Glaser L A, Kelly P A, Gibori G
Endocrinology. 1984 Sep;115(3):969-76. doi: 10.1210/endo-115-3-969.
The abilities of the two different mol wt forms of rat placental lactogen (rPL) to maintain luteal steroidogenesis in pregnant rats in the absence of PRL were determined. The two forms of rPL present in day 12 pregnant rat serum were separated by gel chromatography, lyophilized, and reconstituted in a volume of saline equal to the original volume of serum. Rats were injected with 0.4 mg ergocryptine (ECO) on day 6 of pregnancy to suppress PRL and were then treated with a preparation of the large mol wt (LMW) hormone, the small mol wt (SMW) hormone, or both molecules (2 ml/day). Control animals received saline. Twice daily injections of the amount of LMW hormone contained in 1 ml day 12 pregnant rat serum reversed the abortifacient effect of ECO. In contrast, administration of the SMW hormone did not maintain either pregnancy or progesterone levels. Administration of both mol wt forms of rPL was also capable of maintaining luteal function. Sera obtained from day 18 pregnant rats containing only the SMW hormone had no luteotropic activity when administered, yet treatment with sera of day 12 pregnant rats sustained progesterone synthesis and fetal survival after ECO treatment. rPL were measured in the peripheral circulation and in the uterine vein throughout pregnancy by radioreceptor assay (RRA) using particulate membranes from either rabbit mammary gland or rat ovaries. Two peaks of activity were observed in the peripheral circulation by the two RRAs: one between days 11-14 and another between days 17-21, with a decline in activity between days 14-16. In contrast, levels of rPL in the uterine vein remained elevated throughout pregnancy. Concentrations of the LMW placental luteotropin were 5-10 times higher by ovarian RRA (O-RRA) than by mammary gland RRA (MG-RRA) between days 11-13, but concentrations of the SMW placental lactogen were found by the two RRAs to be similar in the later stages of pregnancy. Gel filtration of day 12 pregnant rat serum revealed two peaks of PRL-like activity. The O-RRA detected 19 times more LMW placental luteotropin than did the MG-RRA in the first peak of activity, yet measured equivalent amounts of the SMW placental lactogen in the second peak. Similar to results found in the peripheral circulation, levels of LMW placental luetotropin in the uterine vein measured by MG-RRA were significantly lower than those determined by O-RRA until day 14 of pregnancy.(ABSTRACT TRUNCATED AT 400 WORDS)
测定了大鼠胎盘催乳素（rPL）两种不同分子量形式在无催乳素（PRL）情况下维持妊娠大鼠黄体类固醇生成的能力。通过凝胶色谱法分离妊娠第12天大鼠血清中存在的两种形式的rPL，冻干后用与原始血清体积相等的生理盐水复溶。在妊娠第6天给大鼠注射0.4mg麦角隐亭（ECO）以抑制PRL，然后用大分子（LMW）激素制剂、小分子（SMW）激素制剂或两种分子（2ml/天）进行处理。对照动物注射生理盐水。每天两次注射1ml妊娠第12天大鼠血清中所含的LMW激素量可逆转ECO的流产效应。相比之下，给予SMW激素既不能维持妊娠也不能维持孕酮水平。给予两种分子量形式的rPL也能够维持黄体功能。从妊娠第18天大鼠获得的仅含SMW激素的血清在给药时没有促黄体活性，但用妊娠第12天大鼠血清处理可在ECO处理后维持孕酮合成和胎儿存活。在整个妊娠期间，通过使用来自兔乳腺或大鼠卵巢的颗粒膜的放射受体测定法（RRA）在外周循环和子宫静脉中测量rPL。两种RRA在外周循环中观察到两个活性峰值：一个在第11 - 14天之间，另一个在第17 - 21天之间，在第14 - 16天之间活性下降。相比之下，子宫静脉中rPL水平在整个妊娠期间保持升高。在第11 - 13天之间，通过卵巢RRA（O - RRA）测定的LMW胎盘促黄体素浓度比通过乳腺RRA（MG - RRA）高5 - 10倍，但在妊娠后期，两种RRA发现SMW胎盘催乳素浓度相似。对妊娠第12天大鼠血清进行凝胶过滤显示出两个催乳素样活性峰。在第一个活性峰中，O - RRA检测到的LMW胎盘促黄体素比MG - RRA多19倍，但在第二个峰中测量到的SMW胎盘催乳素量相当。与在外周循环中发现的结果相似，直到妊娠第14天，通过MG - RRA测量的子宫静脉中LMW胎盘促黄体素水平明显低于通过O - RRA测定的水平。（摘要截短至400字）
