Icariin ameliorates angiotensin II-induced cerebrovascular remodeling by inhibiting Nox2-containing NADPH oxidase activation

Cerebrovascular smooth muscle cells (SMCs) hyperplasia is an important contributor to cerebrovascular remodeling during hypertension. The aim of present study was to investigate the effects of Icariin on cerebrovascular SMCs proliferation and remodeling and the underlying mechanisms. The results revealed that Icariin administration attenuated the enhanced basilar artery constriction in angiotensin II (AngII)-induced hypertension rat model, as well as the inhibition of basilar artery diameter reduction in response to AngII and phenylephrine. In addition, histological analyses showed that Icariin also significantly ameliorated basilar artery remodeling in AngII hypertensive rats. In human brain vascular SMCs (HBVSMCs), AngII-induced cell proliferation, migration and invasion were markedly inhibited by Icariin treatment. Moreover, Icariin treatment largely limited AngII-induced the increase of reactive oxygen species (ROS) production in HBVSMCs, which was closely associated with cell proliferation. Analysis of the mechanisms showed that Icariin decreased ROS production via inhibiting NADPH oxidase activity but not mitochondria-derived ROS production. Further, Icariin promoted Nox2 degradation and consequently reduced its protein expression. In conclusion, these findings demonstrate that Icariin attenuates cerebrovascular SMCs hyperplasia and subsequent remodeling through inhibiting Nox2-containing NADPH oxidase activation, suggesting Icariin may be a potential therapeutic agent to prevent the onset and progression of stroke.