Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-910, Brazil.
Brain Res Bull. 2012 Sep 1;88(6):566-73. doi: 10.1016/j.brainresbull.2012.06.004. Epub 2012 Jun 23.
In female rats, stimulation of the uterine cervix during mating induces two daily surges of prolactin. Inhibition of hypothalamic dopamine release and stimulation of oxytocin neurons in the paraventricular nucleus (PVN) are required for prolactin secretion. We aim to better understand how stimulation of the uterine cervix is translated into two daily prolactin surges. We hypothesize that noradrenergic neurons in the A1, A2, and locus coeruleus (LC) are responsible for conveying the peripheral stimulus to the PVN. In order to determine whether projections from these neurons to the PVN are activated by cervical stimulation (CS), we injected a retrograde tracer, Fluoro-Gold (FG), into the PVN of ovariectomized rats. Fourteen days after injection, animals were submitted to artificial CS or handling and perfused with a fixative solution. Brains were removed and sectioned from the A1, A2, and LC for c-Fos, tyrosine hydroxylase (TH), and FG triple-labeling using immunohistochemistry. CS increased the percentage of TH/FG+ double-labeled neurons expressing c-Fos in the A1 and LC. CS also increased the percentage of TH+ neurons expressing c-Fos within the A1 and A2, independent of their projections to the PVN. Our data reinforce the significant contributions of the A1 and A2 to carry sensory information during mating, and provide evidence of a functional pathway in which CS activates A1 and LC neurons projecting to the PVN, which is potentially involved in the translation of CS into two daily prolactin surges.
在雌性大鼠中，交配时子宫颈的刺激会引发两次催乳素的日峰。催乳素分泌需要下丘脑多巴胺释放的抑制和室旁核（PVN）中催产素神经元的刺激。我们旨在更好地理解子宫颈刺激如何转化为两次每日催乳素激增。我们假设 A1、A2 和蓝斑（LC）中的去甲肾上腺素能神经元负责将外周刺激传递到 PVN。为了确定这些神经元到 PVN 的投射是否被子宫颈刺激（CS）激活，我们将逆行示踪剂 Fluoro-Gold（FG）注射到卵巢切除大鼠的 PVN 中。注射后 14 天，动物接受人工 CS 或处理，并在固定溶液中灌注。取出大脑并从 A1、A2 和 LC 中进行 c-Fos、酪氨酸羟化酶（TH）和 FG 的三重免疫标记。CS 增加了 A1 和 LC 中表达 c-Fos 的 TH/FG+双标记神经元的百分比。CS 还增加了 A1 和 A2 中表达 c-Fos 的 TH+神经元的百分比，而与它们到 PVN 的投射无关。我们的数据强化了 A1 和 A2 在交配过程中传递感觉信息的重要贡献，并提供了证据表明 CS 激活投射到 PVN 的 A1 和 LC 神经元的功能途径，这可能参与了 CS 转化为两次每日催乳素激增。
