Effect of endoplasmic reticulum stress inhibition on hyperoxaluria-induced oxidative stress: influence on cellular ROS sources.

PURPOSE: Hyperoxaluria-induced calcium oxalate crystallisation is associated with the generation of reactive oxygen species (ROS) via mitochondria and NADPH oxidase. Endoplasmic reticulum (ER) has emerged as an organelle which could influence mitochondrial functioning and ROS generation. Plugging an upstream pathway of mitochondrial and NADPH oxidase-induced ROS generation may have better prophylaxis. Therefore, we propose to investigate the linkage of hyperoxaluria-induced ROS generation with ER stress by inhibiting the later with 4-Phenylbutyric acid (4-PBA).

METHODS: Male wistar rats were divided into three groups: a normal control group, an ethylene glycol with ammonium chloride-induced hyperoxaluric group (EA) and a third group which has hyperoxaluric animals given 4-PBA at a dose of 300 mg/kg. After 9 days of treatment, animals were sacrificed and renal tissues were analysed for histopathological examination, ROS, mitochondrial dysfunction, ER stress markers, inflammatory markers and NADPH oxidase subunits expression.

RESULTS: Hyperoxaluric rats exhibited a significant increase in the levels of ROS, subsequently up-regulated levels of ER stress markers, inflammatory indicators, NADPH oxidase subunits and compromised mitochondrial functioning. However, ER stress amelioration appreciably curtailed the alterations caused by hyperoxaluric abuse.

CONCLUSIONS: Therefore, suggesting the major role of ER in hyperoxaluric manifestations thereby providing an opportunity to target ER stress for future therapeutic interventions.