1,25-dihydroxyvitamin D3 receptors in the seminiferous tubules of the rat testis increase at puberty.
1,25-dihydroxyvitamin D3 receptors in the seminiferous tubules of the rat testis increase at puberty.
复制标题
DOI：
10.1210/endo-114-6-2167
复制
发表时间：
1984-06
期刊：
影响因子：
4.8
通讯作者：
M. Walters
中科院分区：
文献类型：
--
作者：
M. Walters
研究了1，25-二羟维生素D3 [1，25-（OH）2D 3]受体水平是否与青春期前大鼠睾丸的体内快速生长速率相关。低盐染色质定位的1，25-（OH）2D 3受体进行了比较，在睾丸和肠粘膜（对照）的青春期前，青春期前后，和成熟大鼠（37，49，和90日龄，分别）。与青春期前后和成熟组相比，青春期前大鼠睾丸中每克湿重1，25-（OH）2D 3受体的数量显着减少（P <0.02）。相反，在这些年龄组中，在对照组织肠粘膜中未观察到1，25-（OH）2D 3受体水平的变化。进一步的实验证实了睾丸1，25-（OH）2D 3受体的身份。特异性[3 H] 1，25-（OH）2D 3结合组分主要位于低渗缓冲液中的细胞核/染色质部分。[3 H] 1，25-（OH）2D 3与成年大鼠睾丸染色质结合的Scatchard分析产生单一特异性结合组分，Kd为0.33 +/- 0.06 nM，Nmax为102.3 +/- 6.4 fmol/g组织（n = 6），过量的1，25-（OH）2D 3可抑制该结合组分，但50 nM 25-羟基维生素D3仅能最小程度地抑制该结合组分。蔗糖梯度分析需要羟基磷灰石处理离心后的馏分，以除去游离的3 H-标记的类固醇。通过这种修饰，[3 H] 1，25-（OH）2D 3的离散3.6S峰被揭开，其被过量的1，25-（OH）2D 3消除，但不被50 nM 25-羟基维生素D3或1 μ M皮质醇或孕酮类似物普洛孕酮消除。尽管1，25-（OH）2D 3受体似乎无处不在，但它确实表现出组织特异性，因为它似乎在前列腺中不存在，充其量在附睾中大大减少。通过机械分离间质细胞（占总[125 I]hCG结合的93.7%）与小管，检查睾丸1，25-（OH）2D 3受体的细胞定位。在这些条件下，91.3%的特异性[3 H] 1，25-（OH）2D 3结合发生在管状染色质制备物中。因此，这些数据提供了证据，在大鼠睾丸曲细精管中存在特异性1，25-（OH）2D 3受体。此外，增加的1，25-（OH）2D 3受体水平与睾丸成熟的时间相关性表明，睾丸功能和精子发生的相关性比体内器官的生长更好。
Whether 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] receptor levels correlate with the rapid in vivo growth rate of the testes in the prepubertal rat was examined. Low salt chromatin-localized 1,25-(OH)2D3 receptors were compared in the testes and intestinal mucosa (control) of prepubertal, peripubertal, and mature rats (37, 49, and 90 days old, respectively). The number of 1,25-(OH)2D3 receptors per g wet wt was significantly (P less than 0.02) reduced in the testes of the prepubertal rats compared to those in the peripubertal and mature groups. Conversely, no changes were observed in the 1,25-(OH)2D3 receptor levels in the control tissue intestinal mucosa among these age groups. Further experiments confirmed the identity of the testicular 1,25-(OH)2D3 receptors. The specific [3H]1,25-(OH)2D3-binding component was predominantly localized in the nuclei/chromatin fraction in hypotonic buffers. Scatchard analysis of [3H]1,25-(OH)2D3 binding to the testicular chromatin of adult rats yielded a single specific binding component with a Kd of 0.33 +/- 0.06 nM and a Nmax of 102.3 +/- 6.4 fmol/g tissue (n = 6), which was inhibited by excess 1,25-(OH)2D3, but only minimally by 50 nM 25-hydroxyvitamin D3. Sucrose gradient analysis required hydroxylapatite treatment of fractions after centrifugation to remove free 3H-labeled steroid. With this modification, a discrete 3.6S peak of [3H]1,25-(OH)2D3 was unmasked, which was eliminated by excess 1,25-(OH)2D3, but not by 50 nM 25-hydroxyvitamin D3, or 1 microM cortisol, or the progesterone analog promegestone. In spite of its seemingly ubiquitous distribution, the 1,25-(OH)2D3 receptor does exhibit tissue specificity, since it appears to be absent in the prostate and, at best, greatly reduced in the epididymis. The cellular localization of the testicular 1,25-(OH)2D3 receptors was examined by mechanically separating interstitial cells (93.7% of the total [125I]hCG binding) from the tubules. Under these conditions, 91.3% of the specific [3H]1,25-(OH)2D3 binding occurred in the tubular chromatin preparation. Thus, these data provide evidence for the presence of a specific 1,25-(OH)2D3 receptor in the seminiferous tubules of the rat testis. Moreover, the temporal correlation of increased 1,25-(OH)2D3 receptor levels with testicular maturation suggests a better correlation to testicular function and spermatogenesis than to growth of the organ in vivo.