Amyloid- <i>β</i> disrupts unitary calcium entry through endothelial NMDA receptors in mouse cerebral arteries
Emily C Peters, Michael T Gee, Lukas N Pawlowski, Allison M Kath, Felipe D Polk, Christopher J Vance, Juliana L Sacoman, Paulo W Pires
Abstract
Transient increases in intracellular Ca 2+ activate endothelium-dependent vasodilatory pathways. This process is impaired in cerebral amyloid angiopathy, where amyloid- β (1-40) accumulates around blood vessels. In neurons, amyloid- β impairs the Ca 2+ -permeable N-methyl-D-aspartate receptor (NMDAR), a mediator of endothelium-dependent dilation in arteries. We hypothesized that amyloid- β (1-40) reduces NMDAR-elicited Ca 2+ signals in mouse cerebral artery endothelial cells, blunting dilation. Cerebral arteries isolated from 4-5 months-old, male and female cdh5:Gcamp8 mice were used for imaging of unitary Ca 2+ influx through NMDAR ( NMDAR sparklets) and intracellular Ca 2+ transients. The NMDAR agonist NMDA (10 µmol/L) increased frequency of NMDAR sparklets and intracellular Ca 2+ transients in endothelial cells; these effects were prevented by NMDAR antagonists D-AP5 and MK-801. Next, we tested if amyloid- β (1-40) impairs NMDAR-elicited Ca 2+ transients. Cerebral arteries incubated with amyloid- β (1-40) (5 µmol/L) exhibited reduced NMDAR sparklets and intracellular Ca 2+ transients. Lastly, we observed that NMDA-induced dilation of pial arteries is reduced by acute intraluminal amyloid- β (1-40) , as well as in a mouse model of Alzheimer’s disease, the 5x-FAD, linked to downregulation of Grin1 mRNA compared to wild-type littermates. These data suggest that endothelial NMDAR mediate dilation via Ca 2+ -dependent pathways, a process disrupted by amyloid- β (1-40) and impaired in 5x-FAD mice.