Dysfunction of norepinephrine and its metabolites in Alzheimer's dementia - A review with meta-analysis

Erzhi pill promotes norepinephrine synthesis in locus coeruleus through ERβ-TFAP2A-TH plays a neuroprotective role

ETHNOPHARMACOLOGICAL RELEVANCE

Erzhi Pill (EZP), a classical Chinese herbal formula for yin-nourishing and kidney-tonifying, has been traditionally prescribed for insomnia and amnesia, and shows therapeutic potential for Alzheimer's disease (AD). However, its active components and precise mechanisms of action against AD remain elusive.

AIM OF THE STUDY

This study aimed to identify the key active components and molecular targets of EZP responsible for improving cognitive dysfunction and to elucidate its underlying mechanisms.

MATREIALS AND METHODS

Behavioral and histomorphological analyses will be used to validate the efficacy of EZP in ameliorating cognitive impairment in lipopolysaccharide (LPS)-induced models. Untargeted metabolomics characterized metabolic profile alterations in the locus coeruleus (LC), while targeted metabolomics focused on specific metabolic pathways. Microdialysis coupled with high-resolution mass spectrometry (HR-MS) analyzed EZP's chemical components in LC dialysates. Network pharmacology and molecular docking predicted potential targets, with binding affinities validated by surface plasmon resonance (SPR). Molecular biology techniques were employed to investigate relevant signaling pathways.

RESULTS

EZP significantly improved learning and memory capabilities in LPS-induced models, accompanied by enhanced neuronal activity. Metabolomic profiling revealed that EZP exerted its effects primarily through modulation of alanine, aspartate, and glutamate metabolism pathways, as well as phenylalanine and tyrosine metabolic networks. Specifically, EZP treatment resulted in decreased tyrosine (Tyr) levels and increased norepinephrine (NE) concentrations in the LC. Western blot analysis further demonstrated upregulated expression of tyrosine hydroxylase (TH) and dopamine β-hydroxylase (DβH) proteins in LC tissues. Phytochemical analysis identified 45 prototype components and 14 metabolites in EZP, among which apigenin and wedelolactone were characterized as potential bioactive ingredients. Network pharmacology combined with molecular docking revealed estrogen receptor β (ERβ) as a critical target mediating EZP's anti-AD effects. SPR validated stronger binding affinity of apigenin and wedelolactone to ERβ compared with G-protein-coupled receptor 30 (GPR30). Mechanistic studies showed that these compounds activated ERβ signaling, restored TFAP2A/TH transcriptional activity, and promoted NE biosynthesis, thereby ameliorating cognitive deficits in AD models.

CONCLUSION

This study not only elucidates that EZP ameliorates cognitive dysfunction in AD)via the ERβ-TFAP2A/TH signaling pathway but also proposes NE augmentation as a novel therapeutic strategy for AD management.

Autonomic dysfunction in neurodegenerative disease

In addition to their more studied cognitive and motor effects, neurodegenerative diseases are also associated with impairments in autonomic function - the regulation of involuntary physiological processes. These autonomic impairments manifest in different ways and at different stages depending on the specific disease. The neural networks responsible for autonomic regulation in the brain and body have characteristics that render them particularly susceptible to the prion-like spread of protein aggregation involved in neurodegenerative diseases. Specifically, the axons of these neurons - in both peripheral and central networks - are long and poorly myelinated axons, which make them preferential targets for pathological protein aggregation. Moreover, cortical regions integrating information about the internal state of the body are highly connected with other brain regions, which increases the likelihood of intersection with pathological pathways and prion-like spread of abnormal proteins. This leads to an autonomic 'signature' of dysfunction, characteristic of each neurodegenerative disease, that is linked to the affected networks and regions undergoing pathological aggregation.

Validation of a Sensitive, Simple and High-Throughput UPLC-MS/MS Method for Quantification of Catecholamines and Their Metabolites in Serum and Urine: Application in Clinical Analysis

A sensitive, simple and high-throughput UPLC-MS/MS method has been validated for the simultaneous quantification of catecholamines and their metabolite levels in serum and urine for clinical applications. The analytes and their isotope-labeled internal standards were extracted using a 96-well solid-phase extraction cartridge and then separated on an HSS PFP column with a 4-min gradient elution. The linear ranges were 10 ~ 5000 pg/mL for dopamine (DA), epinephrine (E), metanephrine (MN) and normetanephrine (NMN), 2 ~ 5000 pg/mL for norepinephrine (NE), and 2 ~ 2000 pg/mL for 3-methoxytyramine (3-MT). The limits of quantification were 10 pg/mL for DA and E, 5 pg/mL for MN and NMN, 2 pg/mL for 3-MT, and 20 pg/mL for NE. The accuracy was excellent with relative bias all within 10%, and the intra-day and inter-day precision values were also within the tolerance range (RSD < 15%), and the recovery was in the range of 86.0-107.7% with RSD < 15%. After correction using IS, no significant matrix effects were observed. Moreover, the discrepancies in the analyte levels between plasma and serum were investigated for the first time. The analyte levels in the two biological matrices exhibited a significant correlation (P < 0.001) and significant differences (P < 0.001).

Fading Blue: Exploring the Causes of Locus Coeruleus Damage Across the Lifespan

Locus Coeruleus (LC) is a brain nucleus that is involved in a variety of key functions (ranging from attention modulation to sleep-wake cycle regulation, to memory encoding); its proper function is necessary both during brain development and for brain integrity maintenance, and both at the microscale and macroscale level. Due to their specific intrinsic and extrinsic features, LC cells are considered particularly susceptible to damage concerning a variety of insults. This explains LC involvement in degenerative diseases not only in adults (in the context of neurodegenerative disease, mainly), but also in children (in relation to early hypoxic damage and Down's Syndrome, among others). In this narrative review, we dissect the potential mechanisms through which LC is affected in different diseases, with a special emphasis on the high rate of activity it is subjected to and the oxidative stress associated with it. Further research aimed at deepening our understanding of these mechanisms is needed to enable the development of potential strategies in the future that could slow down LC degeneration in subjects predisposed to specific brain disorders.

Effects of nanoplastic exposure during pregnancy and lactation on neurodevelopment of rat offspring

Microplastics have emerged as a prominent global environmental contaminant, and they have been found in both human placenta and breast milk. However, the potential effects and mechanisms of maternal exposure to microplastics at various gestational stages on offspring neurodevelopment remain poorly understood. This investigation delves into the potential neurodevelopmental ramifications of maternal exposure to polystyrene nanoplastics (PS-NPs) during distinct phases of pregnancy and lactation. Targeted metabolomics shows that co-exposure during both pregnancy and lactation primarily engendered alterations in monoamine neurotransmitters within the cortex and amino acid neurotransmitters within the hippocampus. After prenatal exposure to PS-NPs, fetal rats showed appreciably diminished cortical thickness and heightened cortical cell proliferation. However, this exposure did not affect the neurodifferentiation of radial glial cells and intermediate progenitor cells. In addition, offspring are accompanied by disordered neocortical migration, typified by escalated superficial layer neurons proliferation and reduced deep layer neurons populations. Moreover, the hippocampal synapses showed significantly widened synaptic clefts and diminished postsynaptic density. Consequently, PS-NPs culminated in deficits in anxiolytic-like behaviors and spatial memory in adolescent offspring, aligning with concurrent neurotransmitter and synaptic alterations. In conclusion, this study elucidates the sensitive windows of early-life nanoplastic exposure and the consequential impact on offspring neurodevelopment.

The Role of Catecholamines in the Pathogenesis of Diseases and the Modified Electrodes for Electrochemical Detection of Catecholamines: A Review

Catecholamines (CAs), which include adrenaline, noradrenaline, and dopamine, are neurotransmitters and hormones that critically regulate the cardiovascular system, metabolism, and stress response in the human body. The abnormal levels of these molecules can lead to the development of various diseases, including pheochromocytoma and paragangliomas, Alzheimer's disease, and Takotsubo cardiomyopathy. Due to their low cost, high sensitivity, flexible detection strategies, ease of integration, and miniaturization, electrochemical techniques have been extensively employed in the detection of CAs, surpassing traditional analytical methods. Electrochemical detection of CAs in real samples is challenging due to the tendency of poisoning electrode. Chemically modified electrodes have been widely used to solve the problems of poor sensitivity and selectivity faced by bare electrodes. There are a few articles that provide an overview of electrochemical detection and efficient enrichment of CAs, but there is a dearth of updates on the role of CAs in the pathogenesis of diseases. Additionally, there is still a lack of systematic synthesis with a focus on modified electrodes for electrochemical detection. Thus, this review provides a summary of the recent clinical pathogenesis of CAs and the modified electrodes for electrochemical detection of CAs published between 2017 and 2022. Moreover, challenges and future perspectives are also highlighted. This work is expected to provide useful guidance to researchers entering this interdisciplinary field, promoting further development of CAs pathogenesis, and developing more novel chemically modified electrodes for the detection of CAs.