Trial of Deferiprone in Parkinson's Disease.

BACKGROUND: Iron content is increased in the substantia nigra of persons with Parkinson's disease and may contribute to the pathophysiology of the disorder. Early research suggests that the iron chelator deferiprone can reduce nigrostriatal iron content in persons with Parkinson's disease, but its effects on disease progression are unclear. METHODS: We conducted a multicenter, phase 2, randomized, double-blind trial involving participants with newly diagnosed Parkinson's disease who had never received levodopa. Participants were assigned (in a 1:1 ratio) to receive oral deferiprone at a dose of 15 mg per kilogram of body weight twice daily or matched placebo for 36 weeks. Dopaminergic therapy was withheld unless deemed necessary for symptom control. The primary outcome was the change in the total score on the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS; range, 0 to 260, with higher scores indicating more severe impairment) at 36 weeks. Secondary and exploratory clinical outcomes at up to 40 weeks included measures of motor and nonmotor disability. Brain iron content measured with the use of magnetic resonance imaging was also an exploratory outcome. RESULTS: A total of 372 participants were enrolled; 186 were assigned to receive deferiprone and 186 to receive placebo. Progression of symptoms led to the initiation of dopaminergic therapy in 22.0% of the participants in the deferiprone group and 2.7% of those in the placebo group. The mean MDS-UPDRS total score at baseline was 34.3 in the deferiprone group and 33.2 in the placebo group and increased (worsened) by 15.6 points and 6.3 points, respectively (difference, 9.3 points; 95% confidence interval, 6.3 to 12.2; P<0.001). Nigrostriatal iron content decreased more in the deferiprone group than in the placebo group. The main serious adverse events with deferiprone were agranulocytosis in 2 participants and neutropenia in 3 participants. CONCLUSIONS: In participants with early Parkinson's disease who had never received levodopa and in whom treatment with dopaminergic medications was not planned, deferiprone was associated with worse scores in measures of parkinsonism than those with placebo over a period of 36 weeks. (Funded by the European Union Horizon 2020 program; FAIRPARK-II ClinicalTrials.gov number, NCT02655315.).

Measuring the iron content of dopaminergic neurons in substantia nigra with MRI relaxometry.

In Parkinson's disease, the depletion of iron-rich dopaminergic neurons in nigrosome 1 of the substantia nigra precedes motor symptoms by two decades. Methods capable of monitoring this neuronal depletion, at an early disease stage, are needed for early diagnosis and treatment monitoring. Magnetic resonance imaging (MRI) is particularly suitable for this task due to its sensitivity to tissue microstructure and in particular, to iron. However, the exact mechanisms of MRI contrast in the substantia nigra are not well understood, hindering the development of powerful biomarkers. In the present report, we illuminate the contrast mechanisms in gradient and spin echo MR images in human nigrosome 1 by combining quantitative 3D iron histology and biophysical modeling with quantitative MRI on post mortem human brain tissue. We show that the dominant contribution to the effective transverse relaxation rate (R2*) in nigrosome 1 originates from iron accumulated in the neuromelanin of dopaminergic neurons. This contribution is appropriately described by a static dephasing approximation of the MRI signal. We demonstrate that the R2* contribution from dopaminergic neurons reflects the product of cell density and cellular iron concentration. These results demonstrate that the in vivo monitoring of neuronal density and iron in nigrosome 1 may be feasible with MRI and provide directions for the development of biomarkers for an early detection of dopaminergic neuron depletion in Parkinson's disease.

A Pilot Study of Changes in the Level of Catecholamines and the Activity of α-2-Macroglobulin in the Tear Fluid of Patients with Parkinson's Disease and Parkinsonian Mice.

Development of differential and early (preclinical) diagnostics of Parkinson's disease (PD) is among the priorities in neuroscience. We searched for changes in the level of catecholamines and α-2-macroglobulin activity in the tear fluid (TF) in PD patients at an early clinical stage. It was shown that TF in patients is characterized by an increased level of noradrenaline mainly on the ipsilateral side of pronounced motor symptoms (72%, p = 0.049), a decreased level of adrenaline on both sides (ipsilateral-53%, p = 0.004; contralateral-42%, p = 0.02), and an increased α-2-macroglobulin activity on both sides (ipsilateral-53%, p = 0.03; contralateral-56%, p = 0.037) compared to controls. These changes are considered as potential biomarkers for differential diagnosis. Similar changes in the TF were found in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice when modeling clinical and preclinical stages of PD. These data show the adequacy of models to the pathogenesis of PD along the selected metabolic pathways, and also suggest that the found TF changes can be considered as potential biomarkers for preclinical diagnosis of PD. In Parkinsonian mice, the level of catecholamines also changes in the lacrimal glands, which makes it possible to consider them as one of the sources of catecholamines in the TF.

PEP-1-GLRX1 Reduces Dopaminergic Neuronal Cell Loss by Modulating MAPK and Apoptosis Signaling in Parkinson's Disease.

Parkinson's disease (PD) is characterized mainly by the loss of dopaminergic neurons in the substantia nigra (SN) mediated via oxidative stress. Although glutaredoxin-1 (GLRX1) is known as one of the antioxidants involved in cell survival, the effects of GLRX1 on PD are still unclear. In this study, we investigated whether cell-permeable PEP-1-GLRX1 inhibits dopaminergic neuronal cell death induced by 1-methyl-4-phenylpyridinium (MPP+) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). We showed that PEP-1-GLRX1 protects cell death and DNA damage in MPP+-exposed SH-SY5Y cells via the inhibition of MAPK, Akt, and NF-κB activation and the regulation of apoptosis-related protein expression. Furthermore, we found that PEP-1-GLRX1 was delivered to the SN via the blood-brain barrier (BBB) and reduced the loss of dopaminergic neurons in the MPTP-induced PD model. These results indicate that PEP-1-GLRX1 markedly inhibited the loss of dopaminergic neurons in MPP+- and MPTP-induced cytotoxicity, suggesting that this fusion protein may represent a novel therapeutic agent against PD.

Fast serotonin voltammetry as a versatile tool for mapping dynamic tissue architecture: I. Responses at carbon fibers describe local tissue physiology.

It is important to monitor serotonin neurochemistry in the context of brain disorders. Specifically, a better understanding of biophysical alterations and associated biochemical functionality within subregions of the brain will enable better of understanding of diseases such as depression. Fast voltammetric tools at carbon fiber microelectrodes provide an opportunity to make direct evoked and ambient serotonin measurements in vivo in mice. In this study, we characterize novel stimulation and measurement circuitries for serotonin analyses in brain regions relevant to psychiatric disease. Evoked and ambient serotonin in these brain areas, the CA2 region of the hippocampus and the medial prefrontal cortex, are compared to ambient and evoked serotonin in the substantia nigra pars reticulata, an area well established previously for serotonin measurements with fast voltammetry. Stimulation of a common axonal location evoked serotonin in all three brain regions. Differences are observed in the serotonin release and reuptake profiles between these three brain areas which we hypothesize to arise from tissue physiology heterogeneity around the carbon fiber microelectrodes. We validate this hypothesis mathematically and via confocal imaging. We thereby show that fast voltammetric methods can provide accurate information about local physiology and highlight implications for chemical mapping. Cover Image for this issue: doi: 10.1111/jnc.14739.

Region-Specific Characterization of N-Glycans in the Striatum and Substantia Nigra of an Adult Rodent Brain.

N-glycan alterations in the nervous system can result in different neuropathological symptoms such as mental retardation, seizures, and epilepsy. Studies have reported the characterization of N-glycans in rodent brains, but there is a lack of spatial resolution as either the tissue samples were homogenized or specific proteins were selected for analysis of glycosylation. We hypothesize that region-specific resolution of N-glycans isolated from the striatum and substantia nigra (SN) can give an insight into the establishment and pathophysiological degeneration of neural circuitry in Parkinson's disease. Specific objectives of the study include isolation of N-glycans from the rat striatum and SN; reproducibility, resolution, and relative quantitation of N-glycome using ultra-performance liquid chromatography (UPLC), weak anion exchange-UPLC, and lectin histochemistry. The total N-glycomes from the striatum and SN were characterized using database mining (GlycoStore), exoglycosidase digestions, and liquid chromatography-mass spectrometry. It revealed significant differences in complex and oligomannose type N-glycans, sialylation (mono-, di-, and tetra-), fucosylation (tri-, core, and outer arm), and galactosylation (di-, tri-, and tetra-) between striatum and SN N-glycans with the detection of phosphorylated N-glycans in SN which were not detected in the striatum. This study presents the most comprehensive comparative analysis of relative abundances of N-glycans in the striatum and SN of rodent brains, serving as a foundation for identifying "brain-type" glycans as biomarkers or therapeutic targets and their modulation in neurodegenerative disorders.

Testing alternatives: the use of adipose-derived mesenchymal stem cells to slow neurodegeneration in a rat model of Parkinson's disease.

Parkinson's disease (PD) is a chronic neurodegenerative disease. Unfortunately, the effectiveness of anti-Parkinson treatments gradually diminishes owing to the progressive degeneration of the dopaminergic terminals. The research described here investigated the effect of adipose-derived mesenchymal stem cells (AD-MSC) versus that of an anti-Parkinson drug in a rat model of Parkinsonism. Forty adult rats were divided into four equal groups, each group receiving a different treatment: vehicle, rotenone, rotenone + AD-MSC, or rotenone + carbidopa/levodopa. Behavioral tests were carried out before and at the end of the treatment and specimens harvested from the midbrain were processed for light and electron microscopy. Genetic expression of glial fibrillary acidic protein (GFAP) and Nestin mRNA was assessed. Expression of the Lamin-B1 and Vimentin genes was measured, along with plasma levels of Angiopoietin-2 and dopamine. Treatment with rotenone induced pronounced motor deficits, as well as neuronal and glial alterations. The AD-MSC group showed improvements in motor function in the live animals and in the microscopic picture presented by their tissues. The fold change of both genes (GFAP and Nestin) decreased significantly in the AD-MSC and carbidopa/levodopa groups compared to the group with Parkinson's disease. Plasma levels of Angiopoietin-2 and dopamine were significantly increased after treatment (P < 0.001) compared to levels in the rats with Parkinson's disease. AD-MSC reduced neuronal degeneration more efficiently than did the anti-Parkinson drug in a rat model of Parkinsonism.

NOP Receptor Ligands and Parkinson's Disease.

Nociceptin/Orphanin FQ (N/OFQ) and its NOP receptor are highly expressed in motor areas of the rodent, nonhuman, and human primate brain, such as primary motor cortex, thalamus, globus pallidus, striatum, and substantia nigra. Endogenous N/OFQ negatively regulates motor behavior and dopamine transmission through NOP receptors expressed by dopaminergic neurons of the substantia nigra compacta. Consistent with the existence of an N/OFQ tone over dopaminergic transmission, blockade of NOP receptor antagonists increases striatal dopamine release. In this chapter, we will review the evidence linking the N/OFQ-NOP receptor system to Parkinson's disease (PD). We will first discuss data showing that the central N/OFQ-NOP receptor system undergoes plastic changes in different basal ganglia nuclei following dopamine depletion. Then we will show that NOP receptor antagonists relieve motor deficits in different rodent and nonhuman primate models of PD. Mechanistically, NOP receptor blockade in substantia nigra reticulata results in rebalancing of the inhibitory GABAergic and excitatory glutamatergic inputs impinging on nigro-thalamic GABAergic neurons, leading to thalamic disinhibition. We will also present data showing that, in addition to motor symptoms, N/OFQ also plays a role in the parkinsonian neurodegeneration. In fact, NOP receptor antagonists possess neuroprotective/neurorescue properties in in vitro and in vivo models of PD.

Individual Variability of Protein Expression in Human Tissues.

Human tissues are known to exhibit interindividual variability, but a deeper understanding of the different factors affecting protein expression is necessary to further apply this knowledge. Our goal was to explore the proteomic variability between individuals as well as between healthy and diseased samples, and to test the efficacy of machine learning classifiers. In order to investigate whether disparate proteomics data sets may be combined, we performed a retrospective analysis of proteomics data from 9 different human tissues. These data sets represent several different sample prep methods, mass spectrometry instruments, and tissue health. Using these data, we examined interindividual and intertissue variability in peptide expression, and analyzed the methods required to build accurate tissue classifiers. We also evaluated the limits of tissue classification by downsampling the peptide data to simulate situations where less data is available, such as clinical biopsies, laser capture microdissection or potentially single-cell proteomics. Our findings reveal the strong potential for utilizing proteomics data to build robust tissue classifiers, which has many prospective clinical applications for evaluating the applicability of model clinical systems.

Specific visualization of neuromelanin-iron complex and ferric iron in the human post-mortem substantia nigra using MR relaxometry at 7T.

Neuromelanin (NM) is an endogenous iron chelating molecule of pigmented neurons in the human substantia nigra (SN). Along with the increase in iron deposition, the reduction in NM-containing dopaminergic neurons and the variation of iron load on NM are generally considered to be important factors participating to pathogenesis of Parkinson's disease (PD). The aim of this study was to non-invasively delineate the spatial distributions of paramagnetic magnetic susceptibility perturbers, such as NM-iron complex and ferric iron in SN. Multiple quantitative MR parameters of T1, T2, T2*, susceptibility weighted image (SWI), quantitative susceptibility map (QSM), and T1 weighted image with magnetization transfer (MT) effects were acquired for six post-mortem SN samples without a history of neurological disease. Co-registered quantitative histological validations were performed to identify and correlate NM pigments, iron deposits, and myelin distributions with respect to associated MR parameters. The regions with NM pigments and iron deposits showed positive magnetic susceptibility (paramagnetic) values, while myelinated areas showed negative magnetic susceptibility (diamagnetic) values from the QSM. The region of reduced T2 values in SN mostly coincided with high iron deposits, but not necessarily with the NM pigments. The correlations between T2*/T2 (or T2*/T22) values and NM pigments were higher than those between T2* values and NM pigments, due to the effective size differences between NM-iron complex and ferric iron. Consequently, separate segmentations of ferric iron from the T2 map and NM-iron complex from the T2*/T2 map (or T2*/T22 map) were possible with the boundary of the SN determined from the T1 weighted image.

The synthesis and characterization of glutathione-modified superparamagnetic iron oxide nanoparticles and their distribution in rat brains after injection in substantia nigra.

Glutathione-modified superparamagnetic iron oxide nanoparticles (GSH-SPIONs) were prepared by conjugating glutathione (GSH) on the surface of the PEG (Polyethylene glycol)/PEI (polyethyleneimine)-SPIONs which were synthesized by thermal decomposition method. Thermogravimetric analysis showed that the mass fraction of GSH on the surface of SPIONs was 30.64 wt%. GSH-SPIONs in PBS were injected into the substantia nigra of rat brains. The subcellular distributions of the nanoparticles in the brains was examined by the transmission electron microscope (TEM). A remarkable amount of GSH-SPIONs were found in vesicles inside cell bodies and axons, and in mitochondria. TEM pictures show that GSH-SPIONs enter the neuronal cells by endocytosis and travel through axoplasmic transport. GSH-SPIONs have great potential as drug delivery agents in the brain to treat diseases or study brain function via mitochondria-targeting way or axoplasmic transport way.

[Neurochemical and morphological changes of microstructures of the compact part of the substantia nigra of human brain in aging and Parkinson's disease (literature review).]

For investigation of pathogenetic patterns of Parkinson's disease, it is important to adequately assess the mechanisms of age-related involution and morphological changes that are formed in the brain during this process. Clinical symptoms, detected in Parkinson's disease (rigidity, hypokinesia, tremor), indicate the involvement in the pathological process of nigrostriate brain formations due to the death of dopamine neurons in the compact part of the substantia nigra. At the same time, the loss of these neurons, as well as the change in the number of neuroglia cells in the substantia nigra of the brain, are detected not only in Parkinson's disease, but also in physiological aging. This review presents and compares data on the morphological changes in the compact part of the substantia nigra of the human brain in physiological aging and Parkinson's disease.

Contrast mechanisms associated with neuromelanin-MRI.

PURPOSE: To investigate the physical mechanisms associated with the contrast observed in neuromelanin MRI. METHODS: Phantoms having different concentrations of synthetic melanins with different degrees of iron loading were examined on a 3 Tesla scanner using relaxometry and quantitative magnetization transfer (MT). RESULTS: Concentration-dependent T1 and T2 shortening was most pronounced for the melanin pigment when combined with iron. Metal-free melanin had a negligible effect on the magnetization transfer spectra. On the contrary, the presence of iron-laden melanins resulted in a decreased magnetization transfer ratio. The presence of melanin or iron (or both) did not have a significant effect on the macromolecular content, represented by the pool size ratio. CONCLUSION: The primary mechanism underlying contrast in neuromelanin-MRI appears to be the T1 reduction associated with melanin-iron complexes. The macromolecular content is not significantly influenced by the presence of melanin with or without iron, and thus the MT is not directly affected. However, as T1 plays a role in determining the MT-weighted signal, the magnetization transfer ratio is reduced in the presence of melanin-iron complexes. Magn Reson Med 78:1790-1800, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Isoforms of the Erythropoietin receptor in dopaminergic neurons of the Substantia Nigra.

Erythropoietin receptor (EpoR) regulates erythrocytes differentiation in blood. In the brain, EpoR has been shown to protect several neuronal cell types from cell death, including the A9 dopaminergic neurons (DA) of the Substantia Nigra (SN). These cells form the nigrostriatal pathway and are devoted to the control of postural reflexes and voluntary movements. Selective degeneration of A9 DA neurons leads to Parkinson's disease. By the use of nanoCAGE, a technology that allows the identification of Transcription Start Sites (TSSs) at a genome-wide level, we have described the promoter-level expression atlas of mouse A9 DA neurons purified with Laser Capture Microdissection (LCM). Here, we identify mRNA variants of the Erythropoietin Receptor (DA-EpoR) transcribed from alternative TSSs. Experimental validation and full-length cDNA cloning is integrated with gene expression analysis in the FANTOM5 database. In DA neurons, the EpoR gene encodes for a N-terminal truncated receptor. Based on STAT5 phosphorylation assays, we show that the new variant of N-terminally truncated EpoR acts as decoy when co-expressed with the full-length form. A similar isoform is also found in human. This work highlights new complexities in the regulation of Erythropoietin (EPO) signaling in the brain.

Drug-induced Parkinsonism versus Idiopathic Parkinson Disease: Utility of Nigrosome 1 with 3-T Imaging.

Purpose To explore the utility of nigrosome 1 with 3-T magnetic resonance (MR) imaging to differentiate idiopathic Parkinson disease (IPD) from drug-induced parkinsonism (DIP). Materials and Methods The institutional review board approved this study, and participants gave informed consent. This study enrolled patients with DIP (n = 20) and IPD (n = 29) who underwent N-3-fluoropropyl-2-ß-carbomethoxy-3-ß-(4-iodophenyl)nortropane ((18)F-FP-CIT) positron emission tomography (PET) and healthy participants (n = 20). All participants underwent 0.5 × 0.5 × 1.0 mm(3) oblique axial three-dimensional multiecho-data image combination imaging to view the nigrosome 1 with 3-T imaging. Two reviewers independently assessed the nigrosome 1 without clinical information. DIP was diagnosed when no abnormality was seen at (18)F-FP-CIT PET. Diagnostic sensitivity, specificity, and accuracy of the nigrosome 1 imaging were evaluated between the IPD and DIP patients and between the IPD patients and healthy participants. Interrater agreement was assessed with Cohen κ. Results Both reviewers agreed in 63 of 69 participants (91.3%) for the presence of any abnormality on either side of the nigrosome 1 (κ = 0.825). Findings in all 29 IPD patients (100%) and three of 20 DIP patients (15%) were rated as abnormal and in 17 of 20 DIP patients (85%) they were interpreted as normal on the basis of imaging of the nitgrosome 1 (sensitivity, 100% (29 of 29); specificity, 85.0% (17 of 20); accuracy, 93.9% (46 of 49) between IPD and DIP patients). Findings in 3 of 20 healthy participants (15.0%) were interpreted as abnormal on the basis of imaging the nigrosome 1 while in the other 17 of 20 healthy participants (85.0%) they were rated as normal (sensitivity, 100% [29 of 29]; specificity, 85.0% [17 of 20]; accuracy, 93.9% [46 of 49] between IPD patients and healthy participants [κ = 0.831]). Conclusion The imaging of nigrosome 1 with 3-T imaging can differentiate DIP from IPD with high accuracy and may help to screen patients who need dopamine transporter imaging in those suspected of having DIP. (©) RSNA, 2015 Online supplemental material is available for this article.

Proton MR Spectroscopy for Monitoring Pathologic Changes in the Substantia Nigra and Globus Pallidus in Parkinson Disease.

OBJECTIVE: This retrospective study aimed to examine the relationship between the ratio of N-acetyl aspartate (NAA) to creatine in the substantia nigra (SN) and globus pallidus (GP) and the Hoehn-Yahr stage and Unified Parkinson Disease Rating Scale (UPDRS) score determined for patients with Parkinson disease (PD). MATERIALS AND METHODS: Thirty patients with PD who underwent proton MR spectroscopy ((1)H-MRS) and for whom a Hoehn-Yahr stage and a UPDRS score for PD were determined were retrospectively reviewed. Hydrogen-1-MRS was used to measure the metabolite levels in the bilateral SN and GP. RESULTS: The mean (± SD) age of the patients was 67.7 (± 10.6) years. The mean UPDRS score was 40.5 ± 13.9. Fourteen patients had PD of Hoehn-Yahr stages 1-2, and 16 patients had PD of Hoehn-Yahr stages 3-5. The NC ratio (the NAA-to-creatine ratio for the initially symptomatic side or the body divided by the NAA-to-creatine ratio for the contralateral side) for the bilateral GP (BGPNC) was significantly lower in the patients with stages 1-2 PD than in the patients with stages 3-5 PD (0.68 ± 0.23 vs 0.84 ± 0.11; p = 0.023). The NAA-to-creatine ratio for the initially symptomatic side of the SN was negatively correlated with the UPDRS score (r = -0.379; p = 0.039). CONCLUSION: In early PD, the changes in the GP are more pronounced on the side affected at the onset of PD, which may contribute to the development of asymmetric symptoms and signs. Hydrogen-1-MRS shows promise as a modality for evaluating PD.

Correlation of 3D FLAIR and Dopamine Transporter Imaging in Patients With Parkinsonism.

OBJECTIVE: The purpose of this study is to evaluate direct in vivo visualization of nigrosome-1 in substantia nigra (SN) with 3D FLAIR imaging and its diagnostic value in predicting the intactness of presynaptic dopaminergic function of the nigrostriatal pathway. MATERIALS AND METHODS: Forty-five patients showing parkinsonism who underwent both 3D FLAIR and dopamine transporter (DAT) imaging were recruited. In total, 90 SNs were reviewed on axial 3D FLAIR images. We regarded oval or linear hyperintensities on the posterolateral side of SN as intact nigrosome-1. Two neuroradiologists independently evaluated the appearance of nigrosome-1, and disagreements were settled by consensus. Kappa values for interrater agreement were calculated. Diagnostic performances of the appearance of nigrosome-1 for predicting presynaptic dopaminergic function on DAT imaging and Parkinson disease (PD) were calculated. RESULTS: The diagnostic performances of a loss of nigrosome-1 on 3D FLAIR images were sensitivity of 85.7%, specificity of 85.4%, positive predictive value (PPV) of 83.7%, and negative predictive value (NPV) of 87.2% for predicting impaired presynaptic dopaminergic function on DAT imaging, and sensitivity of 94.7%, specificity of 76.9%, PPV of 85.7%, and NPV of 90.9% for predicting PD. When only oval hyperintensity was considered as intact nigrosome-1, its sensitivity and NPV were increased up to 95.2% and 91.7%, respectively, for predicting impaired presynaptic dopaminergic function on DAT imaging, and both increased to 100% for predicting PD. Interobserver agreement for the appearance of nigrosome-1 on 3D FLAIR images was substantial (κ = 0.625). CONCLUSION: Nigrosome-1 could be visualized on 3D FLAIR images, and its loss can be used to predict presynaptic dopaminergic function and to diagnose PD with high accuracy.

Quantitative assessment of iron deposition in Parkinson's disease using enhanced T2 star-weighted angiography.

BACKGROUND: It has been reported that R2* is a sensitive marker for iron deposition. The aim of this study was to quantitatively assess iron deposition in Parkinson's disease (PD) using changes of R2* in enhanced T2 star-weighted angiography (ESWAN) and to discuss the value of ESWAN for PD. METHODS: Fifty-four primary PD patients and twenty-eight healthy individuals were examined by ESWAN in the 3·0 T magnetic resonance imaging system. The R2* values were measured from the deep gray nuclei (including the substantia nigra [SN], red nuclei, globus pallidus, putamina, caudate nuclei, and thalami). The unified PD rating scale (UPDRS) III assessment, the nonmotor symptoms scale (NMSS), and the mini mental state examination (MMSE) were used to rate all the patients. RESULTS: The comparison of the R* values between the deep gray nuclei on the same side of the PD patients and the control group revealed significant differences in the SN and red nuclei (P < 0.05). There was a significant difference between Hoehn and Yahr (HY) 1 and HY2-4 patients in terms of the values of the SN. There was a slight correlation between the R* values of the SN of the PD patients (HY >1) and the UPDRS III ratings. No correlation between the R* signal values in the PD patients and the NMSS and MMSE scales was found. CONCLUSION: Iron concentrations in the regions of interest may represent the severity of the PD motor symptoms, and whether they are related to the nonmotor symptoms remains a question for further investigation. ESWAN offers special advantages in determining iron depositions in the brain and in enabling a sensitive diagnosis of PD, although further study is necessary.

ser31 Tyrosine hydroxylase phosphorylation parallels differences in dopamine recovery in nigrostriatal pathway following 6-OHDA lesion.

Compensatory mechanisms in dopamine (DA) signaling have long been proposed to delay onset of locomotor symptoms during Parkinson's disease progression until ~ 80% loss of striatal DA occurs. Increased striatal dopamine turnover has been proposed to be a part of this compensatory response, but may occur after locomotor symptoms. Increased tyrosine hydroxylase (TH) activity has also been proposed as a mechanism, but the impact of TH protein loss upon site-specific TH phosphorylation in conjunction with the impact on DA tissue content is not known. The tissue content of DA was determined against TH protein loss in the striatum and substantia nigra (SN) following 6-hydroxydopamine lesion in the medial forebrain bundle in young Sprague-Dawley male rats. Although DA predictably decreased in both regions following 6-hydroxydopamine, there was a significant difference in DA loss between the striatum (75%) and SN (40%), despite similar TH protein loss. Paradoxically, there was a significant decrease in DA against remaining TH protein in striatum, but a significant increase in DA against remaining TH in SN. In the SN, increased DA per remaining TH protein was matched by increased ser31, but not ser40, TH phosphorylation. In striatum, both ser31 and ser40 phosphorylation decreased, reflecting decreased DA per TH. However, in control nigral and striatal tissue, only ser31 phosphorylation correlated with DA per TH protein. Combined, these results suggest that the phosphorylation of ser31 in the SN may be a mechanism to increase DA biosynthesis against TH protein loss in an in vivo model of Parkinson's disease. Properties of dopamine biosynthesis were evaluated in the 6-OHDA model of Parkinson's disease by studying the impact of tyrosine hydroxylase (TH) protein loss on its own phosphorylation and dopamine (DA) tissue content in rat nigrostriatal pathway. A dichotomous response was observed between striatum and substantia nigra in that dopamine per remaining TH decreased in striatum, but increased in substantia nigra. Phosphorylation at ser31 reflected these differences, indicating that ser31 phosphorylation may be critical to maintain dopamine with progressive TH protein loss. Drawings are from slides purchased from Motifolio (http://motifolio.com/).

Reduction of the nitro group to amine by hydroiodic acid to synthesize o-aminophenol derivatives as putative degradative markers of neuromelanin.

Neuromelanin (NM) is produced in dopaminergic neurons of the substantia nigra (SN) and in noradrenergic neurons of the locus coeruleus (LC). The synthesis of NM in those neurons is a component of brain aging and there is the evidence that this pigment can be involved in the pathogenesis of neurodegenerative diseases such as Parkinson's disease. NM is believed to derive from the oxidative polymerization of dopamine (DA) or norepinephrine (NE) with the participation of cysteine, dolichols and proteins. However, there are still unknown aspects in the chemical structure of NM from SN (SN-NM) and LC (LC-NM). In this study, we designed a new method to synthesize o-aminophenol compounds as putative degradation products of catecholamines and their metabolites which may be incorporated into NM. Those compounds are aminohydroxyphenylethylamine (AHPEA) isomers, aminohydroxyphenylacetic acid (AHPAA) isomers and aminohydroxyethylbenzene (AHEB) isomers, which are expected to arise from DA or NE, 3,4-dihydroxyphenylacetic acid (DOPAC) or 3,4-dihydroxyphenylmandelic acid (DOMA) and 3,4-dihydroxyphenylethanol (DOPE) or 3,4-dihydroxyphenylethyleneglycol (DOPEG), respectively. These o-aminophenol compounds were synthesized by the nitration of phenol derivatives followed by reduction with hydroiodic acid (HI), and they could be identified by HPLC in HI hydrolysates of SN-NM and LC-NM. This degradative approach by HI hydrolysis allows the identification of catecholic precursors unique to SN-NM and LC-NM, which are present in catecholaminergic neurons.