ATF5 Attenuates the Secretion of Pro-Inflammatory Cytokines in Activated Microglia.

The highly dynamic changes in microglia necessary to achieve a rapid neuroinflammatory response require a supply of energy from mitochondrial respiration, which leads to the accumulation of unfolded mitochondrial proteins. We previously reported that microglial activation is correlated with the mitochondrial unfolded protein response (UPRmt) in a kaolin-induced hydrocephalus model, but we still do not know the extent to which these changes in microglia are involved in cytokine release. Here, we investigated the activation of BV-2 cells and found that treatment with lipopolysaccharide (LPS) for 48 h increased the secretion of pro-inflammatory cytokines. This increase was accompanied by a concurrent decrease in oxygen consumption rate (OCR) and mitochondrial membrane potential (MMP), in association with the up-regulation of the UPRmt. Inhibition of the UPRmt by knockdown of ATF5, a key upstream regulator of the UPRmt, using small-interfering RNA against ATF5 (siATF5) not only increased production of the pro-inflammatory cytokines, interleukin-6 (IL-6), IL-1ß and tumor necrosis factor-α (TNF-α), but also decreased MMP. Our results suggest that ATF5-dependent induction of the UPRmt in microglia acts as a protective mechanism during neuroinflammation and may be a potential therapeutic target for reducing neuroinflammation.

Melatonin attenuates MPP+-induced apoptosis via heat shock protein in a Parkinson's disease model.

Heat shock proteins (HSPs) play an essential role as molecular chaperones to prevent abnormal protein aggregation and misfolding. Moreover, they protect dopamine neurons from oxidative stress, inflammation, and apoptosis, all well-known pathomechanisms of Parkinson's disease (PD). Melatonin is a potent antioxidant that has the beneficial ability to prevent neurodegenerative diseases like PD. We aimed to explore the protective properties of melatonin in an in vitro PD model, focusing on its underlying mechanism using HSPs. A 1-methyl-4-phenylpyridimium (MPP+)-induced toxin model was established with retinoic acid (RA)-differentiated SH-SY5Y cells. Cell viability and apoptosis were measured using MTT and DAPI. Intracellular reactive oxygen species (ROS) levels were measured by the cell-permeant fluorescent probe DCFH-DA. The level of malondialdehyde and the activities of superoxide dismutase and glutathione peroxidase were assessed using ELISA kits. Apoptotic markers of Bax, Bcl2, and cleaved caspase-3, as well as HSP70 and heat shock factor-1 (HSF1), were measured by Western blot. The melatonin effect through HSP70 was tested with silencing of HSF1 in the MPP + -treated SH-SY5Y cells. Melatonin can protect against MPP + -induced neuronal toxicity by promoting anti-oxidative and anti-apoptotic properties. SH-SY5Y cells exposed to melatonin with MPP + showed increased expression of HSP70 and HSF1 compared with those exposed to MPP + alone. However, siRNA-mediated downregulation of HSF1 significantly attenuated the protective effects of melatonin in the MPP + -induced in vitro PD model. Our findings revealed the protective roles of melatonin in an in vitro PD model. Melatonin can hinder the toxic effects of MPP + on dopaminergic neuronal cells via upregulation of the HSF1/HSP70 pathway. Further experimental studies would verify the therapeutic relevance of melatonin with HSP70 and HSF1 to prevent and decelerate PD-like neurodegeneration.

A new swallowing supplement for dysphagia in patients with Parkinson's disease.

Dysphagia associated with Parkinson's disease (PD) affects the mortality and quality of life of patients with PD. Avoiding aspiration and maintaining swallowing ability are among the concerns regarding PD care. Therefore, we developed a swallowing supplement for easier swallowing and tolerability in patients with PD. Thirty patients with PD and 50 healthy controls were enrolled and their swallowing function measured using the videofluoroscopic swallowing study (VFSS) and several dysphagia scales. The Unified Parkinson's Disease Rating Scale motor scores, Hoehn and Yahr stage, and levodopa doses were evaluated in patients with PD. The VFSS and survey were used to assess the viscosity, color, taste, nutrition, safety, and tolerability of the swallowing supplement. The MMSE score, serum albumin, and hemoglobin levels, and oral conditions were worse in the PD group than in the control group. Compared with controls, patients with PD had significantly lower total and sub-item scores of the swallowing quality of life (swal-QoL). Using commercialized yogurt, the pharyngeal delay time (PDT) and the modified penetration aspiration scale were higher in the PD group than in the control group. The swallowing supplement significantly shortened the PDT and pharyngeal transit time (PTT). Moreover, compared with commercialized yogurt, it improved pharyngeal wall coating, PTT, and aspiration in the videofluoroscopic dysphagia subscales. The survey scores were above average to good in the "easy swallowing" and "pharyngeal residual sense" items and tolerable in the remaining 6 preference items. This swallowing supplement could prevent aspiration and dysphagia complications in patients with PD.

What Shall We Do for the Patients with Shaky Leg Syndrome? A Review of 23 Patients.

Orthostatic tremor (OT) is not an uncommon symptom in various neurodegenerative diseases. However, the nature and pathophysiology of OT involve a complex network of tremors and dopaminergic pathways. We assessed patients who complained of prominent leg tremors described as "shaky leg." We analyzed their characteristics and evaluated them with neuroimaging and electrophysiological tools. A total of 23 patients who experienced an uncomfortable symptom of leg tremor were retrospectively enrolled from April 2014 to October 2019. Previous medical history, brain MRI, and surface electromyography (EMG) data were analyzed. The [18F]-FP-CIT brain positron emission tomography (PET) and the Unified Parkinson's Disease Rating Scale (UPDRS) were assessed for patients who showed parkinsonism. The causes of OT varied: parkinsonism (n = 5), idiopathic causes (n = 4), secondary causes (n = 3, trauma, brain lesion, arteriovenous malformation), drug reactions (n = 3, valproate, perphenazine, haloperidol), other neurological disorders (n = 5, essential tremor, dystonia, restless leg syndrome, REM sleep behavior disorder, dementia), alcohol withdrawal (n = 1), functional movement disorder (n = 1), and an unknown cause (n = 1). The frequency range varied (2.6-15 Hz) and according to the new consensus statement on the classification of OT, 4 patients had primary OT, 2 had "primary OT plus," 12 had slow OT, and 5 had orthostatic myoclonus. The prognosis associated with the use of medication was generally poor; however, clonazepam and levodopa were the most effective drugs. In conclusion, we found that different types of OT and orthostatic myoclonus were diagnosed by electrophysiological evaluation and neuroimaging tools even if they showed the same symptoms as "shaky leg." In addition, it is possible to roughly estimate the response to medication according to the type of OT and the cause. To clarify the pathophysiology of OT, a large number of longitudinal cohort studies and detailed neuroimaging and electrophysiological evaluations are needed.

Non-cell autonomous modulation of tyrosine hydroxylase by HMGB1 released from astrocytes in an acute MPTP-induced Parkinsonian mouse model.

High-mobility group box 1 (HMGB1) is actively secreted from inflammatory cells and acts via a non-cell-autonomous mechanism to play an important role in mediating cell proliferation and migration. The HMGB1-RAGE (receptor for advanced glycation end products) axis upregulates tyrosine hydroxylase (TH) expression in response to extracellular insults in dopaminergic neurons in vitro, but little is known about HMGB1 in modulation of dopaminergic neurons in vivo. Here, using immunohistochemistry, we show that HMGB1 and RAGE expression are higher in the nigral area of MPTP (methyl-4-phenyl-1,2,3,6-tetrahydropyridine)-treated mice, a toxin-induced Parkinsonian mouse model, compared with saline-treated controls. HMGB1 was predominantly localized to astrocytes and may affect neighboring dopaminergic neurons in the MPTP mouse model, owing to co-localization of RAGE in these TH-positive cells. In addition, MPTP induced a decrease in TH expression, an effect that was potentiated by inhibition of c-Jun N-terminal kinase (JNK) or RAGE. Moreover, stereotaxic injection of recombinant HMGB1 attenuated the MPTP-induced reduction of TH in a Parkinsonian mouse model. Collectively, our results suggest that an increase of HMGB1, released from astrocytes, upregulates TH expression in an acute MPTP-induced Parkinsonian mouse model, thereby maintaining dopaminergic neuronal functions.

Association between White Matter Lesions and Non-Motor Symptoms in Parkinson Disease.

BACKGROUND: There are only few studies exploring the relationship between white matter lesions (WMLs) and non-motor symptoms in Parkinson disease (PD). This study aimed to investigate the association between WMLs and the severity of non-motor symptoms in PD. METHODS: The severity of motor dysfunction, cognitive impairment, and non-motor symptoms was assessed by various scales in 105 PD patients. We used a visual semiquantitative rating scale and divided the subjects into four groups: no, mild, moderate, and severe WMLs. We compared the means of all scores between the four groups and analyzed the association between the severity of WMLs and the specific domain of non-motor symptoms. RESULTS: The non-motor symptoms as assessed by the Non-Motor Symptoms Scale, Parkinson's Disease Questionnaire (PDQ-39), Parkinson's Disease Sleep Scale, Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), Neuropsychiatric Inventory (NPI), and Parkinson Fatigue Scale (PFS) were significantly worse in the patients with moderate and severe WMLs than in those without WMLs. Compared with the no WML group, the scores for motor dysfunction were significantly higher in the mild, moderate, and severe WML groups. The scores for cognitive dysfunction were significantly higher in the patients with severe WMLs than in those without WMLs. The severity of WMLs showed linear associations with PFS, BDI, BAI, NPI, and PDQ-39 scores. The severity of WMLs also correlated linearly with scores for motor and cognitive dysfunction. CONCLUSIONS: Among the non-motor symptoms, fatigue, depression, anxiety, and quality of life were significantly affected by WMLs in PD. Confirmation of the possible role of WMLs in non-motor symptoms associated with PD in a prospective manner may be crucial not only for understanding non-motor symptoms but also for the development of treatment strategies.

Characteristic Motor and Nonmotor Symptoms Related to Quality of Life in Drug-Naïve Patients with Late-Onset Parkinson Disease.

BACKGROUND/AIMS: Unlike young-onset Parkinson disease (YOPD), characteristics of late-onset PD (LOPD) have not yet been clearly elucidated. We investigated characteristic features and symptoms related to quality of life (QoL) in LOPD patients. METHODS: We recruited drug-naïve, early PD patients. The patient cohort was divided into 3 subgroups based on patient age at onset (AAO): the YOPD group (AAO <50 years), the middle-onset PD (MOPD) group, and the LOPD group (AAO ≥70 years). Using various scales for motor symptoms (MS) and non-MS (NMS) and QoL, we compared the clinical features and impact on QoL. RESULTS: Of the 132 enrolled patients, 26 were in the YOPD group, 74 in the MOPD group, and 32 in the LOPD group. Among parkinsonian symptoms, patients in the LOPD group had a lower score on the Korean version of the Montreal Cognitive Assessment than the other groups. Logistic regression analysis showed genitourinary symptoms were related to the LOPD group. Linear regression analysis showed both MS and NMS were correlated with QoL in the MOPD group, but only NMS were correlated with QoL in the LOPD group. Particularly, anxiety and fatigue affected QoL in the LOPD group. CONCLUSION: LOPD patients showed different characteristic clinical features, and different symptoms were related with QoL for LOPD than YOPD and MOPD patients.

Activation of the HMGB1-RAGE axis upregulates TH expression in dopaminergic neurons via JNK phosphorylation.

The derangement of tyrosine hydroxylase (TH) activity reduces dopamine synthesis and is implicated in the pathogenesis of Parkinson's disease. However, the extracellular modulator and intracellular regulatory mechanisms of TH have yet to be identified. Recently, high-mobility group box 1 (HMGB1) was reported to be actively secreted from glial cells and is regarded as a mediator of dopaminergic neuronal loss. However, the mechanism for how HMGB1 affects TH expression, particularly through the receptor for advanced glycation endproducts (RAGE), has not yet been investigated. We found that recombinant HMGB1 (rHMGB1) upregulates TH mRNA expression via simultaneous activation of JNK phosphorylation, and this induction of TH expression is blocked by inhibitors of RAGE and JNK. To investigate how TH expression levels change through the HMGB1-RAGE axis as a result of MPP+ toxicity, we co-treated SN4741 dopaminergic cells with MPP+ and rHMGB1. rHMGB1 blocked the reduction of TH mRNA following MPP+ treatment without altering cell survival rates. Our results suggest that HMGB1 upregulates TH expression to maintain dopaminergic neuronal function via activating RAGE, which is dependent on JNK phosphorylation.

Gender Differences of Nonmotor Symptoms Affecting Quality of Life in Parkinson Disease.

BACKGROUND/AIMS: Gender differences of health-related quality of life (HRQoL) in patients with various disorders have been reported. Various nonmotor symptoms (NMSs) also affect the patients' lives and HRQoL, even in the early stages of Parkinson disease (PD). Our study aimed to identify whether there are gender differences of HRQoL in PD patients in the early stages, and which NMSs are associated with HRQoL depending on gender. METHOD: Eighty-nine PD patients (47 males, 42 females) and 36 healthy controls were enrolled. We evaluated HRQoL, NMSs, and their associations in each gender. RESULT: The total Parkinson Disease Quality of Life Questionnaire and Beck Anxiety Inventory scores were higher in female patients than in male patients. The correlation analysis revealed no association between NMSs and HRQoL in male patients. In female patients, HRQoL was highly correlated with depression, and moderately associated with fatigue. CONCLUSIONS: Gender differences of an association between HRQoL and NMSs exist in PD. We found that fatigue and depression were the main determinants of poor HRQoL in female patients even in the early stages. We suggest that a gender-specific therapeutic approach is important, and it is necessary to pay special attention to the predictors associated with causing poor HRQoL.

Public Awareness and Knowledge about Parkinson's Disease: A National Population Based Survey in South Korea.

BACKGROUND: Considering the increasing prevalence of Parkinson's disease (PD), the lack of awareness and knowledge regarding PD may be barriers to the early diagnosis and the provision of optimal care to affected patients. This study aimed to investigate the awareness and knowledge about PD among the general population in South Korea and to identify the factors that are associated with these parameters. METHODS: We developed a structured, 22-item questionnaire that consisted of both open-ended and close-ended questions. A total of 1,000 people from the general public were randomly sampled in proportion to the country's population density and were questioned by well-trained interviewers. Multivariate logistic regression analysis was applied to identify the factors associated with awareness and knowledge of PD. RESULTS: Age, household income and education level were independently associated with awareness of PD. Subjects between 40 and 59 years of age and those who had completed more than 12 years of education showed more awareness of PD. Regarding knowledge about PD, younger subjects exhibited the least knowledge compared to respondents between 40 and 59 years of age and those above 60 years of age. Low socioeconomic status tended to be associated with poor knowledge of PD. CONCLUSIONS: Awareness and knowledge of PD showed hierarchical gradients with respect to age, income and education level. Pertinent educational strategies and approaches targeting specific subgroups are necessary to improve public awareness and knowledge about PD.

Dysport and Botox at a ratio of 2.5:1 units in cervical dystonia: a double-blind, randomized study.

We aimed to compare Dysport (abobotulinumtoxinA, Ipsen Biopharm, Slough, UK) and Botox (onabotulinumtoxinA, Allergan, Irvine, CA, USA) at a 2.5:1 ratio in the treatment of cervical dystonia (CD). A Dysport/Botox ratio of lower than 3:1 was suggested as a more appropriate conversion ratio, considering its higher efficacy and more frequent incidence of adverse effects not only in the treatment of CD but also in other focal movement disorders. A randomized, double-blind, multicenter, non-inferiority, two-period crossover study was done in CD, with a duration of at least 18 months. Patients were randomly assigned to treatment for the first period with Dysport or Botox, and they were followed up for 16 weeks after the injection. After a 4-week washout period, they were switched to the other formulation and then followed up for 16 weeks. The primary outcome was the changes in the Tsui scale between the baseline value and that at 1 month after each injection. A total of 103 patients were enrolled, and 94 completed the study. Mean changes in the Tsui scale between baseline and 4 weeks after each injection tended to favor Botox; however, this was not statistically significant (4.0 ± 3.9 points for the Dysport treatment vs. 4.8 ± 4.1 points for Botox; 95% confidence interval, -0.1-1.7; P = 0.091). The mean change of the Toronto western spasmodic torticollis rating scale score, the proportion of improvement in clinical global impression and patient global impression, and the incidences of adverse events were not significantly different between the two treatments. With regard to safety and efficacy, Dysport was not inferior to Botox in patients with CD at a conversion factor of 2.5:1. [clinicaltrial.gov: NCT00950664]

Neuropathogenesis-on-chips for neurodegenerative diseases.

Developing diagnostics and treatments for neurodegenerative diseases (NDs) is challenging due to multifactorial pathogenesis that progresses gradually. Advanced in vitro systems that recapitulate patient-like pathophysiology are emerging as alternatives to conventional animal-based models. In this review, we explore the interconnected pathogenic features of different types of ND, discuss the general strategy to modelling NDs using a microfluidic chip, and introduce the organoid-on-a-chip as the next advanced relevant model. Lastly, we overview how these models are being applied in academic and industrial drug development. The integration of microfluidic chips, stem cells, and biotechnological devices promises to provide valuable insights for biomedical research and developing diagnostic and therapeutic solutions for NDs.

Clinical and Genetic Characteristics Associated With Survival Outcome in Late-Onset Huntington's Disease in South Korea.

BACKGROUND AND PURPOSE: The onset of Huntington's disease (HD) usually occurs before the age of 50 years, and the median survival time from onset is 15 years. We investigated survival in patients with late-onset HD (LoHD) (age at onset ≥60 years) and the associations of the number of mutant CAG repeats and age at onset (AAO) with survival in patients with HD. METHODS: Patients with genetically confirmed HD at six referral centers in South Korea between 2000 and 2020 were analyzed retrospectively. Baseline demographic, clinical, and genetic characteristics and the survival status as at December 2020 were collected. RESULTS: Eighty-seven patients were included, comprising 26 with LoHD (AAO=68.77±5.91 years, mean±standard deviation; 40.54±1.53 mutant CAG repeats) and 61 with common-onset HD (CoHD) (AAO=44.12±8.61 years, 44.72±4.27 mutant CAG repeats). The ages at death were 77.78±7.46 and 53.72±10.86 years in patients with LoHD and CoHD, respectively (p<0.001). The estimated survival time was 15.21±2.49 years for all HD patients, and 10.74±1.95 and 16.15±2.82 years in patients with LoHD and CoHD, respectively. More mutant CAG repeats and higher AAO were associated with shorter survival (hazard ratio [HR]=1.05, 95% confidence interval [CI]=1.01-1.09, p=0.019; and HR=1.17, 95% CI=1.03-1.31, p=0.013; respectively) for all HD patients. The LoHD group showed no significant factors associated with survival after disease onset, whereas the number of mutant CAG repeats had a significant effect (HR=1.12, 95% CI=1.01-1.23, p=0.034) in the CoHD group. CONCLUSIONS: Survival after disease onset was shorter in patients with LoHD than in those with CoHD. More mutant CAG repeats and higher AAO were associated with shorter survival in patients with HD.

Establishment of a registry of clinical data and bioresources for rare nervous system diseases.

Rare diseases are predominantly genetic or inherited, and patients with these conditions frequently exhibit neurological symptoms. Diagnosing and treating many rare diseases is a complex challenge, and their low prevalence complicates the performance of research, which in turn hinders the advancement of therapeutic options. One strategy to address this issue is the creation of national or international registries for rare diseases, which can help researchers monitor and investigate their natural progression. In the Republic of Korea, we established a registry across 5 centers that focuses on 3 rare diseases, all of which are characterized by gait disturbances resulting from motor system dysfunction. The registry will collect clinical information and human bioresources from patients with amyotrophic lateral sclerosis, spinocerebellar ataxia, and hereditary spastic paraplegia. These resources will be stored at ICreaT and the National Biobank of Korea. Once the registry is complete, the data will be made publicly available for further research. Through this registry, our research team is dedicated to identifying genetic variants that are specific to Korean patients, uncovering biomarkers that show a strong correlation with clinical symptoms, and leveraging this information for early diagnosis and the development of treatments.

Caregiver Burden of Patients With Huntington's Disease in South Korea.

OBJECTIVE: This is the first prospective cohort study of Huntington's disease (HD) in Korea. This study aimed to investigate the caregiver burden in relation to the characteristics of patients and caregivers. METHODS: From August 2020 to February 2022, we enrolled patients with HD from 13 university hospitals in Korea. We used the 12-item Zarit Burden Interview (ZBI-12) to evaluate the caregiver burden. We evaluated the clinical associations of the ZBI-12 scores by linear regression analysis and investigated the differences between the low- and high-burden groups. RESULTS: Sixty-five patients with HD and 45 caregivers were enrolled in this cohort study. The average age at onset of motor symptoms was 49.3 ± 12.3 years, with an average cytosine-adenine-guanine (CAG)n of 42.9 ± 4.0 (38-65). The median ZBI-12 score among our caregivers was 17.6 ± 14.2. A higher caregiver burden was associated with a more severe Shoulson-Fahn stage (p = 0.038) of the patients. A higher ZBI-12 score was also associated with lower independence scale (B = -0.154, p = 0.006) and functional capacity (B = -1.082, p = 0.002) scores of patients. The caregiving duration was longer in the high- than in the low-burden group. Caregivers' demographics, blood relation, and marital and social status did not affect the burden significantly. CONCLUSION: HD patients' neurological status exerts an enormous impact on the caregiver burden regardless of the demographic or social status of the caregiver. This study emphasizes the need to establish an optimal support system for families dealing with HD in Korea. A future longitudinal analysis could help us understand how disease progression aggravates the caregiver burden throughout the entire disease course.

Seven-Tesla magnetic resonance images of the substantia nigra in Parkinson disease.

OBJECTIVE: To investigate anatomical changes in the substantia nigra (SN) of Parkinson disease (PD) patients with age-matched controls by using ultra-high field magnetic resonance imaging (MRI). METHODS: We performed 7T MRI in 10 PD and 10 age-matched control subjects. Magnetic resonance images of the SN were obtained from a 3-dimensional (3D) T(2)*-weighted gradient echo sequence. Region of interest-based 3D shape analysis was performed to quantitatively compare images from the 2 groups. RESULTS: The boundary between the SN and crus cerebri was not smooth in PD subjects. Undulation in the lateral surface of the SN appeared more intense in the side contralateral to that with the more severe symptoms, and more prominent at the rostral level of the SN than at the intermediate or caudal levels. In addition to the lateral surface, there was a striking difference in the dorsomedial aspects of the SN between PD and control subjects. In control subjects, a brighter signal region was observed along the dorsomedial surface of the lateral portion of SN, whereas in PD subjects, this region was observed as a dark region containing a hypointense signal in T(2)*-weighted images. The measurement of SN volumes, normalized to the intracranial volumes, showed higher values in PD subjects than in control subjects. INTERPRETATION: This study demonstrates that 3D 7T MRI can definitively visualize anatomical alterations occurring in the SN of PD subjects. Further pathological studies are required to elucidate the nature of these anatomical alterations.

Plasma neurofilament light-chain and phosphorylated tau as biomarkers of disease severity in Huntington's disease: Korean cohort data.

OBJECTIVE: To investigate neurofilament light chain (NfL), phosphorylated tau (p-Tau) and total tau (t-Tau) as plasma markers for clinical severity in Korean Huntington's disease (HD) cohort. METHODS: Genetically-confirmed 67 HD patients participated from 13 referral hospitals in South Korea. The subjects were evaluated with the Unified Huntington's Disease Rating Scale (UHDRS), total motor score (TMS) and total functional capacity (TFC), Mini-Mental Status Examination (K-MMSE), Montreal Cognitive Assessment (MoCA-K), and Beck's depression inventory (K-BDI). We measured plasma NfL, p-Tau and t-Tau concentrations using single-molecule array (SIMOA) assays. Stages of HD were classified based on UHDRS-TFC score and plasma markers were analyzed for correlation with clinical severity scales. RESULTS: Plasma NfL was elevated in both 6 premanifest and 61 full manifest HD patients compared to the reference value, which increased further from premanifest to manifest HD groups. The NfL level was not significantly correlated with UHDRS TMS or TFC scores in manifest HD patients. Plasma p-Tau was also elevated in HD patients (p = 0.038). The level was the highest in stage III-V HD (n = 30) group (post-hoc p < 0.05). The p-Tau was correlated with UHDRS TFC scores (adjusted p = 0.002). Plasma t-Tau neither differed among the groups nor associated with any clinical variables. CONCLUSIONS: This study supports plasma NfL being a biomarker for initial HD manifestation in Korean cohort, and a novel suggestion of plasma p-Tau as a potential biomarker reflecting the clinical severity in full-manifest HD.

Anodal Transcranial Direct Current Stimulation Could Modulate Cortical Excitability and the Central Cholinergic System in Akinetic Rigid-Type Parkinson's Disease: Pilot Study.

Background: Transcranial direct current stimulation (tDCS) is a non-invasive technique that has been widely studied as an alternative treatment for Parkinson's disease (PD). However, its clinical benefit remains unclear. In this study, we aimed to investigate the effect of tDCS on the central cholinergic system and cortical excitability in mainly akinetic rigid-type patients with PD. Methods: In total, 18 patients with PD were prospectively enrolled and underwent 5 sessions of anodal tDCS on the M1 area, which is on the contralateral side of the dominant hand. We excluded patients with PD who had evident resting tremor of the hand to reduce the artifact of electrophysiologic findings. We compared clinical scales reflecting motor, cognitive, and mood symptoms between pre- and post-tDCS. Additionally, we investigated the changes in electrophysiologic parameters, such as short latency afferent inhibition (SAI) (%), which reflects the central cholinergic system. Results: The United Parkinson's Disease Rating Scale Part 3 (UPDRS-III), the Korean-Montreal Cognitive Assessment (MoCA-K), and Beck Depression Inventory (BDI) scores were significantly improved after anodal tDCS (p < 0.01, p < 0.01, and p < 0.01). Moreover, motor evoked potential amplitude ratio (MEPAR) (%) and integrated SAI showed significant improvement after tDCS (p < 0.01 and p < 0.01). The mean values of the change in integrated SAI (%) were significantly correlated with the changes in UPDRS-III scores; however, the MoCA-K and BDI scores did not show differences. Conclusions: Anodal tDCS could influence the central cholinergic system, such as frontal cortical excitability and depression in PD. This mechanism could underlie the clinical benefit of tDCS in patients with PD.

Cardiac sympathetic denervation could be associated with dysphagia in Parkinson's disease.

Background: Dysphagia is an important non-motor symptom that is closely associated with quality of living and mortality in Parkinson's disease (PD). However, the pathophysiology of dysphagia in PD remains inconclusive. We tried to confirm whether the occurrence of dysphagia could be related to sympathetic degeneration using cardiac 123I-metaiodobenzylguanidine (MIBG) scintigraphy. Methods: We prospectively recruited 27 PD patients and classified them into two groups (PD with dysphagia vs. PD without dysphagia) by Swallowing Disturbance Questionnaire (SDQ) score and compared the clinical characteristics, videofluoroscopic swallowing study (VFSS) findings and parameters from cardiac MIBG scintigraphy. Results: The mean early and late H/M ratios were significantly lower in the PD with dysphagia group than those in the PD without dysphagia group (1.39 ± 0.21 vs. 1.86 ± 0.21, p < 0.01; 1.26 ± 0.18 vs. 1.82 ± 0.29, p < 0.01). In the correlation analysis, both the early and late H/M ratios were negatively correlated with the SDQ score and total VDS score (r = -0.65, p < 0.01; r = -0.53, p < 0.01; r = -0.65, p < 0.01, r = -0.58, p < 0.01). Conclusion: We confirmed that cardiac sympathetic denervation might be associated with the presence and severity of dysphagia. This finding indicates that dysphagia in PD could be associated with a nondopaminergic mechanism.

Reactive microglia and mitochondrial unfolded protein response following ventriculomegaly and behavior defects in kaolin-induced hydrocephalus.

Ventriculomegaly induced by the abnormal accumulation of cerebrospinal fluid (CSF) leads to hydrocephalus, which is accompanied by neuroinflammation and mitochondrial oxidative stress. The mitochondrial stress activates mitochondrial unfolded protein response (UPRmt), which is essential for mitochondrial protein homeostasis. However, the association of inflammatory response and UPRmt in the pathogenesis of hydrocephalus is still unclear. To assess their relevance in the pathogenesis of hydrocephalus, we established a kaolin-induced hydrocephalus model in 8-week-old male C57BL/6J mice and evaluated it over time. We found that kaolin-injected mice showed prominent ventricular dilation, motor behavior defects at the 3-day, followed by the activation of microglia and UPRmt in the motor cortex at the 5-day. In addition, PARP-1/NF-κB signaling and apoptotic cell death appeared at the 5-day. Taken together, our findings demonstrate that activation of microglia and UPRmt occurs after hydrocephalic ventricular expansion and behavioral abnormalities which could be lead to apoptotic neuronal cell death, providing a new perspective on the pathogenic mechanism of hydrocephalus. [BMB Reports 2022; 55(4): 181-186].