Luckman S M, Antonijevic I, Leng G, Dye S, Douglas A J, Russell J A, Bicknell R J
Department of Anatomy, University of Cambridge, UK.
J Neuroendocrinol. 1993 Feb;5(1):7-12. doi: 10.1111/j.1365-2826.1993.tb00358.x.
The neuropeptide oxytocin has long been known as a potent contractor of the uterus. However, it has remained difficult to attribute a definite role for neurohypophysial oxytocin in either the initiation or continuation of labour. Most recently, Lefebvre and colleagues have suggested that oxytocin produced in the uterus, rather than in the hypothalamus, may be more important in parturition since at term the uterus of the rat contains 70-fold more mRNA for oxytocin than the hypothalamus, and this disappears at about the time of parturition. Despite the high levels of mRNA the uterus contains only nanogram quantities of immunoreactive oxytocin per gram wet weight at term, compared to microgram quantities present in the pituitary. Here we show that activation of the neurohypophysial oxytocin system occurs, as reflected by expression of immunoreactivity for Fos in the hypothalamic supraoptic nucleus, and that this activation is indeed critical for normal parturition, since its inhibition results in a significant prolongation of parturition. In addition, we present evidence that pulsatile delivery of oxytocin into the circulation is important for the efficient progress of parturition, indicating that a major role of the neuronal circuits regulating oxytocin secretion for parturition, as is already known for suckling, is to produce an appropriately patterned hormonal output for efficient biological action.
神经肽催产素长期以来一直被认为是子宫的强力收缩剂。然而，要确定神经垂体催产素在分娩启动或持续过程中的明确作用仍然很困难。最近，勒费布尔及其同事提出，子宫产生的催产素而非下丘脑产生的催产素在分娩中可能更为重要，因为足月时大鼠子宫中催产素的mRNA含量比下丘脑高70倍，且这种情况在分娩时左右消失。尽管子宫中mRNA水平很高，但足月时每克湿重子宫中仅含有纳克量的免疫反应性催产素，而垂体中则含有微克量。我们在此表明，神经垂体催产素系统被激活，这通过下丘脑视上核中Fos免疫反应性的表达得以体现，而且这种激活对于正常分娩确实至关重要，因为其受到抑制会导致分娩显著延长。此外，我们提供的证据表明，催产素向循环系统的脉冲式释放对于分娩的高效进行很重要，这表明调节分娩时催产素分泌的神经回路的主要作用，如同已知的哺乳情况一样，是产生具有适当模式的激素输出以实现高效的生物学作用。
