Antioxidant potential of Minocycline in Japanese Encephalitis Virus infection in murine neuroblastoma cells: Correlation with membrane fluidity and cell death

Minocycline is neuroprotective in animal models of a number of acute CNS injuries, neurodegenerative diseases and CNS infection. While anti-inflammatory and anti-apoptotic effects of Minocycline have been characterized, the molecular basis for the neuroprotective effects of Minocycline remains unclear. We report here that Minocycline and two classical antioxidant compounds inhibit the Japanese Encephalitis Virus (JEV)-induced free radical generation in mouse neuroblastoma. In cultures of Neuro2a (N2a) cells infected with JEV for up to 24 h, the number of cells undergoing cell death was also reduced by Minocycline (20 μM). JEV infection resulted in increased oxidative stress, as revealed by an increase in the fluorescence intensity for 5-(and-6)-chloromethyl-2′,7′-dichlorodihydrofluorescein diacetate (CM-H2DCFDA), a reactive oxygen species (ROS) indicator. Minocycline at 20 μM inhibited this ROS production. Cells were moderately protected from JEV-induced death by diphenyleneiodonium (DPI), an inhibitor of flavon-containing enzyme inhibitor, whereas common antioxidants such as N-acetyl-cysteine (NAC) turned out to be ineffective. Direct antioxidant property of Minocycline and reference antioxidant compounds is evaluated by LDH assay, ROS measurement and mitochondrial membrane potential measurement. Our findings suggest that Minocycline reduces the neuronal damage seen in JEV infection in neuronal cell culture models at least in part through inhibition of oxidative stress.