Institute of Cellular and Organismic Biology, Academica Sincia, Taipei, Taiwan, Republic of China.
J Endocrinol. 2020 Sep;246(3):277-288. doi: 10.1530/JOE-20-0053.
Timely adjustment of osmoregulation upon acute salinity stress is essential for the survival of euryhaline fish. This rapid response is thought to be tightly controlled by hormones; however, there are still questions unanswered. In this work, we tested the hypothesis that the endocrine hormone, insulin-like growth factor 1 (Igf1), a slow-acting hormone, is involved in the activation of salt secretion mechanisms in euryhaline medaka (Oryzias melastigma) during acclimation to acute salinity stress. In response to a 30-ppt seawater (SW) challenge, Na+/Cl- secretion was enhanced within 0.5 h, with concomitant organization of ionocyte multicellular complexes and without changes in expression of major transporters. Igf1 receptor inhibitors significantly impair the Na+/Cl- secretion and ionocyte multicellular complex responses without affecting transporter expression. Thus, Igf1 may activate salt secretion as part of the teleost response to acute salinity stress by exerting effects on transporter function and enhancing the formation of ionocyte multicellular complexes. These findings provide new insights into hormonal control of body fluid ionic/osmotic homeostasis during vertebrate evolution.
在急性盐度胁迫下，及时调整渗透调节对于广盐性鱼类的生存至关重要。这种快速反应被认为是由激素严格控制的；然而，仍有一些问题尚未得到解答。在这项工作中，我们检验了这样一个假设，即内分泌激素胰岛素样生长因子 1（Igf1）是一种作用缓慢的激素，它参与了广盐性红大麻哈鱼（Oryzias melastigma）在适应急性盐度胁迫时盐分泌机制的激活。在对 30 ppt 海水（SW）的挑战中，Na+/Cl-分泌在 0.5 小时内增强，伴随着离子细胞多细胞复合体的组织和主要转运体表达没有变化。Igf1 受体抑制剂显著损害了 Na+/Cl-分泌和离子细胞多细胞复合体的反应，而不影响转运体的表达。因此，Igf1 可能通过对转运体功能的影响和增强离子细胞多细胞复合体的形成来激活盐分泌，作为硬骨鱼对急性盐度胁迫反应的一部分。这些发现为脊椎动物进化过程中体液离子/渗透稳态的激素控制提供了新的见解。
