Glucocorticoids act in the dorsal hindbrain to modulate baroreflex control of heart rate
Glucocorticoids act in the dorsal hindbrain to modulate baroreflex control of heart rate
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DOI：
10.1152/ajpregu.00345.2005
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发表时间：
2006-04-01
影响因子：
2.8
通讯作者：
Scheuer, DA
中科院分区：
文献类型：
--
作者：
Bechtold, AG;Scheuer, DA
全身皮质酮（Cort）调节心率和肾交感神经活动的动脉压力反射控制。由于压力感受器传入信号终止于皮质类固醇受体密集表达的后脑背侧（DHB），因此我们验证了DHB皮质受体的长时间激活会增加中点并降低有意识大鼠动脉压力反射控制心率的增益的假设。将Cort （DHB Cort）或硅橡胶（DHB Sham）的小颗粒（3-4 mg）放置在DHB表面，或通过将Cort颗粒放置在硬脑膜表面（dura Cort）来全身给药。在开始治疗后的每4天，对有意识的雄性Sprague Dawley大鼠进行心率反射控制。使用四参数逻辑函数分析动脉压与心率的关系图。治疗3 d后，DHB Cort大鼠的动脉压中点（123 +/- 2 mmHg）较DHB Sham （108 +/- 3 mmHg）和Dura Cort大鼠（109 +/- 2 mmHg, P < 0.05）升高。第4天，DHB Cort动物的基线动脉压（112 +/- 2 mmHg）高于DHB Sham （105 +/- 2 mmHg）和Dura Cort动物（106 +/- 2 mmHg, P < 0.05），动脉压中点仅在DHB Cort组显著高于平均动脉压。同样在第4天，DHB Cort的最大压力反射增加（2.72 +/- 0.12次中心dot min（-1）中心dot mmHg(-1)）相对DHB Sham和Dura Cort大鼠（3.51 +/- 0.28次和3.37 +/- 0.27次中心dot min（-1）中心dot mmHg(-1)）减少（P < 0.05）。我们的结论是，Cort在DHB中起作用，增加中点，减少心率反射功能的增益。
Systemic corticosterone (Cort) modulates arterial baroreflex control of both heart rate and renal sympathetic nerve activity. Because baroreceptor afferents terminate in the dorsal hindbrain (DHB), an area with dense corticosteroid receptor expression, we tested the hypothesis that prolonged activation of DHB Cort receptors increases the midpoint and reduces the gain of arterial baroreflex control of heart rate in conscious rats. Small (3-4 mg) pellets of Cort (DHB Cort) or Silastic (DHB Sham) were placed on the surface of the DHB, or Cort was administered systemically by placing a Cort pellet on the surface of the dura (Dura Cort). Baroreflex control of heart rate was determined in conscious male Sprague Dawley rats on each of 4 days after initiation of treatment. Plots of arterial pressure vs. heart rate were analyzed using a four-parameter logistic function. After 3 days of treatment, the arterial pressure midpoint for baroreflex control of heart rate was increased in DHB Cort rats (123 +/- 2 mmHg) relative to both DHB Sham (108 +/- 3 mmHg) and Dura Cort rats (109 +/- 2 mmHg, P < 0.05). On day 4, baseline arterial pressure was greater in DHB Cort (112 +/- 2 mmHg) compared with DHB Sham (105 +/- 2 mmHg) and Dura Cort animals (106 +/- 2 mmHg, P < 0.05), and the arterial pressure midpoint was significantly greater than mean arterial pressure in the DHB Cort group only. Also on day 4, maximum baroreflex gain was reduced in DHB Cort (2.72 +/- 0.12 beats center dot min(-1) center dot mmHg(-1)) relative to DHB Sham and Dura Cort rats (3.51 +/- 0.28 and 3.37 +/- 0.27 beats center dot min(-1) center dot mmHg(-1), P < 0.05). We conclude that Cort acts in the DHB to increase the midpoint and reduce the gain of the heart rate baroreflex function.