title: A phenotypic model recapitulating the neuropathology of Parkinson's disease.
abstract: This study was undertaken to develop a phenotypic model recapitulating the neuropathology of Parkinson's disease (PD). Such a model would show loss of dopamine in the basal ganglia, appearance of Lewy bodies, and the early stages of motor dysfunction. The model was developed by subcutaneously injecting biodegradable microspheres of rotenone, a complex I inhibitor in 8-9 month old, ovariectomized Long-Evans rats. Animals were observed for changes in body weight and motor activity. At the end of 11-12 weeks animals were euthanized and the brains examined for histopathological changes. Rotenone treated animals gain weight and appear normal and healthy as compared to controls but showed modest hypokinesia around 5-6 weeks posttreatment. Animals showed loss of dopaminergic (DA) neurons and the appearance of putative Lewy bodies in the substantia nigra. Neuroinflammation and oxidative stress were evidenced by the appearance of activated microglia, iron precipitates, and 8-oxo-2'-deoxyguanosine a major product of DNA oxidation. The dorsal striatum, the projection site of midbrain DA neurons, showed a significant reduction in tyrosine hydroxylase immunostaining, together with an increase in reactive astrocytes, an early sign of DA nerve terminal damage. Levels of vesicular monoamine transporter 2 (VMAT2) were significantly reduced in the dorsal striatum; however, there was an unexpected increase in dopamine transporter (DAT) levels. Old, ovariectomized females treated with rotenone microspheres present with normal weight gain and good health but a modest hypokinesia. Accompanying this behavioral phenotype are a constellation of neuropathologies characteristic of PD that include loss of DA neurons, microglia activation, oxidative damage to nuclear DNA, iron deposition, and appearance of putative Lewy bodies. This phenotypic model recapitulating the neuropathology of Parkinson's disease could provide insight into early mechanisms of pathogenesis and could aid in the identification of biomarkers to identify patients in early stage, PD.
authors.affiliation: Center for Translational NeuroImaging, Northeastern University Boston, Massachusetts.
authors.forename: Craig F
authors.initials: CF
authors.lastname: Ferris
authors.affiliation: Division of Biochemistry, Department of Molecular and Experimental Medicine, The Scripps Research Institute La Jolla, California.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Marella
authors.affiliation: State University of New York Upstate Medical University Syracuse, New York.
authors.forename: Brian
authors.initials: B
authors.lastname: Smerkers
authors.affiliation: Center for Translational NeuroImaging, Northeastern University Boston, Massachusetts.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Barchet
authors.affiliation: InviCRO, LLC Boston, Massachusetts.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Gershman
authors.affiliation: Division of Biochemistry, Department of Molecular and Experimental Medicine, The Scripps Research Institute La Jolla, California.
authors.forename: Akemi
authors.initials: A
authors.lastname: Matsuno-Yagi
authors.affiliation: Division of Biochemistry, Department of Molecular and Experimental Medicine, The Scripps Research Institute La Jolla, California.
authors.forename: Takao
authors.initials: T
authors.lastname: Yagi
keywords: DNA oxidation; Lewy bodies; dopamine transporter; oxidative stress; rotenone; tyrosine hydroxylase; vesicular monoamine transporter