OBJECTIVETo investigate the protective effect of ischemic postconditioning (IP) against different degrees of testicular ischemia-reperfusion (IR) injury in rabbits.

METHODSForty-two white male rabbits were equally randomized into 7 groups: a control, 3 IR (R1, R2 and R3), and 3 IP (P1, P2 and P3) groups. Testicular models of different degrees of ischemia were established in the IR and IP groups. Before reperfusion, ultrasonography showed homogeneous echoes with slightly decreased blood flow in R1 and P1, heterogeneous echoes with obviously decreased blood flow in R2 and P2, lamellar or fragmental low echo areas absent of blood flow signals in R3 and P3. Then the IR groups were directly subjected to perfusion, and the IP groups to 3 episodes of 30-second reperfusion followed by 30-second ischemia. All the groups underwent contrast-enhanced ultrasonography (CEUS) before reperfusion and, after 3 days, examined for the contents of malonaldehyde (MDA), superoxide dismutase (SOD) and histology, and observed for the pathological changes of the testicular tissue.

RESULTSBefore reperfusion, no significant differences were found in the CEUS parameters beta, time-to- peak (TTP), peak-base intensity (PBD) and half of declining time (DT/2) between R1 and P1, R2 and P2, and R3 and P3 (P>0.05). There were remarkable differences in MDA and SOD between R1 and P1, and R2 and P2 (P<0.05), but not between R3 and P3 (P >0.05). Johnson's score, apoptosis index and ultrastructure showed marked differences between R1 and P1 (P<0.05) but not between R2 and P2, and R3 and P3 (P >0.05).

CONCLUSIONIP can attenuate IR-induced testis injury, but the effect varies with the degree of ischemia, and its pathological manifestation differs from the biochemical one.