Department of Animal Science, Texas A&M University, College Station, TX 77843-241, USA.
J Neuroendocrinol. 2011 Sep;23(9):815-22. doi: 10.1111/j.1365-2826.2011.02177.x.
Onset of puberty is characterised by a marked increase in the frequency of release of gonadotrophin-releasing hormone (GnRH) and luteinising hormone (LH). The Kiss1 gene plays a critical role in pubertal development, and its product, kisspeptin, stimulates GnRH and LH release. In the present study, we tested the hypothesis that Kiss1 gene expression in the preoptic area (POA) and hypothalamus increases during maturation of the reproductive neuroendocrine axis in association with increased LH pulsatility. Ovariectomised, oestradiol-replaced lambs were euthanised at 25, 30 and 35 weeks of age. Blood samples were collected before euthanasia to characterise the pattern of LH release. Kiss1 mRNA was detected in coronal sections of the POA and hypothalamus and Kiss1-expressing cells were identified on the basis of silver grain density. The mean number of Kiss1-expressing cells in the POA/periventricular (PeV) areas increased from 25 to 30 weeks of age. No further increase at 35 weeks of age was observed, and the changes in Kiss1 expression in the POA/PeV were independent of changes in LH pulse frequency. The mean number of Kiss1-expressing cells in the arcuate (ARC) nucleus did not differ among age groups, although it was greater in the middle ARC of lambs exhibiting increased frequency of LH release. The density of silver grains per cell did not differ among groups in any of the areas studied. The results obtained indicate that the Kiss1 gene is activated in the POA/PeV and ARC of ewe lambs during juvenile development, and that kisspeptin neurones in the middle ARC, in particular, are involved in the acceleration of pulsatile LH release during maturation of the reproductive neuroendocrine axis in ewe lambs.
青春期的开始以促性腺激素释放激素 (GnRH) 和黄体生成素 (LH) 释放频率的显著增加为特征。 Kiss1 基因在青春期发育中起着关键作用，其产物 kisspeptin 刺激 GnRH 和 LH 的释放。在本研究中，我们检验了这样一个假设，即在生殖神经内分泌轴成熟过程中， Kiss1 基因在视前区（POA）和下丘脑的表达增加与 LH 脉冲性增加有关。在 25、30 和 35 周龄时，对去卵巢、雌激素替代的羔羊进行安乐死。在安乐死前采集血样以描述 LH 释放模式。在 POA 和下丘脑的冠状切片中检测到 Kiss1 mRNA，并根据银粒密度鉴定 Kiss1 表达细胞。POA/室旁（PeV）区 Kiss1 表达细胞的平均数量从 25 周龄增加到 30 周龄。在 35 周龄时没有观察到进一步的增加，并且 POA/PeV 中 Kiss1 表达的变化与 LH 脉冲频率的变化无关。在各年龄组中，ARC 核中的 Kiss1 表达细胞的平均数量没有差异，尽管在表现出 LH 释放频率增加的羔羊的中间 ARC 中， Kiss1 表达细胞的数量更多。在所研究的任何区域中，细胞内银粒密度在各组之间均无差异。研究结果表明，在幼羊发育过程中， Kiss1 基因在 POA/PeV 和 ARC 中被激活，特别是中间 ARC 的 kisspeptin 神经元参与了母羊生殖神经内分泌轴成熟过程中脉冲性 LH 释放的加速。
