连续肌注恩诺沙星对中华草龟的急性和慢性毒理研究

为研究恩诺沙星对人工养殖中华草龟Chinemys reevesiis的药物毒性影响,在急性毒性试验中,将60只体质量约20 g的中华草龟随机分为6组,分别注射剂量为649.9、484.1、360.5、268.5、200.0、0(对照)mg/kg(体质量)的恩诺沙星,在慢性毒性试验中,将16只体质量约为100 g的中华草龟随机分为4组,分别注射剂量为0(对照)、10、30、50 mg/kg(体质量)的恩诺沙星,连续注射30 d,停药30 d,并在第0、2、13、28、40、50、60 d各抽取0.4 m L血液进行生化检测。结果表明:急性毒性试验中,观察两周后用Bliss法计算出半数致死浓度(LD50)为434.45 mg/kg,对死亡龟进行组织学检查显示,龟肝组织的肝细胞索结构混乱,有较严重淤血,大量嗜酸性粒细胞浸润,胃肠壁有水肿;慢性毒性试验中,注射过程中高剂量组(50 mg/kg)3只龟死亡,中剂量组(30 mg/kg)1只龟死亡,龟血清谷草转氨酶(AST)活性随时间呈先上升后下降的趋势,中剂量组显著高于低剂量组(10 mg/kg)和对照组(P0.05),在停止注射后,中、高剂量组总胆红素(T-bil)含量均迅速上升,剖检和组织学检查可见高剂量组肝脏密度减小,肝组织出现大小不一的空泡变性,肝小叶和肝细胞索无法辨识,肺组织结构混乱,胃肠道内有黄色黏稠液体,胃肠壁变薄、水肿,而肾组织无严重病变,注射部位肌肉出现较严重的水肿和炎症。研究表明,连续肌注恩诺沙星对中华草龟具有明显的肝毒性,且对肺、胃、肠道和肌肉组织也有一定的毒性,无肾毒性。

Acute and chronic toxicological effects of continuous intramuscular injection of enrofloxacin on Chinese pond turtle

Both acute and chronic toxic tests were conducted to evaluate the effects of continuous intramuscular in-jection of enrofloxacin on Chinese pond turtle Chinemys reevesiis. In the acute test, 60 individuals of 3-month-old Chinese pond turtle weighing around 20 g were randomly divided into 6 groups and injected with enrofloxacin at a dose of 649.9, 484.1, 360.5, 268.5, 200.0 mg/kg and 0( as control group) . In the chronic test, 16 individuals of Chinese pond turtle with body weight of 100 g were randomly divided into 4 groups and injected with enrofloxacin at a dose of 0(as control group), 10, 30, and 50 mg/kg for successive 30 days and for 30 days withdrawal. Blood samples of 0.4 mL were taken for blood biochemical tests 0, 2, 13, 28, 40, 50, and 60 days after administration. In two week acute test, the LD50 was estimated to be 434.45 mg/kg by the method of Bliss. The histopathological examination of the dead turtle in the highest dose group showed that the hepatic cell cords were disordered, severe congestion, massive eosinophil infiltration and edema in gastrointestinal wall. In the chronic toxic test, 3 turtles were all found to be dead in the maximal dose group and 1 turtle dead in 30 mg/kg dose group. Blood biochemical analysis revealed that activity of serum aspartate aminotransferase ( AST) was first increased and then decrease, significantly higher in 10 mg/kg group than in the control group ( P<0.05) . Total bilirubin( T-bil) levels were ele-vated rapidly at injection stopping time in the medium and high dose groups. The autopsy showed that the liver den-sity was decreased and suspended in the formalin in the middle and high dose groups, and that the yellow viscous liquid was found in the gastrointestinal tract in the high-dose group. The toxicological analysis in tissues demonstra-ted that continuous injection of high-dose enrofloxacin led to severe hepatic lesions in the liver of Chinese pond tur-tle, including vacuolar degeneration, and unidentified hepatic lobules and hepatocellular cords. The disorders of lung, thin wall and edema of the gastrointestinal tract were observed, without severe disorder in the renal tissue. Relatively severe edema and inflammation came out around the muscle injected. In conclusion, there is an obvious hepatotoxic effect of enrofloxacin, to some extend, toxicity in lung, and gastrointestinal tissue in area of injection, and no toxicity in the kidneys of Chinese pond turtle.