Grosvenor C E, Shyr S W, Goodman G T, Mena F
Neuroendocrinology. 1986;43(6):679-85. doi: 10.1159/000124604.
The purpose of these studies was to determine the effect of suckling on the plasma oxytocin (OT) concentration profile in conscious primiparous rats during midlactation. Comparisons were made with plasma prolactin (PRL) levels obtained in the same rats. OT levels in the majority of rats exhibited a single peak during the first 5-30 min, then fell rapidly during the course of a 45-min period of suckling. The plasma OT levels were sustained over a longer period in mothers suckling 8 rather than 6 pups; the amplitudes of the OT response were similar, however. By contrast, plasma PRL profiles indicated that a steady secretion of the hormone occurred throughout the suckling period, with suckling of 8 pups resulting in significantly higher plasma levels than suckling of 6 pups. A considerably greater increase in the peak plasma OT concentration resulted when hungry foster litters of 6 pups were suckled after the mothers' own 6 pups had been suckled. Plasma PRL levels during the two sucklings, though, were similar. The rapid onset of the OT response to suckling was seen more clearly in urethane-anesthetized rats following mammary nerve stimulation. Plasma OT levels rose to a peak within 5 s after the onset, then fell to prestimulus levels by the end of the 65-second stimulation period. These results suggest that different regulating mechanisms are involved in the secretory responses of OT and PRL to suckling and that different thresholds of activation are likely to exist for the two hormones.
这些研究的目的是确定哺乳对泌乳中期清醒初产大鼠血浆催产素（OT）浓度变化的影响。并将其与同一批大鼠的血浆催乳素（PRL）水平进行比较。大多数大鼠的OT水平在最初5 - 30分钟内出现一个峰值，然后在45分钟的哺乳过程中迅速下降。哺乳8只幼崽的母鼠血浆OT水平维持的时间比哺乳6只幼崽的母鼠更长；然而，OT反应的幅度相似。相比之下，血浆PRL变化曲线表明，在整个哺乳期间该激素持续稳定分泌，哺乳8只幼崽时的血浆水平显著高于哺乳6只幼崽时。在母鼠自己的6只幼崽哺乳后再哺乳6只饥饿的寄养幼崽时，血浆OT峰值浓度的增加幅度要大得多。不过，两次哺乳期间的血浆PRL水平相似。在对乳腺神经进行刺激后，在氨基甲酸乙酯麻醉的大鼠中更清楚地观察到OT对哺乳反应的快速启动。刺激开始后5秒内，血浆OT水平升至峰值，然后在65秒的刺激期结束时降至刺激前水平。这些结果表明，OT和PRL对哺乳的分泌反应涉及不同的调节机制，并且这两种激素可能存在不同的激活阈值。
