RESUMO
<p><b>OBJECTIVE</b>To explore the effects of glial cell-derived neurotrophic factor (GDNF) on the stem cell factor (SCF), superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) in the undescended testis tissue of rats.</p><p><b>METHODS</b>Models of left cryptorchidism were made in 48 healthy male rats weighing (200 +/- 20) g and randomly divided into four groups: model control, GDNF 7 d, GDNF 14 d and GDNF 21 d. The rats in the latter three groups were killed at 7, 14 and 21 days after intravenous injection of GDNF, their left testes harvested for measurement of the activities of SOD and CAT and the content of MDA. The apoptosis index of spermatogenic cells was detected by TUNEL, the histological changes of the testis tissue observed under the light microscope, and the gene and protein expressions of SCF determined by real-time quantitative PCR and Western blotting, respectively.</p><p><b>RESULTS</b>The apoptosis indexes of spermatogenic cells were obviously decreased in the GDNF 7 d, GDNF 14 d and GDNF 21 d groups (8.42 +/- 0.16, 4.45 +/- 0.34 and 7.32 +/- 0.09) as compared with that of the model control (13.5 +/- 0.64), with statistically significant difference between the GDNF 14 d and control groups (P < 0.01). The SCF expression and SOD activity were remarkably increased while the MDA content markedly reduced in the GDNF groups in comparison with those in the model control (P < 0.01).</p><p><b>CONCLUSION</b>GDNF had a protective effect on the spermatogenic function of rat testes with unilateral cryptorchidism. It could enhance the antioxidant enzyme activity of the antioxidant enzyme system, elevate the expression of SCF and thus improve the testicular reproductivity, which were best indicated in the GDNF 14 d group.</p>