Damaraland mole rats (Fukomys damarensis) are cooperatively breeding, subterranean mammals, which exhibit high reproductive skew. Reproduction is monopolized by the dominant female of the group, while subordinates are physiologically suppressed. The blockade of reproduction results from an inhibition of ovulation, which is caused by inadequate secretion of luteinizing hormone (LH) from the pituitary, which in turn might be brought about by a disruption of the normal GnRH secretion from the hypothalamus. The neuropeptides dynorphin and neurokinin B are expressed together with kisspeptin in a subpopulation of neurons in the arcuate nucleus (ARC). This neuron population is termed KNDy neurons and is considered to constitute the GnRH pulse generator. To assess whether dynorphin (encoded by the Pdyn gene) and neurokinin B (NKB, encoded by the Tac3 gene) are involved in the mechanism of reproductive suppression we investigated the distribution and gene expression of Pdyn and Tac3 by means of in situ hybridisation in wild-caught female Damaraland mole-rats with different reproductive status. In both reproductive phenotypes, substantial Pdyn expression was found in several brain regions of the telencephalon including the cerebral cortex, the striatum, the hippocampus, the amygdala and the olfactory tubercle. Within the hypothalamus Pdyn expression occurred in the paraventricular nucleus, the dorsomedial nucleus, the supraoptic nucleus, the ventromedial nucleus and the ARC. Prominent Tac3 expression was found in the habenula, the bed nucleus of the stria terminalis, the cerebral cortex, the striatum, the hippocampus, the amygdala, the dorsomedial nucleus, the ARC and the lateral mammillary nucleus. Quantification of the gene expression levels in the ARC revealed decreased Pdyn and increased Tac3 expression in breeding compared to nonbreeding females. This suggests that both neuropeptides play a role in the regulation of reproduction in Damaraland mole-rats. Their exact role in mediating the inhibition of GnRH release in nonbreeding females remains to be determined.

中文翻译：

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雌性达马拉兰鼹鼠的生殖状态依赖性强啡肽和神经激肽 B 基因表达

达马拉兰鼹鼠 (Fukomys damarensis) 是合作繁殖的地下哺乳动物，它们表现出高度的生殖偏差。繁殖由群体中占主导地位的女性垄断，而下属则在生理上受到抑制。生殖受阻是由排卵抑制引起的，这是由于垂体黄体生成素 (LH) 分泌不足引起的，而这又可能是由于下丘脑正常 GnRH 分泌受到干扰所致。神经肽强啡肽和神经激肽 B 与 Kisspeptin 一起在弓状核 (ARC) 的神经元亚群中表达。这种神经元群被称为 KNDy 神经元，被认为构成了 GnRH 脉冲发生器。为了评估强啡肽（由 Pdyn 基因编码）和神经激肽 B（NKB，由 Tac3 基因编码）参与生殖抑制机制，我们通过原位杂交研究了 Pdyn 和 Tac3 的分布和基因表达，在野生捕获的具有不同生殖状态的雌性 Damaraland 鼹鼠中。在这两种生殖表型中，在端脑的几个大脑区域中发现了大量 Pdyn 表达，包括大脑皮层、纹状体、海马、杏仁核和嗅结节。在下丘脑内，Pdyn 表达发生在室旁核、背内侧核、视上核、腹内侧核和 ARC。在缰核、终纹床核、大脑皮层、纹状体、海马、杏仁核、背内侧核、ARC 和侧乳头核。ARC 中基因表达水平的量化显示，与非繁殖雌性相比，繁殖中 Pdyn 的表达降低，Tac3 的表达增加。这表明这两种神经肽在 Damaraland 鼹鼠的繁殖调节中发挥作用。它们在介导非繁殖雌性 GnRH 释放抑制方面的确切作用仍有待确定。