Sprangers S A, West N B, Brenner R M, Bethea C L
Division of Reproductive Biology and Behavior, Oregon Regional Primate Research Center, Beaverton 97006.
Endocrinology. 1990 Feb;126(2):1133-42. doi: 10.1210/endo-126-2-1133.
PRL increases during pregnancy in primates with rising levels of placental estradiol (E) and progesterone (P). However, while E will increase PRL secretion in monkey pituitary cell cultures, P has no effect. We recently localized progestin receptors (PR) to gonadotropes, but not lactotropes, with an immunocytochemical technique to double stain monkey pituitary cell cultures. The following studies were performed to confirm the immunocytochemical localization of PR in intact pituitary tissue and to determine the effect of E and P on the levels of estrogen receptors (ER) and PR in the pituitary. ER and PR levels were determined in the endometrium of the same animals for an internal comparison. Thirteen adult cycling female cynomolgus monkeys were ovariectomized and treated for 28 days with 1) an empty Silastic capsule (Spay), 2) a 2-cm E-filled capsule (E), or 3) a 2-cm E-filled capsule for 14 days plus a 6-cm P-filled capsule implanted for an additional 14 days (E + P). Blood samples were drawn daily for assay of serum E, P, and PRL levels. Serum PRL was not significantly affected by E, but the sequential addition of P significantly increased serum PRL levels over those observed in Spray animals. The anterior pituitary and endometrium were removed for measurement of ER and PR levels by a sucrose gradient shift assay incorporating monoclonal antibodies against ER and PR. Pituitary ER levels did not vary significantly with steroid treatment (158.2 +/- 33.6, 135.5 +/- 24.9, 104.3 +/- 13.4 fmol/mg DNA in Spay, E, and E + P animals, respectively). Pituitary PR levels were undetectable in Spay animals, were induced by E (393.3 +/- 53.4 fmol/mg DNA), and were suppressed to undetectable levels by the addition of P. A portion of the pituitary was frozen for immunocytochemical single staining for ER, PR, PRL, and LH and double staining for PRL + PR and LH + PR. ER staining was observed in many parenchymal cells, but there was no apparent change with steroid treatment. PR staining was absent in the Spay animals; many PR-positive cells were observed in E-treated females, and only a small number of faintly staining cells were detected in the E + P animals. Double staining for PRL + PR and LH + PR revealed PR in gonadotropes, but not lactotropes. In conclusion, PR, but not ER, are regulated by E and P in the monkey pituitary. Importantly, PR is regulated within gonadotropes, but not lactotropes. Therefore, P probably increases PRL secretion through a hypothalamic action.
在灵长类动物中，随着胎盘雌二醇（E）和孕酮（P）水平的升高，催乳素（PRL）在孕期会增加。然而，虽然E会增加猴垂体细胞培养物中PRL的分泌，但P没有影响。我们最近用免疫细胞化学技术对猴垂体细胞培养物进行双重染色，将孕激素受体（PR）定位到促性腺激素细胞，而非催乳激素细胞。进行了以下研究以确认PR在完整垂体组织中的免疫细胞化学定位，并确定E和P对垂体中雌激素受体（ER）和PR水平的影响。为了进行内部比较，测定了同一动物子宫内膜中的ER和PR水平。将13只成年处于发情周期的雌性食蟹猴进行卵巢切除，并分别用以下方法处理28天：1）植入空的硅橡胶胶囊（假手术组）；2）植入一个2厘米长填充E的胶囊（E组）；3）先植入一个2厘米长填充E的胶囊14天，再植入一个6厘米长填充P的胶囊14天（E + P组）。每天采集血样以测定血清E、P和PRL水平。E对血清PRL没有显著影响，但依次添加P后，血清PRL水平比假手术组动物显著升高。切除垂体前叶和子宫内膜，通过结合抗ER和PR单克隆抗体的蔗糖梯度转移试验来测量ER和PR水平。垂体ER水平在不同激素处理组中无显著差异（假手术组、E组和E + P组动物的垂体ER水平分别为158.2 ± 33.6、135.5 ± 24.9、104.3 ± 13.4 fmol/mg DNA）。在假手术组动物中未检测到垂体PR水平，E可诱导其产生（393.3 ± 53.4 fmol/mg DNA），而添加P后可将其抑制到检测不到的水平。将一部分垂体冷冻用于ER、PR、PRL和LH的免疫细胞化学单染色以及PRL + PR和LH + PR的双重染色。在许多实质细胞中观察到ER染色，但激素处理后无明显变化。假手术组动物中未观察到PR染色；在E处理的雌性动物中观察到许多PR阳性细胞，而在E + P组动物中仅检测到少数弱阳性染色细胞。PRL + PR和LH + PR的双重染色显示PR存在于促性腺激素细胞中，而非催乳激素细胞中。总之，在猴垂体中，PR受E和P调节，而ER不受其调节。重要的是，PR在促性腺激素细胞中受调节，而非催乳激素细胞。因此，P可能通过下丘脑作用增加PRL分泌。
