Boer K, Lincoln D W, Swaab D F
J Endocrinol. 1975 May;65(2):163-76. doi: 10.1677/joe.0.0650163.
Labour was studied in 69 primiparous and multiparous rats by continuous observation and by the recording of intra-uterine activity. The effect of electrical stimulation of the neurohypophysis with stimulation parameters selected to create a pulsatile release of oxytocin was investigated. Stimulation was applied to the neurohypophysis through chronically implanted electrodes every 5 min, in 45 min sessions, from noon on Day 21 of gestation and at 3 h intervals thereafter. Electrical stimulation successfully promoted (or induced) the onset and facilitated the course of labour. Stimulation at 12.00 h on Day 21, or at a subsequent stimulation session 3, 6, 9 or more hours later, promoted an immediate increase in the frequency and amplitude of uterine contractions. Overt signs of abdominal straining followed within 5-30 min and the first pup was delivered shortly thereafter. These 'induced' deliveries were almost identical to those displayed by control rats; labour continued to completion despite the termination of the stimulation session after 45 min. By contrast, one third of the stimulated animals displayed an interrupted pattern of labour in which events virtually ceased for 30-60 min when stimulation was terminated. Stimulation, however, only advanced labour by 1-2 h in relation to control animals; this was not statistically significant. Stimulation accelerated the delivery of the first 5 pups in each litter. In both stimulated and control animals, the birth intervals declined over these first few deliveries to reach the lowest values of 5-6 min throughout the remainder of labour. The most common litter size was 12 pups. The distribution of labour on Day 21 and 22 was bimodal. Seventy per cent of the animals gave birth between 12.00 and 18.00 h on Day 21, a few gave birth during the following night and the remainder formed a second peak on Day 22. All litters of less than 6 pups were born during this later period. The implications of these results in the context of spontaneous labour are discussed. We conclude that endogenous oxytocin (with perhaps other neurohypophysial hormones) released in pulses of 1-3 mu. every 5 min can promote a pattern of labour on Day 21 of gestation that is almost indistinguishable from that which occurs naturally.
通过连续观察和记录子宫内活动，对69只初产和经产大鼠的分娩过程进行了研究。研究了以选定的刺激参数对神经垂体进行电刺激以产生催产素脉冲式释放的效果。从妊娠第21天中午开始，每隔5分钟通过长期植入的电极对神经垂体进行刺激，每次刺激持续45分钟，此后每隔3小时进行一次。电刺激成功促进（或诱导）了分娩的开始并促进了分娩过程。在第21天12:00进行刺激，或在随后3、6、9小时或更长时间后的刺激过程中，子宫收缩的频率和幅度立即增加。5 - 30分钟内出现明显的腹部用力迹象，此后不久第一只幼崽出生。这些“诱导”分娩与对照大鼠的分娩几乎相同；尽管刺激过程在45分钟后终止，但分娩仍持续至结束。相比之下，三分之一的受刺激动物表现出分娩中断模式，即当刺激终止时，分娩过程实际上会停止30 - 60分钟。然而，与对照动物相比，刺激仅使分娩提前1 - 2小时；这在统计学上不显著。刺激加速了每窝前5只幼崽的分娩。在受刺激和对照动物中，在最初几次分娩过程中，幼崽出生间隔均下降，在整个剩余分娩过程中达到5 - 6分钟的最低值。最常见的窝产仔数为12只。第21天和第22天的分娩分布呈双峰状。70%的动物在第21天12:00至18:00之间分娩，少数在随后的夜间分娩，其余在第22天形成第二个峰值。所有少于6只幼崽的窝均在后期出生。讨论了这些结果在自然分娩背景下的意义。我们得出结论，每5分钟以1 - 3微单位的脉冲形式释放的内源性催产素（可能还有其他神经垂体激素）可促进妊娠第21天的分娩模式，这种模式与自然发生的模式几乎无法区分。
