Angiotensin II induced cerebral microvascular inflammation and increased blood–brain barrier permeability via oxidative stress

• Published in: Neuroscience Vol. 171; no. 3; pp. 852 - 858
• Main Authors: Zhang, M, Mao, Y, Ramirez, S.H, Tuma, R.F, Chabrashvili, T
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 15.12.2010; Elsevier
• Subjects: angiotensin II; Angiotensin II - administration & dosage; Angiotensin II - toxicity; Animals; Biological and medical sciences; Blood-Brain Barrier - drug effects; Blood-Brain Barrier - metabolism; Blood-Brain Barrier - pathology; blood–brain barrier; Cerebral Arteries - drug effects; Cerebral Arteries - metabolism; Cerebral Arteries - pathology; Cerebral circulation. Blood-brain barrier. Choroid plexus. Cerebrospinal fluid. Circumventricular organ. Meninges; cerebrovascular; Drug Administration Schedule; Fundamental and applied biological sciences. Psychology; hypertension; inflammation; Inflammation Mediators - administration & dosage; Inflammation Mediators - toxicity; Male; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Microcirculation - drug effects; Microcirculation - physiology; Microvessels - drug effects; Microvessels - metabolism; Microvessels - pathology; Neurology; oxidative stress; Oxidative Stress - drug effects; Oxidative Stress - physiology; Permeability - drug effects; Vertebrates: nervous system and sense organs; nuclear factor-κβ; NF-κβ; endothelial cells; BBB; intravenously; cerebrovascular; Tempol; ICAM-1; vascular cell adhesion molecule-1; blood–brain barrier; inflammation; reactive oxygen species; 4-hydroxy-TEMPO; SHR; AngII; EB; EC; PBS; intraperitoneal; HSP; spontaneously hypertensive rat; intercellular cell adhesion molecule-1; i.p; i.v; VCAM-1; Evans Blue; angiotensin II; phosphate buffered saline; ROS; hypertension; heat shock proteins; oxidative stress; blood-brain barrier; Microcirculation; Oxidative stress; Renin angiotensin system; Central nervous system; Inflammation; Permeability; Angiotensin II; Blood brain barrier; Encephalon
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/j.neuroscience.2010.09.029

Abstract Although hypertension has been implicated in the pathogenesis of vascular disease, its role in inflammatory responses, especially in brain, remains unclear. In this study we found key mechanisms by which angiotensin II (AngII) mediates cerebral microvascular inflammation. C57BL/6 male mice were subjected to slow-pressor dose of AngII infusion using osmotic mini-pumps at a rate of 400 ng/kg/min for 14 days. Vascular inflammation in the brain was evaluated by analysis of leukocyte–endothelial interaction and blood–brain barrier (BBB) permeability. Results from intravital microscopy of pial vessels in vivo , revealed a 4.2 fold ( P <0.05, compared to vehicle) increase in leukocyte adhesion on day 4 of AngII infusion. This effect persisted through day 14 of AngII infusion, which resulted in a 2.6 fold ( P <0.01, compared to vehicle) increase in leukocyte adhesion. Furthermore, evaluation of BBB permeability by Evans Blue extravasation showed that Ang II significantly affected the BBB, inducing 3.8 times ( P <0.05, compared to vehicle) higher permeability. Previously we reported that AngII mediated hypertension promotes oxidative stress in the vasculature. Thus, we used the superoxide scavenger; 4-hydroxy-TEMPO (Tempol) to determine whether AngII via oxidative stress could contribute to higher leukocyte adhesion and increased BBB permeability. Tempol was given via drinking water (2 mmol) on day 4th following Ang II infusion, since oxidative stress increases in this model on day 4. Treatment with Tempol significantly attenuated the increased leukocyte/endothelial interactions and protected the BBB integrity on day 14 of AngII infusion. In conclusion, AngII via oxidative stress increases cerebral microvasculature inflammation and leads to greater immune-endothelial interaction and higher BBB permeability. This finding may open new avenues for the management of nervous system pathology involving cerebrovascular inflammation.