Neuroprotective effects of cordycepin on MPTP-induced Parkinson's disease mice via suppressing PI3K/AKT/mTOR and MAPK-mediated neuroinflammation.

Parkinson's disease (PD) is a prevalent progressive and multifactorial neurodegenerative disorder. Cordycepin is known to exhibit antitumor, anti-inflammatory, antioxidative stress, and neuroprotective effects; however, few studies have explored the neuroprotective mechanism of cordycepin in PD. Using a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model, we investigated the impact of cordycepin on PD and its underlying molecular mechanisms. The findings indicated that cordycepin significantly mitigated MPTP-induced behavior disorder and neuroapoptosis, diminished the loss of dopaminergic neurons in the striatum-substantia nigra pathway, elevated striatal monoamine levels and its metabolites, and inhibited the polarization of microglia and the expression of pro-inflammatory factors. Subsequent proteomic and phosphoproteomic analyses revealed the involvement of the MAPK, mTOR, and PI3K/AKT signaling pathways in the protective mechanism of cordycepin. Cordycepin treatment inhibited the activation of the PI3K/AKT/mTOR signaling pathway and enhanced the expression of autophagy proteins in the striatum and substantia nigra. We also demonstrated the in vivo inhibition of the ERK/JNK signaling pathway by cordycepin treatment. In summary, our investigation reveals that cordycepin exerts neuroprotective effects against PD by promoting autophagy and suppressing neuroinflammation and neuronal apoptosis by inhibiting the PI3K/AKT/mTOR and ERK/JNK signaling pathways. This finding highlights the favorable characteristics of cordycepin in neuroprotection and provides novel molecular insights into the neuroprotective role of natural products in PD.

Folic Acid Rescues Dopaminergic Neurons in MPTP-Induced Mice by Inhibiting the NLRP3 Inflammasome and Ameliorating Mitochondrial Impairment.

Parkinson's disease (PD) is marked by the degeneration of dopaminergic neurons of the substantia nigra (SN), with neuroinflammation and mitochondrial dysfunction being key contributors. The neuroprotective potential of folic acid (FA) in the dopaminergic system of PD was assessed in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model. MPTP (20 mg/kg of body weight) was administered to C57BL/6J mice to simulate PD symptoms followed by FA treatment (5 mg/kg of body weight). Behavioral tests, pole, rotarod, and open-field tests, evaluated motor function, while immunohistochemistry, ELISA, RT-qPCR, and Western blotting quantified neuroinflammation, oxidative stress markers, and mitochondrial function. FA supplementation considerably improved motor performance, reduced homocysteine levels and mitigated oxidative damage in the SN. The FA-attenuated activation of the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome lessened glial cell activity and reduced neuroinflammation. At the molecular level, FA reduced DNA damage, downregulated phosphorylated p53, and induced the expression of peroxisome proliferator-activated receptor α coactivator 1α (PGC-1α), enhancing mitochondrial function. Therefore, FA exerts neuroprotection in MPTP-induced PD by inhibiting neuroinflammation via NLRP3 inflammasome suppression and promoting mitochondrial integrity through the p53-PGC-1α pathway. Notable limitations of our study include its reliance on a single animal model and the incompletely elucidated mechanisms underlying the impact of FA on mitochondrial dynamics. Future investigations will explore the clinical utility of FA and its molecular mechanisms, further advancing it as a potential therapeutic for managing and delaying the progression of PD.

Orally administered neohesperidin attenuates MPTP-induced neurodegeneration by inhibiting inflammatory responses and regulating intestinal flora in mice.

Parkinson's disease (PD), a neurodegenerative disease, is the leading cause of movement disorders. Neuroinflammation plays a critical role in PD pathogenesis. Neohesperidin (Neo), a natural flavonoid extracted from citric fruits exhibits anti-inflammatory effects. However, the effect of Neo on PD progression is unclear. This study aimed to investigate the effects of Neo on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD in mice and its underlying mechanism. Our results indicated that Neo administration ameliorated motor impairment and neural damage in MPTP-injected mice, by inhibiting neuroinflammation and regulating gut microbial imbalance. Additionally, Neo administration reduced colonic inflammation and tissue damage. Mechanistic studies revealed that Neo suppressed the MPTP-induced inflammatory response by inhibiting excessive activation of NF-κB and MAPK pathways. In summary, the present study demonstrated that Neo administration attenuates neurodegeneration in MPTP-injected mice by inhibiting inflammatory responses and regulating the gut microbial composition. This study may provide the scientific basis for the use of Neo in the treatment of PD and other related diseases.

Creatine supplementation with exercise reduces α-synuclein oligomerization and necroptosis in Parkinson's disease mouse model.

Parkinson's disease (PD) is an incurable neurological disorder that causes typical motor deficits. In this study, we investigated the effects of creatine supplementation and exercise in the subacute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. We found that 2% creatine supplementation and/or exercise intervention for 4 weeks elicited neurobehavioral recovery and neuroprotective effects regarding dopaminergic cell loss in MPTP-treated mice; this effect implies functional preservation of dopaminergic cells in the substantia nigra, as reflected by tyrosine hydroxylase expression recovery. Creatine and exercise reduced necroptotic activity in dopaminergic cells by lowering mixed lineage kinase domain-like protein (MLKL) modification to active phenotypes (phosphorylation at Ser345 and oligomerization) and phosphorylated receptor-interacting protein kinase 1 (RIPK1) (Ser166-p) and RIPK3 (Ser232-p) levels. In addition, creatine and exercise reduced the MPTP-induced increase in pathogenic α-synuclein forms, such as Ser129 phosphorylation and oligomerization. Furthermore, creatine and exercise had anti-inflammatory and antioxidative effects in MPTP mice, as evidenced by a decrease in microglia activation, NF-κB-dependent pro-inflammatory molecule expression, and increase in antioxidant enzyme expression. These phenotypic changes were associated with the exercise/creatine-induced AMP-activated protein kinase (AMPK)/nuclear factor erythroid 2-related factor 2 (Nrf2) and sirtuin 3 (SIRT3)/forkhead box O3 (FoxO3a) signaling pathways. In all experiments, combining creatine with exercise resulted in considerable improvement over either treatment alone. Consequently, these findings suggest that creatine supplementation with exercise has anti-inflammatory, antioxidative, and anti-α-synucleinopathy effects, thereby reducing necroptotic cell death in a PD mouse model.

The Involvement of Progranulin for α-Synuclein Reduction through Autolysosome Formation.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor symptoms and neuropathological features, such as loss of dopaminergic neurons in the substantia nigra pars compacta and accumulation of alpha-synuclein (α-Syn). Progranulin (PGRN) is a secreted growth factor that exhibits anti-inflammatory properties and regulates lysosomal function. Although autophagy-lysosome pathway is the main degradative pathway for α-Syn, the molecular mechanistic relationship between PD and PGRN remains unclear. In this study, we investigated the role of PGRN in PD pathology. PGRN protein expression in striatum was increased in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model mice. Intracerebroventricular (i.c.v.) administration of PGRN ameliorated the decrease in expression of tyrosine hydroxylase, a dopaminergic neuron marker, in MPTP-treated mice. Furthermore, i.c.v. administration of PGRN ameliorated 6-hydroxydopamine-induced motor deficits. In SH-SY5Y human neuroblastoma cells, 1-methyl-4-phenylpyridinium ion (MPP+), an active metabolite of MPTP, increased α-Syn expression. In contrast, PGRN ameliorated MPP+-induced increase in α-Syn expression. Although PGRN decreased the levels of autophagy-related proteins Sequestosome-1 (p62) and MAP1LC3 (LC3)-II, PGRN did not influence the phosphorylation of AMP-activated protein kinase and mechanistic target of rapamycin, which are also proteins that regulate autophagy. Immunostaining analysis showed that PGRN ameliorated MPP+-induced increase of LC3 puncta, indicator of autophagosome, and co-localization of LC3 and α-Syn. The DALGreen assay showed that PGRN ameliorated MPP+-induced decreasing trend of autolysosomes. These results suggest that PGRN participates in α-Syn degradation via acceleration of the autophagy-lysosome pathway and is a potential therapeutic target for PD.

A Low-Protein, High-Carbohydrate Diet Exerts a Neuroprotective Effect on Mice with 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine-Induced Parkinson's Disease by Regulating the Microbiota-Metabolite-Brain Axis and Fibroblast Growth Factor 21.

Parkinson's disease (PD) is closely linked to lifestyle factors, particularly dietary patterns, which have attracted interest as potential disease-modifying factors. Eating a low-protein, high-carbohydrate (LPHC) diet is a promising dietary intervention against brain aging; however, its protective effect on PD remains elusive. Here, we found that an LPHC diet ameliorated 1-methyl-4-phenyl-1,2,3,6-tetrathydropyridine (MPTP)-induced motor deficits, decreased dopaminergic neuronal death, and increased the levels of striatal dopamine, serotonin, and their metabolites in PD mice. Levels of fibroblast growth factor 21 (FGF-21), a member of the fibroblast growth factor family, were elevated in PD mice following LPHC treatment. Furthermore, the administration of FGF-21 exerted a protective effect on MPTP-induced PC12 cells, similar to the effect of an LPHC diet in MPTP-induced mice. Sequencing of the 16S rDNA from fecal microbiota revealed that an LPHC diet normalized the gut bacterial composition imbalance in PD mice, as evidenced by the increased abundance of the genera Bifidobacterium, Ileibacterium, Turicibacter, and Blautia and decreased abundance of Bilophila, Alistipes, and Bacteroides. PICRUSt-predicted fecal microbiome function revealed that an LPHC diet suppressed lipopolysaccharide biosynthesis and the citrate cycle (TCA cycle), biosynthesis of ubiquinone and other terpenoid-quinones, and oxidative phosphorylation pathways caused by MPTP, and enhanced the biosynthesis of amino acids, carbohydrate metabolism, and biosynthesis of other secondary metabolites. A nonmetabolomic analysis of the serum and feces showed that an LPHC diet significantly increased the levels of aromatic amino acids (AAAs), including tryptophan, tyrosine, and phenylalanine. In addition, an LPHC diet elevated the serum concentrations of bile acids (BAs), particularly tauroursodeoxycholic acid (TUDCA) and taurine. Collectively, our current findings point to the potential mechanism of administering an LPHC diet in attenuating movement impairments in MPTP-induced PD mice, with AAAs, microbial metabolites (TUDCA and taurine), and FGF-21 as key mediators along the gut-microbiota-brain axis.

Vitamin E Analog Trolox Attenuates MPTP-Induced Parkinson's Disease in Mice, Mitigating Oxidative Stress, Neuroinflammation, and Motor Impairment.

Trolox is a potent antioxidant and a water-soluble analog of vitamin E. It has been used in scientific studies to examine oxidative stress and its impact on biological systems. Trolox has been shown to have a neuroprotective effect against ischemia and IL-1ß-mediated neurodegeneration. In this study, we investigated the potential protective mechanisms of Trolox against a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease mouse model. Western blotting, immunofluorescence staining, and ROS/LPO assays were performed to investigate the role of trolox against neuroinflammation, the oxidative stress mediated by MPTP in the Parkinson's disease (PD) mouse model (wild-type mice (C57BL/6N), eight weeks old, average body weight 25-30 g). Our study showed that MPTP increased the expression of α-synuclein, decreased tyrosine hydroxylase (TH) and dopamine transporter (DAT) levels in the striatum and substantia nigra pars compacta (SNpc), and impaired motor function. However, Trolox treatment significantly reversed these PD-like pathologies. Furthermore, Trolox treatment reduced oxidative stress by increasing the expression of nuclear factor erythroid-2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1). Lastly, Trolox treatment inhibited the activated astrocytes (GFAP) and microglia (Iba-1), also reducing phosphorylated nuclear factor-κB, (p-NF-κB) and tumor necrosis factor-alpha (TNF-α) in the PD mouse brain. Overall, our study demonstrated that Trolox may exert neuroprotection on dopaminergic neurons against MPTP-induced oxidative stress, neuroinflammation, motor dysfunction, and neurodegeneration.

The molecular mechanism of three novel peptides from C-phycocyanin alleviates MPTP-induced Parkinson's disease-like pathology in zebrafish.

Previous studies have shown that peptides isolated from C-phycocyanin (C-PC) possess various functions including antioxidant and anticancer activities. However, there is little research on C-PC peptides applied for the neuroprotective effect against a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease (PD) model. In this study, twelve novel peptides from C-PC were isolated, purified and identified, and the anti-PD effect of the synthesized peptides was evaluated in a zebrafish PD model. As a result, three of these peptides (MAAAHR, MPQPPAK, and MTAAAR) significantly reversed the loss of dopamine neurons and cerebral vessels, and reduced the locomotor impairment in PD zebrafish. In addition, three novel peptides could inhibit the MPTP-induced decrease of antioxidant enzymes (SOD, CAT, and GSH-Px) and increase the ROS and protein carbonylation content. In addition, they can also alleviate apoptosis of brain regions and acetylcholinesterase (AChE) activity in zebrafish. Further studies elucidated the potential molecular mechanism of peptides' anti-PD effects in the larvae. The results showed that C-PC peptides could modulate multiple genes associated with oxidative stress, autophagy and apoptosis signaling pathways, and thereby alleviate the occurrence of PD symptoms. Overall, our results highlight the neuroprotective effects of three novel peptides and provide valuable mechanistic insights and a promising drug target for the treatment of PD.

Experimental models of chemically induced Parkinson's disease in zebrafish at the embryonic larval stage: a systematic review.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra that results in a decrease in dopamine levels, resulting in motor-type disturbances. Different vertebrate models, such as rodents and fish, have been used to study PD. In recent decades, Danio rerio (zebrafish) has emerged as a potential model for the investigation of neurodegenerative diseases due to its homology to the nervous system of humans. In this context, this systematic review aimed to identify publications that reported the utilization of neurotoxins as an experimental model of parkinsonism in zebrafish embryos and larvae. Ultimately, 56 articles were identified by searching three databases (PubMed, Web of Science, and Google Scholar). Seventeen studies using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 4 1-methyl-4-phenylpyridinium (MPP+), 24 6-hydroxydopamine (6-OHDA), 6 paraquat/diquat, 2 rotenone, and 6 articles using other types of unusual neurotoxins to induce PD were selected. Neurobehavioral function, such as motor activity, dopaminergic neuron markers, oxidative stress biomarkers, and other relevant parameters in the zebrafish embryo-larval model were examined. In summary, this review provides information to help researchers determine which chemical model is suitable to study experimental parkinsonism, according to the effects induced by neurotoxins in zebrafish embryos and larvae.

Investigating Therapeutic Effects of Indole Derivatives Targeting Inflammation and Oxidative Stress in Neurotoxin-Induced Cell and Mouse Models of Parkinson's Disease.

Neuroinflammation and oxidative stress have been emerging as important pathways contributing to Parkinson's disease (PD) pathogenesis. In PD brains, the activated microglia release inflammatory factors such as interleukin (IL)-ß, IL-6, tumor necrosis factor (TNF)-α, and nitric oxide (NO), which increase oxidative stress and mediate neurodegeneration. Using 1-methyl-4-phenylpyridinium (MPP+)-activated human microglial HMC3 cells and the sub-chronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD, we found the potential of indole derivative NC009-1 against neuroinflammation, oxidative stress, and neurodegeneration for PD. In vitro, NC009-1 alleviated MPP+-induced cytotoxicity, reduced NO, IL-1ß, IL-6, and TNF-α production, and suppressed NLR family pyrin domain containing 3 (NLRP3) inflammasome activation in MPP+-activated HMC3 cells. In vivo, NC009-1 ameliorated motor deficits and non-motor depression, increased dopamine and dopamine transporter levels in the striatum, and reduced oxidative stress as well as microglia and astrocyte reactivity in the ventral midbrain of MPTP-treated mice. These protective effects were achieved by down-regulating NLRP3, CASP1, iNOS, IL-1ß, IL-6, and TNF-α, and up-regulating SOD2, NRF2, and NQO1. These results strengthen the involvement of neuroinflammation and oxidative stress in PD pathogenic mechanism, and indicate NC009-1 as a potential drug candidate for PD treatment.

Sophora alopecuroides Alleviates Neuroinflammation and Oxidative Damage of Parkinson's Disease In Vitro and In Vivo.

For centuries, Sophora alopecuroides L. has been used both as a food and an herbal medicine in northern China. A new cytisine-type alkaloid, N-methylene-(5,7,4[Formula: see text]-trihydroxy)-isoflavone (LY01), was found in the fruits of Sophora alopecuroides L. and shows neuroprotective effects against Parkinson's disease (PD). PD is a frequently occurring, irreversible neurodegenerative disease that seriously threatens the health of the elderly population. There is no cure for PD. The available treatments help manage the symptoms, but their use is limited by multiple side effects. Therefore, more pharmacological treatments addressing this pathology are urgently required. This study aimed to evaluate the neuroprotective effects of LY01 against PD, as well as their underlying mechanisms, using both in vitro and in vivo experimental models. A 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine hydrochloride (MPTP)-induced mouse model of PD was used to assess the effects of LY01 on the motor coordination deficit, progression of the pathology, and molecular characteristics. 1-Methyl-4-phenylpyridinium (MPP[Formula: see text])-activated SH-SY5Y cells and lipopolysaccharide (LPS)-activated BV-2 cells were used to evaluate LY01 effects on oxidative damage and neuroinflammation. In the rotarod test, LY01 alleviated the impaired motor coordination in PD mice. Furthermore, LY01 treatment prevented the loss of dopaminergic neurons in the substantia nigra and striatum of the PD mice, reduced neuroinflammation in the mice with MPTP-induced PD and the LPS-activated BV-2 cells, and diminished oxidative stress in the PD mice and the MPP[Formula: see text]-induced SH-SY5Y cells. In conclusion, these results suggest the potential of LY01 as a therapeutic agent for treating PD.

Transcriptomic and metabolomic analyses provide insights into the attenuation of neuroinflammation by nervonic acid in MPTP-stimulated PD model mice.

Nervonic acid is one of the most promising bioactive fatty acids, which is believed to be beneficial for the recovery of human cognitive disorders. However, the detailed neuroprotective effects and mode of action of nervonic acid have not yet been fully elucidated. In this study, we used an MPTP-stimulated mouse Parkinson's disease (PD) model as a target to investigate the neuroprotective effects by behavioral tests and integrative analysis of trancriptomes and metabolomes of PD mouse brain with nervonic acid injections. The KEGG pathway enrichment analysis of transcriptomes showed that the genes involved in neuroinflammation were significantly increased after MPTP induction and have been greatly inhibited by nervonic acid injection, while nervonic acid also greatly improved nerve growth and synaptic plasticity pathways which were significantly downregulated by MPTP. At the same time, the upregulation of oleic acid and arachidonic acid metabolism pathways and the downregulation of amino acid metabolism pathways in metabolomes were particularly highlighted in the nervonic acid protection groups compared with the PD model. Meanwhile, it was found that arachidonic acid, oleic acid and taurine play an important regulatory role in the neuroprotective mechanism of nervonic acid through fatty acid metabolism by integrative analysis. Therefore, our study laid a solid foundation for further studies on the specific role of nervonic acid in the inhibition of PD at the level of metabolic regulation.

Gastric Enteric Glial Cells: A New Contributor to the Synucleinopathies in the MPTP-Induced Parkinsonism Mouse.

Accumulating evidence has shown that Parkinson's disease (PD) is a systemic disease other than a mere central nervous system (CNS) disorder. One of the most important peripheral symptoms is gastrointestinal dysfunction. The enteric nervous system (ENS) is regarded as an essential gateway to the environment. The discovery of the prion-like behavior of α-synuclein makes it possible for the neurodegenerative process to start in the ENS and spread via the gut-brain axis to the CNS. We first confirmed that synucleinopathies existed in the stomachs of chronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)/probenecid (MPTP/p)-induced PD mice, as indicated by the significant increase in abnormal aggregated and nitrated α-synuclein in the TH-positive neurons and enteric glial cells (EGCs) of the gastric myenteric plexus. Next, we attempted to clarify the mechanisms in single MPTP-injected mice. The stomach naturally possesses high monoamine oxidase-B (MAO-B) activity and low superoxide dismutase (SOD) activity, making the stomach susceptible to MPTP-induced oxidative stress, as indicated by the significant increase in reactive oxygen species (ROS) in the stomach and elevated 4-hydroxynonenal (4-HNE) in the EGCs after MPTP exposure for 3 h. Additionally, stomach synucleinopathies appear before those of the nigrostriatal system, as determined by Western blotting 12 h after MPTP injection. Notably, nitrated α-synuclein was considerably increased in the EGCs after 3 h and 12 h of MPTP exposure. Taken together, our work demonstrated that the EGCs could be new contributors to synucleinopathies in the stomach. The early-initiated synucleinopathies might further influence neighboring neurons in the myenteric plexus and the CNS. Our results offer a new experimental clue for interpreting the etiology of PD.

Neuroprotective Effects of Bifidobacterium breve CCFM1067 in MPTP-Induced Mouse Models of Parkinson's Disease.

There is mounting evidence that the microbiota-gut-brain axis (MGBA) is critical in the pathogenesis and progression of Parkinson's disease (PD), suggesting that probiotic therapy restoring gut microecology may slow down disease progression. In this study, we examined the disease-alleviating effects of Bifidobacterium breve CCFM1067, orally administered for 5 weeks in a PD mouse model. Our study shows that supplementation with the probiotic B. breve CCFM1067 protected dopaminergic neurons and suppressed glial cell hyperactivation and neuroinflammation in PD mice. In addition, the antioxidant capacity of the central nervous system was enhanced and oxidative stress was alleviated. Moreover, B. breve CCFM1067 protected the blood-brain and intestinal barriers from damage in the MPTP-induced mouse model. The results of fecal microbiota analysis showed that B. breve CCFM1067 intervention could act on the MPTP-induced microecological imbalance in the intestinal microbiota, suppressing the number of pathogenic bacteria (Escherichia-Shigella) while increasing the number of beneficial bacteria (Bifidobacterium and Akkermansia) in PD mice. In addition, the increase in short chain fatty acids (acetic and butyric acids) may explain the anti-inflammatory action of B. breve CCFM1067 in the gut or brain of the MPTP-induced PD mouse model. In conclusion, we demonstrated that the probiotic B. breve CCFM1067, which can prevent or treat PD by modulating the gut-brain axis, can be utilized as a possible new oral supplement for PD therapy.

Neurotrophic Role of the Next-Generation Probiotic Strain L. lactis MG1363-pMG36e-GLP-1 on Parkinson's Disease via Inhibiting Ferroptosis.

Parkinson's disease (PD) is a neurodegenerative disease (NDD) with high and ongoing morbidity, bringing heavy burdens to PD patients seriously. Finding neurotrophic drugs still remains vital due to the limited drug spectrum available currently. Substantial evidence suggests that glucagon-like peptide 1 (GLP-1) exerts neuroprotection on PD, yet the short-lived biological activity markedly hindered its application. Herein, we investigated the neurotrophic role of the next-generation probiotic strain L. lactis MG1363-pMG36e-GLP-1 in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mice and elucidated the mechanisms. Our data suggested that L. lactis MG1363-pMG36e-GLP-1 markedly enhanced motor deficits induced by MPTP via rescuing dopaminergic (DAergic) neurodegeneration in substantia nigra (SN). We found that L. lactis MG1363-pMG36e-GLP-1 exerts neurotrophic effects via activating the Keap1/Nrf2/GPX4 signalling pathway to down-regulate ACSL4 and up-regulate FSP1 to suppress ferroptosis. Additionally, the decreased oxidative stress levels via suppressing generations of ROS and MDA supported our findings. Lastly, we identified that the L. lactis MG1363-pMG36e-GLP-1 administration reversed dysbiosis in PD mice by increasing Akkermansia, Oscillospira, and Sutterella at the genus level. These results indicated that the neurotrophic effects of the next-generation probiotics L. lactis MG1363-pMG36e-GLP-1 against MPTP-induced Parkinsonism are mediated by modulating oxidative stress, inhibiting ferroptosis, and redressing dysbiosis.

AV-101, a Pro-Drug Antagonist at the NMDA Receptor Glycine Site, Reduces L-Dopa Induced Dyskinesias in MPTP Monkeys.

N-methyl-D-aspartate (NMDA) receptors have been implicated in L-Dopa-induced dyskinesias (LID) in Parkinson's disease patients, but the use of antagonists that directly inhibit this receptor is associated with severe side effects. L-4-chlorokynurenine (4-Cl-KYN or AV-101) is a pro-drug of 7-chlorokynurenic acid (7-Cl-KYNA), a potent and specific antagonist of the glycine (GlyB) co-agonist site of NMDA receptors. The 7-Cl-KYNA has limited ability to cross the blood-brain barrier, whereas AV-101 readily accesses the brain. We investigated if AV-101 reduces LID in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned monkeys while maintaining the antiparkinsonian activity of L-Dopa. A first pilot study using three dyskinetic MPTP monkeys showed that acute AV-101 treatment (250 and 450 mg/kg) reduced LID and maintained the antiparkinsonian activity of L-Dopa. The main study using six additional dyskinetic MPTP monkeys showed that repeated AV-101 treatment (250 mg/kg, b.i.d. for 4 consecutive days) maintained their L-Dopa antiparkinsonian response. We measured significantly less LID when AV-101 was combined with L-Dopa treatment. AV-101 alone or with L-Dopa had no non-motor adverse effects in MPTP monkeys. Our study showed antidyskinetic activity of AV-101 in MPTP monkeys was comparable to amantadine tested previously in our laboratory in this model. We observed no adverse effects with AV-101, which is an improvement over amantadine, with its known side effects.

Isoalantolactone (IAL) Regulates Neuro-Inflammation and Neuronal Apoptosis to Curb Pathology of Parkinson's Disease.

Parkinson's disease (PD) is a neurodegenerative disease in which neuronal apoptosis and associated inflammation are involved in its pathogenesis. However, there is still no specific treatment that can stop PD progression. Isoalantolactone (IAL) plays a role in many inflammation-related diseases. However, its effect and mechanism in PD remain unclear. In this study, results showed that IAL administration ameliorated 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced PD-related pathological impairment and decreased motor activity in mice. Results from in vitro mechanistic studies showed that IAL regulated apoptosis-related proteins by activating the AKT/Nrf2 pathway, thereby suppressing the apoptosis of SN4741 cells induced by N-methyl-4-phenylpyridinium Iodide (MPP+). On the other hand, IAL inhibited LPS-induced release of pro-inflammatory mediators in BV2 cells by activating the AKT/Nrf2/HO-1 pathway and inhibiting the NF-κB pathway. In addition, IAL protected SN4741 from microglial activation-mediated neurotoxicity. Taken together, these results highlight the beneficial role of IAL as a novel therapy and potential PD drug due to its pharmacological profile.

Anti-Inflammatory and Neuroprotective Effects of Morin in an MPTP-Induced Parkinson's Disease Model.

Neurodegenerative diseases such as Parkinson's disease (PD) are known to be related to oxidative stress and neuroinflammation, and thus, modulating neuroinflammation offers a possible means of treating PD-associated pathologies. Morin (2',3,4',5,7-pentahydroxy flavone) is a flavonol with anti-oxidative and anti-inflammatory effects found in wines, herbs, and fruits. The present study was undertaken to determine whether a morin-containing diet has protective effects in an MPTP-induced mouse model of PD. Mice were fed a control or morin diet for 34 days, and then MPTP (30 mg/kg, i.p.) was administered daily for 5 days to induce a PD-like pathology. We found that dietary morin prevented MPTP-induced motor dysfunction and ameliorated dopaminergic neuronal damage in striatum (STR) and substantia nigra (SN) in our mouse model. Furthermore, MPTP-induced neuroinflammation was significantly reduced in mice fed morin. In vitro studies showed that morin effectively suppressed glial activations in primary microglia and astrocytes, and biochemical analysis and a docking simulation indicated that the anti-inflammatory effects of morin were mediated by blocking the extracellular signal-regulated kinase (ERK)-p65 pathway. These findings suggest that morin effectively inhibits glial activations and has potential use as a functional food ingredient with therapeutic potential for the treatment of PD and other neurodegenerative diseases associated with neuroinflammation.

Defining Specific Cell States of MPTP-Induced Parkinson's Disease by Single-Nucleus RNA Sequencing.

Parkinson's disease (PD) is a neurodegenerative disease with an impairment of movement execution that is related to age and genetic and environmental factors. 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a neurotoxin widely used to induce PD models, but the effect of MPTP on the cells and genes of PD has not been fully elucidated. By single-nucleus RNA sequencing, we uncovered the PD-specific cells and revealed the changes in their cellular states, including astrocytosis and endothelial cells' absence, as well as a cluster of medium spiny neuron cells unique to PD. Furthermore, trajectory analysis of astrocyte and endothelial cell populations predicted candidate target gene sets that might be associated with PD. Notably, the detailed regulatory roles of astrocyte-specific transcription factors Dbx2 and Sox13 in PD were revealed in our work. Finally, we characterized the cell-cell communications of PD-specific cells and found that the overall communication strength was enhanced in PD compared with a matched control, especially the signaling pathways of NRXN and NEGR. Our work provides an overview of the changes in cellular states of the MPTP-induced mouse brain.

COVID-19 Infection Enhances Susceptibility to Oxidative Stress-Induced Parkinsonism.

BACKGROUND: Viral induction of neurological syndromes has been a concern since parkinsonian-like features were observed in patients diagnosed with encephalitis lethargica subsequent to the 1918 influenza pandemic. Given the similarities in the systemic responses after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection with those observed after pandemic influenza, there is a question whether a similar syndrome of postencephalic parkinsonism could follow coronavirus disease 2019 infection. OBJECTIVE: The goal of this study was to determine whether prior infection with SARS-CoV-2 increased sensitivity to a mitochondrial toxin known to induce parkinsonism. METHODS: K18-hACE2 mice were infected with SARS-CoV-2 to induce mild-to-moderate disease. After 38 days of recovery, mice were administered a non-lesion-inducing dose of the parkinsonian toxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and euthanized 7 days later. Subsequent neuroinflammation and substantia nigra pars compacta (SNpc) dopaminergic (DA) neuron loss were determined and compared with SARS-CoV-2 or MPTP alone. RESULTS: K18-hACE2 mice infected with SARS-CoV-2 or MPTP showed no SNpc DA neuron loss after MPTP. In mice infected and recovered from SARS-CoV-2 infection, MPTP induced a 23% or 19% greater loss of SNpc DA neurons than SARS-CoV-2 or MPTP, respectively (P < 0.05). Examination of microglial activation showed a significant increase in the number of activated microglia in both the SNpc and striatum of the SARS-CoV-2 + MPTP group compared with SARS-CoV-2 or MPTP alone. CONCLUSIONS: Our observations have important implications for long-term public health, given the number of people who have survived SARS-CoV-2 infection, as well as for future public policy regarding infection mitigation. However, it will be critical to determine whether other agents known to increase risk for PD also have synergistic effects with SARS-CoV-2 and are abrogated by vaccination. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.