Van der Salm A L, Pavlidis M, Flik G, Wendelaar Bonga S E
Department of Animal Ecology and Ecophysiology, Institute for Water and Wetland Research, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands.
Gen Comp Endocrinol. 2006 Feb;145(3):247-53. doi: 10.1016/j.ygcen.2005.09.010. Epub 2005 Oct 25.
The skin colour of red porgy, Pagrus pagrus, can be modified by exposure to different background colours. Red and white background colours brighten the dark skin colour that develops under common culture conditions in red porgy. To assess whether skin colour is also modified by aquaculture related handling stress, we subjected red porgy to 5 min of netting stress combined with air exposure. Fish kept on a white background have: (1) a lighter skin colour, which is not influenced by an acute stressor, (2) a less saturated red colour, which significantly decreases 24h post-handling, and (3) a similar hue as fish kept on a red background. The first plasma parameters to rise after application of the stressor are cortisol, lactate and Na(+); then, glucose levels rose. Other plasma ions (Ca(2+), Cl(-), K(+)) were not affected up to 2h post-stressor, but had decreased at 8 and 24h after handling. Plasma pH decreased over the first 2h post-handling, indicative of plasma acidosis upon air exposure. The acidosis then coincided with increases in plasma lactate levels. As alphaMSH levels were not significantly affected by the stressor while cortisol levels showed a five to tenfold increase, we suggest that following acute stress in red porgy, plasma cortisol release is controlled by ACTH, perhaps in combination with a sympathic stimulation.
真鲷（Pagrus pagrus）的皮肤颜色可通过暴露于不同背景颜色而改变。红色和白色背景颜色会使真鲷在常规养殖条件下形成的深色皮肤变亮。为了评估养殖相关的处理应激是否也会改变皮肤颜色，我们对真鲷施加了5分钟的网捕应激并使其暴露于空气中。饲养在白色背景下的鱼有：（1）较浅的皮肤颜色，不受急性应激源影响；（2）饱和度较低的红色，在处理后24小时显著降低；（3）与饲养在红色背景下的鱼具有相似的色调。施加应激源后首先升高的血浆参数是皮质醇、乳酸和Na⁺；然后，葡萄糖水平升高。其他血浆离子（Ca²⁺、Cl⁻、K⁺）在应激源作用后2小时内未受影响，但在处理后8小时和24小时有所下降。处理后的前2小时血浆pH值下降，表明暴露于空气中时出现血浆酸中毒。这种酸中毒随后与血浆乳酸水平的升高同时出现。由于α-MSH水平未受到应激源的显著影响，而皮质醇水平增加了五到十倍，我们认为在真鲷受到急性应激后，血浆皮质醇的释放受促肾上腺皮质激素控制，可能还伴有交感神经刺激。
