MPTP-induced Parkinson's Disease Model Research Articles

Tim-3 Deficiency Ameliorates Motor Deficits and Neuroinflammation in MPP+/MPTP-Induced Parkinson's Disease Models via the NF-κB/NLRP3 Pathway.

Parkinson's disease (PD) is a common neurodegenerative disorder, and neuroinflammation plays a pivotal role in its pathogenesis. T-cell immunoglobulin and mucin-domain-containing molecule 3 (Tim-3) is a crucial immunoregulatory mediator in various diseases; however, its roles and underlying molecular mechanisms in PD remain unclear. We established in vitro and in vivo 1-methyl-4-phenylpyridinium (MPP+)/1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD models in Tim-3-knockout BV2 cells and mice, respectively. Motor function was assessed through behavioral tests, including pole, traction, forced swimming, and open field tests. Immunofluorescence was used to examine dopaminergic neuron loss and glial activation. The expression levels of nuclear factor-kappa B (NF-κB)/nucleotide-binding oligomerization domain-like receptor 3 (NLRP3) pathway components were evaluated by western blotting. Proinflammatory cytokines were measured via enzyme-linked immunosorbent assay (ELISA). Compared with the wild-type, Tim-3 expression was significantly increased in the PD model, and Tim-3 deficiency mitigated MPTP-induced motor deficits, dopaminergic neuron loss, and glial cell activation. Furthermore, Tim-3 deficiency suppressed neuroinflammation by negatively modulating the NF-κB/NLRP3 pathway, thereby downregulating the expression of the proinflammatory cytokines IL-1β, IL-18, IL-6, and TNF-α. These findings indicate that Tim-3 plays a proinflammatory role in PD by regulating the NF-κB/NLRP3 pathway, highlighting Tim-3 as a promising therapeutic target for PD.

Lactiplantibacillus plantarum SG5 inhibits neuroinflammation in MPTP-induced PD mice through GLP-1/PGC-1α pathway

Mounting evidence suggests that alterations in gut microbial composition play an active role in the pathogenesis of Parkinson's disease (PD). Probiotics are believed to modulate gut microbiota, potentially influencing PD development through the microbiota-gut-brain axis. However, the potential beneficial effects of Lactiplantibacillus plantarum SG5 (formerly known as Lactobacillus plantarum, abbreviated as L. plantarum) on PD and its underlying mechanisms remain unclear. In this study, we employed immunofluorescence, Western blotting, ELISA, and 16S rRNA gene sequencing to investigate the neuroprotective effects of L. plantarum SG5 against neuroinflammation in an MPTP-induced PD model and to explore the underlying mechanisms. Our results demonstrated that L. plantarum SG5 ameliorated MPTP-induced motor deficits, dopaminergic neuron loss, and elevated α-synuclein protein levels. Furthermore, SG5 inhibited MPTP-triggered overactivation of microglia and astrocytes in the substantia nigra (SN), attenuated disruption of both blood-brain and intestinal barriers, and suppressed the release of inflammatory factors in the colon and SN. Notably, SG5 modulated the composition and structure of the gut microbiota in mice. The MPTP-induced decrease in colonic GLP-1 secretion was reversed by SG5 treatment, accompanied by increased expression of GLP-1R and PGC-1α in the SN. Importantly, the GLP-1R antagonist Exendin 9–39 and PGC-1α inhibitor SR18292 attenuated the protective effects of SG5 in PD mice. In conclusion, we demonstrate a neuroprotective role of L. plantarum SG5 in the MPTP-induced PD mouse model, which likely involves modulation of the gut microbiota and, significantly, the GLP-1/PGC-1α signaling pathway.

Shisandra Decoction Alleviates Parkinson's Disease Symptoms in a Mouse Model Through PI3K/AKT/mTOR Signalling Pathway.

The present study aimed to characterize neuroprotective effects of Schisandra Decoction (Sch D) treatment in a mouse model of Parkinson's disease (PD), and to explore underlying mechanisms focused on the mammalian target of rapamycin (mTOR) signaling pathway. 50 male C57 BL/6 mice were randomly assigned to either control (n = 10) or 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model (n = 40) groups. PD mice were further divided into four groups of ten mice each: MPTP group, LY294002 group, Sch D group, and LY2940002 + Sch D group. Mice from each group were assessed in pole climbing, rotary rod and open field tests. Brain Tyrosine hydroxylase (TH) protein was observed using immunohistochemistry. mRNA levels of PTEN, PI3K and LC3 in brain tissue were measured using RT-PCR. Protein levels of PTEN, PI3K, Akt, p-Akt, mTOR, p-mTOR, p70s6K, p62, LC3II / I, α-synuclein (α-syn), TH in brain tissue were assessed by Western blotting (WB). In behavioral tests, PD mice treated with Sch D showed reduced pole climbing time, longer rotarod duration, and greater distance traveled. In terms of neuroprotection, PD mice in the Sch D group exhibited higher levels of TH protein and enhanced α-syn clearance. Regarding autophagy, compared to the control group, mice in the MPTP group had elevated PTEN protein expression, which inhibited PI3K, p-AKT/AKT, and p-mTOR/mTOR protein levels, decreased LC3II/I protein expression, and increased P62 protein expression. Treatment with Sch D reversed these effects. Sch D reduces α-syn aggregation in the brains of MPTP-induced PD model mice, exerts neuroprotective effects, and improves motor function. Additionally, Sch D inhibits autophagy through the PI3K/AKT/mTOR pathway. The neuroprotective effect of Sch D may involve the suppression of abnormal autophagy and its antioxidant properties, which indirectly reduces α-syn accumulation. Future studies should assess the impact of Sch D on oxidative stress markers to evaluate its antioxidant effects.

Key Lipoprotein Receptor Targeted Echinacoside-Liposomes Effective Against Parkinson's Disease in Mice Model.

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by the degeneration of dopaminergic neurons in the substantia nigra. The precise molecular mechanisms underlying neuronal loss in PD remain unknown, and there are currently no effective treatments for PD-associated neurodegeneration. Echinacoside (ECH) is known for its neuroprotective effects, which include scavenging cellular reactive oxygen species and promoting mitochondrial fusion. However, the blood-brain barrier (BBB) limits the bioavailability of ECH in the brain, posing a significant challenge to its use in PD treatment. We synthesized and characterized PEGylated ECH liposomes (ECH@Lip) and peptide angiopep-2 (ANG) modified liposomes (ECH@ANG-Lip). The density of ANG in ANG-Lip was optimized using bEnd.3 cells. The brain-targeting ability of the liposomes was assessed in vitro using a transwell BBB model and in vivo using an imaging system and LC-MS. We evaluated the enhanced neuroprotective properties of this formulation in a the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model. The ECH@ANG-Lip demonstrated significantly higher whole-brain uptake compared to ECH@Lip and free ECH. Furthermore, ECH@ANG-Lip was more effective in mitigating MPTP-induced behavioral impairment, oxidative stress, dopamine depletion, and dopaminergic neuron death than both ECH@Lip and free ECH. The formulation used in our study significantly enhanced the neuroprotective efficacy of ECH in the MPTP-induced PD model. Thus, ECH@ANG-Lip shows considerable potential for improving the bioavailability of ECH and providing neuroprotective effects in the brain.

TMEM106B Knockdown Exhibits a Neuroprotective Effect in Parkinson's Disease via Decreasing Inflammation and Iron Deposition.

Parkinson's disease (PD) is closely related to iron accumulation and inflammation. Emerging evidence indicates that TMEM106B plays an essential role in PD. But whether TMEM106B could act on neuroinflammation and iron metabolism in PD has not yet been investigated. The aim of this study was to investigate the pathological mechanisms of inflammation and iron metabolism of TMEM106B in PD. 1-methyl-4-phenylpyridinium (MPP+)- and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced SH-SY5Y cells and mice were treated with LV-shTMEM106B and AAV-shTMEM106B to construct PD cellular and mouse models. Pole tests and open-field test (OFT) were performed to evaluate the locomotion of the mice. Immunohistochemistry and iron staining were used to detect TH expression and iron deposition in the SN. Iron staining was used to measure the levels of iron. Western blotting was used to detect the expression of inflammatory factors (tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6)), NOD-like receptor protein 3 (NLRP3) inflammasome, divalent metal transporter 1 (DMT1), and Ferroportin1 (FPN1)). Knockdown of TMEM106B improved motor ability and rescued dopaminergic (DA) neuron loss. TMEM106B knockdown attenuated the increases of TNF-α, IL-6, NLRP3 inflammasome, and DMT1 expression in the MPP+ and MPTP-induced PD models. Furthermore, TMEM106B knockdown also increases the expression of FPN1. This study provides the first evidence that knockdown of TMEM106B prevents dopaminergic neurodegeneration by modulating neuroinflammation and iron metabolism.

The Aggregation of α-Synuclein in the Dorsomedial Striatum Significantly Impairs Cognitive Flexibility in Parkinson's Disease Mice.

This study focused on α-synuclein (α-syn) aggregation in the dorsomedial striatum (DMS) so as to investigate its role in the cognitive flexibility of Parkinson's disease (PD). Here, we investigated the cognitive flexibility by assessing reversal learning abilities in MPTP-induced subacute PD model mice and in C57BL/6J mice with α-syn aggregation in the DMS induced by adenovirus (AAV-SNCA) injection, followed by an analysis of the target protein's expression and distribution. PD mice exhibited impairments in reversal learning, positively correlated with the expression of phosphorylated α-syn in the DMS. Furthermore, the mice in the AAV-SNCA group exhibited reversal learning deficits and a reduction in acetylcholine levels, accompanied by protein alterations within the DMS. Notably, the administration of a muscarinic receptor 1 (M1R) agonist was able to alleviate the aforementioned phenomenon. These findings suggest that the impaired cognitive flexibility in PD may be attributed to the diminished activation of acetylcholine to M1R caused by α-syn aggregation.

Optimization of the Preparation Process of Glucuronomannan Oligosaccharides and Their Effects on the Gut Microbiota in MPTP-Induced PD Model Mice.

Parkinson's disease (PD) is a prevalent neurodegenerative disorder, and accumulating evidence suggests a link between dysbiosis of the gut microbiota and the onset and progression of PD. In our previous investigations, we discovered that intraperitoneal administration of glucuronomannan oligosaccharides (GMn) derived from Saccharina japonica exhibited neuroprotective effects in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model. However, the complicated preparation process, difficulties in isolation, and remarkably low yield have constrained further exploration of GMn. In this study, we optimized the degradation conditions in the preparation process of GMn through orthogonal experiments. Subsequently, an MPTP-induced PD model was established, followed by oral administration of GMn. Through a stepwise optimization, we successfully increased the yield of GMn, separated from crude fucoidan, from 1~2/10,000 to 4~8/1000 and indicated the effects on the amelioration of MPTP-induced motor deficits, preservation of dopamine neurons, and elevation in striatal neurotransmitter levels. Importantly, GMn mitigated gut microbiota dysbiosis induced by MPTP in mice. In particular, GM2 significantly reduced the levels of Akkermansia, Verrucomicrobiota, and Lactobacillus, while promoting the abundance of Roseburia and Prevotella compared to the model group. These findings suggest that GM2 can potentially suppress PD by modulating the gut microbiota, providing a foundation for the development of a novel and effective anti-PD marine drug.

LRRK2 regulates ferroptosis through the system Xc-GSH-GPX4 pathway in the neuroinflammatory mechanism of Parkinson's disease.

Parkinson's disease (PD) is the most prevalent neurodegenerative disorder. Neuroinflammation mediated by activated microglia and apoptosis of dopaminergic (DA) neurons in the midbrain are its primary pathological manifestations. Leucine-rich repeat protein kinase 2 (LRRK2) kinase has been observed to increase expression during neuroinflammation,however, the effect of LRRK2 on microglia activation remains poorly understood. In this study, we have established lipopolysaccharide (LPS) treated BV2 cells and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) models for both in vivo and in vitro investigation. Our data in vivo reveal that LRRK2 can promote microglia activation by regulating ferroptosis and activatingnuclear factor-κB. Inhibition of LRRK2 expression effectively suppressed the LPS-induced pro-inflammatory cytokines and facilitated the secretion of neuroprotective factors. Importantly, by co-overexpressing LRRK2 and glutathione peroxidase 4 (GPX4), we identified the system Xc-GSH-GPX4 pathway as a crucial component in LRRK2-mediated microglial ferroptosis and inflammatory responses. Using a microglial culture supernatant (MCS) transfer model, we found that inhibiting LRRK2 or downregulating ferroptosis in BV2 cells prevented SH-SY5Y cell apoptosis. Additionally, we observed abundant expression of LRRK2 and P-P65 in the midbrain, which was elevated in the MPTP-induced PD model, along with microglia activation. LRRK2 and P-P65 expression inhibition with PF-06447475 attenuated microglia activation in the nigrostriatal dense part of MPTP-treated mice. Based on our findings, it is evident that LRRK2 plays a critical role in promoting the neuroinflammatory response during the pathogenesis of PD by regulating the system Xc-GSH-GPX4 pathway. Taken together, our data highlights the potential research and therapeutic value of targeting LRRK2 to regulate neuroinflammatory response in PD through ferroptosis.

Protective effect of phenylpropionamides in the seed of Cannabis Sativa L. on Parkinson's disease through autophagy

Parkinson's disease (PD) is the second most common neurodegenerative disease in the world. As one of the major degradation pathways, autophagy plays a pivotal role in maintaining the effective turnover of proteins and damaged organelles in cells. Lewy bodies composed of α-synuclein (α-syn) abnormally aggregated in the substantia nigra are important pathological features of PD, and autophagy dysfunction is considered to be an important factor leading to abnormal aggregation of α-syn. Phenylpropionamides (PHS) in the seed of Cannabis sativa L. have a protective effect on neuroinflammation and antioxidant activity. However, the therapeutic role of PHS in PD is unclear. In this study, the seeds of Cannabis sativa L. were extracted under reflux with 60% EtOH-H2O, and the 60% EtOH-H2O elution fraction was identified as PHS with the UPLC-QTOF-MS. The 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridine (MPTP)-induced PD model in C57BL/6 J mice was used for behavioral and pharmacodynamic experiments. Behavioral symptoms were improved, Nissl-stained and TH-positive neurons in the substantia nigra were significantly increased in PHS-treated MPTP-induced PD model mice. Compared with the model group, PHS treatment reduced the expression level of α-syn, and the expression of TH increased significantly by western blotting, compared with the model group, the PHS group suppressed Caspase 3 and Bax expression and promoted Bcl-2 expression and levels of p62 decreased significantly, the ratio of LC3-II/I and p-mTOR/mTOR in the PHS group had a downward trend, suggesting that the therapeutic effect of PHS on MPTP-induced PD model mice may be triggered by the regulation of autophagy.

Imperatorin inhibits oxidative stress injury and neuroinflammation via the PI3K/AKT signaling pathway in the MPTP-induced Parkinson's disease mouse.

Parkinson's disease (PD) is a disorder of neurodegeneration. Imperatorin is an active natural furocoumarin characterized by antioxidant, anti-inflammatory, and potent vasodilatory properties. Therefore, we aimed to investigate the biological functions of imperatorin and its mechanisms against PD progression. C57BL/6 mice were intraperitoneally injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 30 mg/kg) daily for 5 consecutive days to mimic PD conditions in vivo. The MPTP-induced PD model mice were intraperitoneally injected with imperatorin (5 mg/kg) for 25 consecutive days after MPTP administration. The motor and cognitive functions of mice were examined by rotarod test, hanging test, narrow beam test and Morris water maze test. After analysis of MWM test, the expression levels of tyrosine hydroxylase and Iba-1 in the substantia nigra pars compacta were measured by immunohistochemistry staining, immunofluorescence staining and western blotting. The expression levels of striatal dopamine and its metabolite 3,4-dihydroxyphenylacetic acid were also measured. The protein levels of inducible nitric-oxide synthase, cyclooxygenase-2, phosphorylated phosphatidylinositol 3-kinase (PI3K) and phosphorylated protein kinase B (Akt) in the mouse striatum were estimated by western blotting. The expression levels of proinflammatory cytokines including tumor necrosis factor, interleukin (IL)-1β and IL-6 in the mouse striatum were measured by ELISA kits. The expression levels of superoxide dismutase, malondialdehyde and glutathione in the mouse midbrains were measured with commercially available kits. TUNEL staining was performed to identify the apoptosis of midbrain cells. Histopathologic changes in the mouse striata were assessed by hematoxylin-eosin staining. Imperatorin treatment markedly improved spatial learning and memory abilities of MPTP-induced PD mice. The MPTP-induced dopaminergic neuron loss in the mouse striata was inhibited by imperatorin. Imperatorin also suppressed neuroinflammation and neuronal oxidative stress in the midbrains of MPTP-induced PD mice. Mechanistically, imperatorin treatment inhibited the MPTP-induced reduction in the PI3K/Akt pathway. Imperatorin treatment can prevent dopaminergic neuron degeneration and improve cognitive functions via its potent antioxidant and anti-inflammatory properties in an MPTP-induced PD model in mice by regulating the PI3K/Akt pathway.

Amelioration of Astrocyte-Mediated Neuroinflammation by EI-16004 Confers Neuroprotection in an MPTP-induced Parkinson's Disease Model.

Parkinson's disease (PD) is a neurodegenerative disorder that results in motor impairment due to dopaminergic neuronal loss. The pathology of PD is closely associated with neuroinflammation, which can be characterized by astrocyte activation. Thus, targeting the inflammatory response in astrocytes might provide a novel therapeutic approach. We conducted a luciferase assay on an in-house chemical library to identify compounds with anti-inflammatory effects capable of reducing MPP+-induced NF-κB activity in astrocytes. Among the compounds identified, EI-16004, a novel 3-benzyl-N-phenyl-1H-pyrazole-5-carboxamides, exhibited a significant anti-inflammatory effect by significantly reducing MPP+-induced astrocyte activation. Biochemical analysis and docking simulation indicated that EI-16004 inhibited the MPP+-induced phosphorylation of p65 by attenuating ERK phosphorylation, and EI-16004 reduced pro-inflammatory cytokine and chemokine levels in astrocytes. In vivo studies on the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model in male C57BL/6 mice showed that EI-16004 ameliorated motor impairment and protected against dopaminergic neuronal loss, and EI-16004 effectively mitigated the MPTP-induced astrocyte activation in striatum (STR) and substantia nigra (SN). These results indicate EI-16004 is a potential neuroprotective agent for the prevention and treatment of astrocyte-mediated neuroinflammatory conditions in PD.

Secretory Clusterin Inhibits Dopamine Neuron Apoptosis in MPTP Mice by Preserving Autophagy Activity

Secretory clusterin (sCLU) plays an important role in the research progress of nervous system diseases. However, the physiological function of sCLU in Parkinson's disease (PD) are unclear. The purpose of this study was to examine the effects of sCLU-mediated autophagy on cell survival and apoptosis inhibition in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD. We found that MPTP administration induced prolonged pole-climbing time, shortened traction time and rotarod time, significantly decreased TH protein expression in the SN tissue of mice. In contrast, sCLU -treated mice took less time to climb the pole and had an extended traction time and rotating rod time. Meanwhile, sCLU intervention induced increased expression of the TH protein in the SN of mice. These results indicated that sCLU intervention could reduce the loss of dopamine neurons in the SN area and alleviate dyskinesia in mice. Furthermore, MPTP led to suppressed viability, enhanced apoptosis, an increased Bax/Bcl-2 ratio, and cleaved caspase-3 in the SN of mice, and these effects were abrogated by sCLU intervention. In addition, MPTP increased the levels of P62 protein, decreased Beclin1 protein, decreased the ratio of LC3B-II/LC3B-I, and decreased the numbers of autophagosomes and autophagolysosomes in the SN tissues of mice. These effects were also abrogated by sCLU intervention. Activation of PI3K/AKT/mTOR signaling with MPTP inhibited autophagy in the SN of MPTP mice; however, sCLU treatment activated autophagy in MPTP-induced PD mice by inhibiting PI3K/AKT/mTOR signaling. These data indicated that sCLU treatment had a neuroprotective effect in an MPTP-induced model of PD.

Itga5-PTEN signaling regulates striatal synaptic strength and motor coordination in Parkinson's disease.

Background: Parkinson's disease (PD) is marked by the loss of dopaminergic neurons in the substantia nigra pars compacta, leading to motor and cognitive dysfunctions. The molecular mechanisms underlying synaptic alterations in PD remain elusive, with a focus on the role of Itga5 in synaptic integrity and motor coordination and TAT-Itga5 was designed to suppress PTEN activity in this investigation. Methods: This study utilized MPTP-induced PD animal models to investigate the expression and role of Itga5 in the striatum. Techniques included quantitative PCR, Western blotting, immunostaining, CRISPR-CasRx-mediated knockdown, electrophysiological assays, behavioral tests, and mass spectrometry. Results: Itga5 expression was significantly reduced in MPTP-induced PD models. In these models, a marked decrease in dendritic spine density and a shift towards thinner spines in striatal GABA neurons were observed, suggesting impaired synaptic integration. Knockdown of Itga5 resulted in reduced dendritic branching, decreased mushroom spines, and increased thin spines, altering synaptic architecture. Electrophysiological analyses revealed changes in action potential and spontaneous excitatory postsynaptic currents, indicating altered synaptic transmission. Motor behavior assessments showed that Itga5 deficiency led to impairments in fine motor control and coordination. Furthermore, Itga5 was found to interact with PTEN, affecting AKT signaling crucial for synaptic development and motor coordination. Conclusion: The study demonstrates that Itga5 plays a critical role in maintaining synaptic integrity and motor coordination in PD. The Itga5-PTEN-AKT pathway represents a potential therapeutic target for addressing synaptic and motor dysfunctions in PD.

Neuro-Restorative Effect of Nimodipine and Calcitriol in 1-Methyl 4-Phenyl 1,2,3,6 Tetrahydropyridine-Induced Zebrafish Parkinson's Disease Model.

Parkinson's disease (PD) is one of the most prevalent neurodegenerative diseases, characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta. The treatment of PD aims to alleviate motor symptoms by replacing the reduced endogenous dopamine. Currently, there are no disease-modifying agents for the treatment of PD. Zebrafish (Danio rerio) have emerged as an effective tool for new drug discovery and screening in the age of translational research. The neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is known to cause a similar loss of dopaminergic neurons in the human midbrain, with corresponding Parkinsonian symptoms. L-type calcium channels (LTCCs) have been implicated in the generation of mitochondrial oxidative stress, which underlies the pathogenesis of PD. Therefore, we investigated the neuro-restorative effect of LTCC inhibition in an MPTP-induced zebrafish PD model and suggested a possible drug candidate that might modify the progression of PD. All experiments were conducted using a line of transgenic zebrafish, Tg(dat:EGFP), in which green fluorescent protein (GFP) is expressed in dopaminergic neurons. The experimental groups were exposed to 500 μmol MPTP from 1 to 3 days post fertilization (dpf). The drug candidates : levodopa 1 mmol, nifedipine 10 μmol, nimodipine 3.5 μmol, diethylstilbestrol 0.3 μmol, luteolin 100 μmol, and calcitriol 0.25 μmol were exposed from 3 to 5 dpf. Locomotor activity was assessed by automated tracking and dopaminergic neurons were visualized in vivo by confocal microscopy. Levodopa, nimodipine, diethylstilbestrol, and calcitriol had significant positive effects on the restoration of motor behavior, which was damaged by MPTP. Nimodipine and calcitriol have significant positive effects on the restoration of dopaminergic neurons, which were reduced by MPTP. Through locomotor analysis and dopaminergic neuron quantification, we identified the neuro-restorative effects of nimodipine and calcitriol in zebrafish MPTP-induced PD model. The present study identified the neuro-restorative effects of nimodipine and calcitriol in an MPTP-induced zebrafish model of PD. They restored dopaminergic neurons which were damaged due to the effects of MPTP and normalized the locomotor activity. LTCCs have potential pathological roles in neurodevelopmental and neurodegenerative disorders. Zebrafish are highly amenable to high-throughput drug screening and might, therefore, be a useful tool to work towards the identification of diseasemodifying treatment for PD. Further studies including zebrafish genetic models to elucidate the mechanism of action of the diseasemodifying candidate by investigating Ca2+ influx and mitochondrial function in dopaminergic neurons, are needed to reveal the pathogenesis of PD and develop disease-modifying treatments for PD.

Novel HDAC inhibitors provide neuroprotection in MPTP-induced Parkinson's disease model of rats

Parkinson's Disease (PD) is the most rapidly growing neurological disorder globally in terms of disability and mortality. While symptomatic treatment is available for PD, there is a critical unmet need for effective disease-modifying therapies. Recently, histone deacetylase inhibitors (HDACi), an important class of epigenetic modulators grabbed significant attention as drug targets for neurodegenerative diseases including PD. In this regard, novel pan-HDACi, cinnamyl sulphonamide hydroxamate derivatives (NMJ-2 and NMJ-3), synthesized and characterized in our laboratory, were screened for neuroprotective effects in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) rat model of PD. Twenty-four hours after the bilateral intranigral injection of MPTP, rats were administered orally with NMJ-2 or NMJ-3 (150 mg/kg) daily for 30 days. MPTP administration resulted in a marked rise in lipid peroxidation, and interleukin-1β concentration accompanied by reduced tyrosine hydroxylase and dopamine levels in the striatum compared to the sham group. These biochemical changes were associated with functional motor and non-motor deficits as revealed by loss of motor coordination (rota rod test), impaired grip strength (beam walk test), enhanced rigidity (catalepsy scores), loss of memory (novel object recognition test) and depressive-like behaviour (forced swim test). However, oral treatment with NMJ-2 or NMJ-3, or valproic acid for 30 days significantly attenuated the PD-induced adverse changes in motor and non-motor functions by ameliorating the oxidative stress as well as inflammation, and restoring the dopamine levels in the striatum comparable to the valproic acid group. These results suggest that targeting HDACi could be a rational therapeutic strategy for the development of disease-modifying therapies for PD.

SGLT2 inhibitor empagliflozin alleviates cardiac remodeling and contractile anomalies in a FUNDC1-dependent manner in experimental Parkinson's disease.

Recent evidence shows a close link between Parkinson's disease (PD) and cardiac dysfunction with limited treatment options. Mitophagy plays a crucial role in the control of mitochondrial quantity, metabolic reprogramming and cell differentiation. Mutation of the mitophagy protein Parkin is directly associated with the onset of PD. Parkin-independent receptor-mediated mitophagy is also documented such as BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3) and FUN14 domain containing 1 (FUNDC1) for receptor-mediated mitophagy. In this study we investigated cardiac function and mitophagy including FUNDC1 in PD patients and mouse models, and evaluated the therapeutic potential of a SGLT2 inhibitor empagliflozin. MPTP-induced PD model was established. PD patients and MPTP mice not only displayed pronounced motor defects, but also low plasma FUNDC1 levels, as well as cardiac ultrastructural and geometric anomalies (cardiac atrophy, interstitial fibrosis), functional anomalies (reduced E/A ratio, fractional shortening, ejection fraction, cardiomyocyte contraction) and mitochondrial injury (ultrastructural damage, UCP2, PGC1α, elevated mitochondrial Ca2+ uptake proteins MCU and VDAC1, and mitochondrial apoptotic protein calpain), dampened autophagy, FUNDC1 mitophagy and apoptosis. By Gene set enrichment analysis (GSEA), we found overtly altered glucose transmembrane transport in the midbrains of MPTP-treated mice. Intriguingly, administration of SGLT2 inhibitor empagliflozin (10 mg/kg, i.p., twice per week for 2 weeks) in MPTP-treated mice significantly ameliorated myocardial anomalies (with exception of VDAC1), but did not reconcile the motor defects or plasma FUNDC1. FUNDC1 global knockout (FUNDC1-/- mice) did not elicit any phenotype on cardiac geometry or function in the absence or presence of MPTP insult, but it nullified empagliflozin-caused cardioprotection against MPTP-induced cardiac anomalies including remodeling (atrophy and fibrosis), contractile dysfunction, Ca2+ homeostasis, mitochondrial (including MCU, mitochondrial Ca2+ overload, calpain, PARP1) and apoptotic anomalies. In neonatal and adult cardiomyocytes, treatment with PD neurotoxin preformed fibrils of α-synuclein (PFF) caused cytochrome c release and cardiomyocyte mechanical defects. These effects were mitigated by empagliflozin (10 μM) or MCU inhibitor Ru360 (10 μM). MCU activator kaempferol (10 μM) or calpain activator dibucaine (500 μM) nullified the empagliflozin-induced beneficial effects. These results suggest that empagliflozin protects against PD-induced cardiac anomalies, likely through FUNDC1-mediated regulation of mitochondrial integrity.

Thioredoxin-1 inhibits the activation of IRE1 by targeting Hsp90/p-Cdc37 chaperone complex in Parkinson disease.

Endoplasmic reticulum stress is implicated in the etiopathogenesis of Parkinson disease (PD). Our previous study has revealed that thioredoxin-1 (Trx-1) attenuated IRE1 activation in 1-methyl-4-phenylpyridinium ion (MPP+)/1-methy-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD models. However, its exact mechanism has been largely unclear. In this research, it was reported for the first time that the protein levels of heat shock protein 90 (Hsp90) and phosphorylated cell division cycle 37 (p-Cdc37) were significantly decreased and the interaction of Hsp90/p-Cdc37 complex with IRE1 was disturbed in MPP+/MPTP-induced PD models. Trx-1 overexpression reversed the expression of Hsp90 and p-Cdc37 in cultured cells and the substantia nigra pars compacta of mice. More importantly, Trx-1 overexpression enhanced the interaction of Hsp90/p-Cdc37 complex with IRE1. In conclusion, our data demonstrated that Trx-1 inhibited IRE1 activation in PD by elevating the expression of Hsp90 and p-Cdc37 and strengthening the interaction of Hsp90/p-Cdc37 complex and IRE1.

Effect of 4-AP on MPP+/ MPTP-induced Parkinson's disease model.

To study the effect of 4-AP on Parkinson's disease (PD) cells and animal model. PD cells were pretreated with different concentrations of 4-AP for 24 hours, then PD cells were prepared by MPP+, and the cell activity was detected by CCK8 kit. PD mice were prepared by MPTP and then given 4-AP for 10 days. Finally, the behavioral changes of mice were detected by pole climbing test and open field test, and the expression of TH in the midbrain was detected by IHC and WB. 4-AP could increase the activity of PD cells induced by MPP+. In the field experiment, the total spontaneous activity distance of PD mice (1380.01 ± 151.84) cm was not different from that of 4-AP intervention (1228.65 ± 358.25) cm but was reduced than that of normal mice (2121.89 ± 235.95) (P<0.05). In the pole climbing test, the pole climbing time of PD mice was (7.95 ± 1.02) seconds, compared with that of PD mice treated with 4-AP, there was no difference between the two groups, but it was reduced than that of normal mice (P<0.05). IHC and Western blot showed that the mesencephalic TH of PD mice and drug-treated mice were reduced than that of normal mice (P<0.05), however, drug intervention could not reduce the expression of TH in mice with PD (P>0.5). 4-AP pretreatment can reduce the toxic and side effects of MPP+. 4-AP can not improve the motor function impairment of PD mice, nor can it reduce the toxic effect of MPTP on dopaminergic neurons. There are differences between pre-treatment and post-intervention in the treatment of MPP+/MPTP-induced PD. In order to better explore the drug treatment and target of PD, it is hoped that a cure for PD can be found in PD animals. The timing of intervention and cell and animal experiments should complement each other.

Association between SGK1 and α-synuclein in skeletal muscle in an MPTP-induced Parkinson's disease model

Parkinson's disease (PD) is a neurodegenerative disease caused by loss of dopaminergic neurons in the substantia nigra and it is known to involve the accumulation of α-synuclein (α-syn), which is a neuroprotein that promotes degeneration of dopaminergic neurons. Serum/glucocorticoid-related kinase 1 (SGK1) is involved in the physiological and pathological processes in neurons. The aim of this study was to examine the relationship between SGK1 and α-syn expression in muscle tissue of a PD model and in C2C12 cells. Western blotting, immunohistochemistry, and immunofluorescence microscopy confirmed reduced SGK1 and increased α-syn expression in skeletal muscle of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice compared to the control group. To determine the relationship between SGK1 and α-syn, SGK1 small interfering RNA (siRNA) knockdown was performed in C2C12 cells, which showed that suppression of SGK1 levels resulted in increased α-syn expression. The main finding of our study is that reduction of SGK1 expression contributes to the pathogenesis of PD by increasing the expression of α-syn in skeletal muscle of MPTP-treated mice and C2C12 cells. This study confirms that decreased SGK1 induces increased α-syn expression in skeletal muscle, which suggests that maintaining SGK1 expression may improve PD symptoms.

Fecal Microbiota Transplantation from Aged Mice Render Recipient Mice Resistant to MPTP-Induced Nigrostriatal Degeneration Via a Neurogenesis-Dependent but Inflammation-Independent Manner.

Accumulating data support a crucial role of gut microbiota in Parkinson's disease (PD). However, gut microbiota vary with age and, thus, will affect PD in an age-dependent, but unknown manner. We examined the effects of fecal microbiota transplantation (FMT) pretreatment, using fecal microbiota from young (7weeks) or aged mice (23months), on MPTP-induced PD model. Motor function, pathological changes, striatal neurotransmitters, neuroinflammation, gut inflammation and gut permeability were examined. Gut microbiota composition and metabolites, namely short-chain fatty acids (SCFAs), were analyzed. Neurogenesis was also evaluated by measuring the number of doublecortin-positive (DCX+) neurons and Ki67-positive (Ki67+) cells in the hippocampus. Expression of Cd133 mRNA, a cellular stemness marker, in the hippocampus was also examined. Mice who received FMT from young mice showed MPTP-induced motor dysfunction, and reduction of striatal dopamine (DA), dopaminergic neurons and striatal tyrosine hydroxylase (TH) levels. Interestingly and unexpectedly, mice that received FMT from aged mice showed recovery of motor function and rescue of dopaminergic neurons and striatal 5-hydroxytryptamine (5-HT), as well as decreased DA metabolism after MPTP challenge. Further, they showed improved metabolic profiling and a decreased amount of fecal SCFAs. High-throughput sequencing revealed that FMT remarkably reshaped the gut microbiota of recipient mice. For instance, levels of genus Akkermansia and Candidatus Saccharimonas were elevated in fecal samples of recipient mice receiving aged microbiota (AM + MPTP mice) than YM + MPTP mice. Intriguingly, both young microbiota and aged microbiota had no effect on neuroinflammation, gut inflammation or gut permeability. Notably, AM + MPTP mice showed a marked increase in DCX+ neurons, as well as Ki67+ cells and Cd133 expression in the hippocampal dentate gyrus (DG) compared to YM + MPTP mice. These results suggest that FMT from aged mice augments neurogenesis, improves motor function and restores dopaminergic neurons and neurotransmitters in PD model mice, possibly through increasing neurogenesis.