Vascular endothelial insulin resistance (IR) is an important risk factor in the development of vascular complications in diabetes. Prolonged endoplasmic reticulum stress (ERS) contributes to the development and progression of endothelial IR. The current study assessed the effects and mechanism of nebivolol on vascular IR in Goto-Kakizaki (GK) rats and endothelial IR induced by high glucose (33.3 mmol/L) associated with high insulin (10-7 mol/L) in human aortic endothelial cells (HAECs). Rats were divided into Wistar, Wistar + Neb (Wistar rats treated with nebivolol, 10 mg/kg, ig), GK, and GK + Neb (GK rats treated with nebivolol, 10 mg/kg, ig). GK rats showed hyperglycemia, dyslipidemia, impaired glucose homeostasis, metabolic IR, reduced relaxation to insulin, and lower serum nitric oxide (NO) level. Treatment with nebivolol for 4 months ameliorated insulin's vasorelaxation and NO production, and relieved dyslipidemia in GK rats. Additionally, nebivolol increased glucose uptake and NO level in the endothelial IR group in vitro. Nebivolol increased aortic expressions of IRS-1/PI3K/Akt/eNOS relative proteins and GLUT4 and reduced expressions of ERS markers (ATF6, GRP78, and CHOP, p-JNK/JNK). Furthermore, both nebivolol and TUDCA (ERS inhibitor) alleviated the attenuated IRS-1PI3K/Akt/eNOS pathway and enhanced ERS in HAECs IR. Tunicamycin (ERS inducer) not only induced endothelial IR but also blocked nebivolol's alleviation on the IRS-1PI3K/Akt/eNOS pathway and ERS. Nebivolol ameliorated endothelial IR partially by inhibiting ERS and then regulating the IRS-1/PI3K/Akt/eNOS signal.
Keywords: GK rats; HAECs; IRS-1/PI3K/Akt/eNOS; TUDCA; Tunicamycin.