scholarly journals Diffusion tensor-MRI detects exercise-induced neuroplasticity in the hippocampal microstructure in mice

2020 ◽  
Vol 5 (2) ◽  
pp. 147-159
Author(s):  
Mohammad R. Islam ◽  
Renhao Luo ◽  
Sophia Valaris ◽  
Erin B. Haley ◽  
Hajime Takase ◽  
...  
Keyword(s):  
Animal Studies ◽  
Wheel Running ◽  
Diffusion Tensor ◽  
Hippocampal Volume ◽  
Mri Scans ◽  
Oligodendrocyte Precursor ◽  
Exercise Induced ◽  
Response To Exercise ◽  
The Brain

Background: Despite considerable research on exercise-induced neuroplasticity in the brain, a major ongoing challenge in translating findings from animal studies to humans is that clinical and preclinical settings employ very different techniques. Objective: Here we aim to bridge this divide by using diffusion tensor imaging MRI (DTI), an advanced imaging technique commonly applied in human studies, in a longitudinal exercise study with mice. Methods: Wild-type mice were exercised using voluntary free-wheel running, and MRI scans were at baseline and after four weeks and nine weeks of running. Results: Both hippocampal volume and fractional anisotropy, a surrogate for microstructural directionality, significantly increased with exercise. In addition, exercise levels correlated with effect size. Histological analysis showed more PDGFRα+ oligodendrocyte precursor cells in the corpus callosum of running mice. Conclusions: These results provide compelling in vivo support for the concept that similar adaptive changes occur in the brains of mice and humans in response to exercise.

scholarly journals Exercise training promotes a GDF15-associated reduction in fat mass in older adults with obesity

2019 ◽  
Vol 316 (5) ◽  
pp. E829-E836 ◽  
Author(s):  
Hui Zhang ◽  
Ciarán E. Fealy ◽  
John P. Kirwan
Keyword(s):  
Exercise Training ◽  
Fat Mass ◽  
Animal Studies ◽  
Acute Exercise ◽  
Exercise Intervention ◽  
Resting Energy Expenditure ◽  
Human Obesity ◽  
Total Fat ◽  
Exercise Induced ◽  
Response To Exercise

Obesity is a major risk factor for metabolic disease. Growth differentiation factor 15 (GDF15) has shown promise as a weight loss agent for obesity in animal studies. In healthy lean humans, fasting plasma GDF15 increases after acute exercise. However, the role of GDF15 in human obesity and the response of plasma GDF15 to exercise training in patients with obesity is unknown. Here, 24 sedentary volunteers with obesity [age: 65 ± 1 yr; body mass index (BMI): 35.3 ± 0.9 kg/m2] participated in a supervised 12-wk aerobic exercise intervention: 1 h/day, 5 days/wk at ~85% maximum heart rate with controlled isocaloric diet. As a result, plasma GDF15 was significantly increased (PRE: 644.1 ± 42.6 pg/ml, POST: 704.4 ± 47.2 pg/ml, P < 0.01) after the exercise intervention. Inconsistent with animal models, ΔGDF15 was not correlated with change in weight, BMI, or resting energy expenditure. However, ΔGDF15 was correlated with a reduction in total fat mass ( P < 0.05), abdominal fat mass ( P < 0.05), and android fat mass ( P ≤ 0.05). Participants with a positive GDF15 response to exercise had increased total fat oxidation (PRE: 0.25 ± 0.05 mg·kg−1·min−1, POST: 0.43 ± 0.07 mg·kg−1·min−1, P ≤ 0.05), metabolic flexibility [PRE: −0.01 ± 0.01 delta respiratory quotient (RQ), POST: 0.06 ± 0.01 delta RQ, P < 0.001], and insulin sensitivity (PRE: 0.33 ± 0.01 QUICKI index, POST: 0.34 ± 0.01 QUICKI index, P < 0.01), suggesting a link between GDF15 and fat mass loss as well as exercise-induced metabolic improvement in humans with obesity. We conclude that the exercise-induced increase in plasma GDF15 and the association with reduced fat mass may indicate a role for GDF15 as a therapeutic target for human obesity.

Effects of exercise on endothelium and endothelium/smooth muscle cross talk: role of exercise-induced hemodynamics

2011 ◽  
Vol 111 (1) ◽  
pp. 311-320 ◽  
Author(s):  
S. C. Newcomer ◽  
Dick H. J. Thijssen ◽  
D. J. Green
Keyword(s):  
Physical Activity ◽  
Shear Stress ◽  
Wall Stress ◽  
Beneficial Effects ◽  
Exercise Induced ◽  
Response To Exercise ◽  
And Training

Physical activity, exercise training, and fitness are associated with decreased cardiovascular risk. In the context that a risk factor “gap” exists in the explanation for the beneficial effects of exercise on cardiovascular disease, it has recently been proposed that exercise generates hemodynamic stimuli which exert direct effects on the vasculature that are antiatherogenic. In this review we briefly introduce some of the in vitro and in vivo evidence relating exercise hemodynamic modulation and vascular adaptation. In vitro data clearly demonstrate the importance of shear stress as a potential mechanism underlying vascular adaptations associated with exercise. Supporting this is in vivo human data demonstrating that exercise-mediated shear stress induces localized impacts on arterial function and diameter. Emerging evidence suggests that exercise-related changes in hemodynamic stimuli other than shear stress may also be associated with arterial remodeling. Taken together, in vitro and in vivo data strongly imply that hemodynamic influences combine to orchestrate a response to exercise and training that regulates wall stress and peripheral vascular resistance and contributes to the antiatherogenic impacts of physical activity, fitness, and training.

Exogenous L-lactate promotes astrocyte plasticity but is not sufficient for enhancing striatal synaptogenesis or motor behavior in mice

2020 ◽  
Author(s):  
Adam J. Lundquist ◽  
Tyler J. Gallagher ◽  
Giselle M. Petzinger ◽  
Michael W. Jakowec
Keyword(s):  
Motor Behavior ◽  
Early Gene ◽  
Specific Gene ◽  
Motor Circuits ◽  
Specific Manner ◽  
Primary Astrocytes ◽  
Exercise Induced ◽  
The Brain

AbstractL-lactate is an energetic and signaling molecule that is key to the metabolic and neuroplastic connection between astrocytes and neurons and may be involved in exercise-induced neuroplasticity. This study sought to explore the role of L-lactate in astrocyte reactivity and neuroplasticity. Using in vitro cultures of primary astrocytes, we show L-lactate increased expression of plasticity-related genes, including neurotrophic factors, Bdnf, Gdnf, Cntf and the immediate early gene cFos. L-lactate’s promotion of neurotrophic factor expression may be mediated in part by the lactate receptor HCAR1 since application of the HCAR1 agonist 3,5-DHBA also increased expression of Bdnf in primary astrocytes. In vivo L-lactate administration to healthy mice caused a similar increase in the expression of plasticity-related genes as well as increased astrocyte morphological complexity in a region-specific manner, with increased astrocytic response found in the striatum but not the ectorhinal cortex, regions of the brain where increases in regional cerebral blood flow are increased or unaltered, respectively, with motor behavior. Additionally, L-lactate administration did not cause synaptogenesis or improve motor behavior based on the latency to fall on the accelerating rotarod, suggesting that L-lactate administration can initiate astrocyte-specific gene expression, but the activation of motor circuits is necessary to initiate striatal neuroplasticity. These results suggest that peripheral L-lactate is likely an important molecular component of exercise-induced neuroplasticity by acting in an astrocyte-specific manner to prime the brain for neuroplasticity.

Imaging

2017 ◽  
Author(s):  
Robert Laureno
Keyword(s):  
Resonance Imaging ◽  
Cross Sectional ◽  
Advantages And Disadvantages ◽  
Mri Scans ◽  
Cross Sectional Imaging ◽  
Magnetic Resonance Imaging Mri ◽  
Cellular Pathology ◽  
Brain And Spinal Cord ◽  
The Brain

This chapter on “Imaging” examines the relative advantages and disadvantages of computed tomography (CT) and magnetic resonance imaging (MRI) scans. It compares the modalities to each other and to gross neuropathology. For several decades, neurologists have been able to view cross-sectional images of living patients. Analogous to gross neuropathology, cross-sectional imaging displays the brain as an entire organ but does not demonstrate microscopic tissue or cellular pathology. By allowing practitioners to view sections of brain and spinal cord in vivo, imaging has improved neurologic practice and facilitated clinical research. This chapter deals with imaging topics that are important to the neurologist. The timing of scans, the effects of gravity, and the importance of plane of section are considered. Imaging is compared to gross neuropathology, and MRI is compared to CT.

scholarly journals In vivo detection of connectivity between cortical and white matter lesions in early MS

2016 ◽  
Vol 23 (7) ◽  
pp. 973-981 ◽  
Author(s):  
Jan-Mendelt Tillema ◽  
Stephen D Weigand ◽  
Jay Mandrekar ◽  
Yunhong Shu ◽  
Claudia F Lucchinetti ◽  
...  
Keyword(s):  
White Matter ◽  
Diffusion Tensor ◽  
White Matter Lesions ◽  
Cortical Lesion ◽  
In Vivo Detection ◽  
Relapsing Remitting ◽  
Mri Scans ◽  
Healthy Control ◽  
Magnetic Resonance Imaging Mri

Background: The relationship between cortical lesions (CLs) and white matter lesions (WMLs) in multiple sclerosis (MS) is poorly understood. Pathological studies support a topographical association between CLs and underlying subcortical WMLs and suggest CLs may play a role in both disease initiation and progression. We hypothesized that cortical MS lesions are physically connected to white matter MS lesions via axonal connections. Objective: To assess the presence of CL-WML connectivity utilizing novel magnetic resonance imaging (MRI) methodology. Methods: In all, 28 relapsing-remitting MS patients and 25 controls received 3 T MRI scans, including double inversion recovery (DIR) for CL detection coupled with diffusion tensor imaging (DTI). CL and WML maps were created, and DTI was used to calculate inter-lesional connectivity and volumetric connectivity indices. Results: All patients showed inter-lesional WML connectivity (median 76% of WMLs connected to another WML; interquartile range (IQR), 58%–88%). On average, 52% of detected CLs per patient were connected to at least one WML (IQR, 42%–71%). Volumetric connectivity analysis showed significantly elevated cortical lesion ratios in MS patients (median, 2.3; IQR, 1.6–3.3) compared to null MS and healthy control datasets ( p < 0.001). Conclusion: These findings provide strong evidence of inter-lesional connectivity between CLs and WMLs, supporting our hypothesis of intrinsic CL-WML connectivity.

scholarly journals The Connectivity of the Human Pulvinar: A Diffusion Tensor Imaging Tractography Study

2008 ◽  
Vol 2008 ◽  
pp. 1-5 ◽  
Author(s):  
Sandra E. Leh ◽  
M. Mallar Chakravarty ◽  
Alain Ptito
Keyword(s):  
Diffusion Tensor Imaging ◽  
Visual Processing ◽  
Animal Studies ◽  
Diffusion Tensor ◽  
Human Vision ◽  
Subcortical Structures ◽  
Fiber Tracts ◽  
Visual Spatial ◽  
Visual Areas

Previous studies in nonhuman primates and cats have shown that the pulvinar receives input from various cortical and subcortical areas involved in vision. Although the contribution of the pulvinar to human vision remains to be established, anatomical tracer and electrophysiological animal studies on cortico-pulvinar circuits suggest an important role of this structure in visual spatial attention, visual integration, and higher-order visual processing. Because methodological constraints limit investigations of the human pulvinar's function, its role could, up to now, only be inferred from animal studies. In the present study, we used an innovative imaging technique, Diffusion Tensor Imaging (DTI) tractography, to determine cortical and subcortical connections of the human pulvinar. We were able to reconstruct pulvinar fiber tracts and compare variability across subjects in vivo. Here we demonstrate that the human pulvinar is interconnected with subcortical structures (superior colliculus, thalamus, and caudate nucleus) as well as with cortical regions (primary visual areas (area 17), secondary visual areas (area 18, 19), visual inferotemporal areas (area 20), posterior parietal association areas (area 7), frontal eye fields and prefrontal areas). These results are consistent with the connectivity reported in animal anatomical studies.

scholarly journals Histology and Morphology of the Brain Subarachnoid Trabeculae

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Parisa Saboori ◽  
Ali Sadegh
Keyword(s):  
Animal Studies ◽  
Fibrous Tissue ◽  
Head Movements ◽  
Type I ◽  
Pia Mater ◽  
Transmission Electron ◽  
Bright Field Microscopy ◽  
The Brain

The interface between the brain and the skull consists of three fibrous tissue layers, dura mater, arachnoid, and pia mater, known as the meninges, and strands of collagen tissues connecting the arachnoid to the pia mater, known as trabeculae. The space between the arachnoid and the pia mater is filled with cerebrospinal fluid which stabilizes the shape and position of the brain during head movements or impacts. The histology and architecture of the subarachnoid space trabeculae in the brain are not well established in the literature. The only recognized fact about the trabeculae is that they are made of collagen fibers surrounded by fibroblast cells and they have pillar- and veil-like structures. In this work the histology and the architecture of the brain trabeculae were studied, via a series of in vivo and in vitro experiments using cadaveric and animal tissue. In the cadaveric study fluorescence and bright field microscopy were employed while scanning and transmission electron microscopy were used for the animal studies. The results of this study reveal that the trabeculae are collagen based type I, and their architecture is in the form of tree-shaped rods, pillars, and plates and, in some regions, they have a complex network morphology.

scholarly journals Uncertainty in the DTI Visualization Pipeline

2021 ◽  
pp. 125-148
Author(s):  
Faizan Siddiqui ◽  
Thomas Höllt ◽  
Anna Vilanova
Keyword(s):  
Magnetic Resonance Imaging ◽  
Diffusion Tensor Imaging ◽  
White Matter ◽  
Diffusion Tensor ◽  
Research Directions ◽  
Uncertainty Visualization ◽  
Weighted Magnetic Resonance Imaging ◽  
Fibrous Tissues ◽  
The Brain

AbstractDiffusion-Weighted Magnetic Resonance Imaging (DWI) enables the in-vivo visualization of fibrous tissues such as white matter in the brain. Diffusion-Tensor Imaging (DTI) specifically models the DWI diffusion measurements as a second order-tensor. The processing pipeline to visualize this data, from image acquisition to the final rendering, is rather complex. It involves a considerable amount of measurements, parameters and model assumptions, all of which generate uncertainties in the final result which typically are not shown to the analyst in the visualization. In recent years, there has been a considerable amount of work on the visualization of uncertainty in DWI, and specifically DTI. In this chapter, we primarily focus on DTI given its simplicity and applicability, however, several aspects presented are valid for DWI as a whole. We explore the various sources of uncertainties involved, approaches for modeling those uncertainties, and, finally, we survey different strategies to visually represent them. We also look at several related methods of uncertainty visualization that have been applied outside DTI and discuss how these techniques can be adopted to the DTI domain. We conclude our discussion with an overview of potential research directions.

In vivo evidence against a role for adenosine in the exercise pressor reflex in humans

2005 ◽  
Vol 99 (2) ◽  
pp. 522-527 ◽  
Author(s):  
Niels P. Riksen ◽  
Egidia E. M. van Ginneken ◽  
Petra H. H. van den Broek ◽  
Paul Smits ◽  
Gerard A. Rongen
Keyword(s):  
Cell Damage ◽  
Pressor Response ◽  
Isometric Exercise ◽  
Microdialysis Probe ◽  
Endogenous Adenosine ◽  
Time Control ◽  
Adenosine Concentration ◽  
Exercise Induced ◽  
Response To Exercise

The pressor response to exercise is of great importance in both physiology and pathophysiology. Whether endogenous adenosine is a trigger for this reflex remains controversial. Muscle interstitial adenosine concentration can be determined by microdialysis. However, there are indications that local muscle cell damage by the microdialysis probe confounds these measurements in exercising muscle. Therefore, we used the nucleoside uptake inhibitor dipyridamole as pharmacological tool to bypass this confounding. We used microdialysis probes to measure endogenous adenosine in forearm skeletal muscle of healthy volunteers during two cycles of 15 min of intermittent isometric handgripping. During the second contraction, dipyridamole (12 μg·min−1·dl forearm−1) was administered into the brachial artery. Dipyridamole potentiated the exercise-induced increase in dialysate adenosine from 0.30 ± 0.08 to 0.48 ± 0.10 μmol/l ( n = 9, P < 0.05), but it did not potentiate the exercise-induced increase in blood pressure. A time-control study without dipyridamole revealed no difference in exercise-induced increase in adenosine between both contractions ( n = 8). To exclude the possibility that the dipyridamole-induced increase in dialysate adenosine originates from extravasation of increased circulating adenosine, we simultaneously measured adenosine with microdialysis probes in forearm muscle and antecubital vein. In a separate group of nine volunteers, simultaneous intrabrachial infusion of 100 μg·min−1·dl−1 dipyridamole and 5 μg·min−1·dl−1 adenosine increased dialysate adenosine from the intravenous but not the interstitial probe, indicating preserved endothelial barrier function for adenosine. We conclude that dipyridamole significantly inhibits uptake of interstitial adenosine without affecting the pressor response to exercise, suggesting that interstitial adenosine is not involved in the pressor response to rhythmic isometric exercise.

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