AbstractsBiology & Animal Science

«In vivo» MRI studies of structural changes in the mouse brain following forced treadmill training

by Brocke Addison

Institution: McGill University
Department: Integrated Program in Neuroscience
Degree: MS
Year: 2015
Keywords: Biology - Neuroscience
Record ID: 2062307
Full text PDF: http://digitool.library.mcgill.ca/thesisfile130605.pdf


IntroductionEnvironmental enrichment and exercise are known to promote brain plasticity. The cellularunderpinnings associated with plasticity related changes to brain structure remain unknown.Anatomical changes of volume and biochemistry occurring in the brain following forcedtreadmill training are well documented in both animal and human literature, but little is knownabout the underlying physiology of how one is connected to the other. The objective of this studywas therefore to perform longitudinal in vivo scans following exercise and to investigate theseunderlying cellular mechanisms.Methods3-month-old CD1 male littermate mice were randomly assigned to two groups. One group (n=15) was exposed to 6 weeks of forced treadmill (FT) at escalating speeds, increasing 1cm/secper week beginning at 24cm/sec. A control group (n = 12) received no treadmill exposure (NX)for the same 6-week interval.Mice were spatially normalized to an anatomical template (PERMITSTM, Biospective Inc.),providing extracted mean values of volume in 7 different cortical and subcortical regions. Allscans were obtained from a 7T Bruker Pharmascan system. Baseline scans were obtainedfollowing a weeklong training at low speed (15cm/sec) for all mice. A second scan was obtainedfrom each mouse following the 6-week interval of either forced treadmill or no exercise. Uponcompletion of the final scan, all animals were sacrificed for histological examination.ResultsAnalysis of volume measurements taken from baseline and post-exercise scans revealed that 6weeks of forced treadmill led to a significantly larger increase in hippocampal volume in FT mice(13.74%) compared to the increase in NX controls (4.13%) (t(24) = 8.36, p < 0.0001). Analysisof the amygdala showed an increase in volume in the FT group (6.21%) compared to a decreasein amygdala volume in the NX controls (-1.39%) (t(24) = 3.8, p < 0.001). Explored groupdifferences in cortical thickness and volume for 5 other regions revealed no significantdistinction.ConclusionsWe observed a significant increase in both hippocampal and amygdala volume of mice followingforced treadmill compared to controls. The cellular physiology that underlies these increases isbeing investigated and will reveal a better understanding of how these regions change afterexercise training and how the brain changes in response to activity. Présentation enrichissement de l'environnement et l'exercice sont connus pour favoriser la plasticité du cerveau. Les fondements cellulaires associés à la plasticité des changements liés à la structure du cerveau restent inconnus. Les changements anatomiques de volume et de la biochimie qui se produisent dans le cerveau suit entraînement sur tapis roulant sont bien documentés dans la littérature à la fois animale et humaine forcés, mais on sait peu sur la physiologie sous-jacente de la façon dont une est reliée à l'autre. L'objectif de cette étude était donc d'effectuer longitudinale dans les analyses in vivo après l'exercice et d'étudier ces mécanismes cellulaires sous-jacents. Méthodes 3 -…