INTRODUCTION: Parkinson's disease (PD) is a second most common neurodegenerative disorder which affects 1 % to 2% of people older than 60 years and is characterized by cardinal features of bradykinesia, rigidity, and rest tremor (2). Most of the motor disability experienced by patients results from progressive loss of dopaminergic neurons of the Substantia Nigra pars compacta (SNpc). However, recent studies have shown that PD is also associated with extensive non-dopaminergic pathology. Recent trend in the treatment of PD include development of new drugs that will not only address the symptom relief but will also ameliorate the progression of dopaminergic neuron degeneration (3).
OBJECTIVE: To assess the evidence from randomized controlled trials the effects of Rasagiline compared with placebo in the treatment of patients with Parkinson's disease
DESIGN: Meta-analysis of 3 randomized trials identified through Medline/Pubmed and Cochrane Library. Summary of the outcome variables was computed using difference of two means of the United Parkinson's disease rating scale (UPDRS) score and their corresponding standard error of the means under fixed effects models. The chi-square test was done to test heterogeneity. Statistical analysis was done using Revman version 5.
RESULTS: The sample size of the studies ranged from 13 to 595 patients. The mean age of the trial participants were in the 60s with a relatively narrow standard deviation. All studies were randomized and placebo controlled. The main outcome measure was change in the UPDRS score from baseline. The mean difference between Rasagiline 1 mg and placebo is -3.06 (95% CI -3.81, -2.31) and Rasagiline 2mg and placebo is -3.17 (95% CI -3.92, -2.42). The overall effect was statistically significant (z=8.01; p<0.00001 and z=8.28; p<0.00001) in favor of Rasagiline 1mg and 2mg using the fixed effects model.
CONCLUSION: Based on this meta-analysis, Rasagiline is effective as monotherapy in early Parkinson's disease.

The accumulation of pathological α-synuclein (α-syn) in the central nervous system and the progressive loss of dopaminergic neurons in the substantia nigra pars compacta are the neuropathological features of Parkinson's disease (PD). Recently, the findings of prion-like transmission of α-syn pathology have expanded our understanding of the region-specific distribution of α-syn in PD patients. Accumulating evidence suggests that α-syn aggregates are released from neurons and endocytosed by glial cells, which contributes to the clearance of α-syn. However, the activation of glial cells by α-syn species produces pro-inflammatory factors that decrease the uptake of α-syn aggregates by glial cells and promote the transmission of α-syn between neurons, which promotes the spread of α-syn pathology. In this article, we provide an overview of current knowledge on the role of glia and α-syn pathology in PD pathogenesis, highlighting the relationships between glial responses and the spread of α-syn pathology.
Humans ; Parkinson Disease/pathology* ; alpha-Synuclein/metabolism* ; Dopaminergic Neurons/metabolism* ; Pars Compacta/metabolism*

Corpus Striatum ; Dopaminergic Neurons ; Humans ; Mesencephalon ; Parkinson Disease/drug therapy* ; Pars Compacta ; Substantia Nigra

BACKGROUND: Quantitative susceptibility mapping (QSM) has been used to measure iron accumulation in the deep nuclei of patients with Parkinson's disease (PD). This study examined the relationship between non-motor symptoms (NMSs) and iron accumulation in the deep nuclei of patients with PD. METHODS: The QSM data were acquired from 3-Tesla magnetic resonance imaging (MRI) in 29 patients with early PD and 19 normal controls. The Korean version of the NMS scale (K-NMSS) was used for evaluation of NMSs in patients. The patients were divided into high NMS and low NMS groups. The region-of-interest analyses were performed in the following deep nuclei: red nucleus, substantia nigra pars compacta, substantia nigra pars reticulata, dentate nucleus, globus pallidus, putamen, and head of the caudate nucleus. RESULTS: Thirteen patients had high NMS scores (total K-NMSS score, mean = 32.1), and 16 had low NMS scores (10.6). The QSM values in the deep were not different among the patients with high NMS scores, low NMS scores, and controls. The QSM values were not correlated linearly with K-NMSS total score after adjusting the age at acquisition of brain MRI. CONCLUSION: The study demonstrated that the NMS burdens are not associated with iron accumulation in the deep nuclei of patients with PD. These results suggest that future neuroimaging studies on the pathology of NMSs in PD should use more specific and detailed clinical tools and recruit PD patients with severe NMSs.
Basal Ganglia ; Brain ; Caudate Nucleus ; Cerebellar Nuclei ; Globus Pallidus ; Head ; Humans ; Iron* ; Magnetic Resonance Imaging ; Neuroimaging ; Parkinson Disease* ; Pars Compacta ; Pars Reticulata ; Pathology ; Putamen ; Red Nucleus

Animals ; Dopamine ; metabolism ; Dopaminergic Neurons ; metabolism ; Humans ; Iron ; metabolism ; Oxidative Stress ; Parkinson Disease ; metabolism ; Pars Compacta ; metabolism ; alpha-Synuclein ; metabolism

Parkinson disease (PD) is the second most prevalent neurodegenerative disorder after Alzheimer disease. The loss of specific brain area, the substantia nigra pars compacta is known as a major etiology, however it is not fully understood how this neurodegeneration is initiated and what precisely causes this disease. As one aspect of pathophysiology for PD, synaptic dysfunction (synaptopathy) is thought to be an earlier appearance for neurodegeneration. In addition, some of the familial factors cumulatively exhibit that these factors such as α-synuclein, leucine-rich repeat kinase 2, parkin, PTEN-induced kinase 1, and DJ-1 are involved in the regulation of synaptic function and missense mutants of familial factors found in PD-patient show dysregulation of synaptic functions. In this review, we have discussed the physiological function of these genetic factors in presynaptic terminal and how dysregulation of presynaptic function by genetic factors might be related to the pathogenesis of Parkinson disease.
Alzheimer Disease ; Brain ; Neurodegenerative Diseases ; Parkinson Disease* ; Pars Compacta ; Phosphotransferases ; Presynaptic Terminals ; Synapses ; Synaptic Transmission ; Synaptic Vesicles

Animals ; Behavior, Animal ; physiology ; Dopamine ; metabolism ; Dopaminergic Neurons ; physiology ; Humans ; Mice ; Motor Activity ; physiology ; Parkinson Disease ; metabolism ; physiopathology ; Pars Compacta ; physiopathology

Astrocyte is the most abundant cell type in the central nervous system and its importance has been increasingly recognized in the brain pathophysiology. To study in vivo function of astrocyte, astrocyte-specific gene-targeting is regarded as a powerful approach. Especially, hGFAP-CreERT2, which expresses tamoxifen-inducible Cre recombinase under the human GFAP promoter, has been developed and characterized from several research groups. However, one of these mouse lines, [Tg(GFAP-Cre/ERT2)13Kdmc] from Ken McCarthy group has not been quantitatively analyzed, despite its frequent use. Here, we performed comprehensive characterization of this mouse line with quantitative analysis. By crossing this mouse line with Ai14 (RCL-tdTomato), a very sensitive Cre reporter mouse line, we visualized the Cre-expressing cells in various brain regions. For quantitative analysis, we immunostained S100β as an astrocytic marker and NeuN, tyrosine hydroxylase or calbindin as a neuronal marker in different brain regions. We calculated ‘astrocyte specificity’ as the proportion of co-labelled S100β and tdTomato positive cells in the total number of tdTomato positive cells and the ‘astrocyte coverage’ as the proportion of co-labelled S100β and tdTomato positive cells in the total number of S100β positive cells. Interestingly, we found varying degree of astrocyte specificity and coverage in each brain region. In cortex, hypothalamus, substantia nigra pars compacta and cerebellar Purkinje layer, we observed high astrocyte specificity (over 89%) and relatively high astrocyte coverage (over 70%). In striatum, hippocampal CA1 layer, dentate gyrus and cerebellar granule layer, we observed high astrocyte specificity (over 80%), but relative low astrocyte coverage (50–60%). However, thalamus and amygdala showed low astrocyte specificity (about 65%) and significant neuron specificity (over 30%). This hGFAP-CreERT2 mouse line can be useful for genetic modulations of target gene either in gain-of-function or loss-of-function studies in the brain regions with high astrocyte specificity and coverage. However, the use of this mouse line should be restricted to gain-of-function studies in the brain regions with high astrocyte specificity but low coverage. In conclusion, hGFAP-CreERT2 mouse line could be a powerful tool for gene-targeting of astrocytes in cortex, striatum, hippocampus, hypothalamus, substantia nigra pars compacta and cerebellum, but not in thalamus and amygdala.
Amygdala ; Animals ; Astrocytes* ; Brain* ; Calbindins ; Central Nervous System ; Cerebellum ; Dentate Gyrus ; Hippocampus ; Humans ; Hypothalamus ; Mice* ; Neurons ; Pars Compacta ; Recombinases ; Sensitivity and Specificity* ; Thalamus ; Tyrosine 3-Monooxygenase

Transient receptor potential vanilloid subtype 1 (TRPV1) on astrocytes prevents ongoing degeneration of nigrostriatal dopamine (DA) neurons in MPP⁺-lesioned rats via ciliary neurotrophic factor (CNTF). The present study determined whether such a beneficial effect of astrocytic TRPV1 could be achieved after completion of injury of DA neurons, rather than ongoing injury, which seems more relevant to therapeutics. To test this, the MPP⁺-lesioned rat model utilized here exhibited approximately 70~80% degeneration of nigrostriatal DA neurons that was completed at 2 weeks post medial forebrain bundle injection of MPP⁺. TRPV1 agonist, capsaicin (CAP), was intraperitoneally administered. CNTF receptor alpha neutralizing antibody (CNTFRαNAb) was nigral injected to evaluate the role of CNTF endogenously produced by astrocyte through TRPV1 activation on DA neurons. Delayed treatment of CAP produced a significant reduction in amphetamine-induced rotational asymmetry. Accompanying this behavioral recovery, CAP treatment increased CNTF levels and tyrosine hydroxylase (TH) activity in the substantia nigra pars compacta (SNpc), and levels of DA and its metabolites in the striatum compared to controls. Interestingly, behavioral recovery and increases in biochemical indices were not reflected in trophic changes of the DA system. Instead, behavioral recovery was temporal and dependent on the continuous presence of CAP treatment. The results suggest that delayed treatment of CAP increases nigral TH enzyme activity and striatal levels of DA and its metabolites by CNTF endogenously derived from CAP-activated astrocytes through TRPV1, leading to functional recovery. Consequently, these findings may be useful in the treatment of DA imbalances associated with Parkinson's disease.
Animals ; Antibodies, Neutralizing ; Astrocytes ; Capsaicin ; Ciliary Neurotrophic Factor ; Dopamine ; Dopaminergic Neurons ; Medial Forebrain Bundle ; Models, Animal ; Neurons ; Parkinson Disease ; Pars Compacta ; Rats ; Receptor, Ciliary Neurotrophic Factor ; Tyrosine 3-Monooxygenase

Parkinson's disease is a neurodegenerative disease characterized by the progressive loss of dopaminergic neurons within the substantia nigra pars compacta. In the present study, we investigated whether β-Lapachone (β-LAP), a natural naphthoquinone compound isolated from the lapacho tree (Tabebuia avellanedae), elicits neuroprotective effects in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease mouse model. β-LAP reduced the tyrosine hydroxylase (TH)-immuno-reactive fiber loss induced by MPTP in the dorsolateral striatum, and alleviated motor dysfunction as determined by the rotarod test. In addition, β-LAP protected against MPTP-induced loss of TH positive neurons, and upregulated B-cell lymphoma 2 protein (Bcl-2) expression in the substantia nigra. Based on previous reports on the neuroprotective role of nuclear factor-E2-related factor-2 (Nrf2) in neurodegenerative diseases, we investigated whether β-LAP induces upregulation of the Nrf2-hemeoxygenae-1 (HO-1) signaling pathway molecules in MPTP-injected mouse brains. Western blot and immunohistochemical analyses indicated that β-LAP increased HO-1 expression in glial fibrillary acidic protein-positive astrocytes. Moreover, β-LAP increased the nuclear translocation and DNA binding activity of Nrf2, and the phosphorylation of upstream adenosine monophosphate-activated protein kinase (AMPK). β-LAP also increased the localization of p-AMPK and Nrf2 in astrocytes. Collectively, our data suggest that β-LAP exerts neuroprotective effect in MPTP-injected mice by upregulating the p-AMPK/Nrf2/HO-1 signaling pathways in astrocytes.
1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine ; Adenosine ; Animals ; Astrocytes ; Blotting, Western ; Brain ; DNA ; Dopaminergic Neurons ; Lymphoma, B-Cell ; Mice ; Neurodegenerative Diseases ; Neurons ; Neuroprotection ; Neuroprotective Agents ; Parkinson Disease ; Pars Compacta ; Phosphorylation ; Protein Kinases ; Rotarod Performance Test ; Substantia Nigra ; Trees ; Tyrosine 3-Monooxygenase ; Up-Regulation