Hosoya S, Johnson S C, Iwama G K, Gamperl A K, Afonso L O B
Institute for Marine Biosciences (IMB), National Research Council of Canada (NRC), 1411 Oxford St., Halifax, NS., Canada B3H 3Z1.
Comp Biochem Physiol A Mol Integr Physiol. 2007 Jan;146(1):78-86. doi: 10.1016/j.cbpa.2006.09.003. Epub 2006 Sep 15.
We measured changes in free and total plasma cortisol levels, plasma glucose, gill hsp70 levels, and growth in haddock (Melanogrammus aeglefinus) subjected to a long-term handling stress (15 s out of water, each day, for 4 weeks), and the effect of this long-term stress on the ability of haddock to respond to an acute stressor. The acute stressor was a single handling stress, and fish were sampled at 1, 6, and 12 h post-stress. During the long-term stress study, free and total plasma cortisol levels increased significantly (10-fold) in the stressed group after the second week. However, the percentage of free cortisol was already significantly elevated by the first week (control 17%, stressed 55%), and remained high during the second week (control 35% and stressed 65%). After 3 and 4 weeks of handling, both free and total cortisol declined in stressed fish to levels that were not significantly different from pre-stress values. Control fish grew significantly more than stressed fish (by 32% and 18%, respectively) over the 4 week study, and condition factor only increased in control fish. Although fish from the control group showed elevated total plasma cortisol levels (to 47 ng mL(-1)) 1 h after the acute stress, and the levels in stressed fish were comparable to those for the control fish, no significant increase in plasma cortisol was measured in the group subjected to the long-term stress. Free plasma cortisol levels did not increase significantly in either group following the acute stress. However, free plasma cortisol levels were significantly higher in long-term stress group, as compared with the control group, at 6 h post-stress. Plasma glucose and gill hsp70 levels were not altered by either the long-term stress or acute stressor. Our data indicate that cortisol (free and total), but not glucose or hsp70, appears to be adequate to assess short- and long-term stress in haddock.
我们测量了长期处理应激（每天离水15秒，持续4周）的黑线鳕（Melanogrammus aeglefinus）的游离和总血浆皮质醇水平、血浆葡萄糖、鳃hsp70水平以及生长情况，以及这种长期应激对黑线鳕应对急性应激源能力的影响。急性应激源为单次处理应激，在应激后1、6和12小时对鱼进行采样。在长期应激研究中，应激组的游离和总血浆皮质醇水平在第二周后显著升高（10倍）。然而，游离皮质醇的百分比在第一周就已显著升高（对照组17%，应激组55%），并在第二周保持高位（对照组35%，应激组65%）。经过3周和4周的处理，应激鱼的游离和总皮质醇均下降至与应激前值无显著差异的水平。在为期4周的研究中，对照鱼的生长显著快于应激鱼（分别快32%和18%），且仅对照鱼的条件系数增加。虽然对照组的鱼在急性应激后1小时总血浆皮质醇水平升高至47 ng mL(-1)，且应激鱼的水平与对照鱼相当，但长期应激组未检测到血浆皮质醇的显著增加。急性应激后两组的游离血浆皮质醇水平均未显著升高。然而，在应激后6小时，长期应激组的游离血浆皮质醇水平显著高于对照组。长期应激或急性应激源均未改变血浆葡萄糖和鳃hsp70水平。我们的数据表明，皮质醇（游离和总）而非葡萄糖或hsp70似乎足以评估黑线鳕的短期和长期应激。
