[Catalpol protect diabetic vascular endothelial function by inhibiting NADPH oxidase]

The aim of the present study was to evaluate the protective effect of catalpol on vascular endothelial function in STZ-induced type 2 diabetes mellitus (T2DM) rats. 40 high-fat diet with STZ-induced diabetes rats were randomly divided into model group, catalpol low-dose, middle-dose and high-dose group (10, 50, 100 mg x kg(-1) x d(-1)), 10 normal Wistar rats were used as the normal group. The normal and model groups were given an equivalent amount of saline. All reagents were administered by oral gavage for 6 weeks. After 6 weeks, blood glucose and lipids were detected by an automatic biochemical analyzer. The endothelium-dependent vasodilation response of thoracic aortar was detected. The pathological changes of the thoracic aorta were observed by HE staining. Ser- um nitric oxide (NO), 8-iso prostaglandin F2α (8-iso-PGF2α) and superoxide dismutase (SOD) were detected by ELISA. Reactive oxygen species (ROS) level of thoracic aorta was detected by fluorescence method. The expression of Nox4 and p22phox mRNA and protein in aortic tissue were detected by RT-PCR and Western-blot respectively. After catalpol treatment, endothelial damage of thoracic aorta was attenuated significantly; ROS level of thoracic aorta and serum level of 8-iso-PGF2α were decreased significantly; serum NO and SOD levels were remarkably elevated; expression of Nox4, p22phox mRNA and protein in thoracic aorta were significantly reduced (P < 0.05). Therefore, catalpol has protective effect on endothelial of T2DM, its mechanism may be associated with the down-regulation of Nox4 and p22phox expression, inhibiting oxidative stress reaction response.