Toxic and histopathological effects induced by exposure to the pesticide dicamba in carp Cyprinus carpio L

This study investigated the effects of dicamba (DIC), a widely used auxinic pesticide in agriculture, on carp fish as an experimental model, especially examining serum adrenocorticotropic hormone (ACTH), cortisol (CORT), growth hormone (GH), and insulin-like growth factor-1 (IGF-1) levels. Additionally, it analyzed serum tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) levels, as well as histopathological changes in gill and liver tissues. Fish were exposed to varying doses (1.35 and 13.5 ppm) and durations (4 and 30 days). Sixty fish were randomly assigned to six groups (10 fish/group) and exposed to the specified DIC concentrations and durations. Following exposure, stress, growth, and immune parameters were assessed, along with pathological changes. Analyses revealed dose-dependent increases in ACTH, CORT, and TNF-α levels in both exposure periods compared to controls. Conversely, decreases in GH, IGF-1, IL-1β, and IL-6 levels were observed. A significant difference (p < 0.05) was noted in the changes of ACTH, CORT, TNF-α, GH, IGF-1, IL-1β, and IL-6 levels between the exposure periods in the subchronic phase for both dose groups. Histopathological examination identified significant alterations in gill and liver tissues across all dose groups. Gill pathology included epithelial separation (aneurysm), shortening and fusion of secondary lamellae, clubbing, reduced interlamellar space, and cartilage tissue damage. Liver histopathology showed hepatocellular degeneration, passive hyperemia, mononuclear cell infiltration, and hepatocyte vacuolization. In conclusion, dicamba exposure induced significant stress, growth, immune, and histopathological changes in carp, highlighting its potential harmful effects on aquatic organisms, especially at higher concentrations and prolonged exposure durations.