Dose-Dependent Toxicity of Pyriproxyfen in Common Carp (Cyprinus carpio): Hematological, Biochemical, Genotoxic, and Molecular Responses

Abstract

This study evaluated both the acute and sublethal effects of pyriproxyfen in Cyprinus carpio using an integrated multibiomarker approach. The 96-h LC50 value was calculated as 4.525 mg/L. Following 14 days of sublethal exposure, pyriproxyfen caused clear, dose-dependent changes across hematological, biochemical, genotoxic, and molecular parameters. Hemoglobin and hematocrit levels declined progressively with increasing concentration, pointing to the development of anemia-like conditions. Biochemical analyses revealed a biphasic response pattern: Several parameters initially increased at lower concentrations but declined at higher doses, suggesting a shift from adaptive metabolic responses to hepatic impairment. DNA damage, assessed by the comet assay, increased significantly in all exposed groups, indicating genotoxic effects even at relatively low concentrations. At the molecular level, antioxidant and proinflammatory genes were upregulated at low to moderate doses, reflecting an early defense response. However, their expression was suppressed at higher concentrations, implying exhaustion of protective mechanisms. In contrast, HSP70 expression increased steadily with dose, highlighting the intensification of cellular stress and protein damage. Overall, the findings demonstrate that pyriproxyfen exposure triggers an initial adaptive response that progressively transitions into physiological dysfunction at higher concentrations, underscoring its potential ecological risk to aquatic organisms.