Aeromonas hydrophila Induced Mitochondrial Dysfunction and Apoptosis in Liver and Spleen of Labeo rohita Mediated by Calcium and Reactive Oxygen Species

The study shows effect of oxidative stress on liver and spleen of L. rohita (Hamilton 1822) challenged with an asymptomatic dose (3 x 10(7) CFU/ mL) of Aeromonas hydrophila. Upon termination of the experiment, intracellular Reactive Oxygen Species (ROS), anti-oxidant enzyme activities of Super Oxide Dismutase (SOD) and Catalase (CAT), anti-oxidative enzyme concentrations of Glutathione Peroxidase (GPx), Glutathione Reductase (GR), Glutathione (GSH) were recorded where an organ specific pattern of significant changes were observed between control and treated samples. Study revealed apoptotic cell death in both organs where early and late apoptotic cells increased significantly. Mitochondrial membrane potential assay reflected higher percentage of depolarized cells in treated samples. Cytosolic free Ca2+ level was significantly higher in liver and spleen post infection and was also associated with significant increase in Caspase 3 gene expression. Evidences of severe oxidative stress in fishes resulting from an asymptomatic dose eventually causing apoptotic cell death were reported. It was observed to be mediated by effector Caspase 3 which was triggered by a complex interplay between mitochondria] dysfunction and high level of cytosolic Ca2+. Further, it indicated an intriguing observation that liver is more susceptible towards the pathogen and shows more significant changes in comparison to spleen.