Indomethacin, a Non-steroidal Anti-inflammatory Drug,\ud Develops Gastropathy by Inducing Reactive Oxygen\ud Species-mediated Mitochondrial Pathology and Associated\ud Apoptosis in Gastric Mucosa:\ud A NOVEL ROLE OF MITOCHONDRIAL ACONITASE OXIDATION

摘要

We have investigated the role of mitochondria on the development\udof indomethacin (a non-steroidal anti-inflammatory\uddrug)-induced gastric mucosal apoptosis and associated gastropathy\udin rat. Transmission electron microscopic studies indicate\udthat indomethacin damages mitochondrial ultrastructure\udand causes mitochondrial dysfunction as evident from\uddecreased stage-3 respiration, dehydrogenase activity, and\udtransmembrane potential (��m). Mitochondrial pathology is\udassociated with increased generation of intra-mitochondrial-reactive\udoxygen species, such as O2 . , H2O2 and �OH, leading to\udoxidative stress. O2 . is the most effective to damage mitochondrial\udaconitase, leading to the release of iron from its iron-sulfur\udcluster. The released iron, by interacting with intra-mitochondrial\udH2O2, forms �OH. Immunoprecipitation of mitochondrial\udaconitase and subsequent Western immunoblotting indicate\udcarbonylation of aconitase along with the loss of activity in vivo\udafter indomethacin treatment. The release of iron has been documented\udby fluorescence imaging of mucosal cells by using Phen\udGreen SK, a specific probe for chelatable iron. Interestingly,\udintra-mitochondrial �OH generation is crucial for the development\udof mitochondrial pathology and activation of mitochondrial\uddeath pathway by indomethacin. Scavenging of �OH by dimethyl\udsulfoxide or �-phenyl-n-tert-butylnitrone, a spin-trap,\udprevents indomethacin-induced mitochondrial ultrastructural\udchanges, oxidative stress, collapse of ��m, and mitochondrial\uddysfunction. The scavengers also restore indomethacin-induced\udactivation of caspase-9 and caspase-3 to block mitochondrial\udpathway of apoptosis and gastric mucosal damage. This\udstudy, thus, reveals the critical role of O2 . -mediated mitochondrial\udaconitase inactivation to release intra-mitochondrial iron,\udwhich by generating �OHpromotes gastric mucosal cell apoptosis\udand gastropathy during indomethacin treatment.