Progression of Parkinson's Disease Pathology Is Reproduced by Intragastric Administration of Rotenone in Mice

et al. (2010) Progression of Parkinson's Disease Pathology Is Reproduced by Intragastric Administration of Rotenone in Mice. PLoS ONE 5(1): e8762. doi:10.1371/journal.pone.0008762 Progression of Parkinson's Disease Pathology Is Reproduced by Intragastric Administration of Rotenone in Mice Francisco Pan-Montojo 0 Oleg Anichtchik 0 Yanina Dening 0 Lilla Knels 0 Stefan Pursche 0 Roland Jung 0 Sandra Jackson 0 Gabriele Gille 0 Maria Grazia Spillantini 0 Heinz Reichmann 0 Richard H. W. 0 Funk 0 Christoph Kleinschnitz, Julius-Maximilians-Universitat W urzburg, Germany 0 1 Institute of Anatomy, Medical Faculty Carl Gustav Carus, Dresden University of Technology , Dresden, Germany , 2 Department of Neurology, Medical Faculty Carl Gustav Carus, Dresden University of Technology , Dresden, Germany, 3 Center for Brain Repair , University of Cambridge, Cambridge, United Kingdom, 4 Department of Internal Medicine I, Medical Faculty Carl Gustav Carus, Dresden University of Technology , Dresden, Germany, 5 Experimental Center , Medical Faculty Carl Gustav Carus, Dresden University of Technology , Dresden, Germany , 6 International Max-Planck Research School, Max-Planck Institute for Cell Biology and Genetics , Dresden , Germany In patients with Parkinson's disease (PD), the associated pathology follows a characteristic pattern involving inter alia the enteric nervous system (ENS), the dorsal motor nucleus of the vagus (DMV), the intermediolateral nucleus of the spinal cord and the substantia nigra, providing the basis for the neuropathological staging of the disease. Here we report that intragastrically administered rotenone, a commonly used pesticide that inhibits Complex I of the mitochondrial respiratory chain, is able to reproduce PD pathological staging as found in patients. Our results show that low doses of chronically and intragastrically administered rotenone induce alpha-synuclein accumulation in all the above-mentioned nervous system structures of wild-type mice. Moreover, we also observed inflammation and alpha-synuclein phosphorylation in the ENS and DMV. HPLC analysis showed no rotenone levels in the systemic blood or the central nervous system (detection limit [rotenone],20 nM) and mitochondrial Complex I measurements showed no systemic Complex I inhibition after 1.5 months of treatment. These alterations are sequential, appearing only in synaptically connected nervous structures, treatment timedependent and accompanied by inflammatory signs and motor dysfunctions. These results strongly suggest that the local effect of pesticides on the ENS might be sufficient to induce PD-like progression and to reproduce the neuroanatomical and neurochemical features of PD staging. It provides new insight into how environmental factors could trigger PD and suggests a transsynaptic mechanism by which PD might spread throughout the central nervous system. - Funding: F.P.-M. is the recipient of a grant from the Pedro Barrie de la Maza Foundation. O.A. and M.G.S. are recipients of a grant from the UK Parkinsons Disease Society. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: Francisco Pan-Montojo has a patent application pending for this animal model (Application number PCT/EP 2009/005688). This does not alter the authors adherence to all the PLoS ONE policies on sharing data and materials, as detailed online in the guide for authors (http://www.plosone.org/static/ policies.action#sharing). Parkinsons Disease (PD) is a highly prevalent disease affecting 0.3% of the general population and 13% of the population over the age of 65 [1]. PD is slowly progressive, and is characterized by dysfunction of the somatomotor system (i.e., rigidity, bradykinesia, postural instability, gait dysfunction and tremor), which usually dominates the clinical picture of sporadic PD [2]. The main symptoms are caused by the progressive degeneration of the nigrostriatal dopaminergic pathway [3,4] These complaints, however, are often preceded or accompanied by other symptoms that also emerge during the disease course [5,6,7]. Hyposmia and gastrointestinal alterations are among the non-motor signs that develop early, often preceding motor symptoms by years [8,9,10,11], and are normally accompanied by autonomic dysfunction [12,13] as well as the experience of pain [14,15]. A pathological hallmark of PD is the accumulation of filamentous, cytoplasmic inclusions consisting mainly of alphasynuclein aggregations in the form of Lewy bodies (LB) or Lewy neurites (LN) [16,17]. They are found in certain areas of the central nervous system (CNS), e.g. the dorsal motor nucleus of the vagus (DMV), the intermediolateral nucleus in the spinal cord (IML), the locus coeruleus (LC) and the olfactory bulb (OB), and of the peripheral nervous system (PNS) e.g., celiac ganglia and ENS, of PD patients [18,19,20,21]. These pathological findings are usually associated with an inflammatory response [22] and phosphorylation of the alpha-synuclein (Ser129) which accumulates as a component of LB in the brains of patients with alphasynucleinopathies [23]. Although genetic mutations contribute to the development of rare familial forms of PD (e.g. mutations in alpha-synuclein, Parkin, LRRK2, PINK1 genes) [24,25,26] most of the cases are sporadic and due to unclear aetiologies. It has been postulated that mitochondrial dysfunction [27], oxidative stress [28], inflammatory response [29] and protein mishandling may play an important role in the pathogenesis of sporadic PD [30]. On the other hand, multiple epidemiological studies suggest an association between pesticides and the incidence of PD [31]. Many studies have used different pesticides and routes of administration in order to reproduce pathological and clinical findings of PD in animals [32]. These models show different combinations of the clinical and pathological features of PD, such as the selective loss of TH-positive neurons, the presence of LB in the SN, impaired striatal dopaminergic innervation or motor dysfunction. Nevertheless, they fail to reproduce the complete spectrum of pathological disease progression and provide little information on the risk of environmental exposure because these methods bypass the physical and metabolic defences of the organism. Moreover, systemic administration of rotenone in C57BL/6J mice has failed to reproduce any of the pathological features of PD [33]. Braak and colleagues have suggested that the pathological process starts in the ENS and OB progressing into the CNS through anatomically connected structures [21]. Interestingly, it has been shown that alpha-synuclein oligomeres can be endocytosed by neurons and induce alpha-synuclein aggregation in primary neuronal cultures [34,35]. Moreover, Desplats and colleagues have shown inclusion formation and neuronal cell death through neuron-to-neuron transport of alpha-synuclein both in vivo and in (...truncated)