Carmignac D F, Robinson I C, Enberg B, Norstedt G
Division of Neurophysiology and Neuropharmacology, National Institute for Medical Research, Mill Hill, London, U.K.
J Endocrinol. 1993 Aug;138(2):267-74. doi: 10.1677/joe.0.1380267.
In the rat, many actions of GH depend upon the sexually dimorphic pattern of exposure to GH. Hepatic human GH (hGH) receptor binding differs between the sexes and is sensitive to GH deficiency, but this has mostly been studied in acutely hypophysectomized rats, which lack all pituitary hormones. We have used a strain of GH-deficient dwarf (Dw) rats to determine whether chronic GH deficiency alters the normal developmental pattern and sexually dimorphic expression of hepatic GH receptors. Adult female Dw rats had lower levels of 125I-labelled hGH binding (reflecting predominantly lactogenic receptors) than their normal counterparts whereas there was no difference between adult Dw and normal males; binding capacity increased from 25 days of age, becoming sexually dimorphic from 40 days to adulthood in both strains (% specific binding/mg protein: normal males 1.6 +/- 0.3, normal females 13.2 +/- 1.1, Dw males 2.1 +/- 0.4, Dw females 10.0 +/- 0.6). In contrast, hepatic 125I-labelled bovine GH (bGH) binding (somatogenic receptors) was much lower, and similar in both Dw and normal animals. A sex difference in 125I-labelled bGH binding was only seen in adult animals, and was considerably less marked in Dw rats compared with normal animals (normal males 1.3 +/- 0.1, normal females 2.5 +/- 0.2, Dw males 1.9 +/- 0.2, Dw females 2.4 +/- 0.2%/mg protein). Continuous hGH infusion stimulated growth in female Dw rats, and raised somatogenic and lactogenic GH binding (3.2 +/- 0.4 and 19.6 +/- 2.5%/mg protein) compared with sham-infused controls (2.4 +/- 0.2 and 7.9 +/- 0.6%/mg protein).(ABSTRACT TRUNCATED AT 250 WORDS)
在大鼠中，生长激素（GH）的许多作用取决于接触GH的性别二态性模式。肝脏中人GH（hGH）受体的结合在两性之间存在差异，并且对GH缺乏敏感，但这大多是在急性垂体切除的大鼠中进行研究的，这些大鼠缺乏所有垂体激素。我们使用了一种GH缺乏的侏儒（Dw）大鼠品系来确定慢性GH缺乏是否会改变肝脏GH受体的正常发育模式和性别二态性表达。成年雌性Dw大鼠的125I标记的hGH结合水平（主要反映催乳素受体）低于正常雌性大鼠，而成年Dw大鼠和正常雄性大鼠之间没有差异；结合能力从25日龄开始增加，在两个品系中从40日龄到成年期都表现出性别二态性（特异性结合/%蛋白质：正常雄性1.6±0.3，正常雌性13.2±1.1，Dw雄性2.1±0.4，Dw雌性10.0±0.6）。相比之下，肝脏中125I标记的牛GH（bGH）结合（促生长受体）要低得多，并且在Dw大鼠和正常动物中相似。125I标记的bGH结合的性别差异仅在成年动物中可见，与正常动物相比，Dw大鼠中的差异明显较小（正常雄性1.3±0.1，正常雌性2.5±0.2，Dw雄性1.9±0.2，Dw雌性2.4±0.2%/mg蛋白质）。持续输注hGH刺激了雌性Dw大鼠的生长，并提高了促生长和催乳素GH结合水平（3.2±0.4和19.6±2.5%/mg蛋白质），而假输注对照组为（2.4±0.2和7.9±0.6%/mg蛋白质）。（摘要截短于250字）
