KNDy (kisspeptin/neurokinin B/dynorphin) neurons of the arcuate nucleus (ARC) appear to mediate the negative feedback actions of estradiol and are thought to be key regulators of pulsatile LH secretion. In the ewe, KNDy neurons may also be involved with the positive feedback actions of estradiol (E(2)) to induce the LH surge, but the role of kisspeptin neurons in the preoptic area (POA) remains unclear. The goal of this study was to identify which population(s) of kisspeptin neurons is (are) activated during the LH surge and in response to the removal of E(2)-negative feedback, using Fos as an index of neuronal activation. Dual-label immunocytochemistry for kisspeptin and Fos was performed on sections containing the ARC and POA from ewes during the luteal phase of the estrous cycle, or before or after the onset of the LH surge (experiment 1), and from ovary-intact, short-term (24 h) and long-term (>30 d) ovariectomized (OVX) ewes in anestrus (experiment 2). The percentage of kisspeptin neurons expressing Fos in both the ARC and POA was significantly higher during the LH surge. In contrast, the percentage of kisspeptin/Fos colocalization was significantly increased in the ARC, but not POA, after both short- and long-term E(2) withdrawal. Thus, POA kisspeptin neurons in the sheep are activated during, and appear to contribute to, E(2)-positive feedback, whereas ARC kisspeptin (KNDy) neurons are activated during both surge and pulsatile modes of secretion and likely play a role in mediating both positive and negative feedback actions of E(2) on GnRH secretion in the ewe.

译文

弓形核(ARC)的:KNDy(kisspeptin /神经激肽B / dynorphin)神经元似乎介导雌二醇的负反馈作用,被认为是脉动性LH分泌的关键调节因子。在母羊中,KNDy神经元也可能参与了雌二醇的正反馈作用(E(2))以诱导LH激增,但尚不清楚视蛋白在视前区(POA)中的作用。这项研究的目的是使用Fos作为神经元激活的指标,确定在LH激增过程中激活了哪些基肽素神经元群体,并响应于去除E(2)负反馈而被激活。在发情周期的黄体期,LH激增发作之前或之后(实验1)以及卵巢完整,短时,对包含ARC和POA的母羊切片进行kisseptin和Fos的双标记免疫细胞化学分析期(24小时)和长期(> 30 d)卵巢切除卵巢(OVX)母羊(实验2)。在LH激增期间,在ARC和POA中表达Fos的Kisspeptin神经元的百分比显着较高。相反,在短期和长期撤出E(2)后,ARC中kisepteptin / Fos共定位的百分比显着增加,但POA没有显着增加。因此,绵羊中的POA Kisspeptin神经元在E(2)阳性反馈过程中被激活,并且似乎有助于E(2)阳性反馈,而ARC Kisspeptin(KNDy)神经元在激增和搏动性分泌模式下均被激活,并且可能在介导中发挥作用E(2)对母羊GnRH分泌的正反馈和负反馈作用。

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