雌二醇对牛视网膜毛细血管内皮细胞VEGF、HIF-1α的调控

Effect of 17β-estradiol on VEGF and HIF-1α mRNA expressions in bovine retinal vascular endothelial cells

目的观察在不同氧环境下,雌二醇(17β-estradiol,E2)对培养的牛视网膜毛细血管内皮细胞(bovine retinal vascular endothelial cells,BRECs)血管内皮生长因子(vascular endothelial growthfactor,VEGF)mRNA、低氧诱导因子-1(hypoxia-inducible factor-1α,HIF-1α)mRNA的影响。方法以培养的BRECs为模型,在正常氧及低氧(1%O2)条件下,给予不同生理浓度的E2及雌激素受体拮抗剂他莫昔芬,作用不同时间(8、24h),RT-PCR检测VEGF、HIF-1α mRNA的表达。结果①低氧条件下,BRECs的HIF-1α、VEGF mRNA表达较正常氧条件下明显增多(P<0.05),且VEGF、HIF-1α mRNA两者之间有明显的正相关性(r=0.82,P<0.05);②正常氧条件下,给予E2(10-12,10-10,10-8mol/L)作用24h,E2呈浓度依赖性促进BRECs的VEGF mRNA表达(P<0.05)。10-8mol/L E2作用8、24h,VEGF mR-NA表达量呈时间依赖性增多(P<0.05);而E2不影响HIF-1α mRNA的含量(P>0.05);③低氧条件下,给予E2(10-12,10-10,10-8mol/L)作用24h,E2呈浓度依赖性抑制BRECs的HIF-1α、VEGF mRNA表达(P<0.05)。10-8mol/LE2作用8、24h,HIF-1α、VEGF mRNA表达量呈时间依赖性降低(P<0.05);④他莫昔芬可逆转E2的作用。结论生理浓度的E2对VEGF mRNA具有双重调控作用:正常氧条件下促进BRECs VEGF表达;低氧条件下通过HIF-1α降低VEGF表达,并呈剂量、时间依赖性。

Objective To investigate the effect of the physiological level of estradiol on mRNA expressions of the vascular endothelial growth factor （VEGF） and hypoxia-inducible factor-1α （HIF-1α） in bovine retinal vascu1αr endothelial cells （BRECs） under different oxygen conditions. Methods mRNA expressions of VEGF and HIF-1α were determined by reverse transcription polymerase chain reaction （RT-PCR） in BRECs, with E2 （10^-12,10^-10,10^-8 mol/L）or phosphate-buffered saline （PBS） and estrogen receptor antagonist tamoxifen （ 10^- 7 mol/L） under normoxia and hypoxia after 8 hours and 24 hours. Results ① Under hypoxia, gene expressions of VEGF and HIF-1α mRNA in BRECs more significantly increased than in the controls（ P 〈0.05）. There were evident positive corre1αtions between the expressions of VEGF mRNA and HIF-1α mRNA（ r = 0.82）. ② After BRECs were treated with the indicated concentrations of E2 under normoxia for 24 hours, the expression of VEGF mRNA increased in a dose-dependent manner between 10^-12- -8 mol/L （P 〈 0.05）. After BRECs being treated with 10^-8 mol/L E2 8 hours and 24 hours, the expression of VEGF mRNA was increased in a time-dependent manner（P 〈0.05）. Whereas E2 did not affect the expression of HIF-1α mRNA（ P 〉 0.05）. ③After BRECs were treated with the indicated concentrations of E2 under hypoxia for 24 horns, the expressions of HIF-1α mRNA and VEGF mRNA decreased in a dose-dependent manner between 10^-12- -8 mol/L（ P 〈 0.05）. After BRECs were treated with 10^-8 mol/L E2 for 8 hours and 24 hours, the expressions of HIF-1α mRNA and VEGF mRNA decreased in a time-dependent manner （ P 〈 0.05）. ④ An overdose of tamoxifen （ 10^-7 mol/L） reversed the effect of E2 （10^-8 mol/L） （P 〈0.05）. Conclusions The physiological level of E2 has a contrast effect on VEGF mRNA in a dose- and time-dependent manner based on oxygen conditions. E2 increases the gene expression of VEGF in BRECs under normoxia, where- as E2 decreases the gene expression of VEGF in BRECs through HIF-1α under hypoxic conditions.