Chronic behavioral stress exaggerates motor deficit and neuroinflammation in the MPTP mouse model of Parkinson's disease.
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ABSTRACT:
SUBMITTER: Lauretti E
PROVIDER: S-EPMC4872430 | biostudies-other | 2016 Feb
REPOSITORIES: biostudies-other
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Project description: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 models striatal 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.
| S-EPMC10098710 | biostudies-literature
Project description:Parkinson´s disease is the most important neuromotor pathology due to the prominent loss of dopaminergic neurons in the substantia nigra pars compacta. There is an inherent deficiency of dopamine in Parkinson´s disease, which is aggravated when neuroinflammatory processes are present. Several biomolecules are interesting candidates for the regulation of inflammation and possible neuroprotection, such as valerenic acid, one of the main components of Valeriana officinalis. A 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP)-induced mouse model of Parkinson's disease was developed to evaluate the motor effects of valerenic acid. The evaluation was carried out with four tests (an invert screen test for muscle strength, cross beam test, open field mobility test and lifting on hind legs test). Subsequently, the neuroinflammatory process was evaluated through ELISA of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α and IFN-γ). The decreases in the inflammatory and neurodegenerative processes were evaluated by Western blot and immunohistochemistry analyses of the tissues, which included an evaluation of the tyrosine hydroxylase and GFAP proteins. Finally, the predicted mechanism of action of valerenic acid was supported by molecular docking calculations with the 5-HT5A receptor. The results indicate that the use of valerenic acid as a co-treatment decreases the neuroinflammation in Parkinson's disease induced by MPTP and provides evidence of a decrease in the evaluated pro-inflammatory cytokines and in the amount of GFAP in the mesencephalic area. Valerenic acid prevents neuroinflammation in a Parkinson's disease mouse model, which might reflect the neuroprotection of dopaminergic neurons with the recovery of motor ability.
| S-EPMC6938966 | biostudies-literature
Project description:BackgroundNeuroinflammation 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.MethodsAdult 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.ResultsWe 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.ConclusionsCollectively, 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.Limitations of the studyAlthough 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.
| S-EPMC10324349 | biostudies-literature
Project description:Parkinson's disease (PD) is a neurodegenerative disease characterized by the loss of dopaminergic neurons in the substantia nigra and diminished dopamine content in the striatum. Recent reports show that 7,8-dihydroxyflavone (DHF), a TrkB agonist, attenuates the α-synuclein deposition and ameliorates motor deficits. However, the underlying mechanism is unclear. In this study, we investigated whether autophagy is involved in the clearance of α-synuclein and the signaling pathway through which DHF exerts therapeutic effects. We found that the administration of DHF (5 mg/kg/day, i.p.) prevented the loss of dopaminergic neurons and improved motor functions in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD, whereas these protective effects of DHF were completely blocked by autophagy inhibitor chloroquine (CQ). Further in vitro studies showed that autophagy was inhibited in N2A cells treated with 1-methyl-4-phenylpyridinium (MPP+), as reflected by a significant decrease in the expressions of autophagy marker proteins (Beclin1 and LC3II) and an increase in the expression of autophagic flux marker p62. DHF restored the impaired autophagy to control level in MPP+-treated N2A cells by inhibiting the ERK-LKB1-AMPK signaling pathway. Taken together, these results demonstrate that DHF exerts therapeutic effects in MPTP/MPP+-induced neurotoxicity by inhibiting the ERK-LKB1-AMPK signaling pathway and subsequently improving impaired autophagy.
| S-EPMC8452727 | biostudies-literature
Project description:Parkinsonian patients experience not only the physical discomfort of motor disorders but also the considerable psychological distress caused by cognitive deficits and behavioral disorders. These two factors can result in a disruption of social relationships during the symptomatic and even the presymptomatic motor states of the disease. However, it remains difficult, if not impossible, to evaluate social relationships in presymptomatic patients. The present study focused on the evaluation of social relationships within a group of female long-tailed macaques during presymptomatic and symptomatic motor states induced by Chronic Low-Dose (CLD) and then Chronic High-Dose (CHD) systemic administration of 1-methyl-4-phenyl-l,2,3,6-tetrahydropyridine (MPTP). Dopaminergic denervation within basal ganglia and cortical areas was evaluated using Positron Emission Tomography (PET) scans with (18)F-DOPA (6-[18F]-fluoro-L-3,4-dihydroxyphenylalanine) radiotracer. Interestingly, social behavioral changes could be identified in the presymptomatic motor state before any motor and/or cognitive impairment occurred. Stronger effects were observed in subordinate animals compared to dominant animals. From baseline state to CLD-presymptomatic motor state, the frequency of emitted affiliative and aggressive behaviors increased. From CLD-presymptomatic to CHD-presymptomatic motor states, the frequency of the three categories of social behaviors (aggressive, submissive and affiliative) decreased. At this time, quantitative data analysis in PET scans highlighted a dopaminergic denervation in the insula and the posterior caudate nucleus. Finally, the frequency of the three categories of social behaviors decreased during the stable-symptomatic motor state compared to baseline and presymptomatic motor states; this was also associated with motor and cognitive disorders and a dopaminergic denervation in all the evaluated cortical and subcortical structures.
| S-EPMC4341564 | biostudies-literature
Project description:Accumulating evidences suggest that neuroinflammation is a pathological hallmark of Parkinson's disease (PD), a neurodegenerative disorder characterized by loss of dopaminergic neurons in substantia nigra pars compacta (SNpc). MicroRNAs have been recently recognized as crucial regulators of inflammatory responses. Here, we found significant downregulation of microRNA-30e (miR-30e) in SNpc of MPTP-induced PD mice. Next, we employed miR-30e agomir to upregulate miR-30e expression in MPTP-treated mice. Our results showed that delivery of miR-30e agomir remarkably improved motor behavioral deficits and neuronal activity, and inhibited the loss of dopamine neurons. Moreover, the increased α-synuclein protein expression in SNpc of MPTP-PD mice was alleviated by the upregulation of miR-30e. Further, miR-30e agomir administration also attenuated the marked increase of inflammatory cytokines, such as TNF-α, COX-2, iNOS, and restored the decreased secretion of BDNF in SNpc. In addition, we demonstrated for the first time that miR-30e directly targeted to Nlrp3, thus suppressing Nlrp3 mRNA and protein expression. Finally, miR-30e upregulation significantly inhibited the activation of Nlrp3 inflammasome as evident from the decreased Nlrp3, Caspase-1 and ASC expressions and IL-18 and IL-1β secretions. Taken together, our study demonstrates that miR-30e ameliorates neuroinflammation in the MPTP model of PD by decreasing Nlrp3 inflammasome activity. These findings suggesting that miR30e may be a key inflammation-mediated molecule that could be a potential target for PD therapeutics.
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Project description:Background/aimsSince the degeneration of the nigrostriatal dopaminergic pathway in Parkinson's disease (PD) is associated with the inflammation process and decreased levels of cyclic nucleotides, inhibition of up-regulated cyclic nucleotide phosphodiesterases (PDEs) appears to be a promising therapeutic strategy. We used ibudilast (IBD), a non-selective PDE3,4,10,11 inhibitor, due to the abundant PDE 4 and 10 expression in the striatum. The present study for the first time examined the efficacy of IBD in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD.MethodsIBD [0, 20, 30, 40, or 50 mg/kg] was injected b.i.d. subcutaneously for nine days to three-month-old male C57Bl/10Tar mice, beginning two days prior to MPTP (60 mg/kg) intoxication. High-pressure liquid chromatography, Western blot analysis, and real time RT-PCR methods were applied.ResultsOur study demonstrated that chronic administration of IBD attenuated astroglial reactivity and increased glial cell-derived neurotrophic factor (GDNF) production in the striatum. Moreover, IBD reduced TNF-α, IL-6, and IL-1β expression.ConclusionIBD had a well-defined effect on astroglial activation in the mouse model of PD; however, there was no protective effect in the acute phase of injury. Diminished inflammation and an increased level of GDNF may provide a better outcome in the later stages of neurodegeneration.
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Project description:Restorative/protective therapies to restore dopamine neurons in the substantia nigra pars compacta (SNpc) are greatly needed to effectively change the debilitating course of Parkinson's disease. In this study, we tested the therapeutic potential of a neurogenic neurosteroid, allopregnanolone, in the restoration of the components of the nigrostriatal pathway in MPTP-lesioned mice by measuring striatal dopamine levels, total and tyrosine hydroxylase immunoreactive neuron numbers and BrdU-positive cells in the SNpc. An acute treatment (once/week for two weeks) with allopregnanolone restored the number of tyrosine hydroxylase-positive and total cell numbers in the SNpc of MPTP-lesioned mice, even though this did not increase striatal dopamine. It was also noted that MPTP treated mice to which allopregnanolone was administered had an increase in BrdU-positive cells in the SNpc. The effects of allopregnanolone in MPTP-lesioned mice were more apparent in mice that underwent behavioral tests. Interestingly, mice treated with allopregnanolone after MPTP lesion were able to perform at levels similar to that of non-lesioned control mice in a rotarod test. These data demonstrate that allopregnanolone promotes the restoration of tyrosine hydroxylase immunoreactive neurons and total cells in the nigrostriatal tract, improves the motor performance in MPTP-treated mice, and may serve as a therapeutic strategy for Parkinson's disease.
| S-EPMC3510204 | biostudies-literature
Project description:Increasing evidence suggests a pivotal role of receptor-interacting protein kinase 1 (RIPK1), an initiator of necroptosis, in neuroinflammation. However, the precise role of RIPK1 in microglial activation remains unclear. In the present study, we explored the role of RIPK1 in lipopolysaccharide (LPS)-induced neuroinflammation and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model mice by using RIPK1-specific inhibitors necrostatin-1 (Nec-1) and necrostatin-1 stable (Nec-1s). Nec-1/Nec-1s or RIPK1 siRNA inhibited the production of proinflammatory molecules and the phosphorylation of RIPK1-RIPK3-MLKL and cell death in LPS-induced inflammatory or LPS/QVD/BV6-induced necroptotic conditions of BV2 microglial cells. Detailed mechanistic studies showed that Nec-1/Nec-1s exerted anti-inflammatory effects by modulating AMPK, PI3K/Akt, MAPKs, and NF-κB signaling pathways in LPS-stimulated BV2 cells. Subsequent in vivo studies showed that Nec-1/Nec-1s inhibited microglial activation and proinflammatory gene expression by inhibiting the RIPK1 phosphorylation in the brains of LPS-injected mice. Furthermore, Nec-1/Nec-1s exert neuroprotective and anti-inflammatory effects in MPTP-induced PD mice. We found that p-RIPK1 is mainly expressed in microglia, and thus RIPK1 may contribute to neuroinflammation and subsequent cell death of dopaminergic neurons in MPTP-induced PD model mice. These data suggest that RIPK1 is a key regulator of microglial activation in LPS-induced neuroinflammation and MPTP-induced PD mice.
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Project description:Elevated ER stress has been linked to the pathogenesis of several disease conditions including neurodegeneration. In this study, we have holistically determined the differential expression of all the nuclear receptors (NRs) in the presence of classical ER stress inducers. Activation of Nr1h4 and Thrb by their cognate ligands (GW4064 and T3) ameliorates the tunicamycin (TM)-induced expression of ER stress genes. A combination of both ligands is effective in mitigating cell death induced by TM. Further exploration of their protective effects in the Parkinson's disease (PD) model shows that they reduce MPP+-induced dissipation of mitochondrial membrane potential and ROS generation in an in vitro PD model in neuronal cells. Furthermore, the generation of an experimental murine PD model reveals that simultaneous treatment of GW4064 and T3 protects mice from ER stress, dopaminergic cell death, and functional deficits in the MPTP mouse model of PD. Thus, activation of Nr1h4 and Thrb by their respective ligands plays an indispensable role in ER stress amelioration and mounts protective effects in the MPTP mouse model of PD.
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