Neuronal expression of familial Parkinson's disease A53T α-synuclein causes early motor impairment, reduced anxiety and potential sleep disturbances in mice.
BACKGROUND
Mutations in the human α-synuclein gene lead to early-onset Parkinson's disease (PD); however, phenotypes of α-synuclein mutant mice vary depending upon the promoter driving transgene expression.


OBJECTIVE
The goal of this study was to characterize behavior and neurochemical alterations in mice expressing mutant (A53T) human α-synuclein, controlled by a neuron-specific Thy-1 promoter. Our data provide important additional phenotypic and biochemical characterization of a previously generated model of PD.


METHODS
A53T (SNCA) and wild type (WT) littermate mice were evaluated for motor function (rotarod and stride length) and anxiety (elevated plus maze and open field) every 2 weeks. At 24 weeks mice were evaluated in a Comprehensive Lab Animal Monitoring System (CLAMS). A separate cohort of mice were euthanized at 12, 24 and 36 weeks for immunoblot analysis of α-synuclein, dopamine transporter (DAT) and tyrosine hydroxylase (TH) in the striatum, and hypothalamic serotonin and metabolites were measured.


RESULTS
SNCA mice display significant motor deficits at 14-18 weeks of age compared to WT mice, which progress over time. CLAMS analysis revealed an increase in activity during the dark phase and a reduction in overall estimated sleep time for SNCA mice compared to WT consistent with clinical reports of sleep abnormalities in PD. A transient change in the levels of DAT appeared at 12 weeks in the striatum and serotonin levels were also altered in the hypothalamus at this time point.


CONCLUSIONS
This PD model displays consistent and clinically relevant motor and sleep phenotypes. Anxiety phenotypes are consistent with other α-synuclein based PD models yet incongruous with typical clinical symptoms. Early increases in serotonin levels potentially explain reductions in anxiety behaviors and sleep.
Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA. srothman02@gmail.com
Sarah M
SM
Rothman
Kathleen J
KJ
Griffioen
Neil
N
Vranis
Bruce
B
Ladenheim
Wei-na
WN
Cong
Jean-Lud
JL
Cadet
Jamie
J
Haran
Bronwen
B
Martin
Mark P
MP
Mattson
D000367:Age Factors; D000818:Animals; D001007:Anxiety / Q000175:diagnosis / Q000209:etiology*; D001921:Brain / Q000378:metabolism / Q000473:pathology*; D004195:Disease Models, Animal; D050483:Dopamine Plasma Membrane Transport Proteins / Q000378:metabolism; D005106:Exploratory Behavior / Q000502:physiology; D005786:Gene Expression Regulation; D006801:Humans; D007381:Intermediate Filament Proteins / Q000235:genetics*; D018782:Maze Learning / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation / Q000235:genetics*; D010300:Parkinson Disease / Q000150:complications / Q000235:genetics / Q000473:pathology; D011597:Psychomotor Performance / Q000502:physiology; D012893:Sleep Wake Disorders / Q000209:etiology*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D050483:Dopamine Plasma Membrane Transport Proteins; D007381:Intermediate Filament Proteins; C430456:desmuslin; D014446:Tyrosine 3-Monooxygenase