Kelsall C J, Balment R J
School of Biological Sciences, University of Manchester, G.38 Stopford Building, Manchester, M13 9PT, United Kingdom.
Gen Comp Endocrinol. 1998 Nov;112(2):210-9. doi: 10.1006/gcen.1998.7166.
Adrenocorticotrophic hormone (ACTH) and flounder urotensins I and II (UI and UII) stimulate cortisol secretion of isolated interrenal/head kidney preparations of seawater (SW)-adapted flounder. UI and UII at concentrations of 10(-6) and 10(-7) M, respectively, increased cortisol secretion when acting on SW-derived interrenal but did not affect cortisol secretion in tissue derived from freshwater (FW) fish. Combined UI and UII had no synergistic or additive steroidogenic action, but either 10(-7) M UI or 10(-7) M UII in combination with ACTH produced a very marked, additive, or synergistic steroidogenic response, most apparent on interrenal derived from FW fish. These results suggest that urotensins enhance the steroidogenic action of ACTH in flounder. In all cases, significant steroidogenesis was apparent within 1 h postperifusion of ligands. In SW-adapted flounder intraarterial infusion of UII in vivo caused a concentration-dependent increase in plasma cortisol concentration within 1 h after infusion, while after 5 x 10(-6) M UI infusion a similar trend was evident but this did not achieve statistical significance. The data suggest that the caudal neurosecretory system may control interrenal cortisol secretion, to modulate cortisol secretion independently of the hypophysial axis, perhaps in response to specific stress-induced or osmoregulatory challenge.
促肾上腺皮质激素（ACTH）以及比目鱼泌尿紧张素I和II（UI和UII）可刺激海水适应比目鱼离体肾上腺/头肾组织分泌皮质醇。UI和UII浓度分别为10^(-6) M和10^(-7) M时，作用于海水来源的肾上腺可增加皮质醇分泌，但对淡水鱼来源的组织中的皮质醇分泌无影响。联合使用UI和UII没有协同或相加的类固醇生成作用，但10^(-7) M的UI或10^(-7) M的UII与ACTH联合使用时，会产生非常明显的相加或协同类固醇生成反应，在淡水鱼来源的肾上腺上最为明显。这些结果表明，泌尿紧张素可增强比目鱼中ACTH的类固醇生成作用。在所有情况下，配体灌注后1小时内类固醇生成明显。在海水适应的比目鱼中，体内动脉内注入UII会在注入后1小时内导致血浆皮质醇浓度呈浓度依赖性增加，而注入5×10^(-6) M的UI后也有类似趋势，但未达到统计学显著性。数据表明，尾神经分泌系统可能控制肾上腺皮质醇分泌，以独立于垂体轴调节皮质醇分泌，这可能是对特定应激诱导或渗透调节挑战的反应。
