OBJECTIVETo determine the effect of MEK inhibitor (U0126) on donor testes from ischemia-reperfusion injury after orthotopic testicular transplantation in rats.

METHODSThe rats were divided into 7 groups, Group 1: normal control; Group 2: cold perfusion control; Group 3: sham operation control; Group 4: transplanted for 30 min; Group 5: transplanted for 1 week; Group 6: transplanted for 30 min with pretreatment of U0126; Group 7: transplanted for 1 week with pretreatment of U0126. The orthotopic testicular transplantation model was established with cuff. The levels of ERK1, ERK2, pERK1 and pERK2 of donor testes were evaluated; the change of histology and gonadal hormones were measured as well.

RESULTGroup 1, 2 and 3 had no significant differences in all results (P>0.05). The levels of ERK1, ERK2, pERK1 and pERK2 in Group 4 were significantly increased compared with Group 1 (P<0.05), the levels of ERK1 and ERK2 in Group 6 were not different from those of Group 4 (P >0.05), but the levels of pERK1 and pERK2 in Group 6 were lower than those in Group 4 significantly(P <0.05), the histological changes in Group 6 were similar to Group 1 but milder than that in Group 4. The histological injury was more severe in Group 5 than that in Group 7, and the levels of gonadal hormones in Group 5 were lower than those in Group 7 (P <0.05) which remained at the normal levels.

CONCLUSIONU0126 has a protective effect on the donor testes in a short period through inhibiting expression of pERK1/2 activated by testicular transplantation.