Alpha-melanocyte-stimulating hormone (α-MSH), a peptide derived from proopiomelanocortin (POMC), and melanin-concentrating hormone (MCH), act as neuromodulators and regulate food intake in vertebrates. In teleosts, these peptides are also involved competitively in body color regulation; α-MSH induces a dark body color, while MCH induces a pale body color. Similarly, members of the growth hormone (GH) family, somatolactin (SL) and prolactin (PRL), which are involved in the regulation of energy metabolism, are also associated with body color regulation in teleosts. Since these hormones are involved in both body color regulation and energy metabolism, it is possible that feeding status can affect body color. Here, we examined the effects of fasting on the response of goldfish body coloration to changes in background color. Goldfish were acclimated for one week in tanks with a white or black background under conditions of periodic feeding or fasting. The results showed that body color and expression levels of pmch1 and pomc were affected by background color, irrespective of feeding status. Expression levels of sla were higher in fish maintained in tanks with a black background than in tanks with a white background, and higher in the fasted fish compared to the fed fish. However, the pattern of slb expression was almost the opposite of that observed in sla expression. The expression levels of gh and prl in the pituitary, and pmch2a and pmch2b in the brain, were not affected by background color. These results suggest that MCH, α-MSH, SLα, and SLβ might be involved in body color regulation and that they are affected by background color in goldfish. The results also suggest that feeding status may affect body color regulation via SLα and SLβ, although these effects might be limited compared to the effect of background color.

α-黑色素细胞刺激素 (α-MSH) 是一种源自阿片黑皮质素原 (POMC) 和黑色素浓缩激素 (MCH) 的肽，可作为神经调节剂并调节脊椎动物的食物摄入。在硬骨鱼中，这些肽也竞争性地参与体色调节。α-MSH 诱导深色体色，而 MCH 诱导浅色体色。同样，参与能量代谢调节的生长激素 (GH) 家族成员生长乳素 (SL) 和催乳素 (PRL) 也与硬骨鱼的体色调节有关。由于这些激素参与体色调节和能量代谢，因此进食状态可能会影响体色。在这里，我们检查了禁食对金鱼身体颜色对背景颜色变化的反应的影响。金鱼在定期喂食或禁食的条件下，在白色或黑色背景的水箱中适应一周。结果表明，体色和表达水平pmch1和pomc受背景颜色的影响，与喂养状态无关。sla在黑色背景鱼缸中的表达水平高于白色背景鱼缸中的表达水平，并且与喂食的鱼相比，禁食鱼中的表达水平更高。然而，slb表达的模式几乎与在sla表达中观察到的相反。垂体中gh和prl以及pmch2a和pmch2b的表达水平在大脑中，不受背景颜色的影响。这些结果表明 MCH、α-MSH、SLα 和 SLβ 可能参与体色调节，并且它们受金鱼背景颜色的影响。结果还表明，摄食状态可能通过 SLα 和 SLβ 影响体色调节，尽管与背景颜色的影响相比，这些影响可能是有限的。