The study aimed to investigate the effect of the CD200R1 gene deletion on microglia activation and nigrostriatal dopamine neuron loss in the Parkinson's disease (PD) process. The CRISPR-Cas9 technology was applied to construct the CD200R1^-/- mice. The primary microglia cells of wild-type and CD200R1^-/- mice were cultured and treated with bacterial lipopolysaccharide (LPS). Microglia phagocytosis level was assessed by a fluorescent microsphere phagocytosis assay. PD mouse model was prepared by nigral stereotaxic injection of recombinant adeno-associated virus vector carrying human α-synuclein (α-syn). The changes in the motor behavior of the mice with both genotypes were evaluated by cylinder test, open field test, and rotarod test. Immunohistochemical staining was used to assess the loss of dopamine neurons in substantia nigra. Immunofluorescence staining was used to detect the expression level of CD68 (a key molecule involved in phagocytosis) in microglia. The results showed that CD200R1 deletion markedly enhanced LPS-induced phagocytosis in vitro by the microglial cells. In the mouse model of PD, CD200R1 deletion exacerbated motor behavior impairment and dopamine neuron loss in substantia nigra. Fluorescence intensity analysis results revealed a significant increase in CD68 expression in microglia located in the substantia nigra of CD200R1^-/- mice. The above results suggest that CD200R1 deletion may further activates microglia by promoting microglial phagocytosis, leading to increased loss of the nigrostriatal dopamine neurons in the PD model mice. Therefore, targeting CD200R1 could potentially serve as a novel therapeutic target for the treatment of early-stage PD.
Animals ; Microglia/physiology* ; Mice ; Phagocytosis ; Parkinson Disease/genetics* ; Disease Models, Animal ; Receptors, Cell Surface/physiology* ; Dopaminergic Neurons/pathology* ; Antigens, CD/metabolism* ; Gene Deletion ; Substantia Nigra ; Mice, Inbred C57BL ; Mice, Knockout ; Cells, Cultured ; Male ; alpha-Synuclein ; CD68 Molecule ; Orexin Receptors

Parkinson's disease (PD) is a multifactorial disorder of the nervous system where a progressive loss of dopaminergic neurons exist. However, the pathogenesis of PD remains undefined, which becomes the main limitation for the development of clinical PD treatment. Demethylenetetrahydroberberine (DMTHB) is a novel derivative of natural product berberine. This study was aimed to explore the neuroprotective effects and pharmacological mechanism of DMTHB on Parkinson's disease using C57BL/6 mice. A PD model of mice was induced by administration of MPTP (20 mg·kg^-1) and probenecid (200 mg·kg^-1) twice per week for five weeks. The mice were administered with DMTHB daily by gavage at the dose of 5 and 50 mg·kg^-1 for one- week prophylactic treatment and five-week theraputic treatment. The therapeutic effects of DMTHB were evaluated by behavior tests (the open field, rotarod and pole tests), immunohistochemical staining of tyrosine hydroxylase (TH), Nissl staining and biochemical assays. The molecular mechanisms of DMTHB on the key biomarkers of PD pathological states were analyzed by Western blot (WB) and qRT-PCR. DMTHB treatment alleviated the behavioral disorder induced by MPTP-probenecid. Nissl staining and TH staining showed that the damage of dopaminergic neurons in the substantia nigra was remarkably suppressed by DMTHB treatment. Western blot results showed that the ratio of Bcl-2/Bax and TH increased, but the level of α-synuclein (α-syn) was remarkably reduced, which indicated that the apoptosis of dopaminergic neurons in mice was significantly reduced. The protein phosphorylation of p-PI3K, p-AKT and p-mTOR also increased about 2-fold, compared with the model group. Furthermore, qRT-PCR results demonstrated that the mRNA levels of pro-inflammatory cytokines, IL-1β and TNF-α, were reduced, but the level of anti-inflammatory cytokine IL-10 increased after DMTHB treatment. Finally, the cellular assay displayed that DMTHB was also a strong antioxidant to protect neuron cell line PC12 by scavenging ROS. In this study, we demonstrated DMTHB alleviates the behavioral disorder and protects dopaminergic neurons through multiple-target effects includubg anti-apoptotic, anti-inflammatory and antioxidant effects.
Animals ; Dopaminergic Neurons/pathology* ; Mice ; Mice, Inbred C57BL ; Parkinson Disease/pathology* ; Parkinsonian Disorders/chemically induced* ; Substantia Nigra

Objective: To observe the dynamic changes of brainstem locus coeruleus (LC) damage in Parkinson' s disease (PD) -like mice by paraquat (PQ) . Methods: In October 2019, 36 male C57BL/6 mice were randomly divided into the exposure group and the control group, with 18 mice in each group. The mice in the exposure group were given intraperitoneal injection of 15 mg/kg PQ, and the mice in the control group were given intraperitoneal injection of 0.9% saline, twice a week for 8 weeks. Neurobehavioral changes (pole climbing test, swimming test, open field test, tail hanging test, high plus maze test and water maze test) were observed at 4 weeks, 6 weeks and 8 weeks, respectively, and the changes of motor ability, emotion and cognitive function were evaluated. The brain tissue of mice were taken and stained with Hematoxylin-Eosin (HE) to observe the pathological changes of LC. Nissl staining was used to detect the changes of neuronal Nissl bodies in LC. Immunohistochemistry (IHC) staining was used to detect the expression of neuron nuclear antigen (NeuN) , dopamine (DA) neurons and norepinephrine (NE) neuron markers tyrosine hydroxylase (TH) , α-synuclein (α-syn) in substantia nigra (SN) and LC. The expression levels of NeuN, TH and α-syn in the midbrain and brainstem were detected by Western blotting. TUNEL staining was used to detect neuronal apoptosis in LC. Results: Compared with the 4th week of PQ exposure group, the time of pole climbing and swimming immobility were gradually increased, the ratio of open arm residence time of high plus maze test and the number of times of the platform and the residence time of platform quadrant in water maze test were gradually decreased (P<0.05) in the exposure group with the progress of exposure time. The results of HE and Nissl staining showed that the neurons in LC gradually arranged loosely, the nucleus were deeply stained, the cytoplasm was pyknosis, and the number of Nissl bodies gradually decreased (P<0.05) in the exposure group with the progress of exposure time. IHC results showed that the number of NeuN and TH positive cells in SN and LC of mice were gradually decreased, and the positive expression of α-syn was gradually increased (P<0.05) in the exposure group with the progress of exposure time. Western blotting results showed that the expression levels of NeuN and TH in the midbrain and brainstem were gradually decreased, and the expression level of α-syn was gradually increased (P<0.05) in the exposure group with the progress of exposure time. TUNEL staining showed that the apoptosis rates of neurons in LC were gradually increased (P<0.05) in the exposure group with the progress of exposure time. Conclusion: PQ induces progressive damage in the LC area of PD-like mice, which may be caused by the abnormal accumulation of pathological α-syn in the LC area.
Animals ; Dopaminergic Neurons ; Locus Coeruleus/pathology* ; Male ; Mice ; Mice, Inbred C57BL ; Paraquat/toxicity* ; Parkinson Disease/metabolism* ; Substantia Nigra ; Tyrosine 3-Monooxygenase/metabolism*

Parkinson's disease (PD) is the second most common neurodegenerative disease, characterized by loss of dopaminergic (DA) neurons in the dense part of the substantia nigra (SNpc). Postmortem analysis of PD patients and experimental animal studies found that microglial cell activation and increased levels of pro-inflammatory factors were common features of PD brain tissue. At the same time, the invasion and accumulation of peripheric immune cells were detected in the brain of PD patients. In this paper, peripheral inflammation across the blood-brain barrier (BBB), the misfolded α-synuclein (α-syn)-induced microglial cell activation and intracerebral inflammation in PD are summarized, providing potential therapeutic measures for delaying the onset of PD.
Animals ; Blood-Brain Barrier ; Dopaminergic Neurons ; pathology ; Humans ; Inflammation ; pathology ; Microglia ; Parkinson Disease ; pathology ; Substantia Nigra ; pathology ; alpha-Synuclein

The traditionally used oriental herbal medicine Moutan Cortex Radicis [MCR; Paeonia Suffruticosa Andrews (Paeoniaceae)] exerts anti-inflammatory, anti-spasmodic, and analgesic effects. In the present study, we investigated the therapeutic effects of differently fractioned MCR extracts in a 6-hydroxydopamine (OHDA)-induced Parkinson's disease model and neuro-blastoma B65 cells. Ethanol-extracted MCR was fractionated by n-hexane, butanol, and distilled water. Adult Sprague-Dawley rats were treated first with 20 μg of 6-OHDA, followed by three MCR extract fractions (100 or 200 mg·kg) for 14 consecutive days. In the behavioral rotation experiment, the MCR extract-treated groups showed significantly decreased number of net turns compared with the 6-OHDA control group. The three fractions also significantly inhibited the reduction in tyrosine hydroxylase-positive cells in the substantia nigra pars compacta following 6-OHDA neurotoxicity. Western blotting analysis revealed significantly reduced tyrosine hydroxylase expression in the substantia nigra pars compacta in the 6-OHDA-treated group, which was significantly inhibited by the n-hexane or distilled water fractions of MCR. B65 cells were exposed to the extract fractions for 24 h prior to addition of 6-OHDA for 30 min; treatment with n-hexane or distilled water fractions of MCR reduced apoptotic cell death induced by 6-OHDA neurotoxicity and inhibited nitric oxide production and neuronal nitric oxide synthase expression. These results showed that n-hexane- and distilled water-fractioned MCR extracts inhibited 6-OHDA-induced neurotoxicity by suppressing nitric oxide production and neuronal nitric oxide synthase activity, suggesting that MCR extracts could serve as a novel candidate treatment for the patients with Parkinson's disease.
Animals ; Anti-Inflammatory Agents ; pharmacology ; therapeutic use ; Antiparkinson Agents ; pharmacology ; therapeutic use ; Cell Death ; drug effects ; Cell Line ; Disease Models, Animal ; Drugs, Chinese Herbal ; chemistry ; Neurons ; pathology ; Nitric Oxide ; analysis ; Nitric Oxide Synthase Type I ; biosynthesis ; Oxidopamine ; toxicity ; Paeonia ; chemistry ; Parkinsonian Disorders ; chemically induced ; drug therapy ; Phytotherapy ; Plant Extracts ; pharmacology ; therapeutic use ; Plants, Medicinal ; Rats ; Rats, Sprague-Dawley ; Substantia Nigra ; drug effects ; enzymology ; Tyrosine 3-Monooxygenase ; genetics ; metabolism

The characteristic features of Alzheimer's disease (AD) are the appearance of extracellular amyloid-beta (Aβ) plaques and neurofibrillary tangles in the intracellular environment, neuronal death and the loss of synapses, all of which contribute to cognitive decline in a progressive manner. A number of hypotheses have been advanced to explain AD. Abnormal tau phosphorylation may contribute to the formation of abnormal neurofibrillary structures. Many different structures are susceptible to AD, including the reticular formation, the nuclei in the brain stem (e.g., raphe nucleus), thalamus, hypothalamus, locus ceruleus, amygdala, substantia nigra, striatum, and claustrum. Excitotoxicity results from continuous, low-level activation of N-methyl-D-aspartate (NMDA) receptors. Premature synaptotoxicity, changes in neurotransmitter expression, neurophils loss, accumulation of amyloid β-protein deposits (amyloid/senile plaques), and neuronal loss and brain atrophy are all associated with stages of AD progression. Several recent studies have examined the relationship between Aβ and NMDA receptors. Aβ-induced spine loss is associated with a decrease in glutamate receptors and is dependent upon the calcium-dependent phosphatase calcineurin, which has also been linked to long-term depression.
Alzheimer Disease* ; Amygdala ; Amyloid ; Animals, Genetically Modified ; Atrophy ; Basal Ganglia ; Brain Stem ; Brain* ; Calcineurin ; Depression ; Hypothalamus ; Locus Coeruleus ; N-Methylaspartate* ; Neurofibrillary Tangles ; Neurons ; Neurotransmitter Agents ; Pathology* ; Phosphorylation ; Receptors, Glutamate ; Receptors, N-Methyl-D-Aspartate* ; Reticular Formation ; Risk Factors* ; Spine ; Substantia Nigra ; Synapses ; tau Proteins* ; Thalamus

Parkinson's disease (PD) is an age-related progressive neurodegenerative disease associated with selective loss of dopaminergic neurons. The characteristic hallmark of the disease is intracytoplasmic proteinacious inclusion bodies called Lewy bodies, primarily consisting of a presynaptic protein alpha-synuclein. Oxidative stress-mediated damage to macromolecules have been shown to occur frequently in PD. Oxidative damage to DNA in the form of oxidized guanine (8-oxodG) accumulates in both the mitochondrial and nuclear DNA of dopaminergic neurons of the substantia nigra in PD. 8-oxodG-mediated transcriptional mutagenesis has been shown to have the potential to alter phenotype of cells through production of mutant pool of proteins. This review comprehensively summarizes the role of oxidative stress-mediated damage incurred during neurodegeneration, and highlights the scope of transcriptional mutagenesis event in leading to alpha-synuclein aggregation as seen in PD.
Amino Acid Sequence ; Animals ; Deoxyguanosine/*analogs & derivatives/metabolism ; Humans ; Molecular Sequence Data ; Mutagenesis ; *Oxidative Stress ; Parkinson Disease/*genetics/metabolism/pathology ; Protein Aggregation, Pathological/*genetics/metabolism/pathology ; Substantia Nigra/metabolism/*pathology ; Transcription, Genetic ; alpha-Synuclein/chemistry/*genetics

Parkinson's disease (PD) is characterized by the selective loss of dopaminergic neurons of the substantia nigra pars compacta (SNc) with motor and nonmotor symptoms. Defective mitochondrial function and increased oxidative stress (OS) have been demonstrated as having an important role in PD pathogenesis, although the underlying mechanism is not clear. The etiopathogenesis of sporadic PD is complex with variable contributions of environmental factors and genetic susceptibility. Both these factors influence various mitochondrial aspects, including their life cycle, bioenergetic capacity, quality control, dynamic changes of morphology and connectivity (fusion, fission), subcellular distribution (transport), and the regulation of cell death pathways. Mitochondrial dysfunction has mainly been reported in various non-dopaminergic cells and tissue samples from human patients as well as transgenic mouse and fruit fly models of PD. Thus, the mitochondria represent a highly promising target for the development of PD biomarkers. However, the limited amount of dopaminergic neurons prevented investigation of their detailed study. For the first time, we established human telomerase reverse transcriptase (hTERT)-immortalized wild type, idiopathic and Parkin deficient mesenchymal stromal cells (MSCs) isolated from the adipose tissues of PD patients, which could be used as a good cellular model to evaluate mitochondrial dysfunction for the better understanding of PD pathology and for the development of early diagnostic markers and effective therapy targets of PD. In this review, we examine evidence for the roles of mitochondrial dysfunction and increased OS in the neuronal loss that leads to PD and discuss how this knowledge further improve the treatment for patients with PD.
Animals ; Cell Death ; Diptera ; Dopaminergic Neurons ; Energy Metabolism ; Fruit ; Genetic Predisposition to Disease ; Humans ; Life Cycle Stages ; Mesenchymal Stromal Cells ; Mice ; Mice, Transgenic ; Mitochondria ; Neurons ; Oxidative Stress ; Parkinson Disease* ; Pathology ; Quality Control ; Substantia Nigra ; Telomerase ; Biomarkers

OBJECTIVETo discuss the protective effect of alkaloids from Piper longum (PLA) in rat dopaminergic neuron injury of 6-OHDA-induced Parkinson's disease and its possible mechanism.

METHODThe rat PD model was established by injecting 6-OHDA into the unilateral striatum with a brain solid positioner. The PD rats were divided into the PLA group (50 mg x kg(-1) x d(-1)), the madorpa group (50 mg x kg(-1) x d(-1)) and the model group, with 15 rats in each group. All of the rats were orally given drugs once a day for 6 weeks. Meanwhile, other 15 rats were randomly selected as the sham operation group, and only injected with normal saline in the unilateral striatum. The behavioral changes were observed with the apomorphine (APO)-induced rotation and rotary rod tests. The number of tyrosine hydroxylase (TH)-positive cells in rat substantia nigra and the density of TH-positive fibers in striatum were detected by tyrosine hydroxylase immunohistochemistry. The content of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), glutathione (GSH), catalase (CAT), malondialdehyde (MDA), nitric oxide (NO) and nitric oxide synthase (NOS) in rat substantia nigra and striatum were measured by the spectrophotometric method.

RESULTAfter being induced by APO, PD rats showed obvious rotation behaviors, with decreased time stay on rotary rod and significant reduction in the number of TH-positive cells in sustantia nigra and the density of TH-positive fibers in striatum. The activities of SOD, GSH-Px, CAT, the content of GSH and the total antioxidant capacity significantly decreased, whereas the activities of NOS and the content of MDA, NO significantly increased. PLA could significantly improve the behavioral abnormality of PD rats and increase the number of TH-positive cells in sustantia nigra and the density of TH-positive fibers in striatum. It could up-regulate the activities of SOD, GSH-Px, CAT, the content of GSH and the total antioxidant capacity, and decrease the content of NOS and the content of MDA, NO.

CONCLUSIONAlkaloids from P. longum shows the protective effect in substantia nigra cells of 6-OHDA-induced PD model rats. Its mechanism may be related with their antioxidant activity.

Administration, Oral ; Alkaloids ; administration & dosage ; pharmacology ; Animals ; Apomorphine ; pharmacology ; Catalase ; metabolism ; Dopamine Agonists ; pharmacology ; Dopaminergic Neurons ; drug effects ; metabolism ; pathology ; Glutathione ; metabolism ; Glutathione Peroxidase ; metabolism ; Male ; Malondialdehyde ; metabolism ; Motor Activity ; drug effects ; Neostriatum ; drug effects ; metabolism ; Nitric Oxide ; metabolism ; Nitric Oxide Synthase ; metabolism ; Oxidopamine ; Parkinson Disease, Secondary ; chemically induced ; physiopathology ; prevention & control ; Piper ; chemistry ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Substantia Nigra ; drug effects ; metabolism ; Superoxide Dismutase ; metabolism ; Tyrosine 3-Monooxygenase ; metabolism

Destruction of dopaminergic neurons in the substantia nigra pars compacta (SNpc) is a common pathophysiology of Parkinson's disease (PD). Characteristics of PD patients include bradykinesia, muscle rigidity, tremor at rest and disturbances in balance. For about four decades, PD animal models have been produced by toxin-induced or gene-modified techniques. However, in mice, none of the gene-modified models showed all 4 major criteria of PD. Moreover, distinguishing between PD model pigs and normal pigs has not been well established. Therefore, we planned to produce a pig model for PD by chronic subcutaneous administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), neurotoxin. Changes in behavioral patterns of pigs were thoroughly evaluated and a new motor scoring system was established for this porcine model that was based on the Unified Parkinson's Disease Rating Scale (UPDRS) in human PD patients. In summary, this motor scoring system could be helpful to analyze the porcine PD model and to confirm the pathology prior to further examinations, such as positron emission tomography-computed tomography (PET-CT), which is expensive, and invasive immunohistochemistry (IHC) of the brain.
1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine* ; Animals ; Brain ; Dopaminergic Neurons ; Electrons ; Humans ; Hypokinesia ; Immunohistochemistry ; Injections, Subcutaneous* ; Mice ; Models, Animal ; Muscle Rigidity ; Parkinson Disease* ; Pathology ; Substantia Nigra ; Swine ; Tremor