Role of Nrf2 signal pathway in rats with deep hypothermia ischemia/reperfusion injury undergoing remote postconditioning.

We investigated the protective effects of remote postconditioning (RPC) in the lungs of rats with deep hypothermia ischemia/reperfusion (I/R) injury and the role of nuclear factor E2-related factor 2 (Nrf2) signaling in this process. Forty-nine rats were randomly divided into a sham control group, deep hypothermia I/R group, RPC group, I/R+all-trans retinoic acid (ATRA) group, I/R+RPC+ATRA group, I/R+tert-butylhydroquinone (tBHQ) group, and I/R+RPC+tBHQ group. Real-time polymerase chain reaction and Western blot analysis were used to examine Nrf2 mRNA and protein expression, respectively. Compared with the sham control group, Nrf2 expression, malondialdehyde (MDA) content, and the wet/dry weight (W/D) ratio were significantly increased in the I/R group, while superoxide dismutase (SOD) activity was significantly decreased. Pulmonary Nrf2 expression and SOD activity was significantly increased, and MDA content and the W/D ratio were significantly decreased in the RPC group compared with the I/R group. Compared with the I/R group, MDA and W/D ratio significantly decreased and SOD activity remarkably increased in I/R+tBHQ group. After ATRA intervention in the I/R+ATRA group, MDA content and W/D ratio increased and SOD activity decreased compared to the I/R group. MDA content and W/D ratio in the RPC+tBHQ group significantly decreased and SOD activity increased compared with in the RPC group (P < 0.01). In the RPC+ATRA group, MDA content and W/D ratio decreased while SOD activity increased compared with the RPC group (P < 0.01). RPC alleviated deep hypothermia I/R injury; the Nrf2 signaling pathway may be involved in the protective effects induced by RPC.