氧化鱼油对黄颡鱼黑色素合成酶及内分泌激素的影响

实验模拟自然氧化条件制备氧化鱼油, 替代普通鱼油加入饲料中, 研究其对黄颡鱼(Pelteobagrus fulvidraco)表皮黑色素、酪氨酸酶活力、血清与脑内分泌激素含量的影响。处理组分别为未替代组(C组)、50%氧化鱼油替代组(Y50组)和100%氧化鱼油替代组(Y100组), 结果表明: 随着氧化鱼油替代普通鱼油的比例提高, 黄颡鱼5级(黑色素占细胞面积80%以上)黑色素细胞比例上升; 酪氨酸酶活力上升, 但各组差异不显著(P>0.05); 皮质酮(CORT)在血清和脑组织中各组含量差异均不显著(P>0.05); 肾上腺皮质激素(ACTH)在脑组织中含量增加 (P<0.05), 而血清中Y50组含量高于C组及Y100组(P<0.05); 血清中促肾上腺皮质激素释放激素(CRH)含量降低, Y50与Y100组之间差异不显著(P>0.05), 而脑组织中各组差异不显著(P>0.05); 血清中α-黑素细胞刺激素(α-MSH)含量, Y100组高于其他组(P<0.05), 而脑组织中各组差异不显著(P>0.05)。上述结果表明, 随着氧化鱼油替代普通鱼油的比例提高, 5级黑色素细胞比例上升, 黄颡鱼血清和脑组织中能互相转换的ACTH与α-MSH总量提高, 变化趋势与表皮黑色素含量和酪氨酸酶活性相一致。

EFFECTS OF DIETARY INCLUSION OF OXIDIZED FISH OIL ON MELANIN,MELANIN SYNTHETIC ENZYMES AND HORMONES OF PELTEOBAGRUS FULVIDRACO

We investigated the effects of fish feed containing oxidized fish oil on epidermal melanin expression, tyro-sinase activity, and hormone levels related to melanin synthesis in the serum and brain of Pelteobagrus fulvidraco. Fish oil was oxidized under natural conditions and substituted for normal fish oil in fish feed at concentrations of 100％(group Y100), 50％ (group Y50), and 0 (group C). Level 5 melanin cells, in which melanin accounts for >80％ of the cell area, increased in a dose-dependent manner with the amount of oxidized fish oil in the feed. There was a tendency for tyrosinase activity to increase with the amount of oxidized fish oil in the fish feed, but the increase was not statisti-cally significant. Brain tissue adreno-cortico-tropic hormone (ACTH) increased with the amount of oxidized oil in feed, while it only increased significantly in the serum of the Y50 group. Serum corticotropin releasing hormone decreased significantly in both the Y50 and 100 treatment groups but showed no significant changes in brain tissues. Similarly, serum α-melanocyte stimulating hormone (α-MSH) in group Y100 was significantly elevated, but no significant diffe-rences were detected in brain tissues. In contrast, serum and brain tissue corticosterone levels showed no significant dif-ferences among the three groups. These results suggest that oxidized fish oil in fish feed was positively related to the proportion of level 5 melanin cells and epidermal tyrosinase activity. Such changes were related to the increase in ACTH and α-MSH in P. fulvidraco.