Hepatic and blood alterations in Lithobates catesbeianus tadpoles exposed to sulfamethoxazole and oxytetracycline

• Published in: Chemosphere (Oxford) Vol. 307; p. 136215
• Main Authors: Rutkoski, Camila Fatima, Grott, Suelen Cristina, Israel, Nicole Grasmuk, Carneiro, Francisco Estevão, de Campos Guerreiro, Fernando, Santos, Sabrina, Horn, Priscila Aparecida, Trentini, Amanda Alves, Barbosa da Silva, Elizia, Coelho de Albuquerque, Claudia Almeida, Alves, Thiago Caique, Alves de Almeida, Eduardo
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2022
• Subjects: Antibiotics; Tadpoles; Toxicity; Veterinary drugs; Antibiotics; Veterinary drugs; Toxicity; Tadpoles
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2022.136215

In this study the effects of environmentally realistic concentrations of the antibiotics sulfamethoxazole (SMX) and oxytetracyclyne (OTC) on Lithobates catesbeianus tadpoles were evaluated, through the analyzes of the frequencies of micronucleus and nuclear abnormalities in erythrocytes, alterations in leucocytes, liver histopathology, and changes in hepatic esterase activities and oxidative stress biomarkers. The animals were exposed for 16 days at concentrations of 0 (control), 20, 90 and 460 ng L−1. No significant difference was found in the frequencies of micronucleus and nuclear abnormalities. The two highest concentrations of SMX and all concentrations of OTC caused a significant increase in the number of lymphocytes. A significant decrease in the number of neutrophils compared to the control group was observed for all concentrations tested of both antibiotics. Also, decrease in the activity of glutathione S-transferase and high histopathological severity scores, indicating liver damage, were found in tadpoles exposed to the two highest concentrations of SMX and all concentrations of OTC. The main changes in the liver histopathology were the presence of inflammatory infiltrate, melanomacrophages, vascular congestion, blood cells and eosinophils. Esterase activities were unchanged. Indeed, the two highest concentrations of OTC caused a reduction in the activities of superoxide dismutase and glucose 6-phosphate dehydrogenase, while the highest concentration inhibited the activity of glutathione peroxidase and increased protein carbonyl levels. These results evidences that environmentally realistic concentrations of SMX and OTC in aquatic environments are capable to significantly disrupt tadpoles’ physiology, possibly affecting negatively their survival rate in natural environments. [Display omitted] •Hepatic and blood effects of sulfamethoxazole and oxytetracycline were evaluated in tadpoles.•Sulfamethoxazole and oxytetracycline caused neutropenia and lymphocytosis in tadpoles.•Sulfamethoxazole and oxytetracycline caused hepatocellular damages to tadpole.•Oxytetracycline reduced antioxidant defenses and increased protein carbonyl levels.