Localization of α-synuclein in teleost central nervous system: immunohistochemical and Western blot evidence by 3D5 monoclonal antibody in the common carp, Cyprinus carpio

Alpha synuclein (α-syn) is a 140 amino acid vertebrate-specific protein, highly expressed in the human nervous system and abnormally accumulated in Parkinson's disease and other neurodegenerative disorders, known as synucleinopathies. The common occurrence of α-syn aggregates suggested a role for α-syn in these disorders, although its biological activity remains poorly understood. Given the high degree of sequence similarity between vertebrate α-syns, we investigated this proteins in the CNS of the common carp Cyprinus carpio, with the aim of comparing its anatomical and cellular distribution with that of mammalian α-syn. The distribution of α-syn was analyzed by semiquantitative Western blot, immunohistochemistry and immunofluorescence by a novel monoclonal antibody (3D5) against a fully conserved epitope between carp and human α-syn. The distribution of 3D5 immunoreactivity was also compared with that of ChAT, TH and 5HT by double immunolabelings. Results show that α-syn-like protein of about 17 kDa is expressed to different levels in several brain regions and in the spinal cord. Immunoreactive materials were localized in neuronal perikarya and varicose fibers but not in the nucleus. Present findings indicate that α-syn-like proteins may be expressed in few subpopulations of catecholaminergic and serotoninergic neurons in the carp brain. However, evidence of cellular colocalization 3D5/TH or 3D5/5HT was rare. Differently, the same proteins appear to be co-expressed with ChAT by cholinergic neurons in several motor and reticular nuclei. These results sustain the functional conservation of the α-syn expression in cholinergic systems and suggest that α-syn modulates similar molecular pathways in phylogenetically distant vertebrates. This article is protected by copyright. All rights reserved

Abnormal salivary total and oligomeric alpha-synuclein in Parkinson's disease

In Parkinson’s disease (PD), alpha-synuclein (a-syn) can be detected in biological fluids including saliva. Although previous studies found reduced a-syn total (a-syntotal) concentration in saliva of PD patients, no studies have previously examined salivary a-syn oligomers (a-synolig) concentrations or assessed the correlation between salivary a-syntotal, a-synolig and clinical features in a large cohort of PD patients. Is well known that a-synolig exerts a crucial neurotoxic effect in PD. We collected salivary samples from 60 PD patients and 40 age- and sex-comparable healthy subjects. PD was diagnosed according to the United Kingdom Brain Bank Criteria. Samples of saliva were analyzed by specific anti-a-syn and anti-oligomeric a-syn ELISA kits. A complete clinical evaluation of each patient was performed using MDS-Unified Parkinson's Disease Rating Scale, Beck Depression Inventory, Montreal Cognitive Assessment and Frontal Assessment Battery. Salivary a-syntotal was lower, whereas a-synolig was higher in PD patients than healthy subjects. The a-synolig/a-syntotal ratio was also higher in patients than in healthy subjects. Salivary a-syntotal concentration negatively correlated with that of a-synolig and correlated with several patients’ clinical features. In PD, decreased salivary concentration of a-syntotal may reflect the reduction of a-syn monomers (a-synmon), as well as the formation of insoluble intracellular inclusions and soluble oligomers. The combined detection of a-syntotal and a-synolig in the saliva might help the early diagnosis of P

Distal Upper Limb Tremor during Walking in Parkinson's Disease

Background: Distal upper limb tremor during walking (TW) is frequently observed in Parkinson's disease (PD) but its clinical features are unknown. Objective: To characterize the occurrence and the clinical features of TW in comparison to the other types of tremors in PD. Methods: Fifty-one PD patients with rest tremor were evaluated off- and on-treatment. Occurrence, body distribution, severity and latency of TW and of other tremor types were assessed. Results: TW was present in 78% of the PD patients examined. TW body distribution and severity were similar to those of rest and re-emergent tremor but different from the postural tremor presented by the same patients. TW latency, observed in 85% of patients, was on average 5.8 s. Dopaminergic treatment significantly improved TW, rest, and re-emergent tremor severity but left TW latency unaffected. Conclusions: TW is a frequent motor sign in PD and is likely a clinical variant of rest tremor

Loss of spinal motor neurons and alteration of alpha-synuclein subcellular localization in MPTP induced parkinsonism in mice

1-methyl, 4-phenyl, 1, 2, 3, 6-tetrahydropiridine (MPTP) is a neurotoxin, widely used to produce experimental models of Parkinson Disease in rodents and primates. Although dopaminergic neurons are the most sensitive to MPTP neurotoxicity, different neuronal subtypes could be affected. In particular, noradrenergic neurons of the Locus Coeruleus may be involved as well as nigral dopaminergic neurons. Moreover, apart from catecholamine-containing nuclei, recent studies indicate that MPTP may produce pathological effects within the spinal cord. This point deserves compelling interest since it suggests, at experimental level, commonalities between Parkinson Disease and Amyotrophic Lateral Sclerosis. For instance, recent reports demonstrate that MPTP activates apoptotic proteins at the level of spinal cord. However, to our knowledge, none of these studies so far analyzed whether motor neuron loss really occurs following MPTP administration. Therefore, in the present study we evaluated the effect of a robust dose of MPTP (20 mg/Kg X3) in the nigro-striatal system and spinal cord. Along with a severe dopaminergic cells loss within the substantia nigra, quantified by stereology and a marked decrease of striatal catecholoamine fibers measured by semi-quantitative densitometry, we found a significant (roughly 30 %) depletion of motor neurons in the lumbar spinal cord of MPTP-treated C57BL/6J mice. At the same level, spared motor neurons often present an altered morphology, being dysmorphic and vacuolated. Furthermore, using four different antibodies (tree monoclonal, one polyclonal), recognizing distinct epitopes in the sequence of alpha-synuclein, we found that alpha-synuclein immunostaining is markedly altered in the spinal cord of MPTP-treated mice. The present data shed new lights on similarities between dopaminergic neurons and spinal motor neurons, while suggesting that MPTP might be a neurotoxin diverse from what originally considered