Piperine promotes PI3K/AKT/mTOR-mediated gut-brain autophagy to degrade α-Synuclein in Parkinson's disease rats

Investigating the Interplay Between the Nrf2/Keap1/HO-1/SIRT-1 Pathway and the p75NTR/PI3K/Akt/MAPK Cascade in Neurological Disorders: Mechanistic Insights and Therapeutic Innovations

Neurological illnesses are debilitating diseases that affect brain function and balance. Due to their complicated aetiologies and progressive nature, neurodegenerative and neuropsychiatric illnesses are difficult to treat. These incurable conditions damage brain functions like mobility, cognition, and emotional regulation, but medication, gene therapy, and physical therapy can manage symptoms. Disruptions in cellular signalling pathways, especially those involving oxidative stress response, memory processing, and neurotransmitter modulation, contribute to these illnesses. This review stresses the interplay between key signalling pathways involved in neurological diseases, such as the Nrf2/Keap1/HO-1/SIRT-1 axis and the p75NTR/PI3K/Akt/MAPK cascade. To protect neurons from oxidative damage and death, the Nrf2 transcription factor promotes antioxidant enzyme production. The Keap1 protein releases Nrf2 during oxidative stress for nuclear translocation and gene activation. The review also discusses how neurotrophin signalling through the p75 neurotrophin receptor (p75NTR) determines cell destiny, whether pro-survival or apoptotic. The article highlights emerging treatment approaches targeting these signalling pathways by mapping these connections. Continued research into these molecular pathways may lead to new neurological disease treatments that restore cellular function and neuronal survival. In addition to enhanced delivery technologies, specific modulators and combination therapies should be developed to fine-tune signalling responses. Understanding these crosstalk dynamics is crucial to strengthening neurological illness treatment options and quality of life.

Herbal Interventions in Parkinson's Disease: A Systematic Review of Preclinical Studies

Parkinson's disease (PD) is the second most common neurodegenerative disorder, characterized by the progressive degeneration of dopaminergic neurons in the substantia nigra of the midbrain. With its incidence rising annually, the multi-mechanistic pathogenesis of PD presents new opportunities for the development of multi-target therapies. While previous studies have explored the therapeutic potential of natural products in PD, existing reviews often focus on single mechanisms or a limited number of compounds. While previous studies have explored the therapeutic potential of natural products in PD, existing reviews often focus on single mechanisms or a limited number of compounds. This article systematically evaluates preclinical studies published between 2018 and 2025, encompassing 32 bioactive components and 10 categories of traditional Chinese medicine (TCM) formulas. It highlights the therapeutic potential of TCM active ingredients for PD by examining key mechanisms, including oxidative stress, ferroptosis, neuroinflammation, gut microbiota imbalance, mitochondrial dysfunction, autophagy, and endoplasmic reticulum stress. By integrating these insights, this review provides an interdisciplinary perspective to guide the development of next-generation botanical drugs for PD.

Activating autophagy to eliminate toxic protein aggregates with small molecules in neurodegenerative diseases

Neurodegenerative diseases (NDs), such as Alzheimer disease, Parkinson disease, Huntington disease, amyotrophic lateral sclerosis, and frontotemporal dementia, are well known to pose formidable challenges for their treatment due to their intricate pathogenesis and substantial variability among patients, including differences in environmental exposures and genetic predispositions. One of the defining characteristics of NDs is widely reported to be the buildup of misfolded proteins. For example, Alzheimer disease is marked by amyloid beta and hyperphosphorylated Tau aggregates, whereas Parkinson disease exhibits α-synuclein aggregates. Amyotrophic lateral sclerosis and frontotemporal dementia exhibit TAR DNA-binding protein 43, superoxide dismutase 1, and fused-in sarcoma protein aggregates, and Huntington disease involves mutant huntingtin and polyglutamine aggregates. These misfolded proteins are the key biomarkers of NDs and also serve as potential therapeutic targets, as they can be addressed through autophagy, a process that removes excess cellular inclusions to maintain homeostasis. Various forms of autophagy, including macroautophagy, chaperone-mediated autophagy, and microautophagy, hold a promise in eliminating toxic proteins implicated in NDs. In this review, we focus on elucidating the regulatory connections between autophagy and toxic proteins in NDs, summarizing the cause of the aggregates, exploring their impact on autophagy mechanisms, and discussing how autophagy can regulate toxic protein aggregation. Moreover, we underscore the activation of autophagy as a potential therapeutic strategy across different NDs and small molecules capable of activating autophagy pathways, such as rapamycin targeting the mTOR pathway to clear α-synuclein and Sertraline targeting the AMPK/mTOR/RPS6KB1 pathway to clear Tau, to further illustrate their potential in NDs' therapeutic intervention. Together, these findings would provide new insights into current research trends and propose small-molecule drugs targeting autophagy as promising potential strategies for the future ND therapies. SIGNIFICANCE STATEMENT: This review provides an in-depth overview of the potential of activating autophagy to eliminate toxic protein aggregates in the treatment of neurodegenerative diseases. It also elucidates the fascinating interrelationships between toxic proteins and the process of autophagy of "chasing and escaping" phenomenon. Moreover, the review further discusses the progress utilizing small molecules to activate autophagy to improve the efficacy of therapies for neurodegenerative diseases by removing toxic protein aggregates.

Hydrogen sulfide improves depression-like behaviors in CUMS-induced mice by regulating autophagy

The pathogenesis of depression is associated with synaptic impairment and dysfunction in autophagy processes. Mendelian randomization (MR) analysis revealed that six GWAS IDs revealed a significant association between Beclin-1 levels and depression risk. Besides, all SNPs had a positive effect on depression risk. Analyzing neurons from depressed individuals using single-cell RNA sequencing (scRNA-seq) uncovered decreased expression of AKT, mTOR, and genes linked to synaptic plasticity. The activation of the PI3K/AKT/mTOR signaling has been demonstrated to control autophagy and have a protective effect on the nervous system. Hydrogen sulfide (H2S) is an endogenous gasotransmitter that can potentially treat various neurological disorders by improving neuronal synaptic plasticity. However, whether H2S regulates autophagy through PI3K/AKT/mTOR signaling, improves neuronal synaptic plasticity damage, and plays an antidepressant role is unclear. Our current research revealed that the reduction in the expression of p-PI3K, p-AKT, and p-mTOR proteins increase in neuronal autophagy activity and decline synaptic plasticity in mice with depression induced by chronic unpredictable mild stress (CUMS). Treatment with the exogenous hydrogen sulfide donor NaHS for one day and continuous treatment for one week improved the depression-like behaviors in the mice. Compared with those after one day of NaHS treatment, the above protein expression levels were restored and maintained, and the antidepressant effect was more significant after one week of continuous treatment with NaHS. Moreover, the PI3K inhibitor LY294002 was used to demonstrate that NaHS suppresses autophagy through activating the PI3K/AKT/mTOR signaling and ameliorates synaptic plasticity impairments. This study provides novel insights into the antidepressant mechanisms of H2S, highlighting its antidepressant therapeutic potential.

Association of TAB2 gene polymorphism with endometrial cancer susceptibility and clinical analysis

Objective

Transforming growth factor-β-activated kinase 1 binding protein 2 (TAB2) plays a vital role in inflammatory pathways. It has also been considered a potential target for the enhancement of the the antiestrogen effects. Previous evidence has indicated that TAB2 gene variants are associated with several diseases, whereas their potential correlation with endometrial cancer (EC) is unclear. This study aims to initially explore the association between TAB2 gene polymorphisms (rs237028 /AG, rs521845 T/G, and rs652921 T/C) and EC.

Materials and Methods

Polymerase chain reaction-restriction fragment length polymorphism was applied to determine the genotype composition and the allele frequencies of TAB2 gene variant polymorphisms in 270 EC patients and 294 healthy controls.

Results

The G allele of rs521845 was related to the increase of EC risk [p=0.08, odds ratio (OR): 0.72, 95% confidence interval (CI): 0.56-0.91]. Moreover, EC risk was associated with rs521845 in different genetic models (p=0.017, OR: 0.63, 95% CI: 0.44-0.91 in the codominant model; p=0.0051, OR: 0.61, 95% CI: 0.43-0.87 in the dominant model). For rs237028, the percentage of AG genotype in patients with highly differentiated tumours (G1) was significantly higher than that in moderately, poorly differentiated patients (G2/G3) (p=0.031, OR: 0.77, 95% CI: 0.45-1.30).

Conclusion

Our results showed that the rs521845 polymorphism of TAB2, was associated with EC risk, suggesting that TAB2 may play a crucial role in EC prognosis.

Identification of novel phenolic inhibitors from traditional Chinese medicine against toxic α-synuclein aggregation via regulating phase separation

Parkinson's disease (PD), a neurodegenerative disorder without cure, is characterized by the pathological aggregation of α-synuclein (α-Syn) in Lewy bodies. Classic deposition pathway and condensation pathway contribute to α-Syn aggregation, and liquid-liquid phase separation is the driving force for condensate formation, which subsequently undergo liquid-solid phase separation to form toxic fibrils. Traditional Chinese Medicine (TCM) has a long history in treating neurodegenerative disease; herein, we identified chemicals from herbs that inhibit α-Syn aggregation. We screened commonly prescribed TCMs for PD from the CNKI database and registered patents, 13 chemicals were identified in the TCMSP databases as candidate inhibitors, among which three phenols, forsythoside B (FTSB), echinacoside (ECH), and 4-hydroxyindole (C4-OH) efficiently inhibit α-Syn aggregation. Moreover, FTSB and ECH increase α-Syn fluidity within condensates, inhibit α-Syn transition into amyloid fibrils and reduce fibril-induced toxicity in SH-SY5Y cells. Importantly, they disaggregated preformed α-Syn amyloid fibrils. Notably, in an α-Syn overexpressing NL5901 C. elegans PD model, either FTSB or ECH treatment significantly extended the lifespan and improved the PD-like movement disorders, both in the preventive and therapeutic treatment approaches, by reducing toxic α-Syn inclusion formation and improving the fluidity of α-Syn. Together, we offer new therapeutic candidates targeting phase separation-associated aggregation for PD.

Exploring the therapeutic potential of Chinese herbs on comorbid type 2 diabetes mellitus and Parkinson's disease: A mechanistic study

ETHNOPHARMACOLOGICAL RELEVANCE

Type 2 diabetes mellitus (T2DM) and Parkinson's disease (PD) are chronic conditions that affect the aging population, with increasing prevalence globally. The rising prevalence of comorbidity between these conditions, driven by demographic shifts, severely impacts the quality of life of patients, posing a significant burden on healthcare resources. Chinese herbal medicine has been used to treat T2DM and PD for millennia. Pharmacological studies have demonstrated that medicinal herbs effectively lower blood glucose levels and exert neuroprotective effects, suggesting their potential as adjunctive therapy for concurrent management of T2DM and PD.

AIM OF THE STUDY

To elucidate the shared mechanisms underlying T2DM and PD, particularly focusing on the potential mechanisms by which medicinal herbs (including herbal formulas, single herbs, and active compounds) may treat these diseases, to provide valuable insights for developing therapeutics targeting comorbid T2DM and PD.

MATERIALS AND METHODS

Studies exploring the mechanisms underlying T2DM and PD, as well as the treatment of these conditions with medicinal herbs, were extracted from several electronic databases, including PubMed, Web of Science, Google Scholar, and China National Knowledge Infrastructure (CNKI).

RESULTS

Numerous studies have shown that inflammation, oxidative stress, insulin resistance, impaired autophagy, gut microbiota dysbiosis, and ferroptosis are shared mechanisms underlying T2DM and PD mediated through the NLRP3 inflammasome, NF-κB, MAPK, Keap1/Nrf2/ARE, PI3K/AKT, AMPK/SIRT1, and System XC--GSH-GPX4 signaling pathways. Thirty-four medicinal herbs, including 2 herbal formulas, 4 single herbs, and 28 active compounds, have been reported to potentially exert anti-T2DM and anti-PD effects by targeting these shared mechanisms.

CONCLUSIONS

Traditional Chinese medicine effectively combats T2DM and PD through shared pathological mechanisms, highlighting their potential for application in treating these comorbid conditions.

A Review of the Protective Effects of Alkaloids against Alpha-synuclein Toxicity in Parkinson's Disease

BACKGROUND

Alpha-synuclein (α-syn) aggregation products may cause neural injury and several neurodegenerative disorders (NDs) known as α-synucleinopathies. Alkaloids are secondary metabolites present in a variety of plant species and may positively affect human health, particularly α-synucleinopathy-associated NDs.

AIM

To summarize the latest scientific data on the inhibitory properties of alkaloids in α- synucleinopathies, especially in Parkinson's disease.

METHODS

Literature search was performed using web-based databases including Web of Science, PubMed, and Scopus up to January 2024, in the English language.

RESULTS

Harmala alkaloids, caffein, lycorine, piperin, acetylcorynoline, berberin, papaverine, squalamine, trodusquemine and nicotin have been found to be the most active natural alkaloids against synucleinopathy. The underlying mechanisms that contribute to this effect would be the inhibition of α-syn aggregation; elimination of formed aggregates; improvement in autophagy activation; promotion of the activity and expression of antioxidative enzymes; and prevention of oxidative injury and apoptosis in dopaminergic neurons.

CONCLUSION

The findings of the present study highlight the inhibitory activities of alkaloids against synucleinopathy. However, no clinical data supports the reported activities in humans, which calls attention to the need for conducting clinical trials to elucidate the efficacy, safety, proper dosage, unwanted effects and pharmacokinetics aspects of alkaloids in humans.

MST1, a novel therapeutic target for Alzheimer's disease, regulates mitochondrial homeostasis by mediating mitochondrial DNA transcription and the PI3K-Akt-ROS pathway

BACKGROUND

Alzheimer's disease (AD) is a prevalent irreversible neurodegenerative condition marked by gradual cognitive deterioration and neuronal loss. The mammalian Ste20-like kinase (MST1)-Hippo pathway is pivotal in regulating cell apoptosis, immune response, mitochondrial function, and oxidative stress. However, the association between MST1 and mitochondrial function in AD remains unknown. Therefore, this study investigates the effect of MST1 on neuronal damage and cognitive impairment by regulating mitochondrial homeostasis in AD.

METHODS

In this study, 4- and 7-month-old 5xFAD mice were selected to simulate the early and middle stages of AD, respectively; age-matched wild-type mice served as controls for comparative analysis. Adeno-associated virus (AAV) was injected into the hippocampus of mice. Four weeks post-injection, cognitive function, neuronal damage indicators, and mitochondrial morphology, dynamics, oxidative stress, ATP, and apoptosis-related indicators were evaluated. Additionally, RNA-sequencing was performed on the hippocampal tissue of 5xFAD mice and MST1-knockdown 5xFAD mice. Subsequently, Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed on differentially expressed genes to elucidate the potential mechanism of MST1. In vitro studies were performed to investigate the effects of MST1 on SH-SY5Y model cell viability and mitochondrial function and validate the potential underlying molecular mechanisms.

RESULTS

MST1 overexpression accelerated neuronal degeneration and cognitive deficits in vivo while promoting oxidative stress and mitochondrial damage. Similarly, in vitro, MST1 overexpression facilitated apoptosis and mitochondrial dysfunction. MST1 knockdown and chemical inactivation reduced cognitive decline, mitochondrial dysfunction, and neuronal degeneration. Mechanistically, MST1 regulated the transcription of mitochondrial genes, including MT-ND4L, MT-ATP6, and MT-CO2, by binding to PGC1α. Moreover, MST1 influenced cellular oxidative stress through the PI3K-Akt-ROS pathway, ultimately disrupting mitochondrial homeostasis and mediating cell damage.

CONCLUSIONS

Cumulatively, these results suggest that MST1 primarily regulates mitochondrial DNA transcription levels by interacting with PGC1α and modulates cellular oxidative stress through the PI3K-Akt-ROS pathway, disrupting mitochondrial homeostasis. This discovery can be exploited to potentially enhance mitochondrial energy metabolism pathways by targeting MST1, offering novel potential therapeutic targets for treating AD.

Monocrotaline-mediated autophagy via inhibiting PI3K/AKT/mTOR pathway induces apoptosis in rat hepatocytes

Monocrotaline (MCT), a major pyrrolizidine alkaloid, is well-known for its high liver toxicity. Dysregulation of autophagy induced apoptosis can lead to various liver diseases, including those induced by chemical compounds. Therefore, we aim to explore whether autophagy might serve as a potential strategy for addressing liver apoptosis caused by MCT. In primary rat hepatocytes (PRHs), MCT significantly increased the number of autophagosomes and the expression levels of LC3II, Becline-1, and Atg5, while it decreased the expression of p62 in a concentration-dependent manner at doses of 100, 200, 300, and 400 μM. Western blot assays revealed MCT inhibited the phosphorylation levels of the PI3K/AKT/mTOR pathway. To elucidate the role of autophagy in mediating MCT-induced apoptosis, we further pretreated PRHs with the autophagy agonist Rapamycin and the inhibitors Bafilomycin A1 and Chloroquine, respectively, and assessed the apoptosis of PRHs induced by MCT. The results displayed that Rapamycin increased the apoptosis rate and the expression of cleaved caspase-3, whereas Bafilomycin A1 and Chloroquine reduced the apoptosis and the expression of cleaved caspase-3 in PRHs. This study confirms that autophagy enhances PRHs apoptosis induced by MCT. In summary, this study demonstrates that MCT-induced autophagy via inhibition of the PI3K/AKT/mTOR pathway can lead to apoptosis in PRHs.

Multiple effects of spicy flavors on neurological diseases through the intervention of TRPV1: a critical review

The spicy properties of foods are contributed by various spicy flavor substances (SFs) such as capsaicin, piperine, and allicin. Beyond their distinctive sensory characteristics, SFs also influence health conditions and numerous studies have associated spicy flavors with disease treatment. In this review, we enumerate different types of SFs and describe their role in food processing, with a specific emphasis on critically examining their influence on human wellness. Particularly, detailed insights into the mechanisms through which SFs enhance physiological balance and alleviate neurological diseases are provided, and a systematic analysis of the significance of transient receptor potential vanilloid type-1 (TRPV1) in regulating metabolism and nervous system homeostasis is presented. Moreover, enhancing the accessibility and utilization of SFs can potentially amplify the physiological effects. This review aims to provide compelling evidence for the integration of food flavor and human health.

Dose-Dependent Alterations of Lysosomal Activity and Alpha-Synuclein in Peripheral Blood Monocyte-Derived Macrophages and SH-SY5Y Neuroblastoma Cell Line by upon Inhibition of MTOR Protein Kinase - Assessment of the Prospects of Parkinson's Disease Therapy

To date, the molecular mechanisms of the common neurodegenerative disorder Parkinson's disease (PD) are unknown and, as a result, there is no neuroprotective therapy that may stop or slow down the process of neuronal cell death. The aim of the current study was to evaluate the prospects of using the mTOR molecule as a potential target for PD therapy due to the dose-dependent effect of mTOR kinase activity inhibition on cellular parameters associated with, PD pathogenesis. The study used peripheral blood monocyte-derived macrophages and SH-SY5Y neuroblastoma cell line. As a result, we have for the first time showed that inhibition of mTOR by Torin1 only at a concentration of 100 nM affects the level of the lysosomal enzyme glucocerebrosidase (GCase), encoded by the GBA1 gene. Mutations in GBA1 are considered a high-risk factor for PD development. This concentration led a decrease in pathological phosphorylated alpha-synuclein (Ser129), an increase in its stable tetrameric form with no changes in the lysosomal enzyme activities and concentrations of lysosphingolipids. Our findings suggest that inhibition of the mTOR protein kinase could be a promising approach for developing therapies for PD, particularly for GBA1-associated PD.

Amide Alkaloids as Privileged Sources of Senomodulators for Therapeutic Purposes in Age-Related Diseases

Nature is an important source of bioactive compounds and has continuously made a large contribution to the discovery of new drug leads. Particularly, plant-derived compounds have long been identified as highly interesting in the field of aging research and senescence. Many plants contain bioactive compounds that have the potential to influence cellular processes and provide health benefits. Among them, Piper alkaloids have emerged as interesting candidates in the context of age-related diseases and particularly senescence. These compounds have been shown to display a variety of features, including antioxidant, anti-inflammatory, neuroprotective, and other bioactive properties that may help counteracting the effects of cellular aging processes. In the review, we will put the emphasis on piperlongumine and other related derivatives, which belong to the Piper alkaloids, and whose senomodulating potential has emerged during the last several years. We will also provide a survey on their potential in therapeutic perspectives of age-related diseases.