RESUMO
Purpose To observe the autophagy activation of renal tubular epithelial cells during rat renal ischemia-reperfusion ( I/R) injury, and then explore the possible mechanisms of the protective role of autophagy. Methods Forty male Wistar rats were randomly divided into the following four groups: (1) sham operation group (Sham), (2) I/R, (3) chloroquine intervention group (I/R+CQ), (4) rapamycin intervention group (I/R +Rap). The specimens of blood and kidney were collected after reperfusion of 24 hours. The serum creatinine ( Scre) and blood urea nitrogen ( BUN) levels were measured from blood samples. Tissue samples of the kidney were stained with HE to observe the pathological changes. Apoptotic cells in the kidney sections were detected using the termi-nal deoxynucleotidyl transferase dUTP nick end labeling ( TUNEL) assay. Immunohistochemistry was used to detect the expression of Beclin-1 and Caspase-3. The structures of autophagic vacuoles were revealed by transmission electron microscopy. Results Compared to I/R group, the I/R+CQ group presented higher levels of BUN and Scre (P<0. 05, P<0. 01), higher renal tissue injury scores (P<0. 01), increased TUNEL-positive cells (P<0. 05), down-regulation of Beclin-1 (P<0. 01) and up-regulation of Caspase-3 (P<0. 01), as well as reduced number of autophagic vacuoles (P<0. 05). On the contrary, I/R+Rap group exhibited lower levels of BUN and Scre (P<0. 01), decreased renal tissue injury scores (P<0. 05), increased TUNEL-positive cells (P<0. 05), up-regula-tion of Beclin-1 (P<0. 01) and down-regulation of Caspase-3 (P<0. 01), as well as increased autophagic vacuoles (P<0. 05). Conclusion Activated autophagy provided a protective role in the kidney I/R injury through inhibiting apoptosis, and the mechanisms may be involved in the regulation of Beclin-1 and Caspase-3.