Disease Substantia Nigra Research Articles

Glia maturation factor levels are elevated in the striatum and substantia nigra in Parkinson's disease

Glia maturation factor (GMF) is an inflammatory protein, discovered in our laboratory, plays a major role in the pathogenesis of CNS inflammatory diseases. Although GMF has been implicated as a major contributing factor in the pathogenesis of EAE, an animal model of Multiple Sclerosis, there has not been a direct demonstration of GMF expression in human PD brains. In the present study we demonstrate a significant up regulation of GMF expression in human PD brain. Human brain tissues were obtained from autopsy, with PMI less than 6 h, at UI Deeded Body Program. For the comparison, we examined brain tissue from cases with clinically diagnosed and neuropathologically confirmed Parkinson's disease and age‐matched non‐PD controls. Our results show degenerating TH‐ immunostained neurons/ fibers associated with activated microglia and astrocytes in the autopsied brain from PD case. In PD brain, GMF appears to be localized to activated astrocytes and dopaminergic neurons. Additionally, we quantitatively estimated GMF protein by ELISA in different regions of PD brains. We demonstrated a significant increase (over 10 fold) in GMF levels in the substantia nigra and striatum of human PD brains compare to non‐PD. Thus, our results provide strong evidence that under conditions of neurodegeneration in PD the expression of GMF is significantly upregulated. (Supported by VA Merit Review award and NINDS grant NS073670).

Dopamine receptor D3 expressed on CD4+ T-cells favours neurodegeneration of dopaminergic neurons during Parkinson's disease

Event Abstract Back to Event Dopamine receptor D3 expressed on CD4+ T-cells favours neurodegeneration of dopaminergic neurons during Parkinson's disease Rodrigo Pacheco1, 2*, Hugo Gonzalez1, 3, Francisco Contreras1, 3, Carolina Prado1, 3, Daniela Elgueta1 and Dafne Franz1 1 Fundacion Ciencia & Vida, Chile 2 Universidad San Sebastian, Chile 3 Universidad Andres Bello, Chile Emerging evidence has demonstrated that CD4+ T-cells infiltrate into the substantia nigra (SN) in Parkinson's disease (PD) patients and in animal models of PD. SN-infiltrated CD4+ T-cells bearing inflammatory phenotypes promote microglial activation and strongly contribute to neurodegeneration of dopaminergic neurons. Importantly, altered expression of dopamine receptor D3 (D3R) in peripheral blood lymphocytes from PD patients has been correlated with disease severity. Moreover, pharmacological evidence has suggested that D3R is involved in IFN-gamma production by human CD4+ T-cells. Here, we studied the role of D3R expressed on CD4+ T-cells in neurodegeneration of dopaminergic neurons in the SN using a mouse-model of PD. Our results show that D3R-deficient mice are strongly protected against loss of dopaminergic neurons and microglial activation during 1- methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD. Notably, D3R-deficient mice become susceptible to MPTPinduced neurodegeneration and microglial activation upon transfer of wild-type (WT) CD4+ T-cells. Furthermore, RAG1 knockout mice, which are devoid of T-cells and are resistant to MPTP-induced neurodegeneration, become susceptible to MPTP-induced loss of dopaminergic neurons when reconstituted with WT CD4+ T-cells but not when transferred with D3R-deficient CD4+ T-cells. In agreement, experiments analyzing activation and differentiation of CD4+ T-cells revealed that D3R favours both T-cell activation and acquisition of the Th1 inflammatory phenotype. These findings indicate that D3R expressed on CD4+ T-cells plays a fundamental role in the physiopathology of MPTP-induced PD in a mouse model (1). Acknowledgements This study was supported by grants: FONDECYT 1130271 (from CONICYT), PFB-16 (from CONICYT), 2011-0001-R (from Universidad San Sebastian).

Neuromelanins of Human Brain Have Soluble and Insoluble Components with Dolichols Attached to the Melanic Structure

Neuromelanins (NMs) are neuronal pigments of melanic-lipidic type which accumulate during aging. They are involved in protective and degenerative mechanisms depending on the cellular context, however their structures are still poorly understood. NMs from nine human brain areas were analyzed in detail. Elemental analysis led to identification of three types of NM, while infrared spectroscopy showed that NMs from neurons of substantia nigra and locus coeruleus, which selectively degenerate in Parkinson’s disease, have similar structure but different from NMs from brain regions not targeted by the disease. Synthetic melanins containing Fe and bovine serum albumin were prepared to model the natural product and help clarifying the structure of NMs. Extensive nuclear magnetic resonance spectroscopy studies showed the presence of dolichols both in the soluble and insoluble parts of NM. Diffusion measurements demonstrated that the dimethyl sulfoxide soluble components consist of oligomeric precursors with MWs in the range 1.4–52 kDa, while the insoluble part contains polymers of larger size but with a similar composition. These data suggest that the selective vulnerability of neurons of substantia nigra and locus coeruleus in Parkinson’s disease might depend on the structure of the pigment. Moreover, they allow to propose a pathway for NM biosynthesis in human brain.

“Untangling” the relationship between Alzheimer disease and dementia with Lewy bodies

Lewy bodies, protein aggregations classically associated with Parkinson disease (PD) substantia nigra neurons, are not limited to the brainstem.1 Over time, pathologists developed terms such …

A yeast two‐hybrid screen reveals that osteopontin associates with MAP1A and MAP1B in addition to other proteins linked to microtubule stability, apoptosis and protein degradation in the human brain

Osteopontin (OPN) expression is reduced in surviving dopaminergic neurones in the substantia nigra (SN) in Parkinson's disease (PD), and protects against MPP(+) -induced cell death in primary mesencephalic cultures and 6-OHDA-induced cell loss in the rat, while inactivation of OPN aggravates cell death. OPN is thought to act through interactions with integrin receptors or CD44. However, the specific protein interactions involved in OPN-mediated neuroprotection are unknown and are the focus of this study. The yeast two-hybrid (YTH) technique was utilised to investigate OPN-protein interactions, using full-length human OPN to screen a human foetal brain cDNA library. Proteins involved in apoptosis, protein degradation and microtubule stability were identified as OPN binding partners. These included: MAP1A and MAP1B, which regulate microtubule stability; RNF138, an E3 ubiquitin-ligase; proteasome β1 subunit, a subunit of the 20S proteasome involved in the ubiquitin-dependent cleavage of peptides; BAG6, SGTΑ and EF1A, proteins implicated in control of apoptosis; DnaJB1, a co-chaperone of Hsp70s; and pleiotrophin, a growth factor. The use of site-directed mutagenesis to modify known OPN protein binding sites outside the RGD integrin binding domain, specifically Y165A and D139E, inhibited some of these interactions. Further investigation using affinity pull-down assays, co-immunoprecipitation and immunohistochemistry confirmed that OPN associates with MAP1A and MAP1B in rat SN and striatum. These findings indicate a role for OPN in the regulation of microtubule dynamics, apoptosis and proteolysis in the brain, suggesting that OPN may act as an endogenous multifunctional protective protein in PD.

Asymmetrical diffusion tensor imaging indices of the rostral substantia nigra in Parkinson's disease

ObjectiveMotor asymmetry in Parkinson's disease (PD) is evident clinically and on functional neuroimaging, but not reported in diffusion tensor imaging (DTI). We aim to determine if asymmetry in fractional anisotropy (FA) and apparent diffusion coefficient (ADC) can be detected in the substantia nigra (SN) of PD subjects. MethodsDTI scans were performed on 11 PD and 12 healthy subjects. Regions of interest (ROIs) were drawn by 2 independent raters at the caudal, middle and rostral SN on each side. FA and ADC were extracted from the ROIs. ResultsSignificant asymmetry was observed in the FA (p < 0.005) and ADC (p < 0.00005) at the rostral SN of PD subjects. The differences in FA and ADC across the left and right rostral SN were significantly different between PD and healthy subjects, p < 0.05 and p < 0.02 respectively. PD subjects had significantly higher ADC at the left rostral SN than healthy subjects (p < 0.01). Significant correlation between the Unified Parkinson's Disease Rating Scale (UPDRS) motor scores and the FA was noted in the left rostral SN (r = 0.7, p < 0.03). ConclusionsAsymmetry in DTI indices was noted at the rostral SN of PD subjects. The relationship between FA in the SN and UPDRS motor score was studied. Our findings may provide a model for better understanding of the implication of FA reduction in the SN.

Magnetic resonance imaging of the substantia nigra in Parkinson's disease

Until recently, conventional magnetic resonance imaging (MRI) was most often negative in Parkinson's disease or showed nonspecific findings. Recent developments in structural MRI, including relaxometry, magnetization transfer, and neuromelanin imaging, have demonstrated improved contrast and enabled more accurate visualization of deep brain nuclei, in particular, the substantia nigra. Meanwhile, diffusion imaging has provided useful biomarkers of substantia nigra degeneration, showing reduced anisotropy and anatomical connectivity with the striatum and thalamus. These advances in structural imaging are complemented by findings of magnetic resonance spectroscopy on brain metabolism and resting-state functional MRI on functional connectivity. This article presents an overview of these new structural, metabolic, and resting-state functional MRI techniques and their implications for Parkinson's disease. The techniques are reviewed in the context of their potential for better understanding the disease in terms of diagnosis and pathophysiology and as biomarkers of its progression.

Different Signals of Magnetic Resonance Imaging and Ultrasound from Substantia Nigra in Parkinson's Disease and Control - Is Iron the Cause?

Different Signals of Magnetic Resonance Imaging and Ultrasound from Substantia Nigra in Parkinson's Disease and Control - Is Iron the Cause?

Tau deficiency induces parkinsonism with dementia by impairing APP-mediated iron export

The microtubule-associated protein tau has risk alleles for both Alzheimer's disease and Parkinson's disease and mutations that cause brain degenerative diseases termed tauopathies. Aggregated tau forms neurofibrillary tangles in these pathologies, but little is certain about the function of tau or its mode of involvement in pathogenesis. Neuronal iron accumulation has been observed pathologically in the cortex in Alzheimer's disease, the substantia nigra (SN) in Parkinson's disease and various brain regions in the tauopathies. Here we report that tau-knockout mice develop age-dependent brain atrophy, iron accumulation and SN neuronal loss, with concomitant cognitive deficits and parkinsonism. These changes are prevented by oral treatment with a moderate iron chelator, clioquinol. Amyloid precursor protein (APP) ferroxidase activity couples with surface ferroportin to export iron, but its activity is inhibited in Alzheimer's disease, thereby causing neuronal iron accumulation. In primary neuronal culture, we found loss of tau also causes iron retention, by decreasing surface trafficking of APP. Soluble tau levels fall in affected brain regions in Alzheimer's disease and tauopathies, and we found a similar decrease of soluble tau in the SN in both Parkinson's disease and the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model. These data suggest that the loss of soluble tau could contribute to toxic neuronal iron accumulation in Alzheimer's disease, Parkinson's disease and tauopathies, and that it can be rescued pharmacologically.

Changes in Selenoprotein P in Substantia Nigra and Putamen in Parkinson's Disease

Oxidative stress and oxidized dopamine contribute to the degeneration of the nigrostriatal pathway in Parkinson's disease (PD). Selenoproteins are a family of proteins containing the element selenium in the form of the amino acid selenocysteine, and many of these proteins have antioxidant functions. We recently reported changes in expression of the selenoprotein, phospholipid hydroperoxide glutathione peroxidase GPX4 and its co-localization with neuromelanin in PD brain. To further understand the changes in GPX4 in PD, we examine here the expression of the selenium transport protein selenoprotein P (Sepp1) in postmortem Parkinson's brain tissue. Sepp1 in midbrain was expressed in neurons of the substantia nigra (SN), and expression was concentrated within the centers of Lewy bodies, the pathological hallmark of PD. As with GPX4, Sepp1 expression was significantly reduced in SN from PD subjects compared with controls, but increased relative to cell density. In putamen, Sepp1 was found in cell bodies and in dopaminergic axons and terminals, although levels of Sepp1 were not altered in PD subjects compared to controls. Expression levels of Sepp1 and GPX4 correlated strongly in the putamen of control subjects but not in the putamen of PD subjects. These findings indicate a role for Sepp1 in the nigrostriatal pathway, and suggest that local release of Sepp1 in striatum may be important for signaling and/or synthesis of other selenoproteins such as GPX4.

High resolution magnetic susceptibility mapping of the substantia nigra in Parkinson's disease

To determine if tissue magnetic susceptibility is a more direct marker of tissue iron content than other MR markers of iron. This study presents the first quantitative, in vivo measurements of the susceptibility of the substantia nigra in patients with Parkinson's disease. Nine patients and 11 controls were studied at 7 Tesla. Susceptibility maps were created by inverting the filtered phase maps associated with T2* weighted images. On average, patients showed an increase in susceptibility of the pars compacta compared with controls, which correlates with the predicted increase in brain iron in Parkinson's disease. A rostral-caudal gradient in susceptibility was also observed in controls and patients. Susceptibility mapping may provide a new tool for studying the development of Parkinson's disease.

Combined R2* and Diffusion Tensor Imaging Changes in the Substantia Nigra in Parkinson's Disease

Recent magnetic resonance imaging studies suggest an increased transverse relaxation rate and reduced diffusion tensor imaging fractional anisotropy values in the substantia nigra in Parkinson's disease. The transverse relaxation rate and fractional anisotropy changes may reflect different aspects of Parkinson's disease-related pathological processes (ie, tissue iron deposition and microstructure disorganization). This study investigated the combined changes of transverse relaxation rate and fractional anisotropy in the substantia nigra in Parkinson's disease. High-resolution magnetic resonance imaging (T2-weighted, T2*, and diffusion tensor imaging) were obtained from 16 Parkinson's disease patients and 16 controls. Bilateral substantia nigras were delineated manually on T2-weighted images and coregistered to transverse relaxation rate and fractional anisotropy maps. The mean transverse relaxation rate and fractional anisotropy values in each substantia nigra were then calculated and compared between Parkinson's disease subjects and controls. Logistic regression, followed by receiver operating characteristic curve analysis, was employed to investigate the sensitivity and specificity of the combined measures for differentiating Parkinson's disease subjects from controls. Compared with controls, Parkinson's disease subjects demonstrated increased transverse relaxation rate (P<.0001) and reduced fractional anisotropy (P=.0365) in the substantia nigra. There was no significant correlation between transverse relaxation rate and fractional anisotropy values. Logistic regression analyses indicated that the combined use of transverse relaxation rate and fractional anisotropy values provides excellent discrimination between Parkinson's disease subjects and controls (c-statistic=0.996) compared with transverse relaxation rate (c-statistic=0.930) or fractional anisotropy (c-statistic=0.742) alone. This study shows that the combined use of transverse relaxation rate and fractional anisotropy measures in the substantia nigra of Parkinson's disease enhances sensitivity and specificity in differentiating Parkinson's disease from controls. Further studies are warranted to evaluate the pathophysiological correlations of these magnetic resonance imaging measurements and their effectiveness in assisting in diagnosing Parkinson's disease and following its progression.

Dietary intake of metals and risk of Parkinson's disease: A case-control study in Japan

Metals are involved in several important functions in the nervous system. Zinc and iron are increased and copper is decreased in the substantia nigra in Parkinson's disease (PD). However, epidemiological evidence for the association of dietary intake of metals with the risk of PD is limited. We investigated the relationship between metal consumption and the risk of PD in Japan using data from a multicenter hospital-based case-control study. Included were 249 cases within 6 years of onset of PD based on the UK PD Society Brain Bank clinical diagnostic criteria. Controls were 368 inpatients and outpatients without a neurodegenerative disease. Information on dietary factors was collected using a self-administered diet history questionnaire. Higher intake of iron, magnesium, and zinc was independently associated with a reduced risk of PD: the adjusted OR in the highest quartile was 0.24 (95% CI: 0.10–0.57, P for trend = 0.0003) for iron, 0.33 (95% CI: 0.13–0.81, P for trend = 0.007) for magnesium and 0.50 (95% CI: 0.26–0.95, P for trend = 0.055) for zinc. There were no relationships between the intake of copper or manganese and the risk of PD. Higher intake of iron, magnesium, and zinc may be protective against PD.

Combined R2* and Diffusion Tensor Imaging Changes in the Substantia Nigra in Parkinson's Disease

Combined R2* and Diffusion Tensor Imaging Changes in the Substantia Nigra in Parkinson's Disease

Parkinson's disease involves autophagy and abnormal distribution of cathepsin L

Accumulating evidences suggest that the related autophagy-lysosomal mechanism plays a critical role in many neurodegenerative disorders. In this study, we examined postmortem Parkinson's disease (PD) substantia nigra for evidence of cathepsin L by immunofluorescent staining, and found increased expression of cathepsin L in dopamine neurons of PD patients. We confirmed 6-OHDA induced nuclear translocation of cathepsin L in rat substantia nigral neurons as well. Furthermore, we observed autophagic vacuoles and lysosomes were accumulated in the 6-hydroxydopamine (6-OHDA) injured rat substantia nigra neurons with electron microscopy. Immunofluorescent staining showed that LC3 was enriched in dopamine neurons after 6-OHDA treatment. When pretreated with 3-methyladenine (3-MA), dopaminergic neurons were protected from cell death induced by 6-OHDA, associated with the suppression of LC3 and cathepsin L. Our results demonstrate that activation of autophagy and abnormal distribution of cathepsin L may be responsible for dopamine neuron death, involved in the pathogenic cascade event for the development of Parkinson's disease.

PATH53 Magnetic susceptibility of substantia nigra in Parkinson's disease: a 7-T in vivo MRI study

At post mortem, the hypopigmented substantia nigra (SN) of Parkinson disease (PD) patients generally shows a decrease in neuromelanin (NM) with an increase in ferritin particularly in dopaminergic neurones. Relaxometry-based...

Neurosteroid Biosynthetic Pathway Changes in Substantia Nigra and Caudate Nucleus in Parkinson's Disease

There is emerging evidence from animal studies for a neuroprotective role of sex steroids in neurodegenerative diseases, but studies in human brain are lacking. We have carried out an extensive study of the neurosteroid biosynthetic pathways in substantia nigra (SN), caudate nucleus (CN) and putamen (PU) of 7 Parkinson's disease (PD) patients and 7 matched controls. The mRNA levels of 37 genes including neurosteroid biosynthetic enzymes, hormone receptors and the neurosteroid-modulated gamma-amino-butyric acid -A (GABA-A) receptor subunits were analyzed by quantitative PCR (qPCR). In the SN, we found downregulation of 5alpha-reductase type 1 (5alpha-R1), sulfotransferase 2B1 (SULT2B1) and some GABA-A receptor subunits (alpha4, beta1) while in the CN, upregulation of 3alpha-hydroxysteroid dehydrogenase type 3 (3alpha-HSD3) and alpha4 GABA-A receptor subunit (22-fold) was observed. No significant differences were found in the PU. These data imply an involvement of pregnane steroids and changes in GABAergic neurotransmission in the neurodegenerative process and suggest that neurosteroids may deserve further investigation as potential therapeutic agents in PD.

Differential expression of interferon-γ receptor on human glial cells in vivo and in vitro

Although significant effects of interferon-γ (IFN-γ) on glial cells are well documented, information on the expression level and localization of glial IFN-γ receptors (IFN-γ-R) in the human central nervous system (CNS) is sparse. To examine the glial expression of IFN-γ-R in the human CNS, immunohistochemistry and quantitative analyses were performed on Alzheimer disease hippocampus, Parkinson disease substantia nigra, amyotrophic lateral sclerosis spinal cord and corresponding areas from non-neurological cases. Almost all IFN-γ-R-positive (IFN-γ-R +) cells corresponded to GFAP-positive (GFAP +) astrocytes, while none of IFN-γ-R + cells corresponded to IBA1-positive (IBA1 +) microglia or MBP-positive (MBP +) oligodendrocytes in these neurological cases. We observed a similar pattern of glial IFN-γ-R expression in non-neurological cases. Also, we quantitatively analyzed the IFN-γ-R expression by cultured human glial cells using immunocytochemistry and reverse transcription polymerase chain reaction (RT-PCR). In contrast to in vivo results, almost all IFN-γ-R + cells were IBA1 + in microglial cultures, GFAP + in astrocytic cultures and MBP + in oligodendrocytic cultures. Moreover, no significant difference in IFN-γ-R mRNA expression was found for these glial cell types by RT-PCR. These results suggest that the microglial and oligodendrocytic expression levels of IFN-γ-R are much lower than the astrocytic expression levels in the human CNS in vivo, whereas all three types of glial cells constitutively express IFN-γ-R when cultured in vitro.

A comparison of changes in proteasomal subunit expression in the substantia nigra in Parkinson's disease, multiple system atrophy and progressive supranuclear palsy

Dysfunction of the ubiquitin-proteasome system (UPS) occurs in dopaminergic neurones in the SN in PD and it is associated with Lewy body formation. However, it remains unknown whether this is specific to PD or whether it also occurs in multiple system atrophy (MSA) and progressive supranuclear palsy (PSP) where nigral dopaminergic neurones also degenerate. In the present study, we investigated changes in the expression of proteasomal subunits in the SN in PD, MSA and PSP. Immunohistochemistry double staining showed that proteasome 20S-α4 and -α6, and 20S-β3 and -β5i subunits are colocalized with tyrosine hydroxylase (TH)-positive cells in the SN of control, PD, MSA and PSP brain. Semi-quantitative analysis showed a significant loss of 20S-α4 and -α6 subunits TH-positive cells in PD, MSA and PSP compared to control tissue. There was no change in the expression of 20S-β3 and -β5i subunits in any of the disease states. The expression of PA700-Rpt5 subunits was not changed in PSP or PD but was significantly increased in MSA compared to control SN. PA700-Rpn10 subunit was not colocalized with TH within dopamine cells but was co-expressed with glial fibrillary acid protein (GFAP) positive astrocytes in the SN of all groups. PA28-α immunoreactivity was low in TH positive neurones in control tissue and quantification was not possible. Qualitative analysis suggested a decrease in PD and no immunoreactivity was detected in MSA or PSP. The results show that changes in proteasomal structure occur in the SN in PD, MSA and PSP and that these are similar in nature suggesting that dysfunction of UPS is not specific to PD or to Lewy body formation.

Parkinson's disease and growth factors – are they the answer?

The core loss of dopaminergic neurons in the substantia nigra in Parkinson's disease (PD) coupled to the therapeutic benefits of dopaminergic therapies in patients, simplifies the treatment strategy for this disease. In the context of neurotrophic factors, this distils down to the simple question as to whether a factor exists for these cells that can promote their survival in the face of the degenerative disease process. If such a factor exists, and GDNF seems a strong candidate, then one could anticipate that this treatment would be as effective as L-dopa therapy. However it would not be better than this, nor curative, given the extensive pathology in PD. To date a number of clinical trials have been undertaken in which GDNF has been directly delivered to the PD brain. In addition there have been studies in which neurturin (part of the GDNF family) has also been delivered to the CNS using a viral vector delivery system. These trials have produced mixed results. Importantly though, some patients have shown a sustained clinical response to this treatment which correlates with evidence of increased dopaminergic activity in the brain at the site of delivery using F-dopa PET as well as in a single post-mortem study. The challenge therefore is not whether this approach works, because it self-evidently does in some patients, but rather how we can do this more consistently.