Non-invasive remote limb ischemic postconditioning protects rats against focal cerebral ischemia by upregulating STAT3 and reducing apoptosis

The signal transducer and activator of transcription 3 (STAT3) signaling pathway has been implicated in cell apoptosis and inflammatory processes. Ischemic preconditioning (IPC) and ischemic postconditioning (IPTC) inhibit both of these processes. In the present study, we investigated the role of phosphorylated STAT3 (p-STAT3)-mediated apoptosis and inflammation following non-invasive remote limb IPTC (NRIPoC) using a classic rat model of focal cerebral ischemia. Forty-five adult male Sprague-Dawley rats were divided randomly into 3 groups (n=15 per group): the sham-operated, ischemia/reperfusion (I/R) and NRIPoC groups. NRIPoC was implemented at the beginning of reperfusion. At 24 h after cerebral reperfusion, we evaluated the neurological deficit score (NDS), assessed the cerebral infarct size and tissue morphology, and evaluated neuronal apoptosis. The protein expression levels of Bcl-2, Bax, nuclear factor-κB (NF-κB), tumor necrosis factor-α (TNF-α) and p-STAT3 in the penumbra region were assessed by western blot analysis. The cerebral infarct volume, the number of apoptotic cells and the protein expression levels of Bcl-2, Bax, NF-κB and TNF-α were all found to be increased in the I/R group compared with the sham-operated group. However, these levels were decreased in the NRIPoC group compared with the I/R group. The number of apoptotic cells in the penumbra in the I/R group was increased compared with that in the NRIPoC and sham-operated groups. The protein expression of p-STAT3 was increased in the NRIPoC group compared with the sham-operated and I/R groups. These results indicate that the protective effects of NRIPoC against cerebral I/R injury may be related to the attenuation of neuronal apoptosis and inflammation through the activation of STAT3.