Microsphere embolism-induced endothelial nitric oxide synthase expression mediates disruption of the blood-brain barrier in rat brain.
Microsphere embolism (ME)-induced up-regulation of endothelial nitric oxide synthase (eNOS) in endothelial cells of brain microvessels was observed 2-48 h after ischemia. eNOS induction preceded disruption of the blood-brain barrier (BBB) observed 6-72 h after ischemia. In vascular endothelial cells, ME-induced eNOS expression was closely associated with protein tyrosine nitration, which is a marker of generation of peroxynitrite. Leakage of rabbit IgG from microvessels was also evident around protein tyrosine nitration-immunoreactive microvessels. To determine whether eNOS expression and protein tyrosine nitration in vascular endothelial cells mediates BBB disruption in the ME brain, we tested the effect of a novel calmodulin-dependent NOS inhibitor, 3-[2-[4-(3-chloro-2-methylphenyl)-1-piperazinyl]ethyl]-5,6-dimethoxy-1-(4-imidazolylmethyl)-1H-indazole dihydrochloride 3.5 hydrate (DY-9760e), which inhibits eNOS activity and, in turn, protein tyrosine nitration. Concomitant with inhibition of protein tyrosine nitration in vascular endothelial cells, DY-9760e significantly inhibited BBB disruption as assessed by Evans blue (EB) excretion. DY-9760e also inhibited cleavage of poly (ADP-ribose) polymerase as a marker of the apoptotic pathway in vascular endothelial cells. Taken together with previous evidence in which DY-9760e inhibited brain edema, ME-induced eNOS expression in vascular endothelial cells likely mediates BBB disruption and, in turn, brain edema.
Han
Feng
F
Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.
Shirasaki
Yasufumi
Y
Fukunaga
Kohji
K
D000818:Animals; D001812:Blood-Brain Barrier / Q000502:physiology*; D001921:Brain / Q000201:enzymology*; D002545:Brain Ischemia / Q000201:enzymology / Q000503:physiopathology; D002147:Calmodulin / Q000037:antagonists & inhibitors; D002560:Cerebrovascular Circulation; D004617:Embolism / Q000209:etiology / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000201:enzymology; D004790:Enzyme Induction; D007150:Immunohistochemistry; D007191:Indazoles / Q000494:pharmacology; D008863:Microspheres; D052250:Nitric Oxide Synthase Type III / Q000096:biosynthesis*; D051381:Rats
C109602:3-(2-(4-(3-chloro-2-methylphenyl)1-piperazinyl)ethyl)5,6-dimethoxy-1-(4-imidazolylmethyl)-1H-indazol dihydrochloride 3.5 hydrate; D002147:Calmodulin; D007191:Indazoles; D052250:Nitric Oxide Synthase Type III