Mick C C, Nicoll C S
Endocrinology. 1985 May;116(5):2049-53. doi: 10.1210/endo-116-5-2049.
Recent studies in our laboratory indicated that the liver of rats, mice, and pigeons secretes a PRL-synergizing activity (synlactin) in vitro. Accordingly, we investigated whether PRL and/or GH could stimulate the secretion of synlactin by the pigeon liver or kidney. Young birds received twice daily injections of PBS, ovine (o) PRL, or oGH for 5 days. On the sixth day, their livers and kidneys were removed, and slices of these organs were incubated in medium 199 for 4 h. The medium samples were filtered and diluted, then tested for PRL-like activity and synlactin activity in the local pigeon crop-sac bioassay. The latter test involved adding a dose of 1.0 microgram oPRL to the medium samples. None of the liver or kidney medium samples had PRL-like activity when tested alone. Only the liver incubation medium from the PRL-injected pigeons contained significant amounts of synlactin activity. Our next experiment was designed to determine whether PRL stimulation of hepatic secretion of synlactin involved a direct action of the hormone on the liver in vivo. A catheter attached to a coil of tubing and an osmotic minipump was inserted into an intestinal vein of pigeons, and the pump and coil were left in the abdomen. By this means, solvent, or GH or PRL in solvent, was pulse infused (four pulses of 2 h each per day) into the intestinal venous drainage. Thus, the hormones were delivered directly to the liver via the hepatic portal vein. During the last 3 of the 7 days of infusion, the pigeons received two daily injections of PBS or oPRL over the contralateral lobes of the crop-sac. Intrahepatic infusion of PRL, but not GH, caused a marked augmentation of the response of the crop to local injections of PRL. Pulse infusion of the same dose of oPRL into the external jugular vein of pigeons did not have this effect; hence, it appears to be mediated by the liver. These results indicate that one of the actions of PRL on the liver is to stimulate the secretion of a factor (synlactin) which acts synergistically with the hormone to promote growth of its target organs.
我们实验室最近的研究表明，大鼠、小鼠和鸽子的肝脏在体外可分泌一种催乳素协同活性物质（协同催乳素）。因此，我们研究了催乳素和/或生长激素是否能刺激鸽子肝脏或肾脏分泌协同催乳素。幼鸟每天接受两次磷酸盐缓冲盐水、羊催乳素（oPRL）或羊生长激素（oGH）注射，持续5天。在第6天，取出它们的肝脏和肾脏，并将这些器官的切片在199培养基中孵育4小时。将培养基样本过滤并稀释，然后在本地鸽子嗉囊生物测定法中检测催乳素样活性和协同催乳素活性。后一项检测包括向培养基样本中添加1.0微克oPRL的剂量。单独检测时，肝脏或肾脏培养基样本均无催乳素样活性。只有来自注射催乳素的鸽子的肝脏孵育培养基含有大量的协同催乳素活性。我们的下一个实验旨在确定催乳素对肝脏分泌协同催乳素的刺激是否涉及该激素在体内对肝脏的直接作用。将连接有一段管道和一个渗透微型泵的导管插入鸽子的肠静脉，泵和管道留在腹部。通过这种方式，将溶剂或溶剂中的生长激素或催乳素脉冲注入（每天4次，每次2小时）肠静脉引流。因此，这些激素通过肝门静脉直接输送到肝脏。在输注的7天中的最后3天，鸽子在嗉囊的对侧叶上每天接受两次磷酸盐缓冲盐水或oPRL注射。肝内输注催乳素而非生长激素，导致嗉囊对局部注射催乳素的反应显著增强。将相同剂量的oPRL脉冲注入鸽子的颈外静脉则没有这种效果；因此，这似乎是由肝脏介导的。这些结果表明，催乳素对肝脏的作用之一是刺激一种因子（协同催乳素）的分泌，该因子与该激素协同作用以促进其靶器官的生长。
