RESUMO
Objective To investigate the role of vitamin D receptor (VDR) in the protection of bufalin on podocyte injury induced by adriamycin (ADR).Methods (1) In vitro:the toxic effect of different concentrations of bufalin (10-9,10-8,10-7,104 mol/L) on podocyte was evaluated by lactate dehydrogenase (LDH) test;Annexin V-FITC and RT-PCR were utilized for podocyte apoptosis and VDR mRNA level respectively.Western blotting was used to analyze the protein expression of VDR and nephrin.SiRNA intervene was also applied to evaluate the role of VDR in bufalin's protective effect on podocyte injury induced by ADR.(2) In vitro:24 SD rats were randomly divided into three groups:control group,ADR group and ADR+bufalin group.TUNEL assay was applied to detect the apoptosis of podocytes in the kidney.Immunofluorescence and transmission electron microscope (TEM) were applied to analyze the expression of VDR and the ultrastructure of the glomerulus.Results Bufalin concentration lower than 10-7 mol/L had no toxicity on normal podocyte.Bufalin reduced the urinary protein excretion (P ＜ 0.05),alleviated the removal of podocyte foot processes and attenuated the changes in nephrin expression in the glomerulus of the adriamycin (ADR) rats (P ＜ 0.05).Bufalin notably inhibited the down-regulation of VDR in protein levels on the glomerulus of the ADR rats.Additionally,bufalin inhibited the down-regulation of VDR in both mRNA levels and protein levels (P ＜ 0.05),nephrin protein expression (P＜ 0.05),and apoptosis induced by ADR in cultured podocytes.Additionally,VDR specific siRNA intervene abolished the protective effect of bufalin in ADR-induced podocyte injury.Conclusion Bufalin can alleviate ADR-induced podocyte injury via enhancing VDR expression.