Increased susceptibility to amyloid-β toxicity in rat brain microvascular endothelial cells under hyperglycemic conditions.
We hypothesized that hyperglycemia-induced mitochondrial dysfunction and oxidative stress are closely associated with amyloid-β peptide (Aβ) toxicity in endothelial cells. Brain microvascular endothelial cells from rat (RBMEC) and mice (MBMEC) were isolated from adult Sprague-Dawley rats and homozygous db/db (Leprdb/Leprdb) and heterozygous (Dock7m/Leprdb) mice, and cultured under normo- and hyperglycemic conditions for 7 d followed by 24 h exposure to Aβ1-40. Some experiments were also performed with two mitochondrial superoxide (O2•-) scavengers, MitoTempo and Peg-SOD. Cell viability was measured by the Alamar blue assay and mitochondrial membrane potential (ΔΨm) by confocal microscopy. Mitochondrial O2•- and hydrogen peroxide (H2O2) production was assessed by fluorescence microscopy and H2O2 production was confirmed by microplate reader. Hyperglycemia or Aβ1-40 alone did not affect cell viability in RBMEC. However, the simultaneous presence of high glucose and Aβ1-40 reduced cell viability and ΔΨm, and enhanced mitochondrial O2•- and H2O2 production. MitoTempo and PEG-SOD prevented Aβ1-40 toxicity. Interestingly, MBMEC presented a similar pattern of alterations with db/db cultures presenting higher susceptibility to Aβ1-40. Overall, our results show that high glucose levels increase the susceptibility of brain microvascular endothelial cells to Aβ toxicity supporting the idea that hyperglycemia is a major risk factor for vascular injury associated with AD.
CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal Department of Life Sciences - Faculty of Sciences and Technology, University of Coimbra, Coimbra, Portugal.
Cristina
C
Carvalho
Paige S
PS
Katz
Somhrita
S
Dutta
Prasad V G
PV
Katakam
Paula I
PI
Moreira
David W
DW
Busija
D016229:Amyloid beta-Peptides / Q000633:toxicity*; D000818:Animals; D001921:Brain / Q000473:pathology*; D002478:Cells, Cultured; D004198:Disease Susceptibility / Q000209:etiology; D042783:Endothelial Cells / Q000187:drug effects*; D020690:GTPase-Activating Proteins; D005947:Glucose / Q000494:pharmacology; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics; D006861:Hydrogen Peroxide / Q000378:metabolism; D006943:Hyperglycemia / Q000139:chemically induced / Q000235:genetics / Q000473:pathology*; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects / Q000235:genetics; D051379:Mice; D008817:Mice, Mutant Strains; D010446:Peptide Fragments / Q000633:toxicity*; D010455:Peptides / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D054411:Receptors, Leptin / Q000235:genetics; D013997:Time Factors
D016229:Amyloid beta-Peptides; C539620:Dock7 protein, mouse; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D010446:Peptide Fragments; D010455:Peptides; D017382:Reactive Oxygen Species; D054411:Receptors, Leptin; C078592:amyloid beta-protein (1-40); C515447:leptin receptor, mouse; D006861:Hydrogen Peroxide; D005947:Glucose
Alzheimer's disease; amyloid-β peptide; brain endothelial cells; mitochondria; type 2 diabetes