Neuroprotective effect of phosphatase and tensin homolog allele activity deleted in chromosome 10 inhibition on neuronal apoptosis after hypoxia-ischemia

Abstract

Objective To investigate the mechanisms of neuroprotective roles of phosphatase and tensin homolog allele activity deleted in chromosome 10 (PTEN) inhibition on neuronal apoptosis after hypoxia-ischemia(HI) damage. Methods The cerebral cortical neurons of newborn Sprague-Dawley rats were cultured in vitro. Oxygen and glucose deprivation(OGD) model was established to imitate HI environment in vivo. Neurons were divided randomly into 3 groups: control group: neurons were treated with normal medium; OGD group: neurons were treated with OGD for 3 h followed by reperfusion at 0.5, 3.0, 6.0, 12.0, 24.0, 48.0 h; PTEN inhibition group: before OGD treatment, neurons were pretreated with PTEN inhibitor, and then the neurons were collected at 24 h after reperfusion. Terminal deoxynucleotidyl transferase-mediated dUTP nick and labeling staining was used to detect the apoptotic cells. Western blot was used to detect the expression of PTEN, p-PTEN, protein kinase B(Akt), p-Akt, synthesis of glucose kinase-3 betal(GSK-3β), p-GSK-3β and myeloid cell ceukemia-1(Mcl-1). Results 1. As compared with control group, TUNEL positive cells increased after OGD observed by TUNEL staining (P 0.05).2. As compared with OGD group, TUNEL positive cells were obviously reduced at 24 h after OGD in PTEN group (P 0.05), the expressions of p-PTEN, p-Akt, p-GSK-3β, and Mcl-1 were significantly increased after OGD(all P<0.05). Conclusions HI can induce neuronal apoptosis, and the mechanisms of apoptosis may involve PTEN/Akt/GSK-3β/Mcl-1 pathway. The phosphorylation of Akt and GSK-3β can be increased via PTEN activity inhibition, while the ubiquitination of Mcl-1 would be decreased, and thus reduce the neuronal apoptosis. Key words: Phosphatase and tensin homolog deleted in chromosome 10; Protein kinase B; Glycogen synthase kinase-3β; Myeloid cell leukemia-1; Apoptosis; Neuron; Hypoxia-ischemia