追逐驱赶所引起的胁迫对鱼类先天性防御能力的影响(英文)

Effect of Chased and Rammed Stress on Innate Defense Activity of Fish

研究了由追著驱赶引起的胁迫对斑尾鲈先天性防御能力的影响。斑尾鲈具有好斗相残性,实验中观察到,将不同个体大小的斑尾鲈放入同一水体中几小时后,个体稍大的追逐驱赶个体稍小的,处于生态主导地位,而小鱼则处于从属地位。对小鱼血浆内的皮质醇含量进行测定,其值显著高于大鱼血浆内皮质醇的含量,处于胁迫当中。注射灭活细菌到鱼鳔内,游向鱼鳔的嗜中性粒细胞,受胁迫鱼明显少于非受胁迫鱼。且其吞噬活力和呼吸爆发活力也相应下降。同时,体外研究也表明,胁迫抑制了斑尾鲈嗜酸性粒细胞的脱粒。另外,用爱德华氏菌进行感染,注射皮质醇的鱼表现出明显的易感性。从以上的研究我们可以看出,胁迫环境下,皮质醇含量分泌的增加,损害了斑尾鲈的先天性防御能力,对外来病原微生物的入侵也缺乏相应的抵抗力。

A Study was conducted to evaluate the effect of stress, which is caused by chase and ram on the innate defense activity of spot tail bass. Because spot tail bass (Sciaenops ocellatus) are aggressive, within a few hours of post transferring two fish of different size into an aquarium, large fish always became dominant, and challenged, chased and rammed subordinate small fish. The cortisol concentration in the plasma of the subordinate was significantly increased over that of the dominate, indicating that the subordinate was stressed. The number of neutrophils that migrated to the swim bladder, where formalin killed bacterial cells were injected, was significantly decreased in the subordinate, and their phagocytic and respiratory burst activities were both reduced. A stress hormone, cortisol, also suppressed in vitro degranulation of spot tail bass eosinophilic granular cells, which are thought to contain neutrophil migrating factors in their granules. Artificial challenge with Edwardsiella tarda revealed the elevated susceptibility of the cortisol implanted fish to edwardsiellosis. The results obtained from the present study suggest that secreted cortisol under stressful conditions directly impairs the innate cellular defence in spot tail bass (Sciaenops ocellatus), and therefore the stressed fish fail to defeat invading microorganisms.