Allopurinol provides long-term protection for experimentally induced testicular torsion in a rabbit model



I read with interest the article by Kehinde et al.[1]; they reported that administering allopurinol before reperfusion of the testis is associated with a prolonged reduction of free radical level and maintenance of a good Johnsen score. The authors stated that nearly all previous studies reporting beneficial effects of antioxidants were based on short-term observations and only one study to date reported long-term protective effects of antioxidants on the testis [2]. However, we also reported the long-term protective effects of 3-aminobenzamide (3-AB, an inhibitor of polyADP-ribose polymerase, PARP) on histological damage in testicular ischaemia-reperfusion injury [3].

Testicular torsion is a urological emergency.; the salvage rate is directly proportional to the duration and the degree of torsion, and early diagnosis with detorsion is the current management for preserving spermatogenesis and fertility [4]. One strategy to reduce oxidative stress involves the elimination of reactive oxygen species (ROS) by ROS scavengers. It was reported that treatment with ROS scavengers had a palliative effect on the histological changes in the testis that had had 1 h of experimental torsion, but there was no significant rescue after 1 h of testicular ischaemia [2,5]. However, we showed that 2 h of torsion with a 720° rotation of the testis, followed by 4 h of detorsion caused a significant increase in biochemical variables, including malondialdehyde levels, nitric oxide content and myeloperoxidase activity in testicular tissue, related to ischaemia-reperfusion injury and administration of PARP inhibitors before detorsion improved these biochemical variables [6].

Kehinde et al.[1] reported that, to their knowledge, only one study to date reported long-term protective effects of antioxidants on testicular torsion [2]. However, a recent study from our institution using a rat model of 2 h of testicular torsion also showed that inhibiting PARP decreases histological damage after testicular torsion followed by 60 days of recovery [3]. To our knowledge, we showed, for the first time, that 3-AB, an inhibitor of PARP, had a beneficial effect on long-term histological damage in testicular ischaemia-reperfusion injury [3]. When 3-AB was administered before detorsion, the histological factors, including mean seminiferous tubular diameter, germinal epithelial cell thickness and mean testicular biopsy score, were significantly maintained.

Unfortunately, Kehinde et al. did not mention our study [6] that reported the protective effect of PARP inhibitors on long-term (60 days) histological damage in testicular ischaemia-reperfusion injury. In addition, the data in their Table 2 are incorrect; the authors noted that the rabbits in group C had 60-min ischaemia followed by left orchidectomy (no reperfusion), but they also reported the mean values of long-term results of group C.