| Summary: | 碩士 === 南台科技大學 === 生物科技系 === 98 === Hypertension is a chronic medical condition in which the blood pressure is elevated and is closely related to many chronic diseases. Uncontrolled hypertension will cause damage to the arteries and result in hardening and thickening of the arteries (atherosclerosis), which can subsequently leads to stroke, coronary artery disease, heart failure, renal disease, great vessel disease , or other complications. Most of these diseases develop after middle age and the incidence rates increase with the increasing of age. Therefore, hypertension is a major cause of adult mortality and disability. It is also a critical public health issue. Main classes of antihypertensive drugs include diuretics, sympatholytics (adrenergic antagonists), direct vasodilators, angiotensin-converting enzyme (ACE inhibitors), angiotensin II receptor blockers (ARBs), calcium channel blockers, and etc. However, adverse effects of antihypertensive agents were widely concerned.
In an attempt to develop a new agent for hypertension, we investigated the water extract of Rhodiola (WtF) in spontaneous hypertensive rats (SHR). The present study design was designated to investigate the role of endogenous ß-endorphin in hypotensive action of water-soluble fraction from Rhodiola. The animal models were divided into four groups which included (1) sham group : received saline only; (2) sham spontaneous hypertension rats receiving Rhodiola water extracts (75 mg/kg); (3) spontaneous hypertension rats receiving both naloxone (5 mg/kg) and Rhodiola water extracts (75 mg/kg); and (4) adrenalecotomised spontaneous hypertension rats receiving Rhodiola water extracts (75 mg/kg). The concentration of β-endorphin in plasma or medium incubation adrenal medulla was measured using an enzyme-linked immunosorbent assay (ELISA).
In our study, oral intake of Rhodiola water extract (WtF) lowered blood pressure of conscious spontaneous hypertension rats (SHR) in a dose-dependent manner. According to previous published research paper, intravenous injections of Rhodiola sacra water extract (WtF) will also caused significant dose dependent hypotensive actions. In contrast, intravenous injections of n-butanol-soluble solution (BtF) from Rodiola sacra radix will induce little change in the blood pressure. It will caused transient and minimal decreased in blood pressure with high dose and tachycardia (the same dosages used in our study). The effective action of WtF was abolished by naloxone at the dose sufficient to block opioid receptors. Mediation of endogenous opioid can thus be considered. This view was further supported by the increase of
plasma β-endorphin using ELISA determination. Also, blood pressure lowering action of WtF was disappeared in SHR received adrenalectomy. Increase of β-endorphin secretion from adrenal gland by WtF can thus be considered. Moreover, mediation of cardiac output seems negligible because it was not changed by WtF in anesthetized SHR. Thus, decrease of peripheral blood resistance by WtF may be involved but this view needs more studies in the future.
From the obtained results, the present study suggested that water extract of Rhodiola (WtF) has the ability to lower blood pressure in spontaneous hypertension rats (SHR). Increase of β-endorphin secretion from adrenal gland is related to this action of Rhodiola water extract.
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