Aspectos fisiopatológicos do pesticida Maxsan® em modelo experimental de zebrafish

Resumo (EN)

This study began with a literature review of pesticides recently approved for use in Brazil, which resulted in the publication of a scientific article (DOI: 10.62516/terra_livre.2025.3803). A record number of newly licensed pesticides were identified, many of which are potentially harmful to the environment and public health. Next, the pesticide Maxsan® (dinotefuran + pyriproxyfen, 100 + 25 g/L) was selected for the experimental phase of the study, based on predefined inclusion and exclusion criteria, using zebrafish as the model organism. Zebrafish were exposed to three concentrations of Maxsan® (0.00001, 0.0001, and 0.0002 mL/L) for eight days. Daily assessments included spatial distribution in the tanks, alarm reactions, general health aspects, and survival rate. On the final day, individual behavior in a novel tank, body weight, sex, histopathological alterations in the gills and liver, immunohistochemical detection of glial fibrillary acidic protein (GFAP) in astrocytes, and the gene expression (RT-qPCR) of brain biomarkers were analyzed. Compared with the control group, Maxsan® exposure: (1) shifted daily basal spatial distribution toward the water surface; (2) induced transient lethargy; (3) caused substantial lethality; (4) triggered erratic movements; (5) produced marked histopathological damage in the gills; (6) caused liver injury; (7) induced astrogliosis in the brain; and (8) altered gene expression, including downregulation of antioxidant enzymes (sod and gpx), upregulation of hypoxia-related genes (ngb and hif1a), and reduced bdnf expression. Overall, Maxsan® appears to affect zebrafish by inducing degenerative gill alterations that lead to hypoxia and increased surface dwelling. This, in turn, resulted in liver toxicity, neuroinflammatory responses, and oxidative stress, ultimately reducing BDNF synthesis. These alterations collectively impaired behavior, leading to erratic movements and lethargy. In conclusion, this study investigated pathophysiological impacts of environmentally relevant concentrations of Maxsan® in a zebrafish model. The findings underscore the need for federal authorities to reassess the approval of this pesticide for agricultural use.