睾酮对肝细胞胰岛素敏感性的影响及分子机制

Effects of testosterone on insulin sensitivity in liver cells and related molecular mechanisms

目的 探讨睾酮对肝细胞胰岛素敏感性的影响及分子机制.方法 在体实验：21只成年C57BL/6雌鼠根据体重按完全随机法分为睾酮组（11只）及对照组（10只）,给药24周后处死.离体实验：将HepG2肝癌细胞分成3组：（1）10 9～10-5 mol/L睾酮处理0～36 h后胰岛素刺激;（2）101睾酮处理0～96 h后胰岛素刺激;（3）10-7 mol/L睾酮预处理36 h后胰岛素刺激,间隔4或6h后再次胰岛素刺激.Western印迹法检测鼠肝组织及HepG2细胞的蛋白激酶B（Akt）、糖原合成酶3β（GSK3β）活性及表达水平.结果 睾酮组鼠肝组织的Akt及GSK3β活性均明显低于对照组（分别为43.1％±3.2％比77.1％ ±6.7％,14.7％±6.7％比82.3％±2.0％,均P＜0.05）.胰岛素单次刺激HepG2细胞时,10-8～10-6 mol/L睾酮处理36 h的Akt、GSK3β活性均显著高于对照组（均P＜0.05）;但当睾酮处理时间延长至96 h或浓度升高至10-5 mol/L时,Akt、GSK3β的活性转趋下降;10-7mol/L睾酮组预处理36 h后胰岛素间隔6h二次刺激时,睾酮组的Akt、GSK3β活性均显著低于对照组（均P＜0.05）.结论 睾酮先增强后抑制肝细胞的胰岛素信号通路的转导,可能导致肝脏的胰岛素敏感性先增强后抑制,甚至转变为胰岛素抵抗.

Objective To explore the regulation of insulin sensitivity in liver cells by androgen signaling.Methods Eleven adult female C57BL/6 mice were injected daily with testosterone （group T） for 24 weeks.And 10 control mice received sesame oil only （group Con）.HepG2 liver cells were initially pretreated with different doses of testosterone （10-9 _ 10-5 mol/L） for 0-36 h or with 10-7 mol/L testosterone for 0-96 h followed by a stimulation of 100 nmol/L insulin for 15 min.Later HepG2 cells were pretreated with 10-7 mol/L testosterone for 36 h followed by a stimulation of 100 nmol/L insulin for 15 min and then a restimulation of 100 nmol/L insulin for 15 min at 4 h and 6 h interval respectively.Phosphorylation and protein expression of Akt and GSK3β in C57BL/6 mice liver tissues and HepG2 cells were analyzed by Western blot.Results The 24-week treatment of testosterone decreased the phosphorylation of Akt and GSK3β in C57BL/6 adipose and liver tissues （43.1% _± 3.2% vs 77.1% __ 6.7%,14.7% __ 6.7% vs 82.3% _± 2.0% respectively,P 〈 0.05）.Pretreatment with 10-8 _ 10-6 mol/L testosterone within 36 h obviously increased the phosphorylation of Akt and GSK3β （P 〈0.05）.However pretreatment with 10-5 mol/L within 36 h or with 10-7 mol/L for 96 h had no effect on the phosphorylation of Akt and GSK3β compared with control group （P 〉0.05）.Pretreatment with 10-7 mol/L testosterone for 36 h followed by insulin stimulation and restimulation after 6 h interval obviously decreased the phosphorylation of Akt and GSK3β （P 〈 0.05）.Conclusion Androgen signaling may contribute to insulin resistance in liver cells.