Uric acid and allantoin in an experimental model of stress.

GIRAUD BILLOUD, MAXIMILIANO; VEGA, ISRAEL A; CASTRO-VAZQUEZ, ALFREDO

San Luis

Congreso; XXIV Reunión Científica Anual de la Sociedad de Biología de Cuyo.; 2006

Sociedad de Biología de Cuyo

The South American applesnail Pomacea canaliculata accumulates uric acid in large and ubiquitous stores throughout its body. This snail may undergo a period of seasonal dormancy (called “estivation”) when the limnotopes they inhabit dry up, and uric acid may serve an antioxidant role when dormancy is interrupted and a reperfusion oxidative stress follows. In the current study we found that uric acid content of the snail significantly increased during estivation, and that it dropped significantly within 24 hours after raising from dormancy; uric acid is not excreted in this species, and therefore, the decrease in uric acid stores should be explained by alternative mechanisms. We have also found that allantoin  (an oxidation product of uric acid) is accumulated during estivation, and its accumulation disminishes 24 hours after reactivation. Notably, allantoin excretion increased after reactivation, while the excretion of urea and ammonia decreased, suggesting that uric acid was indeed acting as an antioxidant compound during reactivation. However, the reactivation-induced decrease of the snail’s total uric acid content cannot be quantitatively explained by its transformation into allantoin since the excreted amounts are very low if compared to the tissue amounts. Hence, other fates for uric acid should be looked for in future studies. However, regarding the possible role of uric acid as an antioxidant compound, it should be emphasized that its antioxidant activity should be restricted to the comparatively small circulating fraction of this purine, and that its transformation into allantoin should probably occur only there.