Fisheries Faculty, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran.
Fish Physiol Biochem. 2010 Dec;36(4):1061-7. doi: 10.1007/s10695-010-9383-x. Epub 2010 Feb 11.
Common carp juveniles were fed two types of diet (control: 0.1% tryptophan and TRP: 0.6% tryptophan) over 15 days. Thereafter, both groups were directly subjected to osmotic challenge (from 0 to 10 ppt) for 168 h. Blood samples were collected at -240, 0, 6, 24, 72 and 168 h after challenge. Survival and serum cortisol, glucose, sodium and chloride levels were measured to determine stress response and osmoregulation condition. While TRP group showed no mortality until 168 h, cumulative mortality was near 100% at 72 h after challenge in control group. Feeding tryptophan-supplemented diet led to increase in prechallenge cortisol, but not glucose, sodium and chloride values at -240 h that stayed elevated until 0 h after challenge. After challenge, cortisol and glucose values did not significantly affected by time of sampling but type of diet and diet×time interaction. Sodium values significantly affected by diet type and time of sampling but not their interaction. Chloride values significantly affected by time of sampling but not diet type and their interaction. Control group had higher cortisol, glucose and sodium than TRP at each time of sampling. Control and TRP group showed increasing and decreasing pattern in cortisol and glucose values when experiment progressed after osmotic challenge. Both group showed increasing pattern in sodium and chloride values when experiment progressed after osmotic challenge. Results indicated that tryptophan supplementation enhanced salt water tolerance of carp that is due to increase in basal cortisol and anti-stress effect of tryptophan and possibly increase in serotonergic activity.
鲤鱼幼鱼在 15 天内分别投喂两种饲料（对照组：0.1%色氨酸；TRP 组：0.6%色氨酸）。此后，两组幼鱼直接进行渗透压挑战（从 0 到 10 ppt），持续 168 小时。在挑战后-240、0、6、24、72 和 168 小时采集血样。测量存活情况和血清皮质醇、葡萄糖、钠和氯水平，以确定应激反应和渗透调节情况。TRP 组在 168 小时内没有出现死亡率，而对照组在挑战后 72 小时内的累积死亡率接近 100%。投喂色氨酸补充饲料会导致挑战前的皮质醇升高，但不会导致葡萄糖、钠和氯升高，这种情况一直持续到挑战后 0 小时。挑战后，皮质醇和葡萄糖值不受采样时间的影响，但受饲料类型和饲料×时间的交互作用影响。钠值受饲料类型和采样时间的影响，但不受其交互作用的影响。氯值仅受采样时间的影响，但不受饲料类型和其交互作用的影响。对照组在每个采样时间的皮质醇、葡萄糖和钠值都高于 TRP 组。在渗透压挑战后，对照组和 TRP 组的皮质醇和葡萄糖值呈先升后降的模式。两组的钠和氯值在渗透压挑战后均呈先升后降的模式。结果表明，色氨酸补充增强了鲤鱼的耐盐能力，这可能是由于基础皮质醇升高和色氨酸的抗应激作用，以及可能的 5-羟色胺能活性增强。
