Chicoric Acid Prevents Neuroinflammation and Neurodegeneration in a Mouse Parkinson's Disease Model: Immune Response and Transcriptome Profile of the Spleen and Colon.

Chicoric acid (CA), a polyphenolic acid compound extracted from chicory and echinacea, possesses antiviral, antioxidative and anti-inflammatory activities. Growing evidence supports the pivotal roles of brain-spleen and brain-gut axes in neurodegenerative diseases, including Parkinson's disease (PD), and the immune response of the spleen and colon is always the active participant in the pathogenesis and development of PD. In this study, we observe that CA prevented dopaminergic neuronal lesions, motor deficits and glial activation in PD mice, along with the increment in striatal brain-derived neurotrophic factor (BDNF), dopamine (DA) and 5-hydroxyindoleacetic acid (5-HT). Furthermore, CA reversed the level of interleukin-17(IL-17), interferon-gamma (IFN-γ) and transforming growth factor-beta (TGF-ß) of PD mice, implicating its regulatory effect on the immunological response of spleen and colon. Transcriptome analysis revealed that 22 genes in the spleen (21 upregulated and 1 downregulated) and 306 genes (190 upregulated and 116 downregulated) in the colon were significantly differentially expressed in CA-pretreated mice. These genes were functionally annotated with GSEA, GO and KEGG pathway enrichment, providing the potential target genes and molecular biological mechanisms for the modulation of CA on the spleen and gut in PD. Remarkably, CA restored some gene expressions to normal level. Our results highlighted that the neuroprotection of CA might be associated with the manipulation of CA on brain-spleen and brain-gut axes in PD.

Protective effects of prucalopride in MPTP-induced Parkinson's disease mice: Neurochemistry, motor function and gut barrier.

Evidence suggests constipation precedes motor dysfunction and is the most common gastrointestinal symptom in Parkinson's disease (PD). 5-HT4 receptor (5-HT4R) agonist prucalopride has been approved to treat chronic constipation. Here, we reported intraperitoneal injection of prucalopride for 7 days increased dopamine and decreased dopamine turnover. Prucalopride administration improved motor deficits in 1-methyl-4-phenyl-1,2,3,6-tetrathydropyridine (MPTP)-induced PD mouse models. Prucalopride treatment also ameliorated intestinal barrier impairment and increased IL-6 release in PD model mice. However, prucalopride treatment exerted no impact on JAK2/STAT3 pathway, suggesting that prucalopride may stimulate IL-6 via JAK2/STAT3-independent pathway. In conclusion, prucalopride exerted beneficial effects in MPTP-induced Parkinson's disease mice by attenuating the loss of dopamine, improving motor dysfunction and intestinal barrier.

Polygonatum sibiricum Polysaccharides Protect against MPP-Induced Neurotoxicity via the Akt/mTOR and Nrf2 Pathways.

Polygonatum sibiricum, a well-known life-prolonging tonic in Chinese medicine, has been widely used for nourishing nerves in the orient, but the underlying molecular mechanisms remain unclear. In this study, we found that P. sibiricum polysaccharides (PSP) ameliorated 1-methyl-4-phenyl-1,2.3,6-tetrahydropyridine- (MPTP-) induced locomotor activity deficiency and dopaminergic neuronal loss in an in vivo Parkinson's disease (PD) mouse model. Additionally, PSP pretreatment inhibited N-methyl-4-phenylpyridine (MPP+) induced the production of reactive oxygen species, increasing the ratio of reduced glutathione/oxidized glutathione. In vitro experiments showed that PSP promoted the proliferation of N2a cells in a dose-dependent manner, while exhibiting effects against oxidative stress and neuronal apoptosis elicited by MPP+. These effects were found to be associated with the activation of Akt/mTOR-mediated p70S6K and 4E-BP1 signaling pathways, as well as nuclear factor erythroid 2-related factor 2- (Nrf2-) mediated NAD(P)H quinone oxidoreductase 1 (NQO1), heme oxygenase-1 (HO-1), glutamate-cysteine ligase catalytic subunit (Gclc), and glutamate-cysteine ligase modulatory subunit (Gclm), resulting in antiapoptotic and antioxidative effects. Meanwhile, PSP exhibited no chronic toxicity in C57BJ/6 mice. Together, our results suggest that PSP can serve as a promising therapeutic candidate with neuroprotective properties in preventing PD.

Protection by rhynchophylline against MPTP/MPP+-induced neurotoxicity via regulating PI3K/Akt pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Isolated from Uncaria rhynchophylla (U. rhynchophylla), rhynchophylline (Rhy) has been applied for treating diseases related to central nervous system such as Parkinson's disease. Nevertheless, the molecular mechanism of the neuroprotective effect has not been well interpreted. AIM OF THE STUDY: To investigate the effects of Rhy on MPTP/MPP + -induced neurotoxicity in C57BL/6 mice or PC12 cells and study the mechanisms involved. MATERIALS AND METHODS: The neuroprotective effect of Rhy on MPTP-induced neurotoxicity was evaluated by spontaneous motor activity test, as well as a test of rota-rod on a rat model of Parkinson's disease. The numbers of TH-positive neurons in the substantia nigra pars compacta (SNpc) was assessed by immunohistological. CCK-8, lactate dehydrogenase (LDH), reactive oxygen species (ROS), the concentration of intracellular calcium ([Ca2+]i) and flow cytometry analysis were performed to evaluate the pharmacological property of Rhy on 1-methyl-4-phenylpyridinium (MPP+) induced neurotoxicity in PC12 cells. Besides, LY294002, a PI3K inhibitor was employed to determine the underlying molecular signaling pathway revealing the effect of Rhy by western-blot analysis. RESULTS: The results showed that Rhy exhibited a protective effect against the MPTP-induced decrease in tyrosine hydroxylase (TH)-positive fibers in the substantia nigra at 30 mg/kg, demonstrated by the immunohistological and behavioral outcomes. Furthermore, it has been indicated that cell viability was improved and the MPP+-induced apoptosis was inhibited after the treatment of Rhy at 20 µM, which were severally analyzed by the CCK-8 and the Annexin V/propidium iodide staining method. In addition, Rhy treatment attenuated MPP+-induced up-regulation of LDH, ([Ca2+]i), and the levels of ROS. Besides, it can be revealed from the Western blot assay that LY294002, as a selective Phosphatidylinositol 3-Kinase (PI3K) inhibitor, effectively inhibited the Akt phosphorylation caused by Rhy, which suggested that Rhy showed its protective property through the activated the PI3K/Akt signaling pathway. Moreover, the Rhy-induced decreases of Bax and caspase-3 as the proapoptotic markers and the increase of Bcl-2 as the antiapoptotic marker, were blocked by LY294002 in the MPP+-treated PC12 cells. CONCLUSIONS: Rhy exerts a neuroprotective effect is partly mediated by activating the PI3K/Akt signaling pathway.

Brain Selective Estrogen Treatment Protects Dopaminergic Neurons and Preserves Behavioral Function in MPTP-induced Mouse Model of Parkinson's Disease.

Parkinson's disease (PD) is characterized by progressive degeneration of dopaminergic neurons in the substantia nigra and loss of both motor and non-motor features. Several clinical and preclinical studies have provided evidence that estrogen therapy reduces the risk of PD but have limitations in terms of adverse peripheral effects. Therefore, we examined the potential beneficial effects of the brain-selective estrogen prodrug, 10ß, 17ß-dihydroxyestra-1,4-dien-3-one (DHED) on nigrostriatal dopaminergic neurodegeneration and behavioral abnormalities in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. Wild-type mice were treated with daily subcutaneous injections of DHED (50 and 100 µg/kg) or vehicle for four weeks. To produce PD-like symptoms, mice were injected with MPTP (18 mg/kg in saline; intraperitoneally) four times at 2-hr intervals for one day. After behavioral examination, mice were sacrificed, and the brains were isolated for neurochemical and morphological examinations. MPTP injected mice exhibited loss of dopaminergic neurons and fibers in substantia nigra and striatum respectively, along with impaired motor function at day 7 post MPTP injection. These phenotypes were associated with significantly increased oxidative stress and inflammatory responses in the striatum regions. DHED treatments significantly mitigated behavioral impairments and dopaminergic neurodegeneration induced by MPTP. We further observed that DHED treatment suppressed oxidative stress and inflammation in the striatum of MPTP treated mice when compared to vehicle treated mice. In conclusions, our findings suggest that DHED protects dopaminergic neurons from MPTP toxicity in mouse model of PD and support a beneficial effect of brain-selective estrogen in attenuating neurodegeneration and motor symptoms in PD-related neurological disorders. Graphical Abstract.

Botanical Drug Puerarin Promotes Neuronal Survival and Neurite Outgrowth against MPTP/MPP+-Induced Toxicity via Progesterone Receptor Signaling.

BACKGROUND: Progesterone receptor (PR) modulates neuroprotective and regenerative responses in Parkinson's disease and related neurological diseases. OBJECTIVES: The present study was designed to determine whether botanical drug puerarin could exhibit neuroprotective and neurorestorative activities via PR signaling. METHODS: The neuroprotective and neurotrophic activities of puerarin were investigated in MPTP-lesioned mice and MPP+-challenged primary rat midbrain neurons. Rotarod performance test and tail suspension test were used to assess motor functions. Tyrosine hydroxylase (TH) and PR were determined by immunostaining, Western blotting, and luciferase reporter assays. Neurite outgrowth was assessed by fluorescence staining and immunostaining. RESULTS: Puerarin effectively ameliorated the MPTP-induced motor abnormalities in MPTP-lesioned mice and protected primary rat midbrain neurons against MPP+-induced toxicity via PR signaling although progesterone exhibited the neuroprotection. PR antagonist mifepristone (RU486) diminished the neuroprotection of puerarin in MPTP-lesioned mice and MPP+-induced primary rat midbrain neurons. Moreover, puerarin promoted the differentiation of primary rat midbrain neurons and potentiated NGF to induce neuritogenesis in PC12 cells. RU486 and PR-siRNA could inhibit the effect of puerarin. Puerarin and progesterone could enhance the PR promoter. CONCLUSION: Puerarin attenuated MPTP- and MPP+-induced toxicity and potentiated neurite outgrowth via PR. These results suggested that puerarin may become an alternative hormone for suppressing MPTP- and MPP+-induced toxicity in neurodegenerative diseases.

IGF-1 inhibits MPTP/MPP+-induced autophagy on dopaminergic neurons through the IGF-1R/PI3K-Akt-mTOR pathway and GPER.

Autophagy dysfunctions are involved in the pathogenesis of Parkinson's disease (PD). In the present study, we aimed to evaluate the involvement of G protein-coupled estrogen receptor (GPER) in the inhibitory effect of insulin-like growth factor-1 (IGF-1) against excessive autophagy in PD animal and cellular models. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment significantly induced mouse movement disorder and decreased the protein level of tyrosine hydroxylase (TH) in the substantia nigra (SN) and dopamine (DA) content in striatum. Along with the dopamine neuron injury, we observed significant upregulations of microtubule-associated light chain-3 II (LC3-II) and α-synuclein as well as a downregulation of P62 in MPTP-treated mice. These changes could be restored by IGF-1 pretreatment. Cotreatment with IGF-1R antagonist JB-1 or GPER antagonist G15 could block the neuroprotective effects of IGF-1. 1-Methy-4-phenylpyridinium (MPP+) treatment could also excessively activate autophagy along with the reduction of cell viability in SH-SY5Y cells. IGF-1 could inhibit the neurotoxicity through promoting the phosphorylation of Akt and mammalian target of rapamycin (mTOR), which could also be antagonized by JB-1 or G15. These data suggest that IGF-1 inhibits MPTP/MPP+-induced autophagy on dopaminergic neurons through the IGF-1R/PI3K-Akt-mTOR pathway and GPER.

Neuroprotective Activities of Long-Acting Granulocyte-Macrophage Colony-Stimulating Factor (mPDM608) in 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine-Intoxicated Mice.

Loss of dopaminergic neurons along the nigrostriatal axis, neuroinflammation, and peripheral immune dysfunction are the pathobiological hallmarks of Parkinson's disease (PD). Granulocyte-macrophage colony-stimulating factor (GM-CSF) has been successfully tested for PD treatment. GM-CSF is a known immune modulator that induces regulatory T cells (Tregs) and serves as a neuronal protectant in a broad range of neurodegenerative diseases. Due to its short half-life, limited biodistribution, and potential adverse effects, alternative long-acting treatment schemes are of immediate need. A long-acting mouse GM-CSF (mPDM608) was developed through Calibr, a Division of Scripps Research. Following mPDM608 treatment, complete hematologic and chemistry profiles and T-cell phenotypes and functions were determined. Neuroprotective and anti-inflammatory capacities of mPDM608 were assessed in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-intoxicated mice that included transcriptomic immune profiles. Treatment with a single dose of mPDM608 resulted in dose-dependent spleen and white blood cell increases with parallel enhancements in Treg numbers and immunosuppressive function. A shift in CD4+ T-cell gene expression towards an anti-inflammatory phenotype corresponded with decreased microgliosis and increased dopaminergic neuronal cell survival. mPDM608 elicited a neuroprotective peripheral immune transformation. The observed phenotypic shift and neuroprotective response was greater than observed with recombinant GM-CSF (rGM-CSF) suggesting human PDM608 as a candidate for PD treatment.

LncRNA H19 Attenuates Apoptosis in MPTP-Induced Parkinson's Disease Through Regulating miR-585-3p/PIK3R3.

Parkinson's disease (PD) is a prevalent age-related neurodegenerative disease which is modulated by various molecules, including long non-coding RNAs (lncRNAs). LncRNA H19 has been shown to be associated with PD progression, but the mechanism is still unclear. This research aims to investigate the role of H19 in PD development and the detailed mechanisms. Our results showed that H19 was down-regulated in brain tissue of MPTP-induced PD mice (in vivo) and in MPP+ treated human neuroblastoma cells. miR-585-3p was verified to be a target of lncRNA H19 and was negatively regulated by H19. In addition, H19 could increase the expression of PIK3R3 through miR-585-3p. In vitro results indicated that H19 inhibited the apoptosis of MPP+ treated neuroblastoma cells by regulating of miR-585-3p. Moreover, in PD model mice, overexpression of H19 attenuated MPTP-induced neuronal apoptosis. In summary, our present research demonstrated that LncRNA H19 could attenuate neurons apoptosis in MPTP-induced PD mice as well as MPP+ treated neuroblastoma cells through regulating miR-585-3p/PIK3R3. The results may provide a potential theoretical experimental data for the clinical treatment of PD through targeting lncRNAs or miRNAs.

Luteolin-7-O-glucoside protects dopaminergic neurons by activating estrogen-receptor-mediated signaling pathway in MPTP-induced mice.

BACKGROUND: Parkinson's disease (PD) is a neurodegenerative disorder that is characterized by the degeneration of dopaminergic neurons in substantia nigra (SN). Accumulating evidences implicate the beneficial role of estrogen in the therapy of PD. METHODS: In the present study, the protective function of luteolin-7-O-glucoside (LUT-7G), a natural flavonoid, was investigated in 1-methyl-4-phenylpyridinium (MPP+) treated SH-SY5Y cells and 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) induced mice. RESULTS: Pre-treatment of LUT-7G increased the viability and reduced the apoptosis of SH-SY5Y cells treated by MPP+. At molecular level, the Bcl-2/Bax ratio was increased, while the expression of cleaved caspase 3 was markedly lessened. Moreover, LUT-7G increased the expression of estrogen receptor (ER), ERα and ERß, and enhanced the activation of ERK1/2/STAT3/c-Fos that could be abolished by ER antagonists. Furthermore, in vivo experiment indicated that pre-treatment of LUT-7G improved the bradykinesia, and enhanced the muscle strength as well as the balancing capacity of mice treated with MPTP. And LUT-7G prevented the injury of TH positive cells in substantia nigra and increased TH positive nerve fibers in striatum. In addition, pre-treatment of LUT-7G also significantly diminished the MPTP-induced gliosis in substantia nigra. CONCLUSIONS: LUT-7G effectively protected dopaminergic neurons against MPP+ or MPTP-induced toxicity, probably by activating the ER-mediated signaling pathway. Our findings explore the therapeutic potential of LUT-7G for PD therapy.

Neuroprotective effect of anodal transcranial direct current stimulation on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity in mice through modulating mitochondrial dynamics.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the accumulation of protein inclusions and the loss of dopaminergic neurons. Abnormal mitochondrial homeostasis is thought to be important for the pathogenesis of PD. Transcranial direct current stimulation (tDCS), a noninvasive brain stimulation technique, constitutes a promising approach for promoting recovery of various neurological conditions. However, little is known about its mechanism of action. The present study elucidated the neuroprotective effects of tDCS on the mitochondrial quality control pathway in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model. We used the MPTP-induced neurotoxicity in vivo model. Mice were stimulated for 5 consecutive days with MPTP treatment. After observation of behavioral alteration using the rotarod test, mice were sacrificed for the measurement of the PD- and mitochondrial quality control-related protein levels in the substantia nigra. tDCS improved the behavioral alterations and changes in tyrosine hydroxylase levels in MPTP-treated mice. Furthermore, tDCS attenuated mitochondrial damage, as indicated by diminished mitochondrial swelling and mitochondrial glutamate dehydrogenase activity in the MPTP-induced PD mouse model. MPTP significantly increased mitophagy and decreased mitochondrial biogenesis-related proteins. These changes were attenuated by tDCS. Furthermore, MPTP significantly increased fission-related protein dynamin-related protein 1 with no effect on fusion-related protein mitofusin-2, and tDCS attenuated these changes. Our findings demonstrated the neuroprotective effect of anodal tDCS on the MPTP-induced neurotoxic mouse model through suppressing excessive mitophagy and balancing mitochondrial dynamics. The neuroprotective effect of anodal tDCS with modulation of mitochondrial dynamics provides a new therapeutic strategy for the treatment of PD.

Dietary intake of glucoraphanin prevents the reduction of dopamine transporter in the mouse striatum after repeated administration of MPTP.

AIMS: Parkinson's disease (PD) is a chronic and progressive neurodegenerative disorder. Although diet may influence the development of PD, the precise mechanisms underlying relationship between diet and PD pathology are unknown. Here, we examined whether dietary intake of glucoraphanin (GF), the precursor of a natural antioxidant sulforaphane in cruciferous vegetables, can affect the reduction of dopamine transporter (DAT) in the mouse striatum after repeated administration of MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine). METHODS: Normal food pellet or 0.1% GF food pellet was given into male mice for 28 days from 8-week-old. Subsequently, saline (5 mL/kg × 3, 2-hour interval) or MPTP (10 mg/kg × 3, 2-hour interval) was injected into mice. Immunohistochemistry of DAT in the striatum was performed 7 days after MPTP injection. RESULTS: Repeated injections of MPTP significantly decreased the density of DAT-immunoreactivity in the mouse striatum. In contrast, dietary intake of 0.1% GF food pellet significantly protected against MPTP-induced reduction of DAT-immunoreactivity in the striatum. CONCLUSION: This study suggests that dietary intake of GF food pellet could prevent MPTP-induced dopaminergic neurotoxicity in the striatum of adult mice. Therefore, dietary intake of GF-rich cruciferous vegetables may have beneficial effects on prevention for development of PD.

5-(3,4-Difluorophenyl)-3-(6-methylpyridin-3-yl)-1,2,4-oxadiazole (DDO-7263), a novel Nrf2 activator targeting brain tissue, protects against MPTP-induced subacute Parkinson's disease in mice by inhibiting the NLRP3 inflammasome and protects PC12 cells against oxidative stress.

Parkinson's disease (PD) is the second most common aging-related neurodegenerative disease worldwide. Oxidative stress and neuroinflammation are critical events in the degeneration of dopaminergic neurons in PD. In this study, we found that DDO-7263, a novel Nrf2-ARE activator reported by us, has ideal therapeutic effects on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease in mice. DDO-7263 improved the behavioral abnormalities induced by MPTP in mice, significantly attenuated chemically induced dopaminergic neuron loss of tyrosine hydroxylase (TH) in the substantia nigra (SN) and striatum of the mouse brain and inhibited the secretion of inflammatory factors. In addition, DDO-7263 protected PC12 neurons from H2O2-induced oxidative damage. The neuroprotective effects of DDO-7263 were confirmed both in vitro and in vivo models. Further studies showed that the neuroprotective effect of DDO-7263 was mediated by the activation of Nrf2-ARE signaling pathway and the inhibition of NLRP3 inflammasome activation. DDO-7263 induced NLRP3 inflammasome inhibition is dependent on Nrf2 activation. This conclusion was also verified in THP-1-derived macrophages (THP-Ms). DDO-7263 significantly inhibited NLRP3 activation, cleaved caspase-1 production and IL-1ß protein expression in ATP-LPS-exposed THP-Ms cells. The pharmacokinetic parameters and tissue distribution results indicated that DDO-7263 has a brain tissue targeting function. All these lines of evidence show that DDO-7263 has ideal therapeutic effects on neurodegenerative diseases such as PD.

Neuroprotective effects of Tat-ATOX1 protein against MPP+-induced SH-SY5Y cell deaths and in MPTP-induced mouse model of Parkinson's disease.

Parkinson's disease (PD), a neurodegenerative disorder, is characterized by a loss of dopaminergic neurons in the substantia nigra (SN) of the brain and it is well known that the pathogenesis of PD is related to a number of risk factors including oxidative stress. Antioxidant 1 (ATOX1) protein plays a crucial role in various diseases as an antioxidant and chaperone. In this study, we determined whether Tat-ATOX1 could protect against 1-methyl-4-phenylpyridinium ion (MPP+)-induced SH-SY5Y cell death and in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced animal model of PD. In the MPP+ exposed SH-SY5Y cells, Tat-ATOX1 markedly inhibited cell death and toxicities. In addition, Tat-ATOX1 markedly suppressed the activation of Akt and mitogen activated protein kinases (MAPKs) as well as cleavage of caspase-3 and Bax expression levels. In a MPTP-induced animal model, Tat-ATOX1 transduced into brain and protected dopaminergic neuronal cell loss. Taken together, Tat-ATOX1 inhibits dopaminergic neuronal death through the suppression of MAPKs and apoptotic signal pathways. Thus, Tat-ATOX1 represents a potential therapeutic protein drug candidate for PD.

Salidroside protected against MPP+ -induced Parkinson's disease in PC12 cells by inhibiting inflammation, oxidative stress and cell apoptosis.

The present study aimed to investigate the protective effects of salidroside (SAL) on 1-methyl-4-phenylpyridinium (MPP+ )-induced PC12 cell model for Parkinson's disease. PC12 cells were pretreated with SAL in different concentrations and then exposed to MPP+ . To evaluate the effects of SAL on cytotoxicity, the survival rate was tested by the 3-(4,5-dimethylthiazol-2-yl)-2,5-dimethyltetrazolium bromide (MTT) assay and the apoptosis was tested via flow cytometry and Western blot. Reactive oxygen species (ROS), glutathione (GSH), and malondialdehyde (MDA) were detected to analyze the effects of SAL on oxidative stress. The mRNA and protein levels of inflammatory factors TNF-α and IL-1ß were also determined by real-time quantitative polymerase chain reaction and Western blot. Pretreatment with SAL effectively relieved the MPP+ cytotoxic effects and decreased the release of ROS production and inflammatory cytokines. SAL also inhibited apoptosis, suppressed MDA activity, and increased GSH levels in MPP+ -treated PC12 cells. Moreover, the expression levels of caspase-9, caspase-3, and Bax were significantly decreased in the SAL treatment groups compared with the MPP+ group, whereas Bcl-2 expression was significantly increased in the SAL treatment groups. In summary, the overall results suggested that SAL have neuroprotective effects on the MPP+ -induced PC12 cell model by inhibiting inflammation, oxidative stress, and cell apoptosis. SAL may be a potential active product to protect against Parkinson's disease.

Pramipexole and Fingolimod exert neuroprotection in a mouse model of Parkinson's disease by activation of sphingosine kinase 1 and Akt kinase.

Parkinson's disease (PD) is one of the most severe neurodegenerative diseases with unknown pathogenesis and currently unsuccessful therapies. Recently, neuroprotection via sphingosine-1-phosphate (S1P)-dependent signalling has become a promising target for the treatment of neurodegenerative disorders. Our previous study demonstrated down-regulation and inhibition of the S1P-synthesizing enzyme sphingosine kinase 1 (SPHK1) in a PD cellular model. Moreover, we have previously identified a neuroprotective effect of fingolimod (FTY720), a first S1P receptor modulator utilized in the clinic. This study focused on the effects of FTY720 and the dopamine D2/D3 receptor agonist pramipexole (PPX) in a PD mouse model, induced by administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Administration of FTY720, similar to PPX, abolished an observed loss of tyrosine hydroxylase (TH) immunoreactivity in MPTP-lesioned brain regions. Moreover, significant changes in SPHK1 expression/activity in MPTP-lesioned mouse midbrain were identified. PPX, but not FTY720 treatment, significantly protected against these alterations. Both drugs activate another pro-survival enzyme, Akt kinase, which is a crucial protein downstream of S1PR(s). FTY720 increased BAD protein phosphorylation and in this way may protect mitochondria against the BAD-induced apoptotic signalling pathway. Both FTY720 and PPX enhanced the locomotor activity of PD mice in the rotarod tests. Our data suggest a neuroprotective role for FTY720 related to the S1PR/Akt kinase signalling pathways as a beneficial treatment target in planning new PD therapeutic options. Moreover, our findings have shed new light on a neuroprotective mechanism of PPX action associated with SPHK1 activation, which provides an opportunity for evaluating multi-target (SPHK1/S1P/S1PR) effects in the context of PD.

Defective trafficking of Kv2.1 channels in MPTP-induced nigrostriatal degeneration.

Intracellular protein trafficking is tightly regulated, and improper trafficking might be the fundamental provocateur for human diseases including neurodegeneration. In neurons, protein trafficking to and from the plasma membrane affects synaptic plasticity. Voltage-gated potassium channel 2.1 (Kv2.1) is a predominant delayed rectifier potassium (K+ ) current, and electrical activity patterns of dopamine (DA) neurons within the substantia nigra are generated and modulated by the orchestrated function of different ion channels. The pathological hallmark of Parkinson's disease (PD) is the progressive loss of these DA neurons, resulting in the degeneration of striatal dopaminergic terminals. However, whether trafficking of Kv2.1 channels contributes to PD remains unclear. In this study, we demonstrated that MPTP/MPP+ increases the surface expression of the Kv2.1 channel and causes nigrostriatal degeneration by using a subchronic MPTP mouse model. The inhibition of the Kv2.1 channel by using a specific blocker, guangxitoxin-1E, protected nigrostriatal projections against MPTP/MPP+ insult and thus facilitated the recovery of motor coordination. These findings highlight the importance of trafficking of Kv2.1 channels in the pathogenesis of PD.

Atorvastatin Prevents Early Oxidative Events and Modulates Inflammatory Mediators in the Striatum Following Intranasal 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) Administration in Rats.

Atorvastatin is a 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor with cholesterol-lowering, anti-inflammatory, and antioxidant properties. Increasing evidence show atorvastatin acts as a protective agent against insults in the central nervous system (CNS). The regular use of statins has been associated with a reduced risk of Parkinson's disease (PD) development. Here, we evaluated early events involved in the neurotoxicity induced by intranasal (i.n.) infusion of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in rats and the potential of atorvastatin to prevent these early toxic events. Male Wistar rats were pretreated orally with atorvastatin (10 mg/kg/day) or vehicle once a day during seven consecutive days. Twenty-four hours after atorvastatin administration, animals received a single bilateral i.n. infusion of MPTP (1 mg/nostril), and 6 h later, the striatum and the hippocampus were collected to evaluate early oxidative stress parameters and inflammatory cytokines. Atorvastatin prevented MPTP-induced increase in reactive species (RS) generation and in glutathione levels in the striatum. Atorvastatin also prevented the reduction in mitochondrial respiratory chain complex I and II activities evoked by MPTP in the striatum. Atorvastatin per se reduced the levels of the cytokines TNF-α and IL-1ß, and surprisingly, it reduced IL-10 and nerve growth factor levels in the striatum. However, the anti-inflammatory IL-10 levels increased in the striatum following atorvastatin plus MPTP treatment. These effects were not observed in the hippocampus. Our findings reinforce and extend the notion of the neuroprotective effects of atorvastatin in a PD model and indicate the modulation of oxidative and inflammatory responses as the mechanisms associated with therapeutic action of atorvastatin in PD.

Activation of the Nrf2 signaling pathway and neuroprotection of nigral dopaminergic neurons by a novel synthetic compound KMS99220.

The transcription factor Nrf2 is known to induce gene expression of antioxidant enzymes and proteasome subunits. Because both oxidative stress and protein aggregation have damaging effects on neurons, activation of the Nrf2 signaling should be beneficial against neurodegeneration. In this study, we report a novel synthetic morpholine-containing chalcone KMS99220 that confers neuroprotection. It showed high binding affinity to the Nrf2 inhibitory protein Keap-1 and increased nuclear translocation of Nrf2 and gene expression of the antioxidant enzymes heme oxygenase-1, NAD(P)H:quinone oxidoreductase-1, and the catalytic and modifier subunits of glutamate-cysteine ligase in dopaminergic CATH.a cells. KMS99220 also increased expression of the proteasome subunits PSMB5, PSMB7, PSMB8 and PSMA1, and the respective chymotrypsin and trypsin-like proteasomal enzyme activities, and reduced α-synuclein aggregate in GFP-α-syn A53T-overexpressing cells. KMS99220 exhibited a favorable pharmacokinetic profile with excellent bioavailability and metabolic stability, did not interfere with activities of the cytochrome p450 isotypes, and showed no apparent in vivo toxicity when administered up to 2000 mg/kg. In 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated mice, oral administration of KMS99220 prevented degeneration of the nigral dopaminergic neurons, induced the Nrf2 target genes, and effectively prevented the associated motor deficits. These results suggest KMS99220 as a potential candidate for therapy against Parkinson's disease.

KEAP1-modifying small molecule reveals muted NRF2 signaling responses in neural stem cells from Huntington's disease patients.

The activity of the transcription factor nuclear factor-erythroid 2 p45-derived factor 2 (NRF2) is orchestrated and amplified through enhanced transcription of antioxidant and antiinflammatory target genes. The present study has characterized a triazole-containing inducer of NRF2 and elucidated the mechanism by which this molecule activates NRF2 signaling. In a highly selective manner, the compound covalently modifies a critical stress-sensor cysteine (C151) of the E3 ligase substrate adaptor protein Kelch-like ECH-associated protein 1 (KEAP1), the primary negative regulator of NRF2. We further used this inducer to probe the functional consequences of selective activation of NRF2 signaling in Huntington's disease (HD) mouse and human model systems. Surprisingly, we discovered a muted NRF2 activation response in human HD neural stem cells, which was restored by genetic correction of the disease-causing mutation. In contrast, selective activation of NRF2 signaling potently repressed the release of the proinflammatory cytokine IL-6 in primary mouse HD and WT microglia and astrocytes. Moreover, in primary monocytes from HD patients and healthy subjects, NRF2 induction repressed expression of the proinflammatory cytokines IL-1, IL-6, IL-8, and TNFα. Together, our results demonstrate a multifaceted protective potential of NRF2 signaling in key cell types relevant to HD pathology.