Ramanzini Guilherme Corrêa, Volpato Gilson Luiz, Visconti Maria Aparecida
Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo,Rua do Matão, travessa 14, 101, CEP 05508-090, São Paulo, SP, Brazil.
Departamento de Fisiologia, Instituto de Biociências, Universidade Estadual Paulista Júlio de Mesquita Filho, CEP 8618-000, Postal Box 510, Botucatu, SP, Brazil.
Physiol Behav. 2018 Jan 1;183:33-38. doi: 10.1016/j.physbeh.2017.10.016. Epub 2017 Oct 19.
Body coloration has a fundamental role in animal communication by signaling sex, age, reproductive behavior, aggression, etc. Nile-tilapia exhibits dominance hierarchy and the dominants are paler than subordinates. During social interactions in these animals, these color changes occur rapidly, and normally the subordinates become dark. In teleosteans, from the great number of hormones and neurotransmitters involved in color changes, melanocyte hormone stimulates (α-MSH) and melanin concentrates hormone (MCH) are the most remarkable. The aim of this project was to investigate the role of MCH in the establishment of hierarchical dominance of the Nile-tilapia. We analyzed the effect of background coloration in the dominance hierarchy. It was then compared to the melanophore sensibility of dominants and subordinates' fishes to MCH; finally, it was checked if the social rank affects the number of these pigment cells in dominants and subordinated fishes. Fishes which have a social hierarchy established and adjusted individually to the background exhibits paler body coloration when a visual contact was possible, independently of previous social rank and background color. Probably, even recognizing each other, fishes could be defending their new territory. Melanophores of the subordinate fishes were more sensible to MCH than dominants. It suggests that dominants fishes, which are paler than subordinates, could be under a chronic effect of MCH, which could be due a desensitization of melanophores to this hormone. The opposite effect seems to be occurring on subordinate fishes. It was not observed a significant change in the number of melanophores when the fishes were exposed to a prolonged period of agonistic interaction. It is possible that the exposure time for this interaction might not have been sufficient to have any change in the number of these cells of dominants and subordinate fishes.
体色在动物交流中起着基础性作用，可用于表明性别、年龄、繁殖行为、攻击性等。尼罗罗非鱼呈现出等级制度，占主导地位的个体比从属个体颜色更浅。在这些动物的社交互动过程中，体色变化迅速，通常从属个体会变黑。在硬骨鱼类中，参与体色变化的激素和神经递质种类繁多，其中黑素细胞刺激激素（α-MSH）和黑色素浓缩激素（MCH）最为显著。本项目的目的是研究MCH在尼罗罗非鱼等级优势确立过程中的作用。我们分析了背景颜色在等级制度中的影响。然后将其与占主导地位和从属地位的鱼类对MCH的黑素细胞敏感性进行比较；最后，检查社会等级是否会影响占主导地位和从属地位的鱼类中这些色素细胞的数量。已建立社会等级并根据背景单独调整的鱼类，在有视觉接触时，无论其先前的社会等级和背景颜色如何，都会呈现出较浅的体色。可能即使鱼类相互识别，它们也在保卫自己的新领地。从属鱼类的黑素细胞对MCH比占主导地位的鱼类更敏感。这表明，比从属鱼类颜色更浅的占主导地位的鱼类可能长期受到MCH的影响，这可能是由于黑素细胞对这种激素脱敏所致。从属鱼类似乎出现了相反的效果。当鱼类长时间处于争斗互动中时，未观察到黑素细胞数量有显著变化。有可能这种互动的暴露时间不足以使占主导地位和从属地位的鱼类的这些细胞数量发生任何变化。
