The predominant role of brain angiotensinogen and angiotensin in environmentally induced hypertension
The predominant role of brain angiotensinogen and angiotensin in environmentally induced hypertension
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DOI：
10.1016/s0167-0115(02)00156-8
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发表时间：
2002-12-31
影响因子：
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通讯作者：
Phillips, MI
中科院分区：
文献类型：
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作者：
Peng, JF;Kimura, B;Phillips, MI
长期暴露于寒冷环境（5 摄氏度/4 华氏度）的老鼠会出现高血压。这种寒冷诱发的高血压（CIH）是一种非遗传、非药理学、非手术的环境诱发高血压的大鼠模型。肾素-血管紧张素系统 (RAS) 似乎在 CIH 高血压的引发和/或维持中发挥作用。本研究的目的是评估中枢和外周循环 RAS 成分、血管紧张素原 (AGT)、血管紧张素转换酶 (ACE) 和血管紧张素 (Ang) II 在 CIH 中的作用。使用七十二只 Sprague-Dawley 成年雄性大鼠。 36只大鼠在5℃的冷藏室中饲养5周，另外36只在24℃的冷藏室中饲养5周。通过尾套记录收缩压（SBP）。暴露于寒冷的大鼠在 1 周内收缩压升高，并且这种升高在接下来的 2-5 周的寒冷暴露中显着 (p < 0.01)。在第 1、3 和 5 周处死三个亚组的冷处理大鼠和对照大鼠 (n = 12)。取出大脑和肝脏并保存血浆。从暴露于寒冷的第一周起，经冷处理的大鼠下丘脑和肝脏中的 AGT mRNA 显着增加，并且在整个暴露于寒冷的时间内保持不变（n = 4，p < 0.01）。冷处理大鼠和对照大鼠大脑、肝脏和血浆中的 AGT 蛋白水平没有显着差异 (p > 0.05, n = 4)。冷暴露 5 周的大鼠下丘脑 Ang 11 水平显着升高，而血浆 Ang 11 水平显着降低（n = 8，p < 0.05）。冷暴露 I 周的大鼠血浆 ACE 显着升高（p < 0.05，n = 12）。结果显示，暴露于冷环境的大鼠的大脑和外周之间 RAS 成分、AGT、ACE 和 Ang 11 的差异调节。我们得出的结论是，暴露于低温最初会增加血浆 RAS，但随着持续暴露于寒冷，大脑 RAS 可能通过持续的交感神经激活而维持高血压，这会增加新陈代谢，但也会导致血管收缩，从而导致高血压。 (C) 2002 Elsevier Science B.V. 保留所有权利。
Rats exposed chronically to a cold environment (5degreesC/4degreesF) develop hypertension. This cold-induced hypertension (CIH) is a non-genetic, non-pharmacological, non-surgical model of environmentally induced hypertension in rats. The renin-angiotensin system (RAS) appears to play a role in both initiating and/or maintaining the high blood pressure in CIH. The goal of the present study was to evaluate the role of central and peripheral circulating RAS components, angiotensinogen (AGT), angiotensin-converting enzyme (ACE) and angiotensin (Ang) II, in CIH. Seventy-two Sprague-Dawley adult male rats were used. Thirty-six rats were kept in cold room at 5degreesC while the other 36 were at 24degreesC as controls for 5 weeks. Systolic blood pressure (SBP) was recorded by tail cuff. The SBP was increased in rats exposed to cold within 1 week, and this increase was significant for the next 2-5 weeks of the cold exposure (p < 0.01). Three subgroups of the cold-treated and control rats (n = 12) were sacrificed at 1, 3 and 5 weeks. The brain and liver were removed and plasma was saved. The AGT mRNA significantly increased in the hypothalamus and liver in cold-treated rats from the first week of exposure to cold, and was maintained throughout the time of exposure to cold (n = 4, p < 0.01). The AGT protein levels in the brain, liver and plasma did not differ significantly between cold-treated and control rats (p > 0.05, n = 4). The hypothalamic Ang 11 levels were significantly increased, whereas plasma Ang 11 levels significantly decreased, in the rats of 5 weeks of cold exposure (n = 8, p < 0.05). Plasma ACE significantly increased in the rats of I week of cold exposure (p < 0.05, n = 12). The results show differential regulation of RAS components, AGT, ACE and Ang 11, between brain and periphery in cold-exposed rats. We conclude that the exposure to low temperature initially increases plasma RAS but with continuous exposure to cold, the brain RAS maintains the hypertension, probably by sustained sympathetic activation, which would provide increased metabolism but also vasoconstriction leading to hypertension. (C) 2002 Elsevier Science B.V. All rights reserved.