Myatt L, Chaudhuri G, Elder M G, Lim L
Biochem J. 1978 Nov 15;176(2):523-9. doi: 10.1042/bj1760523.
We investigated the binding characteristics, content and intracellular distribution of nuclear and cytosolic oestrogen receptors in the uteri of rats bearing a unilateral intrauterine device, fitted 14--18 days earlier, at four phases of a 5-day oestrous cycle. The patterns of changes in wet weight and content of cytosolic and nuclear receptor that normally occur during the oestrous cycle were not altered by the presence of the device. At all stages of the cycle the intra-uterine-device-containing horn had a greater wet weight and a correspondingly higher content of cytosolic receptor than its contralateral control horn, the cellular concentration of cytosolic receptor being apparently maintained. However, the intra-uterine-device-containing horn had significantly lower cellular concentrations (i.e. per mg of DNA) of nuclear receptor, particularly at late dioestrus and pro-oestrus. Thus the treated horn showed a decreased translocation of receptor in response to increases in circulating oestrogens. Both horns contained equivalent amounts of an activating factor implicated in translocation and measured in vitro by binding of cytosol receptor to oligo(dT)-cellulose. The presence of an intra-uterine device neither altered the dissociation constants (Kd) of the nuclear and cytosolic oestrogen-receptor complexes nor the stability of the nuclear receptor complex in vitro. The decreased translocation cannot thus be directly attributed to changes in the physical properties of the receptor. This decrease may be responsible for the anti-fertility effect of the intra-uterine device (which affects only the treated horn of the bicornuate rat uterus), since implantation of the blastocyst requires correct concentrations of nuclear oestrogen receptor.
我们研究了在5天发情周期的四个阶段，于14 - 18天前放置单侧宫内节育器的大鼠子宫中核雌激素受体和胞质雌激素受体的结合特性、含量及细胞内分布。发情周期中正常发生的子宫湿重以及胞质和核受体含量的变化模式并未因宫内节育器的存在而改变。在周期的所有阶段，含宫内节育器的子宫角比其对侧对照子宫角具有更大的湿重和相应更高的胞质受体含量，胞质受体的细胞浓度显然保持不变。然而，含宫内节育器的子宫角核受体的细胞浓度（即每毫克DNA）显著较低，尤其是在间情期末期和发情前期。因此，处理过的子宫角对循环雌激素增加的反应显示受体易位减少。两个子宫角含有等量的一种与易位有关的激活因子，该因子通过胞质受体与寡聚（dT） - 纤维素的结合在体外进行测定。宫内节育器的存在既未改变核雌激素受体复合物和胞质雌激素受体复合物的解离常数（Kd），也未改变体外核受体复合物的稳定性。因此，易位减少不能直接归因于受体物理性质的变化。这种减少可能是宫内节育器抗生育作用的原因（宫内节育器仅影响双角大鼠子宫的处理侧子宫角），因为胚泡着床需要正确浓度的核雌激素受体。
