title: Venular degeneration leads to vascular dysfunction in a transgenic model of Alzheimer's disease.
abstract: Most patients with Alzheimer's disease exhibit accumulation of amyloid-β peptide on leptomeningeal and cortical arterioles, or cerebral amyloid angiopathy, which is associated with impaired vascular reactivity and accelerated cognitive decline. Despite widespread recognition of the significance of vascular dysfunction in Alzheimer's disease aetiology and progression, much uncertainty still surrounds the mechanism underlying Alzheimer's disease vascular injury. Studies to date have focused on amyloid-β-induced damage to capillaries and plaque-associated arterioles, without examining effects across the entire vascular bed. In the present study, we investigated the structural and functional impairment of the feeding arteriolar versus draining venular vessels in a transgenic murine Alzheimer's disease model, with a particular focus on the mural cell populations that dictate these vessels' contractility. Although amyloid-β deposition was restricted to arterioles, we found that vascular impairment extended to the venules, which showed significant depletion of their mural cell coverage by the mid-stage of Alzheimer's disease pathophysiology. These structural abnormalities were accompanied by an abolishment of the normal vascular network flow response to hypercapnia: this functional impairment was so severe as to result in hypercapnia-induced flow decreases in the arterioles. Further pharmacological depletion of mural cells using SU6668, a platelet-derived growth factor receptor-β antagonist, resulted in profound structural abnormalities of the cortical microvasculature, including vessel coiling and short-range looping, increased tortuosity of the venules but not of the arterioles, increased amyloid-β deposition on the arterioles, and further alterations of the microvascular network cerebral blood flow response to hypercapnia. Together, this work shows hitherto unrecognized structural alterations in penetrating venules, demonstrates their functional significance and sheds light on the complexity of the relationship between vascular network structure and function in Alzheimer's disease.
authors: 1 Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada 2 Sunnybrook Research Institute, Toronto, ON, Canada.
authors: Aaron Y
authors: AY
authors: Lai
authors: 2 Sunnybrook Research Institute, Toronto, ON, Canada.
authors: Adrienne
authors: A
authors: Dorr
authors: 2 Sunnybrook Research Institute, Toronto, ON, Canada.
authors: Lynsie A M
authors: LA
authors: Thomason
authors: 2 Sunnybrook Research Institute, Toronto, ON, Canada.
authors: Margaret M
authors: MM
authors: Koletar
authors: 3 Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada 4 Hospital for Sick Children, Toronto, ON, Canada.
authors: John G
authors: JG
authors: Sled
authors: 2 Sunnybrook Research Institute, Toronto, ON, Canada 3 Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.
authors: Bojana
authors: B
authors: Stefanovic
authors: 1 Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada 2 Sunnybrook Research Institute, Toronto, ON, Canada j.mclaurin@sri.utoronto.ca.
authors: JoAnne
authors: J
authors: McLaurin
mesh_terms: D000544:Alzheimer Disease / Q000473:pathology* / Q000503:physiopathology*; D000818:Animals; D002560:Cerebrovascular Circulation; D006224:Cricetinae; D004195:Disease Models, Animal; D006801:Humans; D051379:Mice; D057507:Mice, 129 Strain; D008822:Mice, Transgenic; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods; D014699:Venules / Q000473:pathology* / Q000503:physiopathology*
keywords: amyloid-β peptide; arterioles; cerebral amyloid angiopathy; mural cells; venules