title: Assessing recovery from neurodegeneration in spinocerebellar ataxia 1: Comparison of in vivo magnetic resonance spectroscopy with motor testing, gene expression and histology.
abstract: Suppression of transgene expression in a conditional transgenic mouse model of spinocerebellar ataxia 1 (SCA1) reverses the Purkinje cell pathology and motor dysfunction that are hallmarks of SCA1. We previously showed that cerebellar neurochemical levels measured by magnetic resonance spectroscopy (MRS) correlate with progression of pathology and clinical status of patients and that abnormal neurochemical levels normalize upon suppression of transgene expression, indicating their potential as robust surrogate markers of treatment effects. Here we investigated the relative sensitivities of MRS, histology, transgene expression and motor behavioral testing to disease reversal in conditional SCA1 mice. Transgene expression was suppressed by doxycycline administration and treated and untreated mice were assessed by MRS at 9.4tesla before and after treatment and with an accelerating Rotarod, histology and quantitative polymerase chain reaction (qPCR) for ataxin-1 transgene expression following doxycycline treatment. The MRS-measured N-acetylaspartate-to-myo-inositol ratio (NAA/Ins) correlated significantly with the molecular layer (ML) thickness and transgene expression. NAA/Ins, ML thickness and transgene expression were highly significantly different between the treated vs. untreated groups (p<0.0001), while the Rotarod assessment showed a trend for treatment effect. MRS, qPCR and histology had high sensitivity/specificity to distinguish treated from untreated mice, all with areas under the curve (AUC)=0.97-0.98 in receiver operating characteristic (ROC) analyses, while Rotarod had significantly lower sensitivity and specificity (AUC=0.72). Therefore, MRS accurately reflects the extent of recovery from neurodegeneration with sensitivity similar to invasive measures, further validating its potential as a surrogate marker in pre-clinical and clinical treatment trials.
authors.affiliation: Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, 2021 6th St. SE, Minneapolis, MN 55455, USA. Electronic address: gulin@cmrr.umn.edu.
authors.forename: Gülin
authors.initials: G
authors.lastname: Öz
authors.affiliation: Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, 2021 6th St. SE, Minneapolis, MN 55455, USA.
authors.forename: Emily
authors.initials: E
authors.lastname: Kittelson
authors.affiliation: Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, 2021 6th St. SE, Minneapolis, MN 55455, USA.
authors.forename: Döne
authors.initials: D
authors.lastname: Demirgöz
authors.affiliation: Department of Laboratory Medicine and Pathology, University of Minnesota Medical School, 420 Delaware Street SE, Minneapolis, MN 55455, USA.
authors.forename: Orion
authors.initials: O
authors.lastname: Rainwater
authors.affiliation: Division of Biostatistics, School of Public Health, University of Minnesota, 420 Delaware Street SE, Minneapolis, MN 55455, USA.
authors.forename: Lynn E
authors.initials: LE
authors.lastname: Eberly
authors.affiliation: Department of Laboratory Medicine and Pathology, University of Minnesota Medical School, 420 Delaware Street SE, Minneapolis, MN 55455, USA.
authors.forename: Harry T
authors.initials: HT
authors.lastname: Orr
authors.affiliation: Department of Laboratory Medicine and Pathology, University of Minnesota Medical School, 420 Delaware Street SE, Minneapolis, MN 55455, USA.
authors.forename: H Brent
authors.initials: HB
authors.lastname: Clark
mesh_terms: D000818:Animals; D019540:Area Under Curve; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D000067696:Ataxin-1 / Q000235:genetics / Q000378:metabolism; D002531:Cerebellum / Q000378:metabolism* / Q000473:pathology*; D004318:Doxycycline; D015870:Gene Expression; D006801:Humans; D007294:Inositol / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D008822:Mice, Transgenic; D009043:Motor Activity / Q000502:physiology; D016133:Polymerase Chain Reaction; D012372:ROC Curve; D020127:Recovery of Function / Q000502:physiology*; D045442:Rotarod Performance Test / Q000379:methods; D012680:Sensitivity and Specificity; D020754:Spinocerebellar Ataxias / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology
chemical_list: C000593749:ATXN1 protein, human; D000067696:Ataxin-1; D001224:Aspartic Acid; D007294:Inositol; C000179:N-acetylaspartate; D004318:Doxycycline
keywords: Histology; Magnetic resonance spectroscopy; Outcome measures; Receiver operating characteristic analysis; Rotarod; Spinocerebellar ataxia; Transgenic