Reduced platelet 5-HT content is associated with rest tremor in Parkinson's disease.

INTRODUCTION: Parkinson's disease (PD) is highly heterogeneous in manifestations and pathogenesis. Serotonergic neurotransmitter system dysfunction is frequently implicated in PD tremor. Serotonin (5-HT) content in platelets is highly correlated with that in cerebrospinal fluid. In this study, we aimed to understand whether and how platelet 5-HT content reflects tremor in PD. METHOD: A total of 139 Chinese PD patients met with inclusion criteria were recruited. Motor and non-motor scores, and disease severity were evaluated. Patients were classified into subtypes of tremor-dominant (TD) and non-tremor-dominant (NTD). Peripheral platelets were isolated, and platelet 5-HT levels were measured. RESULTS: Platelet 5-HT content was lower in PD patients of TD subtype than in NTD subtype. Multifactor risk analysis showed that this lower content was independently associated with the TD phenotype. Platelet 5-HT level was inversely correlated with total tremor score, rest tremor amplitude score, rest tremor constancy score, and index of rest tremor, but not with postural tremor score, and kinetic tremor score. CONCLUSION: The cross-sectional study demonstrates that reduced platelet 5-HT content is associated with PD rest tremor. Our results support the involvement of serotonergic disturbance in PD rest tremor and indicate that 5-HT reduction can be manifested in peripheral platelets.

ALDH1A1 Genetic Variations May Modulate Risk of Parkinson's Disease in Han Chinese Population.

Background: Studies in animal models have suggested that aldehyde dehydrogenase 1 (encoded by ALDH1A1) protects against Parkinson's disease (PD) by reducing toxic metabolites of dopamine. Herein we aimed to investigate whether ALDH1A1 was genetically associated with PD susceptibility in humans. Methods: A Han Chinese population of 1,039 subjects was recruited to analyze six tag-single nucleotide polymorphisms (SNPs), followed by haplotype analyses and variants interaction analyses. Real-time PCR was used to analyze mRNA levels of ALDH1A1 in peripheral blood of 42 subjects. Results: The tag-SNP rs7043217 of ALDH1A1 was significantly associated with PD susceptibility with the T serving as a risk allele (genotype frequency, P = 0.030; allele frequency, P = 0.013, OR = 1.258, 95% CI = 1.050-1.508). Multiple haplotypes were linked to abnormalities of PD risk, topped by a 4-SNP GGTA module in the order of rs4646547, rs1888202, rs7043217, and rs647880 (P = 9.610 × 10-8, OR = 6.420, 95% CI = 2.944-13.998). Interaction analyses showed that a simultaneous presence of the CC genotype of rs7043217 and the TT genotype of ALDH2 variant rs4767944 conferred an elevated protection against PD (P = 4.68 × 10-4, OR = 0.378, 95% CI = 0.219-0.652). The mRNA expression of ALDH1A1 showed a trend of reduction (P = 0.084) in PD patients compared to the controls. Conclusion: Our results provide novel genetic insights into the role of ALDH1 in PD pathogenesis.

Differential and paradoxical roles of new-generation antidepressants in primary astrocytic inflammation.

BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) are commonly used new-generation drugs for depression. Depressive symptoms are thought to be closely related to neuroinflammation. In this study, we used up-to-date protocols of culture and stimulation and aimed to understand how astrocytes respond to the antidepressants. METHODS: Primary astrocytes were isolated and cultured using neurobasal-based serum-free medium. The cells were treated with a cytokine mixture comprising complement component 1q, tumor necrosis factor α, and interleukin 1α with or without pretreatments of antidepressants. Cell viability, phenotypes, inflammatory responses, and the underlying mechanisms were analyzed. RESULTS: All the SSRIs, including paroxetine, fluoxetine, sertraline, citalopram, and fluvoxamine, show a visible cytotoxicity within the range of applied doses, and a paradoxical effect on astrocytic inflammatory responses as manifested by the promotion of inducible nitric oxide synthase (iNOS) and/or nitric oxide (NO) and the inhibition of interleukin 6 (IL-6) and/or interleukin 1ß (IL-1ß). The SNRI venlafaxine was the least toxic to astrocytes and inhibited the production of IL-6 and IL-1ß but with no impact on iNOS and NO. All the drugs had no regulation on the polarization of astrocytic A1 and A2 types. Mechanisms associated with the antidepressants in astrocytic inflammation route via inhibition of JNK1 activation and STAT3 basal activity. CONCLUSIONS: The study demonstrated that the antidepressants possess differential cytotoxicity to astrocytes and function differently, also paradoxically for the SSRIs, to astrocytic inflammation. Our results provide novel pieces into understanding the differential efficacy and tolerability of the antidepressants in treating patients in the context of astrocytes.

Prevalence of Alzheimer's Disease and Parkinson's Disease in China: An Updated Systematical Analysis.

Background: Alzheimer's disease (AD) and Parkinson's disease (PD) are two major neurodegenerative diseases worldwide. Demographic aging is in rapid progress in China. Up-to-date estimates of AD and PD prevalence have not been provided. Methods: Studies that reported the prevalence of AD and PD in China were identified via a systematic database search from 1985 to 2018. Meta-analysis, local polynomial regression and autoregressive integrated moving average model were used for analyses. Results: A total of 99 studies were included in the study with populations of 385,312 and 227,228, respectively for AD and PD. The overall prevalence of AD and PD following age standardization was 3.20% [95% confidence interval (CI) = 3.17-3.23] and 1.06% (95% CI = 1.02-1.10), respectively in individuals over 60 years old. The rates increased drastically for every 10-years increment of age. The yearly prevalence of AD was predicted to increase from 3.81 to 6.17% in the next 5 years. Significant differences were observed between genders [male to female odds ratio (OR) for AD = 0.57, 95% CI = 0.51-0.64; OR for PD = 1.25, 95% CI = 1.06-1.46], and between education levels (Illiterate to non-illiterate OR for AD = 2.99, 95% CI = 2.38-3.75), but not between urban and rural settings. Conclusion: Our results provide an updated insight into the epidemiology of AD and PD in China and their associated rates and ratios. The findings may facilitate China policy makers and health professionals mitigate the related health issues.