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Made available in DSpace on 2021-06-25T10:47:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-12-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Empresa Brasileira de Pesquisa Agropecuária Antibiotics, Hematological Variables, Oxidative stress, Aquaculture; Agricultural Water Management; Environmental Science; Environmental Risk Assessment; Environmental Toxicology; Toxicology Intensive fish cultivation has a high incidence of infection, which is often controlled by administering antibiotics. Florfenicol (FF) is one of the two antimicrobial drugs permitted for aquaculture in Brazil. Due to their intensive use, potentially harmful effects on aquatic organisms are of great concern. In this sense, we investigated whether the presence of FF in cultivation water could change the health parameters of Nile tilapia. For this, we evaluated hemoglobin, hematocrit, mean corpuscular hemoglobin (MCHC) concentration, mean corpuscular volume (MCV), total plasma protein (TPP), number of circulating red blood cells and leukocytes, as lipid peroxidation levels, catalase activity and glutathione S-transferase activity of fish exposed to 11.72 mg L−1 of FF in water for 48 h. The fish were divided into two groups: Nile tilapia in water with FF or without FF (control). Exposure to FF in cultivation water for a short period didn't change the hematological variables analyzed, but caused changes in liver ROS (Reactive oxygen species) markers of the Nile tilapia, which was revealed by lipid peroxidation levels, catalase activity, and glutathione S-transferase. The 48h exposure period was enough to induce oxidative stress in hepatocytes, causing cellular oxidative damage. Therefore, the antibiotic florfenicol may cause toxicity to organisms and aquatic ecosystems, even at a sublethal concentrations near 1/100 LC50-48h for fish species. Institute of Chemistry University of Campinas, POB 6154 Joint Graduate Program in Physiological Sciences Federal University of São Carlos -UFSCar/São Paulo State University UNESP Campus Araraquara Embrapa Environment Brazilian Agricultural Research Corporation (EMBRAPA), Rod. SP 340, Km 127,5, Caixa Postal 69 Joint Graduate Program in Physiological Sciences Federal University of São Carlos -UFSCar/São Paulo State University UNESP Campus Araraquara Empresa Brasileira de Pesquisa Agropecuária: 0117020010606007

Trichlorfon [TCF] is an organophosphate compound used to eliminate or control a variety of parasites in farmed fish. The physiological and biochemical responses of juvenile Nile tilapia were studied after 96 hours of exposure to TCF. The experiment was conducted randomly with two treatments: control and TCF (0.5 mg L-1). No mortality or changes in hematological profile were recorded for the fish. On the other hand, we found that TCF exposure caused behavioral, metabolic and hormonal changes that modified the response patterns of the immune and enzymatic defense system in muscle and liver tissues. Increased plasma cortisol and glucose combined with the reduction of acetylcholinesterase activity in muscle and liver tissue after 96-h of TCF exposure indicates chemical stress. In response to this harmful situation, we observed changes in the immune system that lead to an increased number of leukocytes, thrombocytes, monocytes, lysozyme and leukocyte respiratory burst activity. Furthermore, we associate the increased activity of glutathione-S-transferase in liver tissue as a strategy fish use to combat the effects of TCF. Thus, we conclude that TCF affects the physiologic parameters of Nile tilapia, which can generate irreversible situations of recovery of the clinical condition. Such fact highlights the need to search for new compounds that could replace TCF, that have no or few adverse effects on fish species. Made available in DSpace on 2021-02-02T01:07:36Z (GMT). No. of bitstreams: 1 Ishikawa-Physiological-biochemical-2020.pdf: 411152 bytes, checksum: 3055487f2054433a3537fc309c715a16 (MD5) Previous issue date: 2020