Qi Xin, Zhou Wenyi, Li Shuisheng, Liu Yun, Ye Gang, Liu Xiaochun, Peng Chun, Zhang Yong, Lin Haoran
State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals, and the Guangdong Province Key Laboratory for Aquatic Economic Animals, Sun Yat-Sen University, Guangzhou 510275, China; Department of Biology, York University, Toronto, Ontario M3J 1P3, Canada.
State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals, and the Guangdong Province Key Laboratory for Aquatic Economic Animals, Sun Yat-Sen University, Guangzhou 510275, China.
Gen Comp Endocrinol. 2015 Sep 15;221:267-77. doi: 10.1016/j.ygcen.2014.10.017. Epub 2014 Nov 14.
Neurokinin B (NKB) is a member of the tackykinin (TAC) family known to play a critical role in the neuroendocrine regulation of reproduction in mammals. However, its biological functions in teleosts are less clear. The aim of this study was to determine the role of NKB in fish reproduction using goldfish as a model. Two transcripts, TAC3a and TAC3b, which encode several NKBs, including NKBa-13, NKBa-10, NKBb-13, and NKBb-11, were cloned. Phylogenetic analysis revealed that NKBa-10 and NKBb-11 are closely related to mammalian NKB, while NKB-13s are more conserved in teleosts. Quantitative real-time PCR analyses in various tissues showed that TAC3a and TAC3b mRNAs were mainly expressed in the brain. In situ hybridization further detected TAC3a and TAC3b mRNAs in several regions of the brain known to be involved in the regulation of reproduction and metabolism, as well as in the neurohypophysis of the pituitary. To investigate the potential role of NKBs in reproduction, goldfish were injected intraperitoneally with synthetic NKBa-13, -10, NKBb-13, or -11 peptides and the mRNA levels of hypothalamic gonadotropin-releasing hormone (GnRH) and pituitary gonadotropin subunits were measured. NKBa-13, -10, or NKBb-13, but not -11, significantly increased hypothalamic salmon GnRH and pituitary FSHβ and LHβ mRNA levels in both female and male goldfish. Finally, ovariectomy increased, while estradiol replacement reduced, TAC3a mRNA levels without affecting TAC3b expression in the hypothalamus. These data suggest that NKBa-13, -10, and NKBb-13 play a role in mediating the estrogen negative feedback regulation of gonadotropins.
神经激肽B（NKB）是速激肽（TAC）家族的成员之一，已知其在哺乳动物生殖的神经内分泌调节中发挥关键作用。然而，其在硬骨鱼中的生物学功能尚不清楚。本研究的目的是以金鱼为模型确定NKB在鱼类繁殖中的作用。克隆了两个转录本TAC3a和TAC3b，它们编码几种NKB，包括NKBa - 13、NKBa - 10、NKBb - 13和NKBb - 11。系统发育分析表明，NKBa - 10和NKBb - 11与哺乳动物NKB密切相关，而NKB - 13在硬骨鱼中更为保守。对各种组织进行的定量实时PCR分析表明，TAC3a和TAC3b mRNA主要在脑中表达。原位杂交进一步在已知参与生殖和代谢调节的脑的几个区域以及垂体神经垂体中检测到TAC3a和TAC3b mRNA。为了研究NKB在繁殖中的潜在作用，给金鱼腹腔注射合成的NKBa - 13、 - 10、NKBb - 13或 - 11肽，并测量下丘脑促性腺激素释放激素（GnRH）和垂体促性腺激素亚基的mRNA水平。NKBa - 13、 - 10或NKBb - 13，而不是NKBb - 11，显著增加了雌性和雄性金鱼下丘脑鲑鱼GnRH以及垂体FSHβ和LHβ的mRNA水平。最后，卵巢切除增加了下丘脑TAC3a mRNA水平，而雌二醇替代则降低了该水平，且不影响TAC3b的表达。这些数据表明，NKBa - 13、 - 10和NKBb - 13在介导促性腺激素的雌激素负反馈调节中发挥作用。
