Circulating angiotensin II gains access to the hypothalamus and brain stem during hypertension via breakdown of the blood-brain barrier

Vinicia Campana Biancardi, Sook Jin Son, Sahra Ahmadi, Jessica A. Filosa, Javier E. Stern

Research output: Contribution to journalArticle

98 Citations (Scopus)

Abstract

Angiotensin II-mediated vascular brain inflammation emerged as a novel pathophysiological mechanism in neurogenic hypertension. However, the precise underlying mechanisms and functional consequences in relation to blood-brain barrier (BBB) integrity and central angiotensin II actions mediating neurohumoral activation in hypertension are poorly understood. Here, we aimed to determine whether BBB permeability within critical hypothalamic and brain stem regions involved in neurohumoral regulation was altered during hypertension. Using digital imaging quantification after intravascularly injected fluorescent dyes and immunohistochemistry, we found increased BBB permeability, along with altered key BBB protein constituents, in spontaneously hypertensive rats within the hypothalamic paraventricular nucleus, the nucleus of the solitary tract, and the rostral ventrolateral medulla, all critical brain regions known to contribute to neurohumoral activation during hypertension. BBB disruption, including increased permeability and downregulation of constituent proteins, was prevented in spontaneously hypertensive rats treated with the AT1 receptor antagonist losartan, but not with hydralazine, a direct vasodilator. Importantly, we found circulating angiotensin II to extravasate into these brain regions, colocalizing with neurons and microglial cells. Taken together, our studies reveal a novel angiotensin II-mediated feed-forward mechanism during hypertension, by which circulating angiotensin II evokes increased BBB permeability, facilitating in turn its access to critical brain regions known to participate in blood pressure regulation.

Original languageEnglish (US)
Pages (from-to)572-579
Number of pages8
JournalHypertension
Volume63
Issue number3
DOIs
StatePublished - Mar 1 2014

Fingerprint

Blood-Brain Barrier
Angiotensin II
Hypothalamus
Brain Stem
Hypertension
Permeability
Inbred SHR Rats
Brain
Hydralazine
Solitary Nucleus
Losartan
Paraventricular Hypothalamic Nucleus
Encephalitis
Vasodilator Agents
Fluorescent Dyes
Blood Vessels
Proteins
Down-Regulation
Immunohistochemistry
Blood Pressure

Keywords

  • angiotensin II
  • blood-brain barrier
  • brain stem
  • hypertension
  • hypothalamus
  • receptor, angiotensin, type 1

ASJC Scopus subject areas

  • Internal Medicine

Cite this

Circulating angiotensin II gains access to the hypothalamus and brain stem during hypertension via breakdown of the blood-brain barrier. / Biancardi, Vinicia Campana; Son, Sook Jin; Ahmadi, Sahra; Filosa, Jessica A.; Stern, Javier E.

In: Hypertension, Vol. 63, No. 3, 01.03.2014, p. 572-579.

Research output: Contribution to journalArticle

Biancardi, Vinicia Campana ; Son, Sook Jin ; Ahmadi, Sahra ; Filosa, Jessica A. ; Stern, Javier E. / Circulating angiotensin II gains access to the hypothalamus and brain stem during hypertension via breakdown of the blood-brain barrier. In: Hypertension. 2014 ; Vol. 63, No. 3. pp. 572-579.
@article{81d163dc1f904242b84625978fdfdfb6,
title = "Circulating angiotensin II gains access to the hypothalamus and brain stem during hypertension via breakdown of the blood-brain barrier",
abstract = "Angiotensin II-mediated vascular brain inflammation emerged as a novel pathophysiological mechanism in neurogenic hypertension. However, the precise underlying mechanisms and functional consequences in relation to blood-brain barrier (BBB) integrity and central angiotensin II actions mediating neurohumoral activation in hypertension are poorly understood. Here, we aimed to determine whether BBB permeability within critical hypothalamic and brain stem regions involved in neurohumoral regulation was altered during hypertension. Using digital imaging quantification after intravascularly injected fluorescent dyes and immunohistochemistry, we found increased BBB permeability, along with altered key BBB protein constituents, in spontaneously hypertensive rats within the hypothalamic paraventricular nucleus, the nucleus of the solitary tract, and the rostral ventrolateral medulla, all critical brain regions known to contribute to neurohumoral activation during hypertension. BBB disruption, including increased permeability and downregulation of constituent proteins, was prevented in spontaneously hypertensive rats treated with the AT1 receptor antagonist losartan, but not with hydralazine, a direct vasodilator. Importantly, we found circulating angiotensin II to extravasate into these brain regions, colocalizing with neurons and microglial cells. Taken together, our studies reveal a novel angiotensin II-mediated feed-forward mechanism during hypertension, by which circulating angiotensin II evokes increased BBB permeability, facilitating in turn its access to critical brain regions known to participate in blood pressure regulation.",
keywords = "angiotensin II, blood-brain barrier, brain stem, hypertension, hypothalamus, receptor, angiotensin, type 1",
author = "Biancardi, {Vinicia Campana} and Son, {Sook Jin} and Sahra Ahmadi and Filosa, {Jessica A.} and Stern, {Javier E.}",
year = "2014",
month = "3",
day = "1",
doi = "10.1161/HYPERTENSIONAHA.113.01743",
language = "English (US)",
volume = "63",
pages = "572--579",
journal = "Hypertension",
issn = "0194-911X",
publisher = "Lippincott Williams and Wilkins",
number = "3",

}

TY - JOUR

T1 - Circulating angiotensin II gains access to the hypothalamus and brain stem during hypertension via breakdown of the blood-brain barrier

AU - Biancardi, Vinicia Campana

AU - Son, Sook Jin

AU - Ahmadi, Sahra

AU - Filosa, Jessica A.

AU - Stern, Javier E.

PY - 2014/3/1

Y1 - 2014/3/1

N2 - Angiotensin II-mediated vascular brain inflammation emerged as a novel pathophysiological mechanism in neurogenic hypertension. However, the precise underlying mechanisms and functional consequences in relation to blood-brain barrier (BBB) integrity and central angiotensin II actions mediating neurohumoral activation in hypertension are poorly understood. Here, we aimed to determine whether BBB permeability within critical hypothalamic and brain stem regions involved in neurohumoral regulation was altered during hypertension. Using digital imaging quantification after intravascularly injected fluorescent dyes and immunohistochemistry, we found increased BBB permeability, along with altered key BBB protein constituents, in spontaneously hypertensive rats within the hypothalamic paraventricular nucleus, the nucleus of the solitary tract, and the rostral ventrolateral medulla, all critical brain regions known to contribute to neurohumoral activation during hypertension. BBB disruption, including increased permeability and downregulation of constituent proteins, was prevented in spontaneously hypertensive rats treated with the AT1 receptor antagonist losartan, but not with hydralazine, a direct vasodilator. Importantly, we found circulating angiotensin II to extravasate into these brain regions, colocalizing with neurons and microglial cells. Taken together, our studies reveal a novel angiotensin II-mediated feed-forward mechanism during hypertension, by which circulating angiotensin II evokes increased BBB permeability, facilitating in turn its access to critical brain regions known to participate in blood pressure regulation.

AB - Angiotensin II-mediated vascular brain inflammation emerged as a novel pathophysiological mechanism in neurogenic hypertension. However, the precise underlying mechanisms and functional consequences in relation to blood-brain barrier (BBB) integrity and central angiotensin II actions mediating neurohumoral activation in hypertension are poorly understood. Here, we aimed to determine whether BBB permeability within critical hypothalamic and brain stem regions involved in neurohumoral regulation was altered during hypertension. Using digital imaging quantification after intravascularly injected fluorescent dyes and immunohistochemistry, we found increased BBB permeability, along with altered key BBB protein constituents, in spontaneously hypertensive rats within the hypothalamic paraventricular nucleus, the nucleus of the solitary tract, and the rostral ventrolateral medulla, all critical brain regions known to contribute to neurohumoral activation during hypertension. BBB disruption, including increased permeability and downregulation of constituent proteins, was prevented in spontaneously hypertensive rats treated with the AT1 receptor antagonist losartan, but not with hydralazine, a direct vasodilator. Importantly, we found circulating angiotensin II to extravasate into these brain regions, colocalizing with neurons and microglial cells. Taken together, our studies reveal a novel angiotensin II-mediated feed-forward mechanism during hypertension, by which circulating angiotensin II evokes increased BBB permeability, facilitating in turn its access to critical brain regions known to participate in blood pressure regulation.

KW - angiotensin II

KW - blood-brain barrier

KW - brain stem

KW - hypertension

KW - hypothalamus

KW - receptor, angiotensin, type 1

UR - http://www.scopus.com/inward/record.url?scp=84894433066&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84894433066&partnerID=8YFLogxK

U2 - 10.1161/HYPERTENSIONAHA.113.01743

DO - 10.1161/HYPERTENSIONAHA.113.01743

M3 - Article

C2 - 24343120

AN - SCOPUS:84894433066

VL - 63

SP - 572

EP - 579

JO - Hypertension

JF - Hypertension

SN - 0194-911X

IS - 3

ER -