Akt involved in diazoxide preconditioning against rat hippocampal neuronal apoptosis induced by anoxia-reoxygenation injury

Abstract

Investigate whether preconditioning with diazoxide (DZ), a mitochondrial ATP-sensitive potassium channel opener, could enhance Akt protein to up-regulate Bcl-2/Bax protein ratio against apoptosis. Cultured for 9 - 10 d in vitro, the hippocampal neurons of Sprague-Dawley rats were assigned to the following 5 groups randomly: Control (Group A), Anoxia (Group B), Anoxia + DZ100 micromol/L (Group C), Anoxia + DZ100 micromol/L + 5-hydroxydecanoate (Group D), Anoxia + DZ100 micromol/L + LY294002 50 micromol/L (Group E). Prior to oxygen deprivation, the hippocampal neurons were treated with DZ for 1 h per day and this treatment was persisted for 3 d. Each experiment was repeated for three times and each group contained 16 wells or 2 dishes of neurons for each time. Thereafter, neurons were derived of oxygen for 4 h. At 48 h of reoxygenation the neuronal optical density (A) were measured by MTT method, while the apoptotic rates were assayed by annexin V-FITC staining. The expressions of Akt, Bcl-2 and Bax proteins were detected and evaluated by Western blot. Compared with other pretreatment, DZ 100 micromol/L led to the elevation of A, whereas promoted the decrease of apoptotic rate (P < 0.05). Compared with those in other anoxic groups, the expressions of Akt protein and Bcl-2 protein in Group C were increased significantly (P < 0.05), whereas the Bax density were reduced significantly (P < 0.05). Preceding administration of 100 micromol/L DZ took protective effects on the neurons induced by anoxia-reoxygenation. DZ 100 micromol/L increased Akt protein to up-regulate Bcl-2/Bax protein ratio against apoptosis induced by anoxia-reoxygenation.