Yang Xiaozhen, Xu Minjie, Huang Genyong, Zhang Cong, Pang Yangyang, Yang Zhigang, Cheng Yongxu
Key Laboratory of Freshwater Aquatic Resources, Ministry of Agriculture, Shanghai Ocean University, Shanghai, China.
Shanghai Engineering Research Center of Aquaculture, National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China.
Front Physiol. 2018 Mar 21;9:270. doi: 10.3389/fphys.2018.00270. eCollection 2018.
Melatonin has been identified in a variety of invertebrate species, but its function is not as well understood as in crustaceans. The effects of melatonin on hemolymph glucose levels and tissue carbohydrate metabolism in the Chinese mitten crab, , were fully investigated in this study. Moreover, whether the eyestalk (an important endocrine center in invertebrate species) involves in this process or not, also were clarified. Analysis revealed that eyestalk ablation, especially bilateral, caused a significant decrease in the hemolymph glucose level. Moreover, injection of melatonin induced hyperglycemia in a dose-dependent manner both in intact and ablated crabs. Based on the expression of mRNA in the 10 different tissues, eyestalk, thoracic ganglion, intestinal tract and hemolymph were selected to estimate the effect of melatonin on the expression of mRNA. Bilateral eyestalk ablation caused a significant increase in the expression of mRNA in the thoracic ganglion, intestinal tract and hemolymph compared with the controls. In addition, injection of melatonin into intact or ablated crabs elevated the mRNA level in the eyestalk, thoracic ganglion and intestinal tract tissues compared with controls. The hemolymph mRNA after melatonin injection was elevated only in ablated crabs. Administration of melatonin resulted in a significant decrease in total carbohydrates and glycogen levels with an increase in phosphorylase activity levels in the hepatopancreas and muscle in intact and ablated crabs. Our findings demonstrated that melatonin can induce hyperglycemic effects in both intact and ablated crabs, suggesting that this effect is probably not mediated solely via eyestalk.
褪黑素已在多种无脊椎动物物种中被鉴定出来，但其功能不像在甲壳类动物中那样被人们所熟知。本研究全面调查了褪黑素对中华绒螯蟹血淋巴葡萄糖水平和组织碳水化合物代谢的影响。此外，还阐明了眼柄（无脊椎动物物种中的一个重要内分泌中心）是否参与这一过程。分析表明，眼柄切除，尤其是双侧切除，会导致血淋巴葡萄糖水平显著下降。此外，在完整和切除眼柄的螃蟹中，注射褪黑素均以剂量依赖的方式诱导高血糖。基于10种不同组织中mRNA的表达情况，选择眼柄、胸神经节、肠道和血淋巴来评估褪黑素对mRNA表达的影响。与对照组相比，双侧眼柄切除导致胸神经节、肠道和血淋巴中mRNA的表达显著增加。此外，与对照组相比，向完整或切除眼柄的螃蟹注射褪黑素可提高眼柄、胸神经节和肠道组织中的mRNA水平。褪黑素注射后血淋巴中的mRNA仅在切除眼柄的螃蟹中升高。在完整和切除眼柄的螃蟹中，施用褪黑素导致肝胰腺和肌肉中的总碳水化合物和糖原水平显著下降，同时磷酸化酶活性水平升高。我们的研究结果表明，褪黑素在完整和切除眼柄的螃蟹中均可诱导高血糖效应，这表明这种效应可能并非仅通过眼柄介导。
