Arterial Pulsations cannot Drive Intramural Periarterial Drainage: Significance for A β Drainage

• Published in: Frontiers in neuroscience Vol. 11; p. 475
• Main Authors: Diem, Alexandra K, MacGregor Sharp, Matthew, Gatherer, Maureen, Bressloff, Neil W, Carare, Roxana O, Richardson, Giles
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Research Foundation 24-08-2017; Frontiers Media S.A
• Subjects: Alzheimer's disease; Amyloid; Arteries; Arteriosclerosis; Basement membranes; Blood flow; Brain; Capillaries; cerebral blood flow; cerebral lymphatics; Cognitive ability; Dementia; Dementia disorders; Hypotheses; intramural periarterial drainage; Lymphatic system; Mathematical models; Metabolites; Neurodegenerative diseases; Neuroscience; Numerical analysis; perivascular drainage; Permeability; Prophylaxis; Proteins; Veins & arteries; United Kingdom > UK; cerebral lymphatics; cerebral blood flow; intramural periarterial drainage; perivascular drainage; Alzheimer's disease
• ISSN: 1662-4548; 1662-453X; 1662-453X
• DOI: 10.3389/fnins.2017.00475

Alzheimer's Disease (AD) is the most common form of dementia and to date there is no cure or efficient prophylaxis. The cognitive decline correlates with the accumulation of amyloid-β (
β) in the walls of capillaries and arteries. Our group has demonstrated that interstitial fluid and
β are eliminated from the brain along the basement membranes of capillaries and arteries, the intramural periarterial drainage (IPAD) pathway. With advancing age and arteriosclerosis, the stiffness of arterial walls, this pathway fails in its function and
β accumulates in the walls of arteries. In this study we tested the hypothesis that arterial pulsations drive IPAD and that a valve mechanism ensures the net drainage in a direction opposite to that of the blood flow. This hypothesis was tested using a mathematical model of the drainage mechanism. We demonstrate firstly that arterial pulsations are not strong enough to produce drainage velocities comparable to experimental observations. Secondly, we demonstrate that a valve mechanism such as directional permeability of the IPAD pathway is necessary to achieve a net reverse flow. The mathematical simulation results are confirmed by assessing the pattern of IPAD in mice using pulse modulators, showing no significant alteration of IPAD. Our results indicate that forces other than the cardiac pulsations are responsible for efficient IPAD.