果糖诱导大鼠胰岛素抵抗和高血压的机制及人组织型激肽释放酶基因的治疗作用

Mechanisms of hypertension and insulin resistance in fructose-induced hypertensive rat model and therapeutic effects of human tissue kallikrein gene on them

目的 研究果糖诱导高血压合并高胰岛素血症、胰岛素抵抗时内皮素 1(ET -1)及其受体 (ETA)、血管紧张素Ⅱ受体 1(AT1)的变化和人组织型激肽释放酶 (HK )基因的治疗作用。方法雄性Sprague -Dawley (SD)大鼠饮用 10 %果糖水诱导形成高血压和胰岛素抵抗动物模型后 ,静脉注入含HKcDNA的重组质粒 (pcDNA HK )。监测血压 ,血清胰岛素及血糖等。 2周时处死动物 ,测定脏器中HK的表达及ET 1、ETA和AT1的表达情况。结果 饮高果糖水 2周后 ,动物血压、血胰岛素水平明显高于正常饮水组 ,静脉注射pcDNA HK后第 3天即可明显降低果糖诱导高血压大鼠的血压 ,最大降压效应在导入基因后第 14天 (达 15mmHg) ,其降压效应持续 3周以上。HK基因导入后第 2周 ,HK治疗组动物ET 1、ETA及AT1明显低于对照组 ,与正常组接近。并且在血压下降的同时 ,血胰岛素浓度亦明显降低。结论 动物高果糖饮水可导致高血压及高胰岛素血症 ,其机理可能与ET 1、ETA和AT1表达增加有关 ,HK基因的导入可能通过降低血管ET 1、ETA和AT1表达而降低血压 ,并纠正高血压伴随的高胰岛素血症 。

Objective To investigate the possible mechanism of high fructose-induced hypertension and therapeutic effects of human tissue kallikrein (HK) gene delivery on the hypertension as well as insulin resistance in fructose-induced hypertensive rats Methods Male Sprague-Dawley rats fed on high-fructose (10%) water to develop mild hypertensive models within 2 weeks Fructose-induced hypertensive and control rats were injected intravenously with a construct pl asmid containing the HK cDNA The caudal arterial pressure was measured twice a week for 5 weeks until the animals were sacrificed The blood was collected for determination of the levels of blood glucose, insulin and ET-1 Vascular ET-1 and ETA gene expressions were measured by RT-PCR Results Compared with control rats given normal water, the fructose-fed rats developed systolic hypertension and hyperinsulinemia after 2 weeks A single intravenous injection of pcDNA-HK resulted in a significant reduction in blood pressure beginning 3 days after injection and the effect lasted for 3 weeks It is very surprised that the levels of plasma insulin were reduced to normal levels in HK-treated rats, although all animals were kept in feeding with 10% fructose water But the rats in control had nothing changed compared with those before plasmid injection Although plasma ET-1 levels did not differ between the rat groups, urine ET-1 levels were significantly lower in these rats than in controls RT-PCR showed that fructose-fed rats with HK gene delivery had lower ET-1, ETA, AT 1 gene expression than control rats The expression of HK was detected in rat main organs by Western Blot and in blood and urine by ELISA in pcDNA-HK treated rats Conclusion These findings suggest that elevated vascular expression of ET-1 and ETA receptor genes may mediate the development of hypertension and hyperinsulinemia in rats fed a fructose-rich diet HK gene transfer may reduce dominantly blood pressure and high levels of plasma insulin in fructose-induced hypertensive rats with hyperinsulinemia through the reduction of vascular expression of ET-1, ETA and AT 1 gene, which raises the feasibility of applying HK gene to treat human hypertension with insulin resistance