The Effect Of Rosiglitazone On Secretion Of Transforming Growth Factor-β₁ And Apoptosis Of Vascular Smooth Musle Cell Of Rat In Vitro Culture

Objective To observe the effect of rosiglitazone on secretion of transforming growth factor-β1 (TGF-β1 ) and apoptosis of thoracic aorta vascular smooth musle cell (VSMC) of rat in vitro .Methods Primary cultures of rat VSMCs were obtained from enzymatically dissociated SD rat thoracic aorta, and experiments were performed using subconfluented cells at passages five through eight. VSMCs had been serum-starved for 24 hours before they were be used for experiments. VSMCs were then treated with rosiglitazone at 0, 25, 50, 100, 200,400umol/L,and the apoptosis of cell was observed by flow cytometry ,we had found that 100 umol/L was the best concentration to induce VSMCs to apoptosis.Treating VSMCs with rosiglitazone at the best concentration,then detected the level of TGF-β1 after 0, 0.5, 1, 3, 6, 18, 24 hour by enzyme-linked immunosorbent assay (ELISA),we had found that the level of TGF-β1 was the highest after 0.5 hour. In addition, a series of experiments included four groups: control group, 100 umol/L rosiglitazone, 100umol/L rosiglitazone + GW9662, 100 umol/L rosiglitazone + anti- TGF-β1 , and the levels of TGF-β1 were detected by ELISA, the apoptosis of VSMCs was observed by flow cytometry and TUNEL Apoptosis Detection Kit.Result Our studies found that the rate of apoptosis of VSMC treated with rosiglitazone was higher than control , and the rate would be higher with the increase of the concentration of rosiglitazone(P〈0.05), the number of apoptosis would be highest at 100 umol/L(P〈0.05), but the number would not increased even decreased while the concentration of rosiglitazone mount up over 100umol/L.From this we may conclude that rosiglitazone induced VSMCs apoptosis in a concentration-dependent fashion. Furthermore, the apoptosis of SMCs which added GW9662 before or TGF-β1 after rosiglitazone was lower than which only presented rosiglitazone at 100 umol/L either(P〈0.05). From this we also may conclude that the anti-TGF-β1 antibody and GW9662 both could reverse the apoptosis of VSMC induced by rosiglitazone. Our studies also found that the level of TGF-β1 in culture medium of rosiglitazone samples treated at 100umol/L were obviously higher than control(P〈0.05),and the level of TGF-β1 reached the highest in an half hour(P〈0.05)then decreased rapidly after top(P〈0.05). From this we may conclude that rosiglitazone was able to induce SMC secrecting TGF-β1 , and the release of TGF-β1 was fast. Moreover, in some experiments, GW9662 were added before rosiglitazone, the levels of TGF-β1 in their culture medium were manifest lower than in those only treated with rosiglitazone(P〈0.05). From this we also may conclude that the rapid release of TGF-β1 could be reversed by GW9662.Conclusion The apoptotic effect of rosiglitazone in VSMCs could be mediated by a mechanism that includes the activation of PPAR-γ,the rapid releasse of TGF-β1 and their interaction.