The Role Of S1P Receptor On Citronellal Inhibits Vascular Function Injury In Type ? Diabetes Mellitus And Its Mechanism

BackgroundVascular endothelial dysfunction is the initial factor of various vascular complications induced by type 2 diabetes mellitus?T2DM?.Citronellal?CT?(C₁₀H₁₈O,3,7-dimethyl-6-octenal)is an acyclic monoterpene aldehyde extracted from citronella.Our previous studies have shown that CT can improve vascular endothelial dysfunction?ED?induced by atherosclerosis,but whether CT can improve vascular endothelial dysfunction induced by T2DM and its related mechanism has not been reported at home and abroad.Sphingosine-1-phosphate?S1P?is an important component of cell membrane,and is also an important target for the prevention and treatment of cardiovascular diseases,which can combine with S1P receptors and activate PI3K/AKT,ERK1/2 and other singal transduction pathways to regulate vascular growth and vascular tension.In this study,we established T2DM rats model and incubated human umbilical vein endothelial cells?HUVECs?with high glucose to investigate whether CT inhibits vascular function injury induced by T2DM through up-regulating the expression of S1P receptor in vascular endothelium.Objective?1?To determine the protective effect of CT on vascular endothelial dysfunction induced by type 2 diabetes mellitus.?2?To explore the occurrence mechanism of up-regulate S1P receptor expression mediating vascular endothelial dysfunction induced by type 2 diabetes mellitus.MethodMale Sprague-Dawley?SD?rats were fed with high fat and high sugar diet.T2DM rats model were established by intraperitoneal injection streptozotocin?STZ?and HUVECs incubating with high glucose were used to establish cells model.CT and S1P receptor antagonist?Fingolimod?were used to treat and intervene.All experiments were as follows:?1?Oil red O staining and hematoxylin-eosin?HE?staining was used to observe the morphological structure and microstructure changes of rat thoracic aorta;?2?The morphological changes of rat retinal arterioles were observed by fundus imaging;?3?The diameter changes and diastolic function of rat mesenteric arteries were detected by isolated microvascular culture in vitro;?4?The endothelium-dependent relaxation?EDR?function and endothelium-independent relaxation function of isolated thoracic aortic rings were detected by incubating isolated vascular rings in vitro;?5?The migration ability of HUVECs was detected by cell scratch test;?6?The expression of S1P receptor protein in rat thoracic aorta was detected by Western blot?WB?and immunohistochemical?IHC?staining;?7?The expression of S1P₁ and S1P₂ receptor protein in vascular tissue and HUVECs was detected by immunofluorescence?IFC?staining;?8?The content of nitric oxide?NO?,the content of malondialdehyde?MDA?and the activity of superoxide dismutase?SOD?in serum of rats were detected by Elisa kit.Result?1?The vascular endothelium of thoracic aorta of type 2 diabetic rats and HUVECs incubated with high glucose showed obvious tissue damage and structural changes.CT significantly inhibited tissue damage and structural changes.When CT and Fingolimod were intervened together,the protective effect of CT was significantly weakened.?2?Mesenteric arterioles and retinal arterioles of type 2 diabetic rats showed obvious tissue damage and structural and functional changes.CT significantly inhibited tissue injury and structural and functional changes.When CT and Fingolimod were intervened together,the protective effect of CT was significantly weakened.?3?The migration ability of HUVECs incubated with high glucose decreased significantly.CT significantly increased the migration ability of endothelial cells.When CT and Fingolimod were intervened together,the protective effect of CT was significantly weakened.?4?Endothelium-dependent vasodilation?EDR?function of thoracic aorta and vasodilation function of mesenteric arterioles were significantly decreased in type 2diabetic rats,and the release of NO from vascular endothelium was significantly decreased.CT significantly increased the EDR function of thoracic aorta and the diastolic function of mesenteric arterioles in type 2 diabetic rats,and increased the release of NO in serum.There was significant difference compared with T2DM group?P<0.05?.The protective effect of CT on vasodilation was significantly weakened when CT and Fingolimod were intervened together.?5?The content of S1P in thoracic aorta of type 2 diabetic rats decreased significantly.CT significantly increased the protein expression of S1P receptor.There was significant difference compared with T2DM group?P<0.05?.The protein expression of S1P decreased significantly when CT and Fingolimod were intervened together.?6?The protein expression level and fluorescence intensity of S1P₁ in HUVECs and vascular endothelium of thoracic aorta of type 2 diabetic rats decreased significantly.CT significantly increased the protein expression and fluorescence expression intensity of S1P₁receptor.There was significant difference compared with T2DM group?P<0.05?.The protein expression and fluorescence expression intensity of S1P₁ receptor decreased significantly when CT and Fingolimod were interfered together.?7?The content of MDA increased significantly and the activity of SOD decreased significantly in serum of type 2 diabetic rats.CT significantly decreased the content of MDA and increased the activity of SOD.There was significant difference compared with T2DM group?P<0.05?.The protective effect of CT on vascular endothelial oxidative injury was significantly weakened when CT and Fingolimod were intervened together.Conclusion?1?CT inhibits vascular endothelial dysfunction induced by type 2 diabetes mellitus.?2?The up-regulated expression of S1P₁ receptor is involved in the inhibitory effect of CT on vascular endothelial dysfunction induced by type 2 diabetes.