Abstract
Resistin, a novel adipokine, was recently suggested to be involved in the development of endothelial dysfunction. However, the mechanisms of how resistin works are still unknown. This study was performed to investigate the relationship between resistin and phosphatidylinositol 3-kinase (PI3K), with the aim of gaining insight to the mechanisms by which resistin induces changes of secretion function of vascular endothelium. This study was conducted on 60 male 4-week-old Sprague-Dawley rats, which were randomly divided into four groups: resistin group (RS; n = 8), normal saline group (NS; n = 8), high-fat diet group (HF; n = 36), and control group (CO; n = 8). The resistin group was administered two injections of rat recombinant resistin. The diet-induced hyperresistinemia rats were selected from the HF group after the HF group was administered a high-fat diet for 8 weeks. The diet-induced hyperresistinemia rats were randomized into the antibody group (AB; n = 8) and hyperresistinemia group (HR; n = 8). The antibody group was given injections of resistin antibody twice per day and for 3 days. Immunohistochemistry was employed to examine the expression of PI3K p85α subunit and endothelial nitric oxide synthase (eNOS) in thoracic artery endothelium. In the resistin group, the levels of endothelin (ET), plasminogen activator inhibitor (PAI), and von Willebrand factor (vWF) were higher and NO was lower than those in the normal saline group. The NO level increased and ET, PAI, and vWF levels decreased in the antibody group when compared with the hyperresistinemia group. After administration of resistin antibody, the expression of PI3Kp85α and eNOS proteins in the antibody group was significantly increased but still differed significantly from those in the control group. PI3K grey value was correlated with resistin, PAI-1, vWF, NO, and the expression of eNOS (p < .05), after controlling for the effect of insulin. Resistin can affect the protein expression of PI3Kp85α, stimulate release of PAI-1, vWF, and ET, and down-regulate eNOS. The effect of resistin on PI3K signaling pathway might contribute to the development of endothelial secretion dysfunction in young rats.