MPTP Mouse Research Articles

Foliglurax, a positive allosteric modulator of the metabotrophic glutamate receptor 4, protects dopaminergic neurons in MPTP-lesioned male mice

Overactivity of the corticostriatal glutamatergic pathway is documented in Parkinson's disease (PD) and stimulation of presynaptic metabotropic glutamate (mGlu) receptors 4 on these striatal afferents inhibits glutamate release normalizing neuronal activity in the basal ganglia. Moreover, mGlu4 receptors are also expressed in glial cells and are able to modulate glial function making this receptor a potential target for neuroprotection. Hence, we investigated whether foliglurax, a positive allosteric modulator of mGlu4 receptors with high brain exposure after oral administration, has neuroprotective effects in MPTP mice to model early PD. Male mice were treated daily from day 1 to 10 with 1, 3 or 10 mg/kg of foliglurax and administered MPTP on the 5th day then euthanized on the 11th day. Dopamine neuron integrity was assessed with measures of striatal dopamine and its metabolites levels, striatal and nigral dopamine transporter (DAT) binding and inflammation with markers of striatal astrocytes (GFAP) and microglia (Iba1). MPTP lesion produced a decrease in dopamine, its metabolites and striatal DAT specific binding that was prevented by treatment with 3 mg/kg of foliglurax, whereas 1 and 10 mg/kg had no beneficial effect. MPTP mice had increased levels of GFAP; foliglurax treatment (3 mg/kg) prevented this increase. Iba1 levels were unchanged in MPTP mice compared to control mice. There was a negative correlation between dopamine content and GFAP levels. Our results show that positive allosteric modulation of mGlu4 receptors with foliglurax provided neuroprotective effects in the MPTP mouse model of PD.

Protection and Repair of the Nigrostriatal Pathway with Stem-Cell-Derived Carotid Body Glomus Cell Transplants in Chronic MPTP Parkinsonian Model.

Antiparkinsonian carotid body (CB) cell therapy has been proven to be effective in rodent and nonhuman primate models of Parkinson's disease (PD), exerting trophic protection and restoration of the dopaminergic nigrostriatal pathway. These neurotrophic actions are mediated through the release of high levels of glial-cell-line-derived neurotrophic factor (GDNF) by the CB transplant. Pilot clinical trials have also shown that CB autotransplantation can improve motor symptoms in PD patients, although its effectiveness is affected by the scarcity of the grafted tissue. Here, we analyzed the antiparkinsonian efficacy of in vitro-expanded CB dopaminergic glomus cells. Intrastriatal xenografts of rat CB neurospheres were shown to protect nigral neurons from degeneration in a chronic MPTP mouse PD model. In addition, grafts performed at the end of the neurotoxic treatment resulted in the repair of striatal dopaminergic terminals through axonal sprouting. Interestingly, both neuroprotective and reparative effects induced by in vitro-expanded CB cells were similar to those previously reported by the use of CB transplants. This action could be explained because stem-cell-derived CB neurospheres produce similar amounts of GDNF compared to native CB tissue. This study provides the first evidence that in vitro-expanded CB cells could be a clinical option for cell therapy in PD.

Microglial cGAS drives neuroinflammation in the MPTP mouse models of Parkinson's disease.

Neuroinflammation has been widely accepted as a cause of the degenerative process. Increasing interest has been devoted to developing intervening therapeutics for preventing neuroinflammation in Parkinson's disease (PD). It is well known that virus infections, including DNA viruses, are associated with an increased risk of PD. In addition, damaged or dying dopaminergic neurons can release dsDNA during PD progression. However, the role of cGAS, a cytosolic dsDNA sensor, in PD progression remains unclear. Adult male wild-type mice and age-matched male cGAS knockout (cGas-/- ) mice were treated with MPTP to induce neurotoxic PD model, and then behavioral tests, immunohistochemistry, and ELISA were conducted to compare disease phenotype. Chimeric mice were reconstituted to explore the effects of cGAS deficiency in peripheral immune cells or CNS resident cells on MPTP-induced toxicity. RNA sequencing was used to dissect the mechanistic role of microglial cGAS in MPTP-induced toxicity. cGAS inhibitor administration was conducted to study whether GAS may serve as a therapeutic target. We observed that the cGAS-STING pathway was activated during neuroinflammation in MPTP mouse models of PD. cGAS deficiency in microglia, but not peripheral immune cells, controlled neuroinflammation and neurotoxicity induced by MPTP. Mechanistically, microglial cGAS ablation alleviated the neuronal dysfunction and inflammatory response in astrocytes and microglia by inhibiting antiviral inflammatory signaling. Additionally, the administration of cGAS inhibitors conferred the mice neuroprotection during MPTP exposure. Collectively, these findings demonstrate microglial cGAS promote neuroinflammation and neurodegeneration during the progression of MPTP-induced PD mouse models and suggest cGAS may serve as a therapeutic target for PD patients. Although we demonstrated that cGAS promotes the progression of MPTP-induced PD, this study has limitations. We identified that cGAS in microglia accelerate disease progression of PD by using bone marrow chimeric experiments and analyzing cGAS expression in CNS cells, but evidence would be more straightforward if conditional knockout mice were used. This study contributed to the knowledge of the role of the cGAS pathway in PD pathogenesis; nevertheless, trying more PD animal models in the future will help us to understand the disease progression deeper and explore possible treatments.

The Effect of Aqueous Extract of Rosemary )Rosmarinus officinalis) on Parkinson's Disease Induced by MPTP in Male Mice (Original Article)

The Effect of Aqueous Extract of Rosemary )Rosmarinus officinalis) on Parkinson's Disease Induced by MPTP in Male Mice (Original Article)

Impeding the combination of astrocytic ASCT2 and NLRP3 by talniflumate alleviates neuroinflammation in experimental models of Parkinson's disease.

Alanine-serine-cysteine transporter 2 (ASCT2) is reported to participate in the progression of tumors and metabolic diseases. It is also considered to play a crucial role in the glutamate-glutamine shuttle of neuroglial network. However, it remains unclear the involvement of ASCT2 in neurological diseases such as Parkinson's disease (PD). In this study, we demonstrated that high expression of ASCT2 in the plasma samples of PD patients and the midbrain of MPTP mouse models is positively correlated with dyskinesia. We further illustrated that ASCT2 expressed in astrocytes rather than neurons significantly upregulated in response to either MPP+ or LPS/ATP challenge. Genetic ablation of astrocytic ASCT2 alleviated the neuroinflammation and rescued dopaminergic (DA) neuron damage in PD models invitro and invivo. Notably, the binding of ASCT2 to NLRP3 aggravates astrocytic inflammasome-triggered neuroinflammation. Then a panel of 2513 FDA-approved drugs were performed via virtual molecular screening based on the target ASCT2 and we succeed in getting the drug talniflumate. It is validated talniflumate impedes astrocytic inflammation and prevents degeneration of DA neurons in PD models. Collectively, these findings reveal the role of astrocytic ASCT2 in the pathogenesis of PD, broaden the therapeutic strategy and provide a promising candidate drug for PD treatment.

Artemisinin exerts a protective effect in the MPTP mouse model of Parkinson's disease by inhibiting microglial activation via the TLR4/Myd88/NF-KB pathway.

We performed cell and animal experiments to explore the therapeutic effect of artemisinin on Parkinson's disease (PD) and the TLR4/Myd88 signaling pathway. C57 mice were randomly divided into the blank, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced and artemisinin-treated groups. Clinical symptoms, the number of dopaminergic (DAergic) neurons in the substantia nigra, and microglial cell activation were compared among the three groups. Subsequently, BV-2 cell activation and TLR4/Myd88 pathway component expression were compared among the blank, MPP+ -treated, artemisinin-treated, and TLR4 activator-treated groups. Behavioral symptoms were improved, the number of DAergic neurons in the substantia nigra of the midbrain was increased, and microglial cell activation was decreased in artemisinin-treated MPTP-induced PD model mice compared with control-treated MPTP-induced PD model mice (p < 0.05). The cell experiments revealed that artemisinin treatment reduced MPP+ -induced BV-2 cell activation and inhibited the TLR4/Myd88 signaling pathway. Moreover, the effect of artemisinin on the BV-2 cell model was inhibited by the TLR4 activator LPS (p < 0.05). Artemisinin may reduce damage to DAergic neurons in a PD mouse model by decreasing microglial activation through the TLR4-mediated MyD88-dependent signaling pathway. However, this finding cannot explain the relationship between microglia and DAergic neurons.

Intermittent fasting protects the nigral dopaminergic neurons from MPTP-mediated dopaminergic neuronal injury in mice

Dietary restriction through low-calorie intake or intermittent fasting benefits many organs, including the brain. This study investigated the neuroprotective effects of fasting in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson's disease. We found that fasting every other day rather than weekly increased the levels of brain-derived neurotrophic factor and glial-derived neurotrophic factor in the nigrostriatal pathway. Therefore, we maintained the animals on alternate-day fasting for 2 weeks and injected MPTP (30 mg/kg/day, intraperitoneally [i.p.]) for five days. We observed that alternate-day fasting attenuated MPTP-induced dopaminergic neuronal loss and astroglial activation in the substantia nigra and the striatum. Moreover, neurochemical analysis using high-performance liquid chromatography showed that alternate-day fasting reduced MPTP-induced depletion of striatal dopamine. Consistent with these results, behavioral tests showed that fasting suppressed the motor impairment caused by MPTP. Furthermore, fasting increased the phosphorylation of phosphatidylinositol-3-kinase and protein kinase B, which are downstream signaling molecules of neurotrophic factors. Fasting also increased the phosphorylation of extracellular signal-regulated protein kinase and cAMP response element-binding protein, further supporting the involvement of neurotrophic factors in the observed neuroprotective effects. Hence, our results demonstrated the dopaminergic neuroprotection of intermittent fasting in an MPTP mouse model of Parkinson's disease, supporting the idea that fasting could be an instrumental tool for preventing neurodegeneration in the brain.

Neurochemical, histological, and behavioral profiling of the acute, sub-acute, and chronic MPTP mouse model of Parkinson's disease.

Parkinson's disease (PD) is a heterogeneous multi-systemic disorder unique to humans characterized by motor and non-motor symptoms. Preclinical experimental models of PD present limitations and inconsistent neurochemical, histological, and behavioral readouts. The 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD is the most common in vivo screening platform for novel drug therapies; nonetheless, behavioral endpoints yielded amongst laboratories are often discordant and inconclusive. In this study, we characterized neurochemically, histologically, and behaviorally three different MPTP mouse models of PD to identify translational traits reminiscent of PD symptomatology. MPTP was intraperitoneally (i.p.) administered in three different regimens: (i) acute-four injections of 20 mg/kg of MPTP every 2 h; (ii) sub-acute-one daily injection of 30 mg/kg of MPTP for 5 consecutive days; and (iii) chronic-one daily injection of 4 mg/kg of MPTP for 28 consecutive days. A series of behavioral tests were conducted to assess motor and non-motor behavioral changes including anxiety, endurance, gait, motor deficits, cognitive impairment, circadian rhythm and food consumption. Impairments in balance and gait were confirmed in the chronic and acute models, respectively, with the latter showing significant correlation with lesion size. The sub-acute model, by contrast, presented with generalized hyperactivity. Both, motor and non-motor changes were identified in the acute and sub-acute regime where habituation to a novel environment was significantly reduced. Moreover, we report increased water and food intake across all three models. Overall, the acute model displayed the most severe lesion size, while across the three modelsstriatal dopamine content (DA) did not correlate with the behavioral performance. The present study demonstrates that detection of behavioral changes following MPTP exposure is challenging and does not correlate with the dopaminergic lesion extent.

A novel small positive allosteric modulator of neuropeptide receptor PAC1-R exerts neuroprotective effects in MPTP mouse Parkinson's disease model.

As a neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP)-preferring receptor, PAC1-R mediates effective neuroprotective activity. Based on the finding that the antibiotic doxycycline (DOX) with clinical neuroprotective activity functions as a positive allosteric modulator (PAM) of neuropeptide PACAP receptor 1 (PAC1-R), we use virtual and laboratory screening to search for novel small molecule PAMs of PAC1-R. Virtual screening is carried out using a small-molecule library TargetMol. After two-level precision screening with Glide, the top five compounds with the best predicted affinities for PAC1-R are selected and named small positive allosteric modulator 1‒5 (SPAM1‒5). Our results show that only 4-{[4-(4-Oxo-3,4-2-yl)butanamido]methyl}benzoic acid (SPAM1) has stronger neuroprotective activity than DOX in the MPP+ PD cell model and MPTP PD mouse model. SPAM1 has a higher affinity for PAC1-R than DOX, but has no antibiotic activity. Moreover, both SPAM1 and DOX block the decrease of PAC1-R level in mouse brain tissues induced by MPTP. The successful screening of SPAM1 offers a novel drug for the treatment of neurodegenerative disease targeting the PAC1-R.

Characterization of Nasco grape pomace-loaded nutriosomes and their neuroprotective effects in the MPTP mouse model of Parkinson's disease.

Grape pomaces have recently received great attention for their richness in polyphenols, compounds known to exert anti-inflammatory and antioxidant effects. These pomaces, however, have low brain bioavailability when administered orally due to their extensive degradation in the gastrointestinal tract. To overcome this problem, Nasco pomace extract was incorporated into a novel nanovesicle system called nutriosomes, composed of phospholipids (S75) and water-soluble maltodextrin (Nutriose® FM06). Nutriosomes were small, homogeneously dispersed, had negative zeta potential, and were biocompatible with intestinal epithelial cells (Caco-2). Nasco pomace extract resulted rich in antioxidant polyphenols (gallic acid, catechin, epicatechin, procyanidin B2, and quercetin). To investigate the neuroprotective effect of Nasco pomace in the subacute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson’s disease (PD), Nasco nutriosomes or Nasco suspension was administered intragastrically and their neuroprotective effects were evaluated. Degeneration of nigro-striatal dopaminergic neurons induced by subacute MPTP treatment, the pathological hallmark of PD, was assessed through immunohistochemical evaluation of tyrosine hydroxylase (TH) in the caudate-putamen (CPu) and substantia nigra pars compacta (SNc), and the dopamine transporter (DAT) in CPu. Immunohistochemical analysis revealed that Nasco nutriosomes significantly prevented the reduction in TH- and DAT-positive fibres in CPu, and the number of TH-positive cells in SNc following subacute MPTP treatment, while Nasco suspension counteracted MPTP toxicity exclusively in SNc. Overall, these results highlight the therapeutic effects of Nasco pomace extract when administered in a nutriosome formulation in the subacute MPTP mouse model of PD and validate the effectiveness of the nutriosome preparation over suspension as an innovative nano-drug delivery system for in vivo administration.

Microglial AIM2 alleviates antiviral-related neuro-inflammation in mouse models of Parkinson's disease.

Inflammasome involvement in Parkinson's disease (PD) has been intensively investigated. Absent in melanoma 2 (AIM2) is an essential inflammasome protein known to contribute to the development of several neurological diseases. However, a specific role for AIM2 in PD has not been reported. In this study, we investigated the effect of AIM2 in the N-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced PD model by use of various knockout and bone marrow chimeric mice. The mechanism of action for AIM2 in PD was assessed by RNA-sequencing and in vitro primary microglial transfection. Results were validated in the A30P transgenic mouse model of PD. In the MPTP mouse model, AIM2 activation was found to negatively regulate neuro-inflammation independent of the inflammasome. Microglial AIM2 deficiency exacerbated behavioral and pathological features of both MPTP-induced and transgenic PD mouse models. Mechanistically, AIM2 reduced cyclic GMP-AMP synthase (cGAS)-mediated antiviral-related inflammation by inhibition of AKT-interferon regulatory factor 3 (IRF3) phosphorylation. These results demonstrate microglial AIM2 to inhibit the antiviral-related neuro-inflammation associated with PD and provide for a foundation upon which to identify new therapeutic targets for treatment of the disease.

Beneficial effect of transient desflurane inhalation on relieving inflammation and reducing signaling induced by MPTP in mice.

ObjectiveTo determine if the beneficial effects of transient desflurane application mitigates inflammation and decrease associated signaling induced by 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) in mice.MethodsMice were induced to develop Parkinson’s disease (PD) by intraperitoneal injection with MPTP for 20 consecutive days, and validated mice were randomly allocated to four groups. Collected samples from euthanized mice were designated for the following analyses: 1) immunohistochemical staining for positive dopaminergic neurons in the substantia nigra and striatum, 2) immunofluorescence staining for ionized calcium binding adaptor molecule-1 (Iba1) and glial fibrillary acid protein (GFAP), and 3) western blotting for p38, p-p38, toll-like receptor 4, and tumor necrosis factor (TNF)-α.ResultsThe inhalation of desflurane for 1 hour ameliorated locomotory dysfunctions of PD mice by recovering the loss of Iba1- and GFAP-positive dopaminergic neurons, deactivating microglial cells and astrocytes, and decreasing the amounts of inflammatory cytokines (TNF-α).ConclusionsThese findings suggest that transient desflurane inhalation may provide some benefits for PD through ameliorating inflammation and enhancing locomotor activity.

Peripheral Neuroprotective and Immunomodulatory Effects of 5α-Reductase Inhibitors in Parkinson's Disease Models.

Gastrointestinal disorders in Parkinson’s disease (PD) have been associated with neuronal alteration in the plexus of the gut. We previously demonstrated the immunomodulatory effect of female hormones to treat enteric neurodegeneration in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. This study made the hypothesis of obtaining similar neuroprotection as with hormone treatments by affecting steroidogenesis with two 5α-reductase inhibitors, finasteride and dutasteride. These drugs are approved to treat benign prostatic hyperplasia and alopecia and display mitochondrial effects. In MPTP-treated mice, the dopaminergic and vasoactive intestinal peptide (VIP) neurons alteration was prevented by finasteride and dutasteride, while the increase in proinflammatory macrophages density was inhibited by dutasteride treatment but not finasteride. NF-κB response, oxidative stress, and nitric oxide and proinflammatory cytokines production in vitro were only prevented by dutasteride. In addition, mitochondrial production of free radicals, membrane depolarization, decreased basal respiration, and ATP production were inhibited by dutasteride, while finasteride had no effect. In conclusion, the present results indicate that dutasteride treatment prevents enteric neuronal damages in the MPTP mouse model, at least in part through anti-inflammatory and mitochondrial effects. This suggests that drug repurposing of dutasteride might be a promising avenue to treat enteric neuroinflammation in early PD.

N-cystaminylbiguanide MC001 prevents neuron cell death and alleviates motor deficits in the MPTP-model of Parkinson’s disease

Parkinson’s disease (PD) is a common neurodegenerative disease characterized by the progressive loss of dopaminergic (DA) neurons in the substantia nigra (SN), which is highly associated with oxidative stress. Antioxidants are therefore considered as potential therapies in PD treatment. In this study, we examined the neuroprotective effect of a cysteamine-based biguanide N-cystaminylbiguanide (MC001) in the MPTP mouse model of PD. The results showed that MC001 prevented neuron cell death and alleviated motor deficits in the MPTP mouse model of PD. Both in vitro and in vivo data indicated that MC001 may exert its neuroprotective effect by alleviating ROS production, suppressing neuroinflammation, and upregulating BDNF expression. Further mechanistic studies revealed that MC001 promoted GSH synthesis by inducing the expression of Glutamate-cysteine ligase catalytic subunit (Gclc) and enhancing the activity of Glutamate-cysteine ligase (Gcl). Our results suggest that MC001 warrants further investigation as a potential candidate for the treatment of PD.

Garcinia morella extract confers dopaminergic neuroprotection by mitigating mitochondrial dysfunctions and inflammation in mouse model of Parkinson's disease.

Dopaminergic neuroprotection is the main interest in designing novel therapeutics against Parkinson's disease (PD). In the process of dopaminergic degeneration, mitochondrial dysfunctions and inflammation are significant. While the existing drugs provide symptomatic relief against PD, a therapy conferring total neuroprotection by targeting multiple degenerative pathways is still lacking. Garcinia morella is a common constituent of Ayurvedic medication and has been used for the treatment of inflammatory disorders. The present study investigates whether administration of G. morella fruit extract (GME) in MPTP mouse model of PD protects against dopaminergic neurodegeneration, including the underlying pathophysiologies, and reverses the motor behavioural abnormalities. Administration of GME prevented the loss of dopaminergic cell bodies in the substantia nigra and its terminals in the corpus striatum of PD mice. Subsequently, reversal of parkinsonian behavioural abnormalities, viz. akinesia, catalepsy, and rearing, was observed along with the recovery of striatal dopamine and its metabolites in the experimental model. Furthermore, reduced activity of the mitochondrial complex II in the nigrostriatal pathway of brainof the mice was restored after the administration of GME. Also, MPTP-induced enhanced activation of Glial fibrillary acidic protein (GFAP) and neuronal nitric oxide synthase (nNOS) in the nigrostriatal pathway, which are the markers of inflammatory stress, were found to be ameliorated on GME treatment. Thus, our study presented a novel mode of dopaminergic neuroprotection by G. morella in PD by targeting the mitochondrial dysfunctions and neuroinflammation, which are considered to be intricately associated with the loss of dopaminergic neurons.

CREB Inactivation by HDAC1/PP1γ Contributes to Dopaminergic Neurodegeneration in Parkinson's Disease.

Understanding the pathogenesis of nigral dopaminergic neurodegeneration is critical for developing mechanism-based treatments for Parkinson's disease (PD). In the nigral dopaminergic neurons of postmortem human PD brains, we found that CREB, a well-recognized pro-survival transcription factor in neurons, was inactivated by dephosphorylation at Ser133. CREB dephosphorylation correlated with decreased expression of NURR1, one of its target genes crucial for dopaminergic neuron survival, confirming that CREB function was impaired in nigral dopaminergic neurons in PD. An MPTP mouse model was used to further elucidate the mechanism underlying CREB dephosphorylation. Protein phosphatase 1γ (PP1γ), which dephosphorylates CREB, was constitutively associated with histone deacetylase 1 (HDAC1). HDAC1 promotes CREB Ser133 dephosphorylation via a stable interaction with PP1γ. We found that CREB interacted with the HDAC1/PP1γ complex during dopaminergic neurodegeneration. Importantly, increased CREB/HDAC1 interaction occurred in the nigral dopaminergic neurons of PD patients as demonstrated using a proximity ligation assay. Disrupting CREB/HDAC1 interaction via either overexpression of GAL4 M1, a CREB mutant, or administration of trichostatin A, a pan-HDAC inhibitor, restored the expression levels of phospho-CREB (Ser133) and NURR1, and protected nigral dopaminergic neurons in the MPTP-treated mouse brain. Collectively, our results demonstrated that HDAC1/PP1γ-mediated CREB inactivation contributed to dopaminergic neuronal degeneration. Disruption of CREB/HDAC1 interaction has the potential to be a new approach for PD therapy.SIGNIFICANCE STATEMENT Parkinson's disease (PD) is the most common movement disorder attributed to the progressive loss of dopaminergic neurons in the substantia nigra. Understanding the pathogenesis of nigral dopaminergic neurodegeneration is critical for developing mechanism-based treatments for PD. We found in nigral dopaminergic neurons of postmortem human PD brains that CREB, a well-recognized pro-survival transcription factor in neurons, was inactivated by dephosphorylation at Ser133. HDAC1, constitutively associated with PP1γ, interacted with CREB to mediate its dephosphorylation during dopaminergic neurodegeneration. Disrupting CREB/HDAC1 interaction restored CREB activity and protected nigral dopaminergic neurons in the MPTP mouse brains. This work suggests that disruption of the CREB/HDAC1 interaction to restore CREB activity may be a potential therapeutic approach in PD.

P 12 Expansion of regulatory T cells by early CD28 Superagonist treatment attenuates neurodegeneration in MPTP mice

Introduction: The neuropathology induced by injection of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a commonly used and well characterized animal model of Parkinson's disease (PD). It shows pathophysiological hallmarks of PD such as the loss of dopaminergic neurons from the substantia nigra (SN) as well as neuroinflammation. Expansion of CD4 + Foxp3 + regulatory T cells (Tregs) by administration of a single dose of a CD28 Superagonist monoclonal antibody (CD28-SA) in the MPTP mouse model was evaluated as a potential anti-inflammatory therapy for PD. Materials and Methods: An acute PD-like disease was induced in mice by a regimen of four intraperitoneal injections at 2 h intervals of MPTP-HCl (20 mg MPTP/kg bodyweight in NaCl). The same injection intervals were used for saline injected control animals (ctrl). The CD28-SA (clone D665, in PBS) or vehicle (PBS) was subcutaneously injected at an early (three days before MPTP intoxication) or late time point (30 minutes after the last MPTP injection). The total number of Nissl + neurons and dopaminergic neurons (TH + ) of the SN were analysed by unbiased stereology seven days after MPTP intoxication. Two groups (MPTP + vehicle; MPTP + CD28-SA) were compared for the early treatment time point and four groups (ctrl + vehicle; ctrl + CD28-SA; MPTP + vehicle; MPTP + CD28-SA) for the late treatment time point. Results: At the late treatment time point significantly decreased total cell numbers of TH + and Nissl + neurons were observed in MPTP mice treated with vehicle compared to ctrl + vehicle and ctrl + CD28-SA mice (TH + neurons: ctrl + vehicle: 7840 ± 405; ctrl + CD28-SA: 8422 ± 286; MPTP + vehicle: 5289 ± 230 / Nissl + neurons: ctrl + vehicle: 18949 ± 309; ctrl + CD28-SA: 19490 ± 212; MPTP + vehicle: 14921 ± 783). CD28-SA treatment of MPTP mice did not rescue TH + and Nissl + neurons within the SN (TH + neurons: MPTP + D665: 5933 ± 462 / Nissl + neurons: MPTP + CD28-SA: 15523 ± 754). In contrast, early treatment of MPTP mice with the CD28-SA led to higher numbers of both TH + and Nissl + neurons compared to vehicle injected mice (TH + neurons: MPTP + CD28-SA: 5645 ± 313; MPTP + vehicle: 4912 ± 171 / Nissl + neurons: MPTP + CD28-SA: 13171 ± 574; MPTP + vehicle: 11062 ± 497). Discussion/Conclusion: Our delayed-start design study demonstrates a neuroprotective effect of early CD28-SA-induced CD4 + Foxp3 + Treg expansion within the SN in the MPTP mouse model of PD.

Neuronal SH2B1 attenuates apoptosis in an MPTP mouse model of Parkinson's disease via promoting PLIN4 degradation

The incidence of Parkinson's disease (PD) has increased tremendously, especially in the aged population and people with metabolic dysfunction; however, its underlying molecular mechanisms remain unclear. SH2B1, an intracellular adaptor protein, contributes to the signal transduction of several receptor tyrosine kinases and exerts beneficial metabolic effects for body weight regulation; however, whether SH2B1 plays a major role in pathological neurodegeneration in PD has not yet been investigated. This study aimed to investigate the effects of SH2B1 in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)–induced PD mice with Sh2b1 deficiency or neuron-specific Sh2b1 overexpression. Cellular and molecular mechanisms were elucidated using human dopaminergic neuron SH-SY5Y cells analysed. We found that SH2B1 expression was confirmed to be downregulated in the blood samples of PD patients and in the brains of mice with MPTP-induced chronic PD. Sh2b1 deficiency caused marked exacerbation of behavioural defects and increased neuronal apoptosis in MPTP-treated mice, whereas restoration of neuron-specific Sh2b1 expression significantly reversed these effects. Similar results were observed in MPP + -treated SH-SY5Y cells. Mechanistically, upon binding to heat shock cognate 70 (HSC70), SH2B1 promotes HSC70-related recognition and PLIN4 lysosomal translocation and degradation, thus suppressing lipid peroxidation stress in the brains of PD mice. Adeno-associated virus-mediated rescue of neuronal HSC70 expression functionally alleviated the neuropathology of PD in wild-type but not in Sh2b1-deficient mice. This is the first study to examine the molecular underpinnings of SH2B1 against MPTP-induced neurodegeneration through cell autonomous promotion of neuronal survival in an in vivo PD model. Our findings reveal that SH2B1 antagonizes neurodegenerative pathology in PD via the SH2B1–HSC70–PLIN4 axis.

Programmed Death-1 Deficiency Aggravates Motor Dysfunction in MPTP Model of Parkinson's Disease by Inducing Microglial Activation and Neuroinflammation in Mice.

Abundant reactive gliosis and neuroinflammation are typical pathogenetic hallmarks of brains in Parkinson's disease (PD) patients, but regulation mechanisms are poorly understood. We are interested in role of programmed death-1 (PD-1) in glial reaction, neuroinflammation and neuronal injury in PD pathogenesis. Using PD mouse model and PD-1 knockout (KO) mice, we designed wild-type-control (WT-CON), WT-1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (WT-MPTP), PD-1-KO-control (KO-CON) and PD-1-KO-MPTP (KO-MPTP), and observed motor dysfunction of animal, morphological distribution of PD-1-positive cells, dopaminergic neuronal injury, glial activation and generation of inflammatory cytokines in midbrains by motor behavior detection, immunohistochemistry and western blot. WT-MPTP mouse model exhibited decrease of PD-1/Iba1-positive microglial cells in the substantia nigra compared with WT-CON mice. By comparison of four groups, PD-1 deficiency showed exacerbation in motor dysfunction of animals, decreased expression of TH protein and TH-positive neuronal protrusions. PD-1 deficiency enhanced microglial activation, production of proinflammatory cytokines like inducible nitric oxide synthase, tumor necrosis factor-α, interleukin-1β and interleukin-6, and expression and phosphorylation of AKT and ERK1/2 in the substantia nigra of MPTP model. We concluded that PD-1 deficiency could aggravate motor dysfunction of MPTP mouse model by inducing microglial activation and neuroinflammation in midbrains, suggesting that PD-1 signaling abnormality might be possibly involved in PD pathogenesis.

Tetramethyl pyrazine exerts anti-apoptotic and antioxidant effects in a mouse model of MPTP-induced Parkinson's disease via regulation of the expressions of Bax, Bcl-2, Nrf2 and GCLC

&#x0D; &#x0D; &#x0D; &#x0D; Purpose: To investigate the effect of tetramethyl pyrazine (TMP) on MPTP)-mediated neuronal apoptosis and oxidative imbalance in mice, and the mechanism of action involved.&#x0D; Methods: Forty-five mice were assigned evenly to blank control, MPTP and TMP groups. The protein concentrations of Bax, Bcl-2, cytochrome C (Cyt c), Nrf2, GCLC and cleaved caspase-3; and levels of glutathione (GSH) and thiobarbituric acid reactive products (TBARS) were evaluated and compared amongst the groups.&#x0D; Results: Cyt c, Bax, and cleaved caspase-3 protein levels in TMP group were significantly lower than those in MPTP group, while Bcl-2 protein expression was higher in TMP group than in MPTP mice (p &lt; 0.05). Furthermore, TBARS was lower in TMP group than in MPTP group, while GSH level increased, relative to MPTP mice. The levels of Nrf2 and GCLC were significantly higher in TMP group than in MPTP group (p &lt; 0.05).&#x0D; Conclusion: Tetramethyl pyrazine exerts anti-apoptotic and antioxidant effects on MPTP-mediated Parkinsonism via regulation of the expressions of Bax, Bcl-2, Nrf2 and glutamate-cysteine ligase catalytic subunit. Thus, TMP has potential for use in the treatment Parkinson’s disease.&#x0D; &#x0D; &#x0D; &#x0D;