Koskinen L O
Br J Pharmacol. 1986 Mar;87(3):509-19. doi: 10.1111/j.1476-5381.1986.tb10193.x.
Local cerebral and peripheral blood flow in conscious and anaesthetized rabbits were investigated with the microsphere method, before and after the i.v. administration of 25 or 50 micrograms kg-1 thyrotropin-releasing hormone (TRH). Before the experiment, the cervical sympathetic chain was sectioned on one side in order to evaluate the possible effect of the sympathetic nerves on cranial and extracranial blood flows. Blood flow was also determined in anaesthetized rabbits before and after the administration of the TRH metabolites cyclo(His-Pro) and acid-TRH and after subsequent administration of 50 micrograms kg-1 TRH. TRH caused an increase in mean arterial blood pressure (MAP) of about 1 to 2 kPa whereas cyclo(His-Pro) and acid-TRH had no effect on MAP. In the anaesthetized animal an increase in total cerebral blood flow (CBFtot), from 71 +/- 7 to 107 +/- 12 g min-1 100 g-1 (P less than 0.05) was observed on the sympathetic intact side after 25 micrograms kg-1 TRH and a further increase to 130 +/- 9 g min-1 100g-1 (P less than 0.01) after 50 micrograms kg-1 TRH. A similar effect was observed on the sympathotomized side. An effect on CBF in the conscious animal was not detected. The control CBFtot (104 +/- 8 g min-1 100g-1) was higher in these animals than in the anaesthetized animals (P less than 0.02). Neither cyclo(His-Pro) nor acid-TRH mimicked the effect of TRH on CBF. In several peripheral tissues, e.g. skin, pancreas and gastric mucosa, a reduction in blood flow was noted after the administration of TRH in both anaesthetized and conscious rabbits. It was concluded that TRH can induce cerebral vasodilatation in animals with a depressed CBF, whereas the vasoconstrictor effect of TRH in peripheral organs is not markedly affected by the state of consciousness.
采用微球法，在静脉注射25或50微克/千克促甲状腺激素释放激素（TRH）前后，对清醒和麻醉兔的局部脑血流及外周血流进行了研究。实验前，切断一侧颈交感神经链，以评估交感神经对颅内外血流的可能影响。还测定了麻醉兔在注射TRH代谢产物环（组氨酸-脯氨酸）和酸性TRH前后以及随后注射50微克/千克TRH后的血流情况。TRH使平均动脉血压（MAP）升高约1至2千帕，而环（组氨酸-脯氨酸）和酸性TRH对MAP无影响。在麻醉动物中，静脉注射25微克/千克TRH后，交感神经完整侧的总脑血流量（CBFtot）从71±7增加到107±12克/分钟·100克-1（P<0.05），注射50微克/千克TRH后进一步增加到130±9克/分钟·100克-1（P<0.01）。在交感神经切断侧也观察到类似效应。未检测到TRH对清醒动物脑血流量的影响。这些动物的对照CBFtot（104±8克/分钟·100克-1）高于麻醉动物（P<0.02）。环（组氨酸-脯氨酸）和酸性TRH均未模拟TRH对脑血流量的影响。在几种外周组织，如皮肤、胰腺和胃黏膜中，麻醉和清醒兔注射TRH后均出现血流减少。得出结论：TRH可诱导脑血流量降低的动物脑血管扩张，而TRH在外周器官的血管收缩作用不受意识状态的明显影响。
