Guangdong Research Center on Reproductive Control and Breeding Technology of Indigenous Valuable Fish Species, Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Fisheries College, Guangdong Ocean University, Zhanjiang 524088, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Zhanjiang 524025, China.
Guangdong Research Center on Reproductive Control and Breeding Technology of Indigenous Valuable Fish Species, Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Fisheries College, Guangdong Ocean University, Zhanjiang 524088, China.
Gen Comp Endocrinol. 2022 Jan 15;316:113958. doi: 10.1016/j.ygcen.2021.113958. Epub 2021 Nov 30.
Gonadotropin-releasing hormone (GnRH) is an important neuropeptide in the reproductive system. Although GnRH analogues have been used to artificially spawn pompano (Trachinotus sp.), the native forms of GnRH have not been described in this species. In this study three GnRH subtypes [sea bream GnRH (sbGnRH), chicken GnRH-Ⅱ (cGnRH-Ⅱ) and salmon GnRH (sGnRH)] were identified in pompano (Trachinotus ovatus). cgnrh-Ⅱ and sgnrh were mainly expressed in the brain of male and female fish, showing a tissue-specific expression pattern, while sbgnrh was expressed at different transcriptional levels in all tested tissues. In vivo injection experiment showed that sbGnRH significantly increased fsh and lh genes expression in a dose-dependent manner, but a high concentration of sbGnRH could desensitize the expression of lh. High concentrations of cGnRH-Ⅱ and sGnRH could induce the expression of fsh and lh. In addition, the results of in vitro incubation experiments showed that the high concentration of sbGnRH peptide could induce the expression of fsh and lh, while cGnRH-Ⅱ and sGnRH peptides could only induce the expression of fsh. 17β-estradiol (E) and 17α-methyltestosterone (MT) significantly inhibited sbgnrh mRNA expression in a dose-dependent manner, but did not affect the expression of cgnrh-Ⅱ and sgnrh mRNA. sbGnRH is the main GnRH subtype in pompano. E and MT can play a negative role in the regulation of sbgnrh. This study provides a theoretical basis for the reproductive endocrinology of pompano.
促性腺激素释放激素（GnRH）是生殖系统中的一种重要神经肽。尽管 GnRH 类似物已被用于人工催产马鲛鱼（Trachinotus sp.），但该物种的内源性 GnRH 形式尚未被描述。本研究在马鲛鱼（Trachinotus ovatus）中鉴定出三种 GnRH 亚型[海鲷 GnRH（sbGnRH）、鸡 GnRH-Ⅱ（cGnRH-Ⅱ）和鲑鱼 GnRH（sGnRH）]。cgnrh-Ⅱ和 sgnrh 主要在雌雄鱼的脑中表达，表现出组织特异性表达模式，而 sbgnrh 在所有测试组织中的表达水平不同。体内注射实验表明，sbGnRH 以剂量依赖性方式显著增加 fsh 和 lh 基因的表达，但高浓度的 sbGnRH 可能使 lh 的表达脱敏。高浓度的 cGnRH-Ⅱ和 sGnRH 可诱导 fsh 和 lh 的表达。此外，体外孵育实验结果表明，高浓度 sbGnRH 肽可诱导 fsh 和 lh 的表达，而 cGnRH-Ⅱ和 sGnRH 肽仅可诱导 fsh 的表达。17β-雌二醇（E）和 17α-甲基睾酮（MT）以剂量依赖性方式显著抑制 sbgnrh mRNA 的表达，但不影响 cgnrh-Ⅱ和 sgnrh mRNA 的表达。sbGnRH 是马鲛鱼的主要 GnRH 亚型。E 和 MT 可在 sbgnrh 的调节中发挥负作用。本研究为马鲛鱼生殖内分泌学提供了理论基础。
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