ObjectiveTo observe the neuron apoptosis and anti-oxidative stress function of cerebral tissues after acute cerebral ischemia/reperfusion (I/R) in rats treated with apelin in the early period of acute cerebral I/R. MethodsTotally 156 male Wistar rats were randomly divided into 3 groups: sham group (n=12), ischemia reperfusion group (I/R group, n=72) and ischemia reperfusion plus apelin group (I/R+AP group, n=72). The latter two groups were further divided into 6 subgroups according to reperfusion time (3, 6, 12, 24, 72, and 120 h groups, each group containing 12 rats). Apelin (10^-7 mol/L \[10 μl\]) was injected into the lateral ventricle in the early time of reperfusion (30 min) in the I/R+AP group. RT-PCR was used to observe the change of caspase-3 and caspase-12 mRNA expression in the injured side of cerebral cortex in each group, and flow cytometer was employed to detect the apoptosis rate of neurons. The content of malondialdehyde (MDA), activity of glutathione peroxidase (GSH-Px), and the total antioxidant capacity were also examined in the brain homogenate after I/R. ResultsThe expression of caspase-3 mRNA and caspase-12 mRNA was increased in I/R and I/R+AP groups compared with the sham group. Treatment with apelin down-regulated caspase-12 mRNA expression but had little influence on caspase-3 mRNA expression. The neuron apoptosis rate was significantly lower in I/R+AP group compared with the I/R group (P<0.05), and the changes increased with time. Compared with the sham group, I/R group had significantly increased MDA content(P<0.05) and significantly decreased GSH-Px activity and total antioxidant capacity (P<0.05). Compared with the I/R group, I/R+AP group had significantly increased GSH-Px activity and total antioxidant capacity and significantly decreased MDA content (P<0.05). ConclusionEarly intervention with apelin can protect the neurons in rats after acute cerebral I/R.