Murine Model Of Parkinson's Disease Research Articles

The laterodorsal tegmental nucleus improves breathing and sleep in a Parkinson’s disease animal model

Parkinson's disease (PD) is a neurological disorder resulting from the degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc). PD is characterized by classical and non-classical symptoms including respiratory instability and sleep disturbances. An important region for the control of sleep and possibly respiration is the laterodorsal tegmental nucleus (LDTg), a nucleus composed of cholinergic, glutamatergic, and GABAergic neurons. We hypothesize that stimulation of cholinergic neurons in the LDTg can lead to improvements in sleep and respiratory disturbances in a murine model of PD. Adult mice (CEUA: 6641200919 and SCRI: 18819) that express the fluorescent green protein in cholinergic cells (Chat-cre, ai6) received bilateral injections of AAV-hM3Dq-mCherry or AAV-mCherry vectors into LDTg. After ten days, the animals received nigrostriatal injections of vehicle or 6-hydroxydopamine (6-OHDA, 10 μg/μl). Eight days later, we implanted EEG and EMG electrodes. In 6-OHDA-injected mice, there was a 79% and 29% reduction in the number of dopaminergic neurons in SNpc and cholinergic neurons in LDTg, respectively. This reduction was associated with an increase in the number of apneas and a 17% and 26% reduction in respiratory frequency during non-REM (NREMs) and REM (REMs) sleep, respectively. In the same animals, there was also a decrease in wakefulness time, and an increase in total sleep time. Selective pharmacogenetic stimulation of ChAT+ neurons of the LDTg rescued the respiratory frequency during REMs and reduced the number of apneas both in NREMs and REMs in 6-OHDA mice. These results demonstrate that in this PD model the LDTg plays a significant role in respiratory changes associated with sleep regulation. FAPESP, CAPES, CNPq and NIH. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Nr1h4 and Thrb ameliorate ER stress and provide protection in the MPTP mouse model of Parkinson's.

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.

Myeloid-specific blockade of notch signaling alleviates dopaminergic neurodegeneration in Parkinson's disease by dominantly regulating resident microglia activation through NF-κB signaling.

Yolk sac-derived microglia and peripheral monocyte-derived macrophages play a key role during Parkinson's disease (PD) progression. However, the regulatory mechanism of microglia/macrophage activation and function in PD pathogenesis remains unclear. Recombination signal-binding protein Jκ (RBP-J)-mediated Notch signaling regulates macrophage development and activation. In this study, with an 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) hydrochloride-induced acute murine PD model, we found that Notch signaling was activated in amoeboid microglia accompanied by a decrease in tyrosine hydroxylase (TH)-positive neurons. Furthermore, using myeloid-specific RBP-J knockout (RBP-JcKO) mice combined with a PD model, our results showed that myeloid-specific disruption of RBP-J alleviated dopaminergic neurodegeneration and improved locomotor activity. Fluorescence-activated cell sorting (FACS) analysis showed that the number of infiltrated inflammatory macrophages and activated major histocompatibility complex (MHC) II+ microglia decreased in RBP-JcKO mice compared with control mice. Moreover, to block monocyte recruitment by using chemokine (C-C motif) receptor 2 (CCR2) knockout mice, the effect of RBP-J deficiency on dopaminergic neurodegeneration was not affected, indicating that Notch signaling might regulate neuroinflammation independent of CCR2+ monocyte infiltration. Notably, when microglia were depleted with the PLX5622 formulated diet, we found that myeloid-specific RBP-J knockout resulted in more TH+ neurons and fewer activated microglia. Ex vitro experiments demonstrated that RBP-J deficiency in microglia might reduce inflammatory factor secretion, TH+ neuron apoptosis, and p65 nuclear translocation. Collectively, our study first revealed that RBP-J-mediated Notch signaling might participate in PD progression by mainly regulating microglia activation through nuclear factor kappa-B (NF-κB) signaling.

The mechanism of LZ-8-mediated immune response in the mouse model of Parkinson's disease

Parkinson's disease (PD) is associated with microscopic changes in the brain, particularly substantia nigra (SN). Ganoderma lucidum immunoregulatory protein (rLZ-8) is might confer protective effects against PD.We developed a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced murine model of PD and determined the effects of rLZ-8 on molecular and cellular components of SN and whole brain tissue.The levels of SOD, GSH-Px, p-JAK2 and p-STAT3 in the brain tissue and SN were downregulated, while IL-6, IL-1β, and TNF-α and MDA were upregulated. These effects were significantly reversed upon treatment rLZ-8.In summary, oxidative stress and inflammatory response in PD can be alleviated using rLZ-8.

Biochemical and behavioral effects of rosmarinic acid treatment in an animal model of Parkinson’s disease induced by MPTP

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide. The main therapeutic approach available nowadays relieves motor symptoms but does not prevent or stop neurodegeneration. Rosmarinic acid (RA), an ester of caffeic and 3,4-dihydroxyphenylacetic acids, is obtained from numerous plant species such as Salvia officinalis L. (sage) and Rosmarinus officinalis (rosemary). This compound has a wide spectrum of biological activities, such as antioxidant and anti-inflammatory, and could be an additional therapy for neurodegenerative disorders. Here we evaluated the potential neuroprotective effects of RA treatment in a murine model of PD induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Mice were separated into four groups: CN, Control/saline; RA, Rosmarinic acid/vehicle; MPTP, MPTP/saline; MPTP+RA, MPTP/RA. RA (20 mg/kg, or vehicle) was administered orally by intra-gastric gavage for 14 days, one hour before MPTP or saline injection. MPTP groups received the drug (30 mg/kg, intraperitoneally) once a day for five days (fourth to the eighth day of the experiment). MPTP-treated animals displayed hyperlocomotion behavior, which was significantly prevented by RA treatment. In addition, RA treatment increased dopaminergic signaling in the parkinsonian mice and improved the monoaminergic system in healthy animals. Analysis of alterations in the striatal mRNA expression of dopaminergic system components showed that MAO-A expression was increased in the MPTP+AR group. Overall, this study brings new evidence of the potential neuroprotective properties of RA not only in preventing behavioral features observed in PD, but also by improving neurotransmission in the healthy brain.

SUN11602, a novel bFGF mimetic, exerts neuroprotective effects in Parkinson's disease

Parkinson's disease (PD) is the second most frequent neurodegenerative disease, with a large prevalence in industrialized countries. The etiopathogenesis of PD is multifactorial and not yet fully known, however, in the last few decades, scientific world advised the establishment of a neuroinflammatory state among the possible risk factors. In this field, basic fibroblast growth factor/fibroblast growth factor receptor 1 (bFGF/FGFR1) could be a promising way to treat CNS‐mediated inflammation; however, the use of bFGF as a therapeutic agent is limited by its side effects.The novel synthetic compound SUN11602 exhibited neuroprotective activities like bFGF, but demonstrating greater safety, thus constituting a potential candidate for the treatment of neurodegenerative diseases including PD. In this perspective, this study aimed to evaluate the effect of SUN11602 administration in a murine model of MPTP‐induced PD. PD was induced by intraperitoneal injection of MPTP (80 mg/kg). SUN11602 (1, 2.5, and 5 mg/kg) was administered daily by oral gavage starting from 24 hours after the first administration of MPTP, mice were sacrificed 7 days after MPTP induction. The results obtained showed that SUN11602 administration significantly reduced the alteration of PD hallmarks, attenuating the neuroinflammatory state via modulation of glial activation, NF‐kB pathway and cytokine overexpression. Furthermore, we demonstrated that SUN11602 treatment rebalanced Ca2+ overload in neurons by regulating Ca2+‐binding proteins, inhibiting the apoptotic cascade. Therefore, considering these findings, SUN11602 could be considered a valuable pharmacological strategy for PD.

) Musa acuminata Colla Millsp ameliorates paraquat-induced memory deficit and oxidative stress in murine Parkinson disease model

Background: Parkinson disease (PD) is one of the most common neurodegenerative disorders and remains an unmet medical need. A number of epidemiological as well as case-control studies have revealed an association between pesticide exposure, especially that of paraquat (PQ) and occurrence of Musa acuminata Colla (Musaceae) also known as banana is widely cultivated for its delicious fruits and is one of the most economically important crops in the world. This study was designed to investigate the protective effffect of M. acuminata fruit extract (MAC) on paraquat-induced Parkinsonism in mice. Methods: Sixty male albino mice were randomly divided into 6 groups (n=10) and treated as follows for 21 consecutive days; Group 1: vehicle control (10 ml/kg, p.o.), group 2: vehicle + paraquat 10 mg/kg, i.p., group 3: MAC (400 mg/kg, p.o), groups 4-6: MAC (100, 200 or 400 mg/kg, p.o.) + paraquat, respectively. Behavioural studies (rotarod, Y-maze, open fifield test and bar test) were carried out on weekly basis. On day 21, one hour post-treatment the midbrains were isolated for biochemical estimation of oxidative stress parameters. Results: MAC (100, 200 or 400 mg/kg) failed to reverse paraquat induced signifificant decrease in latency to fall in rotarod test. Similarly, MAC did not affffect paraquat-induced decrease in locomotor activity in open fifield test. MAC prevented paraquat-induced decrease in percent alternation behaviour in Y-maze task. Conversely, MAC aggravated paraquat-induced cataleptic behaviour in bar test. The pretreatment of mice with MAC (200 or 400 mg/kg) signifificantly reversed paraquat-induced oxidative stress parameters in the midbrain. Conclusion: Findings from this study showed that M. acuminata prevented paraquat-induced memory impairment through improvement in antioxidant defense mechanism but failed to reverse paraquat induced locomotor defificit and cataleptic behaviour.

Rotenone induces regionally distinct α-synuclein protein aggregation and activation of glia prior to loss of dopaminergic neurons in C57Bl/6 mice

Rotenone is a naturally occurring insecticide that inhibits mitochondrial complex I and leads to neurochemical and neuropathological deficits closely resembling those in Parkinson's disease (PD). Deficits include loss of dopaminergic neurons (DAn) in the substantia nigra pars compacta (SNpc), decreased dopamine levels and aggregation of misfolded alpha-synuclein (p129). In rat models of rotenone-induced parkinsonism, the progression of neuronal injury has been associated with activation of microglia and astrocytes. However, these neuroinflammatory changes have been challenging to study in mice, in part because the systemic rotenone exposure model utilized in rats is more toxic to mice. To establish a reproducible murine model of rotenone-induced PD, we therefore investigated the progression of neuroinflammation, protein aggregation and DAn loss in C57Bl/6 mice by exposing animals to 2.5 mg/kg/day rotenone for 14 days, followed by a two-week period where neuroinflammation is allowed to progress. Our results indicate that initial cellular dysfunction leads to increased formation of proteinase K-resistant p129 aggregates in the caudate-putamen and SNpc. Clearance of these aggregates was region- and cell type-specific, with the early appearance of reactive astrocytes coinciding with accumulation of p129 in the SNpc. Phagocytic microglial cells containing p129 aggregates were observed proximal to p129+ DAn in the SNpc. The majority of neuronal loss in the SNpc occurred during the two-week period after rotenone exposure, subsequent to the peak of microglia and astrocyte activation, as well as the peak of p129 aggregation. A secondary peak of p129 coincided with neurodegeneration at later timepoints. These data indicate that systemic exposure to rotenone in C57Bl/6 mice causes progressive accumulation and regional spread of p129 aggregates that precede maximal loss of DAn. Thus, activation of glial cells and aggregation of p129 appear to drive neuronal loss following neurotoxic stress imposed by exposure to rotenone.

Melatonin Attenuates Neuroinflammation by Down-Regulating NLRP3 Inflammasome via a SIRT1-Dependent Pathway in MPTP-Induced Models of Parkinson’s Disease

BackgroundInflammasome-induced neuroinflammation is a key contributor to the pathology of Parkinson’s disease (PD). NLR family pyrin domain-containing 3 (NLRP3) inflammasome activation has been implicated in PD in postmortem human PD brains, indicating it as a potential target for PD treatment. Melatonin, a multitasking molecule, has been found to have anti-inflammatory activities, mediated by silence information regulator 1 (SIRT1). However, whether and how melatonin is involved in inflammasome-induced neuroinflammation in PD pathogenesis remains unclear.MethodsWe investigated the potential anti-inflammatory effects of melatonin in vitro and in vivo, using 1-methyl-4-phenylpyridinium (MPP+)-simulated BV2 and primary microglia cell models, and a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced murine PD model, with or without melatonin treatment. Rotarod, grip strength, and open-field tests were performed to measure the effects of melatonin on MPTP-induced motor disorders. Degeneration of dopaminergic neurons was evaluated by immunofluorescence. Changes in microglia were examined by immunofluorescence and Western blotting, and the expression levels of the involved signaling molecules were assessed by Western blotting and enzyme-linked immunosorbent assay (ELISA). Intracellular reactive oxygen species (ROS) was detected using fluorescent probes via flow cytometry.ResultsWe found that melatonin significantly alleviated motor dysfunction and prevented MPTP-induced neurotoxicity in dopaminergic neurons. Additionally, melatonin reduced MPTP-induced microglial activation and suppressed NLRP3 inflammasome activity, and also inhibited IL-1β secretion. Moreover, in MPP+-primed BV2 cells, melatonin markedly restored the downregulation of SIRT1 and attenuated the activation of the NLRP3 inflammasome. This was reversed by SIRT1 inhibitor treatment.ConclusionIn conclusion, our data demonstrated that melatonin attenuates neuroinflammation by negatively regulating NLRP3 inflammasome activation via a SIRT1-dependent pathway in MPTP-induced PD models. These findings provide novel insights into the mechanism underlying the anti-inflammatory effects of melatonin in PD.

Neural precursors cells expanded in a 3D micro-engineered niche present enhanced therapeutic efficacy in vivo.

Rationale: Stem Cells (SCs) show a great potential in therapeutics for restoring and regenerating native tissues. The clinical translation of SCs therapies is currently hindered by the inability to expand SCs in vitro in large therapeutic dosages, while maintaining their safety and potency. The use of biomaterials allows for the generation of active biophysical signals for directing SCs fate through 3D micro-scaffolds, such as the one named “Nichoid”, fabricated with two-photon laser polymerization with a spatial resolution of 100 nm. The aims of this study were: i) to investigate the proliferation, differentiation and stemness properties of neural precursor cells (NPCs) following their cultivation inside the Nichoid micro-scaffold; ii) to assess the therapeutic effect and safety in vivo of NPCs cultivated in the Nichoid in a preclinical experimental model of Parkinson's Disease (PD).Methods: Nichoids were fabricated by two photon laser polymerization onto circular glass coverslips using a home-made SZ2080 photoresist. NPCs were grown inside the Nichoid for 7 days, counted and characterized with RNA-Seq, Real Time PCR analysis, immunofluorescence and Western Blot. Then, NPCs were transplanted in a murine experimental model of PD, in which parkinsonism was induced by the intraperitoneal administration of the neurotoxin MPTP in C57/bl mice. The efficacy of engrafted Nichoid-expanded NPCs was evaluated by means of specific behavioral tests and, after animal sacrifice, with immunohistochemical studies in brain slices.Results: NPCs grown inside the Nichoid show a significantly higher cell viability and proliferation than in standard culture conditions in suspension. Furthermore, we report the mechanical conditioning of NPCs in 3D micro-scaffolds, showing a significant increase in the expression of pluripotency genes. We also report that such mechanical reprogramming of NPCs produces an enhanced therapeutic effect in the in vivo model of PD. Recovery of PD symptoms was significantly increased when animals were treated with Nichoid-grown NPCs, and this is accompanied by the recovery of dopaminergic markers expression in the striatum of PD affected mice.Conclusion: SCs demonstrated an increase in pluripotency potential when expanded inside the Nichoid, without the need of any genetic modification of cells, showing great promise for large-scale production of safe and functional cell therapies to be used in multiple clinical applications.

Exploring the Therapeutic Potentials of Highly Selective Oxygenated Chalcone Based MAO-B Inhibitors in a Haloperidol-Induced Murine Model of Parkinson's Disease.

Parkinson's disease (PD) is a neurodegenerative disorder of dopaminergic, noradrenergic, and serotonergic systems, in which dopamine, noradrenaline, and serotonin levels are depleted and lead to the development of motor and non-motor symptoms such as tremor, bradykinesia, weight changes, fatigue, depression, and visual hallucinations. Therapeutic strategies place much focus on dopamine replacement and the inhibition of dopamine metabolism. The present study was based on the known abilities of chalcones to act as molecular scaffolds that selectively inhibit MAO-B with the added advantage of binding reversibly. Recently, we synthesized a series of 26 chalcone compounds, amongst which (2E)-1-(2H-1,3-benzodioxol-5-yl)-3-(4-fluorophenyl)prop-2-en-1-one (O10) and (2E)-1-(2,3-dihydro-1,4-benzodioxin-6-yl)-3-(4-fluorophenyl)prop-2-en-1-one (O23) most inhibited MAO-B. Hence, the present study was performed to explore the molecular mechanisms responsible for the neuroprotective effect of O10 and O23 at varying doses such as 10, 20, and 30mg/kg each in a haloperidol-induced murine model of PD. Both compounds were effective (though O23 was the more effective) at ameliorating extrapyramidal and non-motor symptoms in the model and improved locomotory and exploratory behaviors, reduced oxidative stress markers, and enhanced antioxidant marker and neurotransmitter levels. Furthermore, histopathological studies showed O10 and O23 both reduced neurofibrillary tangles and plaques to almost normal control levels.

Neuroprotective effects associated with immune modulation by selected lactic acid bacteria in a Parkinson's disease model.

Parkinson's disease (PD) is a neurodegenerative process that affects the motor function and involves an inflammatory response and B vitamin deficiencies. The aim of this study was to evaluate the effect of B-group vitamin-producing and immunomodulatory lactic acid bacteria (LAB) in a murine model of PD. The effect of Lactobacillus plantarum CRL 2130 (a riboflavin producer), Streptococcus thermophilus CRL 807 (an immunomodulatory strain), and Streptococcus thermophilus CRL 808 (a folate producer) were evaluated individually and as a mixture in mice injected with 1-methyl-4-fenil-1,2,3,6-tetrahidropiridina. Motor capacity, tyrosine hydrolase in the brain, and cytokine concentrations in serum and brain tissues were evaluated in 1-methyl-4-fenil-1,2,3,6-tetrahidropiridina-treated mice after bacterial supplementation. The mice receiving the selected LAB showed significantly improved motor skills compared with those that did not receive bacterial supplementation. When given the mixture of all 3 strains together, the animals had higher brain tyrosine hydrolase-positive cell counts, decreased inflammatory cytokines interleukin 6 and tumor necrosis factor alpha in serum, and increased antiinflammatory cytokine interleukin 10 in serum and brain tissues compared with animals that did not receive LAB supplementation. The results showed the potential of a selected LAB mixture to improve motor behavior and neuroinflammation in PD. This probiotic mixture could be used as an adjunct treatment in the control of PD.

NIR-II-Activated Yolk-Shell Nanostructures as an Intelligent Platform for Parkinsonian Therapy.

Despite the relative severity of Parkinson's disease (PD), to date, there has been only limited success in preventing or treating this condition owing to the low permeability of the blood-brain barrier (BBB), which makes the cerebral delivery of pharmaceutical agents very challenging. In the present study, we explored an approach to increasing BBB permeability via the use of mesoporous silica-encapsulated gold nanorods (MSNs-AuNRs) that could reliably achieve a robust photothermal effect in response to second near-infrared (NIR-II) irradiation. To test the potential anti-Parkinsonian activity, we loaded MSNs-AuNRs with the frequently utilized anti-PD agent quercetin (QCT) to yield MSNs-AuNRs@QCT. Following NIR-II irradiation, we observed a dramatical increase in QCT transfer through the BBB, indicating that MSNs-AuNRs may enhance BBB permeability via the photothermal effect. These findings were further supported by rat pharmacokinetic studies, which clearly revealed that the combination of MSNs-AuNRs and NIR-II irradiation was associated with significantly improved brain accumulation. In a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced murine model of PD, we also found that intravenous MSNs-AuNRs@QCT delivery and subsequent NIR-II irradiation was sufficient to markedly reduce the neurological abnormalities in these mice. Together, this combination offers promising potential as a nanoplatform for neuroprotective drug delivery and treatment of PD.

Identification of unique and shared mitochondrial DNA mutations in neurodegeneration and cancer by single-cell mitochondrial DNA structural variation sequencing (MitoSV-seq).

BackgroundPoint mutations and structural variations (SVs) in mitochondrial DNA (mtDNA) contribute to many neurodegenerative diseases. Technical limitations and heteroplasmy, however, have impeded their identification, preventing these changes from being examined in neurons in healthy and disease states.MethodsWe have developed a high-resolution technique—Mitochondrial DNA Structural Variation Sequencing (MitoSV-seq)—that identifies all types of mtDNA SVs and single-nucleotide variations (SNVs) in single neurons and novel variations that have been undetectable with conventional techniques.FindingsUsing MitoSV-seq, we discovered SVs/SNVs in dopaminergic neurons in the Ifnar1−/− murine model of Parkinson disease. Further, MitoSV-seq was found to have broad applicability, delivering high-quality, full-length mtDNA sequences in a species-independent manner from human PBMCs, haematological cancers, and tumour cell lines, regardless of heteroplasmy. We characterised several common SVs in haematological cancers (AML and MDS) that were linked to the same mtDNA region, MT-ND5, using only 10 cells, indicating the power of MitoSV-seq in determining single-cancer-cell ontologies. Notably, the MT-ND5 hotspot, shared between all examined cancers and Ifnar1−/− dopaminergic neurons, suggests that its mutations have clinical value as disease biomarkers.InterpretationMitoSV-seq identifies disease-relevant mtDNA mutations in single cells with high resolution, rendering it a potential drug screening platform in neurodegenerative diseases and cancers.FundingThe Lundbeck Foundation, Danish Council for Independent Research-Medicine, and European Union Horizon 2020 Research and Innovation Programme.

MPTP-Induced Impairment of Cardiovascular Function.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the accumulation of Lewy bodies and loss of dopaminergic neurons in the substantia nigra pars compacta (SNpC). MPTP is widely used to generate murine PD model. In addition to classical motor disorders, PD patients usually have non-motor symptoms related to autonomic impairment, which precedes decades before the motor dysfunction. This study's objective is to examine the effects of MPTP on noradrenergic neurons in the hindbrain, thereby on the cardiovascular function in mice. Adult mice received 10mg/kg/day of MPTP (4 consecutive days) to generate PD model. Systolic blood pressure was measured by tail cuff system in conscious mice, and baroreflex sensitivity was evaluated by heart rate alteration in response to a transient increase or decrease in blood pressure induced by intravenous infusion of phenylalanine (PE) or sodium nitroprusside (SNP) in anesthetized condition, respectively. Baseline heart rate and heart rate variability were analyzed in both sham and MPTP-treated mice. Dopamine, norepinephrine, and related metabolites in the plasma and brain tissues including SNpC, locus coeruleus (LC), rostroventrolateral medulla (RVLM), and nucleus tractus solitarii (NTS) were measured by liquid chromatography-mass spectrometry (LC-MS). Tyrosine hydroxylase-positive (TH+) neurons in above nuclei were quantified by immunoreactivities. We found that in addition to the loss of TH+ neurons in SNpC, MPTP treatment induced a dramatic reduction of TH+ cell counts in the LC, RVLM, and NTS. These are associated with significant decreases of dopamine, norepinephrine, and epinephrine in above nuclei. Meanwhile, MPTP induced a lasting effect of baroreflex desensitization, tachycardia, and decreased heart rate variability compared to the sham mice. Notably, MPTP treatment elevated sympathetic outflow and suppressed parasympathetic tonicity according to the heart rate power spectrum analysis. Our results indicate that the loss of TH+ neurons in the brainstem by MPTP treatment led to impaired autonomic cardiovascular function. These results suggest that MPTP treatment can be used to study the autonomic dysfunction in murine model.

Modafinil alleviates levodopa-induced excessive nighttime sleepiness and restores monoaminergic systems in a nocturnal animal model of Parkinson's disease

Treatment with dopaminergic agents result excessive daytime sleepiness (EDS) and some studies have shown the benefit of using modafinil for treating excessive daytime sleepiness of Parkinson's disease (PD) patient. We investigated whether modafinil have ameliorative properties against levodopa induced excessive nighttime sleepiness (ENS) in MPTP-treated murine nocturnal PD model. Our EEG analyses of whole day recordings revealed that modafinil reduce ENS of this nocturnal PD models with levodopa medications. Therefore, we investigated whether, modafinil post-treatment followed by MPTP shows any effect on monoamine contents of brain and found to robustly increased noradrenaline (NA) concentration of MPTP treated mice. Modafinil post-treatment, in neurorestorative context (5 days post-lesion) led to increased striatal dopamine (DA) concentrations of MPTP-treated mice. Here, we first confirmed that modafinil ameliorates levodopa induced excessive sleepiness and restores monoaminergic systems. The arousal and anti-parkinsonian effects displayed by modafinil indicate that in combination with dopaminergic agents, modafinil co-administration may be worthwhile in trying to suppress the excessive daytime sleepiness and progressive dopaminergic neuron loss in PD.

Immunization with α-synuclein/Grp94 reshapes peripheral immunity and suppresses microgliosis in a chronic Parkinsonism model.

Neuroinflammation mediated by chronically activated microglia, largely caused by abnormal accumulation of misfolded α-synuclein (αSyn) protein, is known to contribute to the pathophysiology of Parkinson's disease (PD). In this work, based on the immunomodulatory activities displayed by particular heat-shock proteins (HSPs), we tested a novel vaccination strategy that used a combination of αSyn and Grp94 (HSPC4 or Gp96) chaperone and a murine PD model. We used two different procedures, first, the adoptive transfer of splenocytes from αSyn/Grp94-immunized mice to recipient animals, and second, direct immunization with αSyn/Grp94, to study the effects in a chronic mouse MPTP-model of parkinsonism. We found that both approaches promoted a distinct profile in the peripheral system-supported by humoral and cellular immunity-consisting of a Th1-shifted αSyn-specific response accompanied by an immune-regulatory/Th2-skewed general phenotype. Remarkably, this mixed profile sustained by αSyn/Grp94 immunization led to strong suppression of microglial activation in the substantia nigra and striatum, pointing to a newly described positive effect of anti-αSyn Th1-responses in the context of PD. This strategy is the first to target αSyn and report the suppression of PD-associated microgliosis. Overall, we show that the αSyn/Grp94 combination supports a distinct and long-lasting immune profile in the peripheral system, which has an impact at the CNS level by suppressing chronic microglial activation in an MPTP model of PD. Furthermore, our study demonstrates that reshaping peripheral immunity by vaccination with appropriate misfolding protein/HSP combinations could be highly beneficial as a treatment for neurodegenerative misfolding diseases.

Cholinergic and Dopaminergic Alterations in Nigrostriatal Neurons Are Involved in Environmental Enrichment Motor Protection in a Mouse Model of Parkinson's Disease.

Parkinson's disease (PD) is the second most common neurodegenerative disease in the world, being characterized by dopaminergic neurodegeneration of substantia nigra pars compacta. PD pharmacotherapy has been based on dopamine replacement in the striatum with the dopaminergic precursor 3,4-dihydroxyphenylalanine (L-DOPA) and/or with dopaminergic agonists, alongside anticholinergic drugs in order to mitigate the motor abnormalities. However, these practices neither prevent nor stop the progression of the disease. Environmental enrichment (EE) has effectively prevented several neurodegenerative processes, mainly in preclinical trials. Several studies have demonstrated that EE induces biological changes, bearing on cognitive enhancement, neuroprotection, and on the attenuation of the effects of stress, anxiety, and depression. Herein, we investigated whether EE could prevent the motor, biochemical, and molecular abnormalities in a murine model of PD induced by 1-methyl-4-phenyl-2,3-dihydropyridine (MPTP). Our results show that EE does not prevent the dopaminergic striatal depletion induced by MPTP, despite having averted the MPTP-induced hyperlocomotion. However, it was able to slow down and avoid, respectively, the 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) depletion. Analysis of dopaminergic mRNA alterations in the midbrain showed that D1R expression was increased by MPTP, while the normal expression level of this receptor was restored by EE. As for the cholinergic system, MPTP led to a decrease in the ChAT gene expression while increasing the expression of both AChE and M1R. EE attenuated and prevented-respectively-ChAT and M1R gene expression alterations triggered by MPTP in the midbrain. Overall, our data brings new evidence supporting the neuroprotective potential of EE in PD, focusing on the interaction between dopaminergic and cholinergic systems.

Neuroprotective effect of bee venom is mediated by reduced astrocyte activation in a subchronic MPTP-induced model of Parkinson's disease.

Bee venom (BV), also known as apitoxin, is widely used in traditional oriental medicine to treat immune-related diseases. Recent studies suggest that BV could be beneficial for the treatment of neurodegenerative diseases. Parkinson's disease (PD) is the second most common neurodegenerative disease next to Alzheimer's disease, and PD pathologies are closely associated with neuroinflammation. Previous studies have suggested the neuroprotective effects of BV in animal models of PD are due to the modulation of inflammation. However, the molecular mechanisms responsible for the anti-neuroinflammatory effect of BV have not been elucidated in astrocytes. Here, the authors investigated the neuroprotective effects of BV and pramipexole (PPX; a positive control) in a subchronic MPTP-induced murine PD model. Both BV and PPX prevented MPTP-induced impairments in motor performance and reduced dopaminergic neuron loss, and furthermore, these neuroprotective effects of BV and PPX were found to be associated with reduced astroglial activation in vivo PD model. However, in MPP(+) treated primary cultured astrocytes, BV modulated astrocyte activation, whereas PPX did not, indicating that the neuroprotective effects of PPX were not mediated by neuroinflammation. These findings suggest that BV should be considered a potential therapeutic or preventive agent for PD and other neuroinflammatory associated disorders.

Medicinal plant Combretum leprosum mart ameliorates motor, biochemical and molecular alterations in a Parkinson's disease model induced by MPTP

Ethnopharmacological relevanceCombretum leprosum is a popular medicinal plant distributed in north and northeastern regions of Brazil. Many different parts of this plant are used in traditional medicine to treat several inflammatory diseases. Parkinson's disease (PD) is a disorder associated with inflammatory toxic factors and the treatments available provide merely a delay of the neurodegeneration. Aim of the studyWe investigated the potential neuroprotective properties of the C. leprosum ethanolic extract (C.l.EE) in a murine model of PD using the toxin 1-methyl-4 phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP). Materials and methodsThe mice were split into four groups: V/S (vehicle/saline), E/S (extract/saline), V/M (vehicle/MPTP) and E/M (extract/ MPTP). Mice received MPTP (30mg/kg, i.p.) or vehicle (10ml/kg, i.p.) once a day for 5 consecutive days and vehicle (10ml/kg) or C.l.EE (100mg/kg) orally by intra-gastric gavage (i.g.) during a 14-d period, starting 3 days before the first MPTP injection. All groups were assessed for behavioural impairments (amphetamine-induced locomotor activity and muscle strength), dopamine content in striatum using high performance liquid chromatography (HPLC), tyrosine hydroxylase (TH) and dopamine transporter (DAT) gene expressions using qPCR. ResultsAnimals were injected with d-amphetamine (2mg/kg) and the activity was recorded. Amphetamine-induced hyperlocomotion was observed in all groups; however animals treated with MPTP showed exacerbated hyperlocomotion (approximately 3 fold increase compared to control groups). By contrast, mice treated with MPTP that received C.l.EE exhibited attenuation of the hyperlocomotion and did not differ from control groups. Muscle strength test pointed that C.l.EE strongly avoided muscular deficits caused by MPTP (approximately 2 fold increase compared to V/M group). Dopamine and its metabolites were measured in the striatum. The V/M group presented a dopamine reduction of 80%. On the other hand, the E/M group exhibited an increase in dopamine and its metabolites levels (approximately 3 fold increase compared to V/M group). Tyrosine hydroxylase (TH) and dopamine transporter (DAT) gene expressions were significantly reduced in the V/M group (60%). Conversely, C.l.EE treatment was able to increase the mRNA levels of those genes in the E/M group (approximately 2 fold for TH and DAT). ConclusionsThese data show, for the first time, that C. leprosum ethanolic extract prevented motor and molecular changes induced by MPTP, and partially reverted dopamine deficit. Thus, our results demonstrate that C.l.EE has potential for the treatment and prevention of PD.