Changes in plasma prolactin and growth hormone concentrations during freshwater adaptation of juvenile chum salmon (Oncorhynchus keta) reared in seawater for a prolonged period
Changes in plasma prolactin and growth hormone concentrations during freshwater adaptation of juvenile chum salmon (Oncorhynchus keta) reared in seawater for a prolonged period
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长期在海水中饲养的幼鲑鱼（Oncorhynchus keta）淡水适应过程中血浆催乳素和生长激素浓度的变化
DOI：
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发表时间：
1989
影响因子：
2.9
通讯作者：
M. Tagawa
中科院分区：
文献类型：
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作者：
T. Ogasawara;T. Hirano;T. Akiyama;S. Arai;M. Tagawa
以海水养殖4个月的大麻哈鱼幼鱼为对象，研究大麻哈鱼的淡水适应性。这些重约40克的鱼于10月被直接转移到淡水中，当时它们的同伴正在北太平洋迁徙。血浆钠浓度从海水中的167 mM下降到约130 mM，在第一个24小时，并逐渐增加，在2-7天后转移。没有免疫反应性催乳素（PRL）检测到的血浆中的海水适应的鱼，也没有在第一个24小时在淡水。2-3天后检测到显著水平的PRL。5天后观察到最大水平（2.6 ng/ml），7天后再次检测不到;转移期间血浆钠和PRL水平变化之间无显著相关性。血浆生长激素水平相对恒定，除了在转移后12小时显著下降。虽然血浆甲状腺素水平在实验过程中变化很大，但在转移后12小时和5天分别观察到显著下降和上升。目前的研究表明，少年鲑鱼保留hyperplasia调节能力，即使在海水中长时间饲养。周转率的检查，而不是血浆水平的变化，似乎是必要的，以澄清激素的调节作用。
Freshwater adaptability of chum salmon was examined in juvenile fish reared in seawater for 4 months. The fish, weighing about 40g, were transferred directly to fresh water in October, when their cohorts are migrating in the North Pacific Ocean. Plasma sodium concentration decreased from 167 mM in seawater to about 130 mM during the first 24h, and increased gradually during 2–7 days after the transfer. No immunoreactive prolactin (PRL) was detected in the plasma of the seawater-adapted fish nor during the first 24h in fresh water. Significant levels of PRL were detected after 2–3 days. The maximal level (2.6 ng/ml) was observed after 5 days and became undetectable again after 7 days; no significant correlation was seen between the changes in plasma sodium and PRL levels during the transfer. Plasma growth hormone levels were relatively constant, except for a significant decrease 12h after the transfer. Although plasma thyroxine levels were highly variable during the experiment, a significant decrease and an increase were observed 12h and 5 days after the transfer, respectively. The present study indicates that juvenile chum salmon retain hyperosmoregulatory ability even after prolonged rearing in seawater. Examination of turnover rates, rather than changes in plasma levels, seems to be essential to clarify the osmoregulatory roles of the hormones.