Allopurinol protects enterocytes from hypoxia-induced apoptosis in vivo

Reactive oxygen species can cause apoptosis and may be involved in hypoxic injury to the small bowel. Xanthine oxidase (XO) has been implicated in reactive oxygen species production. We hypothesized that administration of allopurinol would protect rat enterocytes from hypoxia-induced apoptosis.

Twenty-four Sprague-Dawley rats (weight, 250-300 g) were subjected to 30 minutes of hypoxia (10% Fio(2)), then killed immediately or allowed to recover for an hour in room air (21% Fio(2)). Intraperitoneal allopurinol (50 mg/kg) or an equivalent amount of 0.9% saline was administered 1 hour before hypoxia. Control rats were exposed to 21% Fio(2) under similar conditions. Proximal jejunum was harvested from all animals in both groups and stained to detect apoptotic cells using terminal deoxynucleotidyl transferase-mediated biotinylated deoxynucleotide end labeling. In addition, sections of proximal jejunum were removed and the mucosal membrane was removed and flash frozen in liquid nitrogen for DNA fragmentation gel.

Intraperitoneal administration of allopurinol significantly reduced the percentage of apoptotic villi in the proximal jejunum compared with those animals receiving saline (11 +/- 7 vs. 25 +/- 12 in the hypoxia no recovery group, 41 +/- 14 vs. 67 +/- 8 in the hypoxia with recovery group, mean +/- SD, Mann-Whitney test, < 0.05). Intestinal XO activity was also significantly reduced in the animals receiving allopurinol compared with those receiving saline (6.8 +/- 3.12 vs. 19.1 +/- 4.56 mU/mL/g wet tissue in the hypoxia no recovery group, 0.86 +/- 0.33 vs. 11.5 +/- 7.13 mU/mL/g wet tissue in the hypoxia with recovery group, mean +/- SD, Mann-Whitney test, < 0.05).

Inhibition of XO appears to protect rat enterocytes from hypoxia-induced apoptosis in vivo.