After the discovery of Gonadotropin-inhibitory hormone (GnIH) in birds in 2000, it showed different roles in different vertebrate classes and even in different species of same classes. In birds and mammals, GnIH inhibits the expression of gonadotropins during reproduction, while in fishes it exerts both inhibitory and stimulatory effect on reproduction. The current study evaluates the role of GnIH during reproduction in Labeo catla. The partial cDNA sequence of GnIHR1 and GnIHR3 receptor genes was identified by degenerate PCR. The mRNA expression analysis of GnIHRs during different reproductive phases showed that the expression of all three GnIH receptor genes is highest during spawning phase. The expression of GnIH receptors is detected in both brain and gonads except for GnIHR3 which only expressed in gonads. The in vivo experiments with GnIH antagonist, RF313 drastically reduced the expression level of reproduction related genes like LH, FSH, and GnRH at 1 h post-injection. In another experiment the surge induced by cGnIH-III peptide on gonadotropins gene expression is further increased when co-injected with LHRHa. However, co-injection of melatonin along with cGnIH-III peptide had opposite effects. These results showed that the GnIH/GnIHRs system has positive effect on reproduction in L. catla.

2000年在鸟类中发现促性腺激素抑制激素（GnIH）后，在不同脊椎动物纲甚至同一纲的不同物种中表现出不同的作用。在鸟类和哺乳动物中，GnIH 在繁殖过程中抑制促性腺激素的表达，而在鱼类中，它对繁殖具有抑制和刺激作用。目前的研究评估了 GnIH 在Labeo catla繁殖过程中的作用. 通过简并PCR鉴定GnIHR1和GnIHR3受体基因的部分cDNA序列。GnIHR在不同生殖阶段的mRNA表达分析表明，所有三个GnIH受体基因的表达在产卵阶段最高。除了仅在性腺中表达的 GnIHR3 外，在脑和性腺中均检测到 GnIH 受体的表达。使用 GnIH 拮抗剂 RF313 进行的体内实验在注射后 1 小时显着降低了生殖相关基因如 LH、FSH 和 GnRH 的表达水平。在另一项实验中，当与 LHRHa 共同注射时，cGnIH-III 肽诱导的促性腺激素基因表达激增进一步增加。然而，褪黑激素与 cGnIH-III 肽的共同注射具有相反的效果。L. catla