Objective  To evaluate the effect of mild hypothermia on the renal ischemia-reperfusion injury (IRI), and the expression profile of RNA-binding motif protein 3(RBM3) and its downstream effector molecules during this process.

  Methods  Eighteen healthy SD male rats were randomly divided into the normal control (NC) group, IRI group and mild hypothermia pretreat (MHP) group, with 6 rats in each group. Serum creatinine level was measured to evaluate the renal function. Hematoxylin-eosin (HE) staining was performed to assess the renal tissue injury. Western blot was used to determine the relative expression levels of RBM3, Yes-associated protein 1(YAP1), nuclear factor E2-related factor 2(Nrf2), B cell-lymphoma-2(Bcl-2) and Bcl-2-associated X protein (Bax) in the kidney tissues. Immunohistochemical staining was employed to further detect the expression levels of RBM3 and YAP1 proteins. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay was adopted to detect the cell apoptosis of kidney tissues. Malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were evaluated to determine the oxidative stress level of kidney tissues.

  Results  Compared with the NC group, the serum creatinine level, the pathological injury score of kidney tissues and the expression levels of RBM3, YAP1 and Nrf2 proteins were significantly up-regulated, the Bcl-2/Bax ratio was considerably lower, the apoptosis rate was remarkably elevated, the MDA content was significantly increased and the SOD activity was dramatically reduced in the IRI and MHP groups (all P < 0.05). Compared with the IRI group, the serum creatinine level and the pathological injury score of kidney tissues were significantly decreased, the expression levels of RBM3, YAP1 and Nrf2 proteins were significantly up-regulated, the Bcl-2/Bax ratio was considerably higher, the apoptosis rate was significantly decreased, the MDA content was significantly decreased and the SOD activity was considerably elevated in the MHP group (all P < 0.05).

  Conclusions  Mild hypothermia may exert protective effect upon renal IRI and it could alleviate cell apoptosis and oxidative stress injury induced by IRI, probably by up-regulating the expression level of RBM3 and its downstream effector molecules of YAP1 and Nrf2.