ABSTRACT
This study was designed to investigate the possible role of Phosphatidylinositol-3 kinase (PI3K) and endothelial nitric oxide synthase (eNOS) in obesity-induced vascular endothelium dysfunction. Wistar rats were fed high fat diet (HFD) for 12 weeks to induce obesity. HFD induce obesity significantly increased parameters employed viz body weight, basal metabolic index (BMI), total fat pad and lipid profile. Furthermore vascular endothelial dysfunction was assessed in terms of decrease in endothelium dependent relaxation and serum nitrate/nitrite level and increase in mean arterial blood pressure. Atorvastatin (30mg/kg,i.p.) was employed in the present study as standard drug to improve vascular endothelial dysfunction. YS-49 (1.6 mg/kg, i.p.) a specific activator of PI3K and atorvastatin in obese rats significantly improves the lipid profile and markedly improved acetylcholine induced endothelium dependent relaxation, serum nitrite/nitrate concentration and mean arterial blood pressure. However, this ameliorative effect of YS-49 has been prevented by L-NAME (25 mg/kg, i.p.), an inhibitor of eNOS. Further wortmannin (100μg/kg, i.p.),a specific PI3K inhibitor improves the anthropometric parameters and lipid profile but did not show any significant effect on acetylcholine dependent relaxation, serum nitrate/nitrite level and mean arterial blood pressure. Therefore, it may be concluded that PI3K and eNOS pathway is dysregulated in obesity induced vascular endothelial dysfunction and YS-49, a PI3K activator improves vascular endothelial function in eNOS and nitric oxide dependent manner. Abbreviations (Ach): Acetylcholine, (Ang-II): Angiotensin II, (BMI): Body Mass Index, (Enos): Endothelial Nitric Oxide, Synthase, (HO-1): Heme Oxygenase, (Kcl): Pottesium Cloride, (MAP): Mean Arterial Pressure, (NO): Nitric Oxide, (PI3K): Phosphatidylinositol 3-Kinase, (SNP ): Sodium Nitroprusside, (VED): Vascular Endothelium Dysfunction
ABSTRACT
Endothelium, particularly pulmonary endothelium, is predisposed to injury by reactive oxygen species (ROS) and their derivatives. Heme oxygenase (HO) has been demonstrated to provide cytoprotective effects in models of oxidant-induced cellular and tissue injuries. In the present study, we investigated the effects of YS 49 against oxidant [tert-butylhydroperoxide (TBH) ]-induced injury using cultured sheep pulmonary artery endothelial cells (SPAECs). The viability of SPAECs was determined by quantifying reduction of a fluorogenic indicator Alamar blue. We found that TBH decreased cell viability in a time- and concentration-dependent manner. YS 49 concentration- and time-dependently increased HO-1 induction on SPAECs. As expected, YS 49 significantly decreased the TBH-induced cellular injury. In the presence of zinc protophorphyrin, HO-1 inhibitor, effect of YS 49 was significantly inhibited, indicating that HO-1 plays a protective role for YS 49. Furthermore, YS 49 showed free radical scavenging activity as evidenced by 1, 1-diphenyl-2-picrylhydrazyl (DPPH) and inhibition of lipid peroxidation. However, YS 49 did not inhibit apoptosis induced by lipopolysaccharide (LPS) in SPAECs. Taken together, HO-1 induction along with strong antioxidant action of YS 49 may be responsible for inhibition of TBH-induced injury in SPAECs.