Organophosphate pesticides induce morphological abnormalities and decrease locomotor activity and heart rate in Danio...

Area of Science:

• Environmental toxicology
• Ecotoxicology of pesticides
• Vertebrate developmental studies

Background:

• Organophosphate pesticides (OPs) are widely used agricultural chemicals.
• OPs inhibit acetylcholinesterase, posing risks to non-target species due to conserved enzyme function.
• Aquatic vertebrates like zebrafish and Xenopus are susceptible to OP toxicity.

Purpose of the Study:

• To investigate the morphological and physiological effects of developmental exposure to three common OPs (chlorpyrifos, dichlorvos, diazinon).
• To compare the differential toxicity of these OPs on two aquatic vertebrate models: Danio rerio (zebrafish) and Xenopus laevis.
• To establish a baseline for ecotoxicological evaluation using standardized protocols and multiple species.

Main Methods:

• Zebrafish and Xenopus were exposed to varying concentrations (0–1000 µM) of chlorpyrifos, dichlorvos, and diazinon under uniform conditions.
• Observed endpoints included survival, locomotor activity, heart rate, and gross anatomical abnormalities over a 5-day period.
• Specific abnormalities monitored were kyphosis and edema.

Main Results:

• Decreased survival was observed for all three OPs at higher concentrations in both species.
• Xenopus exhibited higher mortality than zebrafish at lower concentrations of chlorpyrifos and dichlorvos.
• Chlorpyrifos and dichlorvos caused dose-dependent reductions in heart rate and larval activity; chlorpyrifos and dichlorvos induced kyphosis and spinal deformities in Xenopus.
• Diazinon did not affect motor activity but caused cardiac edema in zebrafish.

Conclusions:

• Developmental exposure to OPs causes significant adverse effects in aquatic vertebrates, including mortality, reduced activity, and morphological deformities.
• Differential susceptibility between zebrafish and Xenopus highlights the importance of using multiple models for comprehensive ecotoxicological risk assessment.
• Standardized protocols are crucial for accurately evaluating the ecotoxicological impacts of pesticides like OPs.