Neurodevelopmental consequences of gestational exposure (GD14-GD20) to lowdose deltamethrin in rats

Effect of low level in utero exposure to deltamethrin (DT) (1 mg/kg wt.) du ring gestation day 14-20 was studied on selected neurobehavioral, neurochem ical, immunohistochemical parameters in rats at 6 and 12 weeks postnatal pe riod. The significant increase in acetylcholinesterase activity and decreas e in H-3-quinuclidinyl benzilate binding in the hippocampal region of DT ex posed animals, suggesting impairment in cholinergic (muscarinic) receptors. A significant decrease in the learning and memory performances was also ob served both at 6 and 12 weeks, which is directly correlated with decrease i n muscarinic receptor binding. Immunohistochemistry and image analysis of g rowth associated protein-43, a neuron specific protein present in axonal gr owth cone and a marker for neuronal differentiation and synaptogenesis, exh ibit aberrant increase in its expression in the hippocampus in DT exposed r ats at both time periods. The data suggests that low level exposure to DT i n utero during brain growth spurt period adversely affects the developing b rain and the changes persist even upto 12 weeks postnatal period in rats. A lthough there is no significant recovery at 12 weeks assessment but still s ignificant impairment persist on biochemical and behavioural parameters. (C ) 2001 Elsevier Science Ireland Ltd. All rights reserved.