[Protective effects of inhibition of tissue nitric oxide in the initial stage against tardive injury of testicular spermatogenic function: experiment with rats].

Objective: To study the protective effects of inhibition of tissue nitric oxide in the initial stage against the tardive injury of contralateral testicular spermatogenic function after unilateral testicular torsion.

Methods: 56 prepubertal Sprague-Dawley rats were randomly divided into 4 equal groups: placebo group undergoing rotation of left testis 720 degrees clockwise for 4 h, fixing thereof to the scrotum, and then intravenous injection of normal saline; cyclosporine group, undergoing intraperitoneal injection of cyclosporine once daily for 1 month after the testicular rotation and fixation; NG-methyl L-arginine (L-NMMA) group, undergoing intravenous injection of L-NMMA 30 mg/kg 30 min before the testicular rotation; and sham-operation group, undergoing isolation and suture of testis only. The right (untwisted) testes were removed from 7 rats from each group 1 week and 2 months after surgery. The malondialdehyde (MDA) level and nitrous oxide (NO)/nitrogen oxide synthase (NOS) content were evaluated. Histological examination was conducted. The mean seminiferous tubule diameter (MSTD) was assessed. The level of MHC peptide-tetramer complex was determined by flow cytometry.

Results: The levels of MDA, NO, NOS, and MHC peptide-tetramer complex of the L-NMMA, placebo, and cyclosporine groups one week after surgery were all significantly higher than those of the sham operation group (all P < 0.05). The levels of MDA, NO, NOS, and MHC peptide-tetramer complex of the L-NMMA group were all significantly lower then those of the placebo group (all P < 0.05). The pathological damage of the contralateral testis in early and late stages in the L-NMMA group was lighter than in the placebo group.

Conclusion: By inhibiting tissue NO production in focal organizations during the early period, L-NMMA reduces the damages inthe testis contralateral to the testis undergoing unilateral torsion.