Copper is a trace element whose electronic configuration provides it with essential structural and catalytic functions. However, in excess, both its high protein affinity and redox-catalyzing properties can lead to hazardous consequences. In addition to promoting oxidative stress, copper is gaining interest for its effects on neurotransmission through modulation of GABAergic and glutamatergic receptors and interaction with the dopamine reuptake transporter. The aim of the present study was to investigate the effects of copper overexposure on the levels of dopamine, noradrenaline, and serotonin, or their main metabolites in rat\'s striatum extracellular fluid. Copper was injected intraperitoneally using our previously developed model, which ensured striatal overconcentration (2 mg CuCl2/kg for 30 days). Subsequently, extracellular fluid was collected by microdialysis on days 0, 15, and 30. Dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA), and noradrenaline (NA) levels were then determined by HPLC coupled with electrochemical detection. We observed a significant increase in the basal levels of DA and HVA after 15 days of treatment (310% and 351%), which was maintained after 30 days (358% and 402%), with no significant changes in the concentrations of 5-HIAA, DOPAC, and NA. Copper overload led to a marked increase in synaptic DA concentration, which could contribute to the psychoneurological alterations and the increased oxidative toxicity observed in Wilson\'s disease and other copper dysregulation states.

Parkinson\'s disease (PD), which is the second most common neurodegenerative disorder, is characterized by progressive movement impairment and loss of midbrain dopaminergic neurons in the substantia nigra. Although mutations in TMEM230 are linked to familial PD, the pathogenic mechanism underlying TMEM230-associated PD remains to be elucidated. To explore the effect of TMEM230 depletion in vivo, we created TMEM230 knockout rats using CRISPR-Cas9 technology. TMEM230 knockout rats did not exhibit any core features of PD, including impaired motor function, loss of dopaminergic neurons in the substantia nigra, or altered expression of proteins related to autophagy, the Rab family, or vesicular trafficking. In addition, no glial reactions were observed in TMEM230 knockout rats. These results indicate that depletion of TMEM230 may not lead to dopaminergic neuron degeneration in rats, further supporting that PD-associated TMEM230 mutations lead to dopaminergic neuron death by gain-of-toxic function.

Multiple reference panels of a given tissue or multiple tissues often exist, and multiple regression methods could be used for training gene expression imputation models for transcriptome-wide association studies (TWAS). To leverage expression imputation models (i.e., base models) trained with multiple reference panels, regression methods, and tissues, we develop a Stacked Regression based TWAS (SR-TWAS) tool which can obtain optimal linear combinations of base models for a given validation transcriptomic dataset. Both simulation and real studies show that SR-TWAS improves power, due to increased training sample sizes and borrowed strength across multiple regression methods and tissues. Leveraging base models across multiple reference panels, tissues, and regression methods, our real studies identify 6 independent significant risk genes for Alzheimer\'s disease (AD) dementia for supplementary motor area tissue and 9 independent significant risk genes for Parkinson\'s disease (PD) for substantia nigra tissue. Relevant biological interpretations are found for these significant risk genes.

Data on the participation of microbiota in the development of Parkinson\'s disease allow us to discuss the ability of bacterial preparations to influence the processes leading to neurodegeneration. We studied the effect of oral administration of Limosilactobacillus fermentum U-21 lyophilisate on a model of Parkinson\'s disease in rats induced by combined intranigral injection of LPS and systemic administration of paraquat. The toxins significantly increased the number of missteps in the \"narrowing beam walking\" test, but a tendency to a decrease in this parameter was shown after treatment with U-21. It should be noted that U-21 did not reduce the neuronal death in the substantia nigra, but mitigated the inflammatory glial response, decreased the accumulation of phosphorylated α-synuclein and complement protein C3. Our study demonstrated the efficiency of the combined model of parkinsonism and reduction of proinflammatory changes under the influence of pharmabiotic without changes in the nigral neuronal death and motor deficits.

BACKGROUND: It is debatable whether the area of substantia nigra hyperechogenicity (SN+) in transcranial sonography (TCS) is related to Parkinson\'s disease (PD) severity. Iron deposition, which is associated with the formation of SN+, may have different effects on dopamine nerve function as PD progresses. However, little research has explored the association between the SN + area and disease severity of PD in stages.
METHODS: 612 PD patients with sufficient bone window were retrospectively included from a PD database, and disease severity was assessed by the Unified Parkinson\'s Disease Rating Scale (UPDRS) scores. Based on the Hoehn and Yahr (H-Y) scale, we classified the patients into seven groups (H-Y stage 1, 1.5, 2, 2.5, 3, 4, and 5) and then analyzed the correlations between the SN + area and the UPDRS scores separately.
RESULTS: Our results indicated a U-shaped relationship between the initial-SN + area and disease severity in PD: In the H-Y stage 1 group, the initial-SN + area was negatively correlated with the UPDRS total score (r = - 0.456, p < 0.001) and UPDRS-III score (r = - 0.497, p < 0.001). No correlation was observed in the groups of H-Y stages 1.5, 2, and 2.5. In the groups of H-Y stage ≥ 3, the initial-SN + area was positively correlated with the UPDRS total score and UPDRS-III score, with strongest correlation in the H-Y stage 5 group (all p values < 0.05). Moreover, the larger SN + area and average SN + area showed a similar evolutionary trend of correlation with UPDRS total score and UPDRS-III score.
CONCLUSIONS: Our study indicated a U-shaped correlation between the SN + area with the UPDRS total score and UPDRS-III score as H-Y stage progressed. The evolution of the correlation may reflect the evolution of underlying pathological mechanisms related to iron deposition in the substantia nigra.

A hallmark of Parkinson\'s disease is the specific degeneration of dopaminergic neurons in the substantia nigra pars compacta. Interestingly, not all of these neurons are affected to the same extent. Studies revealed that neurons located more ventrally within the substantia nigra pars compacta have a higher prevalence to degenerate than those located in the dorsal tier. The underlying reasons for this selective neuronal vulnerability are still unknown. The aim of the present study was to gain a better understanding of molecular differences between these two neuronal subpopulations that may explain the selective neuronal vulnerability within the human substantia nigra. For this purpose, the neurons from the ventral as well as dorsal tier of the substantia nigra were specifically isolated out of neuropathologically unremarkable human substantia nigra sections with laser microdissection. Following, their proteome was analyzed by data independent acquisition mass spectrometry. The samples were analysed donor-specifically and not pooled for this purpose. A total of 5,391 proteins were identified in the substantia nigra. Of these, 2,453 proteins could be quantified in 100% of the dorsal tier samples. 1,629 could be quantified in 100% of the ventral tier samples. Nine proteins were differentially regulated with a log2 value ≥0.5 and a Qvalue ≤0.05. Of these 7 were higher abundant in the dorsal tier and 2 higher in the ventral tier. These proteins are associated with the cytoskeleton, neuronal plasticity, or calcium homeostasis. With these findings a deeper understanding can be gained of the selective neuronal vulnerability within the substantia nigra and of protective mechanisms against neurodegeneration in specific neuronal subpopulations.

Agyrophilic grains (AGs) are age-related limbic-predominant lesions in which four-repeat tau is selectively accumulated. Because previous methodologically heterogeneous studies have demonstrated inconsistent findings on the relationship between AGs and dementia, whether AGs affect cognitive function remains unclear. To address this question, we first comprehensively evaluated the distribution and quantity of Gallyas-positive AGs and the severity of neuronal loss in the limbic, neocortical, and subcortical regions in 30 cases of pure argyrophilic grain disease (pAGD) in Braak stages I-IV and without other degenerative diseases, and 34 control cases that had only neurofibrillary tangles with Braak stages I-IV and no or minimal Aβ deposits. Then, we examined whether AGs have independent effects on neuronal loss and dementia by employing multivariate ordered logistic regression and binomial logistic regression. Of 30 pAGD cases, three were classified in diffuse form pAGD, which had evident neuronal loss not only in the limbic region but also in the neocortex and subcortical nuclei. In all 30 pAGD cases, neuronal loss developed first in the amygdala, followed by temporo-frontal cortex, hippocampal CA1, substantia nigra, and finally, the striatum and globus pallidus with the progression of Saito AG stage. In multivariate analyses of 30 pAGD and 34 control cases, the Saito AG stage affected neuronal loss in the amygdala, hippocampal CA1, temporo-frontal cortex, striatum, globus pallidus, and substantia nigra independent of the age, Braak stage, and limbic-predominant age-related TDP-43 encephalopathy (LATE-NC) stage. In multivariate analyses of 23 pAGD and 28 control cases that lacked two or more lacunae and/or one or more large infarctions, 100 or more AGs per × 400 visual field in the amygdala (OR 10.02, 95% CI 1.12-89.43) and hippocampal CA1 (OR 12.22, 95% CI 1.70-87.81), and the presence of AGs in the inferior temporal cortex (OR 8.18, 95% CI 1.03-65.13) affected dementia independent of age, moderate Braak stages (III-IV), and LATE-NC. Given these findings, the high density of limbic AGs and the increase of AGs in the inferior temporal gyrus may contribute to the occurrence of dementia through neuronal loss, at least in cases in a low to moderate Braak stage.

Parkinson\'s disease (PD) is characterized by a long prodromal period, during which patients often have sleep disturbances. The histaminergic system and circadian rhythms play an important role in the regulation of the sleep-wake cycle. Changes in the functioning of these systems may be involved in the pathogenesis of early stages of PD and may be age-dependent. Here, we have analyzed changes in the expression of genes associated with the regulation of the sleep-wake cycle (Hnmt, Hrh1, Hrh3, Per1, Per2, and Chrm3) in the substantia nigra (SN) and striatum of normal male mice of different ages, as well as in young and adult male mice with an MPTP-induced model of the early symptomatic stage (ESS) of PD. Age-dependent expression analysis in normal mouse brain tissue revealed changes in Hrh3, Per1, Per2, and Chrm3 genes in adult mice relative to young mice. When gene expression was examined in mice with the MPTP-induced model of the ESS of PD, changes in the expression of all studied genes were found only in the SN of adult mice with the ESS model of PD. These data suggest that age is a significant factor influencing changes in the expression of genes associated with sleep-wake cycle regulation in the development of PD.

Aggregation of the protein α-Synuclein (αSyn) is a hallmark of Parkinson\'s disease (PD), dementia with Lewy bodies (DLB) and multiple systems atrophy, and alleviating the extent of αSyn pathology is an attractive strategy against neurodegeneration. The engineered binding protein β-wrapin AS69 binds monomeric αSyn. AS69 reduces primary and secondary nucleation as well as fibril elongation in vitro. It also mitigates aSyn pathology in a mouse model based on intrastriatal injection of aSyn pre-formed fibrils (PFFs). Since the PFF-based model does not represent all aspects of PD, we tested here whether AS69 can reduce neurodegeneration resulting from αSyn overexpression. Human A53T-αSyn was overexpressed in the mouse Substantia nigra (SN) by using recombinant adeno-associated viral vector (rAAV). AS69 was also expressed by rAAV transduction. Behavioral tests and immunofluorescence staining were used as outcomes. Transduction with rAAV-αSyn resulted in αSyn pathology as reported by phospho-αSyn staining and caused degeneration of dopaminergic neurons in the SN. The co-expression of rAAV-AS69 did not reduce αSyn pathology or the degeneration of dopaminergic neurons. We conclude that αSyn monomer binding by rAAV-AS69 was insufficient to protect from aSyn pathology resulting from αSyn overexpression.

The pursuit of drugs and methods to safeguard dopaminergic neurons holds paramount importance in Parkinson\'s disease (PD) research. Benfotiamine (BFT) has demonstrated neuroprotective properties, yet its precise mechanisms in PD remain elusive. This study investigated BFT\'s potential protective effects against dopamine neuron damage in a PD animal model and the underlying mechanisms. The PD mouse model was induced by 5 consecutive MPTP injections, followed by BFT intervention for 28 days. Motor deficits were assessed via pole test, hang test, gait analysis, and open field test, while dopaminergic neuron damage was evaluated through Immunofluorescence, Nissl staining, and Western blot analysis of Tyrosine Hydroxylase (TH) in the substantia nigra and striatum. High Performance Liquid Chromatography quantified dopamine (DA) levels and its metabolites. Genetic pathways were explored using RNA-seq and bioinformatics analysis on substantia nigra tissues, confirmed by qPCR. Activation of the Nrf2 pathway was examined through nuclear translocation and expression of downstream antioxidant enzymes HO-1, GCLM, and NQO1 at mRNA and protein levels. Additionally, measurements of MDA content, GSH activity, and SOD activity were taken in the substantia nigra and striatum. BFT administration improved motor function and protected against dopaminergic neuron degeneration in MPTP mice, with partial recovery in TH expression and DA levels. RNA-seq analysis revealed distinct effects of BFT and the NLRP3 inhibitor MCC950 on Parkinson-related pathways and genes. Control of Nrf2 proved crucial for BFT, as it facilitated Nrf2 movement to the nucleus, upregulating antioxidant genes and enzymes while mitigating oxidative damage. This study elucidates BFT\'s neuroprotective effects in a PD mouse model via Nrf2-mediated antioxidant mechanisms and gene expression modulation, underscoring its potential as a therapeutic agent for PD.