Dynamic changes of mitochondrial fission proteins after transient cerebral ischemia in mice

With fusion or fission, mitochondria alter their morphology in response to various physiological and pathological stimuli resulting in either elongated, tubular, interconnected or fragmented form. Immunohistochemistry and Western blot analyses were performed at 2, 7, 14 and 28 d after 90 min of transient middle cerebral artery occlusion (tMCAO) in mice. The present study showed that mitochondrial fission protein fission 1 (Fis1) and phosphorylated dynamin-related protein 1 (P-Drp1) both progressively increased with the peak at 14 d after tMCAO. Double immunofluorescent analysis showed the number of double positive cells with Fis1/Drp1 reduced between 2 and 28 d after 90 min of tMCAO, and also showed some double positive cells with Fis1/terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL) in the peri-infract regions at 2 d after the reperfusion. The present study suggests a progressive activation of mitochondrial fission proteins Fis1 and P-Drp1 in relation to apoptotic process in neural cells of the peri-infract regions after tMCAO.