Adverse developmental and behavioral effects of imidacloprid in mice

The study aimed to explore the acute toxic effects of the broad-spectrum imidacloprid (IMI) insecticide in adult mice and their adverse impact on the development and neurobehavioral levels in postnatal pups exposed to it during the pregnancy period. This goal was supported by brain histological sections from exposed newborn pups. The oral LD50 doses of IMI were 113.15 and 107.2 mg/kg in female and male mice, respectively. The mice treated with toxic percentages 60 and 80% of acute oral LD50 suffered from salivation, nasal discharge, lacrimation, lethargy, piloerection, tremor, straub tail, and convulsions. The doses of 90.5 and 85.5 mg/kg produced a significantly higher toxic ratio with 100% death compared to lower doses 68 and 64 mg/kg, respectively. Exposure of the pregnant mice to IMI at 11 and 34 mg/kg orally during the 7th to 15th days of pregnancy produced developmental defects in newborn pups as a significant delay in pinna opening, lint growth, and eye-opening compared to control. The postnatal pups also suffered from neurobehavioral toxic effects as significant delays in both righting reflex time on postnatal day (PND)5 and cliff avoidance performance on PND 6 compared to control; the same doses also produced significant lowering in the scores of olfactory discriminations on PND 9 and swimming test on PND 10 compared to control. The histological changes in the newborn brain from exposure dams show vacuolization in the cortex of the cerebrum, periaxonal edema, neurophagia, glial cell satellitosis, and gliosis. The data in the current study concluded that there were toxic effects of IMI in adult mice models, and exposure to IMI during pregnancy, even in low doses, produced developmental and behavioral defects in newborns from exposure mothers.