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Thiol Oxidation by Diamide Leads to Dopaminergic Degeneration and Parkinsonism Phenotype in Mice: A Model for Parkinson's Disease

Ray, Ajit and Kambali, Maltesh and Ravindranath, Vijayalakshmi (2016) Thiol Oxidation by Diamide Leads to Dopaminergic Degeneration and Parkinsonism Phenotype in Mice: A Model for Parkinson's Disease. In: ANTIOXIDANTS & REDOX SIGNALING, 25 (5). pp. 252-267.

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Official URL: http://dx.doi.org/10.1089/ars.2015.6602


Aims: This study investigates the role of thiol homeostasis disruption in Parkinson's disease (PD) pathogenesis using a novel animal model. A single unilateral administration of the thiol oxidant, diamide (1.45 lmol) into substantia nigra (SN) of mice leads to locomotor deficits and degeneration of dopaminergic (DA) neurons in SN pars compacta (SNpc). Results: Diamide-injected mice showed hemiparkinsonian behavior, measured as spontaneous contralateral body rotations, poor grip strength, and impaired locomotion on a rotarod. We observed a significant loss of DA neurons in ipsilateral but not contralateral SNpc and their striatal fibers. This was accompanied by increased Fluoro-Jade C-positive cells and a loss of NeuN-positive neurons, indicative of neurodegeneration. Importantly, diamide injection led to alpha-synuclein aggregation in ipsilateral SNpc, a hallmark of PD pathology not often seen in animal models of PD. On investigating putative mechanism(s) involved, we observed a loss of glutathione, which is essential for maintaining protein thiol homeostasis (PTH). Concomitantly, the redox-sensitive ASK1-p38 mitogen-activated protein kinase (MAPK) death signaling pathway was activated in the ipsilateral but not contralateral ventral midbrain through dissociation of ASK1-Trx1 complex. In Neuro-2a cells, diamide activated ASK1-p38 cascade through Trx1 oxidation, leading to cell death, which was abolished by ASK1 knockdown. Innovation: Since diamide selectively disrupts PTH, DA neurons appear to be vulnerable to such perturbations and even a single insult with a thiol oxidant can result in long-lasting degeneration. Conclusion: Identification of the role of PTH dysregulation in neurodegeneration, especially in early PD, not only facilitates an understanding of novel regulatory features of molecular signaling cascades but also may aid in developing disease-modifying strategies for PD.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the MARY ANN LIEBERT, INC, 140 HUGUENOT STREET, 3RD FL, NEW ROCHELLE, NY 10801 USA
Department/Centre: Division of Biological Sciences > Centre for Neuroscience
Date Deposited: 22 Oct 2016 07:20
Last Modified: 22 Oct 2016 07:20
URI: http://eprints.iisc.ac.in/id/eprint/54807

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