不同方法提取的铁皮石斛提取物对自发性高血压大鼠的降压作用及其机制研究

Antihypertensive Effect and Mechanism of Dendrobii Officinalis Caulis Extract by Different Extraction Methods in Spontaneously Hypertensive Rats

关键词:  铁皮石斛  醇水两提  自发性高血压  内皮素-1

Key words:  dendrobium officinale  ethanol-water extract  spontaneously hypertension rat(SHR)  endothelin-1

摘要:

目的 探讨不同方法提取的铁皮石斛提取物对自发性高血压（spontaneous hypertension rat，SHR）大鼠的降压作用及其机制。方法 32只SHR大鼠根据血压值随机分为水提组、醇水两提组（0.8 g·kg^-1·d^-1）、苯磺酸氨氯地平对照组（0.5 mg·kg^-1·d^-1）及模型组；另设8只Wistar大鼠为正常对照组。每周测量1次给药后2，24 h的血压。治疗8周后，用化学发光法检测血浆肾素活性（plasma renin activity，PRA）以及血浆醛固酮（aldosterone，ALD）、血管紧张素Ⅰ（AngiotensinI，AngⅠ）、血管紧张素Ⅱ（AngⅡ）的含量；用RT-qPCR法检测肾组织内皮素-1（ET-1）、血管紧张素Ⅱ 1型受体（angiotensinⅡ type 1 receptor，AT1R）的mRNA表达。结果 治疗8周，各治疗组给药后2 h的收缩压、舒张压均显著低于模型组（P<0.01），醇水两提组显著低于水提组、苯磺酸氨氯地平组（P<0.01）；醇水两提组、苯磺酸氨氯地平组给药后24 h的收缩压、舒张压醇均显著低于模型组（P<0.01）；停药3 d时，各治疗组收缩压/舒张压显著低于模型组（P<0.01），醇水两提组收缩压显著低于水提组、苯磺酸氨氯地平组（P<0.05或P<0.01）；疗程中治疗3~8周醇水两提组给药后2 h的收缩压、舒张压显著低于水提组（P<0.05或P<0.01），治疗6周和治疗8周醇水两提组给药后2 h的收缩压、舒张压显著低于苯磺酸氨氯地平组（P<0.01）；正常组与模型组以及各治疗组大鼠血浆中AngⅠ、AngⅡ、PRA和ALD的激素含量无显著差异；模型组AT1R、ET-1的mRNA表达高于正常组（P<0.05），水提组、醇水两提组、苯磺酸氨氯地平组AT1R的mRNA表达显著低于模型组（P<0.05或P<0.01），水提组ET-1的mRNA表达显著低于模型组（P<0.05或P<0.01）。结论 铁皮石斛不同提取方法的提取物均可显著降低SHR大鼠血压，铁皮石斛醇水两提提取物（0.8 g·kg^-1·d^-1）降压效果优于相同剂量的水提提取物，其降压作用优于苯磺酸氨氯地平（0.5 mg·kg^-1·d^-1）；铁皮石斛醇水两提提取物及水提取物对血浆AngⅡ激素含量没有影响，可能通过下调AngⅡ 1型受体起到调节血压作用。

Abstract:

OBJECTIVE To study the antihypertensive effect and mechanism of Dendrobii Officinalis Caulis extract by different extraction methods in spontaneously hypertensive rats. METHODS Thirty-two SHR rats were randomly divided into the water extract group, the ethanol-water extract group(0.8 g·kg^-1·d^-1), the amlodipine besylate tablets control group(0.5 mg·kg^-1·d^-1) and model group according to their blood pressure value, and eight Wistar rats were set as normal control group. The blood pressure was measured at 2, 24 h after administration once a week. After 8 weeks of treatment, plasma renin activity(PRA), and the contents of aldosterone(ALD), angiotensinⅠ (AngⅠ) and angiotensin Ⅱ (AngⅡ) in plasma were detected by chemiluminescence; the mRNA expression of endothelin-1 (ET-1) and angiotensin Ⅱ type 1 receptor (AT1R) in renal tissue was detected by RT-qPCR. RESULTS After 8 weeks of treatment, as to the Systolic pressure(SBP) and Diastolic pressure (DBP) at 2 h after administration, in each treatment groups were significantly lower than that in the model group (P<0.01), the ethanol-water extract group was significantly lower than the water extract group and the amlodipine besylate tablets control group at 2 hours after administration(P<0.01); as to the Systolic pressure(SBP) and Diastolic pressure (DBP) at 24 hours after administration, in the ethanol-water extract group and the amlodipine besylate tablets control group were significantly lower than that in the model group; at the third day after withdrawal, the SBP/DBP were significantly lower in each treatment group than that the model group(P<0.01), the SBP in the ethanol-water extract group was significantly lower than that in the water extract group and the amlodipine besylate tablets control group(P<0.05 or P<0.01); at the third to eighth weeks during the course of the treatment, the SBP/DBP in the ethanol-water extract group was significantly lower than the water extract group at 2hours after administration(P<0.05 or P<0.01), at the sixth and eighth week, the SBP/DBP at 2 hours after administration in the ethanol-water extract group were significantly lower than the amlodipine besylate tablets control group(P<0.01); there were no significant differences between the normal group, model group and each treatment groups of the levels of PRA, ALD, AngI and AngⅡ in plasma; the expression of the AT1R mRNA and the ET-1 mRNA in the model group were significantly higher than the normal group(P<0.05), the expression of the AT1R mRNA in the water extract group, ethanol-water extract group and amlodipine besylate tablets control group were significantly lower than in the model group(P<0.05 or P<0.01); the expression of ET-1 mRNA in the water extract group was significantly lower than in the model group(P<0.05 or P<0.01). CONCLUSION Extractions of dendrobium officinale with different extract methods can significantly reduce the blood pressure in SHR rats, the antihypertensive effect of ethanol-water extract(0.8 g·kg^-1·d^-1) was better than that of the same dosage of water extract group, the antihypertensive effect is higher than that of amlodipine besylate tablets (0.5 mg·kg^-1·d^-1); the ethanol-water extract and the water extract of dendrobium officinale have no effect on plasma AngⅡ level, and may regulate blood pressure by down-regulating angiotensin Ⅱ type I receptors(AT1R).