Transient alterations in neuronal and behavioral activity following bensultap and fipronil treatment in rats.

In the present multilevel study, neuromodulatory effect of two insecticides, bensultap and fipronil were investigated in rats. Although the new generation of insecticides shows greater affinity to invertebrate as compared to mammalian receptors, toxic effect of these compounds in vertebrates cannot be excluded. The aim of the study was to follow the course of neuronal changes in rats for 1 week after a high-dose insecticide exposure. Alterations in synaptic excitability, in sleep-wake pattern and in behavior were analyzed using conventional in vitro brain slice method, long-lasting EEG recordings, and open-field tests. The two chemicals examined in this study induced only weak and transient effects. Bensultap, acting on nicotinic acetylcholine receptors, caused a transient decrease in neuronal excitability. Sleep and behavioral changes demonstrated a similar time course. Fipronil, on the other hand, increased excitability and its effect lasted slightly longer. All effects were greatest on the first day following 'poisoning', and measured variables usually returned to normal within a week. These results suggest that the studied compounds do have some effects on the mammalian nervous system, but this effect is usually mild and temporary.