Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina.
Gen Comp Endocrinol. 2012 Mar 1;176(1):102-11. doi: 10.1016/j.ygcen.2012.01.002. Epub 2012 Jan 11.
Growth hormone (GH) is the main pituitary hormone involved in somatic growth. In fish, the neuroendocrine control of GH is multifactorial due to the interaction of multiple inhibitors and stimulators. Melanin-concentrating hormone (MCH) is a cyclic peptide involved in skin color regulation of fish. In addition, MCH has been related to the regulation of food intake in both mammals and fish. There is only one report presenting evidences on the GH release stimulation by MCH in mammals in experiments in vitro, but there are no data on non-mammals. In the present work, we report for the first time the sequence of MCH and GH cDNA in Cichlasoma dimerus, a freshwater South American cichlid fish. We detected contacts between MCH fibers and GH cells in the proximal pars distalis region of the pituitary gland by double label confocal immunofluorescence indicating a possible functional relationship. Besides, we found that MCH increased GH transcript levels and stimulated GH release in pituitary cultures. Additionally, C. dimerus exposed to a white background had a greater number of MCH neurons with a larger nuclear area and higher levels of MCH transcript than those fish exposed to a black background. Furthermore, fish reared for 3 months in a white background showed a greater body weight and total length compared to those from black background suggesting that MCH might be related to somatic growth in C. dimerus. Our results report for the first time, that MCH is involved in the regulation of the synthesis and release of GH in vitro in C. dimerus, and probably in the fish growth rate.
生长激素（GH）是参与躯体生长的主要垂体激素。在鱼类中，由于多种抑制剂和刺激物的相互作用，GH 的神经内分泌控制是多因素的。黑色素浓缩激素（MCH）是一种参与鱼类皮肤颜色调节的环状肽。此外，MCH 已被证明与哺乳动物和鱼类的食物摄入调节有关。仅有一份报告在体外实验中提出了 MCH 刺激哺乳动物 GH 释放的证据，但在非哺乳动物中没有数据。在本工作中，我们首次报道了淡水南美慈鲷 Cichlasoma dimerus 的 MCH 和 GH cDNA 序列。我们通过双标记共聚焦免疫荧光检测到垂体前叶近侧部的 MCH 纤维与 GH 细胞之间的接触，表明它们可能存在功能关系。此外，我们发现 MCH 增加了 GH 转录水平并刺激了 GH 的释放。此外，暴露在白色背景下的 C. dimerus 比暴露在黑色背景下的 C. dimerus 具有更多的 MCH 神经元，其核面积更大，MCH 转录水平更高。此外，在白色背景下饲养 3 个月的鱼比在黑色背景下饲养的鱼体重和全长更大，这表明 MCH 可能与 C. dimerus 的躯体生长有关。我们的研究结果首次报道了 MCH 参与了体外 C. dimerus 中 GH 的合成和释放的调节，并且可能与鱼类的生长速度有关。
