Hasegawa O, Sugihara H, Minami S, Wakabayashi I
Department of Medicine, Nippon Medical School, Tokyo, Japan.
Peptides. 1992 May-Jun;13(3):475-81. doi: 10.1016/0196-9781(92)90077-g.
The role of androgen in the sexual dimorphism in hypothalamic growth hormone (GH)-releasing hormone (GHRH) and somatostatin (SS) gene expression was examined in rats. In the first study, the SS and GHRH mRNA levels were measured in both male and female rats at 4, 6, 8, and 10 weeks of age. A significant sex-related difference in the SS and GHRH mRNA levels was observed after 8 weeks of age, when sexual maturation is fully attained. Male rats had higher SS and GHRH mRNA levels than the female rats. In the second study, adult ovariectomized rats received daily injection of dihydrotestosterone (DHT), nonaromatizable testosterone, at a dose of 2 mg/rat for 21 days. The DHT treatment masculinized the GH secretory pattern, which was indistinguishable from that of intact male rats, and simultaneously augmented the SS and GHRH mRNA levels. The DHT treatment of ovariectomized rats after hypophysectomy significantly raised the level of SS mRNA, but not that of GHRH mRNA compared to the control animals. These findings suggest that the activation of the SS gene expression through androgen receptor plays an important role in the maintenance of sexual dimorphism in GH secretion in rats.
研究了雄激素在大鼠下丘脑生长激素（GH）释放激素（GHRH）和生长抑素（SS）基因表达性二态性中的作用。在第一项研究中，测定了4、6、8和10周龄雄性和雌性大鼠的SS和GHRH mRNA水平。在8周龄时，即性成熟完全达成后，观察到SS和GHRH mRNA水平存在显著的性别相关差异。雄性大鼠的SS和GHRH mRNA水平高于雌性大鼠。在第二项研究中，成年去卵巢大鼠每天接受剂量为2mg/大鼠的双氢睾酮（DHT，不可芳香化的睾酮）注射，持续21天。DHT处理使GH分泌模式雄性化，与完整雄性大鼠的模式无法区分，同时增加了SS和GHRH mRNA水平。与对照动物相比，垂体切除术后对去卵巢大鼠进行DHT处理显著提高了SS mRNA水平，但未提高GHRH mRNA水平。这些发现表明，通过雄激素受体激活SS基因表达在维持大鼠GH分泌的性二态性中起重要作用。
