Kanehara H, Song K, Hirai K, Ueda H, Shiota N, Azuma H, Katsuoka Y, Miyazaki H, Miyazaki M
Department of Urology, Osaka Medical College, Japan.
Int J Androl. 1998 Aug;21(4):186-95.
Expression of testicular angiotensin II (AT2) receptors in Sprague-Dawley rats at various stages of development (1 and 5 days, 2, 3, 4 and 7 weeks postnatal) were studied by in vitro autoradiography and Northern blot analysis. The receptors were labelled with 125I-[Sar1, Ile8]AT2 and differentiated into two subtypes according to their susceptibility to AT1 (losartan, 5 microM) or AT2 (PD123319, 5 microM) antagonist. Total AT2 receptor binding in the testis was highest at 1 day of age (8.12 +/- 0.35 fmol/mg protein, mean +/- secEM, n = 8) and decreased gradually thereafter (5 days: 6.9 +/- 0.41, 2 weeks: 2.85 +/- 0.10, 3 weeks: 1.64 +/- 0.19, 4 weeks: 0.76 +/- 0.09, 6 weeks: 0.77 +/- 0.09 fmol/mg protein, n = 8-11). AT2 receptor binding was strikingly abundant in 1-day-old rat testis (6.98 +/- 0.34 fmol/mg protein), while considerably less AT1 receptor binding (1.46 +/- 0.19 fmol/mg protein) was observed. The relative amounts of each subtype did not change for the first 3 weeks but the 4-week-old rat testis contained almost exclusively AT1 receptors (0.63 +/- 0.05 fmol/mg protein). Northern blot analysis showed that mRNA expression of both AT1 and AT2 types decreased with age. Microscopic emulsion autoradiography was undertaken to clarify the localization of binding. At 10 days of age, both AT1 and AT2 receptors were present in the interstitial area, whereas seminiferous tubules contained mainly AT2 receptors. At 7 weeks of age, no significant binding was observed in the seminiferous tubule and the interstitial area contained AT1 receptors exclusively. These results demonstrate expression of AT2 receptors in the rapidly growing testis and suggest that change in the levels of AT2 receptor subtypes may be relevant to development and/or growth of the testis.
通过体外放射自显影和Northern印迹分析，研究了不同发育阶段（出生后1天和5天、2、3、4和7周）的Sprague-Dawley大鼠睾丸血管紧张素II（AT2）受体的表达。用125I-[Sar1，Ile8]AT2标记受体，并根据它们对AT1（氯沙坦，5微摩尔）或AT2（PD123319，5微摩尔）拮抗剂的敏感性分为两种亚型。睾丸中总AT2受体结合在出生后1天时最高（8.12±0.35飞摩尔/毫克蛋白质，平均值±标准误，n = 8），此后逐渐下降（5天：6.9±0.41，2周：2.85±0.10，3周：1.64±0.19，4周：0.76±0.09，6周：0.77±0.09飞摩尔/毫克蛋白质，n = 8 - 11）。AT2受体结合在1日龄大鼠睾丸中极为丰富（6.98±0.34飞摩尔/毫克蛋白质），而观察到的AT1受体结合量则少得多（1.46±0.19飞摩尔/毫克蛋白质）。在最初3周内，每种亚型的相对量没有变化，但4周龄大鼠睾丸几乎只含有AT1受体（0.63±0.05飞摩尔/毫克蛋白质）。Northern印迹分析表明，AT1和AT2两种类型的mRNA表达均随年龄下降。进行了显微乳胶放射自显影以阐明结合的定位。在10日龄时，AT1和AT2受体均存在于间质区域，而曲细精管主要含有AT2受体。在7周龄时，曲细精管中未观察到明显的结合，间质区域仅含有AT1受体。这些结果证明了AT2受体在快速生长的睾丸中的表达，并表明AT2受体亚型水平的变化可能与睾丸的发育和/或生长有关。
