Rapamycin protects testes against germ cell apoptosis and oxidative stress induced by testicular ischemia-reperfusion

Abstract

Objectives: Rapamycin is an immunosuppressant compound with a broad spectrum of pharmaco-logical activities. In recent years, it has been used successfully to decrease ischemia-reperfusion injury in several organ systems. The purpose of the present study was to examine the effect of rapamycin on testicular ischemia-reperfusion injury.

Materials and methods: Seventy-two adult male Wistar rats were divided into six groups: control (group1), sham-operated (Group2), T/D + DMSO as vehicle group (group3), and groups 4-6; respectively received 0.5, 1, and 1.5 mgkg^-1 of rapamycin, IP 30 min before detorsion. Ischemia was achieved by twisting the right testis 720° clockwise for 1 hr. The right testis of 6 animals from each group were excised 4 hr after detorsion for the measurement of lipid peroxidation, caspase-3, and antioxidant enzyme activities. Histopathological changes and germ cell apoptosis were determined by measuring mean of seminiferous tubules diameters (MSTD) and TUNEL test in right testis of 6 animals per group, 24 hr after detorsion.

Results: Testicular T/D caused increases in the apoptosis, malondialdehyde (MDA), and caspase-3 levels and decreases in the superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities in ipsilateral testis (P<0.001). The rats treated with rapamycin had significant decreases in the MDA and caspase-3 levels and significant increases in the SOD, CAT and GPx activities in ipsilateral testis compared with the T/D group (P<0.001); germ cell apoptosis was decreased, and MSTD was improved.

Conclusion: Rapamycin administration during testicular torsion decreased ischemia/reperfusion (I/R) cellular damage.

Keywords: Apoptosis; Ischemia-reperfusion; Rapamycin; Testicular torsion; Testis.

Figure 1

Histological appearances in ipsilateral testes groups: control, sham-operated, T/D, rapamycin 0.5 mg Kg-1 + T/D, rapamycin 1 mg kg-1 + T/D and rapamycin 1.5 mg kg-1 + T/D. Ischemic alterations and coagulative necrosis were observed, and the orderly arrangement of germ cells was impaired in the T/D group. After treatment with rapamycin, spermatogenesis was restarted and orderly structure of germ cells with a few mature spermatids was observed within seminiferous tubules (H&E; magnification × 100)

Figure 2

Apoptotic nuclei and seminiferous tubules using TUNEL assay. Apoptotic germ cells significantly increased following T/D. After treatment with rapamycin, especially at dose of 1.5 mg kg-¹, apoptosis indexand percentage of seminiferous tubules significantly decreased and only a few apoptotic nuclei were observed (magnification× 200)