波生坦及氨氯地平对脱氧皮质酮-盐型高血压大鼠肾脏纤维化和微血管的影响

Impacts of bosentan and amlodipine on renal fibrosis and microvasculatures in rat models of hypertension induced by deoxycortico sterone acetate-salt

目的:比较波生坦和氨氯地平对脱氧皮质酮(DOCA)-盐型高血压大鼠(DHR)肾脏纤维化和微血管的影响,探讨内皮素-1(ET-1)在DHR肾脏损害中的作用及可能机制。方法:30只10周龄清洁级雄性SD大鼠,切除左侧肾脏,1周后存活24只,随机分成对照组、波生坦组、氨氯地平组和安慰剂组。对照组给予饮自来水,另3组予DOCA[50mg/(kg·周)]皮下注射,饮盐水,同时分别予波生坦、氨氯地平和安慰剂;5周时测定24h尿蛋白排泄量(24h-UPER)、血压、尿素氮(BUN)和血肌酐(Scr);处死后评估病理切片肾小球硬化和肾小管间质损害程度;观察转化生长因子β1(TGF-β1)和Smad7的表达,分析肾组织毛细血管指数和增生内皮细胞数。结果:与对照组相比,安慰剂组血压、24h-UPER增加,肾脏有较明显的组织学改变,肾内TGF-β1和Smad7的蛋白表达明显上调,波生坦能较显著地抑制上述异常(P<0.05)。氨氯地平虽显著抑制血压升高,但对肾脏损害指标似无改善(P>0.05)。各组肾功能指标在正常范围内。安慰剂组中肾小球毛细血管指数(GCI)和肾小管周毛细血管指数(PCI)和增生内皮细胞数较对照组明显减少,波生坦、氨氯地平均能显著增加毛细血管和新生毛细血管数(P<0.01),但氨氯地平组增加程度不如波生坦组,差异有统计学意义(P<0.05)。TGF-β1与GCI、PCI和增生内皮细胞数具有显著的负相关性。结论:ET-1在DHR肾脏损害中发挥重要作用,其机制可能为通过上调TGF-β1和Smad7蛋白表达及直接抑制新生血管形成,间接加速毛细血管毁损而加重肾缺血和肾损害。

Objective To investigate the impacts of bosentan and amlodipine on renal fibrosis and microvasculatures in deoxycorticosterone acetate （DOCA）-salt hypertension rats（DHR） model, as well as to explore the role and possible mechanism ofendothelin-1 （ET-1） on DHR renal damage. Methods Thirty male Srague-Dawley rats were uninephrectomized. One week postoperatively, 24 survival rats were randomly divided into 4 groups. One group served as control, while the other 3 groups were subcutaneously administered with DOCA 50 mg/（kg·week） and 1% drinking saline water. Simultaneously, the rats were treated with either amlodipine 20 mg/（kg·d）, bosentan 100 mg/（kg·d）, or placebo. After 5 weeks treatment, systolic blood pressure（SBP）, 24 h urinary protein excretion rate（24 h-UPER）, serum blood urea nitrogen（BUN）, creatinine（Scr） were determined. The expression of transforming growth factor （TGF-β1） and Smad7 in renal tissues were evaluated. The microvessel density and the number of proliferating endothelial cells were also counted. Results Enhanced 24 h-UPER, significant renal histopathological abnormality, upregnlation of TGF-β1 and Smad7 were observed in untreated DHR rats, compared with those in control group. All these abnormalities were ameliorated by bosentan.Yet,amlodipine did not demonstrate similiar efficacy. No significant abnormality of renal function was observed. The glomemlar capillary index （GCI） and peritubular capillary index（PCI） were significantly decreased in DHR groups than those in control group （P〈0.01）. The GCI and PCI in antihypertension drug-treated group were significantly higher than those in placebo group, but the GCI and PCI in bosentan group were significantly higher than those in amlodipine group（P〈0.05）.The numbers of glomendar and interstitial proliferating endothelial cells in all antihypertensive drug-treated groups were significantly higher than those in placebo group （P〈0.01）, but the numbers of proliferating endothelial cells in bosentan group were significantly higher than those in amlodipine-treated group（P〈0.05）. Conclusions ET-1 might play an important role in the progression of renal damage via upregulating the TGF-β1 and Smad7 expression, and directly inhibit the angiogenesis, thus in turn worsen the renal ischemia and renal damage via microvasculature disturbance.