铁皮石斛不同温度的提取物对自发性高血压大鼠降压作用研究

Study on the Antihypertensive Effect of Extract at Different Temperatures of Dendrobium Officinale on Spontaneous Hypertension Rats

关键词:  铁皮石斛  多糖含量  提取温度  自发性高血压

Key words:  Dendrobium officinale  polysaccharide content  extraction temperature  spontaneously hypertension rat

摘要:

目的 观察不同提取温度条件下的铁皮石斛水提取物对自发性高血压大鼠（spontaneous hypertension rat，SHR）的降压作用及其可能机制。方法 将♀♂各半，48只SHR大鼠随机分为铁皮石斛60℃水提组（0.8 g·kg^-1·d^-1）、100℃水提组（0.8 g·kg^-1·d^-1）、121℃水提组（0.8 g·kg^-1·d^-1）、60℃-100℃-121℃梯度温度水提组（0.8 g·kg^-1·d^-1）和阳性药组（0.5 mg·kg^-1·d^-1苯磺酸氨氯地平片）及模型组；另设8只Wistar大鼠为正常组。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）和血浆醛固酮（aldosterone，ALD）、血管紧张素Ⅰ（angiotensin Ⅰ，Ang Ⅰ）、血管紧张素Ⅱ（angiotensin Ⅱ，Ang Ⅱ）的含量；用RT-qPCR法检测肺组织血管紧张素转化酶（angiotensin converting enzyme，ACE）、肝组织血管紧张素原（angiotensinogen，AGT）、肾组织醛固酮合成酶（CYP11B2）、Ang Ⅱ 1型受体（angiotensinⅡ type 1 receptor，AT1R）、内皮素1（endothelin-1，ET-1）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），其中铁皮石斛各不同温度水提组降压幅度与阳性药组接近，各组间降压作用差异不大；治疗7~8周、停药3 d，各治疗组24 h后的收缩压显著低于模型组（P<0.05或P<0.01）；治疗7周、停药3 d，各治疗组24 h后的舒张压显著低于模型组（P<0.05或P<0.01）；铁皮石斛各不同温度提取组给药后24 h的降压幅度与阳性药组接近，且治疗8周以来各组间降压作用差异不大；正常组与模型组以及各治疗组大鼠血浆中Ang Ⅰ、Ang Ⅱ、PRA和ALD的激素含量无显著差异；模型组AT1R的mRNA水平高于正常组，100℃水提组、121℃水提组和阳性药组AT1R的mRNA水平与模型组比较显著降低（P<0.05）。结论 铁皮石斛不同温度水提取，多糖含量有一定差异，均能够显著降低SHR大鼠血压，其降压作用可能与下调AT1R有关，不同温度水提取降压效果相似，降压作用与西药降压药苯磺酸氨氯地平片接近，铁皮石斛降压疗效与多糖含量可能没有直接关联。

Abstract:

OBJECTIVE To observe the antihypertensive effect and its possible mechanism of extraction of Dendrobium officinale extracted at different temperatures on spontaneous hypertension rats(SHR). METHODS Half male and half female, totally 48 SHR rats were randomly divided into Dendrobium officinale 60℃ water extraction group(0.8 g·kg^-1·d^-1), 100℃ water extraction group(0.8 g·kg^-1·d^-1), 121℃ water extraction group(0.8 g·kg^-1·d^-1), 60℃-100℃-121℃ gradient temperature water extraction group(0.8 g·kg^-1·d^-1), positive drug group(0.5 mg·kg^-1·d^-1 amlodipine besylate tablets) and model group, and eight Wistar rats were set as normal 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), angiotensin I(Ang I) and angiotensin II(Ang II) in plasma were detected by chemiluminescence; the mRNA expression of angiotensin converting enzyme(ACE) in pulmonary tissue, angiotensinogen(AGT) in liver tissue, aldosterone synthetase(CYP11B2) in renal tissue, Ang Ⅱ type 1 receptor(AT1R), endothelin-1(ET-1) were detected by RT-qPCR. RESULTS After 8 weeks of treatment, the systolic pressure and diastolic pressure at 2 h after administration in each treatment groups were significantly lower than that in the model group(P<0.01), among them, the pressure relief of Dendrobium officinale in different temperature water extraction group was similar to that of the positive drug group, there was little difference in antihypertensive effect among groups; after 7-8 weeks of treatment and at the third day after withdrawal, the systolic blood pressure after 24 h in each treatment groups were significantly lower than that in the model group(P<0.05 or P<0.01); after 7 weeks of treatment and at the third day after withdrawal, the diastolic pressure after 24 h in each treatment groups were significantly lower than that in the model group(P<0.05 or P<0.01); the pressure relief at 24 h in Dendrobium officinale different temperature extraction group was similar to that of the positive drug group, and there was no significant difference in blood pressure reduction between groups in 8 weeks of treatment. There were no significant differences between the normal group, model group and each treatment groups of the levels of Ang I, Ang II, PRA and ALD in plasma; the expression of the AT1R mRNA in the model group were significantly higher than the normal group, the expression of the AT1R mRNA in the 100℃ water extraction group, 121℃ water extraction group and positive drug group were significantly lower than in the model group(P<0.05). CONCLUSION Extractions of Dendrobium officinale at different temperature can significantly reduce the blood pressure in SHR rats, while there is a difference in the polysaccharide content. And the antihypertensive effect may be related to the down-regulating AT1R, the effect of water extraction under different temperatures is similar, and the hypotensive effect is close to that of western medicine antihypertensive drug(amlodipine besylate tablets). The antihypertensive effect of Dendrobium officinale and polysaccharide content may not be directly related.