The Effect Of GPR30on Endothelial Dysfunction In Diabetic Rat And High Glucose-induced Damage Of Endothelial Cells

BackgroundDiabetes mellitus can change the cardiovascular structure and function inpostmenopausal women, thereby increasing the incidence of cardiovasculardisease and mortality in postmenopausal women. Therefore, the use of estrogenreplacement therapy (HRT) is considered as the effective measure to theprevention and treatment of coronary heart disease and can significantly reducethe incidence of diabetes.However, HRT may also cause sider effects. The Gprotein-coupled and seven-transmembrane receptor, GPR30, is now widelyrecognized as an estrogen receptor (ER). G1(1nM-10μM) induced strongrelaxation of the aortic rings from the OVX rats in a dose-dependent manner.The vascular relaxation induced by G1was partly abolished by L–NAME. Theresults showed that the relaxant responses to GPR30agonists were nitric oxide(NO) mediated. The slow reactions of hyperglycemia to endothelial cells results in insufficient NO and damage on endothelial cells. Endothelial dysfunction isassociated with decreased NO availability and loss of NO production. Deletionof the G protein-coupled receptor30impairs glucose tolerance,reduces bonegrowth,increases blood pressure,and eliminates estradiol-stimulated insulinrelease in female GPR30(-/-) mice[1]. So, we postulated that GPR30mayattenuate endothelial dysfunction associated with diabetes. Therefore, we aimedto determine whether GPR30can attenuate endothelial dysfunction in diabeticrats and protect endothelial cells from high glucose-induced damage, and if so,to elucidate the signaling pathway involved.MethodsWe assessed the role of the endothelium in the responses to the GPR30agonists, G1, on thoracic aorta from ovariectomized (OVX) and OVX diabeticrats and on cultured endothelial cells damaged by high glucose. G1-inducedeffect was evaluated in vitro and in vivo. Experimental analyses were performedby using wire myography, colorimetric method，PI-Hoechst33258dyeing，MTT，immunofluorescence dyeing, and Western blot, et al.ResultsThe GPR30agonist G1induced a dose-dependent vasodilation in thethoracic aorta of the diabetic OVX rats, which was partially attenuated by thenitric oxide synthase (NOS) inhibitor, nitro-L-arginine methylester (L-NAME)and the GPR30-selective antagonist G15. Dose-dependent vasoconstrictiveresponses to phenylephrine were attenuated significantly in the rings of thethoracic aorta following the acute G1administration in the diabetic OVX rats.This effect of G1was abolished partially by L-NAME and G15. The acuteadministration of G1increased significantly the eNOS activity and the concentration of NO in the endothelial cells exposed to high glucose. G1treatment induced an enhanced endothelium-dependent relaxation toacetylcholine (ACh) in the diabetic OVX rats. Further examination revealed thatG1induced vasodilation and endothelial protection effect in the diabetic OVXrats by increasing the phosphorylation of eNOS and Akt.Conclusions1. GPR30can attenuate endothelial dysfunction associated with diabetes andprotect high glucose-induced damage of endothelial cells；2. The PI3K/Akt/eNOS pathway is required for the protective effect of GPR30.