Lack of modulation of brain resting state networks by fasting and ghrelin in humans
Sunday, Oct 14, 2012, 4:00 PM - 5:00 PM
*J. A. STARKE
, C. G. PRECHTL
, S. SCHOLTZ
, N. CHHINA
, A. MIRAS
, G. DURIGHEL
, R. LEECH
, D. J. SHARP
, C. F. BECKMANN
, G. S. FROST
, S. R. BLOOM
, J. D. BELL
, A. P. GOLDSTONE
Metabolic and Mol. Imaging Group, MRC Clin. Sci. Ctr.,
Robert Steiner MRI Unit,
Computational, Cognitive and Clin. Neuroimaging Lab.,
Div. of Diabetes, Endocrinol. and Metabolism, Imperial Col. London, London, United Kingdom
Understanding the brain networks underlying appetite regulation, eating behaviour and food reward is of major importance in understanding the pathophysiology of obesity and the development of novel therapies. Fasting and the stomach-derived orexigenic hormone ghrelin increase appetite, food hedonics and activation of brain reward systems to visual food cues during functional MRI tasks. Brain activity in the resting state (i.e. in the absence of a task) is also functionally relevant. A number of resting state networks (RSN) have been identified e.g. the default mode network (DMN, including precuneus, posterior cingulate and prefrontal cortex), salience network (SALN, including insula, anterior cingulate and orbitofrontal (OFC) cortex) and auditory network (AUDN, including Heschl’s and posterior superior temporal gyri). Activity within these networks may be altered in patients with disease, but also within subjects depending on physiological state. We hypothesised that fasting and ghrelin would influence activity in RSN, increasing network integrity in the SALN while reducing integrity in the DMN.
22 healthy, non-obese subjects (17 male, mean ± SD age 25.9 ± 8yrs, BMI 23.9 ± 2.7 kg/m
) attended after an overnight fast. Subjects remained fasted at the first visit [Fasted-Initial], and then in a randomised cross-over design at 3 subsequent visits, either remained fasted [Fasted-Saline], or ate a 730 kCal breakfast at t=0min, followed by a subcutaneous injection of saline [Fed-Saline] or 3.6 nmol/kg octanylated ghrelin [Fed-Ghrelin] at +55min. Subjects had a 10min resting state fMRI scan at +85min (3T, 186 volumes, TR 3sec). Independent component analysis was used to identify the DMN, SALN and AUDN from the Fasted-Initial visit resting fMRI scan. Dual regression and region of interest (ROI) analyses were used to compare network integrity for each RSN between Fasted-Saline and Fed-Saline visits, and Fed-Ghrelin and Fed-Saline visits using FSL. ROIs were the subcomponents of each RSN as listed above.
There was no significant effect of fasting or ghrelin on resting DMN, SALN or AUDN integrity in either whole brain or within network (randomise t>2.5 or TFCE, corrected P<0.05) or ROI (paired t-test, P=0.3-1.0) analyses.
These findings suggest that current feeding state is unlikely to be a confounding factor within- or between-subjects when performing RSN fMRI studies. However examination of the potential effects of nutritional status on RSN after larger meals, at different time points after eating and in obese subjects will be needed to confirm this conclusion in other experimental circumstances.
UK Medical Research Council
Imperial College Healthcare Charity
European Union FP7
NIHR Biomedical Research Centre
[Authors]. [Abstract Title]. Program No. XXX.XX. 2012 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2012. Online.
2012 Copyright by the Society for Neuroscience all rights reserved. Permission to republish any abstract or part of any abstract in any form must be obtained in writing by SfN office prior to publication.
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