Selcer K W, Leavitt W W
Department of Biochemistry, Texas Tech University Health Sciences Center, Lubbock 79430.
Gen Comp Endocrinol. 1988 Dec;72(3):443-52. doi: 10.1016/0016-6480(88)90167-0.
Progesterone is known to selectively down-regulate nuclear estrogen receptor (Re) in the mammalian uterus, and this process is functionally related to embryo retention. It is unclear if this mechanism is operative in the chick oviduct, where egg retention does not occur. We investigated the regulation of Re by progesterone in a mammalian model (proestrous hamster uterus) and an avian model (DES-primed chick oviduct), under the same assay conditions, in an effort to compare progesterone action in viviparous and oviparous species. Nuclear and cytosol estrogen receptor were measured with an assay employing pyridoxal 5'-phosphate (PLP). The PLP assay has the advantage of allowing exchange at low temperature, which results in improved receptor recovery, especially from the nuclear fraction. Parallel studies were done under two different hormonal settings, estrogen primed and estrogen + progesterone primed. Experiments were: (1) response of Re to acute progesterone treatment (5 mg progesterone, 4 hr) in estrogen-primed preparation, (2) time course of the Re down-regulation response (4, 8, and 12 hr after progesterone treatment), and (3) recovery of Re after progesterone withdrawal in estrogen + progesterone-primed preparation. Chick oviduct contained little cytosol Re (0.96 +/- 0.32 pmol/g tissue) compared to hamster uterus (4.27 +/- 0.15 pmol/g tissue), and progesterone treatment had no effect on cytosol Re levels in either species. Nuclear Re levels were similar for chick oviduct (2.68 +/- 0.14 pmol/g tissue) and hamster uterus (2.64 +/- 0.14 pmol/g tissue). Progesterone treatment reduced nuclear Re levels in both the hamster uterus and chick oviduct to about 50% of control levels. In the chick oviduct, down-regulation was transient, as evidenced by complete recovery of nuclear Re to control levels by 12 hr after progesterone administration. In the estrogen + progesterone-primed chick oviduct, nuclear Re increased within 6 hr after progesterone withdrawal and approached maximal levels by 12 hr. These data indicate that progesterone rapidly and selectively down-regulates the nuclear form of Re in the chick oviduct as in the hamster uterus. Thus, the regulation of Re by progesterone appears to be similar in the mammalian uterus and the chick oviduct, despite the basic differences in reproductive strategy between birds and mammals.(ABSTRACT TRUNCATED AT 400 WORDS)
已知孕酮可选择性下调哺乳动物子宫中的核雌激素受体（Re），这一过程在功能上与胚胎着床有关。目前尚不清楚该机制在鸡输卵管中是否起作用，因为鸡输卵管中不会发生卵的滞留。我们在相同的检测条件下，研究了孕酮对哺乳动物模型（动情前期仓鼠子宫）和禽类模型（己烯雌酚预处理的鸡输卵管）中Re的调节作用，以比较孕酮在胎生和卵生动物中的作用。使用5'-磷酸吡哆醛（PLP）检测法测定核雌激素受体和胞质雌激素受体。PLP检测法的优点是允许在低温下进行交换，从而提高受体回收率，特别是从核部分中回收。在两种不同的激素环境下进行了平行研究，即雌激素预处理和雌激素+孕酮预处理。实验包括：（1）在雌激素预处理的制剂中，Re对急性孕酮处理（5mg孕酮，4小时）的反应；（2）Re下调反应的时间进程（孕酮处理后4、8和12小时）；（3）在雌激素+孕酮预处理的制剂中，孕酮撤药后Re的恢复情况。与仓鼠子宫（4.27±0.15pmol/g组织）相比，鸡输卵管中的胞质Re含量很少（0.96±0.32pmol/g组织），孕酮处理对两种动物的胞质Re水平均无影响。鸡输卵管（2.68±0.14pmol/g组织）和仓鼠子宫（2.64±0.14pmol/g组织）的核Re水平相似。孕酮处理使仓鼠子宫和鸡输卵管中的核Re水平均降至对照水平的约50%。在鸡输卵管中，下调是短暂的，孕酮给药后12小时核Re完全恢复到对照水平即可证明。在雌激素+孕酮预处理的鸡输卵管中，孕酮撤药后6小时内核Re增加，12小时时接近最大水平。这些数据表明，与仓鼠子宫一样，孕酮能迅速且选择性地下调鸡输卵管中Re的核形式。因此，尽管鸟类和哺乳动物在生殖策略上存在根本差异，但孕酮对Re的调节在哺乳动物子宫和鸡输卵管中似乎是相似的。（摘要截选至400字）
