Toxicity assessement of chlorpyrifos in red-bellied pacu fingerlings (Piaractus brachypomus

Background and Aim: Organophosphate pesticides (OPs) used in agricultural production pose environmental and public health risks whenever non-target organisms are exposed to them. Oxon-type OPs, such as trichlorfon (TCF) and chlorpyrifos (CPF), are frequently used in Colombia and have been detected in water bodies in the vicinity of croplands; however, their effect on aquatic organisms, especially fish, is largely unknown. The neurotoxicity of OPs includes inhibition of esterase enzymes, neuronal damage, and increased glial reactivity. This study aimed to assess the astrocytic response in the brain tissue of juvenile red-bellied pacu (Piaractus brachypomus) exposed to TCF and CPF. Materials and Methods: A 25-day subchronic assay was conducted in which juvenile red-bellied pacu were exposed to CPF and TCF. After 25 days of exposure, the fish were killed and brain samples were collected and processed for immunohistochemistry to assess the morphology and reactivity of astrocytes; glial acidic fibrillary protein was used as a biomarker. Results: The brain samples from animals under subchronic exposure to OPs for 25 days showed higher cellular density as well as changes in astrocyte phenotype characterized by shortening of cytoplasmic projections, hypertrophy, and ameboid morphology compared to those from nonexposed animals. Similarly, astrocyte hyperreactivity was detected in the optic tectum and medial longitudinal fasciculus of the exposed group. Conclusion: Immunoreactivity of brain glial cells under subchronic exposure to OPs measured through immunohistochemical tests as well as OPs-induced neuropathology may be useful as a biomarker for monitoring environmental pollution. The results also indicate that P. brachypomus is a suitable biomonitoring model for studying neurotoxicological and neurodegenerative diseases.

El objetivo del estudio fue determinar el grado de resistencia antihelmíntica de nematodos que afectan las producciones ovinas del valle cálido del Alto Magdalena en el departamento del Tolima, Colombia, mediante la técnica de reducción de conteo de huevos en materia fecal. El estudio se realizó con 380 ovinos en 13 predios. Se determinó la carga de parásitos gastrointestinales mediante la técnica de McMaster. Ovinos con >200 huevos por gramo de heces fueron distribuidos aleatoriamente en cuatro grupos de antihelmínticos (fenbendazol, moxidectina, ivermectina y levamisol) y un grupo control. Se colectaron muestras en el día 0 y en el día 14 pos-dosificación para determinar el porcentaje de efectividad del fármaco. Además, se realizaron cultivos de larvas para determinar las especies de nematodos presentes. Se encontró resistencia antihelmíntica, especialmente a Haemonchus spp en el 91, 89 y 46% de los predios hacia fenbendazol, ivermectina y levamisol, respectivamente, compuestos de mayor uso en la región, así como multiresistencia en el 78% de los predios.