Objective: To investigate the protective effect of dexmedetomidine (Dex) preconditioning against ischemia-reperfusion (IR) injury after testicular torsion in rats.
Methods: Fifty-six adult male rats, were randomly divided into seven groups: sham control, 1h IR, 2h IR, 4h IR, 1h IR + Dex, 2h IR + Dex, and 4h IR + Dex. The torsion model was established in the latter six groups by a counterclockwise 720° left spermatic cord torsion lasting 1, 2 and 4 hours, respectively, and the rats in the last three groups injected intraperitoneally with Dex at 100 μg/kg 30 minutes before testicular reduction. At 4 hours after testicular reduction, the testes were removed for biochemical examination of the tissue homogenate and assessment of the testicular damage based on the results of HE staining and Johnsen testicular biopsy scores.
Results: Lower levels of catalase and total superoxide dismutase were associated with longer time of ischemia (P<0.05) and higher in the IR than in the IR + Dex groups with the same duration of ischemia (P<0.05). The levels of malondialdehyde, nitric oxide and myeloperoxidase were all significantly increased in the IR and IR + Dex groups compared with those in the sham control group (P<0.05), higher with longer time of ischemia (P<0.05), but lower in the IR + Dex than in the IR group with the same length of time of ischemia (P<0.05). Histopathological examination revealed edema in the testis tissue, damage to the seminiferous tubules and germ cells and interstitial hemorrhage, more severe in the IR and IR + Dex groups than in the sham control group (P<0.05), which were all remarkably improved in the 1h IR + Dex and 2h IR + Dex groups compared with the 1h IR and 2h IR groups (P<0.05) but showed no statistically significant difference between the 4h IR and 4h IR + Dex groups (P > 0.05).
Conclusions: Dexmedetomidine protects the rat testis against testicular torsion-induced early ischemia-reperfusion injury, but it is less effective for longer ischemia than 4 hours.
Keywords: ischemia-reperfusion injury; rat; testicular torsion; dexmedetomidine.