This study aimed to verify whether dietary quercetin protects against the detrimental effects induced by oxytetracycline (OTC) administration in silver catfish (Rhamdia quelen). Fish were divided into different experimental groups that received OTC and/or quercetin, either during 14 or 21 days. To determine the endocrine system stress response, we have measured the brain mRNA expression levels of corticotropin-releasing hormone (crh), proopiomelanocortins (pomca and pomcb) and some of the pituitary hormones (growth hormone [gh], somatolactin [sl], and prolactin [prl]). We have also quantified the levels of cortisol as well as some metabolites (glucose, glycogen, lactate, and triglycerides) in the plasma. Moreover, the enzymatic activity of hexokinase, phosphorylase (active GPase), fructose-biphosphatase (FBP), glycerol-3-phosphate dehydrogenase, glucose-6-phosphate dehydrogenase, and glutamate dehydrogenase (GDH) and gill Na⁺/K⁺-ATPase were measured. The results demonstrated that OTC activates the silver catfish stress response by increasing the plasma cortisol and decreasing the glucose levels at 14 and 21 days. Additionally, OTC also altered the fish hepatic metabolic status as demonstrated by an increase in triglycerides levels and the enzymatic activity of both FBP and GDH after 14 days. OTC also stimulated Na⁺/K⁺-ATPase activity in the gill after 14 days and altered the hypophyseal expression of gh (at 14 and 21 days) and prl (at 14 days). The co-treatment with 1.5 g of quercetin could prevent most of the alterations caused by OTC, strongly suggesting quercetin as a beneficial compound when added to the fish diet.

这项研究旨在验证饮食中的槲皮素是否可以防止由土霉素（OTC）引起的银cat鱼（Rhamdia quelen）的有害作用。将鱼分成在14或21天内接受OTC和/或槲皮素的不同实验组。为了确定内分泌系统的应激反应，我们测量了促肾上腺皮质激素释放激素（crh），促黑素皮层皮质激素（pomca和pomcb）和一些垂体激素（生长激素[ gh ]，生长抑素[ sl ]和催乳素[ prl ]）。我们还量化了血浆中皮质醇以及某些代谢物（葡萄糖，糖原，乳酸盐和甘油三酸酯）的水平。此外，己糖激酶，磷酸化酶（活性GPase），果糖双磷酸酶（FBP），甘油3-磷酸脱氢酶，葡萄糖-6-磷酸脱氢酶和谷氨酸脱氢酶（GDH）和ill Na ⁺ / K ⁺ -ATPase的酶活性。被测量。结果表明，OTC通过增加血浆皮质醇和降低14天和21天的葡萄糖水平来激活银the鱼的应激反应。此外，OTC还改变了鱼类的肝脏代谢状况，这在14天后甘油三酯水平增加以及FBP和GDH的酶促活性得到证实。场外交易也刺激钠14天后，in中的⁺ / K ⁺ -ATPase活性改变了gh（在14天和21天时）和prl（在14天时）的垂体后叶表达。与1.5 g槲皮素的共同治疗可以预防大多数由OTC引起的改变，强烈表明将槲皮素添加到鱼饲料中是有益的化合物。