Sanvitto G L, Jöhren O, Häuser W, Saavedra J M
Section on Pharmacology, National Institute of Mental Health, Bethesda, Maryland 20892, USA.
Am J Physiol. 1997 Jul;273(1 Pt 1):E156-63. doi: 10.1152/ajpendo.1997.273.1.E156.
We studied angiotensin II (ANG II) receptor subtype expression in selected brain nuclei and pituitary gland after water deprivation by in vitro receptor autoradiography using 125I-labeled [Sar1]ANG II and by in situ hybridization using 35S-labeled AT1A, AT1B, and AT2 receptor-specific riboprobes. In control rats we found binding to AT1 receptors in the subfornical organ, paraventricular nucleus, median eminence, and anterior pituitary; AT1A mRNA expression in the subfornical organ and paraventricular nucleus; and AT1B mRNA expression in the anterior pituitary. No receptor mRNA was found in the median eminence. AT1 receptors and AT1A receptor mRNA levels were increased in the subfornical organ, and, in the anterior pituitary, AT1 receptors and AT1B receptor mRNA were increased, only after 5 days of water deprivation. No significant changes occurred after 1 or 3 days of water deprivation, and no regulation of ANG II receptor expression was detected in other brain areas. Our results show that prolonged water deprivation selectively regulates AT1 receptor expression and AT1A and AT1B receptor mRNA levels in the subfornical organ and anterior pituitary, respectively, supporting a role for these receptors during sustained dehydration.
我们通过使用125I标记的[Sar1]血管紧张素II进行体外受体放射自显影，以及使用35S标记的AT1A、AT1B和AT2受体特异性核糖探针进行原位杂交，研究了缺水后特定脑核团和垂体中血管紧张素II（ANG II）受体亚型的表达。在对照大鼠中，我们发现穹窿下器、室旁核、正中隆起和垂体前叶存在与AT1受体的结合；穹窿下器和室旁核中有AT1A mRNA表达；垂体前叶中有AT1B mRNA表达。在正中隆起未发现受体mRNA。仅在缺水5天后，穹窿下器中的AT1受体和AT1A受体mRNA水平升高，垂体前叶中的AT1受体和AT1B受体mRNA升高。缺水1天或3天后未发生显著变化，在其他脑区未检测到ANG II受体表达的调节。我们的结果表明，长期缺水分别选择性地调节穹窿下器和垂体前叶中AT1受体的表达以及AT1A和AT1B受体mRNA水平，支持这些受体在持续脱水过程中的作用。
