Goodman Robert L, Lehman Michael N, Smith Jeremy T, Coolen Lique M, de Oliveira Cleusa V R, Jafarzadehshirazi Mohammad R, Pereira Alda, Iqbal Javed, Caraty Alain, Ciofi Philippe, Clarke Iain J
Department of Physiology and Pharmacology, West Virginia University, Morgantown, West Virginia, USA.
Endocrinology. 2007 Dec;148(12):5752-60. doi: 10.1210/en.2007-0961. Epub 2007 Sep 6.
Kisspeptin is a potent stimulator of GnRH secretion that has been implicated in the feedback actions of ovarian steroids. In ewes, the majority of hypothalamic kisspeptin neurons are found in the arcuate nucleus (ARC), with a smaller population located in the preoptic area. Most arcuate kisspeptin neurons express estrogen receptor-alpha, as do a set of arcuate neurons that contain both dynorphin and neurokinin B (NKB), suggesting that all three neuropeptides are colocalized in the same cells. In this study we tested this hypothesis using dual immunocytochemistry and also determined if kisspeptin neurons contain MSH or agouti-related peptide. To assess colocalization of kisspeptin and dynorphin, we used paraformaldehyde-fixed tissue from estrogen-treated ovariectomized ewes in the breeding season (n = 5). Almost all ARC, but no preoptic area, kisspeptin neurons contained dynorphin. Similarly, almost all ARC dynorphin neurons contained kisspeptin. In experiment 2 we examined colocalization of kisspeptin and NKB in picric-acid fixed tissue collected from ovary intact ewes (n = 9). Over three quarters of ARC kisspeptin neurons also expressed NKB, and a similar percentage of NKB neurons contained kisspeptin. In contrast, no kisspeptin neurons stained for MSH or agouti-related peptide. These data demonstrate that, in the ewe, a high percentage of ARC kisspeptin neurons also produce dynorphin and NKB, and we propose that a single subpopulation of ARC neurons contains all three neuropeptides. Because virtually all of these neurons express estrogen and progesterone re-ceptors, they are likely to relay the feedback effects of these steroids to GnRH neurons to regulate reproductive function.
亲吻素是促性腺激素释放激素（GnRH）分泌的强效刺激剂，与卵巢甾体激素的反馈作用有关。在母羊中，大多数下丘脑亲吻素神经元位于弓状核（ARC），少量位于视前区。大多数弓状核亲吻素神经元表达雌激素受体α，一组同时含有强啡肽和神经激肽B（NKB）的弓状核神经元也表达该受体，这表明这三种神经肽共定位于同一细胞中。在本研究中，我们使用双重免疫细胞化学检测了这一假设，并确定亲吻素神经元是否含有促黑素（MSH）或刺鼠相关肽。为了评估亲吻素和强啡肽的共定位情况，我们使用了繁殖季节经雌激素处理的去卵巢母羊（n = 5）的多聚甲醛固定组织。几乎所有ARC的亲吻素神经元都含有强啡肽，但视前区的亲吻素神经元未检测到。同样，几乎所有ARC的强啡肽神经元都含有亲吻素。在实验2中，我们检测了从卵巢完整的母羊（n = 9）收集的苦味酸固定组织中亲吻素和NKB的共定位情况。超过四分之三的ARC亲吻素神经元也表达NKB，且类似比例的NKB神经元含有亲吻素。相比之下，没有亲吻素神经元被促黑素或刺鼠相关肽染色。这些数据表明，在母羊中，高比例的ARC亲吻素神经元也产生强啡肽和NKB，我们推测ARC神经元的一个单一亚群包含所有这三种神经肽。由于几乎所有这些神经元都表达雌激素和孕激素受体，它们可能将这些甾体激素的反馈作用传递给GnRH神经元以调节生殖功能。
