Gonadotropin-releasing hormone (GnRH) controls synthesis of sex steroid hormones through hypothalamic-pituitary-gonadal (HPG) axis in vertebrates. But in mollusks, research on GnRH and steroidogenesis pathways is still limited. In this study, we first identified two gonadotropin receptor like genes (LGR and LGR5L) and four steroidogenesis-related genes (CYP17A, HSD17B12, HSD3B1 and HSD3B2) in the scallop Patinopecten yessoensis. By examining the expression of 11 genes in the ganglia and/or gonad as well as the concentration of progesterone, testosterone and estradiol in the gonad, we postulate that a potential GnRH signaling pathway (GnRH-GnRHR-GPB5-LGR/LGR5L) in the cerebral and pedal ganglia (CPG) and steroidogenesis pathway (CYP17A, HSD17B12 and HSD3B1) in the gonad are involved in regulating sex steroid hormones. E₂/T index that indicates aromatase activity is higher in the ovary than testis and is positively correlated with the expression of FOXL2 in the gonad, implying the presence of aromatase in the scallop. In addition, we confirmed that expression of most of the downstream genes in the two pathways was significantly elevated after injection of mature py-GnRH peptide. This study would contribute to a new understanding of the molecular basis underlying reproduction regulation by GnRH in mollusks.

促性腺激素释放激素（GnRH）通过下丘脑-垂体-性腺（HPG）轴控制脊椎动物中性类固醇激素的合成。但是在软体动物中，有关GnRH和类固醇生成途径的研究仍然很有限。在这项研究中，我们首先在扇贝Patinopecten yessoensis中鉴定了两个促性腺激素受体样基因（LGR和LGR5L）和四个类固醇生成相关基因（CYP17A，HSD17B12，HSD3B1和HSD3B2）。通过检查神经节和/或性腺中11个基因的表达以及性腺中孕酮，睾丸激素和雌二醇的浓度，我们推测其潜在的GnRH信号传导途径（GnRH-GnRHR-GPB5-LGR / LGR5L）脑和踏板神经节（CPG）和类固醇生成途径（CYP17A，HSD17B12和性腺中的HSD3B1）参与调节性类固醇激素。E ₂ / T指数表明卵巢中的芳香化酶活性高于睾丸，并且与性腺中FOXL2的表达呈正相关，这意味着扇贝中芳香化酶的存在。另外，我们证实注射成熟的py-GnRH肽后，两条途径中大多数下游基因的表达均显着升高。这项研究将有助于对GnRH在软体动物中生殖调控的分子基础的新认识。