactory dysfunction are currently unknown. In this article, we clearly explain the pathology and medical definition of olfactory function as a biomarker for early-stage Parkinson's disease. On the basis of the findings of clinical olfactory function tests and animal model experiments as well as neurotransmitter expression levels, we further characterize the relationship between olfactory dysfunction and neurodegenerative diseases as well as the molecular mechanisms underlying olfactory dysfunction in the pathology of early-stage Parkinson's disease. The findings highlighted in this review suggest that olfactory dysfunction is an important biomarker for preclinical-stage Parkinson's disease. Therefore, therapeutic drugs targeting non-motor symptoms such as olfactory dysfunction in the early stage of Parkinson's disease may prevent or delay dopaminergic neurodegeneration and reduce motor symptoms, highlighting the potential of identifying effective targets for treating Parkinson's disease by inhibiting the deterioration of olfactory dysfunction.

Correlation of olfactory function factors with cardiac sympathetic denervation in Parkinson's disease

BACKGROUND

Hyposmia is a common nonmotor symptom of Parkinson's disease (PD) and reportedly associated with dysautonomia in PD. The smell identification test for measuring olfactory function consists of multiple items to discriminate specific scents. In the present study, factor analysis of the smell identification test was performed, and the correlation of extracted factors with cardiac sympathetic denervation (CSD) in patients with PD was investigated.

METHODS

The present study included 183 early PD patients who underwent the Cross-Cultural Smell Identification Test (CC-SIT) and 123I-meta-iodobenzylguanidine (123I-MIBG) myocardial scintigraphy. Factor analysis of 12 items on the CC-SIT was performed using the computed correlation matrix for the binary items, and five smell factors were extracted. Multiple linear regression was performed to determine the correlation of olfactory function with late heart-to-mediastinum (H/M) ratio of 123I-MIBG uptake.

RESULTS

The mean CC-SIT score was 6.1 ± 2.6, and 133 patients (72.7%) had CSD. The CC-SIT score and five smell factors were not associated with dopamine transporter uptake or cognitive functions. However, the CC-SIT score significantly correlated with age (P < 0.001) and late H/M ratio (P < 0.001). Factors 1 and 5 showed an increasing trend with larger H/M ratio, although it was not statistically significant (β = 0.203, P = 0.085 and β = 0.230, P = 0.085, respectively). Factor 5 significantly correlated with the H/M ratio in PD patients with CSD (β = 0.676, P = 0.036).

DISCUSSION

The results showed olfactory dysfunction to be selectively associated with cardiac sympathetic burden in PD. The correlation of certain factors with CSD indicates the possibility of selective hyposmia in PD patients.

Animal Approaches to Studying Risk Factors for Parkinson's Disease: A Narrative Review

Despite recent efforts to search for biomarkers for the pre-symptomatic diagnosis of Parkinson's disease (PD), the presence of risk factors, prodromal signs, and family history still support the classification of individuals at risk for this disease. Human epidemiological studies are useful in this search but fail to provide causality. The study of well-known risk factors for PD in animal models can help elucidate mechanisms related to the disease's etiology and contribute to future prevention or treatment approaches. This narrative review aims to discuss animal studies that investigated four of the main risk factors and/or prodromal signs related to PD: advanced age, male sex, sleep alterations, and depression. Different databases were used to search the studies, which were included based on their relevance to the topic. Although still in a reduced number, such studies are of great relevance in the search for evidence that leads to a possible early diagnosis and improvements in methods of prevention and treatment.

Advancements in Genetic and Biochemical Insights: Unraveling the Etiopathogenesis of Neurodegeneration in Parkinson's Disease

Parkinson's disease (PD) is the second most prevalent neurodegenerative movement disorder worldwide, which is primarily characterized by motor impairments. Even though multiple hypotheses have been proposed over the decades that explain the pathogenesis of PD, presently, there are no cures or promising preventive therapies for PD. This could be attributed to the intricate pathophysiology of PD and the poorly understood molecular mechanism. To address these challenges comprehensively, a thorough disease model is imperative for a nuanced understanding of PD's underlying pathogenic mechanisms. This review offers a detailed analysis of the current state of knowledge regarding the molecular mechanisms underlying the pathogenesis of PD, with a particular emphasis on the roles played by gene-based factors in the disease's development and progression. This study includes an extensive discussion of the proteins and mutations of primary genes that are linked to PD, including α-synuclein, GBA1, LRRK2, VPS35, PINK1, DJ-1, and Parkin. Further, this review explores plausible mechanisms for DAergic neural loss, non-motor and non-dopaminergic pathologies, and the risk factors associated with PD. The present study will encourage the related research fields to understand better and analyze the current status of the biochemical mechanisms of PD, which might contribute to the design and development of efficacious and safe treatment strategies for PD in future endeavors.

Behind the Mask: Parkinson's Disease and Depression

Parkinson's disease (PD) is a common, prevalent neurodegenerative disease. It is mainly characterized by motor symptoms such as rigidity, tremors, and bradykinesia, but it can also manifest with non-motor symptoms, of which depression is the most frequent. The latter can impair the quality of life, yet it gets overlooked and goes untreated because of the significant overlap in their clinical features, hence making the diagnosis difficult. Furthermore, there is limited data on the availability of appropriate criteria for making the diagnosis of depression in PD patients, as it can occur with varying expressions throughout the course of PD or it can also precede it. This review article has included a brief discussion on the diagnosis of depression in PD patients and their overlapped clinical manifestations. Understanding the mechanisms underlying the disease processes of PD and depression and the pathways interconnecting them gives better knowledge on devising treatment options for the patients. Only studies from Pubmed were included and all other databases were excluded. Studies from the last 50 years were included. Suitable references included in these studies were also extracted. Thus, depression in PD and PD in depression, along with their pharmacological and non-pharmacological treatment options, have been discussed.

Non-Motor Symptom Management: Insights into Adherence to Treatment Guidelines in Parkinson's Disease Patients

Background

Non-motor symptoms (NMS) reduce quality of life in Parkinson's disease (PD) patients, who experience three times more NMS than individuals without PD. While there are international and national NMS treatment guidelines, their implication in clinical practice remains unclear.

Objective

This study aimed to investigate the adherence to pharmacological NMS treatment guidelines in patients with mild to moderately severe PD.

Methods

220 PD patients with ≥1 NMS based on the Non-Motor Symptom Questionnaire and a Hoehn and Yahr stage ≤4 were randomly selected from the Swedish Parkinson registry and screened for inclusion. NMS were evaluated using the International Parkinson and Movement Disorder Society-Non-Motor Rating Scale (MDS-NMS), Parkinson's Disease Sleep Scale 2, Epworth Sleepiness Scale, and Hospital Anxiety and Depression Scale. Treatment was compared with Swedish national guidelines and international guidelines from the MDS Evidence-Based Medicine Committee.

Results

Among 165 included patients, the median number of NMS was 14, and in median 7 symptoms were estimated to require treatment. The most common NMS requiring treatment were pain (69%) and urinary problems (56%). Treatment of depression and constipation demonstrated the highest adherence to guidelines (79% and 77%), while dysphagia and excessive daytime sleepiness exhibited the lowest adherence (0% and 4%). On average, only 32% of NMS were treated in accordance with guidelines.

Conclusions

Adherence to pharmacological guidelines for NMS in patients with mild to severe PD was low. This study highlights the need for improved evaluation and treatment of NMS to enhance symptom management and quality of life among PD patients.

Neurotrophic phenolic glycosides from the roots of Armoracia rusticana

Armoracia rusticana P. G. Gaertner. belongs to the Brassicaceae family and has aroused scientific interest for its anti-inflammatory and anticancer activities. In a continuing investigation to discover bioactive constituents from A. rusticana, we isolated 19 phenolic glycosides including three undescribed flavonol glycosides and one undescribed neolignan glycoside from MeOH extract of this plant. Their structures were elucidated based on NMR spectroscopic analysis (1H, 13C, 1H-1H COSY, HSQC, and HMBC), HRESIMS, and chemical methods. The determination of their absolute configuration was accomplished by ECD and LC-MS analysis. All the compounds were assessed for their potential neurotrophic activity through induction of nerve growth factor in C6 glioma cell lines and for their anti-neuroinflammatory activity based on the measurement of inhibition levels of nitric oxide production and pro-inflammatory cytokines (i.e., IL-1β, IL-6, and TNF-α) in lipopolysaccharide-activated microglia BV-2 cells.

Prevalence and Influencing Factors of Depression in Patients with Parkinson's Disease

Objective

The aim was to explore the prevalence and influencing factors of depression in patients with Parkinson's disease (PD).

Methods

This was a cross-sectional study of the clinical data of 179 PD patients for retrospective analysis. Using the self-rating depression scale (SDS) and the Hamilton depression scale-21 (HAMD-21), we evaluated the prevalence of depression and analyzed the factors influencing depression in PD.

Results

The prevalence of depression in PD patients was 45.25%, and the degree of depression was mainly mild to moderate. Sleep status, daily use of levodopa, a high Hoehn and Yahr stage, a high unified Parkinson's disease rating scale (UPDRS) II score, and a high UPDRS III score were all risk factors for depression in PD patients.

Conclusion

The prevalence of depression in PD patients is high, and the degree of depression is closely related to many factors, which should receive close attention in clinical work.

Early-Life Exposure to Paraquat Aggravates Sex-Specific and Progressive Abnormal Non-Motor Neurobehavior in Aged Mice

Early-life exposure to environmental neurotoxicants is known to have lasting effects on organisms. In this study, we aim to investigate the impacts of PQ exposure during early developmental stages and adult re-challenge in aged mice on non-motor neurobehavior. Two mouse models, which were exposed once during early life stage and re-exposure at adulthood, were created to explore the long-term effects of PQ on non-motor neurobehavior. As the results showed, early-life exposure to PQ caused impairment in working memory and cognitive ability in aged male mice, but not in female mice, exhibiting a sex-specific impairment. Moreover, male mice that were re-challenged with PQ at adulthood following early-life exposure also exhibited non-motor neurobehavioral disorders. Notably, re-exposure to PQ exacerbated neurobehavioral disorders and anxiety levels compared to single exposure during different life stages. Collectively, early-life exposure to PQ can result in irreversible impairments in non-motor neurobehavior and increase susceptibility to subsequent insults in male mice, but not in female mice, suggesting greater sensitivity in male rodents to PQ-induced non-motor neurobehavioral deficits.

Patient Insights into the Diagnosis of Smell and Taste Disorders in the United States

OBJECTIVES

Diagnosis of smell/taste dysfunction is necessary for appropriate medical care. This study examines factors affecting testing and diagnosis of smell/taste disorders .

METHODS

The online USA Smell and Taste Patient Survey was made available to US patients with smell/taste disorders between April 6-20, 2022. 4,728 respondents were included.

RESULTS

1,791 (38%) patients reported a documented diagnosis. Patients most often saw family practitioners (34%), otolaryngologists (20%), and Taste/Smell clinics (6%) for smell/taste dysfunction. 64% of patients who went to Taste/Smell clinics received smell testing, followed by 39% of patients who saw otolaryngologists, and 31% of patients who saw family practitioners. Factors associated with increased odds of diagnosis included age (25-39 years (OR 2.97, 95% CI [2.25, 3.95]), 40-60 (OR 3.3, 95% CI [2.56, 4.52]), and >60 (OR 4.25, 95% CI [3.21, 5.67]) vs. 18-24 years), male gender (OR 1.26, 95% CI [1.07, 1.48]), insurance status (private (OR 1.61, 95% CI [1.15, 2.30]) or public (OR 2.03, 95% CI [1.42, 2.95]) vs. uninsured), perception of their family practitioner to be knowledgeable (OR 2.12, 95% CI [1.16, 3.90]), otolaryngologic evaluation (OR 6.17, 95% CI [5.16, 7.38]), and psychophysical smell testing (OR 1.77, 95% CI [1.42, 2.22]).

CONCLUSION

Psychophysical testing, otolaryngologic evaluation, patient assessment of family practitioner knowledge level, insurance, age, and gender are significant factors in obtaining smell/taste dysfunction diagnosis. This study identifies barriers to diagnosis including lack of insurance or access to specialist evaluation and highlights the importance of educating family practitioners in diagnosis and management of patients with smell/taste disorders.

Impact of Infusion Therapies on Quality of Life in Advanced Parkinson's Disease

A high burden of motor and non-motor parkinsonian symptoms is known to have a significant negative impact on the quality of life (QoL) of people with Parkinson's disease (PD). Effective control of these symptoms with therapies that enable patients to maintain a good QoL is therefore a key treatment goal in PD management. When symptom control can no longer be accomplished with oral or transdermal PD treatment regimens, device-aided therapies (DAT), namely levodopa and apomorphine infusion therapies, and deep brain stimulation, are valuable options to consider. DAT options may also help reduce pill burden and thereby improve compliance with treatment. Since PD therapy relies on symptomatic management, the efficacy and tolerability of any intervention is undoubtedly important, however the impact of different therapies on patient-related outcome measures, in particular health-related QoL, is also a critical consideration for those living with a chronic and disabling condition. This review discusses clinical evidence and ongoing research regarding the QoL benefits of levodopa and apomorphine infusion therapies from studies that have used validated QoL outcome measures. The data suggest that timing of these interventions is important to achieve optimal treatment effects, and that early initiation onto infusion therapies at the point when motor fluctuations emerge, and before patient QoL and functioning have significantly declined, may provide the best long-term outcomes. Healthcare professionals caring for people with PD should therefore discuss all available DAT options with them at an early stage in the course of their disease so they can make informed and timely choices that best suit them, their families and care network.

Mood disturbances in Parkinson's disease: From prodromal origins to application of animal models

Parkinson's disease (PD) is a complex illness with a constellation of environmental insults and genetic vulnerabilities being implicated. Strikingly, many studies only focus on the cardinal motor symptoms of the disease and fail to appreciate the major non-motor features which typically occur early in the disease process and are debilitating. Common comorbid psychiatric features, notably clinical depression, as well as anxiety and sleep disorders are thought to emerge before the onset of prominent motor deficits. In this review, we will delve into the prodromal stage of PD and how early neuropsychiatric pathology might unfold, followed by later motor disturbances. It is also of interest to discuss how animal models of PD capture the complexity of the illness, including depressive-like characteristics along with motor impairment. It remains to be determined how the underlying PD disease processes contributes to such comorbidity. But some of the environmental toxicants and microbial pathogens implicated in PD might instigate pro-inflammatory effects favoring α-synuclein accumulation and damage to brainstem neurons fueling the evolution of mood disturbances. We posit that comprehensive animal-based research approaches are needed to capture the complexity and time-dependent nature of the primary and co-morbid symptoms. This will allow for the possibility of early intervention with more novel and targeted treatments that fit with not only individual patient variability, but also with changes that occur over time with the evolution of the disease.

Ursolic acid enhances autophagic clearance and ameliorates motor and non-motor symptoms in Parkinson's disease mice model

Protein aggregation and the abnormal accumulation of aggregates are considered as common mechanisms of neurodegeneration such as Parkinson's disease (PD). Ursolic acid (UA), a natural pentacyclic triterpenoid compound, has shown a protective activity in several experimental models of brain dysfunction through inhibiting oxidative stress and inflammatory responses and suppressing apoptotic signaling in the brain. In this study, we investigated whether UA promoted autophagic clearance of protein aggregates and attenuated the pathology and characteristic symptoms in PD mouse model. Mice were injected with rotenone (1 mg · kg-1 · d-1, i.p.) five times per week for 1 or 2 weeks. We showed that rotenone injection induced significant motor deficit and prodromal non-motor symptoms accompanied by a significant dopaminergic neuronal loss and the deposition of aggregated proteins such as p62 and ubiquitin in the substantia nigra and striatum. Co-injection of UA (10 mg · kg-1 · d-1, i.p.) ameliorated all the rotenone-induced pathological alterations. In differentiated human neuroblastoma SH-SY5Y cells, two-step treatment with a proteasome inhibitor MG132 (0.25, 2.5 μM) induced marked accumulation of ubiquitin and p62 with clear and larger aggresome formation, while UA (5 μM) significantly attenuated the MG132-induced protein accumulation. Furthermore, we demonstrated that UA (5 μM) significantly increased autophagic clearance by promoting autophagic flux in primary neuronal cells and SH-SY5Y cells; UA affected autophagy regulation by increasing the phosphorylation of JNK, which triggered the dissociation of Bcl-2 from Beclin 1. These results suggest that UA could be a promising therapeutic candidate for reducing PD progression from the prodromal stage by regulating abnormal protein accumulation in the brain.

Neurobiology of depression in Parkinson's disease: Insights into epidemiology, molecular mechanisms and treatment strategies

Parkinson's disease (PD) is characterized mainly by motor dysfunctions due to the progressive loss of dopaminergic neurons. However, PD patients experience a multitude of debilitating non-motor symptoms, including depression, which may have deleteriously detrimental effects on life. Depression is multifactorial and exhibits a bimodal progression in PD, but its underlying molecular mechanisms are poorly understood. Studies demonstrating the pathophysiology of depression in PD and the specific treatment strategies for depression-like symptoms in PD patients are largely lacking, often underrated, under-recognized and, consequently, inadequately/under-treated. Nevertheless, reports suggest that the incidence of depression is approximately 20-30% of PD patients and may precede the onset of motor symptoms. Diagnosing depression in PD becomes difficult due to the clinical overlap in symptomatology between the two diseases, and the nigrostriatal dysfunction alone is insufficient to explain depressive symptoms in PD. Therefore, the current study provides an overview of the molecular mechanisms underlying the development of depression in PD and new insights into developing current antidepressant strategies to treat depression in PD. This review will identify and understand the molecular pathological mechanisms of depression in PD that will fundamentally help tailoring therapeutic interventions for depressive symptoms in PD.

Nicotine-Mediated Rescue of α-Synuclein Toxicity Requires Synaptic Vesicle Glycoprotein 2 in Drosophila

BACKGROUND

Parkinson's disease (PD) is characterized by α-synuclein aggregation and loss of dopamine neurons. Risk of PD arises due to a combination of genetic and environmental factors, which may interact, termed gene-environment (G×E) interactions. An inverse association between smoking and the risk of PD is well established, and a previous genome-wide G×E interaction study identified genetic variation in the synaptic-vesicle glycoprotein 2C (SV2C) locus as an important mediator of the degree to which smoking is inversely associated with PD.

OBJECTIVE

We sought to determine the mechanism of the smoking-SV2C interaction in a Drosophila model of PD.

METHODS

Flies expressing human α-synuclein in all neurons develop the hallmarks of PD, including motor dysfunction, loss of dopaminergic (DA) neurons, and formation of α-synuclein inclusions. We assessed the effects of increasing doses of nicotine on these parameters of neurodegeneration, in the presence or absence of knockdown of two Drosophila orthologues of SV2, hereafter referred to as SV2L1 and SV2L2.

RESULTS

The α-synuclein-expressing flies treated with nicotine had improved locomotion, DA neuron counts, and α-synuclein aggregation. However, in α-synuclein-expressing flies in which SV2L1 and SV2L2 were knocked down, nicotine failed to rescue neurodegeneration.

CONCLUSIONS

This work confirms a G×E interaction between nicotine and SV2, defines a role for this interaction in α-synuclein proteostasis, and suggests that future clinical trials on nicotine should consider genetic variation in SV2C. Furthermore, this provides proof of concept that our model can be used for the mechanistic study of G×E, paving the way for the investigation of additional G×E interactions or the identification of novel G×E. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Differentiated HT22 cells as a novel model for in vitro screening of serotonin reuptake inhibitors

The mouse hippocampal neuronal cell line HT22 is frequently used as an in vitro model to investigate the role of hippocampal cholinergic neurons in cognitive functions. HT22 cells are derived from hippocampal neuronal HT4 cells. However, whether these cells exhibit the serotonergic neuronal phenotype observed in mature hippocampal neurons has not been determined yet. In this present study, we examined whether the differentiation of HT22 cells enhances the serotonergic neuronal phenotype, and if so, whether it can be used for antidepressant screening. Our results show that differentiation of HT22 cells promoted neurite outgrowth and upregulation of N-methyl-D-aspartate receptor and choline acetyltransferase, which is similar to that observed in primary cultured hippocampal neurons. Furthermore, proteins required for serotonergic neurotransmission, such as tryptophan hydroxylase 2, serotonin (5-hydroxytryptamine, 5-HT)_1a receptor, and serotonin transporter (SERT), were significantly upregulated in differentiated HT22 cells. The transcription factor Pet-1 was upregulated during HT22 differentiation and was responsible for the regulation of the serotonergic neuronal phenotype. Differentiation also enhanced the functional serotonergic properties of HT22 cells, as evidenced by increase in intracellular 5-HT levels, serotonin transporter SERT glycosylation, and 5-HT reuptake activity. The sensitivity of 5-HT reuptake inhibition by venlafaxine in differentiated HT22 cells (IC_50, 27.21 nM) was comparable to that in HEK293 cells overexpressing serotonin transporter SERT (IC_50, 30.65 nM). These findings suggest that the differentiation of HT22 cells enhances their functional serotonergic properties, and these cells could be a potential in vitro system for assessing the efficacy of antidepressant 5-HT reuptake inhibitors.

Changes in the Neuronal Architecture of the Hippocampus in a 6-Hydroxydopamine-Lesioned Rat Model of Parkinson Disease

PURPOSE

Parkinson disease (PD) is a progressive neurodegenerative disorder in which dopaminergic (DAergic) systems are destroyed (particularly in the nigrostriatal system), causing both motor and nonmotor symptoms. Hippocampal neuroplasticity is altered in PD animal models, resulting in nonmotor dysfunctions. However, little is known about the precise mechanism underlying the hippocampal dysfunctions in PD.

METHODS

Striatal 6-hydroxydopamine (6-OHDA) infusions were performed unilaterally in adult Sprague Dawley rats. Both motor and nonmotor symptoms alongside the expression of tyrosine hydroxylase (TH) in the substantia nigra and striatum were confirmed in 6-OHDA-lesioned rats. The neuronal architecture in the hippocampus was analyzed by Golgi staining.

RESULTS

During the 7-8 weeks after infusion, the 6-OHDA-lesioned rats exhibited motor and nonmotor dysfunctions (especially anxiety/depression-like behaviors). Rats with unilateral 6-OHDA infusion displayed reduced TH+ immunoreactivity in the ipsilateral nigrostriatal pathway of the brain. Golgi staining revealed that striatal 6-OHDA infusion significantly decreased the dendritic complexity (i.e., number of crossing dendrites, total dendritic length, and branch points) in the ipsilateral hippocampal conus ammonis 1 (CA1) apical/basal and dentate gyrus (DG) subregions. Additionally, the dendritic spine density and morphology were significantly altered in the CA1 apical/basal and DG subregions following striatal 6-OHDA infusion. However, alteration of microglial and astrocytic distributions did not occur in the hippocampus following striatal 6-OHDA infusion.

CONCLUSION

The present study provides anatomical evidence that the structural plasticity in the hippocampus is altered in the late phase following striatal 6-OHDA infusion in rats, possibly as a result of the prolonged suppression of the DAergic system, and independent of neuroinflammation.

Bioinformatics Analysis of Inflammation Gene Signature in Indicating Cholangiocarcinoma Prognosis

Aim. We studied inflammatory response-related genes in cholangiocarcinoma by bioinformatics analysis. Methods. The expression profiles and clinical information of cholangiocarcinoma patients were downloaded from the TCGA cohort and the Gene Expression Omnibus. The greatest absolute shrinking and selecting operator Cox analyses were utilized to build a multigene predictive signature. Results. An inflammation response-related gene profile was generated using LASSO-Cox regression analysis of Homo sapiens bestrophin 1 (BEST1), Chemokine (C–C motif) ligand 2 (CCL2), and plasminogen activator, urokinase receptor (PLAUR). Individuals in the highest category had a significantly lower overall survival time than those from the low-risk group. A receiver operating curve analysis was used to demonstrate the predictive ability of the predictive gene signature. Through multivariate Cox analysis, the risk score was discovered to be a predictor of overall survival (OS). According to functional assessments, the immunological state and milieu of the two risk areas were significantly different. The expression levels of predictive genes were found to be strongly linked to the sensitivity of cancer cells to antitumor therapy. Conclusion. A new signature made up of three respective response-relevant genes is found to be a promising indicator of prognosis by influencing the immune condition and tumor microenvironment.

Zishen pingchan granules combined with pramipexole in the improvement of depressive symptoms in Parkinson's disease: a prospective, multicenter, randomized, double-blind, controlled clinical study

Background and objective

Zishen Pingchan granule (ZPG), a traditional Chinese herbal recipe for treating Parkinson’s disease (PD), is usually used as an add-on drug with some antiparkinsonian drugs in China. The objectives of this study were to evaluate the efficacy, safety, and tolerability of ZPG combined with pramipexole in the treatment of depression in PD (dPD).

Methods

A 12-week, multicenter, randomized, double-blind, and placebo-controlled study on ZPG was performed on a total of 200 patients who were treated with pramipexole but still had mild to moderate depressive symptoms. Patients were randomly divided into ZPG (n = 100) or placebo (n = 100). The primary effective result was the mean change from the baseline on the Hamilton Depression Scale 17 items (HAM-D-17) over 12 weeks and the clinical efficacy rate. Secondary endpoints were the mean change from the baseline in the Geriatric Depression Scale (GDS-15), Unified Parkinson's disease rating scale Part III (UPDRS III), Parkinson's quality of life scale (PDQ-8), and Parkinson's disease sleep scale (PDSS-2) over 12 weeks.

Results

After 12 weeks of treatment, ZPG significantly reduced the mean [95% confidence interval] HAMD score vs. placebo (− 1.43 scores [− 2.50, − 0.36]; p = 0.009). The clinical remission rate and responders of the ZPG group were higher than those of the placebo (46.1% vs. 31.0%; p = 0.041; 34.8% vs. 18.4%; p = 0.014). A significant improvement in the PDSS-2 score was also observed in the ZPG group compared with that in the placebo group (− 3.56 scores [− 5.77, − 1.35]; p = 0.002). A total of 7 patients (7.1%) in the ZPG group had mild adverse events (AEs) vs 9 patients (9%) in the placebo group. No severe AEs were observed in either group. The randomization and controlled clinical study revealed that ZPG was effective, safe, and well-tolerated.

Conclusion

ZPG combined with pramipexole further reduced the depressive symptoms and improved the sleeping quality of PD patients.

Trial registration The protocol was retrospectively registered at the Chinese Clinical Trial Registry, Unique identifier: ChiCTR1800019942, date of registration: December 9, 2018; http://www.chictr.org.cn/showproj.aspx?proj=30432

ERRγ Ligand Regulates Adult Neurogenesis and Depression-like Behavior in a LRRK2-G2019S-associated Young Female Mouse Model of Parkinson's Disease

Adult neurogenesis, a process controlling the proliferation to maturation of newly generated neurons in the post-developmental brain, is associated with various brain functions and pathogenesis of neuropsychological diseases, such as Parkinson's disease (PD) and depression. Because orphan nuclear receptor estrogen-related receptor γ (ERRγ) plays a role in the differentiation of neuronal cells, we investigated whether an ERRγ ligand enhances adult neurogenesis and regulates depressive behavior in a LRRK2-G2019S-associated mouse model of PD. Young female LRRK2-G2019S mice (7-9 weeks old) showed depression-like behavior without dopaminergic neuronal loss in the nigrostriatal pathway nor motor dysfunction. A significant decrease in adult hippocampal neurogenesis was detected in young female LRRK2-G2019S mice, but not in comparable male mice. A synthetic ERRγ ligand, (E)-4-hydroxy-N'-(4-(phenylethynyl)benzylidene)benzohydrazide (HPB2), ameliorated depression-like behavior in young female LRRK2-G2019S mice and enhanced neurogenesis in the hippocampus, as evidenced by increases in the number of bromodeoxyuridine/neuronal nuclei-positive cells and in the intensity and number of doublecortin-positive cells in the hippocampal dentate gyrus (DG). Moreover, HPB2 significantly increased the number of spines and the number and length of dendrites in the DG of young female LRRK2-G2019S mice. Furthermore, HPB2 upregulated brain-derived neurotrophic factor (BDNF)/tropomyosin receptor kinase B (TrkB) signaling, one of the important factors regulating neurogenesis, as well as phosphorylated cAMP-response element binding protein-positive cells in the DG of young female LRRK2-G2019S mice. Together, these results suggest ERRγ as a novel therapeutic target for PD-associated depression by modulating adult neurogenesis and BDNF/TrkB signaling.

Associations of Sleep Disorders With Depressive Symptoms in Early and Prodromal Parkinson's Disease

Background

Non-motor symptoms, including sleep disorders and depression, are common in Parkinson’s disease (PD). The purpose of our study is to explore the effect of sleep disorders, including the probable rapid eye movement (REM) sleep behavior disorder (pRBD) and the daytime sleepiness, on depressive symptoms in patients with early and prodromal PD.

Methods

A total of 683 participants who obtained from the Parkinson Progression Markers Initiative (PPMI) were included, consisting of 423 individuals with early PD, 64 individuals with prodromal PD, and 196 healthy controls (HCs), who were followed up to 5 years from baseline. Multiple linear regression models and linear mixed-effects models were conducted to explore the relationship between sleep disorders and depression at baseline and longitudinally, respectively. Multiple linear regression models were used to further investigate the association between the change rates of daytime sleepiness score and depression-related score. Mediation analyses were also performed.

Results

At baseline analysis, individuals with early and prodromal PD, who had higher RBD screening questionnaire (RBDSQ) score, or who were considered as pRBD, or who manifested specific behaviors of RBD (things falling down when sleep or disturbance of sleep), showed significantly the higher score of depression-related questionnaires. Our 5-year follow-up study showed that sleep disorders, including pRBD and daytime sleepiness, were associated with the increased depressive-related score in individuals with early and prodromal PD. Interestingly, we also found that the increased possibilities of daytime sleepiness were associated with depressive-related score. Finally, mediation analysis demonstrated that the relationship between RBD and depressive symptoms was partially mediated by autonomic symptoms, such as postural hypertension, salivation, dysphagia, and constipation.

Conclusion

Our study shows that sleep disorders, including pRBD and daytime sleepiness, are associated with depression at baseline and longitudinally, which is partially mediated by the autonomic dysfunction in early and prodromal PD, with an implication that sleep management is of great value for disease surveillance.

Trehalose ameliorates prodromal non-motor deficits and aberrant protein accumulation in a rotenone-induced mouse model of Parkinson's disease

Trehalose has been recently revealed as an attractive candidate to prevent and modify Parkinson's disease (PD) progression by regulating autophagy; however, studies have only focused on the reduction of motor symptoms rather than the modulation of disease course from prodromal stage. This study aimed to evaluate whether trehalose has a disease-modifying effect at the prodromal stage before the onset of a motor deficit in 8-week-old male C57BL/6 mice exposed to rotenone. We found significant decrease in tyrosine hydroxylase immunoreactivity in the substantia nigra and motor dysfunction after 2 weeks rotenone treatment. Mice exposed to rotenone for a week showed an accumulation of protein aggregates in the brain and prodromal non-motor deficits, such as depression and olfactory dysfunction, prior to motor deficits. Trehalose significantly improved olfactory dysfunction and depressive-like behaviors and markedly reduced α-synuclein and p62 deposition in the brain. Trehalose further ameliorated motor impairment and loss of nigral tyrosine hydroxylase-positive cells in rotenone-treated mice. We demonstrated that prodromal non-motor signs in a rotenone-induced PD mouse model are associated with protein aggregate accumulation in the brain and that an autophagy inducer could be valuable to prevent PD progression from prodromal stage by regulating abnormal protein accumulation.