Endothelial damage due to impaired nitric oxide bioavailability triggers cerebral aneurysm formation in female rats

OBJECTIVE: Epidemiological data indicate a high incidence of cerebral aneurysms in postmenopausal women. To elucidate the pathogenesis of cerebral aneurysms, we focused on the contribution of endothelial damage in rats.

METHODS: We induced estradiol deficiency by oophorectomy (OVX), hypertension, or both, and hemodynamic stress in 7-week-old female Sprague-Dawley rats. They were then given hormone-replacement therapy with 17beta-estradiol or an angiotensin II type 1 receptor blocker (ARB). The effects of estradiol, angiotensin II type 1 receptor blocker, or both on cultured endothelial cells were also examined.

RESULTS: The number of anomalously shaped endothelial cells was higher in OVX than hypertensive rats (P < 0.05). Rats subjected to hypertension and OVX exhibited a marked increase in the incidence of saccular cerebral aneurysms. Estradiol or angiotensin II type 1 receptor blocker treatment reduced this incidence (P < 0.05). The endothelial nitric oxide synthase (eNOS) mRNA level in the intracranial artery of OVX and hypertensive and OVX rats was low (P < 0.05). Immunohistochemically, the expression of eNOS and estrogen receptor alpha (ERalpha) in the vascular wall of hypertensive and OVX rats was decreased; angiotensin II and the nicotinamide adenine dinucleotide phosphate oxidase subunits nicotinamide adenine dinucleotide phosphate oxidase 4 and p22phox were strongly expressed in cerebral aneurysms. In the absence of estradiol, eNOS was downregulated and nicotinamide adenine dinucleotide phosphate oxidase expression was increased in endothelial cells; angiotensin II augmented these phenomena. The regulation of eNOS was mediated by ERalpha. These results suggest that estrogen deficiency induces endothelial dysfunction and reactive oxygen species generation, triggering endothelial damage that leads to cerebral aneurysms and that hypertension is an additional risk factor.

CONCLUSION: A therapy targeted at the endothelium and management of hypertension may help to prevent cerebral aneurysms.

Medienart:

E-Artikel

Erscheinungsjahr:

2009

Erschienen:

2009

Enthalten in:

Zur Gesamtaufnahme - volume:27

Enthalten in:

Journal of hypertension - 27(2009), 6 vom: 27. Juni, Seite 1284-92

Sprache:

Englisch

Beteiligte Personen:

Tamura, Tetsuya [VerfasserIn]
Jamous, Mohammad A [VerfasserIn]
Kitazato, Keiko T [VerfasserIn]
Yagi, Kenji [VerfasserIn]
Tada, Yoshiteru [VerfasserIn]
Uno, Masaaki [VerfasserIn]
Nagahiro, Shinji [VerfasserIn]

Links:

Volltext

Themen:

11128-99-7
31C4KY9ESH
4TI98Z838E
Angiotensin II
Angiotensin II Type 1 Receptor Blockers
Benzimidazoles
Biphenyl Compounds
Candesartan cilexetil
DNA Primers
EC 1.14.13.39
EC 1.6.3.-
Estradiol
Journal Article
NADPH Oxidases
Nitric Oxide
Nitric Oxide Synthase Type III
Nos3 protein, rat
R85M2X0D68
RNA, Messenger
Research Support, Non-U.S. Gov't
Tetrazoles

Anmerkungen:

Date Completed 25.08.2009

Date Revised 16.11.2017

published: Print

Citation Status MEDLINE

doi:

10.1097/HJH.0b013e328329d1a7

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM187284873