Department of Mathematics and Programs in Neuroscience and Molecular Biophysics, Florida State University, Tallahassee, FL, USA.
J Neuroendocrinol. 2010 Jul;22(7):778-84. doi: 10.1111/j.1365-2826.2010.02012.x. Epub 2010 Apr 29.
Hormone secretion often occurs in a pulsatile manner. In this review, we discuss two rhythms of in vivo prolactin release in female rats and the ongoing research that we and others have performed aiming to understand the mechanisms underlying them. The peptide hormone oxytocin appears to play an important role in both rhythms. One rhythm occurs during the first half of pregnancy, but can also be induced in ovariectomised rats. This is characterised by a circadian pattern with two prolactin surges per day. Two methods for triggering this rhythm are discussed, each utilising a unique physiological pathway that includes oxytocin action, presumably on pituitary lactotrophs. The second rhythm occurs during the oestrous cycle and is characterised by a surge of prolactin on the afternoon of pro-oestrus. We discuss recent findings that oxytocin is more effective at stimulating prolactin release from lactotrophs taken from animals on the afternoon of pro-oestrus than from those of animals on the morning of dioestrus 1, raising the possibility that this hormone plays a physiological role in the regulation of prolactin secretion during the oestrous cycle.
激素分泌通常呈脉冲式。在这篇综述中，我们讨论了两种雌性大鼠体内催乳素释放的节律，以及我们和其他人进行的旨在了解其背后机制的正在进行的研究。肽激素催产素似乎在这两种节律中都起着重要作用。一种节律发生在妊娠的前半段，但也可以在卵巢切除的大鼠中诱导。其特征是每天有两个催乳素峰的昼夜节律。讨论了两种触发这种节律的方法，每种方法都利用了一种独特的生理途径，包括催产素作用，可能作用于垂体催乳素细胞。第二种节律发生在发情周期中，其特征是发情前期下午催乳素的激增。我们讨论了最近的发现，即来自发情前期下午动物的催乳素细胞对催产素的反应比来自发情后期 1 天上午动物的催乳素细胞更有效，这增加了这种激素在发情周期中调节催乳素分泌的生理作用的可能性。
