title: Central cardiovascular circuits contribute to the neurovascular dysfunction in angiotensin II hypertension.
abstract: Hypertension, a powerful risk factor for stroke and dementia, has damaging effects on the brain and its vessels. In particular, hypertension alters vital cerebrovascular control mechanisms linking neural activity to cerebral perfusion. In experimental models of slow-developing hypertension, free radical signaling in the subfornical organ (SFO), one of the forebrain circumventricular organs, is critical for the hormonal release and sympathetic activation driving the elevation in arterial pressure. However, the contribution of this central mechanism to the cerebrovascular alterations induced by hypertension remains uncertain. We tested the hypothesis that free radical production in the SFO is involved in the alterations in cerebrovascular regulation produced by hypertension. In a mouse model of gradual hypertension induced by chronic administration of subpressor doses of angiotensin II (AngII), suppression of free radicals in the SFO by overexpression of CuZn-superoxide dismutase (CuZnSOD) prevented the alteration in neurovascular coupling and endothelium-dependent responses in somatosensory cortex induced by hypertension. The SFO mediates the dysfunction via two signaling pathways. One involves SFO-dependent activation of the paraventricular hypothalamic nucleus, elevations in plasma vasopressin, upregulation of endothelin-1 in cerebral resistance arterioles and activation of endothelin type A receptors. The other pathway depends on activation of cerebrovascular AngII type 1 (AT1) receptors by AngII. Both pathways mediate vasomotor dysfunction by inducing vascular oxidative stress. The findings implicate for the first time the SFO and its efferent hypothalamic pathways in the cerebrovascular alterations induced by AngII, and identify vasopressin and endothelin-1 as potential therapeutic targets to counteract the devastating effects of hypertension on the brain.
authors.affiliation: Department of Neurology and Neuroscience, Division of Neurobiology, Weill Cornell Medical College, New York, New York 10021, USA.
authors.forename: Carmen
authors.initials: C
authors.lastname: Capone
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Faraco
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Peterson
authors.forename: Christal
authors.initials: C
authors.lastname: Coleman
authors.forename: Josef
authors.initials: J
authors.lastname: Anrather
authors.forename: Teresa A
authors.initials: TA
authors.lastname: Milner
authors.forename: Virginia M
authors.initials: VM
authors.lastname: Pickel
authors.forename: Robin L
authors.initials: RL
authors.lastname: Davisson
authors.forename: Costantino
authors.initials: C
authors.lastname: Iadecola
mesh_terms: D000804:Angiotensin II / Q000502:physiology* / Q000633:toxicity*; D000818:Animals; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D004730:Endothelium, Vascular / Q000378:metabolism / Q000473:pathology; D018014:Gene Transfer Techniques; D006973:Hypertension / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D017382:Reactive Oxygen Species / Q000378:metabolism; D044140:Receptor, Angiotensin, Type 1 / Q000819:agonists / Q000502:physiology; D013356:Subfornical Organ / Q000187:drug effects / Q000503:physiopathology*
chemical_list: D017382:Reactive Oxygen Species; D044140:Receptor, Angiotensin, Type 1; D000804:Angiotensin II