Norepinephrine promotes oxidative stress in vascular adventitial fibroblasts via PKC/NFκB-mediated NOX2 upregulation

Background: Sympathetic overactivity is closely associated with vascular remodeling. Sympathetic fibers dominantly innervate the adventitia of arteries rather than tunica media. Vascular adventitial fibroblasts (VAFs) play crucial roles in vascular remodeling. However, the link between sympathetic overactivity and VAF proliferation and migration is unknown.

Methods: Primary VAFs were isolated from the thoracic aorta of spontaneously hypertensive rats and Wistar-Kyoto rats. Norepinephrine (NE) bitartrate monohydrate was applied to VAFs to simulate the sympathetic overactivity.

Results: NE increased NADPH Oxidase (NOX) 2 expression and superoxide level, which were almost abolished by NOX2 Inhibitor GSK2795039 or α-adrenoceptor antagonist prazosin, but not significantly affected by NOX1 Inhibitor ML171, NOX4 Inhibitor GLX351322 or β-adrenoceptor antagonist propranolol. Superoxide scavenger tempol or NOX2 Inhibitor GSK2795039 attenuated NE-induced VAF proliferation and migration. NE promoted protein kinase C (PKC) phosphorylation and NFκB-p65 nuclear translocation. Either PKC Inhibitor Go6983 or NFκB inhibitor BAY11-7082 attenuated NE-induced NOX activation, NOX2 upregulation, superoxide production, proliferation and migration.

Conclusion: NE promotes oxidative stress by α-receptor/PKC/NFκB-mediated NOX2 upregulation, which contributes to proliferation and migration of VAFs.

NADPH oxidase; Norepinephrine; hypertension; migration; oxidative stress; proliferation; vascular adventitial fibroblasts; vascular remodeling.