Zeng Junjia, Li Jie, Yang Kun, Yan Jiayu, Xu Tianchun, Lu Weiqun
National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China.
The Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai, China.
Front Physiol. 2022 Jun 29;13:913233. doi: 10.3389/fphys.2022.913233. eCollection 2022.
Stress coping styles are very common in fish, and investigations into this area can greatly improve fish welfare and promote the sustainable development of aquaculture. Although most studies have focused on the behavioral and physiological differences of these fishes, the endocrine response of different coping styles fish when undergoing salinity challenge is still unclear. We examined the physiological response in olive flounder with active coping (AC) style and passive coping (PC) style after transferred from seawater (SW) to freshwater for 0, 2, 5, 8, and 14 days. The results showed that: 1) the plasma prolactin level of FW-acclimated AC flounder was substantially higher than that of FW-acclimated PC flounder at 5, 8, and 14 days, and the branchial gene expression of prolactin receptor (PRLR) in AC flounder was slightly higher than PC flounder after transfer. While there was no remarkable difference observed in cortisol (COR) levels between AC and PC flounder. After transfer, glucocorticoid receptor (GR) expression in AC flounder was significantly higher compared with PC flounder at 8 days. 2) Branchial NKA-IR ionocytes numbers were reduced in PC flounder after transfer, while ionocytes number remain stable in AC flounder. 3) The branchial stem cell transcription factor gene expression of AC flounder was significantly higher than PC flounder at 2, 5, and 14 days after transfer, while branchial stem cell transcription factor gene expression of FW-acclimated AC flounder was only substantially higher than that of PC flounder at 5 days. 4) As an apoptosis upstream initiator, the branchial gene expression of in PC flounder was considerably higher than in AC flounder after transfer at 8 days. This study revealed that olive flounder with active and passive coping styles have different endocrine coping strategies after facing the low-salinity challenge. AC flounder adopt an active endocrine strategy by increasing ionocyte differentiation and prolactin secretion significantly. In contrast, PC flounder employ a passive strategy of reducing ionocytes differentiation and retaining prolactin content at a low level to reduce branchial ionocytes number.
应激应对方式在鱼类中非常普遍，对这一领域的研究可以极大地改善鱼类福利并促进水产养殖业的可持续发展。尽管大多数研究都集中在这些鱼类的行为和生理差异上，但不同应对方式的鱼类在经受盐度挑战时的内分泌反应仍不清楚。我们研究了将牙鲆从海水（SW）转移到淡水0、2、5、8和14天后，主动应对（AC）型和被动应对（PC）型牙鲆的生理反应。结果表明：1）在第5、8和14天，适应淡水的AC型牙鲆的血浆催乳素水平显著高于适应淡水的PC型牙鲆，转移后AC型牙鲆鳃中催乳素受体（PRLR）的基因表达略高于PC型牙鲆。而AC型和PC型牙鲆的皮质醇（COR）水平没有显著差异。转移后，在第8天，AC型牙鲆的糖皮质激素受体（GR）表达显著高于PC型牙鲆。2）转移后PC型牙鲆鳃中NKA-IR离子细胞数量减少，而AC型牙鲆的离子细胞数量保持稳定。3）转移后第2、5和14天，AC型牙鲆鳃干细胞转录因子基因表达显著高于PC型牙鲆，而适应淡水的AC型牙鲆鳃干细胞转录因子基因表达仅在第5天显著高于PC型牙鲆。4）作为凋亡上游启动因子，转移后第8天，PC型牙鲆鳃中的基因表达显著高于AC型牙鲆。本研究表明，主动和被动应对方式的牙鲆在面临低盐度挑战后具有不同的内分泌应对策略。AC型牙鲆通过显著增加离子细胞分化和催乳素分泌采取主动内分泌策略。相比之下，PC型牙鲆采用被动策略，减少离子细胞分化并将催乳素含量维持在低水平以减少鳃离子细胞数量。
