Apoptotic cell death in rat brain following deltamethrin treatment

In the present study we identified the degeneration and apoptotic cell death in rat brain after deltamethrin treatment. By hematoxylin-eosin (H&E) staining, a large number of degenerative cells (pyknosis of nuclei, disruption of eosinophilic cytoplasm) were seen in the hippocampus and cortex at 24 and 48 h after deltamethrin treatment at a dose of 12.5 mg/kg (i.p.) in corn oil. The similar morphological changes of degenerative cells were observed by cresyl violet staining. Numerous apoptotic cells were detected by in situ end labeling (ISEL) and flow cytometric analysis in the hippocampus and cortex at 24 and 48 h following deltamethrin treatment at the same dose, whereas no ISEL-positive cells were seen in the same brain regions of control rats. Moreover, using DNA gel electrophoresis, it was demonstrated that DNA fragmentation was markedly induced in the hippocampus and cortex at 24, 48 and 72 h after treatment. In addition, the protein synthesis inhibitor cycloheximide inhibited the DNA fragmentation elicited by deltamethrin in rat brain. These results indicate that deltamethrin induces degeneration and apoptotic cell death in rat brain, suggesting an important role played by apoptosis in neurotoxicity of deltamethrin.