饲料维生素C对美国红鱼(Sciaenops ocellatus)组织NO含量、NOS活力和nNOS基因表达的影响

EFFECTS OF DIETARY VITAMIN C ON NITRIC OXIDE, NITRIC OXIDE SYNTHASE ACTIVITY AND NITRIC OXIDE SYNTHASE GENE EXPRESSION IN TISSUE OF RED DRUM SCIAENOPS OCELLATUS

本试验旨在研究饲料维生素C对美国红鱼(Sciaenops ocellatus)组织中的NO含量、NOS活力和NOS基因表达的影响。采用单因子试验设计,将360尾平均体重为(147.28±7.69)g的美国红鱼随机分为6个处理,每个处理设3个重复,每个重复20尾,分别饲喂6种不同维生素C水平(0、49.3、98.9、197.5、396.4和1989.8mg/kg)的等氮等能饲料,进行为期8周的生长试验。结果表明:头肾、肝、肠、胸腺NO含量随着饲料维生素C含量增加有显著增加;脾中各组NO含量无显著性差异;脑中NO含量C0组与其它各组相比有显著性差异。头肾、肝、胸腺NOS活力随着饲料维生素C含量增加有显著增加;脾和肠中各组NOS活力无显著性差异;脑中NOS活力C396.4组与其它各组相比有显著性差异。脑中各组nNOS基因mRNA的表达含量无显著性差异;在饲料维生素C含量达到1989.8mg/kg时,其它各组织内的nNOS基因mRNA的表达量最高。综上所述,饲料中添加适当维生素C对美国红鱼组织中的NO含量、NOS活力和nNOS基因mRNA的表达有显著影响。

We conducted an experiment to study the effects of dietary vitamin A on nitric oxide, NOS activity and nNOS mRNA expression in tissues of red drum Sciaenops ocellatus. Six iso-nitrogenous and iso-energetic diets were formulated to contain graded level of vitamin C(0, 49.3, 98.9, 198.7, 398.6, and 1987.4 mg/kg diet, respectively) and fed to 18 floating net cages(1.5×1.0×1.0 m) each containing 20 fish(initial weight: 147g) twice daily(07:30, 16:30) for 8 weeks. Results indicate that after 8-week feeding trial, the levels of nitric oxide(NO) content and nitric oxide synthase(NOS) activity in head, kidney, liver, and thymus were boosted with increasing dietary vitamin C from 0 to 1987.4 mg/kg(P<0.05), but in spleen and intestines, no significant difference was found among dietary treatments. The NOS activity reached a peak value in brain fed at 398.6 mg/kg of dietary vitamin C. No significant difference in nNOS mRNA expression in brain was found among dietary treatments; the level of nNOS mRNA expression was found maximal in all tissues except for brain when fed 1987.4 mg/kg of dietary vitamin C. Therefore, adding dietary vitamin A in feed a proper amount could increase remarkably the NO content, NOS activity, and nNOS mRNA expression of red drum.