Barash I, Madar Z, Gertler A
Mol Cell Endocrinol. 1986 Aug;46(3):235-44. doi: 10.1016/0303-7207(86)90005-5.
Short-term regulation of prolactin (PRL) receptors was studied in ketamine-anaesthetized 18-day pregnant or 7-day lactating female rats, by infusing them with various doses of oPRL or human growth hormone (hGH) for 0-3 h and measuring the binding of [125I]oPRL of [125I]hGH to the microsomal fractions prepared from the liver, mammary gland and kidneys of animals sacrificed at various states of infusion. Our main findings are: In pregnant rats, only 30% of liver receptors are unoccupied and infusion with 25 micrograms/h for 3 h of either oPRL of hGH decreased both free and total receptors by 22-30% while infusion with 250 micrograms/ml caused an additional decrease only in the free receptors. In the mammary gland and the kidney of pregnant rats, all receptors seem to be unoccupied; infusion with 25 micrograms/ml had none or a slight elevating effect on the number of both free and total receptors in the mammary gland but caused a significant 3-fold increase in the kidney; infusion with 250 micrograms/ml, however, resulted in a slight decrease in the mammary gland and a significant decrease in the kidney in both total and free receptors. In the liver of the lactating rats, there was no significant difference between the number of free and total receptors, but in mammary gland, specific binding to the total receptor was higher than to the free ones indicating partial occupancy; infusion with 25 micrograms/ml caused a significant decrease in free and total liver receptors without a remarkable change in the mammary gland and some decrease (by infusion with hGH only) in the kidney. In all cases, the changes in the specific binding resulted from the increase or decrease in receptor number and not from the change in receptor-hormone affinity. In almost all cases, infusion with oPRL or hGH yielded similar results. Infusion with both hormones did not affect the level of the endogenous rat prolactin. In conclusion, our results indicate the short-term regulation of PRL receptors by exogenous hormones is a complicated process which is affected by the level of the infused hormone, physiological state of the animal and may yield, simultaneously, different or even opposite changes in receptor number in various organs.
在氯胺酮麻醉的18天孕龄或7天哺乳期雌性大鼠中研究了催乳素（PRL）受体的短期调节。给大鼠输注不同剂量的oPRL或人生长激素（hGH）0 - 3小时，并测量在输注不同阶段处死动物的肝脏、乳腺和肾脏制备的微粒体部分中[125I]oPRL或[125I]hGH的结合。我们的主要发现如下：在孕鼠中，肝脏中仅30%的受体未被占据，以25微克/小时的剂量输注oPRL或hGH 3小时会使游离和总受体均减少22 - 30%，而以250微克/毫升的剂量输注仅使游离受体进一步减少。在孕鼠的乳腺和肾脏中，所有受体似乎均未被占据；以25微克/毫升的剂量输注对乳腺中游离和总受体数量无影响或仅有轻微升高作用，但使肾脏中的受体数量显著增加3倍；然而，以250微克/毫升的剂量输注会使乳腺中受体数量略有减少，肾脏中总受体和游离受体数量均显著减少。在泌乳大鼠的肝脏中，游离受体和总受体数量无显著差异，但在乳腺中，与总受体的特异性结合高于游离受体，表明部分受体被占据；以25微克/毫升的剂量输注会使肝脏中游离和总受体数量显著减少，乳腺中无明显变化，肾脏中（仅在输注hGH时）有一定减少。在所有情况下，特异性结合的变化是由受体数量的增加或减少引起的，而非受体 - 激素亲和力的变化。几乎在所有情况下，输注oPRL或hGH产生相似的结果。同时输注两种激素不影响内源性大鼠催乳素水平。总之，我们的结果表明外源性激素对PRL受体的短期调节是一个复杂的过程，受输注激素水平、动物生理状态影响，并且可能同时在不同器官中导致受体数量出现不同甚至相反的变化。
