睾酮对血管平滑肌细胞中雄激素受体mRNA表达的调控

Regulation of androgen receptor mRNA expression by testosterone in cultured vascular smooth muscle cells

目的观察睾酮对雄性大鼠血管平滑肌细胞中雄激素受体mRNA表达的自身调控作用.方法贴块法培养雄性 SD大鼠胸主动脉血管平滑肌细胞(VSMCs),Northern印迹分析法检测细胞中雄激素受体mRNA水平;采用细胞计3H]-胸腺嘧啶掺入法观察调控过程中细胞数量和DNA合成变化情况.结果0～4 μmol/L睾酮与静止的VSMCs作用24 h,细胞内ARmRNA表达水平呈剂量相关性增加;生理水平睾酮(40nmol/L)与静止的VSMCs作用不同时间(0～24 h),细胞内ARmRNA表达水平在24 h时方有显著增加;实验过程中细胞数量及DNA合成速率均无明显改变.结论血管平滑肌细胞中存在睾酮对雄激素受体mRNA表达的自身上调作用,调控过程中细胞活力保持稳定.提示 VSMCs中睾酮对AR表达的调控作用部分需要转录水平的参与.

Objective To investigate the effects of testosterone exposure on androgen receptor (AR) mRNA expression in cultured vascular smooth muscle cells (VSMCs). Methods VSMCs were cultured from the thoracic aorta of male SD rats using explant method. The total RNA was extracted by one-step guanidine isothiocyanate method and subjected to Northern blotting analysis for determining AR mRNA level. The effect of testosterone on the viability and growth of VSMCs were studied by means of cell counting and tritiated thymidine incorporation assay. Results Testosterone treatment of the synchronized VSMCs for 24 h increased intracellular AR mRNA expression in a dose-dependent manner, with relative mRNA level of 97.67±7.22, 98.00±13.58, 143.33±10.99, 177.67±14.62 and 185.67±19.97 corresponding to testosterone doses of 0, 4 nmol/L, 40 nmol/L, 400 nmol/L and 4 μmol/L, respectively. Incubation of synchronized VSMCs with testosterone at a physiological level of 40 nmol/L for 24 h resulted in a mean of 30% up-regulation of AR mRNA level, compared with that of untreated cells. During AR up-regulation, testosterone had no significant effects on the cell number and DNA synthesis of VSMCs as measured by cell counting and tritiated thymidine incorporation assay. Conclusion Self-initiated up-regulation of AR mRNA expression occurs in synchronized VSMCs, which is independent of testosterone that influences apoptosis or growth rate of the cells, suggesting the involvement of AR in androgen regulational at the transcription level in VSMCs.