Millan M A, Aguilera G
Endocrinology Reproduction Research Branch, National Institute of Child Health and Human Development, Bethesda, Maryland 20892.
Endocrinology. 1988 May;122(5):1984-90. doi: 10.1210/endo-122-5-1984.
Receptors for angiotensin II (AII) were identified and characterized in testes of rats and several primate species. Autoradiographic analysis of the binding of 125I-labeled [Sar1,Ile8]AII to rat, rhesus monkey, cebus monkey, and human testicular slide-mounted frozen sections indicated specific binding to Leydig cells in the interstitium. In rat collagenase-dispersed interstitial cells fractionated by Percoll gradient, AII receptor content was parallel to that of hCG receptors, confirming that the AII receptors are in the Leydig cells. In rat dispersed Leydig cells, binding was specific for AII and its analogs and of high affinity (Kd, 4.8 nM), with a receptor concentration of 15 fmol/10(6) cells. Studies of AII receptors in rat testes during development reveals the presence of high receptor density in newborn rats which decreases toward the adult age (4934 +/- 309, 1460 +/- 228, 772 +/- 169, and 82 +/- 12 fmol/mg protein at 5, 15, 20, and 30 days of age, respectively) with no change in affinity. At all ages receptors were located in the interstitium, and the decrease in binding was parallel to the decrease in the interstitial to tubular ratio observed with age. AII receptor properties in membrane-rich fractions from prepuberal testes were similar in the rat and rhesus monkey. Binding was time and temperature dependent, reaching a plateau at 60 min at 37 C, and was increased by divalent cations, EGTA, and dithiothreitol up to 0.5 mM. In membranes from prepuberal monkey testes, AII receptors were specific for AII analogs and of high affinity (Kd, 4.2 nM) with a receptor concentration of 7599 +/- 1342 fmol/mg protein. The presence of AII receptors in Leydig cells in rat and primate testes in conjunction with reports of the presence of other components of the renin-angiotensin system in the testes suggests that the peptide has a physiological role in testicular function.
在大鼠和几种灵长类动物的睾丸中鉴定并表征了血管紧张素 II（AII）受体。用放射性自显影分析 125I 标记的[Sar1，Ile8]AII 与大鼠、恒河猴、僧帽猴和人类睾丸冰冻切片的结合情况，结果表明其与间质中的 Leydig 细胞有特异性结合。在经胶原酶分散并用 Percoll 梯度分离的大鼠间质细胞中，AII 受体含量与 hCG 受体含量平行，证实 AII 受体存在于 Leydig 细胞中。在大鼠分散的 Leydig 细胞中，该结合对 AII 及其类似物具有特异性且亲和力高（解离常数 Kd 为 4.8 nM），受体浓度为 15 fmol/10(6)个细胞。对大鼠睾丸发育过程中 AII 受体的研究表明，新生大鼠中存在高受体密度，随着年龄增长至成年，受体密度逐渐降低（分别在 5、15、20 和 30 日龄时，受体密度为 4934±309、1460±228、772±169 和 82±12 fmol/mg 蛋白），而亲和力无变化。在所有年龄段，受体均位于间质中，结合减少与随年龄观察到的间质与小管比例下降平行。大鼠和恒河猴青春期前睾丸富含膜的部分中的 AII 受体特性相似。结合具有时间和温度依赖性，在 37℃下 60 分钟达到平台期，并且在二价阳离子、EGTA 和高达 0.5 mM 的二硫苏糖醇存在下结合增加。在青春期前猴睾丸的膜中，AII 受体对 AII 类似物具有特异性且亲和力高（Kd 为 4.2 nM），受体浓度为 7599±1342 fmol/mg 蛋白。大鼠和灵长类动物睾丸的 Leydig 细胞中存在 AII 受体，再结合睾丸中存在肾素 - 血管紧张素系统其他成分的报道，表明该肽在睾丸功能中具有生理作用。
