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

To assess the effect of five antioxidants on exocrine function of rabbit testes retained in situ for 24 h and 3 months after experimental torsion.

The left testes of peripubertal rabbits were clamped for 60 min, after which the clamps were removed and the testes allowed to reperfuse. The right testes served as internal controls. There were eight rabbits in each of the following experimental groups: (a) sham; (b) 60-min ischaemia followed by reperfusion; (c) 60-min ischaemia followed by left orchidectomy. In five further groups, rabbits were exposed to 60-min ischaemia followed by reperfusion, but received one of the following antioxidants before reperfusion: acetyl salicylic acid, ascorbic acid, allopurinol, quercetin or superoxide dismutase. Both testes were excised at 24 h or 3 months. The degree of lipid peroxidation, a measure of free radical damage, was assessed in testicular tissue homogenates by measuring the tissue levels of malondialdehyde (MDA). The Johnsen score was used to assess the morphological damage at 24 h and 3 months for each group.

At 3 months twisted viable testes allowed to reperfuse had higher MDA levels than controls; the left testes of rabbits treated with allopurinol had significantly lower MDA levels than untreated rabbits and rabbits given other antioxidants. Rabbits given quercetin, ascorbic acid or superoxide dismutase had lower (but not significantly) left testicular MDA levels than untreated rabbits, while rabbits given acetyl salicylic acid had even higher levels. Allopurinol-treated rabbits had a Johnsen score of > 7.6 and those given other antioxidants had scores of < 7.6 at 3 months.

The twisted viable testis treated by orchidopexy contains high free radical levels at 3 months. Of the antioxidants studied, only allopurinol had a beneficial long-term effect, by significantly reducing testicular MDA levels at 3 months.