Animal models in the study of Alzheimer's disease and Parkinson's disease: A historical perspective

Jiaohong pills attenuate neuroinflammation and amyloid-β protein-induced cognitive deficits by modulating the mitogen-activated protein kinase/nuclear factor kappa-B pathway

BACKGROUND

Jiaohong pills (JHP) consist of Pericarpium Zanthoxyli (PZ) and Radix Rehmanniae, two herbs that have been extensively investigated over many years due to their potential protective effects against cognitive decline and memory impairment. However, the precise mechanisms underlying the beneficial effects remain elusive. Here, research studies were conducted to investigate and validate the therapeutic effects of JHP on Alzheimer's disease.

METHODS

BV-2 cell inflammation was induced by lipopolysaccharide. AD mice were administered amyloid-β (Aβ). Behavioral experiments were used to evaluate learning and memory ability. The levels of nitric oxide (NO), tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), and interleukin-10 (IL-10) were detected using enzyme-linked immunosorbent assay (ELISA). The protein expressions of inducible nitric oxide synthase (iNOS) and the phosphorylation level of mitogen-activated protein kinase (MAPK) and nuclear factor kappa-B (NF-κB) were detected using Western blot. Nissl staining was used to detect neuronal degeneration.

RESULTS

The results demonstrated that an alcoholic extract of PZ significantly decreased the levels of NO, IL-1β, TNF-α, and iNOS; increased the expression level of IL-10; and significantly decreased the phosphorylation levels of MAPK and NF-κB. These inhibitory effects were further confirmed in the AD mouse model. Meanwhile, JHP improved learning and memory function in AD mice, reduced neuronal damage, and enriched the Nissl bodies in the hippocampus. Moreover, IL-1β and TNF-α in the cortex were significantly downregulated after JHP administration, whereas IL-10 showed increased expression.

CONCLUSIONS

It was found that JHP reduced neuroinflammatory response in AD mice by targeting the MAPK/NF-κB signaling pathway.

Glutamate Receptors and C-ABL Inhibitors: A New Therapeutic Approach for Parkinson's Disease

Parkinson's disease (PD) is the second-most prevalent central nervous system (CNS) neurodegenerative condition. Over the past few decades, suppression of BCR-Abelson tyrosine kinase (c-Abl), which serves as a marker of -synuclein aggregation and oxidative stress, has shown promise as a potential therapy target in PD. c-Abl inhibition has the potential to provide neuroprotection against PD, as shown by experimental results and the first-in-human trial, which supports the strategy in bigger clinical trials. Furthermore, glutamate receptors have also been proposed as potential therapeutic targets for the treatment of PD since they facilitate and regulate synaptic neurotransmission throughout the basal ganglia motor system. It has been noticed that pharmacological manipulation of the receptors can change normal as well as abnormal neurotransmission in the Parkinsonian brain. The review study contributes to a comprehensive understanding of the approach toward the role of c-Abl and glutamate receptors in Parkinson's disease by highlighting the significance and urgent necessity to investigate new pharmacotherapeutic targets. The article covers an extensive insight into the concept of targeting, pathophysiology, and c-Abl interaction with α-synuclein, parkin, and cyclin-dependent kinase 5 (Cdk5). Furthermore, the concepts of Nmethyl- D-aspartate (NMDA), α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPA) receptor, and glutamate receptors are discussed briefly. Conclusion: This review article focuses on in-depth literature findings supported by an evidence-based discussion on pre-clinical trials and clinical trials related to c-Abl and glutamate receptors that act as potential therapeutic targets for PD.

miRNA-137-5p improves spatial memory and cognition in Alzheimer's mice by targeting ubiquitin-specific peptidase 30

BACKGROUND

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder causing progressive dementia. Research suggests that microRNAs (miRNAs) could serve as biomarkers and therapeutic targets for AD. Reduced levels of miR-137 have been observed in the brains of AD patients, but its specific role and downstream mechanisms remain unclear. This study sought to examine the therapeutic potential of miR-137-5p agomir in alleviating cognitive dysfunction induced in AD models and explore its potential mechanisms.

METHODS

This study utilized bioinformatic analysis and a dual-luciferase reporter assay to investigate the relationship between miR-137-5p and ubiquitin-specific peptidase 30 (USP30). In vitro experiments were conducted using SH-SY5Y cells to assess the impact of miR-137-5p on Aβ1-42 neurotoxicity. In vivo experiments on AD mice evaluated the effects of miR-137-5p on cognition, Aβ1-42 deposition, Tau hyperphosphorylation, and neuronal apoptosis, as well as its influence on USP30 levels.

RESULTS

It was discovered that miR-137-5p mimics efficiently counteract Aβ1-42 neurotoxicity in SH-SY5Y cells, a protective effect that is negated by USP30 overexpression. In vivo experiments demonstrated that miR-137-5p enhances the cognition and mobility of AD mice, significantly reducing Aβ1-42 deposition, Tau hyperphosphorylation, and neuronal apoptosis within the hippocampus and cortex regions. Mechanistically, miR-137-5p significantly suppresses USP30 levels in mice, though USP30 overexpression partially buffers against miR-137-5p-induced AD symptom improvement.

CONCLUSION

Our study proposes that miR-137-5p, by instigating the downregulation of USP30, has the potential to act as a novel and promising therapeutic target for AD.

Mammalian Models in Alzheimer's Research: An Update

A form of dementia distinct from healthy cognitive aging, Alzheimer's disease (AD) is a complex multi-stage disease that currently afflicts over 50 million people worldwide. Unfortunately, previous therapeutic strategies developed from murine models emulating different aspects of AD pathogenesis were limited. Consequently, researchers are now developing models that express several aspects of pathogenesis that better reflect the clinical situation in humans. As such, this review seeks to provide insight regarding current applications of mammalian models in AD research by addressing recent developments and characterizations of prominent transgenic models and their contributions to pathogenesis as well as discuss the advantages, limitations, and application of emerging models that better capture genetic heterogeneity and mixed pathologies observed in the clinical situation.

Computational, In Vitro, and In Vivo Models for Nose-to-Brain Drug Delivery Studies

Direct nose-to-brain drug delivery offers the opportunity to treat central nervous system disorders more effectively due to the possibility of drug molecules reaching the brain without passing through the blood-brain barrier. Such a delivery route allows the desired anatomic site to be reached while ensuring drug effectiveness, minimizing side effects, and limiting drug losses and degradation. However, the absorption of intranasally administered entities is a complex process that considerably depends on the interplay between the characteristics of the drug delivery systems and the nasal mucosa. Various preclinical models (in silico, in vitro, ex vivo, and in vivo) are used to study the transport of drugs after intranasal administration. The present review article attempts to summarize the different computational and experimental models used so far to investigate the direct delivery of therapeutic agents or colloidal carriers from the nasal cavity to the brain tissue. Moreover, it provides a critical evaluation of the data available from different studies and identifies the advantages and disadvantages of each model.

New Allosteric Modulators of AMPA Receptors: Synthesis and Study of Their Functional Activity by Radioligand-Receptor Binding Analysis

The synthetic approaches to three new AMPA receptor modulators-derivatives of 1,11-dimethyl-3,6,9-triazatricyclo[7.3.1.1^3,11]tetradecane-4,8,12-trione-had been developed and all steps of synthesis were optimized. The structures of the compounds contain tricyclic cage and indane fragments necessary for binding with the target receptor. Their physiological activity was studied by radioligand-receptor binding analysis using [³H]PAM-43 as a reference ligand, which is a highly potent positive allosteric modulator of AMPA receptors. The results of radioligand-binding studies indicated the high potency of two synthesized compounds to bind with the same targets as positive allosteric modulator PAM-43 (at least on AMPA receptors). We suggest that the Glu-dependent specific binding site of [³H]PAM-43 or the receptor containing this site may be one of the targets of the new compounds. We also suggest that enhanced radioligand binding may indicate the existence of synergistic effects of compounds 11b and 11c with respect to PAM-43 binding to the targets. At the same time, these compounds may not compete directly with PAM-43 for its specific binding sites but bind to other specific sites of this biotarget, changing its conformation and thereby causing a synergistic effect of cooperative interaction. It can be expected that the newly synthesized compounds will also have pronounced effects on the glutamatergic system of the mammalian brain.

Generation and Characterization of the First Murine Model of Alzheimer's Disease with Mutated AβPP Inserted in a BALB/c Background (C.B6/J-APPswe)

BACKGROUND

Numerous mouse models of Alzheimer's disease (AD) are available, but all suffer from certain limitations, thus prompting further attempts. To date, no one model exists with amyloidopathy in a BALB/c strain.

OBJECTIVE

To generate and characterize the C.B6/J-APPswe mouse, a model of AD with a mutated human gene for the amyloid-β protein precursor (AβPP) inserted in a BALB/c background.

METHODS

We analyzed five groups at different ages (3, 6, 9, 12, and 16-18 months) of C.B6/J-APPswe and wild-type mice (50% males and 50% females) for the main hallmarks of AD by western blotting, amyloid-β (Aβ) ELISA, immunocytochemistry, electrophysiology, and behavioral tests.

RESULTS

The C.B6/J-APPswe mouse displays early AβPP and Aβ production, late amyloid plaques formation, high level of tau phosphorylation, synaptic deficits (reduced density and functional impairment due to a reduced post-synaptic responsiveness), neurodegeneration caused by apoptosis and necroptosis/necrosis, microgliosis, astrocytic abnormalities, and sex-related differences in explorative behavior, anxiety-like behavior, and spatial long-term and working memories. Social housing is feasible despite the intra-cage aggressiveness of male animals.

CONCLUSION

C.B6/J-APPswe mice develop most of the distinctive features of AD and is a suitable model for the study of brain atrophy mechanisms and of the differences between males and females in the onset of cognitive/non-cognitive deficits.

Diversity of AMPA Receptor Ligands: Chemotypes, Binding Modes, Mechanisms of Action, and Therapeutic Effects

L-Glutamic acid is the main excitatory neurotransmitter in the central nervous system (CNS). Its associated receptors localized on neuronal and non-neuronal cells mediate rapid excitatory synaptic transmission in the CNS and regulate a wide range of processes in the brain, spinal cord, retina, and peripheral nervous system. In particular, the glutamate receptors selective to α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) also play an important role in numerous neurological disorders and attract close attention as targets for the creation of new classes of drugs for the treatment or substantial correction of a number of serious neurodegenerative and neuropsychiatric diseases. For this reason, the search for various types of AMPA receptor ligands and studies of their properties are attracting considerable attention both in academic institutions and in pharmaceutical companies around the world. This review focuses mainly on the advances in this area published since 2017. Particular attention is paid to the structural diversity of new chemotypes of agonists, competitive AMPA receptor antagonists, positive and negative allosteric modulators, transmembrane AMPA regulatory protein (TARP) dependent allosteric modulators, ion channel blockers as well as their binding sites. This review also presents the studies of the mechanisms of action of AMPA receptor ligands that mediate their therapeutic effects.

The kingdom of the prolyl-isomerase Pin1: The structural and functional convergence and divergence of Pin1

More than 20 years since its discovery, our understanding of Pin1 function in various diseases continues to improve. Pin1 plays a crucial role in pathogenesis and has been implicated in metabolic disorders, cardiovascular diseases, inflammatory diseases, viral infection, cancer and neurodegenerative diseases such as Alzheimer’s, Parkinson’s and Huntington’s disease. In particular, the role of Pin1 in neurodegenerative diseases and cancer has been extensively studied. Our understanding of Pin1 in cancer also led to the development of cancer therapeutic drugs targeting Pin1, with some currently in clinical trial phases. However, identifying a Pin1-specific drug with good cancer therapeutic effect remains elusive, thus leading to the continued efforts in Pin1 research. The importance of Pin1 is highlighted by the presence of Pin1 orthologs across various species: from vertebrates to invertebrates and Kingdom Animalia to Plantae. Among these Pin1 orthologs, their sequence and structural similarity demonstrate the presence of conservation. Moreover, their similar functionality between species further highlights the conservancy of Pin1. As researchers continue to unlock the mysteries of Pin1 in various diseases, using different Pin1 models might shed light on how to better target Pin1 for disease therapeutics. This review aims to highlight the various Pin1 orthologs in numerous species and their divergent functional roles. We will examine their sequence and structural similarities and discuss their functional similarities and uniqueness to demonstrate the interconnectivity of Pin1 orthologs in multiple diseases.