Hirai K, Song K, Kanehara H, Shiota N, Ueda H, Kim S, Miyazaki H, Katsuoka Y, Miyazaki M
Department of Urology, Osaka Medical College, Japan.
Int J Androl. 1998 Aug;21(4):177-85. doi: 10.1046/j.1365-2605.1998.00102.x.
Angiotensin II (AT2) has been implicated in the growth and/or differentiation of its target tissues. In the present study, testicular AT2 receptor and its subtypes in hypophysectomized rats were examined using quantitative in vitro autoradiography and Northern blot analysis in an attempt to determine possible involvement of pituitary hormones in their expression. Prepubescent (3 weeks of age) male Sprague-Dawley rats underwent hypophysectomy or sham operation. From 10 days thereafter, they were treated with vehicle, growth hormone, human chorionic gonadotrophin or human menopausal gonadotrophin for 10 days. Testicular AT2 receptors were labelled with 125I-[Sar1,Ile8] AT2 and differentiated into its subtypes (AT1 and FAT2) according to their susceptibility to AT1 (losartan, 5 microM) and AT2 (CGP42112B, 1 microM) antagonists. Hypophysectomy led to a marked increase in AT2 receptor concentration (sham-operated rats: 0.7 +/- 0.2 fmol/mg protein, hypophysectomized rats: 2.5 +/- 0.6 fmol/mg protein, mean +/- SEM, n = 11-12, p < 0.01) with predominant occurrence of AT1 receptors. Both human chorionic gonadotrophin and human menopausal gonadotrophin decreased testicular AT2 receptor concentration, whereas growth hormone did not affect AT2 receptor expression. Northern blot analysis revealed both testicular AT1 and AT2 receptor mRNA expression to be significantly increased after hypophysectomy and reduced by gonadotrophin treatment. These results suggest that the expression of testicular AT2 receptors is regulated by pituitary gonadotrophins and that AT2 may play a role in testicular growth and/or differentiation.
血管紧张素 II（AT2）与其靶组织的生长和/或分化有关。在本研究中，使用定量体外放射自显影和 Northern 印迹分析检测了垂体切除大鼠睾丸中的 AT2 受体及其亚型，以确定垂体激素是否可能参与其表达。青春期前（3 周龄）雄性 Sprague-Dawley 大鼠接受垂体切除或假手术。此后 10 天，它们接受载体、生长激素、人绒毛膜促性腺激素或人绝经后促性腺激素治疗 10 天。睾丸 AT2 受体用 125I-[Sar1，Ile8]AT2 标记，并根据它们对 AT1（氯沙坦，5μM）和 AT2（CGP42112B，1μM）拮抗剂的敏感性分为其亚型（AT1 和 FAT2）。垂体切除导致 AT2 受体浓度显著增加（假手术大鼠：0.7±0.2 fmol/mg 蛋白，垂体切除大鼠：2.5±0.6 fmol/mg 蛋白，平均值±SEM，n = 11 - 12，p < 0.01），主要为 AT1 受体。人绒毛膜促性腺激素和人绝经后促性腺激素均降低了睾丸 AT2 受体浓度，而生长激素不影响 AT2 受体表达。Northern 印迹分析显示，垂体切除后睾丸 AT1 和 AT2 受体 mRNA 表达均显著增加，而促性腺激素治疗使其降低。这些结果表明，睾丸 AT2 受体的表达受垂体促性腺激素调节，并且 AT2 可能在睾丸生长和/或分化中起作用。
