Free radical generation by neurons in rat model of Japanese encephalitis

Increased generation of free radicals resulting in brain injury is a feature of many viral infections. The present study has been undertaken to evaluate the level of free radicals in Japanese encephalitis. Twelve days old Wistar rats were inoculated intracerebrally with 3 x 10(6) pfu of JE virus and were sacrificed on 3, 6, 10, and 20 days post inoculation (dpi). The neuronal levels of reactive oxygen species (ROS), nitric oxide (NO), peroxinitrite (OONO(-)), necrotic and apoptotic cell population were estimated by flow cytometry. Hematoxylin-eosin staining was also performed. Maximum level of neuronal ROS and OONO(-) was observed on 6 dpi; however, NO levels peaked on 10 dpi. Free radical generation significantly declined on 20 dpi as compared to control. Apoptotic cell death gradually increased over the time. Neuronal shrinkage and necrosis was also observed. The results of our study indicate that free radicals increased in acute JE and declined at later stage, which may contribute to cell death.