Briffaud Virginie, Williams Paul, Courty Justine, Broberger Christian
Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 171 77 Stockholm, Sweden
Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 171 77 Stockholm, Sweden.
J Neurosci. 2015 Mar 11;35(10):4229-37. doi: 10.1523/JNEUROSCI.2633-14.2015.
Milk production in the nursing mother is induced by the hormone prolactin. Its release from the anterior pituitary is generally under tonic inhibition by neuroendocrine tuberoinfundibular dopamine (TIDA) neurons of the arcuate nucleus. Successful nursing, however, requires not only production but also ejection of breast milk. This function is supported by the hormone oxytocin. Here we explored the possibility that interaction between these functionally complementary hormones is mediated by TIDA neurons. First, whole-cell patch-clamp recordings were performed on prepubertal male rat hypothalamic slices, where TIDA neurons can be identified by a robust and rhythmic membrane potential oscillation. Oxytocin induced a switch of this rhythmic activity to tonic discharge through a depolarization involving direct actions on TIDA neurons. The depolarization is sensitive to blockade of the oxytocin receptor and is mediated by a voltage-dependent inward current. This inward current has two components: a canonical transient receptor potential-like conductance in the low-voltage range, and in the high-voltage range, a Ca(2+)-dependent component. Finally, whole-cell and loose-patch recordings were also performed on slices from virgin and lactating female rats to evaluate the relevance of these findings for nursing. In these preparations, oxytocin was found to excite TIDA neurons, identified by their expression of tyrosine hydroxylase. These findings suggest that oxytocin can modulate prolactin secretion by exciting TIDA neurons, and that this may serve as a feedforward inhibition of prolactin release.
哺乳期母亲的乳汁分泌是由催乳素诱导的。催乳素从前叶垂体释放通常受到弓状核神经内分泌结节漏斗多巴胺（TIDA）神经元的紧张性抑制。然而，成功哺乳不仅需要乳汁分泌，还需要乳汁排出。这种功能由催产素支持。在这里，我们探讨了这些功能互补的激素之间的相互作用是否由TIDA神经元介导的可能性。首先，对青春期前雄性大鼠下丘脑切片进行全细胞膜片钳记录，在该切片中，TIDA神经元可通过强烈且有节律的膜电位振荡来识别。催产素通过涉及对TIDA神经元直接作用的去极化作用，使这种节律性活动转变为紧张性放电。这种去极化对催产素受体的阻断敏感，并由电压依赖性内向电流介导。这种内向电流有两个成分：低电压范围内的一种典型瞬时受体电位样电导，以及高电压范围内的一种钙依赖性成分。最后，还对未生育和哺乳期雌性大鼠的切片进行了全细胞和 loose - patch 记录，以评估这些发现与哺乳的相关性。在这些标本中，发现催产素能兴奋通过酪氨酸羟化酶表达鉴定的TIDA神经元。这些发现表明，催产素可通过兴奋TIDA神经元来调节催乳素分泌，并且这可能作为对催乳素释放的一种前馈抑制。
