Alpha-Lipoic Acid Mediates Clearance of Iron Accumulation by Regulating Iron Metabolism in a Parkinson's Disease Model Induced by 6-OHDA

Buddlejasaponin IVb ameliorates ferroptosis of dopaminergic neuron by suppressing IRP2-mediated iron overload in Parkinson's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Parkinson's disease (PD) is the second neurodegenerative disease that lacks effective treatments. Buddlejasaponin IVb (BJP-IVb) is the main bioactive component of herbs in genus Clinopodium which display antioxidative, anti-inflammatory and neuroprotective activities. However, the role of BJP-IVb in PD still remains unknown.

AIM OF THE STUDY

This study aimed to evaluate the effect of BJP-IVb on dopaminergic neurodegeneration in PD and clarified the underlying mechanisms from the aspect of iron overload-mediated ferroptosis.

MATERIALS AND METHODS

One-methyl-4-phenylpyridinium (MPP+) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD models were established in this study. Behavioral tests, cell cytotoxicity assay, tyrosine hydroxylase (TH) and Nissl staining were performed to evaluate the antiparkinsonian effect of BJP-IVb. Cellular ultrastructure, iron content and lipid peroxidation were detected to evaluate iron overload-mediated dopaminergic neuron ferroptosis. Iron regulatory protein 2 (IRP2) and iron transport-related proteins were detected by immunofluorescence and Western blot to evaluated iron transport. Finally, plasmid vector-mediated IRP2 overexpression were performed to further clarify the molecular mechanism.

RESULTS

BJP-IVb alleviated MPP+-induced neurotoxicity in vitro and improved MPTP-induced dopaminergic neuron loss and motor dysfunctions of PD mice, confirming an effect of BJP-IVb against dopaminergic neurodegeneration of PD. Further results revealed that BJP-IVb protected against PD by suppressing iron overload-mediated dopaminergic neuron ferroptosis, as evidenced by the attenuated lipid peroxidation, decreased iron content and changes in cellular ultrastructure. Finally, the decreased iron regulatory protein (IRP2) was confirmed to be responsible for BJP-IVb-mediated ferroptosis suppression by modulating iron transport-related proteins and alleviating iron overload.

CONCLUSION

BJP-IVb suppressed iron overload-mediated dopaminergic neuron ferroptosis and improved motor dysfunctions in PD, which was achieved by inhibiting IRP2-mediated iron overload. This study provided a potential drug candidate for the treatment of PD.

Visualization of ferroptosis in brain diseases and ferroptosis-inducing nanomedicine for glioma

A remarkable body of new data establishes that many degenerative brain diseases and some acute injury situations in the brain may be associated with ferroptosis. In recent years, ferroptosis has also attracted great interest in the cancer research community, partly because it is a unique mode of cell death distinct from other forms and thus has great therapeutic potential for brain cancer. Glioblastoma is a highly aggressive and fatal human cancer, accounting for 60% of all primary brain tumors. Despite the development of various pharmacological and surgical modalities, the survival rates of high-grade gliomas have remained poor over the past few decades. Recent evidence has revealed that ferroptosis is involved in tumor initiation, progression, and metastasis, and manipulating ferroptosis could offer a novel strategy for glioma management. Nanoparticles have been exploited as multifunctional platforms that can cross the blood-brain barrier and deliver therapeutic agents to the brain to address the pressing need for accurate visualization of ferroptosis and glioma treatment. To create efficient and durable ferroptosis inducers, many researchers have engineered nanocomposites to induce a more effective ferroptosis for therapy. In this review, we present the mechanism of ferroptosis and outline the current strategies of imaging and nanotherapy of ferroptosis in brain diseases, especially glioma. We aim to provide up-to-date information on ferroptosis and emphasize the potential clinical implications of ferroptosis for glioma diagnosis and treatment. However, regulation of ferroptosis in vivo remains challenging due to a lack of compounds.

Dyshomeostasis of Iron and Its Transporter Proteins in Cypermethrin-Induced Parkinson's Disease

The etiology of Parkinson's disease (PD) is highly complex and is still indefinable. However, a number of studies have indicated the involvement of pesticides and transition metals. Copper, magnesium, iron, and zinc have emerged as important metal contributors. Exposure to pesticides causes an accumulation of transition metals in the substantia nigra (SN) region of the brain. The cypermethrin model of PD is characterized by mitochondrial dysfunction, autophagy impairment, oxidative stress, etc. However, the effect of cypermethrin on metal homeostasis is not yet explored. The study was designed to delineate the role of metals and their transporter proteins in cypermethrin-induced animal and cellular models of PD. The level of copper, magnesium, iron, and zinc was checked in the nigrostriatal tissue and serum by atomic absorption spectroscopy. Since cypermethrin consistently increased iron content in the nigrostriatal tissue and serum after 12 weeks of exposure, the level of iron transporter proteins, such as divalent metal transporter-1 (DMT-1), ceruloplasmin, transferrin, ferroportin, and hepcidin, and their in silico interaction with cypermethrin were checked. 3,3'-Diaminobenzidine-enhanced Perl's staining showed an elevated number of iron-positive cells in the SN of cypermethrin-treated rats. Molecular docking studies revealed a strong binding affinity between cypermethrin and iron transporter protein receptors of humans and rats. Furthermore, cypermethrin increased the expression of DMT-1 and hepcidin while reducing the expression of transferrin, ceruloplasmin, and ferroportin in the nigrostriatal tissue and human neuroblastoma cells. These observations suggest that cypermethrin alters the expression of iron transporter proteins leading to iron dyshomeostasis, which could contribute to dopaminergic neurotoxicity.

Mitochondria and Brain Disease: A Comprehensive Review of Pathological Mechanisms and Therapeutic Opportunities

Mitochondria play a vital role in maintaining cellular energy homeostasis, regulating apoptosis, and controlling redox signaling. Dysfunction of mitochondria has been implicated in the pathogenesis of various brain diseases, including neurodegenerative disorders, stroke, and psychiatric illnesses. This review paper provides a comprehensive overview of the intricate relationship between mitochondria and brain disease, focusing on the underlying pathological mechanisms and exploring potential therapeutic opportunities. The review covers key topics such as mitochondrial DNA mutations, impaired oxidative phosphorylation, mitochondrial dynamics, calcium dysregulation, and reactive oxygen species generation in the context of brain disease. Additionally, it discusses emerging strategies targeting mitochondrial dysfunction, including mitochondrial protective agents, metabolic modulators, and gene therapy approaches. By critically analysing the existing literature and recent advancements, this review aims to enhance our understanding of the multifaceted role of mitochondria in brain disease and shed light on novel therapeutic interventions.

Brain-wide transcriptome-based metabolic alterations in Parkinson's disease: human inter-region and human-experimental model correlations

Alterations in brain metabolism are closely associated with the molecular hallmarks of Parkinson's disease (PD). A clear understanding of the main metabolic perturbations in PD is therefore important. Here, we retrospectively analysed the expression of metabolic genes from 34 PD-control post-mortem human brain transcriptome data comparisons from literature, spanning multiple brain regions. We found high metabolic correlations between the Substantia nigra (SN)- and cerebral cortex-derived tissues. Moreover, three clusters of PD patient cohorts were identified based on perturbed metabolic processes in the SN - each characterised by perturbations in (a) bile acid metabolism (b) omega-3 fatty acid metabolism, and (c) lipoic acid and androgen metabolism - metabolic themes not comprehensively addressed in PD. These perturbations were supported by concurrence between transcriptome and proteome changes in the expression patterns for CBR1, ECI2, BDH2, CYP27A1, ALDH1B1, ALDH9A1, ADH5, ALDH7A1, L1CAM, and PLXNB3 genes, providing a valuable resource for drug targeting and diagnosis. Also, we analysed 58 PD-control transcriptome data comparisons from in vivo/in vitro disease models and identified experimental PD models with significant correlations to matched human brain regions. Collectively, our findings suggest metabolic alterations in several brain regions, heterogeneity in metabolic alterations between study cohorts for the SN tissues and the need to optimize current experimental models to advance research on metabolic aspects of PD.

Alpha lipoic acid ameliorates motor deficits by inhibiting ferroptosis in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disease. Ferroptosis shares several features with PD pathophysiology, and anti-ferroptosis molecules are neuroprotective in PD animal models. As an antioxidant and iron chelating agent, alpha lipoic acid (ALA) has a neuroprotective effect on PD; however, the influence of ALA on ferroptosis in PD remains unclear. This study aimed to determine the mechanism of ALA in regulating ferroptosis in PD models. Results showed that ALA could ameliorate motor deficits in PD models and regulate iron metabolism by upregulating ferroportin (FPN) and ferritin heavy chain 1 (FTH1) and downregulating iron importer divalent metal transporter 1 (DMT1). Moreover, ALA decreased the accumulation of reactive oxygen species (ROS) and lipid peroxidation, rescued mitochondrial damage, and prevented ferroptosis effectively by inhibiting the downregulation of glutathione peroxidase 4 (GPX4) and cysteine/glutamate transporter (xCT) in PD. Mechanistic study indicated that the activation of SIRT1/NRF2 pathway was involved in the upregulation effect of GPX4 and FTH1. Thus, ALA ameliorates motor deficits in PD models by regulating iron metabolism and mitigating ferroptosis through the SIRT1/NRF2 signaling pathway.

Neuroprotective effects of morroniside from Cornus officinalis sieb. Et zucc against Parkinson's disease via inhibiting oxidative stress and ferroptosis

Parkinson's disease (PD) is the second most common neurodegenera-tive disorder after Alzheimer disease accompanied by the death of dopaminergic neurons and brain nigrostriatal mitochondrial damage in the elderly population. The features of the disease include tremor, rigidity, postural instability, and motor retardation. The pathogenesis of Parkinson's disease is complex, and abnormal lipid metabolism resulting in ferroptosis due to the excessive accumulation of free radicals from oxidative stress in the substantia nigra of the brain was thought to be one of the factors causing the disease. Morroniside has been reported to have significant neuroprotective effects, although it has not been studied in PD. Therefore, this study focused on determining the neuroprotective effects of morroniside (25, 50, and 100 mg/kg) on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 30 mg/kg)-induced mice models of PD and explored 1-methyl-4-phenylpyridinium MPP+-induced ferroptosis in PC12 cells. Morroniside restored impaired motor function in the PD mice models while reducing neuronal injury. The activation of nuclear factor erythroid 2-related factor 2/antioxidant response elements (Nrf2/ARE) by morroniside promoted antioxidation, the content of reducing agent glutathione (GSH) increased, and the level of the lipid metabolite malondialdehyde (MDA) decreased. Notably, morroniside inhibited ferroptosis in substantia nigra of the brain and PC12 cells, reduced iron levels, and upregulated the expression of the iron-regulated proteins glutathione peroxidase 4 (GPX4), solute carrier family 7 member 11 (SLC7A11), ferritin heavy chain 1 (FTH-1), and ferroportin (FPN). More importantly, morroniside repaired the mitochondrial damage, restored the mitochondrial respiratory chain, and inhibited the production of reactive oxygen species (ROS). These data indicated that morroniside could activate the Nrf2/ARE signaling pathway to increase the antioxidant capacity, thereby inhibiting abnormal lipid metabolism and protecting dopaminergic neurons from ferroptosis in PD.

Neuroprotective Efficacy of a Nanomicellar Complex of Carnosine and Lipoic Acid in a Rat Model of Rotenone-Induced Parkinson's Disease

Oxidative stress, accompanied by mitochondrial dysfunction, is a key mechanism involved in the pathogenesis of Parkinson's disease (PD). Both carnosine and lipoic acid are potent antioxidants, the applicability of which in therapy is hindered by their limited bioavailability. This study aimed to evaluate the neuroprotective properties of a nanomicellar complex of carnosine and lipoic acid (CLA) in a rotenone-induced rat model of PD. Parkinsonism was induced via the administration of 2 mg/kg rotenone over the course of 18 days. Two doses of intraperitoneal CLA (25 mg/kg and 50 mg/kg) were administered alongside rotenone to assess its neuroprotective effect. At 25 mg/kg CLA decreased muscle rigidity and partially restored locomotor activity in animals that received rotenone. Furthermore, it caused an overall increase in brain tissue antioxidant activity, accompanied by a 19% increase in neuron density in the substantia nigra and increased dopamine levels in the striatum relative to animals that only received rotenone. Based on the acquired results, it may be concluded that CLA have neuroprotective properties and could potentially be beneficial in PD treatment when used in conjunction with the base therapy.

Alpha-lipoic acid activates AMPK to protect against oxidative stress and apoptosis in rats with diabetic peripheral neuropathy

PURPOSE

To investigate the AMPK pathway-mediated effect of alpha-lipoic acid (ALA) on the dorsal root ganglia (DRGs) of rats with diabetic peripheral neuropathy (DPN) and to attempt to elucidate the underlying mechanism.

METHODS

Sprague-Dawley rats (n = 15) were randomly divided into three groups. The control group was fed a standard diet, and the other groups were fed a high-carbohydrate/high-fat diet. Diabetes was established by a single streptozotocin (STZ) (30 mg/kg) injection, and control rats were injected with an equal volume of citrate buffer. ALA (60 mg/kg/day) was administered for 12 weeks. The nerve conduction velocity (NCV) of the sciatic nerve was measured. Glutathione (GSH) and malondialdehyde (MDA) concentrations in serum were measured with the thiobarbituric acid method and biochemistry. Pathological changes in the rat DRGs were observed. AMPK, phospho-AMPK (p-AMPK), nuclear factor erythroid-2-related factor 2 (Nrf2), phospho-nuclear factor erythroid-2-related factor 2 (p-Nrf2), heme oxygenase 1 (HO-1), quinone oxidoreductase 1 (NQO1), Forkhead box O3 (FoxO3a), phospho-Forkhead box O3 (p-FoxO3a), and Bcl-2 interacting mediator of cell death (Bim) expression levels were assessed by immunohistochemistry and western blotting.

RESULTS

ALA improved the motor NCV (MNCV) and sensory NCV (SNCV) of rats with DPN and reduced their mechanical pain threshold. ALA increased serum GSH concentrations and decreased serum MDA concentrations. Additionally, AMPK was activated by ALA. Nrf2, p-Nrf2, HO-1, and NQO1 expression was upregulated, while FoxO3a, p-FoxO3a, and Bim expression was downregulated. ALA reduced oxidative stress and apoptosis in DRG.

CONCLUSION

ALA alleviates DPN and improves peripheral nerve function. ALA reduces oxidative stress by activating Nrf2 through AMPK and inhibits FoxO3a and Bim thereby reducing neuronal apoptosis.

Baicalein Attenuates Brain Iron Accumulation through Protecting Aconitase 1 from Oxidative Stress in Rotenone-Induced Parkinson's Disease in Rats

Aconitase 1 (ACO1) links oxidative stress and iron accumulation in Parkinson's disease (PD). ACO1 loses its aconitase activity and turns into iron regulatory protein 1 (IRP1) upon oxidative stress. IRP1 plays an important role in the accumulation of intracellular iron. Baicalein is a flavonoid isolated from the roots of Scutellaria baicalensis. The present results show that baicalein could bind to ACO1 and protect its isoform from the oxidative stress induced by reactive oxygen species (ROS) and reactive nitrogen species (RNS). Furthermore, baicalein promoted aconitase activity and inhibited IRP1 activation in rotenone-induced PD models. Additionally, baicalein decreased the hydroxyl radicals generated by iron. In conclusion, baicalein attenuated iron accumulation and iron-induced oxidative stress in the brain of PD rats by protecting ACO1.

Mitochondrial Dysfunction and Neurodegenerative Disorders: Role of Nutritional Supplementation

Mitochondrial dysfunction has been implicated in the pathogenesis of a number of neurodegenerative disorders, including Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis, multisystem atrophy, and progressive supranuclear palsy. This article is concerned specifically with mitochondrial dysfunction as defined by reduced capacity for ATP production, the role of depleted levels of key nutritionally related metabolites, and the potential benefit of supplementation with specific nutrients of relevance to normal mitochondrial function in the above neurodegenerative disorders. The article provides a rationale for a combination of CoQ10, B-vitamins/NADH, L-carnitine, vitamin D, and alpha-lipoic acid for the treatment of the above neurodegenerative disorders.

The Molecular Mechanisms of Ferroptosis and Its Role in Blood-Brain Barrier Dysfunction

The blood-brain barrier (BBB) is a selective, semi-permeable layer of endothelial cells that protects the central nervous system from harmful substances circulating in blood. It is one of the important barriers of the nervous system. BBB dysfunction is an early pathophysiological change observed in nervous system diseases. There are few treatments for BBB dysfunction, so this motivates the review. Ferroptosis is a novel cell death mode caused by iron-mediated lipid peroxidation accumulation, which has recently attracted more attention due to its possible role in nervous system disorders. Studies have shown that lipid peroxidation and iron accumulation are related to the barrier dysfunction, especially the expression of tight junction proteins. Therefore, examination of the relationship between ferroptosis and BBB dysfunction may reveal new targets for the treatment of brain diseases.

Exploring the Causal Effect of Constipation on Parkinson’s Disease Through Mediation Analysis of Microbial Data

Background and Aims

Parkinson’s disease (PD) is a worldwide neurodegenerative disease with an increasing global burden, while constipation is an important risk factor for PD. The gastrointestinal tract had been proposed as the origin of PD in Braak’s gut–brain axis hypothesis, and there is increasing evidence indicating that intestinal microbial alteration has a role in the pathogenesis of PD. In this study, we aim to investigate the role of intestinal microbial alteration in the mechanism of constipation-related PD.

Methods

We adapted our data from Hill‐Burns et al., in which 324 participants were enrolled in the study. The 16S rRNA gene sequence data were processed, aligned, and categorized using DADA2. Mediation analysis was used to test and quantify the extent by which the intestinal microbial alteration explains the causal effect of constipation on PD incidence.

Results

We found 18 bacterial genera and 7 species significantly different between groups of constipated and non-constipated subjects. Among these bacteria, nine genera and four species had a significant mediation effect between constipation and PD. All of them were short-chain fatty acid (SCFA)-producing bacteria that were substantially related to PD. Results from the mediation analysis showed that up to 76.56% of the effect of constipation on PD was mediated through intestinal microbial alteration.

Conclusion

Our findings support that gut dysbiosis plays a critical role in the pathogenesis of constipation-related PD, mostly through the decreasing of SCFA-producing bacteria, indicating that probiotics with SCFA-producing bacteria may be promising in the prevention and treatment of constipation-related PD.

Limitations

1) Several potential confounders that should be adjusted were not provided in the original dataset. 2) Our study was conducted based on the assumption of constipation being the etiology of PD; however, constipation and PD may mutually affect each other. 3) Further studies are necessary to explain the remaining 23.44% effect leading to PD by constipation.

Role of Iron Chelation and Protease Inhibition of Natural Products on COVID-19 Infection

Although the epidemic caused by SARS-CoV-2 callings for international attention to develop new effective therapeutics, no specific protocol is yet available, leaving patients to rely on general and supportive therapies. A range of respiratory diseases, including pulmonary fibrosis, have been associated with higher iron levels that may promote the course of viral infection. Recent studies have demonstrated that some natural components could act as the first barrier against viral injury by affecting iron metabolism. Moreover, a few recent studies have proposed the combination of protease inhibitors for therapeutic use against SARS-CoV-2 infection, highlighting the role of viral protease in virus infectivity. In this regard, this review focuses on the analysis, through literature and docking studies, of a number of natural products able to counteract SARS-CoV-2 infection, acting both as iron chelators and protease inhibitors.

Oxidopamine and oxidative stress: Recent advances in experimental physiology and pharmacology

Oxidopamine (6-hydroxydopamine, 6-OHDA) is a toxin commonly used for the creation of experimental animal models of Parkinson's disease, attention-deficit hyperactivity disorder, and Lesch-Nyhan syndrome. Its exact mechanism of action is not completely understood, although there are many indications that it is related to the generation of reactive oxygen species (ROS), primarily in dopaminergic neurons. In certain experimental conditions, oxidopamine may also cause programmed cell death via various signaling pathways. Oxidopamine may also have a significant impact on chromatin structure and nuclear structural organization in some cells. Today, many researchers use oxidopamine-associated oxidative damage to evaluate different antioxidant-based pharmacologically active compounds as drug candidates for various neurological and non-neurological diseases. Additional research is needed to clarify the exact biochemical pathways associated with oxidopamine toxicity, related ROS generation and apoptosis. In this short review, we focus on the recent research in experimental physiology and pharmacology, related to the cellular and animal experimental models of oxidopamine - mediated toxicity.