A NO way to BOLD? Dietary nitrate alters the hemodynamic response to visual stimulation

TY - JOUR

T1 - A NO way to BOLD?

T2 - Dietary nitrate alters the hemodynamic response to visual stimulation

AU - Aamand, Rasmus

AU - Dalsgaard, Thomas

AU - Ho, Yi-Ching Lynn

AU - Møller, Arne

AU - Roepstorff, Andreas

AU - Lund, Torben E

N1 - © 2013 Elsevier Inc. All rights reserved.

PY - 2013/12

Y1 - 2013/12

N2 - Neurovascular coupling links neuronal activity to vasodilation. Nitric oxide (NO) is a potent vasodilator, and in neurovascular coupling NO production from NO synthases plays an important role. However, another pathway for NO production also exists, namely the nitrate-nitrite-NO pathway. On this basis, we hypothesized that dietary nitrate (NO3-) could influence the brain's hemodynamic response to neuronal stimulation. In the present study, 20 healthy male participants were given either sodium nitrate (NaNO3) or sodium chloride (NaCl) (saline placebo) in a crossover study and were shown visual stimuli based on the retinotopic characteristics of the visual cortex. Our primary measure of the hemodynamic response was the blood oxygenation level dependent (BOLD) response measured with high-resolution functional magnetic resonance imaging (0.64×0.64×1.8 mm) in the visual cortex. From this response, we made a direct estimate of key parameters characterizing the shape of the BOLD response (i.e. lag and amplitude). During elevated nitrate intake, corresponding to the nitrate content of a large plate of salad, both the hemodynamic lag and the BOLD amplitude decreased significantly (7.0±2% and 7.9±4%, respectively), and the variation across activated voxels of both measures decreased (12.3±4% and 15.3±7%, respectively). The baseline cerebral blood flow was not affected by nitrate. Our experiments demonstrate, for the first time, that dietary nitrate may modulate the local cerebral hemodynamic response to stimuli. A faster and smaller BOLD response, with less variation across local cortex, is consistent with an enhanced hemodynamic coupling during elevated nitrate intake. These findings suggest that dietary patterns, via the nitrate-nitrite-NO pathway, may be a potential way to affect key properties of neurovascular coupling. This could have major clinical implications, which remain to be explored.

AB - Neurovascular coupling links neuronal activity to vasodilation. Nitric oxide (NO) is a potent vasodilator, and in neurovascular coupling NO production from NO synthases plays an important role. However, another pathway for NO production also exists, namely the nitrate-nitrite-NO pathway. On this basis, we hypothesized that dietary nitrate (NO3-) could influence the brain's hemodynamic response to neuronal stimulation. In the present study, 20 healthy male participants were given either sodium nitrate (NaNO3) or sodium chloride (NaCl) (saline placebo) in a crossover study and were shown visual stimuli based on the retinotopic characteristics of the visual cortex. Our primary measure of the hemodynamic response was the blood oxygenation level dependent (BOLD) response measured with high-resolution functional magnetic resonance imaging (0.64×0.64×1.8 mm) in the visual cortex. From this response, we made a direct estimate of key parameters characterizing the shape of the BOLD response (i.e. lag and amplitude). During elevated nitrate intake, corresponding to the nitrate content of a large plate of salad, both the hemodynamic lag and the BOLD amplitude decreased significantly (7.0±2% and 7.9±4%, respectively), and the variation across activated voxels of both measures decreased (12.3±4% and 15.3±7%, respectively). The baseline cerebral blood flow was not affected by nitrate. Our experiments demonstrate, for the first time, that dietary nitrate may modulate the local cerebral hemodynamic response to stimuli. A faster and smaller BOLD response, with less variation across local cortex, is consistent with an enhanced hemodynamic coupling during elevated nitrate intake. These findings suggest that dietary patterns, via the nitrate-nitrite-NO pathway, may be a potential way to affect key properties of neurovascular coupling. This could have major clinical implications, which remain to be explored.

KW - Administration, Oral

KW - Adult

KW - Blood Flow Velocity

KW - Brain Mapping

KW - Cerebrovascular Circulation

KW - Cross-Over Studies

KW - Double-Blind Method

KW - Humans

KW - Magnetic Resonance Imaging

KW - Male

KW - Nitrates

KW - Nitric Oxide

KW - Nitrites

KW - Photic Stimulation

KW - Placebo Effect

KW - Reproducibility of Results

KW - Sensitivity and Specificity

KW - Visual Perception

U2 - 10.1016/j.neuroimage.2013.06.069

DO - 10.1016/j.neuroimage.2013.06.069

M3 - Journal article

C2 - 23827330

SN - 1053-8119

VL - 83

SP - 397

EP - 407

JO - NeuroImage

JF - NeuroImage

ER -