Biomarker Responses in Piaractus mesopotamicus Following Oxytetracycline Treatment at Therapeutic Doses.

GRIBOFF J., CARRIZO J.C., BACCHETTA C., ROSSI A., CAZENAVE J., AMÉ M.V.

Montevideo

Congreso; Setac Latin America 15th Biennial Meeting; 2023

Antibiotics are commonly used in aquaculture, although their overuse or misuse can have negative effects on fish health. Oxytetracycline (OTC), is the principal member of the tetracycline group used in aquaculture worldwide, however, the ecotoxicological effects is still not fully understood. In this study, the pharmacological treatment of the freshwater fish Piaractus mesopotamicus with diets containing OTC pure (ATB1) and commercial form (ATB2) was carried out for 10 days with a withdrawal period of 21 days. After 0, 0.25, 3, 10, 11, and 31 days, alterations in morphological, hematological, plasma biochemical parameters and the enzymatic activity in different tissues (CAT, GST, APA, and LDH) were evaluated. The result showed that OTC did not generate morphological changes in individuals, but the fish fed with ATB2 suffered a decrease in hematocrit and an increase in glucose levels. In general, an increase in CAT activity is observed in the liver, gills and muscle of individuals treated with OTC, especially with ATB2. A similar trend was observed in the GST activity of the brain, gill and muscle. On the contrary, APA activity in the liver decreased in the groups fed with ATB1 and ATB2 when compared to the control. Moreover, only ATB2 induced LDH after 1-day depuration in fish muscle. Principal components analysis (PCA) revealed that most enzymes (except for FAL and GST in the liver), glucose, MCH and MCHC were associated with fish-fed ATB2. Conversely, hemoglobin, hematocrit, RBC, MCV, cholesterol, triglycerides, total protein, FAL and GST liver were associated with fish-fed ATB1 and the control group. These results demonstrated that the dietary therapeutic dose of OTC particularly that issued in commercial formulation caused adverse effects in P. mesopotamicus.