瘦素对体外培养肾小球RAAS和一氧化氮表达的影响

Effects of leptin on RAAS and nitric oxide production in isolated rat glomeruli

目的通过检测瘦素刺激后大鼠肾小球血管紧张素原(Agt)、血管紧张素Ⅱ受体1(AT1R)、内皮细胞一氧化氮合酶(eNOS) mRNA和蛋白表达水平及NO含量的变化,探讨瘦素对肾脏局部血流动力学的影响。方法分离大鼠肾小球,分为瘦素组(以3nmol/L瘦素刺激2h)和对照组,采用实时PCR、Western blot检测Agt、AT1R、eNOSmRNA和蛋白表达水平,硝酸盐还原酶法测定一氧化氮(NO)的含量。结果瘦素刺激后肾小球Agt、AT1R和eNOS mRNA表达增加[分别是对照组的(2.69±0.17)、(3.77±0.16)、(2.56±0.29)倍,P=0.024,0.018,0.044],蛋白表达增加[分别是对照组(2.06±0.10)、(2.67±0.08)、(1.61±0.13)倍,P=0.021,0.015,0.032],NO含量上升(P=0.000)。结论瘦素可能直接刺激肾小球局部肾素-血管紧张素系统表达及NO合成,参与肥胖状态下肾小球血流动力学紊乱。

Objective To investigate the changes in angiotensinogen （AGT）, angiotensin II type 1 receptor （AT1R）, endothelial nitric oxide synthase （eNOS） mRNA and protein expressions and nitric oxide （NO） content in the rat glomeruli in response to leptin stimulation. Methods The glorneruli isolated from male SD rats were stimulated with 3 nmol/L leptin for 2 h. Real-time PCR and Western blotting were performed to analyze the mRNA and protein expressions of AGT, AT1R and eNOS in the glomeruli, and nitrite concentration in the glomeruli was measured by nitrate reductase assay. Results In comparison with the control group, exposure to leptin increased the mRNA levels of AGT, ATR1 and eNOS in the isolated glomeruli by 2.69±0.17, 3.77±0.16 and 2.56±0.29 folds （P=-0.024, 0.018 and 0.044）, and their protein levels by 2.06_＋0.10, 2.67_＋0.08 and 1.61_＋0.13 folds （P=-0.021, 0.015 and 0.032）, respectively. The NO production in the glomeruli was also increased by 2.77±0.14 folds （P=-0.000） following leptin exposure. Conclusion Leptin exposure of isolated rat glomeruli directly causes activation of the internal renal renin-angiotensin system and enhanced NO production, suggesting that leptin plays a role in the pathogenesis of maladaptation in renal hemodynamics in obesity.