Yan J, Chen H, Liao W, Lu S
Research Institute of Surgery, Third Military Medical College, Chongqing, PR China.
Circ Shock. 1992 Jul;37(3):253-61.
To ascertain the central mechanism of the effects of thyrotropin-releasing hormone (TRH) on the cardiovascular system, we evaluated the effects of this neuropeptide on unit fires in the rostral ventro-lateral medulla (RVL), mean arterial pressure (MAP), and heart rate (HR) in normotensive and hypotensive rats. Intracerebroventricular injection (i.c.v.) of 10 micrograms TRH significantly increased MAP and HR in both normotensive and hypotensive rats. No similar effects were observed after saline injection. If electrolytic lesions of bilateral RVL were made, the cardiovascular effects of TRH i.c.v. failed to occur. TRH i.c.v. markedly increased the firing frequency of most units in the RVL. In particular, TRH i.c.v. increased the firing frequency of most units excitatory to a fall in MAP and decreased the firing frequency of most units inhibitory to a fall in MAP in normotensive rats. Moreover, a drop of MAP as low as 40 mmHg for 10 min resulted in an increase of the firing frequency of most units. The effect of TRH i.c.v. on the RVL units in the hypotensive rats was similar to that in the normotensive rats. Our findings suggest that TRH is able to intensify the cardiovascular activities and the RVL plays a key role in the effects of TRH on the cardiovascular system in both normotensive and hypotensive rats.
为了确定促甲状腺激素释放激素（TRH）对心血管系统作用的中枢机制，我们评估了这种神经肽对正常血压和低血压大鼠延髓头端腹外侧区（RVL）单位放电、平均动脉压（MAP）和心率（HR）的影响。向脑室内注射（i.c.v.）10微克TRH可使正常血压和低血压大鼠的MAP和HR显著升高。注射生理盐水后未观察到类似效应。如果对双侧RVL进行电解损伤，TRH脑室内注射的心血管效应则不会出现。TRH脑室内注射显著增加了RVL中大多数单位的放电频率。特别是，TRH脑室内注射增加了正常血压大鼠中大多数对MAP下降起兴奋作用的单位的放电频率，并降低了大多数对MAP下降起抑制作用的单位的放电频率。此外，MAP下降至40 mmHg并持续10分钟会导致大多数单位的放电频率增加。TRH脑室内注射对低血压大鼠RVL单位的作用与正常血压大鼠相似。我们的研究结果表明，TRH能够增强心血管活动，并且RVL在TRH对正常血压和低血压大鼠心血管系统的作用中起关键作用。
