National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China.
National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China.
Gen Comp Endocrinol. 2021 Jun 1;307:113754. doi: 10.1016/j.ygcen.2021.113754. Epub 2021 Mar 10.
Gonadotropin-releasing hormone (GnRH) is considered a key player in reproduction. The caudal neurosecretory system (CNSS) is a unique neurosecretory structure of fish that may be involved in osmoregulation, nutrition, reproduction, and stress-related responses. However, a direct effect of GnRH on Dahlgren cells remains underexplored. Here, we examined the electrophysiological response of Dahlgren cell population of the CNSS to GnRH analog LHRH-A and the transcription of related key genes of CNSS. We found that GnRH increased overall firing frequency and may be changed the firing pattern from silent to burst or phasic firing in a subpopulation of Dahlgren cells. The effect of GnRH on a subpopulation of Dahlgren cells firing activity was blocked by the GnRH receptor (GnRH-R) antagonist cetrorelix. A positive correlation was observed between the UII and GnRH-R mRNA levels in CNSS or gonadosomatic index (GSI) during the breeding season. These findings are the first demonstration of the ability of GnRH acts as a modulator within the CNSS and add to our understanding of the physiological role of the CNSS in reproduction and seasonal adaptation.
促性腺激素释放激素（GnRH）被认为是生殖的关键因素。尾神经分泌系统（CNSS）是鱼类特有的神经分泌结构，可能参与渗透调节、营养、生殖和应激相关反应。然而，GnRH 对 Dahlgren 细胞的直接作用仍未得到充分探索。在这里，我们检查了 CNSS 的 Dahlgren 细胞群体对 GnRH 类似物 LHRH-A 的电生理反应和 CNSS 相关关键基因的转录。我们发现 GnRH 增加了整体放电频率，并可能使 Dahlgren 细胞亚群的放电模式从沉默变为爆发或相位放电。GnRH 对 Dahlgren 细胞亚群放电活动的影响被 GnRH 受体（GnRH-R）拮抗剂 cetrorelix 阻断。在繁殖季节，CNSS 或性腺体指数（GSI）中 UII 和 GnRH-R mRNA 水平之间存在正相关。这些发现首次证明了 GnRH 作为 CNSS 内调节剂的作用，并增加了我们对 CNSS 在生殖和季节性适应中的生理作用的理解。
