Distribution and Significance of Nitric Oxide Synthase in Brain Tissues of Rats Exposed to Deltamethrin Insecticide

The distribution of nitric oxide synthase (NOS) in brain tissues of rats exposed to deltamethrin insecticide has been examined by histochemical NADPH-diaphorase staining techniques on frozen sections. After injection of deltamethrin (12. 5 mg/kg, i. p. ). a reproducible sequence of toxic signs of hyperexcitability were elicited. The observation and image analysis showed that, within brajn sections of rats exposed to deltamethrin, the numbers and the total staining areas of the NOS positive neurons were greatly increased, especially in cerebral cortex, hippocampal formation and paraventric-ular nucleus. In addition, the density of single neuron and the processes were also increased. The results suggested that deltamethrin may induce the NOS expression or activate the NOS activity. The NOS activation may involve in the chains responsible for the excitatory neurotoxicities induced by deltamethrin.