Hanlin M L, Yount A P
Endocr Res Commun. 1975;2(8):489-502. doi: 10.3109/07435807509050673.
Prolactin binding sites have been reported in a variety of tissues that are hormonally responsive to prolactin (PRL). A synergistic effect of PRL and androgens upon the secondary sexual structures of the male rat has been demonstrated. The present study was designed to: 1) determine if there are PRL binding sites in a membrane-rich particulate fraction of the rat ventral prostate: and 2) study the effect of changing the hormonal environment upon this specific PRL binding. The binding of lactoperoxidase iodinated ovine prolactin (I125-PRL) to rat prostatic membrane preparations was assayed by the method of Shiu and Friesen. Serum LH and PRL were measured by radioimmunoassay. The specific binding of I125-PRL that was observed in the prostatic membrane preparation of intact adult male rats was readily displaced by excess unlabelled ovine or rat PRL but not by rat LH or FSH. This binding was decreased by heating or trypsin treatment of the membrane preparation. Tissue specificity was demonstrated in that no specific binding was observed in membrane preparations of lung or spleen from these male rats. Prostatic membrane preparations from adult rats that were castrated for either 4 or 8 days showed a 90% decrease in specific I125-PRL binding while serum PRL values were not changed. Daily subcutaneous administration of testosterone propionate (2.0 mg/rat) to 4-day castrated adult rats resulted in I125-PRL binding comparable to that of intact rats. The data show that a reduction of endogenous androgens results in diminished I125-PRL binding in the ventral prostate of the rat.
在多种对催乳素（PRL）产生激素反应的组织中都已报道存在催乳素结合位点。已证实催乳素和雄激素对雄性大鼠的第二性征具有协同作用。本研究旨在：1）确定大鼠腹侧前列腺富含膜的颗粒部分中是否存在催乳素结合位点；2）研究改变激素环境对这种特定催乳素结合的影响。采用Shiu和Friesen的方法测定了乳过氧化物酶碘化的绵羊催乳素（I125-PRL）与大鼠前列腺膜制剂的结合。通过放射免疫测定法测量血清促黄体生成素（LH）和催乳素。在完整成年雄性大鼠的前列腺膜制剂中观察到的I125-PRL特异性结合很容易被过量的未标记绵羊或大鼠催乳素取代，但不会被大鼠LH或促卵泡生成素（FSH）取代。这种结合通过对膜制剂进行加热或胰蛋白酶处理而减少。通过对这些雄性大鼠的肺或脾膜制剂未观察到特异性结合，证明了组织特异性。切除睾丸4天或8天的成年大鼠的前列腺膜制剂显示特异性I125-PRL结合减少了90%，而血清催乳素值未改变。对切除睾丸4天的成年大鼠每日皮下注射丙酸睾酮（2.0毫克/只大鼠），导致I125-PRL结合与完整大鼠相当。数据表明，内源性雄激素的减少导致大鼠腹侧前列腺中I125-PRL结合减少。
